U.S. patent application number 10/919295 was filed with the patent office on 2005-04-14 for process for producing an electrode material for a rechargeable lithium battery, an electrode structural body for a rechargeable lithium battery, process for producing said electrode structural body, a rechargeable lithium battery in which said electrode structural body is used, and a process for pro.
This patent application is currently assigned to Canon Kabushiki Kaisha. Invention is credited to Kawakami, Soichiro, Umeyama, Hiroya, Yamamoto, Tomoya.
Application Number | 20050079414 10/919295 |
Document ID | / |
Family ID | 18588052 |
Filed Date | 2005-04-14 |
United States Patent
Application |
20050079414 |
Kind Code |
A1 |
Yamamoto, Tomoya ; et
al. |
April 14, 2005 |
Process for producing an electrode material for a rechargeable
lithium battery, an electrode structural body for a rechargeable
lithium battery, process for producing said electrode structural
body, a rechargeable lithium battery in which said electrode
structural body is used, and a process for producing said
rechargeable lithium battery
Abstract
A process for producing an electrode material for a rechargeable
lithium battery, comprising the steps of mixing a metal compound
(a) of a metal (a') capable of being electrochemically alloyed with
lithium, a transition metal compound (b) of a transition metal (b')
and a complexing agent (c) with a solvent (d) to obtain a mixed
solution, mixing a reducing agent (e) with said mixed solution to
obtain a mixture, and oxidizing said reducing agent in said mixture
to reduce ion of said metal (a') and ion of said transition metal
(b') to obtain an amorphous alloy material capable of being
electrochemically alloyed with lithium as said electrode material.
An electrode structural body in which said electrode material is
used, and a rechargeable lithium battery in which said electrode
material is used.
Inventors: |
Yamamoto, Tomoya; (Nara-shi,
JP) ; Kawakami, Soichiro; (Nara-shi, JP) ;
Umeyama, Hiroya; (Toyota-shi, JP) |
Correspondence
Address: |
FITZPATRICK CELLA HARPER & SCINTO
30 ROCKEFELLER PLAZA
NEW YORK
NY
10112
US
|
Assignee: |
Canon Kabushiki Kaisha
Tokyo
JP
|
Family ID: |
18588052 |
Appl. No.: |
10/919295 |
Filed: |
August 17, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10919295 |
Aug 17, 2004 |
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09804191 |
Mar 13, 2001 |
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6835332 |
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Current U.S.
Class: |
429/218.1 ;
429/226; 429/231.5 |
Current CPC
Class: |
H01M 4/525 20130101;
H01M 4/387 20130101; H01M 4/131 20130101; H01M 4/0461 20130101;
H01M 4/13 20130101; Y02E 60/10 20130101; H01M 4/134 20130101; C22B
26/12 20130101; H01M 4/0442 20130101; H01M 10/44 20130101; H01M
4/40 20130101; Y10T 29/49108 20150115; H01M 4/38 20130101; H01M
10/0525 20130101; H01M 4/1391 20130101; H01M 4/1395 20130101; H01M
2004/027 20130101 |
Class at
Publication: |
429/218.1 ;
429/226; 429/231.5 |
International
Class: |
H01M 004/58; H01M
004/36 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 13, 2000 |
JP |
2000-069100 |
Claims
1-80. (canceled)
81. A rechargeable lithium battery comprising at least an anode, a
cathode, and an electrolyte and in which oxidation-reduction
reaction of lithium is used, characterized in that said anode
comprises an electrode structural body comprising: a collector
comprising a material incapable of being alloyed with lithium in an
electrochemical reaction; and an electrode material for a
rechargeable lithium battery, produced by a process in which an
oxidation-reduction reaction is used, said process comprising the
steps of: (1) mixing at least one kind of a metal compound (a)
selected from the group consisting of metal salts of a metal (a')
and metal complexes of a metal (a'), at least one kind of a
transition metal compound (b) selected from the group consisting of
transition metal salts of a transition metal (b') and transition
metal complexes of a transition metal (b'), and a complexing agent
(c) with a solvent (d) to obtain a mixed solution, said metal (a')
being capable of being electrochemically alloyed with lithium, (2)
mixing a reducing agent (e) with said mixed solution to obtain a
mixture with a pH of less than 2, and (3) oxidizing said reducing
agent (e) contained in said mixture obtained in said step (2) to
reduce an ion of said metal (a') and an ion of said transition
metal (b'), both of which are contained in said mixture obtained in
step (2), by adding an alkali to said mixture obtained in said step
(2) so that the pH value of said mixture obtained in step (2) is
changed from less than 2 to a value in a range of from 3 to 12,
whereby an amorphous alloy material capable of being
electrochemically alloyed with lithium as said electrode material
is obtained.
82. A rechargeable lithium battery according to claim 81, wherein a
layer comprising said electrode material is formed on said
collector.
83. A rechargeable lithium battery according to claim 81, wherein a
layer comprising said electrode material and a binder is formed on
said collector.
84. A rechargeable lithium battery according to claim 83, wherein
said binder comprises a water-soluble organic polymer material.
85. A rechargeable lithium battery according to claim 81, wherein a
layer comprising said electrode material, an electrically
conductive auxiliary, and a binder is formed on said collector.
86. A rechargeable lithium battery according to claim 85, wherein
said binder comprises a water-soluble organic polymer material.
87. A rechargeable lithium battery according to claim 81, wherein
said cathode comprises a lithium-containing electrode material.
88. A rechargeable lithium battery according to claim 81, wherein
said amorphous alloy material is a powdery amorphous alloy material
containing an amorphous metallic material.
89. A rechargeable lithium battery according to claim 88, wherein
said powdery amorphous alloy material has a main peak having a half
width of more than 0.2.degree. in X-ray diffraction using
K.alpha.-rays of Cu as a radiation source.
90. A rechargeable lithium battery according to claim 88, wherein
said powdery amorphous alloy material has a main peak having a half
width of more than 0.5.degree. in X-ray diffraction using
K.alpha.-rays of Cu as a radiation source.
91. A rechargeable lithium battery according to claim 88, wherein
said powdery amorphous alloy material has a peak appeared in a
range of 2.theta.=25.degree. to 50.degree. in X-ray diffraction
using K.alpha.-rays of Cu as a radiation source, having a half
width of more than 0.2.degree..
92. A rechargeable lithium battery according to claim 88, wherein
said powdery amorphous alloy material has a peak appeared in a
range of 2.theta.25.degree. to 50.degree. in X-ray diffraction
using K.alpha.-rays of Cu as a radiation source having a half width
of more than 0.5.degree..
93. A rechargeable lithium battery according to claim 88, wherein
said powdery amorphous alloy material has a crystallite size
calculated from X-ray diffraction analysis, which is less than 50
nm.
94. A rechargeable lithium battery according to claim 88, wherein
said powdery amorphous alloy material has a crystallite size
calculated from X-ray diffraction analysis, which is less than 20
nm.
95. A rechargeable lithium battery according to claim 81, wherein
said metal (a') comprises at least one kind of a metal selected
from the group consisting of Bi, In, Pb, Si, Ag, Sr, Ge, Zn, Sn,
Cd, Sb, Tl, and Hg.
96. A rechargeable lithium battery according to claim 81, wherein
said metal (a') comprises at least one kind of a metal selected
from the group consisting of Bi, In, Pb, Zn, Sn, Sb and Tl.
97. A rechargeable lithium battery according to claim 81, wherein
said metal (a') substantially comprises Sn.
98. A rechargeable lithium battery according to claim 97, wherein
said amorphous alloy material contains an amorphous Sn.A.X alloy
with a substantially non-stoichiometric ratio composition, with A
being at least one kind of a transition metal element, and X being
at least one kind of an element selected from the group consisting
of B, C, N, O, P, and S, where the element X is not always
necessary to be contained, and said amorphous Sn.A.X alloy has a
relationship of Sn/(Sn+A+X)=20 to 80 atomic percent in terms of the
atom number of each element.
99. A rechargeable lithium battery according to claim 81, wherein
said transition metal (b') comprises at least one kind of a
transition metal selected from the group consisting of Cr, Mn, Fe,
Co, Ni, Cu, Mo, Tc, Ru, Rh, Pd, Ag, Os, Ir, Pt, Au, Ti, V, Y, Sc,
Zr, Nb, Hf, Ta, and W.
100. A rechargeable lithium battery according to claim 81, wherein
said transition metal (b') comprises at least one kind of a
transition metal selected from the group consisting of Cr, Mn, Fe,
Co, Ni, Cu, Ru, Rh, Pd, Ag, Os, Ir, Pt, and Au.
101. A rechargeable lithium battery according to claim 81, wherein
said transition metal (b') comprises at least one kind of a
transition metal selected from the group consisting of Cr, Mn, Fe,
Co, Ni, and Cu.
102. A rechargeable lithium battery according to claim 98, wherein
said amorphous alloy material has a peak appeared in a range of
2.theta.=25.degree. to 50.degree. in X-ray diffraction using
K.alpha.-rays of Cu as a radiation source, having a half width of
more than 0.2.degree..
103. A rechargeable lithium battery according to claim 98, wherein
said amorphous alloy material has a peak appeared in a range of
2.theta.=25.degree. to 50.degree. in X-ray diffraction using
K.alpha.-rays of Cu as a radiation source, having a half width of
more than 0.5.degree..
104. A rechargeable lithium battery according to claim 98, wherein
said amorphous alloy material has a crystallite size calculated
from X-ray diffraction analysis, which is less than 50 nm.
105. A rechargeable lithium battery according to claim 98, wherein
said amorphous alloy material has a crystallite size calculated
from X-ray diffraction analysis, which is less than 20 nm.
106. A rechargeable lithium battery according to claim 81, wherein
said amorphous alloy material has an average particle size in a
range of from 0.1 to 2 .mu.m.
107. A rechargeable lithium battery according to claim 81, wherein
said amorphous alloy material has an average particle size in a
range of from 0.1 to 1 .mu.m.
108. A rechargeable lithium battery according to claim 106, wherein
said amorphous alloy material has a particle size distribution in a
range of from 0.01 to 20 .mu.m.
109. A rechargeable lithium battery according to claim 106, wherein
said amorphous alloy material has a particle size distribution in a
range of from 0.05 to 1 .mu.m.
110. A rechargeable lithium battery according to claim 106, wherein
said amorphous alloy material has an average value of (longest
length of particle)/(shortest length of particle), which is in a
range of from 1.0 to 2.0.
111. A rechargeable lithium battery according to claim 106, wherein
said amorphous alloy material has an average value of (longest
length of particle)/(shortest length of particle), which is in a
range of from 1.0 to 1.5.
112. A rechargeable lithium battery according to claim 81, wherein
said amorphous alloy material has a specific surface area of more
than 10 m.sup.2/g.
113. A rechargeable lithium battery according to claim 81, wherein
said amorphous alloy material has a specific surface area of more
than 30 m.sup.2/g.
114. A rechargeable lithium battery according to claim 81, wherein
said metal compound (a) is soluble in said solvent (d).
115. A rechargeable lithium battery according to claim 81, wherein
said metal compound (a) comprises at least one kind of a metal salt
selected from a group consisting of chlorides, sulfates and
nitrates of said metal (a').
116. A rechargeable lithium battery according to claim 81, wherein
said metal compound (a) comprises at least one kind of a metal salt
selected from a group consisting of chlorides, sulfates and
nitrates of Sn.
117. A rechargeable lithium battery according to claim 81, wherein
said transition metal compound (b) is soluble in said solvent
(d).
118. A rechargeable lithium battery according to claim 81, wherein
said transition metal compound (b) comprises at least one kind of a
metal salt selected from the group consisting of chlorides,
sulfates and nitrates of said transition metal (b').
119. A rechargeable lithium battery according to claim 81, wherein
said complexing agent (c) comprises at least one kind of a compound
selected from a group consisting of organic carboxylic acids and
amines.
120. A rechargeable lithium battery according to claim 119, wherein
said complexing agent (c) comprises at least one kind of a compound
selected from the group consisting of citric acids,
ethylenedianminetetraacetic acid, and salts thereof.
121. A rechargeable lithium battery according to claim 81, wherein
said reducing agent (e) comprises a material having an electrode
potential which is inferior by more than 0.1 V to that of said
metal (a') or said transition metal (b') which is the lowest.
122. A rechargeable lithium battery according to claim 81, wherein
said reducing agent (e) comprises a material having an electrode
potential which is inferior by more than 0.2 V to that of said
metal (a') or said transition metal (b') which is the lowest.
123. A rechargeable lithium battery according to claim 81, wherein
said reducing agent (e) comprises a material having a property that
an aqueous solution of said material maintained at 25.degree. C.
exhibits a normal electrode potential al of less than -0.2 V.
124. A rechargeable lithium battery according to claim 81, wherein
said reducing agent (e) comprises a material having a property that
an aqueous solution of said material maintained at 25.degree. C.
exhibits a normal electrode potential of less than -0.5 V.
125. A rechargeable lithium battery according to claim 81, wherein
said reducing agent (e) comprises at least one kind of a compound
selected from the group consisting of lower oxygen compounds
selected from the group consisting of hypophosphorous acid,
phosphorous acid, sulfurous acid, thiosulfuric acid, and dithionous
acid; salts of these compounds; metal salts in the low valence
state of Fe (II), Ti (III) and Cr (II); organic compounds selected
from the group consisting of formaldehyde, formic acid, and oxalic
acid; and salts of these organic compounds.
126. A rechargeable lithium battery according to claim 81, wherein
said reducing agent (e) is soluble in said solvent (d).
127. A rechargeable lithium battery according to claim 81, wherein
said solvent (d) comprises at least one kind of a solvent selected
from the group consisting of water and polar solvents.
128. A rechargeable lithium battery according to claim 81, wherein
said polar solvent includes alcohol, ester compounds, amide
compounds, nitrile compounds, amine compounds, halogen compounds,
sulfur compounds, liquid ammonia, and glacial acetic acid.
129. A rechargeable lithium battery according to claim 81, wherein
said solvent comprises at least one kind of a solvent selected from
a group consisting of water and alcohols.
130. A rechargeable lithium battery according to claim 81, wherein
said mixed solution obtained in said step (1) contains a complex
formed by said metal (a') and said complexing agent (c).
131. A rechargeable lithium battery according to claim 81, wherein
said mixed solution obtained in said step (1) contains a complex
formed by said transition metal (b') and said complexing agent
(c).
132. A rechargeable lithium battery according to claim 81, wherein
the step (2) of mixing the reducing agent (e) with the mixed
solution obtained in the step (1) is performed under condition with
a temperature of -10 to 100.degree. C.
133. A rechargeable lithium battery according to claim 81, wherein
the step (2) of mixing the reducing agent (e) with the mixed
solution obtained in the step (1) is performed under condition with
a temperature of 10 to 90.degree. C.
134. A rechargeable lithium battery according to claim 81, wherein
the step (3) of oxidizing the reducing agent (e) contained in the
mixture obtained in the step (2) is performed under condition with
a temperature of -10 to 100.degree. C.
135. A rechargeable lithium battery according to claim 81, wherein
the step (3) of oxidizing the reducing agent (e) contained in the
mixture obtained in the step (2) is performed under condition with
a temperature of 10 to 90.degree. C.
136. A rechargeable lithium battery according to claim 81, wherein
the addition of said alkali in the step (3) is performed so that
the pH value of the mixture is changed from less than 2 to a value
in at range of from 5 to 10.
137. A rechargeable lithium battery according to claim 81, wherein
the alkali comprises at least one kind of a compound selected from
the group consisting of hydroxides of alkali metals, hydroxides of
alkaline earth metals, amines, and ammonia.
138. A rechargeable lithium battery according to claim 81, wherein
the step (2) is performed in an atmosphere comprising at least one
kind of a gas selected from the group consisting of hydrogen gas,
nitrogen gas, and inert gas selected from the group consisting of
argon gas and helium gas.
139. A rechargeable lithium battery according to claim 81, wherein
the step (3) is performed in an atmosphere comprising at least one
kind of a gas selected from the group consisting of hydrogen gas,
nitrogen gas, and inert gas selected from the group consisting of
argon gas and helium gas.
140. A rechargeable lithium battery according to claim 81, wherein
the metal compound (a) and the transition metal compound (b) are
used respectively in such an amount that (the number of moles of
the metal (a') in the metal compound (a))/(the number of moles of
the transition metal (b') in the transition metal compound (b))
falls in a range of from 0.1 to 10.
141. A rechargeable lithium battery according to claim 81, wherein
the metal compound (a) and the transition metal compound (b) are
used respectively in such an amount that (the number of moles of
the metal (a') in the metal compound (a))/(the number of moles of
the transition metal (b') in the transition metal compound (b))
falls in a range of from 0.2 to 5.
142. A rechargeable lithium battery according to claim 81, wherein
the complexing agent (c) is used in such an amount that (the number
of moles of the complexing agent (c))/(the number of moles of the
metal compound (a)+the number of moles of the transition metal
compound (b)) falls in a range of from 1 to 5.
143. A rechargeable lithium battery according to claim 81, wherein
the completing agent (c) is used in such an amount that (the number
of moles of the complexing agent (c))/(the number of moles of the
metal compound (a)+the number of moles of the transition metal
compound (b)) falls in a range of from 2 to 5.
144. A rechargeable lithium battery according to claim 81, wherein
the reducing agent (e) is used in an amount which is 1 to 3 times
versus the sum of the equivalence point of the metal compound (a)
and that of the transition metal compound (b).
145. A rechargeable lithium battery according to claim 81, wherein
the reducing agent (e) is used in an amount which is 1 to 2 times
versus the sum of the equivalence point of the metal compound (a)
and that of the transition metal compound (b).
146. A rechargeable lithium battery according to claim 81, which
further includes a step of washing said amorphous alloy
material.
147. A rechargeable lithium battery according to claim 81, which
further includes a step of drying said amorphous alloy
material.
148. A rechargeable lithium battery according to claim 81, which
further includes a step of grinding said amorphous alloy material.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a process for producing an
electrode material which can be desirably used in the production of
a rechargeable lithium battery in which oxidation-reduction
reaction of lithium (comprising oxidation reaction of lithium and
reduction reaction of lithium ion) is used (this battery will be
hereinafter referred to as rechargeable lithium battery for
simplification purpose), an electrode structural body using said
electrode material, a rechargeable lithium battery whose electrode
comprising said electrode structural body, a process for producing
said electrode structural body, and a process for producing said
rechargeable lithium battery. More particularly, the present
invention relates to an electrode structural body for a
rechargeable lithium battery, which is constituted by an electrode
material comprising a specific amorphous alloy material capable of
being alloyed with lithium and which provides a high capacity and a
prolonged cycle life for said battery and to a rechargeable lithium
battery having an anode comprising said electrode structural body
and which has a high capacity and a prolonged cycle life. The
present invention includes a process for producing said electrode
structural body and a process for producing said rechargeable
lithium battery.
[0003] 2. Prior Art
[0004] In recent years, the global warming of the earth because of
the so-called greenhouse effect to an increase in the content of
CO.sub.2 gas in the air has been predicted. For instance, in
thermal electric power plants, thermal energy obtained by burning a
fossil fuel is converted into electric energy, and along with
burning of such fossil fuel, a large amount of CO.sub.2 gas is
exhausted in the air. Accordingly, in order to suppress this
situation, there is a tendency of prohibiting to newly establish a
thermal electric power plant. Under these circumstances, so-called
load leveling practice has been proposed in order to effectively
utilize electric powers generated by power generators in thermal
electric power plants or the like, wherein a surplus power unused
in the night is stored in rechargeable batteries installed at
general houses and the power thus stored is used in the daytime
when the demand for power is increased, whereby the power
consumption is leveled.
[0005] Now, for electric vehicles which do not exhaust anya'r
polluting substances such as CO.sub.2, NO.sub.x, hydrocarbons and
the like, there is an increased demand for developing a high
performance rechargeable battery with a high energy density which
can be effectively used therein. Besides, there is also an
increased demand for developing a miniature, lightweight, high
performance rechargeable battery usable as a power source for
portable instruments such as small personal computers, word
processors, video cameras, and cellular phones.
[0006] As such miniature, lightweight and high performance
rechargeable battery, there have proposed various rocking chair
type lithium ion batteries in which a carbonous material such as
graphite capable of intercalating lithium ion at intercalation
sites of its six-membered network plane provided by carbon atoms in
the battery reaction upon charging is used as an anode material and
a lithium intercalation compound capable of deintercalating said
lithium ion from the intercalation in the battery reaction upon
charging is used as a cathode material. Some of these lithium ion
batteries have been practically used. However, for any of these
lithium ion batteries whose anode comprising the carbonous material
(the graphite), the theoretical amount of lithium which can be
intercalated by the anode is only an amount of 1/6 per carbon atom.
Because of this, in such lithium ion battery, when the amount of
lithium intercalated by the anode comprising the carbonous material
(the graphite) is made greater than the theoretical amount upon
performing charging operation or when charging operation is
performed under condition of high electric current density, there
will be an unavoidable problem such that lithium is deposited in a
dendritic state (that is, in the form of a dendrite) on the surface
of the anode. This will result in causing internal-shorts between
the anode and the cathode upon repeating the charging and
discharging cycle. Therefore, it is difficult for the lithium ion
battery whose anode comprising the carbonous material (the
graphite) to achieve a sufficient charging and discharging cycle
life. In addition, using this battery design, it is extremely
difficult to attain a desirable rechargeable battery having a high
energy density comparable to that of a primary lithium battery in
which a metallic lithium is used as the anode active material.
[0007] Now, rechargeable lithium batteries in which a metallic
lithium is used as the anode have been proposed and they have
attracted public attention in a viewpoint that they exhibit a high
energy density. However, such rechargeable battery is not
practically usable one because its charging and discharging cycle
life is extremely short. A main reason why the charging and
discharging cycle life is extremely short has been generally
considered as will be described in the following. The metallic
lithium as the anode reacts with impurities such as moisture or an
organic solvent contained in an electrolyte solution to form an
insulating film or/and the metallic lithium as the anode has an
irregular surface with portions to which electric field is
converged, and these factors lead to generating a dendrite of
lithium upon repeating the charging and discharging cycle,
resulting in internal-shorts between the anode and cathode. As a
result, the charging and discharging cycle life of the rechargeable
battery is extremely shortened.
[0008] When the lithium dendrite is grown to make the anode and
cathode such that the anode is internally shorted with the cathode
as above described, the energy possessed by the battery is rapidly
consumed at the internally shorted portion. This situation often
creates problems in that the battery is heated or the solvent of
the electrolyte is decomposed by virtue of heat to generate gas,
resulting in an increase in the inner pressure of the battery.
Thus, the growth of the lithium dendrite tends to cause
internal-shorts between the anode and the cathode whereby occurring
such problems as above described, where the battery is damaged
or/and the lifetime of the battery is shortened.
[0009] In order to eliminate the above problems for such
rechargeable battery in which the metallic lithium is used as the
anode, specifically, in order to suppress the progress of the
reaction between the metallic lithium of the anode and the moisture
or the organic solvent contained in the electrolyte solution, there
has been proposed a method of using a lithium alloy such as a
lithium-aluminum alloy as the anode. However, this method is not
widely applicable in practice for the following reasons. The
lithium alloy is hard and is difficult to wind into a spiral form
and therefore, it is difficult to produce a spiral-wound
cylindrical rechargeable battery. Accordingly, it is difficult to
attain a rechargeable battery having a sufficiently long charging
and discharging cycle life. It is also difficult to attain a
rechargeable battery having a desirable energy density similar to
that of a primary battery in which a metallic lithium is used as
the anode.
[0010] Japanese Unexamined Patent Publications Nos. 64239/1996,
62464/1991, 12768/1990, 113366/1987, 15761/1987, 93866/1987, and
78434/1979 disclose various metals, i.e., Al, Cd, In, Sn, Sb, Pb,
and Bi which are capable of forming an alloy with lithium in a
rechargeable battery when the battery is subjected to charging, and
rechargeable batteries in which these metals, alloys of these
metals, or alloys of these metals with lithium are used as the
anodes. However, the above-mentioned publications do not detail
about the configurations of the anodes.
[0011] By the way, when any of the foregoing alloy materials is
fabricated into a plate-like form such as a foil form which is
generally adopted as an electrode of a rechargeable battery and it
is used as an anode of a rechargeable battery in which lithium is
used as the anode active material, the specific surface area of a
portion in the anode's electrode material layer contributing to the
battery reaction is relatively small and therefore, the charging
and discharging cycle is difficult to be effectively repeated with
a large electric current.
[0012] Further, for a rechargeable battery in which any of the
foregoing alloy materials is used the anode, there are such
problems as will be described in the following. The anode is
expanded with respect to the volume because of alloying with
lithium upon charging and shrunk upon discharging, where the anode
suffers from repetitive variations with respect the volume. Because
of this, the anode has a tendency that it is eventually distorted
and cracked. In the case where the anode becomes to be in such
state, when the charging and discharging cycle is repeated over a
long period of time, in the worst case, the anode is converted into
a pulverized state to have an increased impedance, resulting in
shortening the charging and discharging cycle life. Hence, none of
the rechargeable batteries disclosed in the above-mentioned
Japanese publications has been put to practical use.
[0013] In Extended Abstracts WED-2 (pages 69-72) of 8th
INTERNATIONAL MEETING ON LITHIUM BATTERIES (hereinafter referred to
as document 1), there is described that by electrochemically
depositing a Sn or a Sn-alloy on a copper wire having a diameter of
0.07 mm as a collector, an electrode having a deposited layer
comprising a grained tin material with a small particle size of 200
to 400 nm can be formed, and a cell in which the electrode having
such deposited layer with a thin thickness of about 3 .mu.m and a
counter electrode comprising a lithium metal are used has an
improved charging and discharging cycle life. Document 1 also
describes that in the evaluation wherein a cycle of operating
charging up to 1.7 Li/Sn (one atom of Sn is alloyed with 1.7 atoms
of Li) at a current density of 0.25 mA/cm.sup.2 and operating
discharging up to 0.9 V vs Li/Li.sup.+ is repeated, an electrode
comprising a fine-grained Sn material with a particle size of 200
to 400 nm, an electrode comprising a Sn.sub.0.91Ag.sub.0.09 alloy
and an electrode comprising a Sn.sub.0.72Sb.sub.0.28 alloy were
greater than an electrode comprising a coase-grained Sn alloy
material with a particle size of 2000 to 4000 nm deposited on a
collector comprising a copper wire having a diameter of 1.0 mm
obtained in the same manner as in the above, in terms of the
charging and discharging cycle life, respectively by about 4 times,
about 9 times, and about 11 times. However, the evaluated results
described in document 1 are of the case where the lithium metal was
used as the counter electrode and therefore, they are not evaluated
results obtained in practical battery configurations. In addition,
the foregoing electrodes are those prepared by depositing such
grained material as above described on the collector comprising a
copper wire having a diameter of 0.07 and therefore, any of them is
not of a practically usable electrode form. Further in addition,
according to the description of document 1, in the case where a Sn
alloy is deposited on a large area having a diameter of 1.0 mm for
example, it is understood that there is afforded an electrode
having a layer comprising a coarse-grained tin alloy material with
a particle size of 2000 to 4000 nm. However, for this electrode,
the lifetime as a battery will be extremely shortened.
[0014] Japanese Unexamined Patent Publications Nos. 190171/1993,
47381/1993, 114057/1988, and 13264/1988 disclose rechargeable
lithium batteries in which various lithium alloys are used as the
anodes. In these publications, there are described that these
rechargeable lithium batteries prevent deposition of lithium
dendrite and have an improved charging efficiency and an improved
charging and discharging cycle life. Japanese Unexamined Patent
Publication No. 234585/1993 discloses a rechargeable lithium
battery having an anode comprising a metal powder, which is
difficult to form an intermetallic compound with lithium, is
uniformly bonded on the surface of a lithium metal. In this
publication, it is described that this rechargeable lithium battery
prevents deposition of lithium dendrite and has an improved
charging efficiency and an improved charging and discharging cycle
life.
[0015] However, any of the anodes described in the above-mentioned
publications is not decisive one which can markedly prolong the
charging and discharging cycle life of the rechargeable lithium
battery.
[0016] Japanese Unexamined Patent Publication No. 13267/1988
discloses a rechargeable lithium battery in which a lithium alloy
obtained by electrochemically alloying an amorphous metal
comprising a plate-like aluminum alloy as a main example with
lithium is used as the anode. This publication describes that this
rechargeable lithium battery excels in charge-discharge
characteristics. However, according to the technique described in
this publication, it is difficult to realize a practically usable
rechargeable lithium battery having a high capacity and a charging
and discharging cycle life which falls in a practically usable
region.
[0017] Japanese Unexamined Patent Publication No. 223221/1998
discloses a rechargeable lithium battery in which a low crystalline
or amorphous intermetallic compound of an element selected from a
group consisting of Al, Ge, Pb, Si, Sn, and Zn is used as the
anode. This publication describes that this rechargeable lithium
battery has a high capacity and excels in cycle characteristics.
However, it is extremely difficult to industrially produce such low
crystalline or amorphous intermetallic compound in practice.
According to the technique described in this publication, it is
difficult to realize a practically usable rechargeable lithium
battery having a high capacity and a prolonged charging and
discharging cycle life.
[0018] By the way, Japanese Unexamined Patent Publication No.
317021/1998 discloses a method of chemically producing an amorphous
Co--Ni alloy using a reducing agent. However, this amorphous Co--Ni
alloy cannot be used as the electrode material in a rechargeable
lithium battery because it does not contain a metal capable of
being alloyed with lithium.
[0019] Japanese Unexamined Patent Publication No.78716/1993
discloses a process of chemically producing a metal powder using a
reducing agent comprising titanium trichloride. The present
inventors conducted experimental studies in that a plurality of
metal powders were prepared in accordance with the technique
described in this document, a plurality of rechargeable lithium
batteries were prepared using said metal powders as their anodes,
and the resultant rechargeable lithium batteries were evaluated
with respect to their battery characteristics. As a result, it was
found that any of the rechargeable lithium batteries does not have
a charging and discharging cycle life which falls in a practically
usable region. Thus, according to the technique described in this
document, it is difficult to realize a rechargeable lithium battery
having a charging and discharging cycle life which falls in a
practically usable region.
[0020] Further, Japanese Unexamined Patent Publication
No.329442/1999 discloses a lithium ion type non-aqueous
rechargeable battery in which at least either the cathode or the
anode contains a conductive material comprising a metal deposited
on the surface of a conductive material by a method of reducing a
metal ion. In this document, it is described that the rechargeable
battery excels in high rate discharging characteristics and cycle
performance. However, in this document, neither detailed
description nor discussion are made of amorphilization for the
conductive material constituting the electrode of the rechargeable
battery. Further, in this document, concrete grounds which
demonstrate that the rechargeable battery excels in cycle
performance are not detailed. Thus, it is difficult to recognize
that the rechargeable battery disclosed in this document is
satisfactory in terms of the charging and discharging cycle
life.
[0021] As above described, for the conventional rechargeable
lithium batteries in which oxidation-reduction reaction of lithium
is used, enlargement of their energy density and prolongation of
their charging and discharging cycle life are massive subjects to
be solved.
SUMMARY OF THE INVENTION
[0022] The present invention has been accomplished in view of the
foregoing situation in the prior art for rechargeable lithium
batteries in which oxidation-reduction reaction of lithium is
used.
[0023] An object of the present invention is to provide a process
for producing an electrode material comprising a specific amorphous
alloy material capable of being electrochemically alloyed with
lithium and which has excellent characteristics, and is suitable as
a constituent of an electrode of a rechargeable lithium battery
(that is, a rechargeable battery in which oxidation-reduction
reaction of lithium is used).
[0024] A typical embodiment of the electrode material-producing
process of the present invention comprises the steps of: (1) mixing
at least one kind of a metal compound (a) selected from a group
consisting of metal salts and metal complexes of a metal (a')
capable of being electrochemically alloyed with lithium, at least
one kind of a transition metal compound (b) selected from a group
consisting of transition metal salts and transition metal complexes
of a transition metal (b') and a complexing agent with a solvent to
obtain a mixed solution, (2) mixing a reducing agent with said
mixed solution to obtain a mixture, and (3) oxidizing said reducing
agent in said mixture to reduce ion of said metal (a') and ion of
said transition metal (b') whereby depositing an amorphous alloy
material (including an amorphous alloy particulate) capable of
being electrochemically alloyed with lithium which is usable as an
electrode material for a rechargeable lithium battery.
[0025] As a preferable example of said amorphous alloy material
produced according to the electrode material-producing process of
the present invention, there can be mentioned an amorphous alloy
material an (including an amorphous alloy particulate) containing a
Sn.A.X alloy with a substantially non-stoichiometric ratio
composition as a principal constituent. For the formula Sn.A.X, A
indicates at least one kind of an element selected from a group
consisting of transition metal elements, X indicates at least one
kind of an element selected from a group consisting of B, C, N, O
and S, where the element X is not always necessary to be contained.
The content of the constituent element Sn of the amorphous Sn.A.X
alloy has a relationship of Sn/(Sn+A+X)=20 to 80 atomic % in terms
of the number of atoms of each element (atom) of the entire
constituent elements Sn, A and X. The amorphous alloy material has
excellent characteristics and it is extremely suitable as a
constituent of an electrode, specifically, an anode of a
rechargeable lithium battery.
[0026] Another object of the present invention is to provide an
electrode structural body constituted by said electrode material
and which has a high capacity and a prolonged cycle life and is
usable as an electrode of a rechargeable lithium battery and a
process for producing said electrode structural body.
[0027] A further object of the present invention is to provide a
rechargeable lithium battery whose electrode comprising said
electrode structural body and which has a prolonged charging and
discharging cycle life and a high energy density and a process for
producing said rechargeable lithium battery.
BRIEF DESCRIPTION OF THE DRAWINGS
[0028] FIG. 1 is a schematic flow chart for explaining an
embodiment of a process for producing an electrode material for a
rechargeable lithium battery in the present invention.
[0029] FIG. 2 is a schematic cross-sectional view illustrating an
example of an apparatus used for practicing the process for
producing an electrode material in the present invention.
[0030] FIG. 3 is a schematic cross-sectional view illustrating
another example of an apparatus used for practicing the process for
producing an electrode material in the present invention.
[0031] FIG. 4 is a schematic cross-sectional view illustrating the
structure of an example of an electrode structural body according
to the present invention.
[0032] FIG. 5 is a schematic cross-sectional view illustrating a
basic constitution of an example of a rechargeable lithium battery
according to the present invention.
[0033] FIG. 6 is a schematic cross-sectional view illustrating an
example of a single-layer structure type flat battery according to
the present invention.
[0034] FIG. 7 is a schematic cross-sectional view illustrating an
example of a spiral-wound cylindrical battery according to the
present invention.
[0035] FIG. 8 shows X-ray diffraction charts of examples of
electrode materials obtained by the electrode material production
process of the present invention.
DESCRIPTION OF THE INVENTION AND PREFERRED EMBODIMENTS
[0036] As previously, described, the present invention provides a
process for producing an electrode material comprising a specific
amorphous alloy material capable of being alloyed with lithium and
which has excellent characteristics, and is suitable as a
constituent of an electrode of a rechargeable lithium battery.
[0037] The process typically comprises the steps of: (1) mixing at
least one kind of a metal compound (a) selected from a group
consisting of metal salts and metal complexes of a metal (a')
capable of being electrochemically alloyed with lithium, at least
one kind of a transition metal compound (b) selected from a group
consisting of transition metal salts and transition metal complexes
of a transition metal (b') and a complexing agent with a solvent to
obtain a mixed solution, (2) mixing a reducing agent with said
mixed solution to obtain a mixture, and (3) oxidizing said reducing
agent in said mixture to reduce ion of said metal (a') and ion of
said transition metal (b') whereby depositing an amorphous alloy
material capable of being electrochemically alloyed with lithium
which is usable as an electrode material for a rechargeable lithium
battery.
[0038] The present invention provides an electrode structural body
comprising an electrode material and a collector, characterized in
that said electrode material comprises said electrode material
produced by the above process and said collector comprises a
material incapable of being alloyed with lithium in electrochemical
reaction.
[0039] The electrode structural body has a high capacity and a
prolonged cycle life and is usable as an electrode of a
rechargeable lithium battery.
[0040] The present invention provides a process for producing said
electrode structural body, characterized by including a step of
arranging aforesaid electrode material produced by the above
electrode material-producing process on a collector comprising a
material incapable of being alloyed with lithium in electrochemical
reaction
[0041] The present invention provides a rechargeable lithium
battery comprising at least an anode, a cathode and an electrolyte
and in which oxidation-reduction reaction of lithium is used,
characterized in that said anode comprises aforesaid electrode
structural body.
[0042] The rechargeable lithium battery has a high energy density
and a prolonged charging and discharging cycle life.
[0043] The present invention provides a process for producing a
rechargeable lithium battery comprising at least an anode, a
cathode and an electrolyte and in which oxidation-reduction
reaction of lithium is used, characterized by including a step of
forming said anode using an electrode structural body formed by
arranging aforesaid electrode material produced by the above
electrode material-producing process on a collector comprising a
material incapable of being alloyed with lithium in electrochemical
reaction and a step of arranging said anode and said cathode to
oppose to each other through said electrolyte.
[0044] As above described, the process for producing an electrode
material for a rechargeable lithium battery in the present
invention comprises sequentially conducting a step (1) of mixing at
least one kind of a metal compound (a) selected from a group
consisting of metal salts and metal complexes of a metal (a')
capable of being electrochemically alloyed with lithium, at least
one kind of a transition metal compound (b) selected from a group
consisting of transition metal salts and transition metal complexes
of a transition metal (b') and a complexing agent (c) with a
solvent (d) to obtain a mixed solution, a step (2) of mixing a
reducing agent (e) with said mixed solution to obtain a mixture,
and a step (3) of oxidizing said reducing agent in said mixture to
reduce ion of said metal (a') and ion of said transition metal (b')
whereby depositing an amorphous alloy material (including an
amorphous alloy particulate) capable of being electrochemically
alloyed with lithium as said electrode material.
[0045] The amorphous alloy material is preferred to be an amorphous
metal-containing alloy material. And the amorphous alloy material
is preferred to have a peak appeared in a range of
2.theta.=20.degree. to 50.degree. in X-ray diffraction using
K.alpha.-rays of Cu as a radiation source, having a half width of
preferably more than 0.2.degree., more preferably more than
0.5.degree.. Further, the amorphous alloy material is preferred to
comprise a particulate having a crystallite size calculated from
X-ray diffraction analysis, which is preferably less than 50 nm,
more preferably less than 200 nm.
[0046] The metal (a') capable of being alloyed with lithium can
include Bi, In, Pb, Si, Ag, Sr, Ge, Zn, Sn, Cd, Sb, Tl, and Hg. Of
these, Bi, In, Pb, Zn, Sn, Sb, and Tl are preferred, and Sn is more
preferred. The metal (a') may comprise one or more of these
metals.
[0047] The transition metal (b') can include Cr, Mn, Fe, Co, Ni,
Cu, Mo, Tc, Ru, Rh, Pd, Ag, Os, Ir, Pt, Au, Ti, V, Y, Sc, Zr, Nb,
Hf, Ta, and W. Of these, Cr, Mn, Fe, Co, Ni, Cu, Ru, Rh, Pd, Ag,
Os, Ir, Pt, and Au are preferred, and Cr, Mn, Fe, Co, Ni, and Cu
are more preferred. The transition metal (b') may comprise one or
more of these transition metals.
[0048] In a preferred embodiment, the amorphous alloy material is
preferred to comprise an amorphous alloy material (including an
amorphous alloy particulate) containing a Sn.A.X alloy with a
substantially non-stoichiometric ratio composition. For the formula
Sn.A.X, A indicates at least one kind of an element selected from a
group consisting of transition metal elements, X indicates at least
one kind of an element selected from a group consisting of B, C, N,
O and S, where the element X is not always necessary to be
contained. The content of the constituent element Sn of the
amorphous Sn.A.X alloy is preferred to have a relationship of
Sn/(Sn+A+X)=20 to 80 atomic % in terms of the number of atoms of
each element (atom) of the entire constituent elements Sn, A and
X.
[0049] The amorphous Sn.A.X alloy in the present invention is
preferred to have a peak appeared in a range of 2.theta.=20.degree.
to 50.degree. in X-ray diffraction using K .alpha.-rays of Cu as a
radiation source, having a half width of preferably more than
0.2.degree., more preferably more than 0.5.degree..
[0050] The above amorphous alloy material is preferred to comprise
a particulate having a crystallite size calculated from X-ray
diffraction analysis, which is preferably less than 50 nm, more
preferably less than 20 nm. In addition, the amorphous alloy
material is preferred to have an average particle size which is
preferably in a range of from 0.1 .mu.m to 2 .mu.m, more preferably
in a range of from 0.1 .mu.m to 1 .mu.m. Further in addition, the
amorphous alloy material is preferred to have a specific surface
area of preferably more than 10 m.sup.2/g, more preferably more
than 30 m.sup.2/g.
[0051] The metal compound (a) used in the present invention is
preferred to be soluble in the solvent (d). As specific preferable
examples of the metal compound (a), there can be mentioned
chlorides, sulfates and nitrates of those metals capable of being
alloyed with lithium which are illustrated as the metal (a') in the
above. Of these, chlorides, sulfates and nitrates of Sn are more
preferable. In the present invention, these compounds can be used
either singly or in combination of two or more of them as the
compound (a).
[0052] Similarly, the transition metal compound (b) used in the
present invention is preferred to be soluble in the solvent (d). As
specific preferable examples of the transition metal compound (b),
there can be mentioned chlorides, sulfates and nitrates of those
transition metals capable of being alloyed with lithium which are
illustrated as the transition mental (b') in the above. In the
present invention, these compounds can be used either singly or in
combination of two or more of them as the compound (b).
[0053] The complexing agent (c) used in the present invention can
include organic carboxylic acids and amines. As specific preferable
examples of the complexing agent (c), there can be mentioned citric
acids, ethylenediaminetetraacetic acid, and salts of these acids.
In the present invention, these compounds can be used either singly
or in combination of two or more of them as the complexing agent
(c).
[0054] The reducing agent (e) used in the present invention is
preferred to comprise a material having an electrode potential
which is inferior by more than 0.1 V or preferably more than 0.2 V
to that of the metal (a') or the transition metal (b') which is the
lowest. In addition, said material as the reducing agent (e) is
preferred to be such that an aqueous solution of said material
maintained at 25.degree. C. has a normal electrode potential of
less than -0.2 V or preferably less than -0.5 V. Further, said
material as the reducing agent (e) is preferred to be soluble in
the solvent (d).
[0055] Such material which can satisfy these conditions as the
reducing agent (e) can include lower oxygen compounds such as
hypophosphorous acid, phosphorous acid, sulfurous acid,
thiosulfuric acid, and dithionous acid; salts of these compounds;
metal salts in the low valence state of Fe (II), Ti (III) and Cr
(II); organic compounds such as formaldehyde, formic acid, and
oxalic acid; and salts of these organic compounds. In the present
invention, these compounds can be used either singly or in
combination of two or more of them as the reducing agent (e).
[0056] The solvent (d) used in the present invention can include
water and polar solvents. Specifically, the solvent (d) may
comprise at least one kind of a material selected from a group
consisting of water, alcohols, ester compounds, amide compounds,
nitrile compounds, amine compounds, halogen compounds, sulfur
compounds, liquid ammonia, and glacial acetic acid. The solvent (d)
is preferred to comprise at least one kind of a material selected
from a group consisting of water and alcohols.
[0057] The step (2) of mixing the foregoing mixed solution with the
reducing agent (e) is preferred to perform under condition with a
temperature in a range of -10 to 100.degree. C. or preferably in a
range of 10 to 90.degree. C. Further, the step (2) is preferred to
perform in an atmosphere composed of at least one kind of a gas
selected from hydrogen gas, nitrogen gas, and inert gas such as
argon gas or helium gas.
[0058] The step (3) of oxidizing the reducing agent (e) in the
foregoing mixture is preferred to perform under condition with a
temperature in a range of -10 to 100.degree. C. or preferably in a
range of 10 to 90.degree. C. In addition, the step (3) is preferred
to perform in an atmosphere composed of at least one kind of a gas
selected from hydrogen gas, nitrogen gas, and inert gas such as
argon gas or helium gas.
[0059] Further, the step (3) is preferred to perform by adjusting
the solution of the mixture to have a pH value in a range of 3 to
12 or preferably in a range of 5 to 10.
[0060] To adjust the solution of the mixture to have said pH value
may be conducted by adding an alkali. The addition of the alkali is
preferred to perform so that the pH value of the solution of the
mixture is changed from 2 or less to a range of 3 to 12 or
preferably to a range of 5 to 10.
[0061] The alkali added can include hydroxides of alkali metals,
hydroxides of alkaline earth metals, amines, and ammonia. These
compounds can be used either singly or in combination of two or
more of them.
[0062] The step of oxidizing the reducing agent (e) in the mixture
may be performed concurrently at the time of mixing the mixed
solution with the reducing agent (e) in the step (2) in which the
mixed solution is mixed with the reducing agent.
[0063] The amount of the metal compound (a) to be added and that of
the transition metal compound (b) to be added are preferred to be
made such that [the number of moles of the metal (a') in the
compound (a)]/[the number of moles of the transition metal (b') in
the transition metal compound (b)] becomes to be in a range of 0.1
to 10 or preferably in a range of 0.2 to 5.
[0064] The amount of the complexing agent (c) to be added is
preferred to be made such that [the number of moles of the
complexing agent (c)]/[the number of moles of the metal compound
(a)+the number of moles of the transition metal compound (b)]
becomes to be in a range of 1 to 5 or preferably in a range of 2 to
5.
[0065] The amount of the reducing agent (e) to be added is
preferred to be made such that the amount of the reducing agent (e)
added becomes 1 to 3 times or preferably 1 to 2 times the sum of
the oxidation-reduction equivalence point of the metal compound (a)
and that of the transition metal compound (b) in terms of the
equivalence ratio.
[0066] The above-described electrode material-producing process is
possible to include a step of washing the foregoing alloy material
as the electrode material. The process is also possible to include
a step of drying the washed alloy material. The process is further
possible to include a step of grinding the dried alloy
material.
[0067] As previously described, the present invention provides an
electrode structural body comprising an electrode material and a
collector, characterized in that said electrode material comprises
a given amorphous alloy material produced by the foregoing
electrode material-producing process and said electrode comprises
an material incapable of being alloyed in the electrochemical
reaction. In this case, it is possible that the amorphous alloy as
the electrode material is formed in a layer form on the
collector.
[0068] The electrode structural body may be an electrode structural
body comprising an electrode material layer formed using aforesaid
amorphous alloy as the electrode material and a binder, and
aforesaid collector. The binder in this case may comprise a
water-soluble organic polymer material.
[0069] The electrode structural body may be an electrode structural
body comprising an electrode material layer formed using aforesaid
amorphous alloy as the electrode material, aforesaid binder, and an
electrically conductive auxiliary, and aforesaid collector.
[0070] The present invention provides a process for producing an
electrode structural body, characterized by including a step of
arranging a given amorphous alloy material as the electrode
material produced by the foregoing electrode material-producing
process on a collector comprising a material incapable of being
alloyed with lithium in the electrochemical reaction. The process
is possible to include a step of forming said amorphous alloy
material in a layer form on said collector by way of press forming.
The process is also possible to include a step of mixing said
amorphous alloy material with a binder and if necessary, a solvent
to obtain a paste-like product and arranging said paste-like
product on said collector.
[0071] The present invention provides a rechargeable lithium
battery comprising at least an anode, a cathode and an electrolyte
and in which oxidation-reduction reaction of lithium is used,
characterized in that said anode comprises aforesaid electrode
structural body. In this case, it is desired for the cathode to
chiefly comprise a lithium-containing electrode material.
[0072] The present invention provides a producing a rechargeable
lithium battery comprising at least an anode, a cathode and an
electrolyte and in which oxidation-reduction reaction of lithium is
used, characterized by including a step of forming said anode using
an electrode structural body formed by arranging an given amorphous
alloy material as the electrode material produced by the foregoing
electrode material-producing process on a collector comprising a
material incapable of being alloyed with lithium in electrochemical
reaction and a step of arranging said anode and said cathode to
oppose to each other through said electrolyte. The cathode is
preferred to chiefly comprise a lithium-containing electrode
material.
[0073] The anode-forming step may be conducted by forming said
amorphous alloy material in a layer form on said collector by way
of press forming. Alternatively, the anode-forming step may be
conducted by mixing said amorphous alloy material with a binder and
if necessary, a solvent to obtain a paste-like product and
arranging said paste-like product on said collector.
[0074] By the way, the present invention has been accomplished on
the basis of the following finding obtained through experimental
studies by the present invention. That is, the present inventors
created a process which enables one to produce an amorphous alloy
material capable of being electrochemically alloyed with lithium
and which has excellent characteristics, and is suitable as a
constituent of an electrode of a rechargeable lithium battery in
which oxidation-reduction reaction of lithium is used.
Particularly, the process comprises the steps of: mixing at least
one kind of a metal compound (a) selected from a group consisting
of metal salts and metal complexes of a metal (a') capable of being
electrochemically alloyed with lithium, at least one kind of a
transition metal compound (b) selected from a group consisting of
transition metal salts and transition metal complexes of a
transition metal (b') and a complexing agent with a solvent to
obtain a mixed solution; mixing a reducing agent with said mixed
solution to obtain a mixture; and oxidizing said reducing agent in
said mixture to reduce ion of said metal (a') and ion of said
transition metal (b') whereby depositing an amorphous alloy
material capable of being electrochemically alloyed with
lithium.
[0075] A variety of amorphous alloy materials were prepared by this
process. Using these amorphous alloy materials as electrode
materials, there were prepared a plurality of electrode structural
bodies respectively usable as an anode of a rechargeable lithium
battery. Using these electrode structural bodies, there were
prepared a plurality of rechargeable lithium batteries. And the
resultant rechargeable lithium batteries were evaluated with
respect to their battery characteristics. As a result, any of the
rechargeable lithium batteries was found to have a high capacity
and a prolonged cycle life (a prolonged charging and discharging
cycle life).
[0076] For the reason why such rechargeable lithium battery whose
anode comprising an electrode structural body formed using the
electrode material comprising aforesaid amorphous alloy material
has a high capacity and a prolonged cycle life, it is considered as
will be described below.
[0077] In the system in which the metal compound capable of being
electrochemically alloyed with lithium and the transition metal
compound are together present, by performing reduction by the
reducing agent, there are afforded an alloy comprising a metal
capable of being alloyed with lithium and a transition metal. That
is, as shown in the following equations, metal ion M.sup.+ capable
of being alloyed with lithium in the oxidized state and transition
metal ion A.sup.+ are reduced by the reducing agent R (where the
reducing agent itself is oxidized) to form an alloy MA.
M.sup.++A.sup.++R.fwdarw.MA+R.sup.2+
M.sup.++A.sup.++R.fwdarw.MA+R.sup.3+
[0078] (where M.sup.+ indicates metal ion of the metal capable of
being alloyed with lithium, A.sup.+ indicates metal ion of the
transition metal, each of R and R.sup.+ indicates the reducing
agent, and the mark ".sup.+" indicates an oxidation number.)
Specifically, for instance, as shown in the following
equations;
Sn.sup.2++Ni.sup.2++Ti.fwdarw.SnNi+Ti.sup.4+
Sn.sup.2++Ni.sup.2++4Ti.sup.3+.fwdarw.SnNi+4 Ti.sup.4+
[0079] Sn ion and Ni ion are reduced to form an alloy comprising Sn
and Ni. At this time, when the formation of the alloy is performed
in a solvent, the respective metal ions are reduced into metals
from the uniformly mixed state in the solvent. Because of this, the
homogeneousness of the alloy formed is improved. This alloy is
formed from the metal elements which are different with respect to
their atomic radius (preferably more than 10%, more preferably more
than 12%). Therefore, it is considered that distortion is liable to
occur in the formation of an alloy crystal, and thus, an amorphous
portion is likely to readily form. In addition, at the time when
reduced metal elements are bonded to form a crystal, it is
considered that the solvent molecular hinders the formation of the
crystal, and as a result, distortion is liable to occur in the
formation of the alloy crystal, and thus, an amorphous portion is
likely to readily form.
[0080] Now, in accordance with the foregoing process, there can be
obtained an amorphous alloy particulate containing amorphous phase
which has a short distance order property but does not have a
long-distance order property. The amorphous alloy particulate does
not have a large change in the crystalline structure when it is
alloyed with lithium, and therefore, the volume expansion is small.
In this connection, when the amorphous alloy particulate is used in
the anode of a rechargeable lithium battery, the electrode material
layer of the anode is slightly expanded or shrunk upon charging or
discharging. Thus, there can be attained a rechargeable lithium
battery whose anode is hardly cracked or ruptured even when the
charging and discharging cycle is repeated over a long period of
time, where the performance thereof is maintained without being
deteriorated.
[0081] Separately, by using the complexing agent in the reaction
system, it is possible that the metal compounds form complexes and
they are stably and uniformly present in the solvent without being
aggregated. Because of this, it is considered that the
homogeneousness of the alloy formed is more improved and the
amorphization is more facilitated.
[0082] In the following, description in more detail will be made of
the process for producing an electrode material in the present
invention.
[0083] The production process basically comprises mixing a
prescribed reducing agent with a mixed solution which contains a
prescribed metal compound containing a metal capable of being
alloyed with lithium, a prescribed transition metal compound, and a
prescribed complexing agent, and oxidizing said reducing agent to
reduce ion of the metal capable of being alloyed with lithium and
ion of the transition metal whereby synthesizing an amorphous alloy
material.
[0084] Preferred embodiments of the production process will be
detailed with reference to FIGS. 1 to 3.
[0085] FIG. 1 is a schematic flow chart for explaining an
embodiment of the production process. FIG. 2 is a schematic
cross-sectional view illustrating an example of a fabrication
apparatus used for practicing the production process. FIG. 3 is a
schematic cross-sectional view illustrating another example of a
fabrication apparatus used for practicing the production
process.
[0086] The fabrication apparatus shown in FIG. 2 is a batch type
fabrication apparatus in which all the steps from the introduction
of starting materials to the termination of the reaction treatment
are performed in the same reaction vessel. The fabrication
apparatus shown in FIG. 2 comprises a reaction vessel 201 provided
with an starting material introduction device 202, a reflux device
203, a gas introduction pipe 204, an agitator 205, and a
temperature controlling equipment 206.
[0087] The fabrication apparatus shown in FIG. 3 is a continuous
fabrication apparatus in which the respective steps are
individually performed in separate vessels.
[0088] The fabrication apparatus shown in FIG. 3 comprises a
starting material addition vessel 302, a reducing agent addition
vessel 303, a mixing vessel 304, an addition vessel 308, a reaction
vessel 301, and a product recovery vessel 309. The respective
vessels are communicated with each other through connection pipes
307 having a flow rate regulating valve 307 such that a flow from
each of the starting material addition vessel 302 and the reducing
agent addition vessel 303 is flown into the mixing vessel 304,
followed by being flown into the reaction vessel 301; a flow from
the addition vessel 308 is flown into the reaction vessel 301, and
a flow from the reaction vessel 301 is flown into the product
recovery vessel 309. Each of the vessels 301, 302, 303, 304, and
308 is provided with an agitator 305. And each of the vessels 301,
302, 303, 304, 308 and 309 is provided with a temperature
controlling equipment 306.
[0089] The production process in the fabrication apparatus shown in
FIG. 2 will be explained while referring to FIG. 1.
[0090] In the fabrication apparatus shown in FIG. 2, first, inert
gas such as nitrogen gas is introduced into the reaction vessel 201
through the gas introduction pipe 204, where only excessive gas is
exhausted outside the system through the ref lux device 203. Then,
at least one kind of a metal compound (a) selected from a group
consisting of metal salts and metal complexes of a metal (a')
capable of being electrochemically alloyed with lithium, at least
one kind of a transition metal compound (b) selected from a group
consisting of transition metal salts and transition metal complexes
of a transition metal (b'), a complexing agent (c) and a solvent
(d) are introduced into the reaction vessel 201 through the
starting material introduction device 202, followed by being
stirred by means of the agitator 205 (see, step A in FIG. 1), where
a reducing agent (e) is introduced there through the starting
material introduction device 202 (see, step C in FIG. 1). The
temperature of the mixed solution in the reaction vessel 201 is
controlled to a prescribed temperature by means of the temperature
controlling equipment 206.
[0091] Thereafter, if necessary in order to oxidize the reducing
agent in the mixed solution, by adding a pH-adjusting agent
comprising an alkali or the like (see, step C in FIG. 1), the
reducing agent in the mixed solution is oxidized (see, step D in
FIG. 1), and reduction reaction of the metal compound (a) and the
transition metal compound (b) is progressed. After the termination
of the reaction, a synthesized product is washed and dried (see,
steps E and F in FIG. 1). In this way, there is obtained an
amorphous alloy material as an electrode material.
[0092] The production process in the continuous fabrication
apparatus shown in FIG. 3 will be explained while referring to FIG.
1.
[0093] In the continuous fabrication apparatus shown in FIG. 3,
first, the entire inside atmosphere is replaced by inert gas such
as nitrogen gas or the like. Then, at least one kind of a metal
compound (a) selected from a group consisting of metal salts and
metal complexes of a metal (a') capable of being electrochemically
alloyed with lithium, at least one kind of a transition metal
compound (b) selected from a group consisting of transition metal
salts and transition metal complexes of a transition metal (b'), a
complexing agent (c) and a solvent (d) are introduced into the
starting material addition vessel 302, followed by being stirred by
means of the agitator 305 (see, step A in FIG. 1), and the mixture
in the starting material addition vessel 302 is introduced into the
mixing vessel 304 while adjusting the amount of the mixture to be
added by means of the flow rate regulating valve 307, and a
reducing agent (e) introduced into the reducing agent addition
vessel 303 is introduced into the mixing vessel 304 while adjusting
the amount of the reducing agent to be added by means of the flow
rate regulating valve 307, where the contents in the mixing vessel
304 are stirred and well-mixed by means of the agitator 305 (see,
step C in FIG. 1). The temperature of the mixed solution in the
mixing vessel 304 is controlled to a prescribed temperature by
means of the temperature controlling equipment 306. The mixed
solution in the mixing vessel 304 is introduced into the reaction
vessel 301 while adjusting the amount of the mixed solution to be
added by means of the flow rate regulating valve 307, and if
necessary in order to oxidize the reducing agent in the mixed
solution, by introducing a pH-adjusting agent comprising an alkali
or the like into the reaction vessel 301 from the addition vessel
308 while adjusting the amount of the pH-adjusting agent to be
added by means of the flow rate regulating valve 307, the reducing
agent in the mixed solution is oxidized (see, step D in FIG. 1),
and reduction reaction of the metal compound (a) and the transition
metal compound (b) is progressed. The temperature of the reaction
solution in the reaction vessel 301 is controlled to a prescribed
temperature by means of the temperature controlling equipment 306,
followed by being introduced into the product recovery vessel 309,
where the reaction solution in the product recovery vessel 309 is
cooled to a prescribed temperature, whereby a synthesized product
is afforded in the product recovery vessel 309. The synthesized
product is taken out from the product recovery vessel 309, and it
is washed and dried (see, steps E and F in FIG. 1). In this way,
there is obtained an amorphous alloy material as an electrode
material.
[0094] The resultant amorphous alloy material as the electrode
material may be ground by means of a grinding apparatus such as a
ball mill or the like.
[0095] The production process which is practiced by using the
continuous fabrication apparatus shown in FIG. 3 is more
advantageous in comparison with the production process which is
practiced by using the batch type fabrication apparatus shown in
FIG. 2, in that in the former, (i) the separation of a product from
the starting materials remained without being reacted can be
readily conducted and the product can be obtained in a state with
little impurity, (ii) the reaction time can be readily adjusted as
desired by means of the flow rate regulating valve, and (iii) the
temperature of the starting materials, the reaction temperature and
the temperature of a product can be individually controlled, and
(iv) particularly in the case of producing an electrode material in
a large amount, a stable and homogeneous product as the electrode
material can be continuously produced.
[0096] Now, in the electrode material-producing process of the
present invention, at the time of adding the reducing agent, (see,
step C in FIG. 1) and also at the time of oxidizing the reducing
agent (see, step D in FIG. 1), to maintain the temperature of the
mixed solution in the reaction vessel to be constant at a
prescribed temperature by heating or cooling the reaction vessel is
preferred because decomposition reaction or side reaction of the
reducing agent due to heat of the mixing or heat of the reaction is
difficult to occur. Specifically, it is desired that the
temperature of the mixed solution in the reaction vessel is
maintained at a temperature preferably in a range of from -10 to
100.degree. C. or more preferably in a range of from 10 to
90.degree. C. When the temperature of the mixed solution in the
reaction vessel is maintained at a temperature of less than
-10.degree. C., there is a tendency in that the extent of an
amorphous portion (phase) formed in a product is decreased. When
the temperature of the mixed solution in the reaction vessel is
maintained at a temperature of beyond 100.degree. C., there is a
tendency in that impurity in a relatively large amount is occurred
and it gets in a product obtained.
[0097] In addition, at the time of adding the reducing agent (see,
step C in FIG. 1), it is preferred to control the temperature of
the reducing agent to be the same as that of the mixed solution in
the reaction vessel in order to decrease a change in the
temperature of the mixed solution in the reaction vessel when the
reducing agent is added to and mixed with the mixed solution.
[0098] As the gas which is introduced into the reaction vessel, it
is possible to use hydrogen gas and inert gas such as argon gas or
helium gas other than nitrogen gas. In this case, there is an
advantage in that the reducing agent is maintained without being
oxidized with said gas. Further, it is preferred that the
introduction of said gas into the reaction vessel is continued from
the step of introducing the metal compound (a) and the transition
metal compound (b) into the reaction vessel (see, step A in FIG. 1)
until the step of oxidizing the reducing agent (see, step D in FIG.
1). In this case, gas and the like generated by the reaction in the
reaction chamber are exhausted outside the system and as a result,
impurity is refrained from generating in the reaction vessel.
[0099] Particularly, when formaldehyde or formic acid is used as
the reducing agent, carbon dioxide is liable to generate, and when
sodium thiosulfate is used as the reducing agent, sulfur dioxide is
liable to generate; and when such gas is generated, impurity such
as carbonate substance or sulfate substance is likely to generate.
However, such impurity is refrained from generating.
[0100] Further, at the time of adding the reducing agent (see, step
C in FIG. 1), it is preferred that when the reducing agent
comprises a solid or gaseous material, said material is dissolved
in a solvent which is the same as the solvent used in the reaction
prior to adding it (see, step B in FIG. 1). In the case where the
reducing agent comprises a liquid material, said liquid material
can be added as it is (see, step B in FIG. 1).
[0101] For the amount of the reducing agent to be added (see, step
C in FIG. C), it is sufficient to add a given material as the
reducing agent in an amount which is corresponding to an
equivalence point with respect to a change in the oxidation number
per mole of said material as the reducing agent (the number of
electron released) and a change in the oxidation number per mole of
the metal which is to be reduced (the number of electron released,
i.e., the number of electrons entrapped). However, the reducing
agent in an excessive amount is preferred to be added because the
yield is increased in this case.
[0102] The amount corresponding to the equivalence point here is
meant that for instance, in the case where the reducing agent is
oxidized such that the oxidation number is changed from +3 to +4
and the metal in the metal compound to be reduced is reduced such
that the oxidation number is changed from +2 to 0, the reducing
agent in an amount which is corresponding to 2 times the amount of
the metal compound in terms of the mole ratio is added.
[0103] Even when the oxidation number of the metal compound (a)
containing the metal capable of being alloyed with lithium is
different from that of the transition metal (b), it is sufficient
to add the reducing agent in an amount corresponding to the sum of
the equivalence point of the metal compound (a) and that of the
transition metal compound (b). In a preferred embodiment, in view
of increasing the yield while preventing the generation of
impurity, the amount of the reducing agent to be added is
preferably 1 to 3 times or more preferably 1 to 2 times
respectively versus the sum of the equivalence point of the metal
compound (a) and that of the transition metal compound (b).
[0104] In the case where the reducing agent has a large oxidation
power and it sufficiently reacts with the metal compound merely by
mixing it with the metal compound, it is preferred to hasten the
addition speed of the reducing agent at the time of adding the
reducing agent (see, step C in FIG. 1), because in this case, the
reaction in the mixed solution is rapidly progressed, where an
alloy crystal is hardly formed and the amorphization is desirably
progressed. That is, it is desired that generation reaction of an
alloy is terminated within a short period of time. For the addition
speed of the reducing agent, it is desired that the addition of the
entire amount of the reducing agent is terminated preferably within
2 minutes or more preferably within 1 minute.
[0105] For the use amount of the metal compound (a) and that of the
transition metal compound (b) to be used, they are preferred to be
made such that [the number of moles of the metal (a') (capable of
being alloyed with lithium) in the metal compound (a)]/[the number
of moles of the transition metal in the transition metal compound
(b)] is preferably in a range of from 0.1 to 10 or more preferably
in a range of from 0.2 to 5. In the case where the relationship
between the use amount of the metal compound (a) and that of the
transition metal compound (b) is outside the above range, there is
a tendency that the amorphous portion (phase) occurred in a product
as an electrode material is diminished.
[0106] Separately, it is possible to use an appropriate compound or
the like other than the metal compound (a) and that of the
transition metal compound (b) so that a product obtained as an
electrode material contains its constituent. In this case, it is
possible that said compound is introduced into the reaction vessel
together with the metal compound (a) and that of the transition
metal compound (b) when the metal compound (a) and that of the
transition metal compound (b) are introduced into the reaction
vessel (see, step A in FIG. 1).
[0107] For the amount of the complexing agent (c) to be added, it
is desired to be made such that [the number of moles of the
complexing agent]/[the number of moles of the metal compound
(a)+the number of moles of the transition metal compound (b)] is
preferably in a range of from 1 to 5 or more preferably in a range
of from 2 to 5.
[0108] When the complexing agent in an amount which falls in the
above range is used, the metal ion of the metal compound (a) and
that of the transition metal compound (b) are stably and uniformly
dissolved in the solvent (d) and as a result, the occurrence of
impurity is diminished, where a product with good amorphization as
an electrode material can be obtained.
[0109] For the use amount of the solvent (d), it is desired in such
an amount that the metal compound (a), the transition metal
compound (b), the complexing agent (c) and the reducing agent (e)
which are mixed with the solvent are uniformly dispersed in the
solvent while being dissolved therein. However, in the case where
the mixed solution whose solvent is excessive and which is
therefore thin in terms of the concentration, the reduction
reaction becomes gentle and therefore, the yield of a product (a
synthesized product) is decreased. In this respect, the use amount
of the solvent is preferred to be adjusted so that the weight molar
concentration of the reducing agent (e) becomes to fall preferably
in a range of from 0.1 to 5 mole/Kg or more preferably in a range
of from 0.5 to 4 mole/Kg.
[0110] At the time when the metal compound (a), the transition
metal compound (b), and the complexing agent (c) are mixed with the
solvent (d) (see, step A in FIG. 1), these materials may be
entirely mixed with the solvent at the same time. Alternatively, it
is possible that they are intermittently mixed with the solvent
several times. In this case, it is possible that each of the metal
compound (a), the transition metal compound (b), and the complexing
agent (c) is individually mixed with the solvent and they are
together mixed.
[0111] Separately, at the time when the metal compound (a), the
transition metal compound (b), and the complexing agent (c) are
mixed with the solvent (d) (see, step A in FIG. 1), it is possible
to add a dispersant comprising a surface active agent selected from
a group consisting of an anionic surface active agent, a cationic
surface active agent, and a nonionic surface active agent. In this
case, the homogeneousness of the mixed solution is improved.
[0112] At the time when the oxidation is performed by adding the
reducing agent (see, steps C and D in FIG. 1), to maintain the
mixed solution (the reaction solution) to be constant at a
prescribed pH value is preferred for the reason that a complex
formed by the metal ions and the complexing agent is stabilized.
Specifically, it is preferred that the pH value of the mixed
solution is made to be preferably in a range of from 3 to 12 or
more preferably in a range of from 5 to 10. When the pH value of
the mixed solution is less than 3, the yield of a product as an
electrode material is diminished. When the pH value of the mixed
solution is beyond 12, there is a tendency in that impurity is
increased.
[0113] To adjust the pH value of the mixed solution in the above
range may be performed by adding an acid or an alkali to the mixed
solution or by adding a pH buffer to the mixed solution.
[0114] When the reducing agent comprises, for instance, titanium
trichloride which is highly reactive and is likely to become
unstable when the pH value of the mixed solution is in the above
range, it is considered to take a manner in that in step C (see,
FIG. 1), the reducing agent is added to the mixed solution which is
maintained at a pH value where the reducing agent is stabilized,
and in step D (see, FIG. 1), by adding an alkali or an acid to the
mixed solution, the reducing agent is oxidized and simultaneously
with this, the pH value of the reaction solution is controlled to
fall in the above range. But this manner is not always effective
because in the high pH value region (the alkaline region), the
metal ions of the metal compound (a) and the transition metal
compound (b) form hydroxides and they are precipitated. Therefore,
it is preferred to control the pH value of the mixed solution (the
reaction solution) to fall in the above range by adding an alkali
from the low pH value region (the acidic region).
[0115] In this case, in view of the stability of the reducing agent
in step C (see, FIG. 1), it is preferred to make the pH vale of the
low pH value region to be 2 or less.
[0116] In addition, it is preferred to hasten the speed of adding
the alkali because in this case, the reduction reaction in the
mixed solution is rapidly occurred and as a result, an alloy
crystal is hardly formed and the amorphization is desirably
progressed.
[0117] The above situation can be understood with reference to
X-ray diffraction charts shown in FIG. 8.
[0118] FIG. 8(1) shows an X-ray diffraction chart of an amorphous
alloy material obtained by quickly adding an alkali for 30 seconds
in Example 1 which will be described later. FIG. 8(2) shows an
X-ray diffraction chart of an amorphous alloy material obtained in
the same manner as in Example 1 except for slowly adding the alkali
for 15 minutes.
[0119] In comparison of the X-ray diffraction chart shown in FIG.
8(1) with the X-ray diffraction chart shown in FIG. 8(2), it is
understood that the amorphization in the latter is not progressed
as that in the former.
[0120] That is, it is preferred that the generation reaction of an
alloy is terminated within a short period of time and that the
addition of the total amount of the alkali is completed preferably
for less than 2 minutes or more preferably for less than 1
minute.
[0121] Specific preferable examples of the alkali to be added are
hydroxides of alkali metals, hydroxides of alkaline earth metals,
amines, and ammonia.
[0122] The method adopted for oxidizing the reducing agent is
different depending upon the oxidation power of the reducing agent
(that is, a difference between the electrode potential of the
reducing agent and that of the metal ion to be reduced)[which will
be described later in the item of reducing agent]. However, as
specific examples of the method for oxidizing the reducing agent,
there can be mentioned a method in that any of the foregoing
alkalis is added to a mixed solution containing a given reducing
agent, given metal ion capable of being alloyed with lithium, and
given transition metal ion to adjust the pH value of said mixed
solution whereby oxidizing the reducing agent contained in the
mixed solution; a method in that a given reducing agent is admixed
in a mixed solution containing a given reducing agent, given metal
ion capable of being alloyed with lithium, and given transition
metal ion, followed by subjecting to a heat treatment, whereby the
reducing agent in the mixed solution is oxidized; a method in that
a given reducing agent is heated, a mixed solution containing a
given reducing agent, given metal ion capable of being alloyed with
lithium, and given transition metal ion is also heated, and the
heated reducing agent is admixed in the heated mixed solution,
whereby the reducing agent in the mixed solution is oxidized; and a
method in that when a given reducing agent having a strong
oxidation power and which is liable to rapidly cause reaction is
used, after the reducing agent is cooled, the reducing agent is
admixed in a mixed solution containing a given reducing agent,
given metal ion capable of being alloyed with lithium, and given
transition metal ion, whereby the reducing agent in the mixed
solution is oxidized.
[0123] Now, the temperature of the mixed solution in the reaction
vessel is preferred to be controlled by cooling or heating the
mixed solution so as to fall preferably in a range of from -10 to
100.degree. C. or more preferably in a range of from 10 to
90.degree. C.
[0124] In the following, description will be made each starting
material used in the process for producing an electrode
material.
[0125] Metal Compound (a):
[0126] The metal compound (a) includes metal salts and metal
complexes of a metal (a') capable of being alloyed with lithium.
These metal salts and metal complexes are soluble in the solvent
(d).
[0127] The metal (a') can include Bi, In, Pb, Si, Ag, Sr, Ge, Zn,
Sn, Cd, Sb, Tl, and Hg. Of these, Bi, In, Pb, Zn, Sn, Sb, and Tl
are preferred, and Sn is more preferred.
[0128] As specific preferable examples of the salt of the metal
(a'), there can be mentioned chlorides, sulfates and nitrates of a
metal selected from a group consisting of Bi, In, Pb, Si, Ag, Sr,
Ge, Zn, Sn, Cd, Sb, Tl, and Hg as the metal (a'), which are readily
dissolved in the solvent (d) to form metal ions. Of these,
chlorides, sulfates and nitrates of a metal selected from a group
consisting Bi, In, Pb, Zn, Sn, Sb, and Tl are preferred, because
these salts are readily dissolved in the solvent (d) to stably form
metal ions. Particularly, chlorides, sulfates and nitrates of Sn
are more preferred, because these salts of Sn make it possible to
form an alloy with a transition metal while readily forming
amorphous portion (amorphous phase).
[0129] Specific preferable examples of the metal complex of the
metal (a') are amine complexes, fluoro complexes, polyamine
complexes, and polyphrin complexes of a metal selected from a group
consisting of Bi, In, Pb, Si, Ag, Sr, Ge, Zn, Sn, Cd, Sb, Tl, and
Hg as the metal (a'), which are readily dissolved in the solvent
(d) to form metal ions.
[0130] The above-mentioned metal salts and metal complexes may be
used either singly or in combination of two or more of them.
[0131] Besides, organometallic compounds, e.g., alkyl compounds,
phenyl compounds, and the like, of a metal selected from a group
consisting of Bi, In, Pb, Si, Ag, Sr, Ge, Zn, Sn, Cd, Sb, Tl, and
Hg which are soluble in the solvent (d) are also usable as the
metal compound (a).
[0132] Transition Metal Compound (b):
[0133] The transition metal compound (b) includes transition metal
salts and transition metal complexes of the transition metal (b').
These transition metal salts and transition metal complexes are
soluble in the solvent (d).
[0134] The transition metal (b') can include Cr, Mn, Fe, Co, Ni,
Cu, Mo, Tc, Ru, Rh, Pd. Ag, Os, Ir, Pt, Au, Ti, V, Y, Sc, Zr, Nb,
Hf, Ta, and W. Of these, Cr, Mn, Fe, Co, Ni, Cu, Ru, Rh, Pd, Ag,
Os, Ir, Pt, and Au are preferred, and Cr, Mn, Fe, Co, Ni, and Cu
are more preferred.
[0135] As specific preferable examples of the transition metal salt
of the transition metal (b'), there can be mentioned chlorides,
sulfates and nitrates of a transition metal selected from a group
consisting of Cr. Mn, Fe, Co, Ni, Cu, Mo, Tc, Ru, Rh, Pd, Ag, Os,
Ir, Pt, Au, Ti, V, Y, Sc, Zr, Nb, Hf, Ta, and W as the transition
metal (b'), which are readily dissolved in the solvent (d) to form
metal ions. Of these, chlorides, sulfates and nitrates of a
transition metal selected from a group consisting Cr, Mn, Fe, Co,
Ni, Cu, Ru, Rh, Pd, Ag, Os, Ir, Pt, and Au are preferred, because
these salts are readily dissolved in the solvent (d) to stably form
metal ions. Particularly, chlorides, sulfates and nitrates of a
transition metal selected from a group consisting of Cr, Mn, Fe,
Co, Ni, and Cu are more preferred, because these salts make it
possible to form an alloy with a metal capable of being alloyed
with lithium while readily forming amorphous portion (amorphous
phase).
[0136] Specific preferable examples of the metal complex of the
metal (b') are amine complexes, fluoro complexes, polyamine
complexes, and polyphrin complexes of a metal selected from a group
consisting of Cr, Mn, Fe, Co, Ni, Cu, Mo, Tc, Ru, Rh, Pd, Ag, Os,
Ir, Pt, Au, Ti, V, Y, Sc, Zr, Nb, Hf, Ta, and W as the transition
metal (b'), which are readily dissolved in the solvent (d) to form
metal ions.
[0137] The above-mentioned transition metal salts and transition
metal complexes may be used either singly.or in combination of two
or more of them.
[0138] Besides, organometallic compounds, e.g., alkyl compounds,
phenyl compounds, and the like, of a transition metal selected from
a group consisting of Cr, Mn, Fe, Co, Ni, Cu, Mo, Tc, Ru, Rh, Pd,
Ag, Os, Ir, Pt, Au, Ti, V, Y, Sc, Zr, Nb, Hf, Ta, and W which are
soluble in the solvent (d) are also usable as the transition metal
compound (b).
[0139] Complexing Agent (c):
[0140] As the complexing-agent (c), there can be used an adequate
compound which makes it possible to form a complex with the
foregoing metal ion [that is, the ion of the metal (a') and the ion
of the transition metal (b')] in the solvent (d). However, as the
complexing agent (c), it is preferred to use a prescribed compound
which makes the foregoing mixed solution to contain a complex which
is formed by the metal (a') and said compound as the complexing
agent (c) and also a complex which is formed by the transition
metal (b') and said compound as the complexing agent (c). By adding
such compound as the complexing agent (c), it is possible that the
foregoing metal ion forms a desiredcomplexsothatitcanpresentasst-
able ion in the solvent even when the temperature, the pH value or
the like of the mixed solution is changed during the reaction
operation. Further, the reduction reaction is efficiently occurred,
and as a result, the generation of impurity is diminished and the
yield of a product is improved.
[0141] The formation of such complex formed by the metal ion and
the complexing agent can be confirmed by means of spectrochemical
analysis in ultraviolet and visible region or infrared spectrum
analysis in which analysis is performed based on a spectral
position or a spectral shift.
[0142] As specific preferable examples of the complexing agent (c),
there can be mentioned cyanides; thiocyanic acid and salts thereof;
nitrous acid and salts thereof; ammonia and salts thereof; amines
such as pyridine, bipyridine, ethylenediamine, and
dietylenetriamine and slats thereof; ketones such as acetylacetone;
organic carboxylic acids such as urea, oxalic acid, citric acid,
tartaric acid, and ethylenediaminetetraacetic acid and salts
thereof; amino acids such as arginine and alanine; and polyols such
as ethylene glycol and polyethylene glycol. Of these, amines and
organic carboxylic acids, particularly citric acid and
ethylenediaminetetraacetic acid and salts thereof are preferred
because they make it possible to stably form a desired complex
during the reaction, where a homogeneous alloy can be formed.
[0143] The above-mentioned compounds as the complexing agent (c)
may be used either singly or in combination two or more of
them.
[0144] Solvent (d):
[0145] As the solvent (d), there can be used any solvents as long
as the metal compound (a), the transition metal compound (b), the
complex of the metal compound (a) and the complexing agent (c), and
the complex of the transition metal compound (b) and the complexing
agent (c) are uniformly dispersed and dissolved therein so that a
homogeneous alloy material can be formed.
[0146] Such solvent can include water and polar solvents. Specific
examples of the polar solvent are alcohols such as methanol,
ethanol, and ethylene glycol; esters such as ethyl acetate, butyl
acetate, ethylene carbonate, propylene carbonate, and dimethyl
carbonate; amides such as formamido, N,N-dimethylformamide,
N,N-dimethylacetamide, 1,3-dimethyl-2-imidazolidinone, and
N-methylpyrrolidone; nitrites such as acetonitrile, propionitrile,
succinonitrile, and benzonitrile; amines such as ethylenediamine,
triethyleneamine, aniline, pyridine, and piperidine; halogen
compounds such as methylene chloride, chloroform,
1,2-dichloroethane, chlorobenzene, and 1-bromo-2-chloroethane;
sulfur compounds such as dimethyl sulfoxide, and sulfolane; liquid
ammonium; and glacial acetic acid. Of these, water and alcohols are
preferred because the solubility of the complex of the metal
compound (a) and the complexing agent (c) and that of the complex
of the transition metal compound (b) and the complexing agent (c)
are high therein.
[0147] The above-mentioned solvents may be used either singly or in
combination of two or more of them.
[0148] Reducing Agent (e):
[0149] The reducing agent (e) comprises a compound which can reduce
the foregoing ion [that is, the ion of the metal (a') and the ion
of the transition metal (b')] and which has an electrode potential
(which is provided by the ion or element contained in said compound
as the reducing agent), which is inferior to the electrode
potential (E) of each of the metal (a') and the transition metal
(b'). That is, as the reducing agent (e), there is used such a
compound that when said compound as the reducing agent exists
together with the ion of the metal (a') and the ion of the
transition metal (b'), these metal ions are likely to be reduced
and the compound is likely to be oxidized.
[0150] The electrode potential (E) is meant an electric potential
between a normal hydrogen electrode and a given metal when a
combination of said normal hydrogen electrode and said metal is
immersed in a solution containing ion of said metal. In general,
the dissociation degree of the ion is changed depending upon the
temperature or the pH value of the solution, and because of this,
the electrode potential is also changed.
[0151] Particularly, as the reducing agent (e), there is used an
adequate compound whose electrode potential in the liquid state
upon the reduction reaction is inferior to the the electrode
potential of the metal (a') or that of the transition metal (b')
which is the lowest. Particularly, the electrode potential of the
compound as the reducing agent is preferred to be inferior by more
than 0.1 V or preferably more than 0.2 V to that of metal (a') or
the transition metal (b') which is the lowest, because the
reduction reaction is efficiently occurred in this case.
[0152] As previously described, the electrode potential of the
reducing agent is changed depending upon the temperature or the pH
value of the mixed solution. Therefore, it is inconvenient to
select an adequate compound suitable as the reducing agent (e).
However, by referring to a normal electrode potential (E.degree.)
as a guide, it is possible to select such compound having a normal
electrode potential which is lower than the electrode potential of
each of the metal compound (a) and the transition metal compound
(b).
[0153] The normal electrode potential (E.degree.) here can be
obtained from the electrode potential (E) in accordance with the
equation E.degree.=E-(RT/nF)1na, with R being a gas constant, T
being an absolute temperature, F being a Faraday constant, n being
an ion valency, and a being an activity of a metal ion in a
solution.
[0154] That is, the normal electrode potential (E.degree.) is an
electrode potential when a=1, and it is indicated by an electrode
potential which is exhibited when the concentration of a solute
constituting a monopole in the solution is in a standard state
(a=1) which is 1 atmospheric pressure in the case of a gas and
which is in the most stable state (with respect to the pH value or
temperature) in the case of a solid or liquid. The electrode
potential has an inherent value depending upon the kind of a
material involved.
[0155] In the case where at least one kind of a metal compound
selected from a group consisting of hydrochlorides of Sn, sulfates
of Sn and nitrates of Sn is used as the metal compound (a), when a
given compound is such that the an aqueous solution thereof
maintained at an aqueous solution maintained at 25.degree. C. has a
normal electrode potential which is lower than the electrode
potential of said metal compound, said compound can be used as the
reducing agent (e). However, it is preferred to use a reducing
agent comprising a compound whose normal electrode potential is
less than -0.2 V or preferably less than -0.5 V, because the
reduction of Sn is efficiently occurred in this case.
[0156] And said compound as the reducing agent is soluble in the
solvent (d), the compound is preferable because the reduction
reaction is uniformly occurred. Further, when the compound is still
soluble in the solvent even after it is oxidized, the compound is
more preferable because contamination of impurity into an alloy
particulate deposited by the reaction is diminished.
[0157] Such compound which can satisfy these conditions as the
reducing agent (e) can include lower oxygen compounds such as
hypophosphorous acid, phosphorous acid, sulfurous acid,
thiosulfuric acid, and dithionous acid and salts of these
compounds; metal salts in the low valence state of Fe (II), Ti
(III) and Cr (II); organic compounds such as formaldehyde, formic
acid, and oxalic acid and salts of these organic compounds. In the
present invention, these compounds can be used either singly or in
combination of two or more of them as the reducing agent (e).
[0158] In the following, description will be made of an electrode
material produced by the electrode material-producing process of
the present invention.
[0159] As previously described, the electrode material produced
according to the present invention comprises an amorphous alloy
material (including an amorphous alloy particulate) chiefly
comprising at least one kind of a metal (a') capable of being
alloyed with lithium and at least one kind of a transition metal
(b').
[0160] The metal (a') can include Bi, In, Pb, Si, Ag, Sr, Ge, Zn,
Sn, Cd, Sb, Tl, and Hg. Of these, Bi, In, Pb, Zn, Sn, Sb, and Tl
are preferred, and Sn is more preferred. The metal (a') may
comprise one or more of these metals.
[0161] The transition metal (b') can include Cr. Mn, Fe, Co, Ni,
Cu, Mo, Tc, Ru, Rh, Pd, Ag, Os, Ir, Pt, Au, Ti, V, Y, Sc, Zr, Nb,
Hf, Ta, and W. Of these, Cr, Mn, Fe, Co, Ni, Cu, Ru, Rh, Pd, Ag,
Os, Ir, Pt, and Au are preferred, and Cr, Mn, Fe, Co, Ni, and Cu
are more preferred. The transition metal (b') may comprise one or
more of these transition metals.
[0162] The electrode material produced according to the present
invention also includes an amorphous alloy material (including an
amorphous alloy particulate) chiefly comprising at least one kind
of a metal (a') selected from a group consisting of the
above-mentioned metals capable of being alloyed with lithium and at
least one kind of a transition metal (b') selected from a group
consisting of the above-mentioned transition metals and which
contains at least one kind of an element selected from a group
consisting of B, C, N, O, P, and S. This amorphous alloy material
may be produced by making a compound containing at least one kind
of an element selected from a group consisting of B, C, N, O, P,
and S to exist together with the foregoing metal compound (a) and
the foregoing transition metal compound (b) in the reaction system.
These elements have an atomic radius which is smaller than that of
each of the metal (a') and the transition metal (b'), and because
of this, they facilitate the amorphization. Particularly, B, C, N,
and P has a more small atomic radius and therefore, these elements
are more preferred for the amorphization.
[0163] In a preferred embodiment, the electrode material produced
according to the electrode material-producing process of the
present invention comprises an amorphous alloy material (including
an amorphous alloy particulate) containing a Sn.A.X alloy with a
substantially non-stoichiometric ratio composition as a principal
constituent. For the formula Sn.A.X, A indicates at least one kind
of a transition metal element selected from a group consisting of
Cr, Mn, Fe, Co, Ni, Cu, Mo, Tc, Ru, Rh, Pd, Ag, Os, Ir, Pt, Au, Ti,
V, Y, Sc, Zr, Nb, Hf, Ta, and W, X indicates at least one kind of
an element selected from a group consisting of B, C, N, O and S,
where the element X is not always necessary to be contained. The
content of the constituent element Sn of the amorphous Sn.A.X alloy
is preferred to have a relationship of Sn/(Sn+A+X)=20 to 80 atomic
% in terms of the number of atoms of each element (atom) of the
entire constituent elements Sn, A and X.
[0164] The "amorphous alloy with a substantially non-stoichiometric
ratio composition" in the present invention means an amorphous
alloy in which more than two kinds of metal elements are not bonded
at a simple integral ratio. That is, the "amorphous alloy with a
substantially non-stoichiometric ratio composition" in the present
invention is distinguished from an intermetallic compound in which
more than two kinds of metal elements are bonded at a simple
integral ratio. More concretely, the element composition of the
"amorphous alloy" in the present invention is distinguished from
that of any of known intermetallic compounds (which have a regular
atomic arrangement and a crystalline structure which is quite
different from that of each constituent metal), namely, it is
distinguished from the composition (the stoichiometric composition)
expressed by a prescribed structural formula in which more than two
kinds of metal elements are bonded at a simple integral ratio. It
should be noted to the fact that those compounds in which more than
two kinds of metal elements are bonded at a simple integral ratio
and which have a regular atomic arrangement and a crystalline
structure which is quite different from that of each constituent
metal are known as intermetallic compounds.
[0165] The "amorphous alloy with a substantially non-stoichiometric
ratio composition" in the present invention is distinguished from
such intermetallic compound.
[0166] For instance, as for Sn--Co alloy, it is widely known that
Sn.sub.2Co.sub.3, SnCo, and Sn.sub.2Co which have a composition
ratio in which the atomic ratio of Sn and Co is a simple integral
ratio are intermetallic compounds.
[0167] However, the composition ratio of a Sn--Co alloy with the
non-stoichiometric ratio composition which is produced by the
electrode material-producing process of the present invention (see,
example which will be later described) is deviated from that of
said intermetallic compound and therefore, the former is clearly
distinguished from the latter. In this way, the "amorphous alloy"
in the present invention is of the composition which is quite
different from the stoichiometric composition. In view of this, the
"amorphous alloy" in the present invention is identified by the
term "amorphous allow with a non-stoichiometric ratio
composition".
[0168] Whether or not the amorphous alloy particulate contains
amorphous phase or whether or not it is truly amorphous may be
confirmed by the following analytical method.
[0169] In a X-ray diffraction chart of a given specimen in which a
peak intensity against a diffraction angle by X-ray diffraction
analysis using K.alpha.-rays of Cu is appeared, in the case where
the specimen is crystalline, a sharp peak is appeared. However, in
the case where the specimen contains amorphous phase, a broad peak
with a widened half width is appeared, and in the case where the
specimen is completely amorphous, no X-ray diffraction peak is
appeared. Separately, according to a radial distribution function
curve which is obtained by way of calculation on the basis of data
obtained in the X-ray diffraction analysis of a specimen, said
radial distribution function curve being of a function showing the
situation that for a given atom, existential probability of other
atom is present at a point being apart from said given atom at a
given distance, in the case where the specimen is amorphous, being
different from the case of a crystalline whose interatomic distance
is constant wherein a sharp peak is appeared at every point of a
definite distance, it is understood that the density at a short
distance in the vicinity of the foregoing given atom is large but
it is diminished as the distance from the atom becomes distant.
[0170] According to an electron diffraction pattern obtained by
electron diffraction analysis, it is understood that in the course
of shifting from a spot pattern of a crystalline to an amorphous
nature, there are observed electron diffraction pattern changes
from a ring pattern to a diffuse ring pattern, then to a halo
pattern. In the case where a material has a diffuse ring pattern,
it is understood that the material contains amorphous phase. In the
case where a material has a halo pattern, it is understood that the
material is amorphous.
[0171] According to analysis by means of a differential scanning
calorimeter (DSC), for an amorphous phase-bearing metal powder,
there is observed a calorific peak due to crystallization upon
heating said metal powder (in the case of an amorphous
phase-bearing Sn alloy powder, when it is heated at a temperature
in a range of from 200.degree. C. to 600.degree. C.).
[0172] Now, in the case where an amorphous alloy particulate has an
increased amorphous phase proportion, it is understood from a peak
appeared in a X-ray diffraction chart where a sharp peak is
appeared in the case of a crystalline, but a broad peak with a
widened half width is appeared in the above case.
[0173] The amorphous alloy material (particulate) produced by the
production process of the present invention has a peak appeared in
a range of 2.theta.=20.degree. to 50.degree. in X-ray diffraction
with K.alpha.-rays of Cu, having a half width of preferably more
than 0.2.degree., more preferably more than 0.5.degree..
[0174] The amorphous alloy material (particulate) has a crystallite
size, which is calculated based on data obtained in the X-ray
diffraction analysis of said amorphous alloy material (in an unused
state) before neither charging nor discharging is operated for said
amorphous alloy material, which is preferably in a range of less
than 50 nm, more preferably in a range of less than 20 nm.
[0175] The crystallite size of the amorphous alloy material
(particulate) can be determined from the half width and diffraction
angle of a peak of a X-ray diffraction curve obtained using a
radiation source comprising K.alpha.-rays of Cu and in accordance
with the following Scherrer's equation.
Lc=0.94.lambda./(.beta. cos .theta.) (Scherrer's equation)
[0176] Lc: crystallite size
[0177] .lambda.: wavelength of X-ray beam
[0178] .beta.: half width (radian) of the peak
[0179] .theta.: Bragg angle of the diffraction line
[0180] The proportion of the amorphous phase in the amorphous alloy
material (particulate) can be readily obtain by making a X-ray
diffraction peak intensity obtained from a crystallized product,
which is obtained by subjecting a sample of said amorphous alloy
material to a heat treatment at a temperature of more than
600.degree. C. in an atmosphere composed of inert gas or hydrogen
gas, to be a crystalline of 100% (intensity Ic).
[0181] When the X-ray diffraction peak intensity of the amorphous
alloy material is made to be Ia, the proportion of the amorphous
phase is: (1-Ia/Ic).times.100%.
[0182] As specific examples of the amorphous Sn.A.X alloy material
produced by the production process of the present invention, there
can be mentioned those as will be illustrated below.
[0183] (1) Specific examples of the amorphous alloy material with a
composition comprising Sn element and the foregoing element A which
comprises at least one kind of a transition metal element selected
from a group consisting of Co, Ni, Fe, Cu, Cr, and Mn are: Sn--Co
amorphous alloy, Sn--Ni amorphous alloy, Sn--Fe amorphous alloy,
Sn--Cu amorphous alloy, Sn--Co--Ni amorphous alloy, Sn--Co--Cu
amorphous alloy, Sn--Co--Fe amorphous alloy, Sn--Ni--Cu amorphous
alloy, Sn--Ni--Fe amorphous alloy, Sn--Co--Fe--Ni--Cr amorphous
alloy, Sn--Co--Fe--Ni--Cr--Mn amorphous alloy,
Sn--Co--Cu--Fe--Ni--Cr amorphous alloy, and
Sn--Co--Cu--Fe--Ni--Cr--Mn amorphous alloy.
[0184] (2) Specific preferable examples of the amorphous alloy
comprising any of the compositions described in the above (1) to
which the foregoing element X which comprises at least one kind of
an element selected from a group consisting of B, C, N, O, P, and S
is added are: Sn--Co--C amorphous alloy, Sn--Ni--C amorphous alloy,
Sn--Fe--C amorphous alloy, Sn--Cu--C amorphous alloy,
Sn--Fe--Ni--Cr--C amorphous alloy, Sn--Co--Fe--Ni--Cr--C amorphous
alloy, Sn--Cu--Fe--Ni--Cr--C amorphous alloy,
Sn--Co--Fe--Ni--Cr--Mn--C amorphous alloy, Sn--Co--Cu--Fe--Ni--Cr--
-Mn--C amorphous alloy, Sn--Co--P amorphous alloy, Sn--Ni--P
amorphous alloy, Sn--Fe--P amorphous alloy, Sn--Cu--P amorphous
alloy, Sn--Co--B amorphous alloy, Sn--Ni--B amorphous alloy,
Sn--Fe--B amorphous alloy, Sn--Cu--B amorphous alloy, Sn--Co--P
amorphous alloy, Sn--Co--N amorphous alloy, Sn--Ni--N amorphous
alloy, Sn--Fe--N amorphous alloy, Sn--Cu--N amorphous alloy,
Sn--Co--S amorphous alloy, Sn--Ni--S amorphous alloy, Sn--Fe--S
amorphous alloy, and Sn--Cu--S amorphous alloy.
[0185] In a preferred embodiment, the electrode material produced
by the electrode material-producing process of the present
invention comprises an amorphous alloy particulate having an
average particle size preferably in a range of from 0.1 .mu.m to 2
.mu.m or more preferably in a range of from 0.1 .mu.m to 1 .mu.m.
Said amorphous alloy particulate is desired to have a particle size
distribution preferably in a range of from 0.01 .mu.m to 20 .mu.m,
more preferably in a range of from 0.05 .mu.m to 5 .mu.m, or most
preferably in a range of from 0.05 .mu.m to 1 .mu.m.
[0186] The average particle size and the particle size distribution
can be determined by a measuring method using a laser scattering
method or a measuring method by means of a scanning electron
microscope.
[0187] Further, said amorphous alloy particulate is desired to have
a specific surface area preferably in a range of more than 10
m.sup.2/g or more preferably in a range of more than 30 m.sup.2/g.
The specific surface area can be measured by means of a BET
(Brunauer-Emmett-Teller) method using gas absorption.
[0188] In addition, aforesaid amorphous alloy particulate is
desired to comprises particles preferably in a spherical form or
more preferably in a form similar to a round form. Particularly,
said amorphous alloy particulate is preferred to have a sphericity
in that a value of [longest length of particle]/[shortest length of
particle] is preferably in a range of 1.0 to 2.0 or more preferably
in a range of 1.0 to 1.5 in an average value.
[0189] The "longest length of particle" and the "shortest length of
particle" are meant that for an apparent plane of one particle of
the amorphous alloy particulate in the observation by a scanning
electron microscope, a length in a line direction which crosses the
center of the plane and which becomes the longest is expressed as
"longest length of particle", and a length in a line direction
which crosses the center of the plane and which becomes the
shortest is expressed as "shortest length of particle". And a value
of [longest length of particle]/[shortest length of particle] for
said one particle is a value of said "longest length of particle"
to said "shortest length of particle".
[0190] An average value of [longest length of particle]/[shortest
length of particle] for the amorphous alloy particulate can be
determined by obtaining a value of [longest length of
particle]/[shortest length of particle] for each of, for instance,
20 particles of the amorphous alloy particulate in the manner as
described in the above and calculating an average value of the
resultant 20 values of [longest length of particle]/[shortest
length of particle].
[0191] Now, in the step of forming an amorphous alloy by way of the
chemical reduction reaction in the electrode material-producing
process of the present invention, the reduction reaction is
performed in the solvent and therefore, the reduction reaction is
uniformly occurred in the entire reaction system as previously
described. Because of this, there is an effect in that there is
afforded an amorphous alloy particulate comprising particles having
a relatively uniform particle form and a relatively uniform
particle size. This effect is more improved by conducting agitation
upon the reduction reaction treatment such that said amorphous
alloy particulate afforded becomes to comprise particles having a
desirably complete particle size and a desirably complete particle
form similar to a round form.
[0192] In the following, description will be made of an electrode
structural body and a process for producing said electrode
structural body in the present invention.
[0193] FIG. 4 is a schematic cross-sectional view illustrating an
electrode structural body 405 which contains an electrode material
comprising an amorphous alloy material (particulate) obtained by
the electrode material-producing process of the present
invention.
[0194] The electrode structural body 405 shown in FIG. 4 comprises
an electrode material layer 404 (an electrode active material
layer) provided on a collector 400. The electrode material layer
404 comprises an amorphous alloy particulate 401, a binder 402, and
an electrically conductive auxiliary 403. In FIG. 4, the electrode
material layer 404 is provided only on one side of the collector
400. However, it is possible for the electrode material layer to be
provided on each of the opposite faces of the collector 400.
[0195] Description will be made of examples of a process for
producing the electrode structural body 405.
[0196] The electrode structural body 405 shown in FIG. 4 may be
prepared by mixing a given amorphous alloy particulate 401 of
obtained by the electrode material-producing process of the present
invention which is capable of being alloyed with lithium in the
electrochemical reaction, a given electrically conductive auxiliary
403, and a given binder 402 to obtain a mixture, adding a given
solvent to said mixture while adjusting the viscosity to obtain a
paste, applying said paste on a collector 400, and drying the paste
applied to form an electrode material layer 404 on the collector
400. In this case, the thickness or density of the electrode
material layer 404 formed may be adjusted by means of roll press or
the like.
[0197] The application of the above paste on the collector may be
conducted, for instance, by a coater coating method or a
screen-printing method.
[0198] The electrode material layer 404 may be formed by arranging
a mixture obtained by mixing the amorphous alloy particulate, the
electrically conductive auxiliary and the binder without using the
solvent or a mixture obtained by mixing the amorphous alloy
particulate and the electrically conductive auxiliary without using
the solvent and the binder on the collector and subjecting the
mixture arranged on the collector to a press forming treatment.
[0199] In the following, description will be made of the collector
400, the binder 402, and the electrically conductive auxiliary
403.
[0200] Collector 400:
[0201] The collector 400 serves to supply an electric current such
that said electric current can be efficiently consumed for the
electrode reaction upon charging and it also serves to collect an
electric current generated upon discharging. Particularly in the
case where the electrode structural body 404 is used as the anode
of a rechargeable lithium battery, as the constituent of the
collector 400, it is desired to use a material having a high
electric conductivity and which is inactive to the battery
reaction. As preferable examples of such material, there can be
mentioned metallic materials which are incapable of being alloyed
with lithium in the electrochemical reaction. Specific examples of
such metallic material are metals such as Cu, Ni, Fe, Ti, and the
like, and alloys of these metals such as stainless steel. The
collector 400 is desired to be in the form of a plate shape. The
plate shape in this case may be of a thickness in a practical
range. The plate shape can include a so-called "foil" configuration
with a thickness of about 100 .mu.m or less. Besides, it is
possible to employ a mesh member, a sponge member, a fibrous
member, a punching metal member, and an expanded metal member,
respectively in the form of a plate shape.
[0202] Binder 402:
[0203] As the binder 402, it is possible to use an organic polymer
material which is water-soluble or water-insoluble. However, it is
more preferred to use a water-soluble organic polymer material as
the binder 402.
[0204] Specific examples of such water-soluble organic polymer
material are polyvinyl alcohol, carboxymethyl cellulose, methyl
cellulose, ethyl cellulose, isopropyl cellulose, hydroxymethyl
cellulose, hydroxyethyl cellulose, hydroxypropylmethyl cellulose,
cyanoethyl cellulose, ethyl-hydroxyethyl cellulose, starch,
dextran, pullulan, polysarcosine, polyoxyethlene,
polyN-vinylpyrrolidone, gum arabic, tragacanth gum, and polyvinyl
acetate.
[0205] Specific examples of such water-insoluble organic polymer
material are fluorine-containing polymers such as polyvinyl
fluoride, polyvinylidene fluoride, tetrafluoroethylene polymer,
trifluoroethylene polymer, difluoroethylene polymer,
ethylene-tetrafluoroethylene copolymer,
tetrafluoroethylene-hexafluoropropylene copolymer,
tetrafluoroethylene-perfluoroalkylvinyl ether copolymer, and
trifluoroetylene chloride polymer; polyolefins such as polyethylene
and polypropylene; ethylene-propylene-diethane terpolymer; silicone
resin; polyvinyl chloride; and polyvinyl butyral.
[0206] The rate occupied by the binder 402 in the electrode
material layer 404 is desired to be preferably in a range of from
1% by weight to 20% by weight or more preferably in a range of from
2% by weight to 10% by weight in order to retain a large amount of
an active material in the electrode material layer upon
charging.
[0207] Electrically Conductive Auxiliary 403:
[0208] The electrically conductive auxiliary 403 can include
amorphous carbon materials such as acetylene black, ketjen black,
and the like, carbonous materials such as graphite structure
carbon, and the like, and metallic materials such as Ni, Cu, Ag,
Ti, Pt, Al, Co, Fe, Cr, and the like. As the electrically
conductive auxiliary, for example, such carbon material or such
metallic material as above illustrated is used by blending it in an
amount in a range of from 0 to 30% by weight of the electrode
material layer.
[0209] The electrically conductive auxiliary 403 is preferred to be
in a spherical form, a flake form, a filament form, a fabric form,
a spike form, or a needle form. In a more preferred embodiment, by
adopting two kinds of forms of these forms, it is possible to
increase the packing density upon forming the electrode material
layer so that the resulting electrode material layer has a small
impedance.
[0210] Now, an electrode material comprising an amorphous alloy
material (particulate) obtained by the electrode material-producing
process of the present invention which is used in the electrode
material layer (the active material layer) has a volume expansion
upon charging in comparison with a conventional carbonous material
such as graphite or the like. Because of this, when the density of
the electrode material layer formed on the collector using the
amorphous alloy material (particulate) as its principal constituent
material is excessively high, there is a tendency that the volume
of the electrode material layer is expanded upon charging and
peeling is liable to occur between the electrode material layer and
the collector. In the case where the density of the electrode
material layer is excessively small, there is a tendency that the
contact resistance among the particles of the amorphous alloy
particulate is liable to increase whereby reducing the
current-collecting performance. In this connection, the density of
the electrode material layer is desired to be preferably in a range
of from 2.3 to 3.5 g/cm.sup.3 or more preferably in a range of from
2.3 to 3.0 g/cm.sup.3.
[0211] In the following, description will be made of an example of
a rechargeable lithium battery and a process for producing said
rechargeable lithium battery in the present invention.
[0212] FIG. 5 is a conceptual view schematically illustrating the
constitution of a rechargeable lithium battery according to the
present invention. As shown in FIG. 5, an anode 501 comprising the
foregoing electrode structural body (405) of the present invention
and a cathode 502 are accommodated in a battery housing 507 (a
battery case) such that they are opposed to each other through an
ion conductor 504 (an electrolyte). And an anode terminal 505 is
electrically connected to the anode 501, and a cathode terminal 506
is electrically connected to the cathode 502. Reference numeral 503
indicates an electrolyte solution comprising an electrolyte
dissolved in a solvent.
[0213] In the present invention, by using an electrode structural
body (405) having such configuration as shown in FIG. 4 as the
anode 501, because the anode 501 comprises a specific amorphous
alloy material (particulate) which is expanded a little when it is
alloyed with lithium upon charging, expansion and shrinkage of the
anode are quite small in the battery housing 507 even when the
charging and discharging cycle is repeated, where the electrode
material layer (which retains lithium upon charging) of the anode
scarcely suffers fatigue failure. Thus, the rechargeable lithium
battery has a markedly prolonged charging and discharging cycle
life.
[0214] Description will be made of each constituent of the
rechargeable lithium battery.
[0215] Anode 501:
[0216] As the anode 501, the foregoing electrode structural bodies
(405) of the present invention can be used as it is.
[0217] Cathode 502:
[0218] The cathode 502 as a counter electrode to the anode
comprising aforesaid electrode structural body in the rechargeable
lithium battery comprises at least a cathode active material
capable of being a host material for lithium ion and a collector.
Preferably, the cathode comprises a layer formed of said cathode
active material capable of being a host material for lithium ion
and a collector. The layer formed of the cathode material is
preferred to comprise said cathode active material capable of being
a host material for lithium ion and a binder, if necessary, also an
electrically conductive auxiliary.
[0219] As the cathode active material capable of being a host
material for lithium ion used in the rechargeable lithium battery,
transition metal oxides, transition metal sulfides, transition
metal nitrides, lithium-transition metal oxides, lithium-transition
metal sulfides, and lithium-transition metal nitrides may be
selectively used. The transition metal elements of these transition
metal oxides, transition metal sulfides, and transition metal
nitrides can include metal elements having a d-shell or f-shell.
Specific examples of such metal element are Sc, Y, lanthanoids,
actinoids, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Tc, Re, Fe, Ru,
Os, Co, Rh, Ir, Ni, Pb, Pt, Cu, Ag, and Au.
[0220] It is preferred also for the cathode active material (or the
cathode material) to comprise an amorphous phase-bearing material
in order to increase the amount (that is, the storage capacity) of
lithium ion which intercalates. As well as in the case of the
amorphous alloy material (particulate) constituting the anode, the
amorphous phase-bearing material is desired to be such that in a
X-ray diffraction chart (of X-ray diffraction intensity against a
diffraction angle of 2.theta.), has a main peak with a half width
preferably of more than 0.2.degree. or more preferably of more than
0.5.degree. respectively against 2.theta..
[0221] In the case where the cathode active material is in a
powdery form, a cathode active material layer is formed by mixing
said powder cathode active material with a binder to obtain a
mixture and applying said mixture on the collector or by sintering
said powder cathode active material on the collector, whereby
forming the cathode. In the case where the conductivity of the
powdery cathode active material is insufficient, as well as in the
case of forming the electrode material layer (as the anode active
material layer) for the foregoing electrode structural body, an
adequate electrically conductive auxiliary is added. As said binder
and said electrically conductive auxiliary, those mentioned in the
above which are used for the formation of the electrode structural
body (405) of the present invention may be used.
[0222] The collector of the cathode may be constituted by a metal
such as Al, Ti, Pt, or Ni, or an alloy such as stainless steel.
[0223] Ion Conductor 504:
[0224] As the ion conductor 504 used in the rechargeable lithium
battery of the present invention, there may be used a separator
having an electrolyte solution (a supporting electrolyte solution
obtained by dissolving a given supporting electrolyte in an
adequate solvent) retained therein, a solid electrolyte, or a
solidified electrolyte obtained by gelling an adequate electrolyte
solution by a high molecular gelling agent.
[0225] The ion conductor used in the rechargeable lithium battery
of the present invention is necessary to have an ionic conductivity
at 25.degree. C. which is preferably more than 1.times.10.sup.-3
S/cm or more preferably more than 5.times.10.sup.-3 S/cm.
[0226] The supporting electrolyte can include inorganic acids such
as H.sub.2S0.sub.4, HCl and HNO.sub.3; salts of Li.sup.+ (lithium
ion) with Lewis acid ion such as BF.sub.4.sup.-, PF.sub.6.sup.-,
AsF.sub.6.sup.-, ClO.sub.4.sup.-, CF.sub.3SO.sub.3.sup.-, or
BPh.sub.4.sup.- (with Ph being a phenyl group); and mixtures of
these salts. Besides, salts of the above described Lewis acids ions
with cations such as sodium ion, potassium ion, tetraalkylammonium
ion, or the like are also usable.
[0227] In any case, it is desired that the above salts are used
after they are subjected to dehydration or deoxygenation, for
example, by way of heat treatment under reduced pressure.
[0228] The solvent in which the supporting electrolyte is dissolved
can include acetonitrile, benzonitrile, propylene carbonate,
ethylene carbonate, dimethyl carbonate, diethyl carbonate,
dimethylformamide, tetrahydrofuran, nitrobenzene, dichloroethane,
diethoxyethane, 1,2-dimethoxyethane, chlorobenzene,
.gamma.-butyrolactone, dioxolan, sulfolan, nitromethane, dimethyl
sulfide, dimethyl sufoxide, methyl formate,
3-methyl-2-oxdazolydinone, 2-methyltetrahydrofuran,
3-propylsydonone, sulfur dioxide, phosphoryl chloride, thionyl
chloride, sulfuly chloride, and mixtures of these.
[0229] As for these solvents, it is desired for them to be
subjected to dehydration using activated alumina, molecular sieve,
phosphorous pentaoxide, or calcium chloride, prior to their use.
Depending upon some of these solvents, it is desired for them to be
subjected to distillation in an atmosphere composed of inert gas in
the presence of an alkali metal, where moisture and foreign matter
are removed.
[0230] In order to prevent leakage of the electrolyte solution, it
is desired to use a solid electrolyte or solidified
electrolyte.
[0231] The solid electrolyte can include a glass material such as
an oxide material comprising lithium, silicon, phosphorus, and
oxygen elements, a polymer chelate comprising an organic polymer
having an ether structure, and the like.
[0232] The solidified electrolyte can include those obtained by
gelling a given electrolyte solution by a gelling agent to solidify
said electrolyte solution. As the gelling agent, it is desired to
use a polymer having a property of absorbing the solvent of the
electrolyte solution to swell or a porous material such as
silicagel, capable of absorbing a large amount of liquid. Said
polymer can include polyethylene oxide, polyvinyl alcohol,
polyacrylamide, polymethylmethacrylate, and polyacrylonitrile. And
these polymers are preferred to have a cross-linking structure.
[0233] The separator is disposed between the anode and the cathode,
and it serves to prevent the anode and the cathode from suffering
from internal-shorts. It also serves to retain an electrolyte
therein depending upon the situation. The separator having the
electrolyte retained therein functions as the ion conductor.
[0234] The separator is required to have a structure having a
number of perforations capable of allowing lithium ion to pass
therethrough and it is also required to be insoluble into and
stable to the electrolyte solution. The separator is preferred to
be constituted by a nonwoven fabric or a memberane having a
micropore structure, made of glass, a polyolefin such as
polypropylene, polyethylene or the like, or a fluororesin.
Alternatively, the separator may be constituted by a metal oxide
film or a resin film combined with a metal oxide, respectively
having a plurality of micropores. In a preferred embodiment, the
separator is constituted by a multilayered metal oxide film. In
this case, the separator effectively prevents a dendrite from
passing therethrough and because of this, occurrence of
internal-shorts between the anode and the cathode is desirably
prevented. Besides, the separator may be constituted by an
incombustible material such as a fluororesin film, a glass member
or a metal oxide film. In this case, the safety can be more
improved.
[0235] Shape and Structure of Rechargeable Battery:
[0236] The rechargeable battery of the present invention may be in
the form of a flat round shape, a cylindrical shape, a prismatic
shape, or a sheet-like shape. The structure of the rechargeable
battery of the present invention may take a single layer structure,
a spiral-wound cylindrical structure, or the like. In the case
where the rechargeable battery is of a spiral-wound cylindrical
structure, the anode, separator, and cathode are arranged in the
named order and they are spiral-wound and because of this, it has
advantages such that the battery area can be increased as desired
and a high electric current can be flown upon charging and
discharging. In the case where the rechargeable battery is of a
prismatic structure or a single layer structure, there is an
advantage in that the space of a device for housing the
rechargeable battery can be effectively utilized.
[0237] In the following, the shape and structure of a rechargeable
lithium battery of the present invention will be detailed with
reference to FIGS. 6 and 7.
[0238] FIG. 6 is a schematic cross-sectional view illustrating an
example of a single-layer flat round type (coin type) rechargeable
lithium battery according to the present invention. FIG. 7 is a
schematic cross-sectional view illustrating an example of a
spiral-wound cylindrical type rechargeable lithium battery
according to the present invention.
[0239] In FIGS. 6 and 7, each of reference numerals 601 and 703
indicates an anode, each of reference numerals 603 and 706 a
cathode, each of reference numerals 604 and 708 an anode terminal
(an anode cap or an anode can), each of reference numerals 605 and
709 a cathode terminal (a cathode can or a cathode cap), each of
reference numerals 602 and 707 an ion conductor, each of reference
numerals 606 and 710 a gasket, reference numeral 701 an anode
collector, reference numeral 704 a cathode collector, reference
numeral 711 an insulating plate, reference numeral 712 an anode
lead, reference numeral 713 a cathode lead, and reference numeral
714 a safety vent.
[0240] In the flat round type (coin type) rechargeable battery
shown in FIG. 6, the cathode 603 having a cathode material (active
material) layer and the anode 601 having an anode material (active
material) layer are stacked through the ion conductor 602
comprising a separator having at least an electrolyte solution
retained therein to form a stacked body, and this stacked body is
accommodated in the cathode can 605 as the cathode terminal from
the cathode side, where the anode side is covered by the anode cap
604 as the anode terminal. And the gasket 606 is disposed in the
remaining space of the cathode can.
[0241] In the spiral-wound cylindrical type rechargeable battery
shown in FIG. 7, the cathode 706 having a cathode material (active
material) layer 705 formed on the cathode collector 704 and the
anode 703 having an anode material (active material) layer 702
formed on the anode collector 701 are opposed to each other through
the ion conductor 707 comprising a separator having at least an
electrolyte solution retained therein, and wound in multiple to
form a stacked body having a multi-wound cylindrical structure. The
stacked body having the cylindrical structure is accommodated in
the anode can 708 as the anode terminal. The cathode cap 709 as the
cathode terminal is provided on the opening side of the anode can
708, and the gasket 710 is disposed in the remaining space of the
anode can. The electrode stacked body of the cylindrical structure
is isolated from the cathode cap side through the insulating plate
711. The cathode 706 is electrically connected to the cathode cap
709 through the cathode lead 713. The anode 703 is electrically
connected to the anode can 708 through the anode lead 712. The
safety vent 714 for adjusting the internal pressure of the battery
is provided on the cathode cap side.
[0242] In the above, each of the active material layer of the anode
601 and the active material layer 702 of the anode 703 comprises a
layer comprising an amorphous alloy material (particulate) obtained
by the electrode material-producing process of the present
invention.
[0243] In the following, description will be made of an example of
a process for fabricating a rechargeable lithium battery having
such configuration as shown in FIG. 6 or FIG. 7.
[0244] (1) A combination comprising the separator (602, 707)
interposed between the anode (601, 703) and the cathode (603, 706)
is positioned in the cathode can (605) or the anode can (708).
[0245] (2) The electrolyte is introduced thereinto, and the
resultant is assembled with the anode cap (604) or the cathode cap
(709) and the gasket (606, 710).
[0246] (3) The assembled body obtained in the step (2) is subjected
to a caulking treatment, whereby the rechargeable lithium battery
is completed.
[0247] In the battery fabrication, the preparation of the materials
for the rechargeable lithium battery and the assembly of the
battery are desired to be conducted in a dry air atmosphere whose
moisture having been sufficiently removed or in a dry inert gas
atmosphere.
[0248] Description will be made of the members used in the
fabrication of the above rechargeable lithium battery.
[0249] Insulating Packing:
[0250] The gasket (606, 710) may be constituted by a fluororesin, a
polyamide resin, a polysulfone resin, or a rubber material. The
sealing of the battery may be conducted by way of glass-sealing,
sealing using an adhesive, welding or soldering, besides the
caulking using the insulating packing shown in the case shown in
FIG. 6 or FIG. 7.
[0251] The insulating plate 711 shown in FIG. 7 may be constituted
by a material selected from organic resin materials and
ceramics.
[0252] Battery Housing:
[0253] The battery housing comprises the cathode can or the anode
can (605, 708), and the anode cap (604) or the cathode cap (709).
Such battery housing preferably comprises a stainless steel sheet.
Besides, it may comprise a titanium clad stainless steel sheet, a
copper clad stainless steel sheet or a nickel plating steel
sheet.
[0254] In the case of FIG. 6, the cathode can (605) also functions
as the battery housing, and in the case of FIG. 7, the anode can
(708) also functions as the battery housing, and therefore, the
battery housing in each case is desired to comprise a stainless
steel. However, in the case where neither the cathode can nor the
anode can also functions as the battery housing, a battery housing
comprising said stainless steel, a metallic material of iron or
zinc, a plastic material of polypropylene or the like, or a
composite material comprising a metallic material or a glass fiber
and a plastic material may be used.
[0255] Safety Vent:
[0256] In the rechargeable lithium battery, a safety vent may be
provided in order to ensure the safety when the internal pressure
in the battery is increased. The safety vent may comprise a rubber,
a spring, a metal ball or a rupture foil.
[0257] In the following, the present invention will be described in
more detail with reference to examples. However, the scope of the
present invention is not restricted to these examples. In the
following description, "part" and "%". stand for "part by weight"
and "% by weight" respectively.
EXAMPLE 1
[0258] In this example, there was prepared a rechargeable lithium
battery having such cross-sectional structure as shown in FIG. 6.
In the anode of the battery, there was used a Sn--Ni amorphous
alloy material (particulate) prepared by the electrode
material-producing process of the present invention. In the
cathode, there was used lithium cobaltate.
[0259] In the following, description will be made of preparation
procedures of respective constituents of the battery and
fabrication procedures of the battery with reference to FIG. 6,
starting from the preparation of an anode.
[0260] 1. Preparation of Anode 601:
[0261] (1). Preparation of an Alloy Powder (Particulate) as an
Electrode Material:
[0262] 5.3 parts of a pentahydrate of tin (IV) chloride as the
metal compound capable of being alloyed with lithium, 10.7 parts of
a hexahydrate of nickel (II) chloride as, the transition metal
compound, 75.0 parts of a dihydrate of trisodium citrate, 8.8 parts
of ethylene diamine tetra acetic acid, and 8.8 parts of a potassium
acetate respectively as the complexing agent were mixed with 100
parts of water as the solvent and sufficiently stirred to obtain a
mixed solution. The mixed solution was introduced into the reaction
vessel 201 (provided with the starting material introduction device
202, the reflux device 203, the gas introduction pipe 204, the
agitator 205, and the temperature controlling equipment 206) shown
in FIG. 2 through the starting material introduction device, and in
order to maintain the inside of the reaction vessel in a nitrogen
gas atmosphere, nitrogen gas was introduced into the reaction
vessel through the gas introduction pipe, where excessive nitrogen
gas was exhausted to the outside of the system through the reflux
device. The reaction vessel having the mixed solution therein was
heated to 70.degree. C. by means of the temperature controlling
equipment (water bath), and the mixed solution in the reaction
vessel was sufficiently stirred by means of the agitator.
[0263] Here, a specimen of the mixed solution treated in the above
was subjected to analysis by means of a visible-ultraviolet
absorption spectrum analyzer, where an identical peak was appeared
at a position of 600 nm and a peak shift from 390 nm to 380 nm was
observed. From this result, it was found that a complex formed by
the metal of the metal compound (capable of being alloyed with
lithium) and the complexing agent and a complex formed by the
transition metal of the transition metal compound and the
complexing agent are contained in the mixed solution.
[0264] Then, a solution obtained by dissolving 23.1 parts of a
titanium (III) chloride as the reducing agent in 73.3 parts of
water was heated to 70.degree. C. and added to the mixed solution
in the reaction vessel through the starting material introduction
device, followed by being sufficiently stirred. This adding and
mixing step was performed within one minute. The pH value of the
solution in the reaction vessel was measured. As a result, the
solution was found to have a pH value of 0.1.
[0265] Thereafter, a potassium hydroxide aqueous solution of 8N was
added to the solution in the reaction vessel through the starting
material introduction device while stirring the solution, so that
the pH value of the solution became to be 8.0, and the solution in
the reaction vessel was subjected to a heat treatment at 70.degree.
C. for 30 minutes. The adding and mixing step of the potassium
hydroxide aqueous solution here was performed within one
minute.
[0266] Thereafter, the content in the reaction vessel was taken out
from the vessel, and it was washed with water, and vacuum-dried at
50.degree. C. Thus, there was obtained a product comprising a
Sn--Ni alloy power.
[0267] A specimen of the resultant alloy powder was subjected to
analysis by means of X-ray microanalysis (XMA). As a result, only
Sn and Ni were detected without other elements being detected.
Then, the specimen was subjected to analysis by means of
inductively coupled plasma emission analysis (ICP). As a result,
the content of Sn and that of Ni were found to be 61% and 39%
respectively in terms of the atom number content.
[0268] Separately, using an X-ray diffraction device RINT 2000
(produced by Kabusiki Kaisha RIGAKU), a specimen of the resultant
alloy powder was subjected to wide angle X-ray diffraction analysis
using K.alpha.-rays of Cu as a radiation source, which gave peaks
having a widened half width appeared in a region of
2.theta.=25.degree. to 50.degree. as shown in FIG. 8(1). And there
were observed two main peaks one at 2.theta.=30.2.degree. and
another at 2.theta.=43.6.degree. in the X-ray diffraction chart,
having a half width of 0.80 and that of 0.6.degree., respectively.
The presence of these peaks having a wide half width indicates that
the resultant alloy powder is amorphous. Separately, calculation
was carried out on the basis of the half widths and the diffraction
angles of these peaks and in accordance with the foregoing
Scherrer's equation. As a result, there were obtained a crystallite
size of 11 nm and another crystallite size of 15 nm.
[0269] In addition, a specimen of the resultant alloy powder was
subjected to measurement of particle size distribution by means of
a particle size distribution measuring equipment using a laser
scattering method. As a result, it was found to have an average
particle size of 0.23 .mu.m and a particle size distribution of
0.06 to 0.9 .mu.m.
[0270] Further, a specimen of the resultant alloy powder was
examined by means of a scanning electron microscope. As a result,
it was found that an average value of the [longest length of
particle]/[shortest length of particle] is 1.3. From this result,
the resultant alloy powder was found to comprise spherical
particles.
[0271] Further in addition, a specimen of the resultant alloy
powder was subjected to measurement of specific surface area by
means of a BET method using nitrogen gas. As a result, it was found
to have a specific surface area of 80 m.sup.2/g.
[0272] (2). Preparation of an Electrode Structural Body as an Anode
601:
[0273] 90 parts of the Sn--Ni alloy powder obtained in the above, 5
parts of a graphite powder as an electrically conductive auxiliary,
2 parts of polyvinyl alcohol, and 3 parts of carboxymethyl
cellulose were mixed to obtain a mixture, and the mixture was mixed
with 100 parts of water as a solvent, and stirred to obtain a
paste-like product. The paste-like product was applied on a copper
foil as a collector, followed by drying, and dried at 150.degree.
C. under reduced pressure.
[0274] Thus, there was obtained an electrode structural body as an
anode 601.
[0275] 2. Preparation of Cathode 603:
[0276] 90 parts of a powdery lithium cobaltate, 5 parts of an
acetylene black, and 5 parts of a powdery polyvinylidene fluoride
were mixed to obtain a mixture. The mixture was mixed with 100
parts of N-methyl-2-pyrroidone, followed by being stirred, to
obtain a paste-like product.
[0277] The paste-like product obtained in the above was applied on
an aluminum foil as a collector, followed by drying, and dried at
150.degree. C. under reduced pressure.
[0278] Thus, there was obtained a cathode 603.
[0279] 3. Preparation of an Electrolyte Solution:
[0280] Ethylene carbonate (EC) whose moisture having been
sufficiently removed and dimethyl carbonate (DMC) whose moisture
having been sufficiently removed were mixed at an equivalent mixing
ratio, to obtain a solvent.
[0281] 1 M (mol/1) of lithium tetrafluoroborate (LiBF.sub.4) was
dissolved in the solvent obtained in the above to obtain an
electrolyte solution.
[0282] 4. Provision of a Separator 602:
[0283] There was provided a separator comprising a polyethylene
film member having a number of micropores.
[0284] By introducing the electrolyte solution at a later stage,
the electrolyte solution becomes to retain in the micropores of the
separator, where the separator having the electrolyte solution
therein functions as the ion conductor.
[0285] 5. Fabrication of a Rechargeable Lithium Battery:
[0286] The fabrication of a rechargeable lithium battery was
conducted in a dry atmosphere controlled with respect to moisture
with a dew point of less than -50.degree. C.
[0287] The separator 602 was sandwiched between the anode 601 and
the cathode 603, and the resultant was inserted in a cathode can
605 made of titanium clad stainless steel. Then, the electrolyte
solution was introduced into the cathode can such that it was
retained in the separator. Thereafter, the resultant was sealed
using an anode cap 604 made of titanium clad stainless steel and an
insulating packing 606 made of polypropylene.
[0288] Thus, there was prepared a rechargeable lithium battery
having such cross-sectional structure as shown in FIG. 6.
[0289] This rechargeable battery was made to be of an anode
capacity-controlled type in that the cathode capacity is larger
than the anode capacity.
Evaluation of Battery Characteristics
[0290] For the rechargeable lithium battery obtained in this
example, evaluation was conducted with respect to battery
characteristics, i.e., battery capacity, charge-and-discharge
Coulombic efficiency, and charging and discharging cycle life,
obtained by performing alternately charging and discharging, in the
following manner.
[0291] (1). Capacity Test:
[0292] The capacity test was conducted through the following
charging and discharging cycle test. That is, a cycle in that
charging is performed for 10 hours wherein first charging is
performed with a constant electric current of a value of 0.1 C (an
electric current of 0.1 time a value of capacity/time) obtained on
the basis of an electric capacitance calculated from the cathode
active material of the rechargeable lithium battery, when the
battery voltage reaches 4.2 V, the first charging is terminated,
followed by performing second charging with a constant voltage of
4.2; a pause for 10 minutes is taken; then discharging is performed
with a constant electric current of aforesaid value of 0.1 C (the
electric current of 0.1 time the value of the capacity/the time)
until the battery voltage reaches 2.8 V; and a pause for 10 minutes
is taken, was repeated three times. The battery capacity was
evaluated on the basis of a value obtained from a discharged
electricity quantity provided in the third cycle.
[0293] (2). Charge-and-Discharge Coulombic Efficiency:
[0294] The charge-and-discharge Coulombic efficiency was obtained
in the following manner. That is, a proportion of the discharged
electricity quantity to the charged electricity quantity in the
above capacity test was calculated. The resultant proportion value
was made to be a charge-and-discharge Coulombic efficiency for the
battery.
[0295] (3). Charging and Discharging Cycle Life:
[0296] The charging and discharging cycle life was evaluated in the
following manner. The charging and discharging cycle test was
conducted by repeating a cycle of alternately performing charging
and discharging with a constant electric current of 0.5 C (an
electric current of 0.5 time a value of the capacity/the time) on
the basis of the discharged electricity quantity in the third cycle
in the above capacity test and taking a pause for 10 minutes. And
the number of the charging and discharging cycles when the initial
battery capacity became less than 60% was made to be a charging and
discharging cycle life for the battery.
[0297] In the above evaluation, the cut-off voltage upon the
charging was made to be 4.5 V, and that upon the discharging was
made to be 2.5 V.
[0298] The evaluated results obtained in the above are collectively
shown in Table 1.
EXAMPLE 2
[0299] In this example, there was prepared a rechargeable lithium
battery having such cross-sectional structure as shown in FIG. 6 by
repeating the procedures of Example 1 except that the anode was
prepared using a Sn--Co amorphous alloy material (particulate)
prepared as will be described below.
[0300] The rechargeable lithium battery obtained in this example
was evaluated with respect to its battery characteristics in the
same manner as in Example 1. The evaluated results are shown in
Table 1.
[0301] Preparation of Anode 601:
[0302] (1). Preparation of an Alloy Powder (Particulate) as an
Electrode Material:
[0303] 5.3 parts of a pentahydrate of tin (IV) chloride as the
metal compound capable of being alloyed with lithium, 10.7 parts of
a hexahydrate of cobalt (II) chloride as the transition metal
compound, 75.0 parts of a dehydrate of trisodium citrate, 8.8 parts
of ethylenediaminetetraacetic acid, and 8.8 parts of a potassium
acetate respectively as the complexing agent were mixed with 100
parts of water as the solvent and sufficiently stirred to obtain a
mixed solution. The mixed solution was introduced into the reaction
vessel 201 (provided with the starting material introduction device
202, the reflux device 203, the gas introduction pipe 204, the
agitator 205, and the temperature controlling equipment 206) shown
in FIG. 2 through the starting material introduction device, and in
order to maintain the inside of the reaction vessel in a nitrogen
gas atmosphere, nitrogen gas was introduced into the reaction
vessel through the gas introduction pipe, where excessive nitrogen
gas was exhausted to the outside of the system through the reflux
device. The reaction vessel having the mixed solution therein was
heated to 70.degree. C. by means of the temperature controlling
equipment (water bath), and the mixed solution in the reaction
vessel was sufficiently stirred by means of the agitator.
[0304] Here, a specimen of the mixed solution treated in the above
was subjected to analysis by means of a visible-ultraviolet
absorption spectrum analyzer. As a result, as well as in Example 1,
it was found that a complex formed by the metal of the metal
compound (capable of being alloyed with lithium) and the complexing
agent and a complex formed by the transition metal of the
transition metal compound and the complexing agent are contained in
the mixed solution.
[0305] Then, a solution obtained by dissolving 23.1 parts of a
titanium (III) chloride as the reducing agent in 73.3 parts of
water was heated to 70.degree. C. and added to the mixed solution
in the reaction vessel through the starting material introduction
device, followed by being sufficiently stirred. This adding and
mixing step was performed within one minute. The pH value of the
solution in the reaction vessel was measured. As a result, the
solution was found to have a pH value of 0.1.
[0306] Thereafter, a potassium hydroxide aqueous solution of 8N was
added to the solution in the reaction vessel through the starting
material introduction device while stirring the solution, so that
the pH value of the solution became to be 8.0, and the solution in
the reaction vessel was subjected to a heat treatment at 70.degree.
C. for 30 minutes. The adding and mixing step of the potassium
hydroxide aqueous solution here was performed within one
minute.
[0307] Thereafter, the content in the reaction vessel was taken out
from the vessel, and it was washed with water, and vacuum-dried at
50.degree. C. Thus, there was obtained a product comprising a
Sn--Co alloy power.
[0308] A specimen of the resultant alloy powder was subjected to
analysis by means of X-ray microanalysis (XMA). As a result, only
Sn and Co were detected without other elements being detected.
Then, the specimen was subjected to analysis by means of
inductively coupled plasma emission analysis (ICP). As a result,
the content of Sn and that of Co were found to be 75% and 25%
respectively in terms of the atom number content.
[0309] Separately, using an X-ray diffraction device RINT 2000
(produced by Kabusiki Kaisha RIGAKU), a specimen of the resultant
alloy powder was subjected to wide angle X-ray diffraction analysis
using K.alpha.-rays of Cu as a radiation source, which gave peaks
having a widened half width appeared in a region of
2.theta.=25.degree. to 50.degree.. And there were observed two main
peaks one at 2.theta.=30.4.degree. and another at
2.theta.=43.0.degree. in the X-ray diffraction chart, having a half
width of 0.6.degree. and that of 0.8.degree., respectively. The
presence of these peaks having a wide half width indicates that the
resultant alloy powder is amorphous. Separately, calculation was
carried out on the basis of the half widths and the diffraction
angles of these peaks and in accordance with the foregoing
Scherrer's equation. As a result, there were obtained a crystallite
size of 14 nm and another crystallite size of 11 nm.
[0310] In addition, a specimen of the resultant alloy powder was
subjected to measurement of particle size distribution by means of
a particle size distribution measuring equipment using a laser
scattering method. As a result, it was found to have an average
particle size of 0.4 .mu.m and a particle size distribution of 0.06
to 0.9 .mu.m.
[0311] Further, a specimen of the resultant alloy powder was
examined by means of a scanning electron microscope. As a result,
it was found that an average value of the [longest length of
particle]/[shortest length of particle] is 1.4. From this result,
the resultant alloy powder was found to comprise spherical
particles.
[0312] Further in addition, a specimen of the resultant alloy
powder was subjected to measurement of specific surface area by
means of a BET method using nitrogen gas. As a result, it was found
to have a specific surface area of 75 m.sup.2/g.
[0313] (2). Preparation of an Electrode Structural Body as an Anode
601:
[0314] 90 parts of the Sn--Co alloy powder obtained in the above, 5
parts of an acetylene black powder as an electrically conductive
auxiliary and 5 parts of a polyvinylidene fluoride powder were
mixed to obtain a mixture, and the mixture was mixed with 100 parts
of N-methyl-2-pyrrolidone as a solvent, and stirred to obtain a
paste-like product. The paste-like product was applied on a copper
foil as a collector, followed by drying, and dried at 150.degree.
C. under reduced pressure.
[0315] Thus, there was obtained an electrode structural body as an
anode 601.
EXAMPLE 3
[0316] In this example, there was prepared a rechargeable lithium
battery having such cross-sectional structure as shown in FIG. 6 by
repeating the procedures of Example 1 except that the anode was
prepared using a Sn--Ni amorphous alloy material (particulate)
prepared as will be described below.
[0317] The rechargeable lithium battery obtained in this example
was evaluated with respect to its battery characteristics in the
same manner as in Example 1. The evaluated results are shown in
Table 1.
[0318] Preparation of Anode 601:
[0319] (1). Preparation of an Alloy Powder (Particulate) as an
Electrode Material:
[0320] 11 parts of a pentahydrate of tin (IV) chloride as the metal
compound capable of being alloyed with lithium, 7.1 parts of a
hexahydrate of nickel (II) chloride as the transition metal
compound, 75.0 parts of a dihydrate of trisodium citrate, 8.8 parts
of ethylenediaminetetraacetic acid, and 8.8 parts of a potassium
acetate respectively as the complexing agent were mixed with 100
parts of water as the solvent and sufficiently stirred to obtain a
mixed solution. The mixed solution was introduced into the reaction
vessel 201 (provided with the starting material introduction device
202, the ref lux device 203, the gas introduction pipe 204, the
agitator 205, and the temperature controlling equipment 206) shown
in FIG. 2 through the starting material introduction device, and in
order to maintain the inside of the reaction vessel in an inert gas
atmosphere, argon gas was introduced into the reaction vessel
through the gas introduction pipe, where excessive argon gas was
exhausted to the outside of the system through the reflux device.
The reaction vessel having the mixed solution therein was heated to
70.degree. C. by means of the temperature controlling equipment
(water bath), and the mixed solution in the reaction vessel was
sufficiently stirred by means of the agitator.
[0321] Here, a specimen of the mixed solution treated in the above
was subjected to analysis by means of a visible-ultraviolet
absorption spectrum analyzer. As a result, as well as in Example 1,
it was found that a complex formed by the metal of the metal
compound (capable of being alloyed with lithium) and the complexing
agent and a complex formed by the transition metal of the
transition metal compound and the complexing agent are contained in
the mixed solution.
[0322] Then, a solution obtained by dissolving 27.8 parts of a
titanium (III) chloride as the reducing agent in 87.9 parts of
water was heated to 70.degree. C. and added to the mixed solution
in the reaction vessel through the starting material introduction
device, followed by being sufficiently stirred. This adding and
mixing step was performed within one minute. The pH value of the
solution in the reaction vessel was measured. As a result, the
solution was found to have a pH value of 0.05.
[0323] Thereafter, a potassium hydroxide aqueous solution of 8N was
added to the solution in the reaction vessel through the starting
material introduction device while stirring the solution, so that
the pH value of the solution became to be 7.0, and the solution in
the reaction vessel was subjected to a heat treatment at 90.degree.
C. for 2 hours. The adding and mixing step of the potassium
hydroxide aqueous solution here was performed within one
minute.
[0324] Thereafter, the content in the reaction vessel was taken out
from the vessel, and it was washed with water, and vacuum-dried at
50.degree. C. Thus, there was obtained a product comprising a
Sn--Ni alloy power.
[0325] A specimen of the resultant alloy powder was subjected to
analysis by means of X-ray microanalysis (XMA). As a result, Sn,
Ni, Ti, and O were detected without other elements being detected.
Then, the specimen was subjected to analysis by means of
inductively coupled plasma emission analysis (ICP). As a result,
the content of Sn, that of Ni, that of Ti, and that of O were found
to be 48%, 39%, 5% and 8% respectively in terms of the atom number
content.
[0326] Separately, using an X-ray diffraction device RINT 2000
(produced by Kabusiki Kaisha RIGAKU), a specimen of the resultant
alloy powder was subjected to wide angle X-ray diffraction analysis
using K.alpha.-rays of Cu as a radiation source, which gave peaks
having a widened half width appeared in a region of
2.theta.=25.degree. to 50.degree.. And there were observed two main
peaks one at 2.theta.=30.6.degree. and another at
2.theta.=43.7.degree. in the X-ray diffraction chart, having a half
width of 0.8.degree. and that of 0.9.degree., respectively. The
presence of these peaks having a wide half width indicates that the
resultant alloy powder is amorphous. Separately, calculation was
carried out on the basis of the half widths and the diffraction
angles of these peaks and in accordance with the foregoing
Scherrer's equation. As a result, there were obtained a crystallite
size of 11 nm and another crystallite size of 10 nm.
[0327] In addition, a specimen of the resultant alloy powder was
subjected to measurement of particle size distribution by means of
a particle size distribution measuring equipment using a laser
scattering method. As a result, it was found to have an average
particle size of 0.49 .mu.m and a particle size distribution of
0.10 to 1.0 .mu.m.
[0328] Further, a specimen of the resultant alloy powder was
examined by means of a scanning electron microscope. As a result,
it was found that an average value of the [longest length of
particle]/[shortest length of particle] is 1.5. From this result,
the resultant alloy powder was found to comprise spherical
particles.
[0329] Further in addition, a specimen of the resultant alloy
powder was subjected to measurement of specific surface area by
means of a BET method using nitrogen gas. As a result, it was found
to have a specific surface area of 52 m.sup.2/g.
[0330] (2). Preparation of an Electrode Structural Body as an Anode
601:
[0331] 90 parts of the Sn--Ni alloy powder obtained in the above
was introduced into a planetary ball mill, where it was ground for
one hour. The resultant, 5 parts of a graphite powder as an
electrically conductive auxiliary, 2 parts of polyvinyl alcohol,
and 3 parts of carboxymethylcellulose were mixed to obtain a
mixture, and the mixture was mixed with 100 parts of water as a
solvent, and stirred to obtain a paste-like product. The paste-like
product was applied on a copper foil as a collector, followed by
drying, and dried at 150.degree. C. under reduced pressure.
[0332] Thus, there was obtained an electrode structural body as an
anode 601.
EXAMPLE 4
[0333] In this example, there was prepared a rechargeable lithium
battery having such cross-sectional structure as shown in FIG. 6 by
repeating the procedures of Example 1 except that the anode was
prepared using a Sn--Ni amorphous alloy material (particulate)
prepared as will be described below.
[0334] The rechargeable lithium battery obtained in this example
was evaluated with respect to its battery characteristics in the
same manner as in Example 1. The evaluated results are shown in
Table 1.
[0335] Preparation of Anode 601:
[0336] (1). Preparation of an Alloy Powder (Particulate) as an
Electrode Material:
[0337] 5.3 parts of a pentahydrate of tin (IV) chloride as the
metal compound capable of being alloyed with lithium, 10.7 parts of
a hexahydrate of nickel (II) chloride as the transition metal
compound, 75.0 parts of a dihydrate of trisodium citrate, and 8.8
parts of ethylenediaminetetraacetic acid respectively as the
complexing agent were mixed with 100 parts of water as the solvent
and sufficiently stirred to obtain a mixed solution. The mixed
solution was introduced into the reaction vessel 201 (provided with
the starting material introduction device 202, the reflux device
203, the gas introduction pipe 204, the agitator 205, and the
temperature controlling equipment 206) shown in FIG. 2 through the
starting material introduction device, and in order to maintain the
inside of the reaction vessel in a nitrogen gas atmosphere,
nitrogen gas was introduced into the reaction vessel through the
gas introduction pipe, where excessive nitrogen gas was exhausted
to the outside of the system through the reflux device. The
reaction vessel having the mixed solution therein was heated to
36.degree. C. by means of the temperature controlling equipment
(water bath), and the mixed solution in the reaction vessel was
sufficiently stirred by means of the agitator.
[0338] Here, a specimen of the mixed solution treated in the above
was subjected to analysis by means of a visible-ultraviolet
absorption spectrum analyzer. As a result, as well as in Example 1,
it was found that a complex formed by the metal of the metal
compound (capable of being alloyed with lithium) and the complexing
agent and a complex formed by the transition metal of the
transition metal compound and the complexing agent are contained in
the mixed solution.
[0339] Then, a solution obtained by dissolving 23.1 parts of a
titanium (III) chloride as the reducing agent in 73.3 parts of
water was heated to 36.degree. C. and added to the mixed solution
in the reaction vessel through the starting material introduction
device, followed by being sufficiently stirred. This adding and
mixing step was performed within one minute. The pH value of the
solution in the reaction vessel was measured. As a result, the
solution was found to have a pH value of 0.1.
[0340] Thereafter, a potassium hydroxide aqueous solution of 8N was
added to the solution in the reaction vessel through the starting
material introduction device while stirring the solution, so that
the pH value of the solution became to be 10.0, and the solution in
the reaction vessel was subjected to a heat treatment at 36.degree.
C. for 15 minutes. The adding and mixing step of the potassium
hydroxide aqueous solution here was performed within one
minute.
[0341] Thereafter, the content in the reaction vessel was taken out
from the vessel, and it was washed with water, and vacuum-dried at
50.degree. C. Thus, there was obtained a product comprising a
Sn--Ni alloy power.
[0342] A specimen of the resultant alloy powder was subjected to
analysis by means of X-ray microanalysis (XMA). As a result, only
Sn and Ni were detected without other elements being detected.
Then, the specimen was subjected to analysis by means of
inductively coupled plasma emission analysis (ICP). As a result,
the content of Sn and that of Ni were found to be 75% and 25%
respectively in terms of the atom number content.
[0343] Separately, using an X-ray diffraction device RINT 2000
(produced by Kabusiki Kaisha RIGAKU), a specimen of the resultant
alloy powder was subjected to wide angle X-ray diffraction analysis
using K.alpha.-rays of Cu as a radiation source, which gave peaks
having a widened half width appeared in a region of
2.theta.=25.degree. to 50.degree.. And there were observed two main
peaks one at 2.theta.=30.6.degree. and another at
2.theta.=43.7.degree. in the X-ray diffraction chart, having a half
width of 0.6.degree. and that of 0.7.degree., respectively. The
presence of these peaks having a wide half width indicates that the
resultant alloy powder is amorphous. Separately, calculation was
carried out on the basis of the half widths and the diffraction
angles of these peaks and in accordance with the foregoing
Scherrer's equation. As a result, there were obtained a crystallite
size of 14 nm and another crystallite size of 13 nm.
[0344] In addition, a specimen of the resultant alloy powder was
subjected to measurement of particle size distribution by means of
a particle size distribution measuring equipment using a laser
scattering method. As a result, it was found to have an average
particle size of 0.24 .mu.m and a particle size distribution of
0.05 to 0.8 .mu.m.
[0345] Further, a specimen of the resultant alloy powder was
examined by means of a scanning electron microscope. As a result,
it was found that an average value of the [longest length of
particle]/[shortest length of particle] is 1.2. From this result,
the resultant alloy powder was found to comprise spherical
particles.
[0346] Further in addition, a specimen of the resultant alloy
powder was subjected to measurement of specific surface area by
means of a BET method using nitrogen gas. As a result, it was found
to have a specific surface area of 95 m.sup.2/g.
[0347] (2). Preparation of an Electrode Structural Body as an Anode
601:
[0348] 90 parts of the Sn--Ni alloy powder obtained in the above
was introduced into a planetary ball mill, where it was ground for
one hour. The resultant, 5 parts of an acetylene black powder as an
electrically conductive auxiliary and 5 parts of a polyvinylidene
fluoride powder were mixed to obtain a mixture, and the mixture was
mixed with 100 parts of N-methyl-2-pyrrolidone as a solvent, and
stirred to obtain a paste-like product. The paste-like product was
applied on a copper foil as a collector, followed by drying, and
dried at 150.degree. C. under reduced pressure.
[0349] Thus, there was obtained an electrode structural body as an
anode 601.
EXAMPLE 5
[0350] In this example, there was prepared a rechargeable lithium
battery having such cross-sectional structure as shown in FIG. 6 by
repeating the procedures of Example 1 except that the anode was
prepared using a Sn--Ni amorphous alloy material (particulate)
prepared as will be described below.
[0351] The rechargeable lithium battery obtained in this example
was evaluated with respect to its battery characteristics in the
same manner as in Example 1. The evaluated results are shown in
Table 1.
[0352] Preparation of Anode 601:
[0353] (1). Preparation of an Alloy Powder (Particulate) as an
Electrode Material:
[0354] 11.0 parts of a pentahydrate of tin (IV) chloride as the
metal compound capable of being alloyed with lithium, 7.1 parts of
a hexahydrate of nickel (II) chloride as the transition metal
compound, 50.0 parts of a dihydrate of trisodium citrate, and 2.0
parts of a sodium hydrogenphosphate respectively as the complexing
agent were mixed with 100 parts of water as the solvent and
sufficiently stirred to obtain a mixed solution. The mixed solution
was introduced into the reaction vessel 201 (provided with the
starting material introduction device 202, the reflux device 203,
the gas introduction pipe 204, the agitator 205, and the
temperature controlling equipment 206) shown in FIG. 2 through the
starting material introduction device, and in order to maintain the
inside of the reaction vessel in a nitrogen gas atmosphere,
nitrogen gas was introduced into the reaction vessel through the
gas introduction pipe, where excessive nitrogen gas was exhausted
to the outside of the system through the ref lux device. The
reaction vessel having the mixed solution therein was heated to
70.degree. C. by means of the temperature controlling equipment
(water bath), and the mixed solution in the reaction vessel was
sufficiently stirred by means of the agitator.
[0355] Here, a specimen of the mixed solution treated in the above
was subjected to analysis by means of a visible-ultraviolet
absorption spectrum analyzer. As a result, as well as in Example 1,
it was found that a complex formed by the metal of the metal
compound (capable of being alloyed with lithium) and the complexing
agent and a complex formed by the transition metal of the
transition metal compound and the complexing agent are contained in
the mixed solution.
[0356] Then, a solution obtained by dissolving 45.0 parts of a
sodium sulfite as the reducing agent in 168.9 parts of water was
heated to 70.degree. C. and added to the mixed solution in the
reaction vessel through the starting material introduction device
while stirring the mixed solution in the reaction vessel. And the
solution in the reaction vessel was subjected to a heat treatment
at 70.degree. C. for 30 minutes. This adding and mixing step was
performed within one minute. The pH value of the solution in the
reaction vessel was measured. As a result, the solution was found
to have a pH value of 5.7.
[0357] Thereafter, the content in the reaction vessel was taken out
from the vessel, and it was washed with water, and vacuum-dried at
50.degree. C. Thus, there was obtained a product comprising a
Sn--Ni alloy power.
[0358] A specimen of the resultant alloy powder was subjected to
analysis by means of X-ray microanalysis (XMA). As a result, only
Sn, Ni and S were detected without other elements being detected.
Then, the specimen was subjected to analysis by means of
inductively coupled plasma emission analysis (ICP). As a result,
the content of Sn, that of Ni, and that of S were found to be 58%,
40%, and 2% respectively in terms of the atom number content.
[0359] Separately, using an X-ray diffraction device RINT 2000
(produced by Kabusiki Kaisha RIGAKU), a specimen of the resultant
alloy powder was subjected to wide angle X-ray diffraction analysis
using K.alpha.-rays of Cu as a radiation source, which gave peaks
having a widened half width appeared in a region of
2.theta.=25.degree. to 50.degree.. And there were observed two main
peaks one at 2.theta.=30.4.degree. and another at
2.theta.=43.6.degree. in the X-ray diffraction chart, having a half
width of 0.5.degree. and that of 0.6.degree., respectively. The
presence of these peaks having a wide half width indicates that the
resultant alloy powder is amorphous. Separately, calculation was
carried out on the basis of the half widths and the diffraction
angles of these peaks and in accordance with the foregoing
Scherrer's equation. As a result, there were obtained a crystallite
size of 17 nm and another crystallite size of 15 nm.
[0360] In addition, a specimen of the resultant alloy powder was
subjected to measurement of particle size distribution by means of
a particle size distribution measuring equipment using a laser
scattering method. As a result, it was found to have an average
particle size of 0.4 .mu.m and a particle size distribution of 0.11
to 1.1 .mu.m.
[0361] Further, a specimen of the resultant alloy powder was
examined by means of a scanning electron microscope. As a result,
it was found that an average value of the [longest length of
particle]/[shortest length of particle] is 1.3. From this result,
the resultant alloy powder was found to comprise spherical
particles.
[0362] Further in addition, a specimen of the resultant alloy
powder was subjected to measurement of specific surface area by
means of a BET method using nitrogen gas. As a result, it was found
to have a specific surface area of 32 m.sup.2/g.
[0363] (2). Preparation of an Electrode Structural Body as an Anode
601:
[0364] 90 parts of the Sn--Ni alloy powder obtained in the above, 5
parts of an acetylene black powder as an electrically conductive
auxiliary, 2 parts of polyvinyl alcohol and 5 parts of
carboxymethylcellulose were mixed to obtain a mixture, and the
mixture was mixed with 100 parts of water as a solvent, and stirred
to obtain a paste-like product. The paste-like product was applied
on a copper foil as a collector, followed by drying, and dried at
150.degree. C. under reduced pressure.
[0365] Thus, there was obtained an electrode structural body as an
anode 601.
EXAMPLE 6
[0366] In this example, there was prepared a rechargeable lithium
battery having such cross-sectional structure as shown in FIG. 6 by
repeating the procedures of Example 1 except that the anode was
prepared using a Sn--Ni amorphous alloy material (particulate)
prepared as will be described below.
[0367] The rechargeable lithium battery obtained in this example
was evaluated with respect to its battery characteristics in the
same manner as in Example 1. The evaluated results are shown in
Table 1.
[0368] Preparation of Anode 601:
[0369] (1). Preparation of an Alloy Powder (Particulate) as an
Electrode Material:
[0370] 11.2 parts of a pentahydrate of tin (IV) chloride as the
metal compound capable of being alloyed with lithium, 2.5 parts of
a hexahydrate of nickel (II) chloride as the transition metal
compound, 37.5 parts of a dihydrate of trisodium citrate, and 2
parts of a sodium laurate respectively as the complexing agent were
mixed with a mixed solvent comprising 50 parts of water and 50
parts of ethanol as the solvent and sufficiently stirred to obtain
a mixed solution. The mixed solution was introduced into the
reaction vessel 201 (provided with the starting material
introduction device 202, the reflux device 203, the gas
introduction pipe 204, the agitator 205, and the temperature
controlling equipment 206) shown in FIG. 2 through the starting
material introduction device, and in order to maintain the inside
of the reaction vessel in an inert gas atmosphere, argon gas was
introduced into the reaction vessel through the gas introduction
pipe, where excessive argon gas was exhausted to the outside of the
system through the reflux device. The reaction vessel having the
mixed solution therein was heated to 25.degree. C. by means of the
temperature controlling equipment (water bath), and the mixed
solution in the reaction vessel was sufficiently stirred by means
of the agitator.
[0371] Here, a specimen of the mixed solution treated in the above
was subjected to analysis by means of a visible-ultraviolet
absorption spectrum analyzer. As a result, as well as in Example 1,
it was found that a complex formed by the metal of the metal
compound (capable of being alloyed with lithium) and the complexing
agent and a complex formed by the transition metal of the
transition metal compound and the complexing agent are contained in
the mixed solution.
[0372] Then, a solution obtained by dissolving 46.3 parts of a
titanium (III) chloride as the reducing agent in 103.7 parts of
water was heated to 25.degree. C. and added to the mixed solution
in the reaction vessel through the starting material introduction
device, followed by being sufficiently stirred. This adding and
mixing step was performed within one minute. The pH value of the
solution in the reaction vessel was measured. As a result, the
solution was found to have a pH value of 0.03.
[0373] Thereafter, a potassium hydroxide aqueous solution of 8N was
added to the solution in the reaction vessel through the starting
material introduction device while stirring the solution, so that
the pH value of the solution became to be 7.0, and the solution in
the reaction vessel was subjected to a heat treatment at 25.degree.
C. for 2 hours. The adding and mixing step of the potassium
hydroxide aqueous solution here was performed within one
minute.
[0374] Thereafter, the content in the reaction vessel was taken out
from the vessel, and it was washed with water, and vacuum-dried at
50.degree. C. Thus, there was obtained a product comprising a
Sn--Ni alloy power.
[0375] A specimen of the resultant alloy powder was subjected to
analysis by means of X-ray microanalysis (XMA). As a result, Sn,
Ni, Ti, and O were detected without other elements being detected.
Then, the specimen was subjected to analysis by means of
inductively coupled plasma emission analysis (ICP). As a
result,,the content of Sn, that of Ni, that of Ti, and that of O
were found to be 68%, 18%, 15% and 9% respectively in terms of the
atom number content.
[0376] Separately, using an X-ray diffraction device RINT 2000
(produced by Kabusiki Kaisha RIGAKU), a specimen of the resultant
alloy powder was subjected to wide angle X-ray diffraction analysis
using K.alpha.-rays of Cu as a radiation source, which gave peaks
having a widened half width appeared in a region of
2.theta.=25.degree. to 50.degree.. And there were observed two main
peaks one at 2.theta.=30.6.degree. and another at
2.theta.=43.7.degree. in the X-ray diffraction chart, having a half
width of 0.4.degree. and that of 0.5.degree., respectively. The
presence of these peaks having a wide half width indicates that the
resultant alloy powder is amorphous. Separately, calculation was
carried out on the basis of the half widths and the diffraction
angles of these peaks and in accordance with the foregoing
Scherrer's equation. As a result, there were obtained a crystallite
size of 21 nm and another crystallite size of 18 nm.
[0377] In addition, a specimen of the resultant alloy powder was
subjected to measurement of particle size distribution by means of
a particle size distribution measuring equipment using a laser
scattering method. As a result, it was found to have an average
particle size of 0.33 .mu.m and a particle size distribution of
0.05 to 2.1 .mu.m.
[0378] Further, a specimen of the resultant alloy powder was
examined by means of a scanning electron microscope. As a result,
it was found that an average value of the [longest length of
particle]/[shortest length of particle] is 1.3. From this result,
the resultant alloy powder was found to comprise spherical
particles.
[0379] Further in addition, a specimen of the resultant alloy
powder was subjected to measurement of specific surface area by
means of a BET method using nitrogen gas. As a result, it was found
to have a specific surface area of 31 m.sup.2/g.
[0380] (2). Preparation of an Electrode Structural Body as an Anode
601:
[0381] 90 parts of the Sn--Ni alloy powder obtained in the above, 5
parts of a graphite powder as an electrically conductive auxiliary,
2 parts of polyvinyl alcohol, and 3 parts of carboxymethylcellulose
were mixed to obtain a mixture, and the mixture was mixed with 100
parts of water as a solvent, and stirred to obtain a paste-like
product. The paste-like product was applied on a copper foil as a
collector, followed by drying, and dried at 150.degree. C. under
reduced pressure.
[0382] Thus, there was obtained an electrode structural body as an
anode 601.
EXAMPLE 7
[0383] In this example, there was prepared a rechargeable lithium
battery having such cross-sectional structure as shown in FIG. 6 by
repeating the procedures of Example 1 except that the anode was
prepared using a Sn--Ni amorphous alloy material (particulate)
prepared as will be described below.
[0384] The rechargeable lithium battery obtained in this example
was evaluated with respect to its battery characteristics in the
same manner as in Example 1. The evaluated results are shown in
Table 1.
[0385] Preparation of Anode 601:
[0386] (1). Preparation of an Alloy Powder (Particulate) as an
Electrode Material:
[0387] 3.6 parts of a tin (II) nitrate as the metal compound
capable of being alloyed with lithium, 13.7 parts of a nickel (II)
nitrate as the transition metal compound, and 26.5 parts of a
dihydrate of trisodium citrate as the complexing agent were mixed
with 100 parts of water as the solvent and sufficiently stirred to
obtain a mixed solution. The mixed solution was introduced into the
reaction vessel 201 (provided with the starting material
introduction device 202, the reflux device 203, the gas
introduction pipe 204, the agitator 205, and the temperature
controlling equipment 206) shown in FIG. 2 through the starting
material introduction device, and in order to maintain the inside
of the reaction vessel in an inert gas atmosphere, argon gas was
introduced into the reaction vessel through the gas introduction
pipe, where excessive argon gas was exhausted to the outside of the
system through the reflux device. The reaction vessel having the
mixed solution therein was heated to 40.degree. C. by means of the
temperature controlling equipment (water bath), and the mixed
solution in the reaction vessel was sufficiently stirred by means
of the agitator.
[0388] Here, a specimen of the mixed solution treated in the above
was subjected to analysis by means of a visible-ultraviolet
absorption spectrum analyzer. As a result, as well as in Example 1,
it was found that a complex formed by the metal of the metal
compound (capable of being alloyed with lithium) and the complexing
agent and a complex formed by the transition metal of the
transition metal compound and the complexing agent are contained in
the mixed solution.
[0389] Then, a solution obtained by dissolving 83.4 parts of a
titanium (III) chloride as the reducing agent in 264 parts of water
was heated to 25.degree. C. and added to the mixed solution in the
reaction vessel through the starting material introduction device,
followed by being sufficiently stirred. This adding and mixing step
was performed within one minute. The pH value of the solution in
the reaction vessel was measured. As a result, the solution was
found to have a pH value of 0.02.
[0390] Thereafter, a potassium hydroxide aqueous solution of 8N was
added to the solution in the reaction vessel through the starting
material introduction device while stirring the solution, so that
the pH value of the solution became to be 7.0, and the solution in
the reaction vessel was subjected to a heat treatment at 40.degree.
C. for 2 hours. The adding and mixing step of the potassium
hydroxide aqueous solution here was performed within one
minute.
[0391] Thereafter, the content in the reaction vessel was taken out
from the vessel, and it was washed with water, and vacuum-dried at
50.degree. C. Thus, there was obtained a product comprising a
Sn--Ni alloy power.
[0392] A specimen of the resultant alloy powder was subjected to
analysis by means of X-ray microanalysis (XMA). As a result, Sn,
Ni, Ti, and O were detected without other elements being detected.
Then, the specimen was subjected to analysis by means of
inductively coupled plasma emission analysis (ICP). As a result,
the content of Sn, that of Ni, that of Ti, and that of O were found
to be 47%, 30%, 23% and 10% respectively in terms of the atom
number content.
[0393] Separately, using an X-ray diffraction device RINT 2000
(produced by Kabusiki Kaisha RIGAKU), a specimen of the resultant
alloy powder was subjected to wide angle X-ray diffraction analysis
using K.alpha.-rays of Cu as a radiation source, which gave peaks
having a widened half width appeared in a region of
2.theta.=25.degree. to 50.degree.. And there were observed two main
peaks one at 2.theta.=30.6.degree. and another at
2.theta.=43.7.degree. in the X-ray diffraction chart, having a half
width of 0.2.degree. and that of 0.3.degree., respectively. The
presence of these peaks having a wide half width indicates that the
resultant alloy powder is amorphous. Separately, calculation was
carried out on the basis of the half widths and the diffraction
angles of these peaks and in accordance with the foregoing
Scherrer's equation. As a result, there were obtained a crystallite
size of 43 nm and another crystallite size of 30 nm.
[0394] In addition, a specimen of the resultant alloy powder was
subjected to measurement of particle size distribution by means of
a particle size distribution measuring equipment using a laser
scattering method. As a result, it was found to have an average
particle size of 1.12 .mu.m and a particle size distribution of
0.20 to 19.0 .mu.m.
[0395] Further, a specimen of the resultant alloy powder was
examined by means of a scanning electron microscope. As a result,
it was found that an average value of the [longest length of
particle]/[shortest length of particle] is 1.8. From this result,
the resultant alloy powder was found to comprise spherical
particles.
[0396] Further in addition, a specimen of the resultant alloy
powder was subjected to measurement of specific surface area by
means of a BET method using nitrogen gas. As a result, it was found
to have a specific surface area of 11 m.sup.2/g.
[0397] (2). Preparation of an Electrode Structural Body as an Anode
601:
[0398] 90 parts of the Sn--Ni alloy powder obtained in the above, 5
parts of a graphite powder as an electrically conductive auxiliary,
2 parts of polyvinyl alcohol, and 3 parts of carboxymethylcellulose
were mixed to obtain a mixture, and the mixture was mixed with 100
parts of water as a solvent, and stirred to obtain a paste-like
product. The paste-like product was applied on a copper foil as a
collector, followed by drying, and dried at 150.degree. C. under
reduced pressure.
[0399] Thus, there was obtained an electrode structural body as an
anode 601.
EXAMPLE 8
[0400] In this example, there was prepared a rechargeable lithium
battery having such cross-sectional structure as shown in FIG. 6 by
repeating the procedures of Example 1 except that the anode was
prepared using a Sn--Ni--Co amorphous alloy material (particulate)
prepared as will be described below.
[0401] The rechargeable lithium battery obtained in this example
was evaluated with respect to its battery characteristics in the
same manner as in Example 1. The evaluated results are shown in
Table 1.
[0402] Preparation of Anode 601:
[0403] (1). Preparation of an Alloy Powder (Particulate) as an
Electrode Material:
[0404] 11 parts of a pentahydrate of tin (IV) chloride as the metal
compound capable of being alloyed with lithium, 3.6 parts of a
hexahydrate of nickel (II) chloride and 3.5 parts of a pentahydrate
of cobalt (II) chloride respectively as the transition metal
compound, 75.0 parts of a dihydrate of trisodium citrate, 8.8 parts
of ethylenediaminetetraacetic acid and 8.8 parts of potassium
acetate respectively as the complexing agent were mixed with 100
parts of water as the solvent and sufficiently stirred to obtain a
mixed solution. The mixed solution was introduced into the reaction
vessel 201 (provided with the starting material introduction device
202, the reflux device 203, the gas introduction pipe 204, the
agitator 205, and the temperature controlling equipment 206) shown
in FIG. 2 through the starting material introduction device, and in
order to maintain the inside of the reaction vessel in an inert gas
atmosphere, argon gas was introduced into the reaction vessel
through the gas introduction pipe, where excessive argon gas was
exhausted to the outside of the system through the reflux device.
The reaction vessel having the mixed solution therein was heated to
70.degree. C. by means of the temperature controlling equipment
(water bath), and the mixed solution in the reaction vessel was
sufficiently stirred by means of the agitator.
[0405] Here, a specimen of the mixed solution treated in the above
was subjected to analysis by means of a visible-ultraviolet
absorption spectrum analyzer. As a result, as well as in Example 1,
it was found that a complex formed by the metal of the metal
compound (capable of being alloyed with lithium) and the complexing
agent and a complex formed by the transition metal of the
transition metal compound and the complexing agent are contained in
the mixed solution.
[0406] Then, a solution obtained by dissolving 27.8 parts of a
titanium (III) chloride as the reducing agent in 87.9 parts of
water was heated to 70.degree. C. and added to the mixed solution
in the reaction vessel through the starting material introduction
device, followed by being sufficiently stirred. This adding and
mixing step was performed within one minute. The pH value of the
solution in the reaction vessel was measured. As a result, the
solution was found to have a pH value of 0.05.
[0407] Thereafter, a potassium hydroxide aqueous solution of 8N was
added to the solution in the reaction vessel through the starting
material introduction device while stirring the solution, so that
the pH value of the solution became to be 7.0, and the solution in
the reaction vessel was subjected to a heat treatment at 90.degree.
C. for 2 hours. The adding and mixing step of the potassium
hydroxide aqueous solution here was performed within one
minute.
[0408] Thereafter, the content in the reaction vessel was taken out
from the vessel, and it was washed with water, and vacuum-dried at
50.degree. C. Thus, there was obtained a product comprising a
Sn--Ni--Co alloy power.
[0409] A specimen of the resultant alloy powder was subjected to
analysis by means of X-ray microanalysis (XMA.). As a result, Sn,
Ni, and Co were detected without other elements being detected.
Then, the specimen was subjected to analysis by means of
inductively coupled plasma emission analysis (ICP). As a result,
the content of Sn, that of Ni, and that of Co were found to be 61%,
14%, and 25% respectively in terms of the atom number content.
[0410] Separately, using an X-ray diffraction device RINT 2000
(produced by Kabusiki Kaisha RIGAKU), a specimen of the resultant
alloy powder was subjected to wide angle X-ray diffraction analysis
using K.alpha.-rays of Cu as a radiation source, which gave peaks
having a widened half width appeared in a region of
2.theta.=25.degree. to 50.degree.. And there were observed two main
peaks one at 2.theta.=30.6.degree. and another at
2.theta.=43.5.degree. in the X-ray diffraction chart, having a half
width of 0.8.degree. and that of 1.0.degree., respectively. The
presence of these peaks having a wide half width indicates that the
resultant alloy powder is amorphous. Separately, calculation was
carried out on the basis of the half widths and the diffraction
angles of these peaks and in accordance with the foregoing
Scherrer's equation. As a result, there were obtained a crystallite
size of 11 nm and another crystallite size of 9 nm.
[0411] In addition, a specimen of the resultant alloy powder was
subjected to measurement of particle size distribution by means of
a particle size distribution measuring equipment using a laser
scattering method. As a result, it was found to have an average
particle size of 0.35 .mu.m and a particle size distribution of
0.08 to 0.9 .mu.m.
[0412] Further, a specimen of the resultant alloy powder was
examined by means of a scanning electron microscope. As a result,
it was found that an average value-of the [longest length of
particle]/[shortest length of particle] is 1.3. From this result,
the resultant alloy powder was found to comprise spherical
particles.
[0413] Further in addition, a specimen of the resultant alloy
powder was subjected to measurement of specific surface area by
means of a BET method using nitrogen gas. As a result, it was found
to have a specific surface area of 77 m.sup.2/g.
[0414] (2). Preparation of an Electrode Structural Body as an Anode
601:
[0415] 90 parts of the Sn--Ni--Co alloy powder obtained in the
above, 5 parts of a graphite powder as an electrically conductive
auxiliary, 2 parts of polyvinyl alcohol, and 3 parts of
carboxymethylcellulose were mixed to obtain a mixture, and the
mixture was mixed with 100 parts of water as a solvent, and stirred
to obtain a paste-like product. The paste-like product was applied
on a copper foil as a collector, followed by drying, and dried at
150.degree. C. under reduced pressure.
[0416] Thus, there was obtained an electrode structural body as an
anode 601.
EXAMPLE 9
[0417] In this example, there was prepared a rechargeable lithium
battery having such cross-sectional structure as shown in FIG. 6 by
repeating the procedures of Example 1 except that the anode was
prepared using a Sn--In--Ni amorphous alloy material (particulate)
prepared as will be described below.
[0418] The rechargeable lithium battery obtained in this example
was evaluated with respect to its battery characteristics in the
same manner as in Example 1. The evaluated results are shown in
Table 1.
[0419] Preparation of Anode 601:
[0420] (1). Preparation of an Alloy Powder (Particulate) as an
Electrode Material:
[0421] 5.3 parts of a pentahydrate of tin (IV) chloride and 4.5
parts of an indium (III) chloride respectively as the metal
compound capable of being alloyed with lithium, 10.7 parts of a
hexahydrate of nickel (II) chloride as the transition metal
compound, 75.0 parts of a dehydrate of trisodium citrate, 8.8 parts
of ethylenediaminetetraacetic acid and 8.8 parts of potassium
acetate respectively as the complexing agent were mixed with 100
parts of water as the solvent and sufficiently stirred to obtain a
mixed solution. The mixed solution was introduced into the reaction
vessel 201 (provided with the starting material introduction device
202, the reflux device 203, the gas introduction pipe 204, the
agitator 205, and the temperature controlling equipment 206) shown
in FIG. 2 through the starting material introduction device, and in
order to maintain the inside of the reaction vessel in an inert gas
atmosphere, argon gas was introduced into the reaction vessel
through the gas introduction pipe, where excessive argon gas was
exhausted to the outside of the system through the reflux device.
The reaction vessel having the mixed solution therein was heated to
70.degree. C. by means of the temperature controlling equipment
(water bath), and the mixed solution in the reaction vessel was
sufficiently stirred by means of the agitator.
[0422] Here, a specimen of the mixed solution treated in the above
was subjected to analysis by means of a visible-ultraviolet
absorption spectrum analyzer. As a result, as well as in Example 1,
it was found that a complex formed by the metal of the metal
compound (capable of being alloyed with lithium) and the complexing
agent and a complex formed by the transition metal of the
transition metal compound and the, complexing agent are contained
in the mixed solution.
[0423] Then, a solution obtained by dissolving 33.0 parts of a
titanium (III) chloride as the reducing agent in 104.7 parts of
water was heated to 70.degree. C. and added to the mixed solution
in the reaction vessel through the starting material introduction
device, followed by being sufficiently stirred. This adding and
mixing step was performed within one minute. The pH value of the
solution in the reaction vessel was measured. As a result, the
solution was found to have a pH value of 0.05.
[0424] Thereafter, a potassium hydroxide aqueous solution of 8N was
added to the solution in the reaction vessel through the starting
material introduction device while stirring the solution, so that
the pH value of the solution became to be 7.0, and the solution in
the reaction vessel was subjected to a heat treatment at 70.degree.
C. for one hour. The adding and mixing step of the potassium
hydroxide aqueous solution here was performed within one
minute.
[0425] Thereafter, the content in the reaction vessel was taken out
from the vessel, and it was washed with water, and vacuum-dried at
50.degree. C. Thus, there was obtained a product comprising a
Sn--In--Ni alloy power.
[0426] A specimen of the resultant alloy powder was subjected to
analysis by means of X-ray microanalysis (XMA). As a result, Sn, In
and Ni were detected without other elements being detected. Then,
the specimen was subjected to analysis by means of inductively
coupled plasma emission analysis (ICP). As a result, the content of
Sn, that of In, and that of Ni were found to be 65%, 10%, and 25%
respectively in terms of the atom number content.
[0427] Separately, using an X-ray diffraction device RINT 2000
(produced by Kabusiki Kaisha RIGAKU), a specimen of the resultant
alloy powder was subjected to wide angle X-ray diffraction analysis
using K.alpha.-rays of Cu as a radiation source, which gave peaks
having a widened half width appeared in a region of
2.theta.=25.degree. to 50.degree.. And there were observed two main
peaks one at 2.theta.=30.7.degree. and another at
2.theta.=43.7.degree. in the X-ray diffraction chart, having a half
width of 0.8.degree. and that of 0.8.degree., respectively. The
presence of these peaks having a wide half width indicates that the
resultant alloy powder is amorphous. Separately, calculation was
carried out on the basis of the half widths and the diffraction
angles of these peaks and in accordance with the foregoing
Scherrer's equation. As a result, there were obtained a crystallite
size of 11 nm and another crystallite size of 11 nm.
[0428] In addition, a specimen of the resultant alloy powder was
subjected to measurement of particle size distribution by means of
a particle size distribution measuring equipment using a laser
scattering method. As a result, it was found to have an average
particle size of 0.31 .mu.m and a particle size distribution of
0.08 to 1.0 .mu.m.
[0429] Further, a specimen of the resultant alloy powder was
examined by means of a scanning electron microscope. As a result,
it was found that an average value of the [longest length of
particle]/[shortest length of particle] is 1.4. From this result,
the resultant alloy powder was found to comprise spherical
particles.
[0430] Further in addition, a specimen of the resultant alloy
powder was subjected to measurement of specific surface area by
means of a BET method using nitrogen gas. As a result, it was found
to have a specific surface area of 62 m.sup.2/g.
[0431] (2). Preparation of an Electrode Structural Body as an Anode
601:
[0432] 90 parts of the Sn--In--Ni alloy powder obtained in the
above, 5 parts of a graphite powder as an electrically conductive
auxiliary, 2 parts of polyvinyl alcohol, and 3 parts of
carboxymethylcellulose were mixed to obtain a mixture, and the
mixture was mixed with 100 parts of water as a solvent, and stirred
to obtain a paste-like product. The paste-like product was applied
on a copper foil as a collector, followed by drying, and dried at
150.degree. C. under reduced pressure.
[0433] Thus, there was obtained an electrode structural body as an
anode 601.
EXAMPLE 10
[0434] In this example, there was prepared a rechargeable lithium
battery having such cross-sectional structure as shown in FIG. 6 by
repeating the procedures of Example 1 except that the anode was
prepared using a Zn--Ni amorphous alloy material (particulate)
prepared as will be described below.
[0435] The rechargeable lithium battery obtained in this example
was evaluated with respect to its battery characteristics in the
same manner as in Example 1. The evaluated results are shown in
Table 1.
[0436] Preparation of Anode 601:
[0437] (1). Preparation of an Alloy Powder (Particulate) as an
Electrode Material:
[0438] 6.1 parts of a zinc (II) chloride as the metal compound
capable of being alloyed with lithium, 10.7 parts of a hexahydrate
of nickel (II) chloride as the transition metal compound, 40.0
parts of a dihydrate of trisodium citrate and 4.2 parts of a
disodium ethylenediaminetetraacete respectively as the complexing
agent were mixed with 100 parts of water as the solvent and
sufficiently stirred to obtain a mixed solution. The mixed solution
was introduced into the reaction vessel 201 (provided with the
starting material introduction device 202, the reflux device 203,
the gas introduction pipe 204, the agitator 205, and the
temperature controlling equipment 206) shown in FIG. 2 through the
starting material introduction device, and in order to maintain the
inside of the reaction vessel in an inert gas atmosphere, argon gas
was introduced into the reaction vessel through the gas
introduction pipe, where excessive argon gas was exhausted to the
outside of the system through the reflux device. The reaction
vessel having the mixed solution therein was heated to 70.degree.
C. by means of the temperature controlling equipment (water bath),
and the mixed solution in the reaction vessel was sufficiently
stirred by means of the agitator.
[0439] Here, a specimen of the mixed solution treated in the above
was subjected to analysis by means of a visible-ultraviolet
absorption spectrum analyzer. As a result, as well as in Example 1,
it was found that a complex formed by the metal of the metal
compound (capable of being alloyed with lithium) and the complexing
agent and a complex formed by the transition metal of the
transition metal compound and the complexing agent are contained in
the mixed solution.
[0440] Then, a solution obtained by dissolving 25.0 parts of a
sodium hypophosphite as the reducing agent in 75 parts of water was
heated to 70.degree. C. and added to the mixed solution in the
reaction vessel through the starting material introduction device,
followed by being sufficiently stirred for one hour while
maintaining the temperature of the solution at 70.degree. C This
adding and mixing step was performed within one minute. The pH
value of the content in the reaction vessel was measured. As a
result, it was found to have a pH value of 6.5.
[0441] Thereafter, the content in the reaction vessel was taken out
from the vessel, and it was washed with water, and vacuum-dried at
50.degree. C. Thus, there was obtained a product comprising a
Zn--Ni alloy power.
[0442] A specimen of the resultant alloy powder was subjected to
analysis by means of X-ray microanalysis (XMA). As a result, Zn, Ni
and P were detected without other elements being detected. Then,
the specimen was subjected to analysis by means of inductively
coupled plasma emission analysis (ICP). As a result, the content of
Zn, that of Ni, and that of P were found to be 73%, 23%, and 4%
respectively in terms of the atom number content.
[0443] Separately, using an X-ray diffraction device RINT 2000
(produced by Kabusiki Kaisha RIGAKU), a specimen of the resultant
alloy powder was subjected to wide angle X-ray diffraction analysis
using K.alpha.-rays of Cu as a radiation source. As a result, there
was observed a main peak at 2.theta.=43.2.degree. in the X-ray
diffraction chart, having a half width of 0.5.degree.. The presence
of this peak having such wide half width indicates that the
resultant alloy powder is amorphous. Separately, calculation was
carried out on the basis of the half width and the diffraction
angle of the peak and in accordance with the foregoing Scherrer's
equation. As a result, there were obtained a crystallite size of 18
nm.
[0444] In addition, a specimen of the resultant alloy powder was
subjected to measurement of particle size distribution by means of
a particle size distribution measuring equipment using a laser
scattering method. As a result, it was found to have an average
particle size of 0.9 .mu.m and a particle size distribution of 0.20
to 16.5 .mu.m.
[0445] Further, a specimen of the resultant alloy powder was
examined by means of a scanning electron microscope. As a result,
it was found that an average value of the [longest length of
particle]/[shortest length of particle] is 1.7. From this result,
the resultant alloy powder was found to comprise spherical
particles.
[0446] Further in addition, a specimen of the resultant alloy
powder was subjected to measurement of specific surface area by
means of a BET method using nitrogen gas. As a result, it was found
to have a specific surface area of 17 m.sup.2/g.
[0447] (2). Preparation of an Electrode Structural Body as an Anode
601:
[0448] 90 parts of the Zn--Ni alloy powder obtained in the above, 5
parts of an acetylene black powder as an electrically conductive
auxiliary, and 5 parts of a polyvinylidene fluoride powder were
mixed to obtain a mixture, and the mixture was mixed with 100 parts
of N-methyl-2-pyrrolidone as a solvent, and stirred to obtain a
paste-like product. The paste-like product was applied on a copper
foil as a collector, followed by drying, and dried at 150.degree.
C. under reduced pressure.
[0449] Thus, there was obtained an electrode structural body as an
anode 601.
EXAMPLE 11
[0450] In this example, there was prepared a rechargeable lithium
battery having such cross-sectional structure as shown in FIG. 6 by
repeating the procedures of Example 1 except that the anode was
prepared using an In--Ni amorphous alloy material (particulate)
prepared as will be described below.
[0451] The rechargeable lithium battery obtained in this example
was evaluated with respect to its battery characteristics in the
same manner as in Example 1. The evaluated results are shown in
Table 1.
[0452] Preparation of Anode 601:
[0453] (1). Preparation of an Alloy Powder (Particulate) as an
Electrode Material:
[0454] 4.5 parts of an indium (III) chloride as the metal compound
capable of being alloyed with lithium, 10.7 parts of a hexahydrate
of nickel (II) chloride as the transition metal compound, 40.0
parts of a dihydrate of trisodium citrate and 4.2 parts of a
disodium ethylenediaminetetraacete respectively as the complexing
agent were mixed with 100 parts of water as the solvent and
sufficiently stirred to obtain a mixed solution. The mixed solution
was introduced into the reaction vessel 201 (provided with the
starting material introduction device 202, the reflux device 203,
the gas introduction pipe 204, the agitator 205, and the
temperature controlling equipment 206) shown in FIG. 2 through the
starting material introduction device, and in order to maintain the
inside of the reaction vessel in an inert gas atmosphere, argon gas
was introduced into the reaction vessel through the gas
introduction pipe, where excessive argon gas was exhausted to the
outside of the system through the ref lux device. The reaction
vessel having the mixed solution therein was heated to 70.degree.
C. by means of the temperature controlling equipment (water bath),
and the mixed solution in the reaction vessel was sufficiently
stirred by means of the agitator.
[0455] Here, a specimen of the mixed solution treated in the above
was subjected to analysis by means of a visible-ultraviolet
absorption spectrum analyzer. As a result, as well as in Example 1,
it was found that a complex formed by the metal of the metal
compound (capable of being alloyed with lithium) and the complexing
agent and a complex formed by the transition metal of the
transition metal compound and the complexing agent are contained in
the mixed solution.
[0456] Then, a solution obtained by dissolving 7.5. parts of a
sodium thiosulfate as the reducing agent in 25 parts of water was
heated to 70.degree. C. and added to the mixed solution in the
reaction vessel through the starting material introduction device,
followed by being sufficiently stirred for one hour while
maintaining the temperature of the solution at 70.degree. C. This
adding and mixing step was performed within one minute. The pH
value of the content in the reaction vessel was measured. As a
result, it was found to have a pH value of 6.5.
[0457] Thereafter, the content in the reaction vessel was taken out
from the vessel, and it was washed with water, and vacuum-dried at
50.degree. C. Thus, there was obtained a product comprising an
In--Ni alloy power.
[0458] A specimen of the resultant alloy powder was subjected to
analysis by, means of X-ray microanalysis (XMA). As a result, In,
Ni and S were detected without other elements being detected. Then,
the specimen was subjected to analysis by means of inductively
coupled plasma emission analysis (ICP). As a result, the content of
In, that of Ni, and that of S were found to be 48%, 44%, and 8%
respectively in terms of the atom number content.
[0459] Separately, using an X-ray diffraction device RINT 2000
(produced by Kabusiki Kaisha RIGAKU), a specimen of the resultant
alloy powder was subjected to wide angle X-ray diffraction analysis
using K.alpha.-rays of Cu as a radiation source. As a result, there
were observed two main peaks one at 2.theta.=32.8.degree. and the
other at 2.theta.=43.5.degree. and in the X-ray diffraction chart,
respectively having a half width of 0.5.degree. and a half width of
0.6.degree.. The presence of these peaks having such wide half
width indicates that the resultant alloy powder is amorphous.
Separately, calculation was carried out on the basis of the half
width and the diffraction angle of the peak and in accordance with
the foregoing Scherrer's equation. As a result, there were obtained
a crystallite size of 17 nm and another crystallite size of 15
nm.
[0460] In addition, a specimen of the resultant alloy powder was
subjected to measurement of particle size distribution by means of
a particle size distribution measuring equipment using a laser
scattering method. As a result, it was found to have an average
particle size of 0.8 .mu.m and a particle size distribution of 0.18
to 14.2 .mu.m.
[0461] Further, a specimen of the resultant alloy powder was
examined by means of a scanning electron microscope. As a result,
it was found that an average value of the. [longest length of
particle]/[shortest length of particle] is 1.5. From this result,
the resultant alloy powder was found to comprise spherical
particles.
[0462] Further in addition, a specimen of the resultant alloy
powder was subjected to measurement of specific surface area by
means of a BET method using nitrogen gas. As a result, it was found
to have a specific surface area of 26 m.sup.2/g.
[0463] (2). Preparation of an Electrode Structural Body as an Anode
601:
[0464] 90 parts of the In--Ni alloy powder obtained in the above, 5
parts of an acetylene black powder as an electrically conductive
auxiliary, and 5 parts of a polyvinylidene fluoride powder were
mixed to obtain a mixture, and the mixture was mixed with 100 parts
of N-methyl-2-pyrrolidone as a solvent, and stirred to obtain a
paste-like product. The paste-like product was applied on a copper
foil as a collector, followed by drying, and dried at 150.degree.
C. under reduced pressure.
[0465] Thus, there was obtained an electrode structural body as an
anode 601.
EXAMPLE 12
[0466] In this example, there was prepared a rechargeable lithium
battery having such cross-sectional structure as shown in FIG. 6 by
repeating the procedures of Example 1 except that the anode was
prepared using a Sn--Ni amorphous alloy material (particulate)
prepared using the fabrication apparatus shown in FIG. 3 as will be
described below. As previously described, the fabrication apparatus
shown in FIG. 3 comprises the starting material addition vessel
302, the reducing agent addition vessel 303, the mixing vessel 304,
the addition vessel 308, the reaction vessel 301, and the product
recovery vessel 309.
[0467] The rechargeable lithium battery obtained in this example
was evaluated with respect to its battery characteristics in the
same manner as in Example 1. The evaluated results are shown in
Table 1.
[0468] Preparation of Anode 601:
[0469] (1). Preparation of an Alloy Powder (Particulate) as an
Electrode Material:
[0470] 53 parts of a pentahydrate of tin (IV) chloride as the metal
compound capable of being alloyed with lithium, 107 parts of a
hexahydrate of nickel (II) chloride as the transition metal
compound, 750 parts of a dihydrate of trisodium citrate, 88 parts
of ethylenediaminetetraacetic acid and 88 parts of a potassium
acetate respectively as the complexing agent were mixed with 914
parts of water as the solvent and sufficiently stirred to obtain a
mixed solution. The mixed solution was introduced into the starting
material addition vessel 302 (charged with nitrogen gas) of the
fabrication apparatus shown in FIG. 3, where the mixed solution was
well stirred by means of the agitator and it was heated to and
maintained at 70.degree. C. by means of the temperature controlling
equipment.
[0471] Here, a specimen of the mixed solution treated in the above
was subjected to analysis by means of a visible-ultraviolet
absorption spectrum analyzer. As a result, as well as in Example 1,
it was found that a complex formed by the metal of the metal
compound (capable of being alloyed with lithium) and the complexing
agent and a complex formed by the transition metal of the
transition metal compound and the complexing agent are contained in
the mixed solution.
[0472] Separately, a mixture comprising 231 parts of a titanium
(III) chloride as the reducing agent and 769 parts of water was
introduced into the reducing agent addition vessel 303 charged with
nitrogen gas, where the mixture was well stirred by means of the
agitator and heated to and maintained at 70.degree. C. by means of
the temperature controlling equipment.
[0473] Further, a potassium hydroxide aqueous solution of 8N was
introduced into the addition vessel 308, where it was heated to and
maintained at 70.degree. C. by means of the temperature controlling
equipment.
[0474] Then, the flow rate regulating valve of each of the starting
material addition vessel 302, the reducing agent addition vessel
303, the mixing vessel 304, the reaction vessel 301, and the
addition vessel 308 was opened while regulating the opening of the
valve.
[0475] That is, the flow rate regulating valve of the starting
material addition vessel 302 was opened to flow the mixed solution
in the starting material addition vessel into the mixing vessel 304
at a prescribed flow rate by regulating the opening of the flow
rate regulating valve and the flow rate regulating valve of the
reducing agent addition vessel 303 was opened to flow the reducing
agent solution in the reducing agent addition vessel into the
mixing vessel 304 at a prescribed flow rate by regulating the
opening of the flow rate regulating valve, where a mixture
comprising the mixed solution and the reducing agent solution
introduced into the mixing vessel was well stirred by stirring by
means of the agitator while adjusting the temperature of the
mixture to 70.degree. C. by means of the temperature controlling
equipment.
[0476] The flow rate regulating valve of the mixing vessel 304 was
opened to flow the solution obtained in the mixing vessel into the
reaction vessel 301 at a prescribed flow rate by regulating the
opening of the flow rate regulating valve and the flow rate
regulating valve of the addition vessel 308 was opened to flow the
potassium hydroxide aqueous solution in the addition vessel into
the reaction vessel 301 at a prescribed flow rate by regulating the
opening of the flow rate regulating valve, where the solution
introduced into the reaction vessel and which was added with the
potassium hydroxide aqueous solution was stirred by mean of the
agitator while adjusting the temperature of the solution to
70.degree. C. by means of the temperature controlling
equipment.
[0477] The flow rate regulating valve of the reaction vessel 301
was opened to flow a product obtained in there action vessel into
the product recovery vessel at a prescribed flow rate by regulating
the opening of the flow rate regulating valve, where the
temperature of the product recovery vessel was adjusted to
70.degree. C. by means of the temperature controlling
equipment.
[0478] In the above, the flow rate of the flow rate regulating
valve of the starting material addition vessel 302, that of the
reducing agent addition vessel 303, that of the addition vessel
308, that of the mixing vessel 304, and that of the reaction vessel
301 were adjusted so that they became 2:1:1.5:3:4.5 and that the
solution stayed in the reaction vessel for 5 minutes; that is, the
solution took 5 minutes to pass through the reaction vessel.
[0479] In the above, the pH value of the solution in the mixing
vessel 304 was examined, and as a result, the solution was found to
have a pH value of 0.1. Similarly, the pH value of the solution in
the reaction vessel 301, as a result, the solution was found to
have a pH value of 7.4.
[0480] Thereafter, the product in the product recovery vessel 309
was taken out, and it was washed with water, and vacuum-dried at
50.degree. C. Thus, there was obtained a Sn--Ni alloy power.
[0481] A specimen of the resultant alloy powder was subjected to
analysis by means of X-ray microanalysis (XMA). As a result, only
Sn and Ni were detected without other elements being detected.
Then, the specimen was subjected to analysis by means of
inductively coupled plasma emission analysis (ICP). As a result,
the content of Sn and that of Ni were found to be 63% and 37%
respectively in terms of the atom number content.
[0482] Separately, using an X-ray diffraction device RINT 2000
(produced by Kabusiki Kaisha RIGAKU), a specimen of the resultant
alloy powder was subjected to wide angle X-ray diffraction analysis
using K.alpha.-rays of Cu as a radiation source, which gave peaks
having a widened half width appeared in a region of
2.theta.=25.degree. to 50.degree.. And there were observed two main
peaks one at 2.theta.=30.9.degree. and another at
2.theta.=43.8.degree. in the X-ray diffraction chart, having a half
width of 0.7.degree. and that of 0.7.degree., respectively. The
presence of these peaks having a wide half width indicates that the
resultant alloy powder is amorphous. Separately, calculation was
carried out on the basis of the half widths and the diffraction
angles of these peaks and in accordance with the foregoing
Scherrer's equation. As a result, there were obtained a crystallite
size of 12 nm and another crystallite size of 13 nm.
[0483] In addition, a specimen of the resultant alloy powder was
subjected to measurement of particle size distribution by means of
a particle size distribution measuring equipment using a laser
scattering method. As a result, it was found to have an average
particle size of 0.24 .mu.m and a particle size distribution of
0.05 to 0.75 .mu.m.
[0484] Further, a specimen of the resultant alloy powder was
examined by means of a scanning electron microscope. As a result,
it was found that an average value of the [longest length of
particle]/[shortest length of particle] is 1.2. From this result,
the resultant alloy powder was found to comprise spherical
particles.
[0485] Further in addition, a specimen of the resultant alloy
powder was subjected to measurement of specific surface area by
means of a BET method using nitrogen gas. As a result, it was found
to have a specific surface area of 78 m.sup.2/g.
[0486] (2). Preparation of an Electrode Structural Body as an Anode
601:
[0487] 90 parts of the Sn--Ni alloy powder obtained in the above, 5
parts of a graphite powder as an electrically conductive auxiliary,
2 parts of polyvinyl alcohol, and 3 parts of carboxymethylcellulose
were mixed to obtain a mixture, and the mixture was mixed with 100
parts of water as a solvent, and stirred to obtain a paste-like
product. The paste-like product was applied on a copper foil as a
collector, followed by drying, and dried at 150.degree. C. under
reduced pressure.
[0488] Thus, there was obtained an electrode structural body as an
anode 601.
COMPARATIVE EXAMPLE 1
[0489] In this comparative example, there was prepared a
rechargeable lithium battery having such cross-sectional structure
as shown in FIG. 6 by repeating the procedures of Example 1 except
that the anode was prepared using a Sn-powder prepared as will be
described below.
[0490] The rechargeable lithium battery obtained in this
comparative example was evaluated with respect to its battery
characteristics in the same manner as in Example 1. The evaluated
results are shown in Table 1.
[0491] Preparation of Anode 601:
[0492] (1). Preparation of a Sn-Powder an Electrode Material:
[0493] 21.0 parts of a pentahydrate of tin (IV) chloride, 75.0
parts of a dihydrate of trisodium citrate, 8.8 parts of
ethylenediaminetetraacetic acid, and 8.8 parts of a potassium
acetate were mixed with 100 parts of water and sufficiently stirred
to obtain a mixed solution. The mixed solution was introduced into
the reaction vessel 201 (provided with the starting material
introduction device 202, the reflux device 203, the gas
introduction pipe 204, the agitator 205, and the temperature
controlling equipment 206) shown in FIG. 2 through the starting
material introduction device, and in order to maintain the inside
of the reaction vessel in a nitrogen gas atmosphere, nitrogen gas
was introduced into the reaction vessel through the gas
introduction pipe, where excessive nitrogen gas was exhausted to
the outside of the system through the reflux device. The reaction
vessel having the mixed solution therein was heated to 70.degree.
C. by means of the temperature controlling equipment (water bath),
and the mixed solution in the reaction vessel was sufficiently
stirred by means of the agitator.
[0494] Then, a solution obtained by dissolving 23.1 parts of a
titanium (III) chloride in 73.3 parts of water was heated to
70.degree. C. and added to the mixed solution in the reaction
vessel through the starting material introduction device, followed
by being sufficiently stirred. This adding and mixing step was
performed within one minute. The pH value of the content in the
reaction vessel was measured. As a result, it was found to have a
pH value of 0.1.
[0495] Thereafter, a potassium hydroxide aqueous solution of 8N was
added to the content in the reaction vessel through the starting
material introduction device while stirring the solution, so that
the pH value of the content became to be 7.0, and the content in
the reaction vessel was subjected to a heat treatment at 70.degree.
C. for 30 minutes. The adding and mixing step of the potassium
hydroxide aqueous solution here was performed within one
minute.
[0496] Thereafter, the content in the reaction vessel was taken out
from the vessel, and it was washed with water, and vacuum-dried at
50.degree. C. Thus, there was obtained a Sn-power.
[0497] A specimen of the result powder was subjected to analysis by
means of X-ray microanalysis (XMA). As a result, only Sn was
detected without other elements being detected. Separately, using
an X-ray diffraction device RINT 2000 (produced by Kabusiki Kaisha
RIGAKU), a specimen of the resultant powder was subjected to wide
angle X-ray diffraction analysis using K.alpha.-rays of Cu as a
radiation source, and calculation was carried out on the basis of
the half width and the diffraction angle in the X-ray diffraction
analysis and in accordance with the foregoing Scherrer's equation.
As a result, there was obtained a crystallite size of 52 nm.
[0498] (2). Preparation of an Electrode Structural Body as an Anode
601:
[0499] 90 parts of the Sn-powder obtained in the above, 5 parts of
an acetylene black powder as an electrically conductive auxiliary,
2 parts of polyvinyl alcohol, and 3 parts of carboxymethylcellulose
were mixed to obtain a mixture, and the mixture was mixed with 100
parts of water as a solvent, and stirred to obtain a paste-like
product. The paste-like product was applied on a copper foil as a
collector, followed by drying, and dried at 150.degree. C. under
reduced pressure.
[0500] Thus, there was obtained an electrode structural body as an
anode 601.
COMPARATIVE EXAMPLE 2
[0501] In this comparative example, there was prepared a
rechargeable lithium battery having such cross-sectional structure
as shown in FIG. 6 by repeating the procedures of Example 1 except
that the anode was prepared using a Sn--Ni amorphous alloy material
(particulate) prepared as will be described below.
[0502] The rechargeable lithium battery obtained in this
comparative example was evaluated with respect to its battery
characteristics in the same manner as in Example 1. The evaluated
results are shown in Table 1.
[0503] Preparation of Anode 601:
[0504] (1). Preparation of an Alloy Powder as an Electrode
Material:
[0505] 5.3 parts of a pentahydrate of tin (IV) chloride and 10.7
parts of a hexahydrate of nickel (II) chloride were mixed with 100
parts of water and sufficiently stirred to obtain a mixed solution.
The mixed solution was introduced into the reaction vessel 201
(provided with the starting material introduction device 202, the
reflux device 203, the gas introduction pipe 204, the agitator 205,
and the temperature controlling equipment 206) shown in FIG. 2
through the starting material introduction device, and in order to
maintain the inside of the reaction vessel in a nitrogen gas
atmosphere, nitrogen gas was introduced into the reaction vessel
through the gas introduction pipe, where excessive argon gas was
exhausted to the outside of the system through the reflux device.
The reaction vessel having the mixed solution therein was heated to
70.degree. C. by means of the temperature controlling equipment
(water bath), and the mixed solution in the reaction vessel was
sufficiently stirred by means of the agitator.
[0506] Then, a solution obtained by dissolving 23.1 parts of a
titanium (III) chloride in 73.3 parts of water was heated to
70.degree. C. and added to the mixed solution in the reaction
vessel through the starting material introduction device, followed
by being sufficiently stirred. This adding and mixing step was
performed within one minute. The pH value of the solution in the
reaction vessel was measured. As a result, it was found to have a
pH value of 0.1.
[0507] Thereafter, a potassium hydroxide aqueous solution of 8N was
added to the solution in the reaction vessel through the starting
material introduction device while stirring the solution, so that
the pH value of the solution became to be 8.0, and the solution in
the reaction vessel was subjected to a heat treatment at 70.degree.
C. for 30 minutes. The adding and mixing step of the potassium
hydroxide aqueous solution here was performed within one
minute.
[0508] Thereafter, the content in the reaction vessel was taken
out, and it was washed with water, and vacuum-dried at 50.degree.
C. Thus, there was obtained a Sn--Ni alloy power.
[0509] A specimen of the resultant alloy powder was subjected to
analysis by means of X-ray microanalysis (XMA). As a result, Sn,
Ni, and O were detected without other elements being detected.
Then, the specimen was subjected to analysis by means of
inductively coupled plasma emission analysis (ICP). As a result,
the content of Sn, that of Ni, and that of O were found to be 30%,
5%, and 65% respectively in terms of the atom number content.
[0510] Separately, a specimen of the resultant alloy powder was
subjected to qualitative analysis using an X-ray diffraction
apparatus. The result revealed that the alloy powder is mostly
comprised of thin oxide.
[0511] Further, using an X-ray diffraction device RINT 2000
(produced by Kabusiki Kaisha RIGAKU), a specimen of the resultant
alloy powder was subjected to wide angle X-ray diffraction analysis
using K.alpha.-rays of Cu as a radiation source. As a result, there
were observed two main peaks one at 2.theta.=26.7.degree. and
another at.2.theta.=51.9.degree. in the X-ray diffraction chart,
having a half width of 0.3.degree. and that of 0.4.degree.,
respectively. Separately, calculation was carried out on the basis
of the half widths and the diffraction angles of these peaks and in
accordance with the foregoing Scherrer's equation. As a result,
there were obtained a crystallite size of 28 nm and another
crystallite size of 23 nm.
[0512] (2). Preparation of an Electrode Structural Body as an Anode
601:
[0513] 90 parts of the alloy powder obtained in the above, 5 parts
of an acetylene black powder as an electrically conductive
auxiliary, 2 parts of polyvinyl alcohol, and 3 parts of
carboxymethylcellulose were mixed to obtain a mixture, and the
mixture was mixed with 100 parts of water as a solvent, and stirred
to obtain a paste-like product. The paste-like product was applied
on a copper foil as a collector, followed by drying, and dried at
150.degree. C. under reduced pressure.
[0514] Thus, there was obtained an electrode structural body as an
anode 601.
COMPARATIVE EXAMPLE 3
[0515] In this comparative example, there was prepared a
rechargeable lithium battery having such cross-sectional structure
as shown in FIG. 6 by repeating the procedures of Example 1 except
that the anode was prepared as will be described below.
[0516] The rechargeable lithium battery obtained in this
comparative example was evaluated with respect to its battery
characteristics in the same manner as in Example 1. The evaluated
results are shown in Table 1.
[0517] Preparation of an Anode 601:
[0518] There were provided a cathode comprising a copper foil
having a thickness of 18 m which has been degreased and washed
using acetone and isopropyl alcohol and dried and an node
comprising a tin plate which has been degreased and washed using
acetone and isopropyl alcohol and dried.
[0519] The cathode and the anode was arranged in an electrolyte
solution comprising 40 g/liter of a stannous sulfate, 60 g/liter of
sulfuric acid, 2 g/liter of a gelatin, and water as a solvent so as
to have an interval between the cathode and the anode, where the
electrolyte solution was maintained at 25.degree. C., while
stirring the electrolyte solution, a direct current electric field
was applied between the cathode and the anode to make the cathode
have an electric current density of 10 mA/cm.sup.2, and under this
condition, energization of 20 C/cm.sup.2 was conducted, whereby a
layer comprising a metallic tin material was formed on the copper
foil as the cathode.
[0520] After the copper foil having the metallic tin material layer
was washed with water, it was treated by immersing in an aqueous
solution containing 60 g/liter of Na.sub.3PO.sub.4.12H.sub.2O
dissolved therein maintained at 60.degree. C. for one minute, and
the copper foil thus treated was washed with water and dried at
150.degree. C. under reduced pressure. Thus, there was obtained an
anode 601.
[0521] Using an X-ray diffraction device RINT 2000 (produced by
Kabusiki Kaisha RIGAKU), a specimen of the electrode material layer
of the anode 601 was subjected to wide angle X-ray diffraction
analysis using K.alpha.-rays of Cu as a radiation source, and
calculation was carried out on the basis of the half width and the
diffraction angle in the X-ray diffraction chart and in accordance
with the foregoing Scherrer's equation. As a result, there was
obtained a crystallite size of 57 nm.
COMPARATIVE EXAMPLE 4
[0522] In this comparative example, there was prepared a
rechargeable lithium battery having such cross-sectional structure
as shown in FIG. 6 by repeating the procedures of Example 1 except
that the anode was prepared as will be described below.
[0523] The rechargeable lithium battery obtained in this
comparative example was evaluated with respect to its battery
characteristics in the same manner as in Example 1. The evaluated
results are shown in Table 1.
[0524] Preparation of an Anode 601:
[0525] 90 parts of a commercially available Sn-powder, 5 parts of
an acetylene black powder as an electrically conductive auxiliary,
and 5 parts of a polyvinylidene fluoride powder were mixed to
obtain a mixture, and the mixture was mixed with 100 parts of
N-methyl-2-pyrrolidone as a solvent, and stirred to obtain a
paste-like product. The paste-like product was applied on a copper
foil as a collector, followed by drying, and dried at 150.degree.
C. under reduced pressure. Thus, there was obtained an anode
601.
[0526] Now, Using an X-ray diffraction device RINT 2000 (produced
by Kabusiki Kaisha RIGAKU), a specimen of aforesaid commercially
available Sn-powder was subjected to wide angle X-ray diffraction
analysis using K .alpha.-rays of Cu as a radiation source, and
calculation was carried out on the basis of the half width and the
diffraction angle in the X-ray diffraction chart and in accordance
with the foregoing Scherrer's equation. As a result, there was
obtained a crystallite size of 80 nm.
COMPARATIVE EXAMPLE 5
[0527] In this comparative example, there was prepared a
rechargeable lithium battery having such cross-sectional structure
as shown in FIG. 6 by repeating the procedures of Example 1 except
that the anode was prepared using a Zn-powder prepared as will be
described below.
[0528] The rechargeable lithium battery obtained in this
comparative example was evaluated with respect to its battery
characteristics in the same manner as in Example 1. The evaluated
results are shown in Table 1.
[0529] Preparation of Anode 601:
[0530] (1). Preparation of a Zn-Powder as an Electrode
Material:
[0531] 6.1 parts of a zinc (II) chloride, 40 parts of a dihydrate
of trisodium citrate, and 4.2 parts of ethylenediaminetetraacetic
acid were mixed with 100 parts of water and sufficiently stirred to
obtain a mixed solution. The mixed solution was introduced into the
reaction vessel 201 (provided with the starting material
introduction device 202, the reflux device 203, the gas
introduction pipe 204, the agitator 205, and the temperature
controlling equipment 206) shown in FIG. 2 through the starting
material introduction device, and in order to maintain the inside
of the reaction vessel in an inert gas atmosphere, argon gas was
introduced into the reaction vessel through the gas introduction
pipe, where excessive argon gas was exhausted to the outside of the
system through the reflux device. The reaction vessel having the
mixed solution therein was heated to 70.degree. C. by means of the
temperature controlling equipment (water bath), and the mixed
solution in the reaction vessel was sufficiently stirred by means
of the agitator.
[0532] Then, a solution obtained by dissolving 25.0 parts of a
sodium hypophosphite as a reducing agent in 75 parts of water was
heated to 70.degree. C. and added to the mixed solution in the
reaction vessel through the starting material introduction device
while stirring the mixed solution, followed by subjecting to a heat
treatment at 70.degree. C. for one hour. This adding and mixing
step was performed within one minute. The pH value of the content
in the reaction vessel was measured. As a result, it was found to
have a pH value of 6.5.
[0533] Thereafter, the content in the reaction vessel was taken
out, and it was washed with water, and vacuum-dried at 50.degree.
C. Thus, there was obtained a Zn-power.
[0534] A specimen of the resultant powder was subjected to analysis
by means of X-ray microanalysis (XMA). As a result, only Zn was
detected without other elements being detected. Then, using an
X-ray diffraction device RINT 2000 (produced by Kabusiki Kaisha
RIGAKU), a specimen of the resultant powder was subjected to wide
angle X-ray diffraction analysis using K.alpha.-rays of Cu as a
radiation source, and calculation was carried out on the basis of
the half width and the diffraction angle in the X-ray diffraction
chart and in accordance with the foregoing Scherrer's equation. As
a result, there was obtained a crystallite size of 51 nm.
[0535] (2). Preparation of an Electrode Structural Body as an Anode
601:
[0536] 90 parts of the Zn-powder obtained in the above, 5 parts of
an acetylene black powder as an electrically conductive auxiliary,
and 5 parts of a polyvinylidene fluoride powder were mixed to
obtain a mixture, and the mixture was mixed with 100 parts of
N-methyl-2-pyrrolidone as a solvent, and stirred to obtain a
paste-like product. The paste-like product was applied on a copper
foil as a collector, followed by drying, and dried at 150.degree.
C. under reduced pressure.
[0537] Thus, there was obtained an electrode structural body as an
anode 601.
COMPARATIVE EXAMPLE 6
[0538] In this comparative example, there was prepared a
rechargeable lithium battery having such cross-sectional structure
as shown in FIG. 6 by repeating the procedures of Example 1 except
that the anode was prepared using a In-powder prepared as will be
described below.
[0539] The rechargeable lithium battery obtained in this
comparative example was evaluated with respect to its battery
characteristics in the same manner as in Example 1. The evaluated
results are shown in Table 1.
[0540] Preparation of Anode 601:
[0541] (1). Preparation of an In-Powder as an Electrode
Material:
[0542] 4.5 parts of a indium (III) chloride, 40.0 parts of a
dihydrate of trisodium citrate and 4.2 parts of a disodium
ethylenediaminetetraacete were mixed with 100 parts of water and
sufficiently stirred to obtain a mixed solution. The mixed solution
was introduced into the reaction vessel 201 (provided with the
starting material introduction device 202, the reflux device 203,
the gas introduction pipe 204, the agitator 205, and the
temperature controlling equipment 206) shown in FIG. 2 through the
starting material introduction device, and in order to maintain the
inside of the reaction vessel in an inert gas atmosphere, argon gas
was introduced into the reaction vessel through the gas
introduction pipe, where excessive argon gas was exhausted to the
outside of the system through the reflux device. The reaction
vessel having the mixed solution therein was heated to 70.degree.
C. by means of the temperature controlling equipment (water bath),
and the mixed solution in the reaction vessel was sufficiently
stirred by means of the agitator.
[0543] Then, a solution obtained by dissolving 7.5 parts of a
sodium hypophosphite as a reducing agentin 25 parts of water was
heated to 70.degree. C. and added to the content in the reaction
vessel through the starting material introduction device while
stirring the content, followed by subjecting a heat treatment at
70.degree. C. for one hour. This adding and mixing step was
performed within one minute. The pH value of the content in the
reaction vessel was measured. As a result, it was found to have a
pH value of 6.5.
[0544] Thereafter, the content in the reaction vessel was taken
out, and it was washed with water, and vacuum-dried at 50.degree.
C. Thus, there was obtained an In-power.
[0545] A specimen of the resultant powder was subjected to analysis
by means of X-ray microanalysis (XMA). As a result, only In was
detected without other elements being detected. Then, using an
X-ray diffraction device RINT 2000 (produced by Kabusiki Kaisha
RIGAKU), a specimen of the-resultant powder was subjected to wide
angle X-ray diffraction analysis using K.alpha.-rays of Cu as a
radiation source, and calculation was carried out on the basis of
the half width and the diffraction angle in the X-ray diffraction
chart and in accordance with the foregoing Scherrer's equation. As
a result, there was obtained a crystallite size of 53 nm.
[0546] (2). Preparation of an Electrode Structural Body as an Anode
601:
[0547] 90 parts of the In-powder obtained in the above, 5 parts of
an acetylene black powder as an electrically conductive auxiliary,
and 5 parts of a polyvinylidene fluoride powder were mixed to
obtain a mixture, and the mixture was mixed with 100 parts of
N-methyl-2-pyrrolidone as a solvent, and stirred to obtain a
paste-like product. The paste-like product was applied on a copper
foil as a collector, followed by drying, and dried at 150.degree.
C. under reduced pressure.
[0548] Thus, there was obtained an electrode structural body as an
anode 601.
[0549] Table 1 illustrates the evaluated battery characteristics of
the rechargeable lithium batteries obtained in Examples 1-12 and
Comparative Examples 1-6. In Table 1, the values of Examples 2-9
and 12 and those of Comparative Examples 1-4 are normalized values
when the values of Example 1 are set at 100. Similarly, the values
of Comparative Example 5 are normalized values when the values of
Example 10 are set at 100, and the values of Comparative Example 6
are normalized values when the values of Example 11 are set at
100.
[0550] As Table 1 illustrates, it is understood that when any of
the amorphous alloy materials prepared in Examples 1-12 is used as
an electrode material constituting the anode of a rechargeable
lithium battery, there can be attained a high performance
rechargeable lithium battery which excels in the battery capacity
and charge-and-discharge Coulombic efficiency and markedly excels
particularly in the charging and discharging cycle life.
[0551] As detailed in the above, according to the present
invention, it is possible to stably produce a highly reliable
electrode material for a rechargeable lithium battery at a high
yield and a reasonable production cost, said electrode material
comprising a specific amorphous alloy material (particulate) which
has excellent characteristics and comprises particles which are
complete and uniform in terms of particle form and which contain
impurity a little.
[0552] The use of said electrode material makes it possible to
industrially produce a high performance rechargeable lithium
battery having excellent battery characteristics and a prolonged
charging and discharging cycle life at a reasonable production
cost.
1 TABLE 1 charge-and- discharge charging and battery Coulombic
discharging capacity *1 efficiency *2 cycle life *3 Example 1 100
100 100 Example 2 109 106 122 Example 3 105 98 101 Example 4 100
101 107 Example 5 98 99 103 Example 6 100 99 95 Example 7 95 93 91
Example 8 110 105 131 Example 9 109 100 100 Example 12 101 100 101
Comparative 111 65 48 Example 1 Comparative 59 53 19 Example 2
Comparative 110 62 42 Example 3 Comparative 105 43 23 Example 4
Example 10 100 100 100 Comparative 102 87 57 Example 5 Example 11
100 100 100 Comparative 107 75 51 Example 6 *1: A value per unit
weight obtained from a discharged electricity quantity provided in
the third cycle. The value of each of Examples 2-9 and 12 and
Comparative Examples 1-4 is a value relative to the value of
Example 1, which is set at 100.
[0553] The value of Comparative Example 5 is a value relative to
the value of Example 10, which is set at 100. The value of
Comparative Example 6 is a value relative to the value of Example
11, which is set at 100.
[0554] *2: A value based on a proportion of the discharges electric
quantity to the charged electric quantity in the capacity test. The
value of each of Examples 2-9 and 12 and Comparative Examples 1-4
is a value relative to the value of Example 1, which is set at 100.
The value of Comparative Example 5 is a value relative to the value
of Example 10, which is set at 100. The value of Comparative
Example 6 is a value relative to the value of Example 11, which is
set at 100.
[0555] *3: A value based on the number of the charging and
discharging cycles when the initial battery capacity became less
than 60% in the charging and discharging cycle test. The value of
each of Examples 2-9 and 12 and Comparative Examples 1-4 is a value
relative to the value of Example 1, which is set at 100. The value
of Comparative Example 5 is a value relative to the value of
Example 10, which is set at 100. The value of Comparative Example 6
is a value relative to the value of Example 11, which is set at
100.
* * * * *