U.S. patent application number 16/014636 was filed with the patent office on 2018-10-18 for non-aqueous electrolyte secondary battery.
This patent application is currently assigned to GS YUASA INTERNATIONAL LTD.. The applicant listed for this patent is Toshiyuki AOKI, Katsushi NISHIE, Toru TABUCHI, Minoru TESHIMA. Invention is credited to Toshiyuki AOKI, Katsushi NISHIE, Toru TABUCHI, Minoru TESHIMA.
Application Number | 20180301700 16/014636 |
Document ID | / |
Family ID | 29424659 |
Filed Date | 2018-10-18 |
United States Patent
Application |
20180301700 |
Kind Code |
A1 |
TABUCHI; Toru ; et
al. |
October 18, 2018 |
NON-AQUEOUS ELECTROLYTE SECONDARY BATTERY
Abstract
The present invention provides a non-aqueous electrolyte
secondary battery including a positive electrode, a negative
electrode having a negative active material, and a non-aqueous
electrolyte, characterized in that the negative active material
contains composite particle (C), which has silicon-containing
particle (A) and electronic conductive additive (B), the
silicon-containing particle (A) has a content of carbon, and when
measured at a temperature rising rate of 10.+-.2.degree. C./min by
thermogravimetry, said composite particle (C) exhibits two stages
of weight loss in the range of 30 to 1000.degree. C.
Inventors: |
TABUCHI; Toru; (Kyoto-shi,
JP) ; AOKI; Toshiyuki; (Kyoto-shi, JP) ;
TESHIMA; Minoru; (Kyoto-shi, JP) ; NISHIE;
Katsushi; (Kyoto-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
TABUCHI; Toru
AOKI; Toshiyuki
TESHIMA; Minoru
NISHIE; Katsushi |
Kyoto-shi
Kyoto-shi
Kyoto-shi
Kyoto-shi |
|
JP
JP
JP
JP |
|
|
Assignee: |
GS YUASA INTERNATIONAL LTD.
KYOTO
JP
|
Family ID: |
29424659 |
Appl. No.: |
16/014636 |
Filed: |
June 21, 2018 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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14878624 |
Oct 8, 2015 |
10038186 |
|
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16014636 |
|
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14096268 |
Dec 4, 2013 |
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14878624 |
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13187550 |
Jul 21, 2011 |
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14096268 |
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10513664 |
Jan 20, 2006 |
8092940 |
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PCT/JP03/05654 |
May 6, 2003 |
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13187550 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H01M 2004/027 20130101;
H01M 4/62 20130101; H01M 4/133 20130101; H01M 10/0525 20130101;
H01M 4/366 20130101; H01M 4/48 20130101; H01M 4/134 20130101; H01M
4/625 20130101; H01M 4/587 20130101; H01M 4/364 20130101; H01M
2004/021 20130101; Y02E 60/10 20130101; H01M 4/386 20130101; H01M
4/131 20130101; H01M 4/483 20130101 |
International
Class: |
H01M 4/48 20060101
H01M004/48; H01M 4/38 20060101 H01M004/38; H01M 10/0525 20060101
H01M010/0525; H01M 4/62 20060101 H01M004/62; H01M 4/36 20060101
H01M004/36 |
Foreign Application Data
Date |
Code |
Application Number |
May 8, 2002 |
JP |
2002-132786 |
Jun 17, 2002 |
JP |
2002-176350 |
Oct 18, 2002 |
JP |
2002-304654 |
Oct 28, 2002 |
JP |
2002-312340 |
Claims
1-6. (canceled)
7. A non-aqueous electrolyte secondary battery comprising: a
positive electrode; a negative electrode; and a non-aqueous
electrolyte, wherein the negative electrode contains a negative
active material, the negative active material contains a composite
particle (C), the composite particle (C) contains a
silicon-containing particle (A) and an electron-conductive additive
(B), the electron-conductive additive (B) covers the surface of the
silicon-containing particle (A), and the silicon-containing
particle (A) comprises equimolar amounts of Si and O.
8. The non-aqueous electrolyte secondary battery according to claim
7, wherein the weight of the electron-conductive additive (B) falls
within the range of 0.5 wt. % to 60 wt. % of the composite particle
(C).
9. The non-aqueous electrolyte secondary battery according to claim
7, the composite particles further containing carbon and the
silicon-containing particle (A) and carbon are coated by the
electron-conductive additive (B).
10. The non-aqueous electrolyte secondary battery according to
claim 7, wherein the electron-conductive additive (B) contains a
carbon material having an average interplanar spacing d(002) of
0.3354 nm or more and less than 0.34 nm.
11. The non-aqueous electrolyte secondary battery according to
claim 7, wherein the electron-conductive additive (B) is
carbon.
12. The non-aqueous electrolyte secondary battery according to
claim 7, wherein at least one of half widths of the Si (111)-plane
and Si (220)-plane diffraction peaks of the silicon-containing
particle (A) in X-ray diffraction measurement with CuK.alpha.
radiation is less than 3.degree. (2.theta.).
13. The non-aqueous electrolyte secondary battery according to
claim 7, wherein the negative active material further contains a
carbon material (D).
14. A method of making the non-aqueous electrolyte secondary
battery of claim 7 comprising: calcinating SiO at a range of
temperature from 900.degree. C. to 1400.degree. C. and separating
SiO into Si and SiO.sub.2 to make a particle including a
microcrystalline silicon phase and an amorphous SiO.sub.2
phase.
15. The method according to claim 14, wherein SiO is calcinated in
N.sub.2 or Ar.
16. The method according to claim 14 further comprising chemically
depositing, concurrently with the calcinating, carbon on the
surface of the particle.
17. A method of making a negative active material comprising:
calcinating SiO at a range of temperature from 900.degree. C. to
1400.degree. C. and separating SiO into Si and SiO.sub.2 to make a
particle including a microcrystalline silicon phase and an
amorphous SiO.sub.2 phase.
18. The method of making a negative active material according to
claim 17, wherein SiO is calcinated in N.sub.2 or Ar.
19. The method of making a negative active material according to
claim 17 further comprising chemically depositing, concurrently
with the calcinating, carbon on the surface of the particle.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This is a continuation of Ser. No. 14/096,268 filed Dec. 4,
2013, which is a divisional of Ser. No. 13/187,550 filed Jul. 21,
2011, now abandoned, which is a divisional of application Ser. No.
10/513,664 filed Nov. 8, 2004, now U.S. Pat. No. 8,092,940, which
is the National Stage of PCT/JP03/05654 filed May 6, 2003; the
above noted prior applications are all hereby incorporated by
reference.
TECHNICAL FIELD
[0002] The present invention relates to a non-aqueous electrolyte
secondary battery.
BACKGROUND ART
[0003] In the past, carbon material has been used mainly as a
negative active material for lithium-ion secondary batteries.
[0004] These days, however, in the batteries which utilize carbon
material as a negative active material, the discharge capacity is
so enhanced as to be close to the theoretical capacity of carbon
material. Such a present situation makes it difficult to further
improve the discharge capacity of those batteries.
[0005] In recent years, therefore, high-capacity negative active
materials which can be alternatives to carbon material have been
studied thoroughly. As one example of such high-capacity negative
active materials, silicon material can be included (refer to
Provisional Publication No. 29602 of 1995, for example.)
[0006] With silicon being used as a negative active material,
however, a battery significantly deteriorates in cycle performance
compared to a case of carbon material being used as a negative
active material. The reasons for this can be explained as follows:
having a large volume expansion associated with absorption of
lithium ion, silicon is pulverized easily due to the repetition of
charge/discharge; such pulverization creates a portion where a
conductive pathway is broken and causes a decrease in current
collection efficiency; and, consequently, as the number of
charge/discharge cycles grows, the capacity decreases rapidly and
the cycle life becomes short.
[0007] As described in USP200210086211 and EP1205989A2, Provisional
Publication No. 3920 of 1998, and Provisional Publication No.
215887 of 2000, it is proposed that a non-aqueous electrolyte
secondary battery utilize the silicon which is coated with carbon
material, as a negative active material, in that the carbon
material-coated silicon shows better cycle performance than the one
without coating.
[0008] However, as compared to a conventional lithium ion battery
where carbon material is used as a negative active material, the
cycle performance of the above proposed battery is still
unsatisfactory.
[0009] The present invention has been conducted in view of such
circumstances. It is an object of the invention to provide a
non-aqueous electrolyte battery having a large capacity and a
satisfactory cycle life.
DISCLOSURE OF THE INVENTION
[0010] The present invention of claim 1 provides a non-aqueous
electrolyte secondary battery comprising a positive electrode, a
negative electrode having a negative active material, and a
non-aqueous electrolyte; characterized in that the negative active
material contains the composite particle (C), which has
silicon-containing particle (A) and electronic conductive additive
(B), and carbon material (D), and that the weight of the electronic
conductive additive (B) falls within the range of 0.5 wt. % to 60
wt. % to the weight of the composite particle (C).
[0011] According to the present invention, the said negative active
material contains the composite particle (C), in which the
silicon-containing particle (A) and the electronic conductive
additive (B) are contained, and the carbon material (D), and hence
the cycle life improves. The reasons for this have not been
determined yet clearly; however, it is very likely that the
presence of the electronic conductive additive (B) and the carbon
material (D) causes the enhancement of the contact conductivity
between the silicon-containing particle (A) and between the
composite particle (C), respectively.
[0012] In addition, the weight of the electronic conductive
additive (B) falls within the range of 0.5 wt. % to 60 wt. % to the
weight of the composite particle (C), and hence the discharge
capacity and the cycle performance improve. If the weight of the
electronic conductive additive (B) is less than 0.5 wt. % to the
weight of the composite particle (C), the amount of the electronic
conductive additive (B) becomes insufficient to the amount of the
silicon-containing particle (A), so that inadequate electronic
conductivity causes the deterioration of the cycle performance.
Meanwhile, if the weight of the electronic conductive additive (B)
is greater than 60 wt. %, the discharge capacity per active
material weight is reduced and, consequently, the battery discharge
capacity becomes small.
[0013] The present invention of claim 2 is characterized in that,
in the non-aqueous electrolyte secondary battery of the present
invention of claim 1, the silicon-containing particle (A) has a
content of carbon, and that the composite particle (C) is
configured by coating the silicon-containing particle (A) with the
electronic conductive additive (B).
[0014] According to the invention of claim 2, the
silicon-containing particle (A) has a content of carbon, and hence
the contact conductivity of silicon becomes better and this results
in improvement in the cycle life. In addition, the composite
particle (C) is configured by coating the silicon-containing
particle (A) with the electronic conductive additive (B), and hence
the cycle life improves. It is believed that the reason for this
may be that since the particle (A) is coated with the electronic
conductive additive (B), even when the active material is
pulverized due to the active material expansion/contraction that
occurs during charge/discharge, the deterioration of the contact
conductivity is prevented.
[0015] The present invention of claim 3 is characterized in that,
in the non-aqueous electrolyte secondary battery of the present
invention of above stated claim 1 or claim 2, the proportion of the
weight of the composite particle (C) to the total weight of the
composite particle (C) and the carbon material (D) falls within the
range of 60 wt. % to 99.5 wt. %.
[0016] According to the invention of claim 3, the proportion of the
weight of the composite particle (C) to the total weight of the
composite particle (C) and the carbon material (D) falls within the
range of 60 wt. % to 99.5 wt. %, and hence the discharge capacity
and the cycle life improve. If the proportion of the weight of the
composite particle (C) to the total weight of the composite
particle (C) and the carbon material (D) is less than 60 wt. %, the
negative active material becomes insufficient, so that the
discharge capacity decreases. If the proportion of the weight of
the composite particle (C) is greater than 99.5 wt. %, the contact
conductivity between the active material deteriorates, so that the
cycle life is reduced.
[0017] The present invention of claim 4 is characterized in that,
in the non-aqueous electrolyte secondary battery of the present
invention of above stated claim 1 or claim 2, silicon oxide
SiO.sub.x (where 0<X.ltoreq.2) is contained in the composite
particle (C).
[0018] According to the invention of claim 4, silicon oxide
SiO.sub.x (where 0<X.ltoreq.2) is contained in the composite
particle (C), and hence the cycle life improves. It is believed
that the reason for this may be that changes in volume during
charge/discharge are smaller in silicon oxide SiO.sub.x (where
0<X.ltoreq.2) as compared to those in silicon.
[0019] The present invention of claim 5 is characterized in that,
in the non-aqueous electrolyte secondary battery of the present
invention of above stated claim 4, the proportion of the weight of
the composite particle (C) to the total weight of the composite
particle (C) and the carbon material (D) falls within the range of
1 wt. % to 30 wt. %.
[0020] Since the discharge capacity decreases, it is not preferable
that the proportion of the weight of the composite particle (C) to
the total weight of the composite particle (C) and the carbon
material (D) be less than 1 wt. %. In addition, it is not
preferable either that the proportion of the weight of the
composite particle (C) to the total weight of the composite
particle (C) and the carbon material (D) be greater than 30 wt. %,
since the negative active material significantly expands and
contracts during charge/discharge and, as a result, the cycle
performance deteriorates. It is more preferable that the proportion
of the weight of the composite particle (C) to the total weight of
the composite particle (C) and the carbon material (D) fall within
the range of 5 wt. % to 10 wt. %.
[0021] The present invention of claim 6 provides a non-aqueous
electrolyte secondary battery comprising a positive electrode, a
negative electrode having a negative active material, and a
non-aqueous electrolyte; characterized in that said negative active
material has silicon-containing particle (A), and that said
silicon-containing particle (A) contains silicon oxide SiO.sub.x
(where 0<X.ltoreq.2) and carbon.
[0022] According to the invention of claim 6, silicon oxide
SiO.sub.x (where 0<X.ltoreq.2) is contained in the composite
particle (C), and hence the cycle life improves. It is believed
that the reason for this may be that changes in volume during
charge/discharge are smaller in silicon oxide SiO.sub.x (where
0<X.ltoreq.2) as compared to those in silicon.
[0023] In addition, carbon is contained in the composite particle
(C), and hence the cycle life improves. The reason for this is that
even when silicon or SiO.sub.x is pulverized during
charge/discharge, a conductive pathway is kept by carbon, so that a
decrease in the current collection efficiency can be inhibited.
[0024] The present invention of claim 7 provides a non-aqueous
electrolyte secondary battery comprising a positive electrode, a
negative electrode having a negative active material, and a
non-aqueous electrolyte; characterized in that the negative active
material contains the composite particle (C), which has
silicon-containing particle (A) and electronic conductive additive
(B), that the composite particle (C) has a content of carbon, and
that when measured at a temperature rising rate of 10.+-.2.degree.
C./min by thermogravimetry, the composite particle (C) exhibits two
stages of weight loss in the range of 30 to 1000.degree. C.
[0025] According to the invention of claim 7, the composite
particle (C) has a content of carbon and when measured at a
temperature rising rate of 10.+-.2.degree. C./min by
thermogravimetry, it exhibits two stages of weight loss in the
range of 30 to 1000.degree. C., and hence the cycle performance is
improved. The reasons for this can be explained as follows. Weight
loss hardly occurs to silicon at a temperature range of 30 to
1000.degree. C.; therefore, it is carbon that causes weight loss in
such a temperature range. Carbon, depending on the different
properties, will differ in the temperature at which weight loss
starts. In the present invention, therefore, at least two different
kinds of carbon should be contained in the composite particle (C).
And containing different kinds of carbon in the negative active
material allows the silicon expansion/contraction that occurs
during charge/discharge to be reduced and, consequently, the
contact conductivity in the particle of the negative active
material can be retained.
BRIEF DESCRIPTION OF THE DRAWINGS
[0026] FIG. 1 is a view showing TG measurement results.
[0027] FIG. 2 is a view showing the cross sectional configuration
of a prismatic battery used in Embodiment A.
[0028] FIG. 3 is a view showing the cross sectional configuration
of a prismatic battery used in Embodiment B.
[0029] FIG. 4 is a schematic view showing the cross section of a
composite particle used in Embodiment C.
[0030] FIG. 5 is a schematic view showing the cross section of a
composite particle used in Embodiment C.
[0031] FIG. 6 is a schematic view showing the cross section of a
composite particle used in Embodiment C.
[0032] FIG. 7 is a schematic view showing the cross section of a
composite particle used in Embodiment C.
[0033] FIG. 8 is a view showing a mixture of carbon material (D)
and composite particles (C).
PREFERRED EMBODIMENTS OF THE INVENTION
[0034] Hereinafter, an embodiment of the present invention will be
described with reference to the accompanying drawings.
[0035] As a negative active material in the present invention, it
is possible to use a material which contains the composite particle
(C), in which silicon-containing particle (A) and electronic
conductive additive (B) are contained, and carbon material (D).
[0036] As the silicon-containing particle (A) in the present
invention, it is possible to use, for example, the following
particles: silicon particle, silicon oxide particle, or the silicon
particle or silicon oxide particle which has at least one element
selected from the group consisting of the typical nonmetallic
elements such as B, N, P, F, Cl, Br, and I; the typical metallic
elements such as Li, Na, Mg, Al, K, Ca, Zn, Ga, and Ge; and the
transition metallic elements such as Sc, Ti, V, Cr, Mn, Fe, Co, Ni,
Cu, Mo, Zr, Ta, Hf, Nb, and W. These may be used alone or in
combination with two or more.
[0037] As the electronic conductive additive (B) in the present
invention, it is possible to use, for example, Cu, Ni, Ti, Sn, Al,
Co, Fe; Zn, Ag or alloy of two or more of these elements, or carbon
material. Among these, it is more preferable to use carbon
material.
[0038] Regarding the methods of coating the particle (A) with
carbon material as the electronic conductive additive (B) in the
present invention, the following techniques can be used. In CVD
method, benzene, toluene, xylene, methane, ethane, propane, butane,
ethylene, or acetylene, as a carbon source, is decomposed in
gaseous phase and chemically deposited on the surface of the
particle (A). In another method, the particle (A) is mixed with
pitch, tar, or thermoplastic resin (for example, furfuryl alcohol)
and then calcinated. And in another method, a mechanochemical
reaction is used, where mechanical energy is applied between the
particle (A) and the carbon material with which the particle (A) is
coated so that a composite can be formed. Among these methods,
because of the uniformity in the carbon material coating, it is
preferable to use CVD method.
[0039] When Cu, Ni, Ti, Sn, Al, Co, Fe, Zn, or Ag is used as the
electronic conductive additive (B) in the present invention, it is
possible to use, for example, CVD method, spatter evaporation
method, or plating method.
[0040] In the present invention, it is preferable that the
proportion of the weight of the electronic conductive additive (B)
to the weight of the composite particle (C) fall within the range
of 0.5 wt. % to 60 wt. %, more preferably in the range of 1 wt. %
to 60 wt. %, and even more preferably in the range of 5 wt. % to 40
wt. %. If the proportion exceeds 60 wt. %, a large discharge
capacity cannot be attained. And if it is less than 0.5 wt. %, the
contact conductivity of the silicon-containing particle (A)
deteriorates and, as a result, the cycle life is reduced.
[0041] In addition, as the electronic conductive additive (B),
carbon material in a variety of crystal forms can be used.
Especially, it is preferable to utilize the carbon material that
has 0.3354 to 0.35 nm in the average interplanar spacing d (002),
which is obtained by conducting X-ray diffraction on the carbon on
the particle (A). Within such a range, it is possible to attain a
large initial discharge capacity and a high capacity retention
ratio according to cycle. The measurement of d (002) can be carried
out using, for example, a X-ray diffractometer RINT2000 (Rigaku)
with the use of Cuk.alpha. radiation.
[0042] The average interplanar spacing d (002) of the carbon
material which is used as the electronic conductive additive (B) in
the present invention can be adjusted in the following manner. For
example, when the particle (A) is mixed with thermoplastic resin
and then calcinated, the distance can be adjusted by means of a
calcination temperature. In addition, when the particle (A) is
coated with carbon using CVD technique, it can be adjusted by means
of a CVD temperature. It is preferable that the average interplanar
spacing d (002) lie in the range of 0.3354 to 0.35 nm: for example,
when a large value of approximately 0.35 nm is desirable, a
calcination temperature or CVD temperature can be set at
approximately 1000.degree. C., and when a small value of
approximately 0.3354 nm is desirable, a calcination temperature or
CVD temperature can be set higher than approximately 1000.degree.
C. and not higher than approximately 3000.degree. C. With a
processing temperature being set lower, the average interplanar
spacing d (002) tends to be larger. In order to keep the average
interplanar spacing d (002) as small as possible, with a processing
temperature remaining low, the carbon can be made to grow on the
surface of the particle (A) as slow as possible using an organic
matter having a benzene ring such as benzene, as a carbon source
for CVD.
[0043] When a mechanochemical reaction is employed as the
compounding technique, the average interplanar spacing d (002) of
0.3354 nm can be obtained by using natural graphite microparticle.
Furthermore, it is possible to attain the average interplanar
spacing d (002) of approximately 0.346 nm by using the carbon
particle which is prepared by calcinating coke at approximately
1000.degree. C.
[0044] Moreover, when silicon particle is used as the particle (A),
the preferable BET specific surface area lies in the range of 1.0
to 10.0 m.sup.2/g. In addition, if the BET specific surface area of
the composite particle (C) exceeds 10.0 m.sup.2/g when silicon
particle is used as the particle (A), undesirable results are
generated as follows: binding effect between the active material by
the use of a binder becomes less strong, the negative active
material expansion/contraction during charge/discharge causes gaps
to occur between the negative active material, the electrical
connection between the negative active material is broken, and as a
result, the cycle performance decreases. Therefore, it is
preferable that the BET specific surface area of the composite
particle (C) be not greater than 10.0 m.sup.2/g. The BET specific
surface area can be measured by using, for example, GEMINI2375
(SHIMADZU).
[0045] The BET specific surface area of the composite particle (C)
in the present invention can be adjusted in the following manner.
For example, when the particle (A) is coated with the electronic
conductive additive (B) by means of CVD, by applying a large amount
of coating, the BET specific surface area can be reduced. Moreover,
by controlling the particle size distribution with the use of a
sieve, the BET specific surface area can be adjusted, too. More
specifically, with an increase in the amount of the particle whose
particle size is small, the BET specific surface area becomes
large, and with an increase in the amount of the particle whose
particle size is large, it becomes small.
[0046] As the carbon material (D) in the present invention, it is
possible to use one or more materials selected from the group
consisting of natural graphite, artificial graphite, acetylene
black, ketjen black, or vapor grown carbon fiber. Concerning the
shape of the carbon material (D), a variety of shapes can be used
including spherical, filamentous, and scale-like shapes. Among
them, because of its capability of fully securing the electronic
conductivity, it is preferable to use the graphite of a scale-like
shape, the number average particle size of which ranges from 1 to
15 .mu.m. In addition, from the perspective of improving the cycle
performance, meso carbon micro beads or meso carbon fibers, or the
material prepared by adding boron to either of such carbon
materials can be used.
[0047] Moreover, when the silicon-containing particle (A) has a
content of carbon and the composite particle (C) is configured by
coating the particle (A) with the electronic conductive additive
(B), the cycle performance can further improve. Allowing for
satisfactory cycle performance, the preferable proportion of the
weight of the component other than carbon to the weight of the
particle (A) falls within the range of 10 wt. % to 70 wt. %, more
preferably in the range of 20 wt. % to 70 wt. %.
[0048] Furthermore, when SiO.sub.x (where 0<X.ltoreq.2) is not
contained in the composite particle (C), the preferable proportion
of the weight of the composite particle (C) to the total weight of
the composite particle (C) and the carbon material (D) falls within
the range of 60 wt. % to 99.5 wt. %, in order for the cycle
performance to improve and for the capacity to be secured.
[0049] By using the composite particle (C) in which silicon oxide
SiO.sub.x (where 0<X.ltoreq.2) is contained, more satisfactory
cycle performance can be achieved. It is believed that the reason
for this is that volume expansion can be inhibited because of the
inclusion of SiO.sub.x. It is possible to use Si particle and
SiO.sub.x particle by mixture, or the particle which contains both
Si and SiO.sub.x (where 0<X.ltoreq.2) phases may also be
used.
[0050] It is preferable that the silicon oxide which is contained
in the composite particle (C) have both Si and SiO.sub.x (where
0<X.ltoreq.2) phases. This is possibly due to the following
reasons. In the material which contains both Si and SiO.sub.x
(where 0<X.ltoreq.2) phases, lithium is absorbed/desorbed in Si
which disperses in SiO.sub.2 matrix and, as a result, the volume
expansion of Si is inhibited, so that the cycle performance becomes
excellent. Therefore, by mixing both phases at an optimal
proportion, it is possible to obtain a negative active material
having a large discharge capacity and excellent cycle
performance.
[0051] The material which contains both Si and SiO.sub.x (where
0<X.ltoreq.2) phases can be obtained as follows. For example,
when SiO is calcinated in N.sub.2 or Ar at a range of temperature
from 900.degree. C. to 1400.degree. C., SiO starts separating into
Si and SiO.sub.2 at approximately 900.degree. C. and the separation
is almost complete at 1400.degree. C. In this case, when a larger
amount of Si is desirable, the temperature can be set higher, and
when a smaller amount of Si is desirable, the temperature can be
set lower.
[0052] In addition, the material which contains both Si and
SiO.sub.x (where 0<X.ltoreq.2) phases can be identified in the
following manner. First, Si powder and SiO.sub.2 powder are mixed
at different ratios to prepare standard samples. For these standard
samples, NMR measurement is performed to examine changes in the Si
and SiO.sub.2 peaks at different mixture ratios. Next, for the
material which contains both Si and SiO.sub.x (where
0<X.ltoreq.2) phases, NMR measurement is performed. By making a
comparison between the measurement result obtained and those of
standard samples, the peaks of Si and SiO.sub.2 are identified, and
furthermore the value of X for SiO.sub.x can be obtained by
determining the ratios of Si and SiO.sub.2.
[0053] In the X-ray diffraction measurement conducted by the use of
the CuK.alpha. radiation on the material which contains both Si and
SiO.sub.x (where 0<X.ltoreq.2) phases, it is preferable that at
least one of the half widths of the Si (111)-plane and Si
(220)-plane diffraction peaks be less than 3.degree. (2 .theta.).
The reason for this is that when the material the half width of
which is not smaller than 3.degree. (2 .theta.) is used, the cycle
performance decreases. In addition, when silicon oxide is
contained, in order to further improve the cycle performance, it is
preferable that the proportion of the weight of the composite
particle (C) to the total weight of the composite particle (C) and
the carbon material (D) fall within the range of 1 wt. % to 30 wt.
%, or more preferably, within the range of 5 wt. % to 10 wt. %.
[0054] Moreover, the preferable proportion of the weight of Si to
the total weight of Si and SiO.sub.x falls within the range of 20
wt. % to 80 wt. %. The reason for this is that since Si exhibits a
larger discharge capacity than SiO.sub.x, if the proportion of the
weight of Si is less than 20 wt. %, the discharge capacity
decreases; and that, on the other hand, since SiO.sub.x exhibits
smaller volume expansion during charge/discharge and more excellent
cycle performance than Si, if the proportion of the weight of Si is
greater than 80 wt. %, the cycle performance deteriorates.
[0055] Furthermore, when the particle (A) comprising silicon oxide
SiO.sub.x is used and carbon material is used as the electronic
conductive additive (B), if the proportion of the carbon material
contained in the composite particle to the negative active material
is less than 3 wt. %, the following undesirable result is
generated: the particles consisting of Si, the particles consisting
of SiO.sub.x, or the particles containing Si and SiO.sub.x are
pulverized due to the repetition of charge/discharge, the breakage
of conductive pathway caused by such pulverization cannot be
prevented, and as a result, the cycle performance deteriorates. In
addition, the proportion being greater than 60 wt. % is not
preferred either because the discharge capacity is caused to
decrease. Therefore, it is preferable that the proportion of the
carbon material on the surface of the composite particle to the
entire negative active material fall within the range of 3 wt. % to
60 wt. %.
[0056] In addition, among those composing the silicon-containing
particle (A), the particle consisting of Si, the particle
consisting of SiO.sub.x (where 0<X.ltoreq.2), or the particle
containing Si and SiO.sub.x (where 0<X.ltoreq.2) can be used in
either highly crystalline or amorphous state: however, amorphous
state is preferable. The reason for this is that if the particle
changes from a highly crystalline structure into an amorphous
structure due to charge/discharge, there is a possibility that
electric potential of the negative active material may vary.
Therefore, in order to prevent electric potential variation from
occurring during charge/discharge, it is preferable to use an
amorphous structure in advance.
[0057] In addition, regarding the particle consisting of Si, the
particle consisting of SiO.sub.x (where 0<X.ltoreq.2), or the
particle containing Si and SiO.sub.x (where 0<X.ltoreq.2), the
following can also be used: the particles which have been washed
with acid such as fluorinated acid or sulfuric acid, or the
particles which have been reduced with hydrogen.
[0058] Moreover, from the standpoint of improvement in the cycle
performance, when the silicon-containing particle (A) has a content
of carbon, the preferable proportion of the weight of silicon to
the weight of the silicon-containing particle (A) falls within the
range of 10 wt. % to 70 wt. %, or more preferably within the range
of 20 wt. % to 70 wt. %.
[0059] In addition, when carbon material is used as the electronic
conductive additive (B) for coating, the usable crystalline
material ranges from highly crystalline graphite to low crystalline
carbon. Especially, because of its low electrolyte-solution
reactivity, it is preferable to use low crystalline carbon.
[0060] Furthermore, it is preferable that the number average
particle size of the composite particle (C), which is configured by
coating the silicon-containing particle (A) with the electronic
conductive additive (B), range from 0.1 to 20 .mu.m. When the
composite particle (C) is configured by coating the
silicon-containing particle (A), which is made of silicon material
and carbon material, with the electronic conductive additive (B),
the preferable number average particle size ranges from 0.1 to 30
.mu.m. The particle having the number average particle size of
smaller than 0.1 .mu.m is difficult to be produced and hard to be
handled. And, the particle having the number average particle size
of greater than 30 .mu.m is inferior in the conductivity in the
active material and suffers a deterioration in the cycle
performance. The number average particle size of particles means
the number average particle size obtained by means of a laser
diffraction method. The number average particle size can be
measured using, for example, SALD2000J (SHIMADZU.)
[0061] The particle size of the composite particle (C) in the
present invention can be controlled by arranging the particle (A)
so as to exhibit a predetermined particle size by means of grinding
or screening with a sieve, and by adjusting the amount of the
electronic conductive additive (B) used for coating. The adjustment
of coating amount can be made by adjusting, for example, the time
required for CVD process.
[0062] The composite particle (C) described in the invention of
claim 7 is as follows: the composite particle (C) has a content of
carbon, and when the composite particle (C) is measured at a
temperature rising rate of 10.+-.2.degree. C./min by
thermogravimetry, weight loss appears at two stages in a range of
temperature from 30 to 1000.degree. C. The reason for this is that
using such composite particle (C) makes it possible to obtain a
non-aqueous electrolyte secondary battery which is excellent in
charge/discharge cycle performance and has a high energy
density.
[0063] In the above-described weight loss, the preferable
temperature at which weight loss starts in thermogravimetry of the
composite particle (C) is not higher than 600.degree. C. at the
first stage and is higher than 600.degree. C. at the second
stage.
[0064] In addition, in the above-described weight loss, the
preferable proportion of weight loss to the weight prior to the
temperature rise in thermogravimetry of the composite particle (C)
falls within the range of 3 to 30 wt. % at the first stage and 5 to
65 wt. % at the second stage.
[0065] Carbon will differ in the temperature at which weight loss
starts in thermogravimetry, depending on the different properties,
so that the nature of carbon can be characterized according to the
temperature at which weight loss starts. In addition, silicon
hardly decreases in weight at a temperature range of 30 to
1000.degree. C.
[0066] FIG. 1 shows the results of thermogravimetry of the
composite particle (C) satisfying the above requirements. In the
present invention, the temperature at which weight loss starts at
the first stage in thermogravimetry of the negative active material
refers to the temperature at point "a" in FIG. 1: at this point,
the DTG curve, obtained by taking the first derivative of the
region in a temperature range of 100.degree. C. to 350.degree. C.
on the TG line, starts to deviate from the line "c" in FIG. 1,
obtained by linearly approximating the DTG curve. In addition, the
temperature at which weight loss at the first stage ends refers to
the temperature at point "b" in FIG. 1: the local minimum point on
the DTG curve, or the point at the intersection of the first-stage
weight loss with the second-stage weight loss on the DTG curve,
more specifically, the point at which, after the DTG curve started
to exhibit the first-stage weight loss, it again changes the slope
of the curve and starts to exhibit another weight loss. In
addition, the temperature at which weight loss starts at the second
stage refers to the temperature at which weight loss newly starts,
exceeding the temperature at which the first-stage weight loss
ends.
[0067] In order to achieve excellent charge/discharge cycle
performance in the negative electrode, the preferable temperature
at which weight loss starts in thermogravimetry of the negative
active material is not lower than 350.degree. C. at the first stage
and not higher than 800.degree. C. at the second stage.
[0068] The first-stage weight loss means the amount of weight loss
in the temperature rising period from the temperature at which
weight loss starts, to the temperature at which weight loss ends at
the first stage. Likewise, the second-stage weight loss means the
amount of weight loss in the temperature rising period from the
temperature at which weight loss starts to the temperature at which
weight loss ends at the second stage. In addition, weight loss in
the present invention refers to the amount of weight loss to the
weight of the negative active material prior to the temperature
rise.
[0069] In the silicon-carbon composite used as an active material
in the present invention, the temperature at which weight loss
starts and the amount of weight loss in thermogravimetry can be
controlled in the following manner.
[0070] Carbon powder is added to silicon powder, these powders are
mixed and ground in a ball mill, and then granulated bodies of
silicon and carbon are prepared. The granulated particle thus
prepared is put into a stainless steel container, a nitrogen
atmosphere is created entirely in the stainless steel container
while the container is agitated, the internal temperature is then
raised up to nearly 1000.degree. C., subsequently benzene vapor is
introduced in said stainless steel container, and CVD process is
executed to coat the granulated body with carbon material. After
that, the temperature is lowered down to the room temperature under
nitrogen atmosphere, and a negative active material can be
obtained. As silicon material other than silicon powder, it is also
possible to use silicon oxides or their mixtures. In this case,
with CVD temperature being maintained lower than 1100.degree. C.,
the temperature at which weight loss starts at the first stage can
be kept not higher than 600.degree. C.
[0071] Various negative active materials, different in the
temperature at which weight loss starts and the amount of weight
loss in thermogravimetry, can be prepared by changing the following
factors: the average particle size of silicon material; the average
particle size, specific surface area, and average interplanar
spacing d (002) of carbon powder; the mixture ratio of silicon
powder to carbon powder; the mixed grinding time in a ball mill;
and the type of organic constituent vapor to be introduced in a
container, temperature, and time for CVD process.
[0072] As a binder to be used in the negative electrode, a variety
of materials are usable accordingly without special limitation. For
example, the following materials or derivatives thereof can be used
alone or in combination with two or more: styrene-butadiene rubber
(SBR) or carboxymethyl-cellulose (CMC), poly(vinylidene fluoride),
carboxy poly(vinylidene fluoride), poly(tetrafluoroethylene), poly
(tetrafluoroethylene-hexafluoroethylene),
poly(tetrafluoroethylene-hexafluoropropylene), vinylidene
fluoride-chlorotrifluoroethylene copolymer, poly(vinylidene
fluoride-hexafluoropropylene), ethylene-propylene-diene copolymer,
acrylonitrile-butadiene rubber, fluoro rubber, polyvinyl acetate,
poly-methyl methacrylate, nitrocellulose, polyethylene, or
polypropylene.
[0073] As a solvent or solution to be used when the negative active
material and the binder are compounded, it is possible to use a
solvent or solution which is capable of dissolving or dispersing
the binder; for example, non-aqueous solvent or aqueous solution.
The following can be included as an example of non-aqueous solvent:
n-methyl-2-pyrrolidone, dimethyl formamide, dimethyl acetamide,
methyl ethyl ketone, cyclohexanone, methyl acetate, methyl
acrylate, diethyl triamine, n,n-dimethyl amino propyl amine,
ethylene oxide, and tetrahydrofuran.
[0074] As a current collector of the negative electrode, usable
materials include iron, copper, stainless, or nickel. Concerning
its configuration, the following shapes can be used: sheet, plane,
network, foam, sintered porosity, and expanded lattice. It is also
possible to use the one which is configured by putting a hole in
any shape in a material which has been formed into the above-listed
shape.
[0075] As a positive active material to be used in the present
invention, a variety of materials are usable accordingly without
special limitation. For example, the transition metallic compounds
such as manganese dioxide or vanadium pentoxide; the transition
metallic chalcogenides such as iron sulfide or titanium sulfide;
the composite oxides of such transition metal and lithium,
Li.sub.xMO.sub.2-.delta. (composite oxides where M represents Co,
Ni, or Mn, 0.4.ltoreq.X.ltoreq.1.2, and
0.ltoreq..delta..ltoreq.0.5); or such composite oxides which
contain at least one element selected from the group consisting of
Al, Mn, Fe, Ni, Co, Cr, Ti, and Zn, or nonmetallic element such as
P or B. It is also possible to use lithium-nickel composite oxides,
or the positive active materials represented by.
Li.sub.xNi.sub.pM1.sub.qM2.sub.rO.sub.2-.delta. (composite oxides
where M1 and M2 represent at least one element selected from the
group consisting of Al, Mn, Fe, Ni, Co, Cr, Ti, and Zn, or
nonmetallic element such as P or B; 0.4.ltoreq.X.ltoreq.1.2,
0.8.ltoreq.p+q+r.ltoreq.1.2, and 0.ltoreq..delta..ltoreq.0.5.)
Among them, capable of attaining high voltage and high energy
density, and also superior in cycle performance, lithium-cobalt
composite oxides or lithium-cobalt-nickel composite oxides are
preferred.
[0076] As a binder to be used in the positive electrode, a variety
of materials are usable accordingly without special limitation. For
example, the following materials or derivatives thereof can be used
alone or in combination with two or more: poly(vinylidene
fluoride), poly (vinylidene fluoride-hexafluoropropylene), poly
(tetrafluoroethylene), fluorinated poly(vinylidene fluoride),
ethylene-propylene-diene methylene linkage, styrene-butadiene
rubber, acrylonitrile-butadiene rubber, fluoro rubber, polyvinyl
acetate, poly-methyl methacrylate, polyethylene, or
nitrocellulose.
[0077] As an electronic conductive additive to be used in the
positive electrode, a variety of materials are usable accordingly
without special limitation. For example, Ni, Ti, Al, Fe or alloy of
two or more of these elements, or carbon material can be used.
Among these, it is preferable to use carbon material. As some
examples of carbon material, the following amorphous carbon can be
listed: natural graphite, artificial graphite, vapor grown carbon
fiber, acetylene black, ketjen black, and needle coke.
[0078] As an organic solvent for the electrolyte solution to be
used in the present invention, a variety of solvents are usable
accordingly without special limitation. For example, ethers,
ketones, lactones, nitriles, amines, amides, sulfur compounds,
halogenated hydrocarbons, esters, carbonates, nitro compounds,
phosphate ester compounds, and sulfolane hydrocarbons can be used.
Among these, it is preferable to use ethers, ketones, esters,
lactones, halogenated hydrocarbons, carbonates, or sulfolane
hydrocarbons.
[0079] Furthermore, as some examples of these, there are
tetrahydrofuran, 2-methyl tetrahydrofuran, tetrahydropyran,
1,4-dioxan, anisole, monoglyme, 4-methyl-2-pentanone, methyl
acetate, ethyl acetate, methyl propionate, ethyl propionate,
1,2-dichloroethane, .gamma.-butyrolactone, .gamma.-valerolactone,
dimethoxyethane, diethoxyethane, methyl formate, dimethyl
carbonate, methyl ethyl carbonate, diethyl carbonate, dipropyl
carbonate, methylpropyl carbonate, ethylene carbonate, propylene
carbonate, vinylene carbonate, butylene carbonate, dimethyl
formamide, dimethyl sulfoxide, dimethyl formamide, sulfolane,
3-methyl sulfolane, trimethyl phosphate, triethyl phosphate, and
phosphazene derivatives and mixed solvents thereof. Among these,
ethylene carbonate, propylene carbonate, 7-butyrolactone, dimethyl
carbonate, methyl ethyl carbonate, and diethyl carbonate can be
used alone or in combination with two or more.
[0080] As a solute for the electrolyte to be used in the present
invention, a variety of solutes are usable accordingly without
special limitation. For example, the following can be used alone or
in combination with two or more: LiClO.sub.4, LiBF.sub.4,
LiAsF.sub.6, LiPF.sub.6, LiCF(CF.sub.3).sub.5,
LiCF.sub.2(CF.sub.3).sub.4, LiCF.sub.5(CF.sub.3).sub.2,
LiCF.sub.4(CF.sub.3).sub.2, LiCF.sub.5(CF.sub.3),
LiCF.sub.5(C.sub.2F.sub.6).sub.3, LiCF.sub.3SO.sub.3,
LiN(CF.sub.3SO.sub.2).sub.2, LiN(C.sub.2F.sub.5SO.sub.2).sub.2,
LiN(C.sub.2F.sub.5CO).sub.2, Li, LiAlCl.sub.4, and
LiBC.sub.4O.sub.8. Among them, the use of LiPF.sub.6 is preferred.
Moreover, it is preferable that their lithium salt concentrations
be 0.5 to 2.0 mol dm.sup.-3.
[0081] Furthermore, at least one material selected from the group
consisting of the following may be contained in the electrolyte to
be used: carbonates such as vinylene carbonate and butylene
carbonate; benzenes such as biphenyl and cyclohexylbenzen; sulfurs
such as propane sultone; ethylenesulfide, hydrogen fluoride and
triazole cyclic compounds; fluorine-containing esters; hydrogen
fluoride complexes of tetraethylammonium fluoride or derivatives
thereof; phosphazene and the derivatives; amido group-containing
compounds; imino group-containing compounds; or nitrogen-containing
compounds. It is also possible to use the electrolyte which
contains at least one of the following: CO.sub.2, NO.sub.2, CO, or
SO.sub.2.
[0082] As a separator to be used in the present invention, a
variety of materials are usable accordingly without special
limitation. There are for example, woven fabric, nonwoven fabric,
and synthetic-resin microporous membrane; among them,
synthetic-resin microporous membrane is preferred. Concerning the
material for the synthetic-resin microporous membrane, it is
possible to use nylon, cellulose acetate, nitrocellulose,
polysulfone, polyacrylonitrile; poly(vinylidene fluoride), and
pollyolefins such as polyethylene, polypropylene, and polybutene;
among them, in the light of the thickness, strength, and resistance
of membrane, the microporous membrane made of polyethylene or
polypropylene, or the polyolefin microporous membrane such as
polyethylene-polypropylene composite microporous membrane is
preferred. It is also possible to use a separator which is
configured by laminating several sheets of microporous membrane
different in material, weight average molecular weight, or
porosity; or by adding an appropriate amount of additives of
various kinds such as plasticizers, antioxidants, and flame
retardants to such microporous membrane.
[0083] For the above described electrolyte, furthermore, an
ion-conducting electrolyte of a solid or gel state can be used
either alone or in combination. In case of using it in combination,
a non-aqueous electrolyte secondary battery is configured with a
positive electrode, a negative electrode, and a combination of a
separator, an organic or inorganic solid electrolyte, and the
above-described non-aqueous electrolyte solution; or with a
positive electrode, a negative electrode, and a combination of an
organic or inorganic solid electrolyte membrane, as a separator,
and the above-described non-aqueous electrolyte solution. It is
also possible to use porous polymer electrolyte membrane of a solid
state for an ion-conducting electrolyte. And for an ion-conducting
electrolyte, the following can be used: polyethylene oxide,
polypropylene oxide, polyacrylonitrile, polyethylene glycol, and
derivatives thereof; and thio-licicon typified by LiI, Li.sub.3N,
Li.sub.1+XM.sub.XTi.sub.2-X(PO.sub.4).sub.3 (where M=Al, Sc, Y, and
La), Li.sub.0.5-3XR.sub.0.5+XTiO.sub.3 (where R=La, Pr, Nd, and
Sm), or Li.sub.4-XGe.sub.1-XP.sub.XS.sub.4. It is also possible to
use oxide glass such as LiI--Li.sub.2O--B.sub.2O.sub.5 or
Li.sub.2O--SiO.sub.2, or sulfide glass such as
LiI--Li.sub.2S--B.sub.2S.sub.3, LiI--Li.sub.2S--SiS.sub.2, or
Li.sub.2S--SiS.sub.2--Li.sub.3PO.sub.4.
[0084] Furthermore, there is no special limitation on a form of
battery; the present invention is applicable to non-aqueous
electrolyte secondary batteries of various forms including
prismatic, elliptic, cylindrical, coin, button, and sheet type
batteries.
Embodiment A
Embodiment A1
[0085] Lithium cobalt oxide was used as a positive active material
in the preparation of a non-aqueous electrolyte secondary battery
of a prismatic type. FIG. 2 shows the cross sectional configuration
of a non-aqueous electrolyte secondary battery of a prismatic type.
In FIG. 2, the non-aqueous electrolyte secondary battery of a
prismatic type is expressed as 41, winding-type electrodes as 42,
an positive electrode as 43, a negative electrode as 44, a
separator as 45, a battery case as 46, a battery cap as 47, a
safety valve as 48, a positive terminal as 49, and a positive lead
as 50.
[0086] The winding-type electrodes 42 is housed in the battery case
46, the battery case 46 is equipped with the safety valve 48, and
the battery cap 47 and the battery case 46 are sealed up by means
of laser welding. The positive terminal 49 is connected with the
positive electrode 43 with the positive lead 50, and the negative
electrode 44 is connected to the inner wall of the battery case 46
in direct contact.
[0087] The positive electrode was prepared according to the
following manner. 90 wt. % of LiCoO.sub.2 as an active material, 5
wt. % of acetylene black as a conductive material, and 5 wt. % of
poly(vinylidene fluoride) as a binder were mixed together to form a
positive composite, and this composite was dispersed in
N-methyl-2-pyrrolidone to make a positive paste. The obtained
positive paste was uniformly applied to an aluminum current
collector having a thickness of 20 .mu.m, and after dried, the
obtained material was compressed and molded by roll pressing to
prepare the positive electrode.
[0088] The negative electrode was prepared according to the
following manner. The surface of Si particle was coated with carbon
material by means of CVD method, and composite particle was
prepared (which corresponds to the composite particle in the
present invention, and hereinafter referred to as the composite
particle (C)). The composite particle (C), which was configured so
that the coating amount of the carbon material was 20 wt. %, was
mixed with natural graphite (d002 of 0.3359 nm, and BET specific
surface area of 7.4 cm.sup.2/g), as carbon material (which
corresponds to the carbon material in the present invention, and
hereinafter referred to as the carbon material (D)), in a weight
ratio of 80:20 to prepare a negative active material. 90 wt. % of
the obtained negative active material and 10 wt. % of carboxy
poly(vinylidene fluoride) as a binder were mixed together to form a
negative composite, and this composite was dispersed in
N-methyl-2-pyrrolidone to make a negative paste.
[0089] The above-obtained negative paste was uniformly applied to a
copper foil having a thickness of 15 .mu.m, and after dried at
100.degree. C. for 5 hours, this material was compressed and molded
by roll pressing to prepare the negative electrode.
[0090] For the separator, a polyethylene microporous membrane
having a thickness of approximately 25 .mu.m was used.
[0091] An electrolyte solution was prepared as follows: ethylene
carbonate and diethyl carbonate were mixed together in a volume
ratio of 1:1, and then 1.0 M of LiPF.sub.6 was dissolved in the
obtained mixture.
Embodiments A2 to A5, and Comparative Example A1
[0092] In these batteries, the following weight percentages were
used as the amount of carbon coating in the composite particle (C):
0, 5, 40, 60, and 70 wt. %. Except for the above, the batteries
have an identical configuration to that of Embodiment A1.
[0093] These non-aqueous electrolyte secondary batteries were
charged at a constant current of 1 CmA and a constant voltage of
3.9 V at a temperature of 25.degree. C. for 3 hours and made to
reach a fully charged state. Subsequently, they were discharged at
a current of 1 CmA until the voltages dropped to 2.45 V. These
steps were taken as one cycle and the obtained discharge capacity
was considered as the initial discharge capacity. After that, under
the same conditions as the above, a total of 100 charge/discharge
cycles were carried out, and the discharge capacity at the 1st
cycle and a change in discharge capacity with an increase in the
number of cycle times (capacity retention ratio according to cycle)
were determined. The results are shown in Table A1.
TABLE-US-00001 TABLE A1 Proportion of the Amount of carbon
Proportion of the Capacity composite particle (C) coating in carbon
material (D) retention ratio in the negative the composite in the
negative according to Discharge active material particle (C) active
material cycle capacity (wt. %) (wt. %) (wt. %) (%) (mAh) EM A1 80
20 20 90 640 EM A2 80 5.0 20 89 650 EM A3 80 40 20 93 630 EM A4 80
60 20 94 590 CE A1 80 0 20 34 670 EM A5 80 70 20 67 560
[0094] In Tables A1 to A4, EM in the first column refers to
Embodiment and CE refers to Comparative Example; for example, EM A1
refers to Embodiment A1 and CE A1 refers to Comparative Example
A1.
Here, the capacity retention ratio according to cycle means the
percentage (%) obtained by dividing the discharge capacity at the
100th cycle by the one at the 1.sup.st cycle.
[0095] As shown in the results of Embodiments A1 to A5 and
Comparative Example A1, the batteries in which carbon coating was
applied in the composite particle (C) are superior in the cycle
performance, although the one in which the amount of carbon coating
exceeds 70 wt. % shows a deterioration in the cycle performance;
therefore, it is found that the preferable amount of carbon coating
is not greater than 60 wt. %. In addition, since initial discharge
capacities decrease significantly when the amount of carbon coating
exceeds 40 wt. %, it is also clear that the more preferable amount
of carbon coating is not greater than 40 wt. %.
Embodiments A6 to A9
[0096] In these batteries, the following distances were used as the
average interplanar spacing d (002) of the carbon to be used for
coating in the composite particle (C): 0.3354 nm, 0.3482 nm, 0.3510
nm, and 0.370 nm. Except for the above, the batteries have an
identical configuration to that of Embodiment A1.
[0097] In the same manner as the above, the discharge capacity at
the 1.sup.st cycle and a change in discharge capacity with an
increase in the number of cycle times (capacity retention ratio
according to cycle) were determined. The results are shown in Table
A2.
TABLE-US-00002 TABLE A2 Capacity retention ratio according
Discharge d(002) to cycle capacity (nm) (%) (mAh) EM A1 0.3359 90
640 EM A6 0.3354 89 650 EM A7 0.3482 81 638 EM A8 0.3510 74 635 EM
A9 0.370 70 630
[0098] As shown in the results of the capacity retention ratios of
Embodiments A1, and A6 to A9, it is preferable that the average
interplanar spacing d (002) of the carbon for coating be not
greater than 0.35 nm. It is believed that when the average
interplanar spacing is greater than 0.35 nm, the contact
conductivity between the active material and between the active
material and the current collector decreases, so that the cycle
performance deteriorates.
Embodiments A10 to A14
[0099] In these batteries, the following areas were used as the BET
specific surface area of the composite particle (C): 1.0 m.sup.2/g,
6.3 m.sup.2/g, 10 m.sup.2/g, 0.5 m.sup.2/g, and 11.0 m.sup.2/g.
Except for the above, the batteries have an identical configuration
to that of Embodiment A1.
[0100] In the same manner as the above, the discharge capacity at
the 1.sup.st cycle and a change in discharge capacity with an
increase in the number of cycle times (capacity retention ratio
according to cycle) were determined. The results are shown in Table
A3.
TABLE-US-00003 TABLE A3 Capacity retention BET specific ratio
according Discharge surface area to cycle capacity (m.sup.2/g) (%)
(mAh) EM A1 7.4 90 640 EM A10 1.0 85 635 EM A11 6.3 81 638 EM A12
10.0 84 620 EM A13 0.5 62 630 EM A14 11.0 79 590
[0101] These results reveal that when the BET specific surface area
of the composite particle (C) falls within the range of 1.0 to 10.0
m.sup.2/g, satisfactory cycle performance is achieved. It is
believed that when the BET specific surface area is less than 1.0
m.sup.2/g, the current density per surface area of the active
material during charge/discharge becomes large; therefore, Li is
deposited on the negative electrode and consequently the cycle
performance deteriorates. On the other hand, it is believed that
when it exceeds 10 m.sup.2/g, the reaction area with the
electrolyte solution during charge becomes large and the
decomposition of the electrolyte solution is made to proceed, so
that the cycle performance deteriorates. In addition, it is shown
that when it exceeds 10 m.sup.2/g, the discharge capacity
deteriorates; thus, it is preferable to employ the BET specific
surface area of not larger than 10 m.sup.2/g.
Embodiments A15 to A17, and Comparative Example A2
[0102] In these batteries, the following weight ratios were used as
the mixture ratio of the composite particle (C) to the carbon
material (D): 99.5:0.5, 60:40, 50:50, and 100:0. Except for the
above, the batteries have an identical configuration to that of
Embodiment A1.
[0103] In the same manner as the above, the discharge capacity at
the 1st cycle and a change in discharge capacity with an increase
in the number of cycle times (capacity retention ratio according to
cycle) were determined. The results are shown in Table A4.
TABLE-US-00004 TABLE A4 Proportion of the Proportion of the
composite particle (C) carbon material (D) Capacity retention in
the negative in the negative ratio according Discharge active
material active material to cycle capacity (wt. %) (wt. %) (%)
(mAh) EM A1 80 20 90 640 EM A15 99.5 0.5 85 650 EM A16 60 40 94 630
EM A17 50 50 95 580 CE A2 100 0 72 660
[0104] These results reveal that utilizing the carbon material (D)
results in improvement in the capacity retention ratio according to
cycle. It is believed that the reason for this may be that the
contact conductivity between the active material and between the
active material and the current collector deteriorates.
Furthermore, it is shown that when the proportion of the carbon
material (D) to the total weight of the composite particle (C) and
the carbon material (D) lies in the range of 0.5 to 40 wt. %, a
battery having a large initial discharge capacity and satisfactory
cycle performance can be provided.
Embodiment B
Embodiment B1
[0105] Lithium cobalt oxide was used as a positive active material
in the preparation of a non-aqueous electrolyte secondary battery
of a prismatic type. FIG. 3 shows the cross sectional configuration
of a non-aqueous electrolyte secondary battery of a prismatic type.
In FIG. 3, the non-aqueous electrolyte secondary battery of a
prismatic type is expressed as 21, winding-type electrodes as 22,
an positive electrode as 23, a negative electrode as 24, a
separator as 25, a battery case as 26, a battery cap as 27, a
safety valve as 28, a negative terminal as 29, a positive lead as
30, and a negative lead as 31.
[0106] The winding-type electrodes 22 is housed in the battery case
26, and the battery cap 27 and the battery case 26 are sealed up by
means of laser welding. The battery cap 27 is equipped with the
safety valve 28. The negative terminal 29 is connected with the
negative electrode 24 with the negative lead 31, and the positive
electrode 23 is connected to the inner wall of the battery case 26
in direct contact and to the battery cap 27 with the positive lead
30.
[0107] A positive electrode plate was prepared according to the
following manner. 90 wt. % of LiCoO.sub.2 as an active material, 5
wt. % of acetylene black as a conductive material, and 5 wt. % of
poly(vinylidene fluoride) as a binder were mixed together to form a
positive composite, and this composite was dispersed in
N-methyl-2-pyrrolidone to make a positive paste. The obtained
positive paste was uniformly applied to an aluminum current
collector having a thickness of 20 .mu.m, and after dried, this
material was compressed and molded by roll pressing to prepare the
positive electrode plate. The dimensions of the positive electrode
plate were 160 .mu.m in thickness, 18 mm in width, and 600 mm in
length.
[0108] A negative active material was prepared according to the
following manner. As silicon material, 400 g of carbon powder
(average particle size of 9 .mu.m, specific surface area of 4
m.sup.2/g, and average interplanar spacing d002 of 0.3360 nm) were
added to 500 g of silicon powder (purity of 99% and average
particle size of 5 .mu.m), these powders were mixed and ground in a
ball mill for 60 minutes, and then granulated bodies of silicon and
carbon were prepared. 500 g of such granulated particle was put
into a stainless steel container, a nitrogen atmosphere was created
entirely in the stainless steel container while the container was
agitated, the internal temperature was then raised up to
1000.degree. C., subsequently benzene vapor was introduced in said
stainless steel container, and CVD process was executed for 120
minutes. After that, the temperature was lowered down to the room
temperature under nitrogen atmosphere, and the negative active
material was obtained.
[0109] On the obtained negative active material, TG measurement was
conducted, and in a temperature rise at a rate of 10.+-.2.degree.
C./min, the following two stages of weight loss were observed: at
the first stage, the temperature at which weight loss started
(hereinafter referred to as T1) was 570.degree. C. and the amount
of weight loss (hereinafter referred to as W1) was 15 wt. %; and at
the second stage, the temperature at which weight loss started
(hereinafter referred as to T2) was 700.degree. C. and the amount
of weight loss (hereinafter referred as to W2) was 30 wt. %.
[0110] A negative electrode plate was prepared according to the
following manner. 90 wt. % of the above-described negative active
material and 10 wt. % of carboxy poly(vinylidene fluoride) as a
binder were mixed together to form a negative composite, the
obtained composite was dispersed in N-methyl-2-pyrrolidone to make
a negative paste, the obtained paste was uniformly applied to a
copper foil having a thickness of 15 .mu.m, and after dried at
100.degree. C. for 5 hours, this material was compressed and molded
by roll pressing to prepare the negative electrode. The dimensions
of the negative electrode plate were 180 .mu.m in thickness, 19 mm
in width, and 630 mm in length.
[0111] For the separator, a polyethylene microporous membrane
having a thickness of 20 .mu.m was used. An electrolyte solution
was prepared as follows: ethylene carbonate and diethyl carbonate
were mixed together in a volume ratio of 1:1, and 1.0 M of
LiPF.sub.6 was dissolved in the obtained mixture.
[0112] And, a winding-type power generating element was configured
as follows: the positive and negative electrode plates were
overlapped each other with the separator therebetween, and spirally
wound in an elliptic shape around a polyethylene core as a center.
This winding-type power generating element was then housed in the
iron battery case of a prismatic type, the battery case was filled
with the electrolyte solution, the filling port was sealed, and
thus the battery was prepared. The dimensions of the battery were
47 mm in length, 23 mm in width, and 8 mm in thickness, and the
rated capacity was 600 mAh. This battery was termed Battery A.
[0113] This non-aqueous electrolyte secondary battery was charged
at a constant current of 600 mA at a temperature of 25.degree. C.,
at first until the voltage reached 4.2 V and, when reached, at a
constant voltage of 4.2 V, for a total of 3 hours, and made to
reach a fully charged state. Subsequently, the battery was
discharged at a constant current of 600 mA until the voltage
dropped to 2.45 V. These steps were taken as one cycle and the
obtained discharge capacity was considered as the initial discharge
capacity. After that, under the same conditions as the above, a
total of 100 charge/discharge cycles were carried out, and the
discharge capacity at the 1.sup.st cycle (initial discharge
capacity), the thickness of battery at the 1.sup.st
charge/discharge cycle, and a change in discharge capacity with an
increase in the number of charge/discharge cycles were determined.
Here, the percentage (%) of the discharge capacity at the
100.sup.th cycle to the one at the 1.sup.st cycle refers to
"capacity retention ratio."
[0114] Except for using the negative active materials which differ
in the number of the stages at which weight loss appeared, the
temperature at which weight loss started, and the amount of weight
loss in the TG measurement conducted at a temperature rising rate
of 10-2.degree. C./min, the batteries listed in Table B2 have an
identical configuration to that of Embodiment B1. The producing
conditions used for each battery are listed in Table B3.
[0115] The carbon material for each Embodiment and Comparative
Example was prepared in the following manner. A given amount of
carbon powder feeding, listed in Table B1, was added to 500 g of
silicon powder; these powders were milled in a ball mill for a
given period of time, listed in Table B1, to prepare granulated
bodies; 500 g of such granulated particle was then put into a
stainless steel container; the internal temperature was raised up
to a given temperature for CVD process, listed in Table B1; benzene
vapor was introduced; and CVD process was performed for a given
period of time, listed in Table B1.
TABLE-US-00005 TABLE B1 Temperature Time for Time for Bat- for CVD
CVD process ball milling Amount of tery process .degree. C. min.
min. feeding g EM B1 A 1000 120 60 400 EM B2 B 800 120 60 400 EM B3
C 1050 120 60 400 EM B4 D 1000 120 120 400 EM B5 E 1000 120 40 400
EM B6 F 780 120 60 400 EM B7 G 1000 120 30 400 EM B8 H 1000 40 60
400 EM B9 I 1000 200 60 400 EM B10 J 1000 120 60 130 EM B11 K 1000
120 60 800 EM B12 L 1000 120 60 400 CM B1 M -- -- -- -- CE B2 N
1000 120 -- -- CE B3 O 1200 120 -- -- EM B13 P 1100 120 60 400 EM
B14 Q 1000 120 140 400 EM B15 R 1000 8 60 400 EM B16 S 1000 320 60
400 EM B17 T 1000 120 60 40 EM B18 U 1000 120 60 930
[0116] In Tables B1 to B8, EM in the first column refers to
embodiment an C refers to Comparative Example; for example, EM B1
refers to Embodiment B1 and CE B1 refers to Comparative Example
B1.
TABLE-US-00006 TABLE B2 Number of stages Temperature at Amount of
at which weight which weight weight loss appeared in loss started
.degree. C. loss % Battery TG measurement T1 T2 W1 W2 EM B1 A 2 570
700 15 30 EM B2 B 2 370 700 15 30 EM B3 C 2 590 700 15 30 EM B4 D 2
570 620 15 30 EM B5 E 2 570 780 15 30 EM B6 F 2 340 700 15 30 EM B7
G 2 570 810 15 30 EM B8 H 2 570 700 5 30 EM B9 I 2 570 700 25 30 EM
B10 J 2 570 700 15 10 EM B11 K 2 570 700 15 60 EM B12 L 2 570 700
15 30 CE B1 M 0 -- -- -- -- CE B2 N 1 570 -- 15 -- CE B3 O 1 650 --
15 -- EM B13 P 2 620 700 15 30 EM B14 Q 2 570 580 15 30 EM B15 R 2
570 700 1 30 EM B16 S 2 570 700 40 30 EM B17 T 2 570 700 15 3 EM
B18 U 2 570 700 15 70
TABLE-US-00007 TABLE B3 Capacity Initial discharge Battery
thickness retention Battery capacity mAh during charge mm ratio %
EM B1 A 650 6.10 90 EM B2 B 650 6.15 89 EM B3 C 650 6.10 88 EM B4 D
650 6.10 86 EM B5 E 650 6.15 90 EM B6 F 640 6.20 68 EM B7 G 640
6.20 72 EM B8 H 660 6.15 85 EM B9 I 645 6.10 90 EM B10 J 665 6.10
86 EM B11 K 635 6.10 91 EM B12 L 628 6.10 96 CE B1 M 630 6.50 20 CE
B2 N 630 6.25 40 CE B3 O 670 6.30 50 EM B13 P 650 6.30 63 EM B14 Q
640 6.30 61 EM B15 R 660 6.30 52 EM B16 S 625 6.10 56 EM B17 T 665
6.30 38 EM B18 U 605 6.10 53
[0117] The evaluation results for these batteries are shown in
Table B3.
[0118] These results reveal the following findings. In the
batteries having the negative active material which exhibits
two-stage weight loss, the thickness of the batteries during charge
is small and the charge/discharge cycle performance is
satisfactory. On the other hand, in the battery having the negative
active material which exhibits no weight loss, the thickness of the
battery during charge is large and the charge/discharge cycle
performance is unsatisfactory. In addition, in the batteries having
the negative active material which exhibits one-stage weight loss,
the charge/discharge cycle performance is unsatisfactory. Moreover,
those having the negative active material in which T1 is not higher
than 600.degree. C. and T2 is not lower than 600.degree. C. show
extremely excellent charge/discharge cycle performance.
[0119] Furthermore, in the batteries having the negative active
material in which W1 and W2 fall within the ranges of 3 to 30 wt. %
and 5 to 65 wt. %, respectively, to the weight prior to the
temperature rise in TG measurement, it is found that the swelling
of the batteries is not significant and extremely excellent
charge/discharge cycle performance is exhibited. In addition, in
Battery L having the negative active material which was prepared
using a mixture of carbon and silicon-carbon composite, although
the initial discharge capacity is a little inferior to that of
Battery A, the capacity retention ratio stands at 96% and therefore
further improvement in charge/discharge cycle performance was able
to be confirmed.
Embodiment C
[0120] FIGS. 4 to 7 show schematic views of the composite particle
described in claim 6. FIG. 4 is a schematic view illustrating the
composite particle 10, which is composed of the particle 11
consisting of Si, the particle 12 consisting of SiO.sub.x (where
0<X.ltoreq.2), and the carbon material A13.
[0121] The above composite particle 10 can be obtained by milling
the particle 11 consisting of Si, the particle 12 consisting of
SiO.sub.x, and the carbon material A13 with the use of a milling
machine. Such a milling process can be carried out in the air;
however, an inert atmosphere such as argon or nitrogen is
preferred. There are following types of milling process: ball mill,
vibration mill, satellite ball mill, tube mill, jet mill, rod mill,
hammer mill, roller mill, disc mill, attritor mill, planetary ball
mill, and impact mill. It is also possible to use mechanical
alloying method. The applicable range of milling temperature is
from 10.degree. C. to 300.degree. C.; and that of milling time is
from 30 seconds to 48 hours.
[0122] FIG. 5 is a schematic view illustrating the composite
particle, which is configured by coating the surface of the
above-described composite particle 10 with the carbon material B14.
FIG. 6 is a schematic view illustrating the composite particle 16,
which is composed of the particle 15 containing Si and SiO.sub.x
(where 0<X.ltoreq.2) and the carbon material A13. Such composite
particle 16 can be obtained according to the preparation procedures
identical to those of the composite particle 10, by using the
particle 15 containing Si and SiO.sub.x and the carbon material
A13. FIG. 7 is a schematic view illustrating the composite
particle, which is configured by coating the surface of the
above-described composite particle 16 with the carbon material
B14.
[0123] In order to coat the surface of the composite particle 10 or
16 with the carbon material B14, the following methods can be used:
coating the surface of the composite particle 10 or 16 with an
organic compound and then performing calcination; or utilizing
chemical vapor deposition (CVD) technique.
[0124] In CVD method, it is possible to use organic compounds such
as methane, acetylene, benzene, toluene, etc. as a reaction gas.
The applicable reaction temperature and time, respectively, range
from 700.degree. C. to 1300.degree. C. and from 30 seconds to 72
hours. Using CVD method, coating treatment with carbon material can
be implemented at a lower reaction temperature, in comparison with
the method of calcinating an organic compound on the surface.
Therefore, CVD method is preferred in that the coating treatment
can be performed at a temperature not higher than the respective
melting points of the particle 11 consisting of Si, the particle 12
consisting of SiO.sub.x, and the particle 15 containing Si and
SiO.sub.x.
[0125] By performing Raman spectroscopic analysis, it is possible
to determine whether or not the surface of the composite particle
10 is coated with the carbon material B14. Since the surface area
of a sample is analyzed by Raman spectroscopic analysis, if the
surface of the composite particle 10 is entirely coated with the
carbon material B14, R value (intensity ratio of a peak intensity
of 1360 cm.sup.-1 to a peak intensity of 1580 cm.sup.-1), which
indicates the crystalline quality of the carbon material B14 on the
surface, should stand at a constant value wherever measurement is
taken on the particle of the negative active material. For
conducting Raman spectroscopic analysis, it is possible to use, for
example, a spectrometer T64000 (JOBIN YVON).
[0126] Regarding the particle consisting of Si, the particle
consisting of SiO.sub.x (where 0<X.ltoreq.2), or the particle
containing Si and SiOx (where 0<X.ltoreq.2), the following can
also be used: the particles which have been washed with such acid
as fluorinated acid or sulfuric acid, or the particles which have
been reduced with hydrogen.
[0127] The proportions of the carbon material A13 and the carbon
material B14 to the entire negative active material can be
determined by means of thermogravimetry. For example, in
thermogravimetry at a temperature rising rate of 10.+-.2.degree.
C./min, the carbon material A13 and the carbon material B14 are
observed to exhibit weight loss in a temperature range of
30.degree. C. to 1000.degree. C. In the vicinity of 580.degree. C.,
the carbon material B14 of relatively low crystalline on the
surface of the composite particle 10 is observed to exhibit weight
loss, and next in the vicinity of 610.degree. C., the carbon
material A13 which was milled together with the particle 11
consisting of Si, the particle 12 consisting of SiO.sub.x, and the
particle 15 containing Si and SiO.sub.x, is observed to exhibit
weight loss. The particle 11 consisting of Si, the particle 12
consisting of SiO.sub.x, and the particle 15 containing Si and
SiO.sub.x are observed to exhibit weight loss in a range of around
1500.degree. C. to 2000.degree. C. Based on these results, the
weight ratio of each material can be determined.
[0128] As a device for such thermogravimetry, it is possible to
use, for example, SSC/5200 (Seiko Instruments Inc.). The specific
surface area of the negative active material can be determined by
low-temperature gas adsorption technique, according to dynamic
constant pressure method at a range of pressure measurement from 0
to 126.6 KPa, using, for example, a micromeritics analyzer
GEMINI2370 (SHIMADZU) with the use of liquid nitrogen, and analyzed
by means of BET method. And as data processing software, GEMINI-PC1
can be used.
Embodiment C1
[0129] As a negative active material, composite particle was
prepared by treating 30 parts by weight of Si, 30 parts by weight
of SiO.sub.2, and 40 parts by weight of artificial graphite under
nitrogen atmosphere by ball milling at 25.degree. C. for 30
minutes.
[0130] 95 wt. % of the above-obtained negative active material, 3
wt. % of SBR, and 2 wt. % of CMC were mixed in water to prepare a
negative paste. The obtained negative paste was applied to a copper
foil having a thickness of 15 .mu.m so that the weight of the
coating could be 1.15 mg/cm.sup.2 and the quantity of the negative
active material to be housed in the battery could be 2 g, and then
dried at 150.degree. C. to evaporate water. This process was
performed on both sides of the copper foil, which then compressed
and molded by roll pressing. Thus, a negative electrode plate both
sides of which were coated with the negative composite layer was
prepared.
[0131] 90 wt. % of lithium cobalt oxide as a positive active
material, 5 wt. % of acetylene black as a conductive material, and
5 wt. % of PVDF as a binder were dispersed in NMP to make a
positive paste. The obtained positive paste was applied to an
aluminum foil having a thickness of 20 .mu.m so that the weight of
the coating could be 2.5 mg/cm.sup.2 and the quantity of the
positive active material to be housed in the battery could be 5.3
g, and then dried at 150.degree. C. to evaporate NMP. The
above-described process was performed on both sides of the aluminum
foil, which then compressed and molded by roll pressing. Thus, a
positive electrode plate both sides of which were coated with the
positive composite layer was prepared.
[0132] A winding-type power generating element was made by
overlapping and winding the positive and negative electrode plates
thus prepared with a polyethylene separator, with continuous
porosity having a thickness of 20 .mu.m and a porosity of 40%,
being placed between them. This winding-type power generating
element was housed in the case having 48 mm in height, 30 mm in
width, and 4.2 mm in thickness, the case was then filled with a
non-aqueous electrolyte solution, and thus a non-aqueous
electrolyte secondary battery of a prismatic type was prepared. The
used non-aqueous electrolyte solution was prepared as follows:
ethylene carbonate (EC) and diethyl carbonate (DEC) were mixed
together in a volume ratio of 1:1, and 1 mol/l of LiPF.sub.6 was
dissolved in the mixed solvent thus prepared.
Embodiment C2
[0133] In Embodiment C2, a negative active material was prepared as
follows: composite particle was prepared by treating 20 parts by
weight of Si, 20 parts by weight of SiO.sub.2, and 40 parts by
weight of artificial graphite under nitrogen atmosphere by ball
milling at 25.degree. C. for 30 minutes, and after that, by means
of the method (CVD) of thermally decomposing methane at 900.degree.
C., the surface of the composite particle was coated with carbon
material. Except for using the negative active material thus
prepared, the non-aqueous electrolyte secondary battery has an
identical configuration to that of Embodiment C1.
Embodiment C3
[0134] In Embodiment C3, SiO was used in stead of SiO.sub.2. Except
for the above, the non-aqueous electrolyte secondary battery has an
identical configuration to that of Embodiment C2
Comparative Examples C1 to C4
[0135] In Comparative Examples C1 to C4, those listed in Table C1
were employed. Except for the above, the non-aqueous electrolyte
secondary batteries have an identical configuration to that of
Embodiment C2.
<Measurement>
Raman Spectroscopic Analysis
[0136] On each negative active material prepared as above, Raman
spectroscopic analysis was conducted according to the
above-described manner to determine an R value. The R value was
found to be approximately 0.8 in any measurement point on the
particle of the negative active material. This R value will stand
at 0 when the sample is highly crystalline, and as the crystalline
quality becomes lower, the value will become larger. Because of the
value being approximately 0.8, this particle was confirmed to be
uniformly coated with the carbon material of relatively low
crystalline which was deposited by means of CVD method.
[0137] (Thermogravimetry)
[0138] On eachnegative active material prepared as above,
thermogravimetry was employed according to the above-described
manner, and the weight ratio of each material was determined.
[0139] (XRD)
[0140] On each negative active material prepared as above, X-ray
diffraction was performed according to the above-described manner,
and the average interplanar spacing d(002) of the carbon material
was determined from the diffraction angle (2 .theta.) in the X-ray
diffraction pattern with CuK.alpha. radiation.
[0141] (BET Specific Surface Area)
[0142] For each negative active material prepared as above, BET
specific surface area was determined according to the
above-described manner.
[0143] (Charge/Discharge Performance)
[0144] Each non-aqueous electrolyte secondary battery prepared as
above was charged at a current of 1 CmA at a temperature of
25.degree. C. until the voltage reached 4.2 V, subsequently charged
at a constant voltage of 4.2 V for 2 hours, and then discharged at
a current of 1 CmA until the voltage dropped to 2.0 V. These steps
were taken as one cycle and the charge/discharge test was repeated
500 cycles. The ratio (expressed in percentage) of the discharge
capacity at the 500.sup.th cycle to the one at the 1.sup.st cycle
referred to the capacity retention ratio according to cycle.
[0145] <Results>
[0146] The results of measurement were summarized in Table C1.
[0147] In Embodiments C1 to C3, the capacity retention ratios are
higher than that of Comparative Example C1, where SiO.sub.x is not
contained, and the discharge capacities are larger than that of
Comparative Example C2, where Si is not contained. In addition, the
capacity retention ratios are higher than that of Comparative
Example C3, where carbon material is not contained in the composite
particle, and the discharge capacities are larger than that of
Comparative Example C4, where Si and SiO.sub.x are not
contained.
[0148] Embodiments C2 and C3, where the particle (A) is coated with
carbon, are superior in the capacity retention ratios, compared to
Embodiment C1.
Embodiments C4 to C8
[0149] In Embodiments C4 to C8, as the proportions of the weight of
Si to the total weight of Si and SiO.sub.2, those listed in Table
C2 were used. Except for the above, the non-aqueous electrolyte
secondary batteries have an identical configuration to that of
Embodiment C2. In addition, various measurement results regarding
these embodiments were summarized in Table C2.
[0150] The batteries where the proportions of the weight of the
particle consisting of Si to the total weight of the particle
consisting of Si and the particle consisting of SiO.sub.x fall
within the range of 20 wt. % to 80 wt. % have larger discharge
capacities compared to the battery where the proportion of the
weight of the particle consisting of Si stands at 10 wt. %.
Embodiments C9 to C14
[0151] In Embodiments C9 to C14, as the proportions of the additive
amount of the artificial graphite which is mixed together with Si
and SiO.sub.2, those listed in Table C3 were used. Except for the
above, the non-aqueous electrolyte secondary batteries have an
identical configuration to that of Embodiment C2. Various
measurement results regarding these embodiments were summarized in
Table C3.
[0152] The batteries where the proportions of the artificial
graphite to the entire negative active material fall within the
range of 3 wt. % to 60 wt. % have higher capacity retention ratios
compared to the battery where the proportion of the artificial
graphite stands at 1 wt. %. On the other hand, those batteries have
larger discharge capacities compared to the battery where the
proportion of the artificial graphite stands at 70 wt. %.
[0153] The batteries where the proportions of the total carbon
material to the entire negative active material fall-within the
range of 30 wt. % to 80 wt. % have higher capacity retention ratios
compared to the batteries where the proportions of the total carbon
material stand at 21 wt. % and 23 wt. %, respectively. In addition,
the former batteries have larger discharge capacities and higher
capacity retention ratios compared to the battery where the
proportion of the total carbon material stands at 90 wt. %.
Embodiments C15 to C17
[0154] As the carbon material which is mixed together with Si and
SiO.sub.2, natural graphite, acetylene black, and vapor grown
carbon fiber were used in Embodiments C15, C16, and C17,
respectively, instead of artificial graphite. Except for the above,
the non-aqueous electrolyte secondary batteries have an identical
configuration to that of Embodiment C2. Various measurement results
regarding these embodiments as well as those of Embodiment C2 were
summarized in Table C4.
[0155] Embodiments C2, C15, and C17, where the average interplanar
spacing d(002) fall within the range of 0.3354 nm to 0.35 nm, have
larger discharge capacities and higher capacity retention ratios
compared to Embodiment C16, where d(002) is 0.37 nm.
Embodiments C18 to C20
[0156] In Embodiments C18 to C20, as the amounts of the carbon with
which the surface of the composite particle was coated, those
listed in Table C5 were employed to prepare negative active
materials. Those values were obtained by appropriately varying the
reaction conditions in the coating treatment with carbon material
by means of CVD method. Except for the above, the non-aqueous
electrolyte secondary batteries have an identical configuration to
that of Embodiment C2.
[0157] Various measurement results regarding these embodiments as
well as those of Embodiment C2 were summarized in Table C5.
[0158] Embodiments C2, C18, and C19, where the proportions of the
carbon material on the surface of the composite particle to the
entire negative active material fall within the range of 0.5 wt. %
to 40 wt. %, have larger discharge capacities and higher capacity
retention ratios compared to Embodiment C20, where the proportion
of the carbon material is 50 wt. %.
Embodiments C21 to C23
[0159] In Embodiments C21 to C23, the negative active materials
were prepared employing the BET specific surface areas listed in
Table C6. Those surface areas were obtained by using the Si,
SiO.sub.2, and artificial graphite which have predetermined
specific surface areas. Except for the above, the non-aqueous
electrolyte secondary batteries have an identical configuration to
that of Embodiment C2. Various measurement results regarding these
embodiments as well as those of Embodiment C2 were summarized in
Table C6.
[0160] Embodiments C2, C21, and C22, where the BET specific surface
areas are not greater than 10.0 m.sup.2/g, have larger discharge
capacities and higher capacity retention ratios compared to
Embodiment C23, where the BET specific surface area is 20.0
m.sup.2/g.
Embodiment C24
[0161] In Embodiment C24, a negative active material was prepared
as follows: composite particle was prepared by treating 60 parts by
weight of the particle, where Si and SiO.sub.2 are contained in a
weight ratio of 1:1, and 40 parts by weight of artificial graphite
under nitrogen atmosphere by ball milling at 25.degree. C. for 30
minutes. Except for using the negative active material thus
prepared, the non-aqueous electrolyte secondary battery has an
identical configuration to that of Embodiment C1.
Embodiment C25
[0162] In Embodiment C25, a negative active material was prepared
as follows: composite particle was prepared by treating 40 parts by
weight of the particle, where Si and SiO.sub.2 are contained in a
weight ratio of 1:1, and 40 parts by weight of artificial graphite
under nitrogen atmosphere by ball milling at 25.degree. C. for 30
minutes; and after that, by means of the method (CVD) of thermally
decomposing methane at 900.degree. C., the surface of such
composite particle was coated with carbon material. Except for
using the negative active material thus prepared, the non-aqueous
electrolyte secondary battery has an identical configuration to
that of Embodiment C24.
Embodiment C26
[0163] In Embodiment C26, SiO was used in stead of SiO.sub.2.
Except for the above, the non-aqueous electrolyte secondary battery
has an identical configuration to that of Embodiment C25.
[0164] For the negative active materials in Embodiments C24 to C26,
measurement data of Raman spectroscopic analysis, thermogravimetry,
XRD, and BET specific surface area were taken according to the same
manner as described in Embodiment C1. In addition, for the
non-aqueous electrolyte secondary batteries in Embodiments C24 to
C26, charge/discharge performance was determined according to the
same manner as described in Embodiment C1. The results are shown in
Table C7, in which data from Comparative Examples C1 to C4 shown in
Table C1 was also included for comparison.
[0165] <Results>
[0166] In Embodiments C24 to C26, the capacity retention ratios are
higher than that of Comparative Example C1, where SiO.sub.x is not
contained; and the discharge capacities are larger than that of
Comparative Example C2, where Si is not contained. In addition, the
capacity retention ratios are higher than that of Comparative
Example C3, where carbon material is not contained in the composite
particle; and the discharge capacities are larger than that of
Comparative Example C4, where Si and SiO.sub.x are not
contained.
[0167] Embodiments C25 and C26, where the composite particle is
coated with the carbon material, are superior in the capacity
retention ratios compared to Embodiment C24.
Embodiments C27 to C31
[0168] In Embodiments C27 to C31, as the proportions of Si in the
particle containing Si and SiO.sub.2, those listed in Table C8 were
used. Except for the above, the non-aqueous electrolyte secondary
batteries have an identical configuration to that of Embodiment
C25.
[0169] Various measurement results regarding these embodiments as
well as those of Embodiment C25 and Comparative Examples C1 and C2
were summarized in Table C8.
[0170] Embodiments C25, C28, and C31, where the proportions of Si
in the particle containing Si and SiO.sub.2 fall within the range
of 20 wt. % to 80 wt. %, have larger discharge capacities compared
to Embodiment C27, where the proportion of Si stands at 10 wt.
%.
Embodiments C32 to C37
[0171] In Embodiments C32 to C37, as the proportions of the
additive amount of the artificial graphite which is mixed together
with the particle containing Si and SiO.sub.2, those listed in
Table C9 were used. Except for the above, the non-aqueous
electrolyte secondary batteries have an identical configuration to
that of Embodiment C25.
[0172] Various measurement results regarding these embodiments were
summarized in Table C9.
[0173] Embodiments C33 to C36, where the proportions of the
artificial graphite to the entire negative active material fall
within the range of 3 wt. % to 60 wt. %, have higher capacity
retention ratios compared to Embodiment C32, where the proportion
of the artificial graphite stands at 1 wt. %. On the other hand,
Embodiments C33 to C36 have larger discharge capacities compared to
Embodiment C37, where the proportion of the artificial graphite
stands at 70 wt. %.
[0174] In addition, Embodiments C34 to C36, where the proportions
of the total carbon material to the entire negative active material
fall within the range of 30 wt. % to 80 wt. %, have higher capacity
retention ratios compared to Embodiments C32 and C33, where the
proportions of the total carbon material stand at 21 wt. % and 23
wt. %, respectively. Embodiments C34 to C36 have larger discharge
capacities and higher capacity retention ratios compared to
Embodiment C37, where the proportion of the total carbon material
stands at 90 wt. %.
TABLE-US-00008 TABLE C1 Specific Capacity Particle (A) Coating
surface Discharge retention Si SiO.sub.2 SiO Carbon Carbon d(002)
area capacity ratio (wt. %) (wt. %) (wt. %) (wt. %) (wt. %) (nm)
(m.sup.2/g) (mAh) (%) EM C1 30 30 0 40 0 0.34 5 815 71 EM C2 20 20
0 40 20 0.34 5 774 82 EM C3 20 0 20 40 20 0.34 5 780 76 CE C1 40 0
0 40 20 0.34 5 812 49 CE C2 0 40 0 40 20 0.34 5 520 59 CE C3 40 40
0 0 20 0.345 5 820 43 CE C4 0 0 0 80 20 0.34 5 601 72
[0175] In Tables 1 to 9, EM in the first column refers to
Embodiment CE refers to Comparative Example; for example, EM C1
refers to Embodiment C1 and CE C1 refers to Comparative Example
C1.
TABLE-US-00009 TABLE C2 Proportion to Proportion to the entire the
sum of Si negative active material Specific Capacity and SiO.sub.2
Particle (A) Coating surface Discharge retention Si SiO.sub.2 Si
SiO.sub.2 Carbon Carbon d(002) area capacity ratio (wt. %) (wt. %)
(wt. %) (wt. %) (wt. %) (wt. %) (nm) (m.sup.2/g) (mAh) (%) CE C2 0
100 0 40 40 20 0.34 5 520 59 EM C4 10 90 4 36 40 20 0.34 5 672 61
EM C5 20 80 8 32 40 20 0.34 5 740 73 EM C6 40 60 16 24 40 20 0.34 5
768 76 EM C2 50 50 20 20 40 20 0.34 5 774 82 EM C7 60 40 24 16 40
20 0.34 5 782 77 EM C8 80 20 32 8 40 20 0.34 5 798 72 CE C1 100 0
40 0 40 20 0.34 5 812 49
TABLE-US-00010 TABLE C3 Specific Capacity Particle (A) Coating
surface Discharge retention Si SiO.sub.2 Carbon Carbon d(002) area
capacity ratio (wt. %) (wt. %) (wt. %) (wt. %) (nm) (m.sup.2/g)
(mAh) (%) EM C9 39.5 39.5 1 20 0.34 5 807 52 EM C10 38.5 38.5 3 20
0.34 5 802 69 EM C11 30 30 20 20 0.34 5 805 79 EM C12 20 20 40 20
0.34 5 774 82 EM C13 10 10 60 20 0.34 5 772 78 EM C14 5 5 70 20
0.34 5 682 68
TABLE-US-00011 TABLE C4 Specific Capacity Particle (A) Coating
surface Discharge retention Si SiO.sub.2 Carbon Carbon d(002) area
capacity ratio (wt. %) (wt. %) (wt. %) (wt. %) (nm) (m.sup.2/g)
(mAh) (%) EM C15 20 20 40 20 0.3354 5 780 73 EM C2 20 20 40 20 0.34
5 774 82 EM C16 20 20 40 20 0.37 5 709 65 EM C17 20 20 40 20 0.35 5
789 81
TABLE-US-00012 TABLE C5 Specific Capacity Particle (A) Coating
surface Discharge retention Si SiO.sub.2 Carbon Carbon d(002) area
capacity ratio (wt. %) (wt. %) (wt. %) (wt. %) (nm) (m.sup.2/g)
(mAh) (%) EM C18 29.75 29.75 40 0.5 0.34 5 811 80 EM C2 20 20 40 20
0.34 5 774 82 EM C19 10 10 40 40 0.34 5 752 83 EM C20 5 5 40 50
0.34 5 702 70
TABLE-US-00013 TABLE C6 Specific Capacity Particle (A) Coating
surface Discharge retention Si SiO.sub.2 Carbon Carbon d(002) area
capacity ratio (wt. %) (wt. %) (wt. %) (wt. %) (nm) (m.sup.2/g)
(mAh) (%) EM C21 20 20 40 20 0.34 1 782 79 EM C2 20 20 40 20 0.34 5
774 82 EM C22 20 20 40 20 0.34 10 776 70 EM C23 20 20 40 20 0.34 20
721 61
TABLE-US-00014 TABLE C7 Specific Capacity Particle (A) Coating
surface Discharge retention Si SiO.sub.2 SiO Carbon Carbon d(002)
area capacity ratio (wt. %) (wt. %) (wt. %) (wt. %) (wt. %) (nm)
(m.sup.2/g) (mAh) (%) EM C24 30 30 0 40 0 0.34 5 819 79 EM C25 20
20 0 40 20 0.34 5 782 84 EM C26 20 0 20 40 20 0.34 5 795 83 CE C1
40 0 0 40 20 0.34 5 812 49 CE C2 0 40 0 40 20 0.34 5 520 59 CE C3
40 40 0 0 20 0.345 5 820 43 CE C4 0 0 0 80 20 0.34 5 601 72
TABLE-US-00015 TABLE C8 Proportion to Proportion to the entire the
sum of Si negative active material Specific Capacity and SiO.sub.2
Particle (A) Coating surface Discharge retention Si SiO.sub.2 Si
SiO.sub.2 Carbon Carbon d(002) area capacity ratio (wt. %) (wt. %)
(wt. %) (wt. %) (wt. %) (wt. %) (nm) (m.sup.2/g) (mAh) (%) CE C2 0
100 0 40 40 20 0.34 5 520 69 EM C27 10 90 4 36 40 20 0.34 5 675 75
EM C28 20 80 8 32 40 20 0.34 5 749 79 EM C29 40 60 16 24 40 20 0.34
5 773 83 EM C25 50 50 20 20 40 20 0.34 5 782 84 EM C30 60 40 24 16
40 20 0.34 5 795 81 EM C31 80 20 32 8 40 20 0.34 5 803 77 CE C1 100
0 40 0 40 20 0.34 5 812 49
TABLE-US-00016 TABLE C9 Specific Capacity Particle (A) Coating
surface Discharge retention Si SiO.sub.2 Carbon Carbon d(002) area
capacity ratio (wt. %) (wt. %) (wt. %) (wt. %) (nm) (m.sup.2/g)
(mAh) (%) EM C32 39.5 39.5 1 20 0.34 5 815 67 EM C33 38.5 38.5 3 20
0.34 5 807 76 EM C34 30 30 20 20 0.34 5 802 79 EM C35 20 20 40 20
0.34 5 782 84 EM C36 10 10 60 20 0.34 5 776 81 EM C37 5 5 70 20
0.34 5 701 78
Embodiment D
Embodiment D1
[0176] To the particle consisting of both microcrystalline Si phase
and amorphous SiO.sub.x phase (hereinafter such particle is
referred to as the particle (S)), X-ray diffraction technique with
the use of CuK.alpha. radiation was utilized. As a result, on the
particle (S), diffraction peaks appeared in a range of diffraction
angle (2.theta.) from 46.degree. to 49.degree. and the half width
of the main diffraction peak appearing in said range was smaller
than 3.degree.(2.theta.).
[0177] The surface of such particle (S) was coated with carbon
using the method (CVD) of thermally decomposing benzene gas under
argon atmosphere at 1000.degree. C., so that the composite particle
(C) was prepared. The amount of the carbon coating was determined
to be 20 wt. % to the total amount of the particle (S) and the
carbon as coating material. The number average particle size of the
composite particle (C) was 10 .mu.m. The number average particle
size of particle is defined as a number average which can be
obtained by laser diffraction technique.
[0178] With the use of such composite particle (C), a non-aqueous
electrolyte secondary battery was produced according to the
following manner. First, 10 wt. % of the composite particle (C)
and, as the carbon material (D), 40 wt. % of meso carbon micro
beads (MCMB), 30 wt. % of natural graphite and 20.0 wt. % of
artificial graphite were mixed together to prepare a negative
active material. An illustration of this type of negative active
material can be seen in FIG. 8, which shows a mixture of carbon
material (D) 31 and composite particles (C) 60.
[0179] 97 wt. % of the above-obtained negative active material, 2
wt. % of styrene-butadiene rubber (SBR), and 1 wt. % of
carboxymethyl-cellulose (CMC) were mixed in water to prepare a
paste. The obtained paste was applied to a copper foil having a
thickness of 151 .mu.m so that the weight of the coating could be
1.15 mg/cm.sup.2 and the quantity of the negative active material
to be housed in the battery could be 2 g, and then dried at
150.degree. C. to evaporate water. This process was performed on
both sides of the copper foil, which then compressed and molded by
roll pressing. Thus, a negative electrode plate, or the copper foil
both sides of which were coated with the negative composite layer,
was prepared.
[0180] Next, 90 wt. % of lithium cobalt oxide, 5 wt. % of acetylene
black, and 5 wt. % of poly(vinylidene fluoride) (PVdF) were
dispersed in NMP to make a paste. The obtained paste was applied to
an aluminum foil having a thickness of 20 .mu.m so that the density
could be 2.5 mg/cm.sup.2 and the quantity of the positive active
material to be housed in the battery could be 5.3 g, and then dried
at 150.degree. C. to evaporate NMP. The above-described process was
performed on both sides of the aluminum foil, which then compressed
and molded by roll pressing. Thus, a positive electrode plate, or
the aluminum foil both sides of which were coated with the positive
composite layer, was prepared.
[0181] The positive and negative electrode plates thus prepared
were overlapped and wound with a polyethylene separator, with
continuous porosity having a thickness of 20 .mu.m and a porosity
of 40%, being placed between them, and this element was housed in
the case having 48 mm in height, 30 mm in width and 4.2 mm in
thickness to form a non-aqueous electrolyte secondary battery of a
prismatic type. Finally, the case was filled with a non-aqueous
electrolyte solution; thus the non-aqueous electrolyte secondary
battery of a prismatic type of Embodiment 1 was prepared. The used
non-aqueous electrolyte solution was prepared as follows: ethylene
carbonate (EC) and ethylmethyl carbonate (EMC) were mixed together
in a volume ratio of 1:1, and 1 mol/l of LiPF.sub.6 was dissolved
in the mixed solvent thus prepared. The rated capacity of the
battery was 700 mAh.
Embodiment D2
[0182] The particle (S) and artificial graphite of a scale-like
shape were granulated in a weight mixture ratio of 1:1 by means of
ball milling. The surface of the particle thus granulated was
coated with carbon using the method (CVD) of thermally decomposing
benzene gas under argon atmosphere at 10000.degree. C., so that the
composite particle (C) was prepared. The amount of the carbon
coating was determined to be 20 wt. % to the weight of the
composite particle (C). The number average particle size of the
composite particle (C) coated with the carbon was 10 .mu.m.
[0183] 10 wt. % of the composite particle (C) and, as the carbon
material (D), 40 wt. % of MCMB, 30 wt. % of natural graphite and
20.0 wt. % of artificial graphite were mixed together to prepare a
negative active material. Except for the above, the non-aqueous
electrolyte secondary battery of a prismatic type has an identical
configuration to that of Embodiment D1. This battery was termed
Embodiment D2.
Comparative Example D1
[0184] As a negative active material, 100 wt. % of natural graphite
was used. Except for the above, the non-aqueous electrolyte
secondary battery of a prismatic type has an identical
configuration to that of Embodiment D1. This battery was termed
Comparative Example D1.
Comparative Example D2
[0185] 10 wt. % of the particle (S) having a number average
particle size of 10 .mu.m, and, as the carbon material (D), 40 wt.
% of MCMB, 30 wt. % of natural graphite and 20.0 wt. % of
artificial graphite were used. Except for the above, the
non-aqueous electrolyte secondary battery of a prismatic type has
an identical configuration to that of Embodiment D1. This battery
was termed Comparative Example D2.
Comparative Example D3
[0186] As a negative active material, the composite particle (C)
prepared in Embodiment D1 was used alone. The amount of the carbon
coating was determined to be 20 wt. % to the weight of the
composite particle (C). The number average particle size of the
composite particle (C) was 10 .mu.m. Except for the above, the
non-aqueous electrolyte secondary battery of a prismatic type has
an identical configuration to that of Embodiment D1. This battery
was termed Comparative Example D3.
Comparative Example D4
[0187] The surface of silicon particle was coated with carbon using
the method (CVD) of thermally decomposing benzene gas under argon
atmosphere at 1000.degree. C. The amount of the carbon coating was
determined to be 20 wt. % to the total amount of the silicon
particle and the carbon as coating material. The number average
particle size of the silicon particle coated with the carbon was 1
.mu.m. Except for using such carbon-coated Si particle as a
negative active material, the non-aqueous electrolyte secondary
battery of a prismatic type has an identical configuration to that
of Embodiment D1. This battery was termed Comparative Example
D4.
[0188] The structures of the negative active materials used in
Embodiments D1 and D2 and Comparative Examples D1 to D4 were
summarized in Table D1.
TABLE-US-00017 TABLE D1 Particle to be coated & coating
material, and composition of composite particle (C) Composition of
Particle to be coated Composition of (C) Number negative active
& coating material (wt. %) average material Particle Particle
particle (wt. %) to be Coating to be Coating size of (C) Composite
Carbon coated material coated material (.mu.m) particle (C)
material (D) EM D1 Particle(S) Carbon 80 20 10 10 90 EM D2
Particle(S) + Carbon 40 + 40 20 10 10 90 Carbon CM D1 -- -- -- --
-- 0 100 CM D2 Particle(S) -- 100 -- 10 10 90 CM D3 Particle(S)
Carbon 80 20 10 100 0 CM D4 Silicon Carbon 80 20 1 100 0
particle
[0189] In Tables D1 to D14, EM in the first column refers to
Embodiment and CE refers to Comparative Example; for example, EM D1
refers to Embodiment D1 and CE D1 refers to Comparative Example
D1.
Embodiments D3 to D7, D56, and D57
[0190] Using the CVD method as described in Embodiment D1, the
surface of the particle (S) was coated with carbon, and the
composite particle (C) was prepared. The amount of the carbon
coating was determined to be 20 wt. % to the weight of the
composite particle (C). The number average particle size of the
carbon-coated SiO particle was 1 .mu.m.
[0191] By mixing such composite particle (C) with the carbon
material (D), a negative active material was prepared. As the
carbon material (D), a mixture of MCMB, natural graphite, and
artificial graphite were used. Except for the composition of the
negative active material, the non-aqueous electrolyte secondary
batteries of a prismatic type have an identical configuration to
that of Embodiment D1.
[0192] In Embodiments D3 to D7, the following compositions were
used to prepare the negative active materials, respectively: 1 wt.
% of the composite particle (C), and 40 wt. % of MCMB, 39 wt. % of
natural graphite and 20 wt. % of artificial graphite in Embodiment
D3; 5 wt. % of the composite particle (C), and 40 wt. % of MCMB, 35
wt. % of natural graphite and 20 wt. % of artificial graphite in
Embodiment D4; 10 wt. % of the composite particle (C), and 40 wt. %
of MCMB, 30 wt. % of natural graphite and 20 wt. % of artificial
graphite in Embodiment D5; 20 wt. % of the composite particle (C),
and 40 wt. % of MCMB, 20 wt. % of natural graphite and 20 wt. % of
artificial graphite in Embodiment D6; and 30 wt. % of the composite
particle (C), and 40 wt. % of MCMB, 10 wt. % of natural graphite
and 20 wt. % of artificial graphite in Embodiment D7.
[0193] In Embodiments D56 and D57, the following compositions were
used to prepare the negative active materials, respectively: 0.5
wt. % of the composite particle (C), and 40 wt. % of MCMB, 39.5 wt.
% of natural graphite and 20 wt. % of artificial graphite in
Embodiment D56; and 35 wt. % of the composite particle (C), and 40
wt. % of MCMB, 5 wt. % of natural graphite and 20 wt. % of
artificial graphite in Embodiment D57.
[0194] The structures of the negative active materials used in
Embodiments D3 to D7, D56, and D57 were summarized in Table D2.
TABLE-US-00018 TABLE D2 Composition Composition of composite Number
average of negative particle (C) particle size active material (wt.
%) of composite (wt. %) Parti- Car- particle(C) Composite Carbon
cle (S) bon (.mu.m) particle(C) material(D) EM D56 80 20 1 0.5 99.5
EM D3 80 20 1 1 99 EM D4 80 20 1 5 95 EM D5 80 20 1 10 90 EM D6 80
20 1 20 80 EM D7 80 20 1 30 70 EM D57 80 20 1 35 65
Embodiments D8 to D12
[0195] Using the CVD method as described in Embodiment D1; the
surface of the particle (S) was coated with carbon, and the
composite particle (C) was prepared. Having a negative active
material which was prepared by mixing such composite particle (C)
with the carbon material (D), a non-aqueous electrolyte secondary
battery was produced. The following composition was used to prepare
the negative active material: 10 wt. % of the composite particle
(C), and 40 wt. % of MCMB, 80 wt. % of natural graphite and 20 wt.
% of artificial graphite.
[0196] Except for the composition of the composite particle (C), or
the proportion of the weight of the carbon to the weight of the
composite particle (C), the non-aqueous electrolyte secondary
batteries of a prismatic type have an identical configuration to
that of Embodiment D1.
[0197] In Embodiments D8 to D12, the respective carbon compositions
in the composite particle (C) and the respective number average
particle sizes of the composite particle (C) were as follows: 0.5
wt. % and 1.0 .mu.m in Embodiment D8; 1 wt. % and 1.0 .mu.m in
Embodiment D9; 10 wt. % and 1.0 .mu.m in Embodiment D10; 30 wt. %
and 1.1 .mu.m in Embodiment D11; and 40 wt. % and 1.2 .mu.m in
Embodiment D12.
[0198] The structures of the negative active materials used in
Embodiments D8 to D12 were summarized in Table D3.
TABLE-US-00019 TABLE D3 Composition Composition of composite Number
average of negative particle (C) particle size active material (wt.
%) of composite (wt. %) Parti- Car- particle(C) Composite Carbon
cle (S) bon (.mu.m) particle(C) mate rial(D) EM D8 99.5 0.5 About
1.0 10 90 EM D9 99 1 About 1.0 10 90 EM D10 90 10 About 1.0 10 90
EM D11 70 30 About 1.0 10 90 EM D12 60 40 About 1.0 10 90
Embodiments D18 to D16
[0199] Using the CVD method as described in Embodiment D1, the
surface of the particle (S) was coated with carbon, and the
composite particle (C) was prepared. The amount of the carbon
coating was determined to be 20 wt. % to the weight of the
composite particle (C). Having a negative active material which was
prepared by mixing such composite particle (C) with the carbon
material (D), a non-aqueous electrolyte secondary battery was
produced. The following composition was used to prepare the
negative active material: 10 wt. % of the composite particle (C),
and 40 wt. % of MCMB, 30 wt. % of natural graphite and 20 wt. % of
artificial graphite
[0200] Except for using the composite particle (C) having a
different number average particle size, the non-aqueous electrolyte
secondary batteries of a prismatic type have an identical
configuration to that of Embodiment D1.
[0201] In Embodiments D13 to D16, the respective number average
particle sizes of the composite particle (C) were as follows: 0.05
.mu.m in Embodiment D13, 0.1 .mu.m in Embodiment D14, 20 .mu.m in
Embodiment D15, and 30 .mu.m in Embodiment DIG.
[0202] The structures of the negative active materials used in
Embodiments D13 to D16 were summarized in Table D4, in which the
structure used in Embodiment D1 was also included.
TABLE-US-00020 TABLE D4 Composition Composition of composite Number
average of negative particle (C) particle size active material (wt.
%) of composite (wt. %) Parti- Car- particle(C) Composite Carbon
cle (S) bon (.mu.m) particle(C) material(D) EM D13 80 20 0.05 10 90
EM D14 80 20 0.1 10 90 EM D1 80 20 10 10 90 EM D15 80 20 20 10 90
EM D16 80 20 30 10 90
Embodiments D17 to D21, D58, and D59
[0203] The particle (S) and graphite of a scale-like shape were
granulated in a weight mixture ratio of 50:50 using a ball milling
machine. After that, using the method (CVD) as described in
Embodiment D1, the surface of the particle thus granulated was
coated with carbon, and the composite-particle (C) was prepared.
The amount of the carbon coating was determined to be 20 wt. % to
the weight of the composite particle (C). The number average
particle size of the composite particle (C) was 20 .mu.m.
[0204] Having a negative active material which was prepared by
mixing such composite particle (C) with the carbon material (D), a
non-aqueous electrolyte, secondary battery was produced. As the
carbon material (D), a mixture of MCMB, natural graphite, and
artificial graphite were used. Except for the composition of the
negative active material, the non-aqueous electrolyte secondary
batteries of a prismatic type have an identical configuration to
that of Embodiment D1.
[0205] In Embodiments D17 to D21, the following compositions were
used to prepare the negative active materials, respectively: 1 wt.
% of the composite particle (C), and 40 wt. % of MCMB, 39 wt. % of
natural graphite and 20 wt. % of artificial graphite in Embodiment
D17; 5 wt. % of the composite particle (C), and 40 wt. % of MCMB,
35 wt. % of natural graphite and 20 wt. % of artificial graphite in
Embodiment D18; 10 wt. % of the composite particle (C), and 40 wt.
% of MCMB, 30 wt. % of natural graphite and 20 wt. % of artificial
graphite in Embodiment D19; 20 wt. % of the composite particle (C),
and 40 wt. % of MCMB, 20 wt. % of natural graphite and 20 wt. % of
artificial graphite in Embodiment D20; and 30 wt. % of the
composite particle (C), and 40 wt. % of MCMB, 10 wt. % of natural
graphite and 20 wt. % of artificial graphite in Embodiment D21.
[0206] In Embodiments D58 and D59, the following compositions were
used to prepare the negative active materials, respectively: 0.5
wt. % of the composite particle (C), and 40 wt. % of MCMB, 39.5 wt.
% of natural graphite and 20 wt. % of artificial graphite in
Embodiment D58; and 35 wt. % of the composite particle (C), and 40
wt. % of MCMB, 5 wt. % of natural graphite and 20 wt. % of
artificial graphite in Embodiment 59.
[0207] The structures of the negative active materials used in
Embodiments D17 to D21, D58 and D59 were summarized in Table
D5.
TABLE-US-00021 TABLE D5 Composition of Number Composition of
negative Composition of composite particle(C) average active
material granulated particle (wt. %) particle (wt. %) (wt. %)
Granulated Carbon size of (C) Composite Carbon Particle (S)
Graphite particle coating (.mu.m) particle (C) material (D) EM D58
50 50 80 20 20 0.5 99.5 EM D17 50 50 80 20 20 1 99 EM D18 50 50 80
20 20 5 95 EM D19 50 50 80 20 20 10 90 EM D20 50 50 80 20 20 20 80
EM D21 50 50 80 20 20 30 70 EM D59 50 50 80 20 20 35 65
Embodiments D22 to D27
[0208] The particle (S) and graphite of a scale-like shape were
granulated in a weight mixture ratio of 50:50 using a ball milling
machine. After that, using the method (CVD) as described in
Embodiment D1, the surface of the particle thus granulated was
coated with carbon, and the composite particle (C) was
prepared.
[0209] Having a negative active material which was prepared by
mixing such composite particle (C) with the carbon material (D), a
non-aqueous electrolyte secondary battery was produced. The
following composition was used to prepare the negative active
material: 10 wt. % of the composite particle (C), and 40 wt. % of
MCMB, 40 wt. % of natural graphite and 20 wt. % of artificial
graphite. Except for the composition of the composite particle (C),
or the proportion of the weight of the carbon to the weight of the
composite particle (C), the non-aqueous electrolyte secondary
batteries of a prismatic type have an identical configuration to
that of Embodiment D1.
[0210] In Embodiments D22 to D27, the respective carbon
compositions used in the composite particle (C) and the respective
number average particle sizes of the composite particle (C) were as
follows: 0.5 wt. % and approximately 20 .mu.m in Embodiment D22; 1
wt. % and approximately 20 .mu.m in Embodiment D23; 10 wt. % and
approximately 20.4 .mu.m in Embodiment D24; 20 wt. % and
approximately 20.8 .mu.m in Embodiment D25; 30 wt. % and
approximately 21.2 .mu.m in Embodiment D26; and 40 wt. % and
approximately 21.8 .mu.m in Embodiment D27.
[0211] The structures of the negative active materials used in
Embodiments D22 to D27 were summarized in Table D6.
TABLE-US-00022 TABLE D6 Composition of Number Mixture ratio of
negative Composition of composite particle(C) average active
material granulated particle (wt. %) particle (wt. %) (wt. %)
Granulated Carbon size of (C) Composite Carbon Particle (S)
Graphite particle coating (.mu.m) particle (C) material (D) EM D22
50 50 99.5 0.5 20 10 90 EM D23 50 50 99 1 20 10 90 EM D24 50 50 90
10 20.4 10 90 EM D25 50 50 80 20 20.8 10 90 EM D26 50 50 70 30 21.2
10 90 EM D27 50 50 60 40 21.5 10 90
Embodiments D28 to D32
[0212] The particle (S) and graphite of a scale-like shape were
granulated using a ball milling machine. After that, using the
method (CVD) as described in Embodiment D1, the surface of the
particle thus granulated was coated with carbon, and the composite
particle (C) was prepared. The amount of the carbon coating was
determined to be 20 wt. % to the weight of the composite particle
(C). The number average particle size of the composite particle (C)
was approximately 20 .mu.m.
[0213] Having a negative active material which was prepared by
mixing such composite particle (C) with the carbon material (D), a
non-aqueous electrolyte secondary battery was produced. The
following composition was used to prepare the negative active
material: 10 wt. % of the composite particle (C), and 40 wt. % of
MCMB, 40 wt. % of natural graphite and 20 wt. % of artificial
graphite. Except for the mixture ratio of the particle (S) to the
graphite of a scale-like shape in the granulated particle, the
non-aqueous electrolyte secondary batteries of a prismatic type
have an identical configuration to that of Embodiment D1.
[0214] In Embodiments D28 to D32, the respective weight mixture
ratios of the particle (S) to the graphite of a scale-like shape in
the granulated particle were as follows: 10:90 in Embodiment D28;
20:80 in Embodiment D29; 40:60 in Embodiment D30; 70:30 in
Embodiment D31; and 80:20 in Embodiment D32.
[0215] The structures of the negative active materials used in
Embodiments D28 to D32 were summarized in Table D7, in which the
structure used in Embodiment D19 was also included.
TABLE-US-00023 TABLE D7 Composition of Number Composition of
negative Composition of composite particle(C) average active
material granulated particle (wt. %) particle (wt. %) (wt. %)
Granulated Carbon size of (C) Composite Carbon Particle (S)
Graphite particle coating (.mu.m) particle (C) material (D) EM D28
10 90 80 20 20 10 90 EM D29 20 80 80 20 20 10 90 EM D19 50 50 80 20
20 10 90 EM D30 40 60 80 20 20 10 90 EM D31 70 30 80 20 20 10 90 EM
D32 80 20 80 20 20 10 90
Embodiments D33 to D37
[0216] The particle (S) and graphite of a scale-like shape were
granulated in a weight mixture ratio of 50:50 using a ball milling
machine. After that, using the method (CVD) as described in
Embodiment D1, the surface of the granulated composite particle was
coated with carbon, and the composite particle (C) was prepared.
The amount of the carbon coating was determined to be 20 wt. % to
the weight of the composite particle (C).
[0217] Having a negative active material which was prepared by
mixing such composite particle (C) with the carbon material (D), a
non-aqueous electrolyte secondary battery was produced. The
following composition was used to prepare the negative active
material: 10 wt. % of the composite particle (C), and 40 wt. % of
MCMB, 40 wt. % of natural graphite and 20 wt. % of artificial
graphite. Except for using composite particle (C) which is
different in "the respective number average particle sizes", the
non-aqueous electrolyte secondary batteries of a prismatic type
have an identical configuration to that of Embodiment D1.
[0218] In Embodiments D33 to D37, the respective number average
particle sizes of the composite particle (C) were as follows: 0.05
.mu.m in Embodiment D33, 0.1 .mu.m in Embodiment D34, 20 .mu.m in
Embodiment D35, 30 .mu.m in Embodiment D36, and 40 .mu.m in
Embodiment D37.
[0219] The structures of the negative active materials used in
Embodiments D33 to D37 were summarized in Table D8, in which the
structure used in Embodiment D2 was also included.
TABLE-US-00024 TABLE D8 Composition of Number Composition of
negative Composition of composite particle(C) average active
material granulated particle (wt. %) particle (wt. %) (wt. %)
Granulated Carbon size of (C) Composite Carbon Particle (S)
Graphite particle coating (.mu.m) particle (C) material (D) EM D33
50 50 80 20 0.05 10 90 EM D34 50 50 80 20 0.1 10 90 EM D2 50 50 80
20 10 10 90 EM D35 50 50 80 20 20 10 90 EM D36 50 50 80 20 30 10 90
EM D37 50 50 80 20 40 10 90
Embodiment D38
[0220] Carbon and the particle (S) were mixed and, using the
mechanical milling method, the surface of the particle (S) was
coated with the carbon; thus the composite particle (C) was
prepared. The amount of the carbon coating was determined to be 20
wt. % to the weight of the composite particle (C). The number
average particle size of the composite particle (C) was 10
.mu.m.
[0221] Using such composite particle (C), a non-aqueous electrolyte
secondary battery was produced. The following composition was used
to prepare the negative active material: 10 wt. % of the composite
particle (C), and 40 wt. % of MCMB, 30 wt. % of natural graphite
and 20 wt. % of artificial graphite. Except for the negative active
material, the non-aqueous electrolyte secondary battery of a
prismatic type has an identical configuration to that of Embodiment
D1. This battery was termed Embodiment D38.
Embodiment D39
[0222] According to the same manner as described in Embodiment D38,
the surface of the particle (S) was coated with carbon using the
mechanical milling method, and the composite particle (C) was
prepared. 10 wt. % of the composite particle (C), and, as the
carbon material (D), 40 wt. % of meso carbon fiber containing
boron, 30 wt. % of natural graphite and 20 wt. % of artificial
graphite were mixed together to prepare a negative active material.
Except for the negative active material, the non-aqueous
electrolyte secondary battery of a prismatic type has an identical
configuration to that of Embodiment D1. This battery was termed
Embodiment D39.
Embodiment D40
[0223] According to the same manner as described in Embodiment D38,
the surface of the particle (S) was coated with carbon using the
mechanical milling method, and the composite particle (C) was
prepared. 10 wt. % of the composite particle (C), and, as the
carbon material. (D), 70 wt. % of natural graphite and 20 wt. % of
artificial graphite were mixed together to prepare a negative
active material. Except for the negative active material, the
non-aqueous electrolyte secondary battery of a prismatic type has
an identical configuration to that of Embodiment D1. This battery
was termed Embodiment D40.
Embodiment D41
[0224] Silicon particle and graphite of a scale-like shape were
granulated in a weight mixture ratio of 50:50 using a ball milling
machine. After that, using the method (CVD) as described in
Embodiment D1, the surface of the particle thus granulated was
coated with carbon, and the composite particle (C) was prepared.
The amount of the carbon coating was determined to be 20 wt. % to
the weight of the composite particle (C). The number average
particle size of the composite particle (C) was 20 .mu.m.
[0225] 10 wt. % of the composite particle (C), and, as the carbon
material (D), 40 wt. % of MCMB, 30 wt. % of natural graphite and 20
wt. % of artificial graphite were mixed together to prepare a
negative active material. Except for the composition of the
negative active material, the non-aqueous electrolyte secondary
battery of a prismatic type has an identical configuration to that
of Embodiment D1. This battery was termed Embodiment D41.
Embodiment D42
[0226] ZrSi.sub.2 particle and graphite of a scale-like shape were
granulated in a weight mixture ratio of 50:50 using a ball milling
machine. Except for the above, the non-aqueous electrolyte
secondary battery of a prismatic type has an identical
configuration to that of Embodiment D1. This battery was termed
Embodiment D42.
Embodiment D43
[0227] The SiO particle consisting of amorphous single-phase
(identified by the peak of Si in X-ray diffraction pattern) and
graphite of a scale-like shape were granulated in a weight mixture
ratio of 50:50 using a ball milling machine. Except for the above,
the non-aqueous electrolyte secondary battery of a prismatic type
has an identical configuration to that of Embodiment D41. This
battery was termed Embodiment D43.
[0228] The structures of the negative active materials used in
Embodiments D38 to D43 were summarized in Tables D9 and D10. In the
"MCMB" column of Embodiment D39 in Table 10, the value of
boron-containing meso carbon fiber is entered.
TABLE-US-00025 TABLE D9 Particle to be coated Mixture ratio
Composition (wt. %) Silicon- Silicon- Carbon containing containing
coating particle Carbon particle Carbon method EM D38 SiO -- 100 --
Mechanical milling EM D39 SiO -- 100 -- Mechanical milling EM D40
SiO -- 100 -- Mechanical milling EM 41 Si Scale-like 50 50 CVD
graphite EM D42 ZrSi.sub.2 Scale-like 50 50 CVD graphite EM D43
amorphous Scale-like 50 50 CVD single- graphite phase SiO
TABLE-US-00026 TABLE D10 Composition of composite Composition of
particle (C) (wt. %) negative active material (wt. %) Coated Carbon
Number average Composite Natural Artificial particle coating
particle size of (C) (.mu.m) particle (C) MCMB graphite graphite EM
80 20 10 10 40 30 20 D38 EM 80 20 10 10 40 30 20 D39 EM 80 20 10 10
0 70 20 D40 EM 80 20 20 10 40 30 20 D41 EM 80 20 20 10 40 30 20 D42
EM 80 20 20 10 40 30 20 D43
Embodiments D44 to D49
[0229] The particle (S) and graphite of a scale-like shape were
granulated in a weight mixture ratio of 50:50 using a ball milling
machine. After that, the granulated particle was immersed in an
electrolytic bath, and by electroless plating, the surface of such
particle was coated with copper (Cu); thus, the composite particle
(C) was prepared.
[0230] Having a negative active material which was prepared by
mixing such composite particle (C) with the carbon material (D), a
non-aqueous electrolyte secondary battery was produced. The
following composition was used to prepare the negative active
material: 10 wt. % of the composite particle (C), and 40 wt. % of
MCMB, 40 wt. % of natural graphite and 20 wt. % of artificial
graphite. Except for the amount of Cu coating to the weight of the
composite particle (C), the non-aqueous electrolyte secondary
batteries of a prismatic type have an identical configuration to
that of Embodiment D1.
[0231] In Embodiments D44 to D49, the respective amounts of Cu
coating in the composite particle (C) and the respective number
average particle sizes of the composite particle (C) were as
follows: 0.5 wt. % and approximately 20 .mu.m in Embodiment D44; 1
wt. % and approximately 20 .mu.m in Embodiment D45; 10 wt. % and
approximately 20.51 .mu.m in Embodiment D46; 20 wt. % and
approximately 20.9 .mu.m in Embodiment D47; 30 wt. % and
approximately 21.5 .mu.m in Embodiment D48; and 40 wt. % and
approximately 21.7 .mu.m in Embodiment D49.
[0232] The structures of the negative active materials used in
Embodiments D44 to D49 were summarized in Table D11.
TABLE-US-00027 TABLE D11 Composition of Composition of Number
Composition of granulated composite average negative active
particle particle (C) particle material (wt. %) (wt. %) (wt. %)
size of Composite Carbon Particle Granulated Cu (C) particle
material (S) Graphite particle coating (.mu.m) (C) (D) EM D44 50 50
99.5 0.5 20 10 90 EM D45 50 50 99 1 20 10 90 EM D46 50 50 90 10
20.5 10 90 EM D47 50 50 80 20 20.9 10 90 EM D48 50 50 70 30 21.5 10
90 EM D49 50 50 60 40 21.7 10 90
Embodiments D50 to D55
[0233] The particle (S) and graphite of a scale-like shape were
granulated in a weight mixture ratio of 50:50 using a ball milling
machine. After that, the granulated particle was immersed in an
electrolytic bath, and by electroless plating, the surface of such
particle was coated with nickel (Ni); thus, the composite particle
(C) was prepared. Except for the above, the non-aqueous electrolyte
secondary batteries of a prismatic type have an identical
configuration to that of Embodiment D44.
[0234] In Embodiments D50 to D55, the respective amounts of Ni
coating in the composite particle (C) and the respective number
average particle sizes of the composite particle (C) were as
follows: 0.5 wt. % and approximately 20 .mu.m in Embodiment D50; 1
wt. % and approximately 20.1 .mu.m in Embodiment D51; 10 wt. % and
approximately 20.4 .mu.m in Embodiment D52; 20 wt. % and
approximately 20.8 .mu.m in Embodiment D53; 30 wt. % and
approximately 21.3 .mu.m in Embodiment D54; and 40 wt. % and
approximately 21.5 .mu.m in Embodiment D55.
[0235] The structures of the negative active materials used in
Embodiments D50 to D55 were summarized in Table D12.
TABLE-US-00028 TABLE D12 Composition of Composition of Number
Composition of granulated composite average negative active
particle particle (C) particle material (wt. %) (wt. %) (wt. %)
size of Composite Carbon Particle Granulated Ni (C) particle
material (S) Graphite particle coating (.mu.m) (C) (D) EM D50 50 50
99.5 0.5 20 10 90 EM D51 50 50 99 1 20.1 10 90 EM D52 50 50 90 10
20.4 10 90 EM D53 50 50 80 20 20.8 10 90 EM D54 50 50 70 30 21.3 10
90 EM D55 50 50 60 40 21.5 10 90
[0236] (Charge/Discharge Measurement)
[0237] Each battery prepared as above was charged at a constant
current of 700 mA at a temperature of 25.degree. C. until the
voltage reached 4.2 V, subsequently charged at a constant voltage
of 4.2 V for 2 hours, and then discharged at a constant current of
700 mA until the voltage dropped to 2.0 V. These steps were taken
as one cycle and the charge/discharge test was repeated 500 cycles.
Table D13 shows the discharge capacity at the 1.sup.st cycle
(initial discharge) and the capacity retention ratio for the
batteries of Embodiments D1 to D43, D56 to D59, and Comparative
Examples D1 to D4; and Table D14 shows those for the batteries of
Embodiments D44 to D55. Here, "capacity retention ratio" means the
ratio of the discharge capacity at the 500.sup.th cycle to the one
at the 1.sup.st cycle (expressed in percentage).
TABLE-US-00029 TABLE D13 Capacity retention Discharge capacity
ratio (mAh) (%) EM D1 749 75 EM D2 742 84 EM D3 730 80 EM D4 750 86
EM D5 752 85 EM D6 755 76 EM D7 754 68 EM D8 760 56 EM D9 752 72 EM
D10 754 86 EM D11 739 78 EM D12 700 76 EM D13 760 59 EM D14 751 71
EM D15 753 69 EM D16 755 54 EM D17 719 83 EM D18 732 82 EM D19 742
84 EM D20 747 79 EM D21 741 74 EM D22 745 61 EM D23 743 74 EM D24
740 78 EM D25 736 82 EM D26 728 80 EM D27 680 78 EM D28 701 80 EM
D29 739 82 EM D30 743 81 EM D31 747 77 EM D32 732 51 EM D33 741 52
EM D34 745 69 EM D35 744 73 EM D36 743 79 EM D37 740 57 EM D38 750
69 EM D39 743 83 EM D40 747 53 EM D41 741 74 EM D42 742 76 EM D43
751 65 CE D1 635 80 CE D2 630 10 CE D3 370 79 CE D4 820 9 EM D56
690 78 EM D57 754 18 EM D58 672 79 EM D59 739 22
TABLE-US-00030 TABLE D14 Capacity retention Initial capacity ratio
(mAh) (%) EM D44 735 49 EM D45 734 78 EM D46 729 79 EM D47 723 82
EM D48 715 81 EM D49 689 78 EM D50 732 52 EM D51 732 75 EM D52 715
77 EM D53 712 78 EM D54 709 82 EM D55 662 77
[0238] From the comparison of the results of Embodiments D1 to D43,
D56 to D59, and Comparative Examples D1 to D4, the following were
revealed. Embodiments D1, D2, and Comparative Examples D1 to D4
were compared. In Comparative Example D1, where conventional
graphite alone was used as the negative active material, the
initial capacity was 635 mAh and the capacity retention ratio was
80%; meanwhile, in Comparative Example D2, where a mixture of SiO
and carbon material was used as the negative active material, the
initial capacity was about the same level but the capacity
retention ratio was extremely low. In addition, in Comparative
Example D3, where the SiO particle alone, the surface of which was
coated with carbon, was used as the negative active material, the
capacity retention ratio was about the same level but the initial
capacity was much smaller, as compared to Comparative Example D1.
Moreover, in Comparative Example D4, where the Si particle alone,
the surface of which was coated with carbon, was used as the
negative active material, the initial capacity was larger but the
capacity retention ratio was extremely lower, as compared to
Comparative Example D1.
[0239] In addition, in the comparison of Embodiments D1 and D2 with
Comparative Examples D1 to D4, the initial capacities were larger
and the capacity retention ratios were superior in Embodiments D1
and D2. As described previously, in Embodiment D1, a mixture of
carbon-coated SiO and carbon material was used as the negative
active material; and in Embodiment D2, the surface of the mixed
particle of SiO particle and scale-like artificial graphite was
coated with carbon to prepare composite particle, and a mixture of
such composite particle and carbon material was used as the
negative active material. From these results, it is believed that
electronic conductivity improves by coating the surface of SiO
particle with carbon.
[0240] Next, Embodiments D3 to D7, D56, and D57 were compared;
where a mixture of carbon-coated SiO particle and carbon material
was used as the negative active material and a different mixture
ratio between the carbon-coated SiO particle and the carbon
material was applied to each embodiment. In Embodiments D3 to D7,
where the compositions of the carbon-coated SiO particle in the
total amount of the carbon-coated SiO particle and the carbon
material fall within the range of 1 to 30 wt. %, the initial
capacities were large and the capacity retention ratios were
significantly high, too. Meanwhile, in Embodiment D56, where the
composition of the carbon-coated SiO particle stood at 0.5 wt. %,
the content of the SiO particle highly capable of absorbing lithium
was too small to attain a sufficient initial capacity for the
battery; and in Embodiment D57, where the composition of the
carbon-coated SiO particle stood at 35 wt. %, the
expansion/contraction of the negative electrode plate was so large
that current collection performance was caused to be deteriorated
and the capacity retention ratio became significantly low.
Therefore, from the viewpoint of the cycle performance and
discharge capacity, when a mixture of the carbon-coated SiO
particle and the carbon material is used as the negative active
material, it is preferable that the composition of the
carbon-coated SiO particle in the total amount of the carbon-coated
SiO particle and the carbon material lie in the range of 1 to 30
wt. %.
[0241] Next, Embodiments D8 to D12 were compared; where the
composition of the carbon with which the surface of SiO particle
was coated in the total amount of the SiO particle and the carbon
on the surface of the SiO particle was varied. In Embodiments D9 to
D11, where the compositions of the carbon fall within the range of
1 to 30 wt. %, the initial capacities were large and the capacity
retention ratios were high, too. Meanwhile, in Embodiment 8, where
the composition of the carbon was 0.5 wt. %, the desired effect was
hardly obtained because the capacity retention ratio was rather
low, and in Embodiment D12, where the composition of the carbon was
40 wt. %, the content of the SiO particle highly capable of
absorbing lithium was small, so that the initial capacity became
rather low. Therefore, it is more preferable that the composition
of the carbon with which the surface of the SiO particle is coated
in the total amount of the SiO particle and the carbon on the
surface of the SiO particle lie in the range of 1 to 30 wt. %.
[0242] Next, Embodiments D1, and D13 to D16 were compared; where
the number average particle size of the SiO particle, the surface
of which was coated with carbon, was varied. In Embodiments D1, D14
and D15, where the number average particle sizes were in the range
of 0.1 to 20 .mu.m, large initial capacities and high capacity
retention ratios were attained. Meanwhile, in Embodiment D13, where
the number average particle size was 0.05 .mu.m, it was difficult
to prepare and handle the active material, so that the capacity
retention ratio became rather low. In Embodiment D16, in addition,
where the number average particle size was 30 .mu.m, the negative
electrode plate was hard to be prepared, so that the capacity
retention ratio became rather low. Therefore, it is more preferable
that the number average particle size of the SiO particle, the
surface of which is coated with carbon, lie in the range of 0.1 to
20 .mu.m.
[0243] Hereinafter, the results will be compared in terms of the
following case; the composite particle was prepared by mixing SiO
particle and graphite of a scale-like shape, the surface of the
composite particle was coated with carbon, and a mixture of the
carbon-coated composite particle and carbon material was used as
the negative active material.
[0244] First, Embodiments D17 to D21, D58, and D59 were compared,
where a different mixture ratio of the carbon-coated composite
particle to the total amount of the carbon-coated composite
particle and the carbon material was applied to each embodiment. In
Embodiments D17 to D21, where the compositions of the carbon-coated
composite particle fell within the range of 1 to 30 wt. %, the
initial capacities were large and the capacity retention ratios
were high, too. Meanwhile, in Embodiment D58, where the composition
of the carbon-coated composite particle was 0.5 wt. %, the content
of the SiO particle highly capable of absorbing lithium was too
small to attain a sufficient initial capacity for a battery; and in
Embodiment D59, where the composition of the carbon-coated
composite particle stood at 35 wt. %, the expansion/contraction of
the negative electrode plate was so large that the current
collection performance was caused to be deteriorated and the
capacity retention ratio became significantly low. Therefore, for
the enhancement of both initial capacity and capacity retention
ratio, it is preferable that the composition of the carbon-coated
composite particle in the total amount of the carbon-coated
composite particle and the carbon material lie in the range of 1 to
30 wt. %.
[0245] Next, Embodiments D22 to D27 were compared; where a
different mixture ratio of the carbon on the composite particle,
which was prepared using SiO particle and graphite of a scale-like
shape, to the total amount of the carbon on the composite particle,
the SiO particle, and the graphite of a scale-like shape was
applied to each embodiment. In Embodiments D23 to D26, where the
compositions of the carbon fell within the range of 1 to 30 wt. %,
large initial capacities and high capacity retention ratios were
attained. Meanwhile, in Embodiment D22, where the composition of
the carbon was 0.5 wt. %, the capacity retention ratio was rather
low, and in Embodiment D27, where the composition of the carbon was
40 wt. %, the content of the SiO particle highly capable of
absorbing lithium was small, so that the initial capacity was
rather small. Therefore, it is preferable that the composition of
the carbon on the composite particle in the total amount of the
carbon on the composite particle, the SiO particle, and the
graphite of a scale-like shape lie in the range of 1 to 30 wt.
%.
[0246] Next, Embodiments D19, and D28 to D32 were compared, where a
different mixture composition of SiO particle in the total amount
of the SiO particle and the graphite of a scale-like shape was
applied to each embodiment. In Embodiments D19, and D29 to D31,
where the compositions of SiO particle fell within the range of 20
to 70 wt. %, large initial capacities and high capacity retention
ratios were attained. Meanwhile, in Embodiment D28, where the
composition of the SiO particle was 10 wt. %, the content of the
SiO particle highly capable of absorbing lithium was small, so that
the initial capacity became small, and in Embodiment D32, where the
composition of the SiO particle was 80 wt. %, the influence of the
SiO particle on the volume expansion/contraction during the
charge/discharge was so large as to cause a small decrease in the
capacity retention ratio. Therefore, it is preferable that the
composition of the SiO particle in the total amount of the SiO
particle and the graphite of a scale-like shape lie in the range of
20 to 70 wt. %.
[0247] Next, Embodiments D2, and D33 to D37 were compared; where
the number average particle size of the carbon-coated composite
particle was varied. In Embodiments D2, and D34 to D36, where the
number average particle sizes were in the range of 0.1 to 30 .mu.m,
large initial capacities and high capacity retention ratios were
attained. Meanwhile, in Embodiment D33, where the number average
particle size was 0.05 .mu.m, it was difficult to prepare and
handle the active material, so that the capacity retention ratio
became rather small. In Embodiment D37, in addition, where the
number average particle size was 401 .mu.m, the negative electrode
plate was hard to be prepared, and the capacity retention ratio
became rather small. Therefore, it is more preferable that the
number average particle size of the carbon-coated composite
particle lie in the range of 0.1 to 30 .mu.m.
[0248] Hereinafter, the results will be compared in terms of the
process of preparing the composite particle, or the composition of
the carbon material in the negative active materials.
[0249] Embodiments D38 to D40 were compared; where mechanical
milling method was employed for coating the surface of SiO particle
with carbon, and the composition of the carbon material to be mixed
with such carbon-coated SiO particle was varied. In the comparison
of Embodiment D38 with Embodiment D5, where CVD method was employed
for coating the surface of SiO particle with carbon, large initial
capacities were attained in both methods; however, a larger
capacity retention ratio was obtained by using CVD method in
Embodiment D5. It is believed that the reason for this may be that
the surface can be coated more uniformly by the use of CVD method.
In the comparison between Embodiment D38, where MCMB was contained
in the carbon material, and Embodiment D39, where boron-containing
meso carbon fiber was contained in the carbon material, large
initial capacities and high capacity retention ratios were obtained
in both batteries. However, in Embodiment 40, where natural
graphite and artificial graphite, with no MCMB, were used as the
carbon material, the capacity retention ratio became rather
low.
[0250] In addition, Embodiments D41 to D43 were compared. In
Embodiments D41 and D42, where Si and ZrSi.sub.2 were used
respectively as the silicon-containing material, in stead of SiO,
large initial capacities and high capacity retention ratios were
attained. Moreover, in Embodiment D43, where amorphous single-phase
SiO was used as the silicon-containing material, a large initial
capacity and a high capacity retention ratio were obtained. Thus,
when SiO disproportionated to microcrystalline Si and amorphous
SiO.sub.2, and when a diffraction peak appeared in a range of
diffraction angle (2.theta.) from 46.degree. to 49.degree. and the
half width of the main diffraction peak appearing in said range was
smaller than 3.degree. (2.theta.) in X-ray diffraction pattern with
the use of the CuK.alpha. radiation, large initial capacities and
extremely high capacity retention ratios were achieved.
[0251] Finally, the results will be compared in terms of the
following case: as a core material, composite particle was prepared
by mixing SiO particle (S) and graphite of a scale-like shape; the
surface of the composite particle was coated with cupper (Cu) or
nickel (Ni); and the mixture ratio of the Cu or Ni on the composite
particle to the total amount of the Cu or Ni on the composite
particle, the SiO particle, and the graphite of a scale-like shape
was varied.
[0252] Embodiments D44 to D49 were compared, where Cu was used as
coating material. In Embodiments D45 to D48, where the compositions
of the Cu on the composite particle fell within the range of 1 to
30 wt. %, large initial capacities and high capacity retention
ratios were attained. Meanwhile, in Embodiment D44, where the
composition of the Cu was 0.5 wt. %, the capacity retention ratio
became rather low, and in Embodiment D49, where the composition of
the Cu was 40 wt. %, the content of the SiO particle highly capable
of absorbing lithium was small, so that the initial capacity became
rather small. Therefore, it is preferable that the composition of
the Cu on the composite particle in the total amount of the Cu on
the composite particle, the SiO particle, and the graphite of a
scale-like shape lie in the range of 1 to 30 wt. %.
[0253] In the comparison among Embodiments D50 to D55, where Ni was
used as the coating material, similar results to those in the case
where Cu was used were obtained in the relationship of the coating
amount to the initial capacity and the capacity retention ratio. In
addition, the results were consistent with those obtained in
Embodiments D22 to D27, where carbon was used as the coating
material.
Embodiment E
Embodiment E1
[0254] The surface of Si particle (s) was supported with carbon, as
the electronic conductive additive (B), using the method (CVD) of
thermally decomposing toluene gas under argon atmosphere at
1000.degree. C., so that composite particle (e1) was prepared. The
proportion of the electronic conductive additive (B) was determined
to be 0.5 wt. % to the total mass of the composite particle (e1).
The number average particle size of the product (e1) was 10
.mu.m.
[0255] Next, with the use of such composite particle (e1), a
non-aqueous electrolyte secondary battery was produced according to
the following manner. First, 95.5 wt. % of the composite particle
(e1) and, as the carbon material (D), 0.5 wt. % of artificial
graphite were mixed together to prepare a negative active material.
97 wt. % of the obtained negative active material, 2 wt. % of
styrene-butadiene rubber (SBR), and 1 wt. % of
carboxymethyl-cellulose (CMC) were mixed in water to prepare a
paste. The obtained paste was applied to a copper foil having a
thickness of 15 .mu.m so that the total amount of the negative
active material to be housed in the battery could be 2.0 g, and
then dried at 150.degree. C. to evaporate water. This process was
performed on both sides of the copper foil, which then compressed
and molded by roll pressing. Thus, a negative electrode having the
negative composite layer on either side was prepared.
[0256] Next, 90 wt. % of lithium cobalt oxide, 5 wt. % of acetylene
black, and 5 wt. % of poly(vinylidene fluoride) (PVdF) were
dispersed in NMP to make a paste. The obtained paste was applied to
an aluminum foil having a thickness of 20 .mu.m so that the total
amount of the positive active material to be housed in the battery
could be 5.3 g, and then dried at 150.degree. C. to evaporate NMP.
The above-described process was performed on both sides of the
aluminum foil, which then compressed and molded by roll pressing.
Thus, a positive electrode having the positive composite layer on
either side was prepared.
[0257] The positive and negative electrodes thus prepared were
overlapped and wound with a polyethylene separator, with continuous
porosity having a thickness of 20 .mu.m and a porosity of 40%,
being placed between them, and this element was housed in the case
having 48 mm in height, 30 mm in width, and 4.2 mm in thickness to
form a prismatic-type battery having a rated capacity of 700 mA.
Finally, the case was filled with a non-aqueous electrolyte
solution; thus Battery (A1) of Embodiment 1 was completed. The
non-aqueous electrolyte solution was prepared as follows: ethylene
carbonate (EC) and diethyl carbonate (DEC) were mixed together in a
volume ratio of 1:1, and 1 mol dm.sup.-2 of LiPF.sub.6 was
dissolved in the mixed solvent thus prepared.
Embodiment E2
[0258] The surface of Si particle (s) was supported with carbon, as
the electronic conductive additive (B), using the method (CVD) of
thermally decomposing benzene gas under argon atmosphere at
1000.degree. C., so that composite particle (e2) was prepared. The
proportion of the electronic conductive additive (B) was determined
to be 5.0 wt. % to the total mass of the composite particle (e2).
The number average particle size of the composite particle (e2) was
10.9 .mu.m. Except for using such composite particle (e2), Battery
(A2) has an identical configuration to that of Embodiment E1. This
battery was termed Embodiment E2.
Embodiment E3
[0259] The surface of Si particle (s) was supported with carbon, as
the electronic conductive additive (B), using the method (CVD) of
thermally decomposing benzene gas under argon atmosphere at
1000.degree. C., so that composite particle (e3) was prepared. The
proportion of the electronic conductive additive (B) was determined
to be 10.0 wt. % to the total mass of the composite particle (e3).
The number average particle size of the composite particle (e3) was
11.5 .mu.m. Except for using such composite particle (e3), Battery
(A3) has an identical configuration to that of Embodiment E1. This
battery was termed Embodiment E3.
Embodiment E4
[0260] The surface of Si particle (s) was supported with carbon, as
the electronic conductive additive (B), using the method (CVD) of
thermally decomposing benzene gas under argon atmosphere at
1000.degree. C., so that composite particle (e4) was prepared. The
proportion of the electronic conductive additive (B) was determined
to be 20.0 wt. % to the total mass of the composite particle (e4).
The number average particle size of the composite particle (e4) was
13.0 .mu.m. Except for using such composite particle (e4), Battery
(A4) has an identical configuration to that of Embodiment E1. This
battery was termed Embodiment E4.
Embodiment E5
[0261] The surface of Si particle (s) was supported with carbon, as
the electronic conductive additive (B), using the method (CVD) of
thermally decomposing benzene gas under argon atmosphere at
1000.degree. C., so that composite particle (e5) was prepared. The
proportion of the electronic conductive additive (B) was determined
to be 30.0 wt. % to the total mass of the composite particle (e5).
The number average particle size of the composite particle (e5) was
14.5 .mu.m. Except for using such composite particle (e5), Battery
(A5) has an identical configuration to that of Embodiment E1. This
battery was termed Embodiment E5.
Embodiment E6
[0262] The surface of Si particle (s) was supported with carbon, as
the electronic conductive additive (B), using the method (CVD) of
thermally decomposing benzene gas under argon atmosphere at
1000.degree. C., so that composite particle (e6) was prepared. The
proportion of the electronic conductive additive (B) was determined
to be 38.0 wt. % to the total mass of the composite particle (e6).
The number average particle size of the composite particle (e6) was
16.1 .mu.m. Except for using such composite particle (e6), Battery
(A6) has an identical configuration to that of Embodiment E1. This
battery was termed Embodiment E6.
Embodiment E7
[0263] The surface of Si particle (s) was supported with carbon, as
the electronic conductive additive (B), using the method (CVD) of
thermally decomposing benzene gas under argon atmosphere at
1000.degree. C., so that a product (e7) was prepared. The
proportion of the electronic conductive additive (B) was determined
to be 40.0 wt. % to the total mass of the product (e7). The number
average particle size of the product (e7) was 16.4 .mu.m. Except
for using this product (e7), Battery (A7) has an identical
configuration to that of Embodiment E1. This battery was termed
Embodiment E7.
Comparative Example E1
[0264] The surface of Si particle (s) was supported with carbon, as
the electronic conductive additive (B), using the method (CVD) of
thermally decomposing benzene gas under argon atmosphere at
1000.degree. C., so that a product (e8) was prepared. The
proportion of the electronic conductive additive (B) was determined
to be 0.1 wt. % to the total mass of the product (e8). The number
average particle size of the product (e8) was 9.8 .mu.m. Except for
using this product (e8), Battery (B1) has an identical
configuration to that of Embodiment E1. This battery was termed
Comparative Example E1.
Embodiment E153
[0265] The surface of Si particle (s) was supported with carbon, as
the electronic conductive additive (B), using the method (CVD) of
thermally decomposing benzene gas under argon atmosphere at
10000.degree. C., so that a product (e9) was prepared. The
proportion of the electronic conductive additive (B) was determined
to be 50.0 wt. % to the total mass of the product (e9). The number
average particle size of the product (e9) was 18.1 .mu.m. Except
for using this product (e9), Battery (B2) has an identical
configuration to that of Embodiment E1. This battery was termed
Embodiment E153.
Embodiment E8
[0266] 80.0 wt. % of the product (e1) and, as the carbon material
(D), 20.0 wt. % of artificial graphite were mixed together to
prepare a negative active material. Except for the above, Battery
(A8) has an identical configuration to that of Embodiment E1. This
battery was termed Embodiment E8.
Embodiments E9 to 14
[0267] Except for using the product (e2), Battery (A9) has an
identical configuration to that of Embodiment E8. This battery was
termed Embodiment E9. Except for using the product (e3), Battery
(A10) has an identical configuration to that of Embodiment E8. This
battery was termed Embodiment E10. Except for using the product
(e4), Battery (A11) has an identical configuration to that of
Embodiment E8. This battery was termed Embodiment E11. Except for
using the product. (e5), Battery (A12) has an identical
configuration to that of Embodiment E8. This battery was termed
Embodiment E12. Except for using the product (e6), Battery (A13)
has an identical configuration to that of Embodiment E8. This
battery was termed Embodiment E13. And, except for using the
product (e7), Battery (A14) has an identical configuration to that
of Embodiment E8. This battery was termed Embodiment E14.
Comparative Example E2
[0268] Except for using the product (e8), Battery (B3) has an
identical configuration to that of Embodiment E8. This battery was
termed Comparative Example E2.
Embodiment E154
[0269] Except for using the product (e9), Battery (B4) has an
identical configuration to that of Embodiment E8. This battery was
termed Embodiment E154.
Embodiment E15
[0270] 99.9 wt. % of the product (e1) and, as the carbon material
(D), 0.1 wt. % of artificial graphite were mixed together to
prepare a negative active material. Except for the above, Battery
(A15) has an identical configuration to that of Embodiment E1. This
battery was termed Embodiment E15.
Embodiment E16
[0271] 99.0 wt. % of the product (e1) and, as the carbon material
(D), 1.0 wt. % of artificial graphite were mixed together to
prepare a negative active material. Except for the above, Battery
(A16) has an identical configuration to that of Embodiment E1. This
battery was termed Embodiment E16.
Embodiment E17
[0272] 95.0 wt. % of the product (e1) and, as the carbon material
(D), 5.0 wt. % of artificial graphite were mixed together to
prepare a negative active material. Except for the above, Battery
(A17) has an identical configuration to that of Embodiment E1. This
battery was termed Embodiment E17.
Embodiment E18
[0273] 90.0 wt. % of the product (e1) and, as the carbon material
(D), 10.0 wt. % of artificial graphite were mixed together to
prepare a negative active material. Except for the above, Battery
(A18) has an identical configuration to that of Embodiment E1. This
battery was termed Embodiment E18.
Embodiment E19
[0274] 85.0 wt. % of the product (e1) and, as the carbon material
(D), 15.0 wt. % of artificial graphite were mixed together to
prepare a negative active material. Except for the above, Battery
(A19) has an identical configuration to that of Embodiment E1. This
battery was termed Embodiment E19.
Embodiment E20
[0275] 75.0 wt. % of the product (e1) and, as the carbon material
(D), 25.0 wt. % of artificial graphite were mixed together to
prepare a negative active material. Except for the above, Battery
(A20) has an identical configuration to that of Embodiment E1. This
battery was termed Embodiment E20.
Embodiment E21
[0276] 99.9 wt. % of the product (e4) and, as the carbon material
(D), 0.1 wt. % of artificial graphite were mixed together to
prepare a negative active material. Except for the above, Battery
(A21) has an identical configuration to that of Embodiment E1. This
battery was termed Embodiment E21.
Embodiment E22
[0277] 99.0 wt. % of the product (e4) and, as the carbon material
(D), 1.0 wt. % of artificial graphite were mixed together to
prepare a negative active material. Except for the above, Battery
(A22) has an identical configuration to that of Embodiment E1. This
battery was termed Embodiment E22.
Embodiment E23
[0278] 95.0 wt. % of the product (e4) and, as the carbon material
(D), 5.0 wt. % of artificial graphite were mixed together to
prepare a negative active material. Except for the above, Battery
(A23) has an identical configuration to that of Embodiment E1. This
battery was termed Embodiment E23.
Embodiment E24
[0279] 90.0 wt. % of the product (e4) and, as the carbon material
(D), 10.0 wt. % of artificial graphite were mixed together to
prepare a negative active material. Except for the above, Battery
(A24) has an identical configuration to that of Embodiment E1. This
battery was termed Embodiment E24.
Embodiment E25
[0280] 85.0 wt. % of the product (e4) and, as the carbon material
(D), 15.0 wt. % of artificial graphite were mixed together to
prepare a negative active material. Except for the above, Battery
(A25) has an identical configuration to that of Embodiment E1. This
battery was termed Embodiment E25.
Embodiment E26
[0281] 75.0 wt. % of the product (e4) and, as the carbon material
(D), 25.0 wt. % of artificial graphite were mixed together to
prepare a negative active material. Except for the above, Battery
(A26) has an identical configuration to that of Embodiment E1. This
battery was termed Embodiment E26.
Embodiment E27
[0282] 99.9 wt. % of the product (e7) and, as the carbon material
(D), 0.1 wt. % of artificial graphite were-mixed together to
prepare a negative active material. Except for the above, Battery
(A27) has an identical configuration to that of Embodiment E1. This
battery was termed Embodiment E27.
Embodiment E28
[0283] 99.0 wt. % of the product (e7) and, as the carbon material
(D), 1.0 wt. % of artificial graphite were mixed together to
prepare a negative active material. Except for the above, Battery
(A28) has an identical configuration to that of Embodiment E1. This
battery was termed Embodiment E28.
Embodiment E29
[0284] 95.0 wt. % of the product (e7) and, as the carbon material
(D), 5.0 wt. % of artificial graphite were mixed together to
prepare a negative active material. Except for the above, Battery
(A29) has an identical configuration to that of Embodiment E1. This
battery was termed Embodiment E29.
Embodiment E30
[0285] 90.0 wt. % of the product (e7) and, as the carbon material
(D), 10.0 wt. % of artificial graphite were mixed together to
prepare a negative active material. Except for the above, Battery
(A30) has an identical configuration to that of Embodiment E1. This
battery was termed Embodiment E30.
Embodiment E31
[0286] 85.0 wt. % of the product (e7) and, as the carbon material
(D), 15.0 wt. % of artificial graphite were mixed together to
prepare a negative active material. Except for the above, Battery
(A31) has an identical configuration to that of Embodiment E1. This
battery was termed Embodiment E31.
Embodiment E32
[0287] 75.0 wt. % of the product (e7) and, as the carbon material
(D), 25.0 wt. % of artificial graphite were mixed together to
prepare a negative active material. Except for the above, Battery
(A32) has an identical configuration to that of Embodiment E1. This
battery was termed Embodiment E32.
Embodiment E33
[0288] By mechanochemical reaction between Si particle (s) and
artificial graphite, as the carbon material (E), a composite was
prepared. The surface of such composite was supported with carbon,
as the electronic conductive additive (B), using the method (CVD)
of thermally decomposing toluene gas under argon atmosphere at
1000.degree. C., so that a product (e10) was prepared. The
proportions of the electronic conductive additive (B) and the
carbon material (E) were determined to be 0.5 wt. % and 59.5 wt. %,
respectively, to the total mass of the product (e10). The number
average particle size of the product (e10) was 15 .mu.m.
[0289] Except for using the product (e10), Battery (A33) has an
identical configuration to that of Embodiment E1. This battery was
termed Embodiment E33.
Embodiment E34
[0290] By mechanochemical reaction between Si particle (s) and
artificial graphite, as the carbon material (E), a composite was
prepared. The surface of such composite was supported with carbon,
as the electronic conductive additive (B), using the method (CVD)
of thermally decomposing toluene gas under argon atmosphere at
1000.degree. C., so that a product (e11) was prepared. The
proportions of the electronic conductive additive (B) and the
carbon material (E) were determined to be 5.0 wt. % and 59.0 wt. %,
respectively, to the total mass of the product (e11). The number
average particle size of the product (e11) was 15.5 .mu.m.
[0291] Except for using the product (e11), Battery (A34) has an
identical configuration to that of Embodiment E1. This battery was
termed Embodiment E34.
Embodiment E35
[0292] By mechanochemical reaction between Si particle (s) and
artificial graphite, as the carbon material (E), a composite was
prepared. The surface of such composite was supported with carbon,
as the electronic conductive additive (B), using the method (CVD)
of thermally decomposing toluene gas under argon atmosphere at
1000.degree. C., so that a product (e12) was prepared. The
proportions of the electronic conductive additive (B) and the
carbon material (E) were determined to be 10.0 wt. % and 50.0 wt.
%, respectively, to the total mass of the product (e12). The number
average particle size of the product (e12) was 16.1 .mu.m.
[0293] Except for using the product (e12), Battery (A35) has an
identical configuration to that of Embodiment E1. This battery was
termed Embodiment E35.
Embodiment E36
[0294] By mechanochemical reaction between Si particle (s) and
artificial graphite, as the carbon material (E), a composite was
prepared. The surface of such composite was supported with carbon,
as the electronic conductive additive (B), using the method (CVD)
of thermally decomposing toluene gas under argon atmosphere at
1000.degree. C., so that a product (e13) was prepared. The
proportions of the electronic conductive additive (B) and the
carbon material (E) were determined to be 20.0 wt. % and 40.0 wt.
%, respectively, to the total mass of the product (e13). The number
average particle size of the product (e13) was 17.2 .mu.m.
[0295] Except for using the product (e13), Battery (A36) has an
identical configuration to that of Embodiment E1. This battery was
termed Embodiment E36.
Embodiment E37
[0296] By mechanochemical reaction between Si particle (s) and
artificial graphite, as the carbon material (E), a composite was
prepared. The surface of such composite was supported with carbon,
as the electronic conductive additive (B), using the method (CVD)
of thermally decomposing toluene gas under argon atmosphere at
1000.degree. C., so that a product (e14) was prepared. The
proportions of the electronic conductive additive (B) and the
carbon material (E) were determined to be 30.0 wt. % and 30.0 wt.
%, respectively, to the total mass of the product (e14). The number
average particle size of the product (e14) was 18.1 .mu.m.
[0297] Except for using the product (e14), Battery (A37) has an
identical configuration to that of Embodiment E1. This battery was
termed Embodiment E37.
Embodiment E38
[0298] By mechanochemical reaction between Si particle (s) and
artificial graphite, as the carbon material (E), a composite was
prepared. The surface of such composite was supported with carbon,
as the electronic conductive additive (B), using the method (CVD)
of thermally decomposing toluene gas under argon atmosphere at
1000.degree. C., so that a product (e15) was prepared. The
proportions of the electronic conductive additive (B) and the
carbon material (E) were determined to be 38.0 wt. % and 22.0 wt.
%, respectively, to the total mass of the product (e15). The number
average particle size of the product (e15) was 19.5 .mu.m.
[0299] Except for using the product (e15), Battery (A38) has an
identical configuration to that of Embodiment E1. This battery was
termed Embodiment E38.
Embodiment E39
[0300] By mechanochemical reaction between Si particle (s) and
artificial graphite, as the carbon material (E), a composite was
prepared. The surface of such composite was supported with carbon,
as the electronic conductive additive (B), using the method (CVD)
of thermally decomposing toluene gas under argon atmosphere at
1000.degree. C., so that a product (e16) was prepared. The
proportions of the electronic conductive additive (B) and the
carbon material (E) were determined to be 40.0 wt. % and 20.0 wt.
%, respectively, to the total mass of the product (e16). The number
average particle size of the product (e16) was 20.4 .mu.m.
[0301] Except for using the product (e16), Battery (A39) has an
identical configuration to that of Embodiment E1. This battery was
termed Embodiment E39.
Comparative Example E3
[0302] By mechanochemical reaction between Si particle (s) and
artificial graphite, as the carbon material (E), a composite was
prepared. The surface of such composite was supported with carbon,
as the electronic conductive additive (B), using the method (CVD)
of thermally decomposing toluene gas under argon atmosphere at
1000.degree. C., so that a product (e17) was prepared. The
proportions of the electronic conductive additive (B) and the
carbon material (E) were determined to be 0.1 wt. % and 59.9 wt. %,
respectively, to the total mass of the product (e17). The number
average particle size of the product (e17) was 14.81 .mu.m.
[0303] Except for using the product (e17), Battery (B5) has an
identical configuration to that of Embodiment E1. This battery was
termed Comparative Example E3.
Embodiment E155
[0304] By mechanochemical reaction between Si particle (s) and
artificial graphite, as the carbon material (E), a composite was
prepared. The surface of such composite was supported with carbon,
as the electronic conductive additive (B), using the method (CVD)
of thermally decomposing toluene gas under argon atmosphere at
1000.degree. C., so that a product (e18) was prepared. The
proportions of the electronic conductive additive (B) and the
carbon material (E) were determined to be 50.0 wt. % and 10.0 wt.
%, respectively, to the total mass of the product (e18). The number
average particle size of the product (e18) was 21.5 .mu.m.
[0305] Except for using the product (e18), Battery (B6) has an
identical configuration to that of Embodiment E1. This battery was
termed Embodiment E155.
Embodiment E40
[0306] 80.0 wt. % of the product (e10) and, as the carbon material
(D), 20.0 wt. % of artificial graphite were mixed together to
prepare a negative active material. Except for the above, Battery
(A40) has an identical configuration to that of Embodiment E1. This
battery was termed Embodiment E40.
Embodiment E41
[0307] Except for using the product (e11), Battery (A41) has an
identical configuration to that of Embodiment E40. This battery was
termed Embodiment E41.
Embodiment E42
[0308] Except for using the product (e12), Battery (A42) has an
identical configuration to that of Embodiment E40. This battery was
termed Embodiment E42.
Embodiment E43
[0309] Except for using the product (e13), Battery (A43) has an
identical configuration to that of Embodiment E40. This battery was
termed Embodiment E43.
Embodiment E44
[0310] Except for using the product (e14), Battery (A44) has an
identical configuration to that of Embodiment E40. This battery was
termed Embodiment E44.
Embodiment E45
[0311] Except for using the product (e15), Battery (A45) has an
identical configuration to that of Embodiment E40. This battery was
termed Embodiment E45.
Embodiment E46
[0312] Except for using the product (e16), Battery (A46) has an
identical configuration to that of Embodiment E40. This battery was
termed Embodiment E46.
Comparative Example E4
[0313] Except for using the product (e17), Battery (B7) has an
identical configuration to that of Embodiment E40. This battery was
termed Comparative Example E4.
Embodiment E156
[0314] Except for using the product (e18), Battery (B7) has an
identical configuration to that of Embodiment E40. This battery was
termed Embodiment E156.
Embodiment E47
[0315] 99.9 wt. % of the product (e10) and, as the carbon material
(D), 0.1 wt. % of artificial graphite were mixed together to
prepare a negative active material. Except for the above, Battery
(A47) has an identical configuration to that of Embodiment E1. This
battery was termed Embodiment E47.
Embodiment E48
[0316] 99.0 wt. % of the product (e10) and, as the carbon material
(D), 1.0 wt. % of artificial graphite were mixed together to
prepare a negative active material. Except for the above, Battery
(A48) has an identical configuration to that of Embodiment E1. This
battery was termed Embodiment E48.
Embodiment E49
[0317] 95.0 wt. % of the product (e10) and, as the carbon material
(D), 5.0 wt. % of artificial graphite were mixed together to
prepare a negative active material. Except for the above, Battery
(A49) has an identical configuration to that of Embodiment E1. This
battery was termed Embodiment E49.
Embodiment E50
[0318] 90.0 wt. % of the product (e10) and, as the carbon material
(D), 10.0 wt. % of artificial graphite were mixed together to
prepare a negative active material. Except for the above, Battery
(A50) has an identical configuration to that of Embodiment E1. This
battery was termed Embodiment E50.
Embodiment E51
[0319] 85.0 wt. % of the product (e10) and, as the carbon material
(D), 15.0 wt. % of artificial graphite were mixed together to
prepare a negative active material. Except for the above, Battery
(A51) has an identical configuration to that of Embodiment E1. This
battery was termed Embodiment E51.
Embodiment E52
[0320] 75.0 wt. % of the product (e10) and, as the carbon material
(D), 25.0 wt. % of artificial graphite were mixed together to
prepare a negative active material. Except for the above, Battery
(A52) has an identical configuration to that of Embodiment E1. This
battery was termed Embodiment E52.
Embodiment E53
[0321] 99.9 wt. % of the product (e13) and, as the carbon material
(D), 0.1 wt. % of artificial graphite were mixed together to
prepare a negative active material. Except for the above, Battery
(A53) has an identical configuration to that of Embodiment E1. This
battery was termed Embodiment E53.
Embodiment E54
[0322] 99.0 wt. % of the product (e13) and, as the carbon material
(D), 1.0 wt. % of artificial graphite were mixed together to
prepare a negative active material. Except for the above, Battery
(A54) has an identical configuration to that of Embodiment E1. This
battery was termed Embodiment E54.
Embodiment E55
[0323] 95.0 wt. % of the product (e13) and, as the carbon material
(D), 5.0 wt. % of artificial graphite were mixed together to
prepare a negative active material. Except for the above, Battery
(A55) has an identical configuration to that of Embodiment E1. This
battery was termed Embodiment E55.
Embodiment E56
[0324] 90.0 wt. % of the product (e13) and, as the carbon material
(D), 10.0 wt. % of artificial graphite were mixed together to
prepare a negative active material. Except for the above, Battery
(A56) has an identical configuration to that of Embodiment E1. This
battery was termed Embodiment E56.
Embodiment E57
[0325] 85.0 wt. % of the product (e13) and, as the carbon material
(D), 15.0 wt. % of artificial graphite were mixed together to
prepare a negative active material. Except for the above, Battery
(A57) has an identical configuration to that of Embodiment E1. This
battery was termed Embodiment E57.
Embodiment E58
[0326] 75.0 wt. % of the product (e13) and, as the carbon material
(D), 25.0 wt. % of artificial graphite were mixed together to
prepare a negative active material. Except for the above, Battery
(A58) has an identical configuration to that of Embodiment E1. This
battery was termed Embodiment E58.
Embodiment E59
[0327] 99.9 wt. % of the product (e16) and, as the carbon material
(D), 0.1 wt. % of artificial graphite were mixed together to
prepare a negative active material. Except for the above, Battery
(A59) has an identical configuration to that of Embodiment E1. This
battery was termed Embodiment E59.
Embodiment E60
[0328] 99.0 wt. % of the product (e16) and, as the carbon material
(D), 1.0 wt. % of artificial graphite were mixed together to
prepare a negative active material. Except for the above, Battery
(A60) has an identical configuration to that of Embodiment E1. This
battery was termed Embodiment E60.
Embodiment E61
[0329] 95.0 wt. % of the product (e16) and, as the carbon material
(D), 5.0 wt. % of artificial graphite were mixed together to
prepare a negative active material. Except for the above, Battery
(A61) has an identical configuration to that of Embodiment E1. This
battery was termed Embodiment E61.
Embodiment E62
[0330] 90.0 wt. % of the product (e16) and, as the carbon material
(D), 10.0 wt. % of artificial graphite were mixed together to
prepare a negative active material. Except for the above, Battery
(A62) has an identical configuration to that of Embodiment E1. This
battery was termed Embodiment E62.
Embodiment E63
[0331] 85.0 wt. % of the product (e16) and, as the carbon material
(D), 15.0 wt. % of artificial graphite were mixed together to
prepare a negative active material. Except for the above, Battery
(A63) has an identical configuration to that of Embodiment E1. This
battery was termed Embodiment E63.
Embodiment E64
[0332] 75.0 wt. % of the product (e16) and, as the carbon material
(D), 25.0 wt. % of artificial graphite were mixed together to
prepare a negative active material. Except for the above, Battery
(A64) has an identical configuration to that of Embodiment E1. This
battery was termed Embodiment E64.
Embodiment E65
[0333] The surface of SiO particle (t) was supported with carbon,
as the electronic conductive additive (B), using the method (CVD)
of thermally decomposing toluene gas under argon atmosphere at
1000.degree. C., so that a product (e17) was prepared. The
proportion of the electronic conductive additive (B) was determined
to be 0.5 wt. % to the total mass of the product (e17). The number
average particle size of the product (e17) was 0.9 .mu.m.
[0334] 30 wt. % of the product (e17) and, as the carbon material
(D), 40 wt. % of meso carbon microbeads, 10 wt. % of natural
graphite and 20 wt. % of artificial graphite were mixed together to
prepare a negative active material. Except for the above, Battery
(A65) has an identical configuration to that of Embodiment E1. This
battery was termed Embodiment E65.
Embodiment E66
[0335] The surface of SiO particle (t) was supported with carbon,
as the electronic conductive additive (B), using the method (CVD)
of thermally decomposing toluene gas under argon atmosphere at
1000.degree. C., so that a product (e18) was prepared. The
proportion of the electronic conductive additive (B) was determined
to be 1.0 wt. % to the total mass of the product (e18). The number
average particle size of the product (e18) was 0.9 .mu.m.
[0336] Except for using this product (e18), Battery (A66) has an
identical configuration to that of Embodiment E65. This battery was
termed Embodiment E66.
Embodiment E67
[0337] The surface of SiO particle (t) was supported with carbon,
as the electronic conductive additive (B), using the method (CVD)
of thermally decomposing toluene gas under argon atmosphere at
1000.degree. C., so that a product (e19) was prepared. The
proportion of the electronic conductive additive (B) was determined
to be 10.0 wt. % to the total mass of the product (e19). The number
average particle size of the product (e19) was 1.0 .mu.m.
[0338] Except for using this product (e19), Battery (A67) has an
identical configuration to that of Embodiment E65. This battery was
termed Embodiment E67.
Embodiment E68
[0339] The surface of SiO particle (t) was supported with carbon,
as the electronic conductive additive (B), using the method (CVD)
of thermally decomposing toluene gas under argon atmosphere at
100.degree. C., so that a product (e20) was prepared. The
proportion of the electronic conductive additive (B) was determined
to be 20.0 wt. % to the total mass of the product (e20). The number
average particle size of the product (e20) was 1.0 .mu.m.
[0340] Except for using this product-(e20), Battery (A68) has an
identical configuration to that of Embodiment E65. This battery was
termed Embodiment E68.
Embodiment E69
[0341] The surface of SiO particle (t) was supported with carbon,
as the electronic conductive additive (B), using the method (CVD)
of thermally decomposing toluene gas under argon atmosphere at
1000.degree. C., so that a product (e21) was prepared. The
proportion of the electronic conductive additive (B) was determined
to be 30.0 wt. % to the total mass of the product (e21). The number
average particle size of the product (e21) was 1.1 .mu.m.
[0342] Except for using this product (e21), Battery (A69) has an
identical configuration to that of Embodiment E65. This battery was
termed Embodiment E69.
Embodiment E70
[0343] The surface of SiO particle (t) was supported with carbon,
as the electronic conductive additive (B), using the method (CVD)
of thermally decomposing toluene gas under argon atmosphere at
1000.degree. C., so that a product (e22) was prepared. The
proportion of the electronic conductive additive (B) was determined
to be 38.0 wt. % to the total mass of the product (e22). The number
average particle size of the product (e22) was 1.2 .mu.m.
[0344] Except for using this product (e22), Battery (A70) has an
identical configuration to that of Embodiment E65. This battery was
termed Embodiment E70.
Embodiment E71
[0345] The surface of SiO particle (t) was supported with carbon,
as the electronic conductive additive (B), using the method (CVD)
of thermally decomposing toluene gas under argon atmosphere at
1000.degree. C., so that a product (e23) was prepared. The
proportion of the electronic conductive additive (B) was determined
to be 40.0 wt. % to the total mass of the product (e23). The number
average particle size of the product (e23) was 1.41 .mu.m.
[0346] Except for using this product (e23), Battery (A71) has an
identical configuration to that of Embodiment E65. This battery was
termed Embodiment E71.
Comparative Example E5
[0347] The surface of SiO particle (t) was supported with carbon,
as the electronic conductive additive (B), using the method (CVD)
of thermally decomposing toluene gas under argon atmosphere at
1000.degree. C., so that a product (e24) was prepared. The
proportion of the electronic conductive additive (B) was determined
to be 0.1 wt. % to the total mass of the product (e24). The number
average particle size of the product (e24) was 0.8 .mu.m.
[0348] Except for using this product (e24), Battery (B9) has an
identical configuration to that of Embodiment E65. This battery was
termed Comparative Example E5.
Embodiment E157
[0349] The surface of SiO particle (t) was supported with carbon,
as the electronic conductive additive (B), using the method (CVD)
of thermally decomposing toluene gas under argon atmosphere at
1000.degree. C., so that a product (e25) was prepared. The
proportion of the electronic conductive additive (B) was determined
to be 50.0 wt. % to the total mass of the product (e25). The number
average particle size of the product (e25) was 1.5 .mu.m.
[0350] Except for using this product (e25), Battery (B10) has an
identical configuration to that of Embodiment E65. This battery was
termed Embodiment E157.
Embodiment E72
[0351] 10 wt. % of the product (e17) and, as the carbon material
(D), 40 wt. % of meso carbon microbeads, 30 wt. % of natural
graphite and 20 wt. % of artificial graphite were mixed together to
prepare a negative active material. Except for the above, Battery
(A72) has an identical configuration to that of Embodiment E1. This
battery was termed Embodiment E72.
Embodiment E73
[0352] Except for using the product (e18), Battery (A73) has an
identical configuration to that of Embodiment E72. This battery was
termed Embodiment E73.
Embodiment E74
[0353] Except for using the product (e19), Battery (A74) has an
identical configuration to that of Embodiment E72. This battery was
termed Embodiment E74.
Embodiment E75
[0354] Except for using the product (e20), Battery (A75) has an
identical configuration to that of Embodiment E72. This battery was
termed Embodiment E75.
Embodiment E76
[0355] Except for using the product (e21), Battery (A76) has an
identical configuration to that of Embodiment E72. This battery was
termed Embodiment E76.
Embodiment E77
[0356] Except for using the product (e22), Battery (A77) has an
identical configuration to that of Embodiment E72. This battery was
termed Embodiment E77.
Embodiment E78
[0357] Except for using the product (e23), Battery (A78) has an
identical configuration to that of Embodiment E72. This battery was
termed Embodiment E78.
Comparative Example E6
[0358] Except for using the product (e24), Battery (B11) has an
identical configuration to that of Embodiment E72. This battery was
termed Comparative Example E6.
Embodiment E158
[0359] Except for using the product (e25), Battery (B12) has an
identical configuration to that of Embodiment E72. This battery was
termed Embodiment E158.
Embodiment E79
[0360] 5 wt. % of the product (e17) and, as the carbon material
(D), 40 wt. % of meso carbon microbeads, 35 wt. % of natural
graphite and 20 wt. % of artificial graphite were mixed together to
prepare a negative active material. Except for the above, Battery
(A79) has an identical configuration to that of Embodiment E1. This
battery was termed Embodiment E79.
Embodiment E80
[0361] Except for using the product (e18), Battery (A80) has an
identical configuration to that of Embodiment E79. This battery was
termed Embodiment E80.
Embodiment E81
[0362] Except for using the product (e19), Battery (A81) has an
identical configuration to that of Embodiment E79. This battery was
termed Embodiment E81.
Embodiment E82
[0363] Except for using the product (e20), Battery (A82) has an
identical configuration to that of Embodiment E79. This battery was
termed Embodiment E82.
Embodiment E83
[0364] Except for using the product (e21), Battery (A83) has an
identical configuration to that of Embodiment E79. This battery was
termed Embodiment E83.
Embodiment E84
[0365] Except for using the product (e22), Battery (A84) has an
identical configuration to that of Embodiment E79. This battery was
termed Embodiment E84.
Embodiment E85
[0366] Except for using the product (e23), Battery (A85) has an
identical configuration to that of Embodiment E79. This battery was
termed Embodiment E85.
Comparative Example E7
[0367] Except for using the product (e24), Battery (B13) has an
identical configuration to that of Embodiment E79. This battery was
termed Comparative Example E7.
Embodiment E159
[0368] Except for using the product (e25), Battery (B14) has an
identical configuration to that of Embodiment E79. This battery was
termed Embodiment E159.
Embodiment E86
[0369] 1 wt. % of the product (e17) and, as the carbon material
(D), 40 wt. % of meso carbon microbeads, 39 wt. % of natural
graphite and 20 wt. % of artificial graphite were mixed together to
prepare a negative active material. Except for the above, Battery
(A86) has an identical configuration to that of Embodiment E1. This
battery was termed Embodiment E86.
Embodiment E87
[0370] Except for using the product (e18), Battery (A87) has an
identical configuration to that of Embodiment E86. This battery was
termed Embodiment E87.
Embodiment E88
[0371] Except for using the product (e19), Battery (A88) has an
identical configuration to that of Embodiment E86. This battery was
termed Embodiment E88.
Embodiment E89
[0372] Except for using the product (e20), Battery (A89) has an
identical configuration to that of Embodiment E86. This battery was
termed Embodiment E89.
Embodiment E90
[0373] Except for using the product (e21), Battery (A90) has an
identical configuration to that of Embodiment E86. This battery was
termed Embodiment E90.
Embodiment E91
[0374] Except for using the product (e22), Battery (A91) has an
identical configuration to that of Embodiment E86. This battery was
termed Embodiment E91.
Embodiment E92
[0375] Except for using the product (e23), Battery (A92) has an
identical configuration to that of Embodiment E86. This battery was
termed Embodiment E92.
Comparative Example E8
[0376] Except for using the product (e24), Battery (B15) has an
identical configuration to that of Embodiment E86. This battery was
termed Comparative Example E8.
Embodiment E160
[0377] Except for using the product (e25), Battery (B16) has an
identical configuration to that of Embodiment E86. This battery was
termed Embodiment E160.
Embodiment E93
[0378] 35 wt. % of the product (e17) and, as the carbon material
(D), 40 wt. % of meso carbon microbeads, 5 wt. % of natural
graphite and 20 wt. % of artificial graphite were mixed together to
prepare a negative active material. Except for the above, Battery
(A93) has an identical configuration to that of Embodiment E1. This
battery was termed Embodiment E93.
Embodiment E94
[0379] 20 wt. % of the product (e17) and, as the carbon material
(D), 40 wt. % of meso carbon microbeads, 20 wt. % of natural
graphite and 20 wt. % of artificial graphite were mixed together to
prepare a negative active material. Except for the above, Battery
(A94) has an identical configuration to that of Embodiment E1. This
battery was termed Embodiment E94.
Embodiment E95
[0380] 0.5 wt. % of the product (e17) and, as the carbon material
(D), 40 wt. % of meso carbon microbeads, 35.5 wt. % of natural
graphite and 20 wt. % of artificial graphite were mixed together to
prepare a negative active material. Except for the above, Battery
(A95) has an identical configuration to that of Embodiment E1. This
battery was termed Embodiment E95.
Embodiment E96
[0381] 35 wt. % of the product (e20) and, as the carbon material
(D), 40 wt. % of meso carbon microbeads, 5 wt. % of natural
graphite and 20 wt. % of artificial graphite were mixed together to
prepare a negative active material. Except for the above, Battery
(A96) has an identical configuration to that of Embodiment E1. This
battery was termed Embodiment E96.
Embodiment E97
[0382] 20 wt. % of the product (e20) and, as the carbon material
(D), 40 wt. % of meso carbon microbeads, 20 wt. % of natural
graphite and 20 wt. % of artificial graphite were mixed together to
prepare a negative active material. Except for the above, Battery
(A97) has an identical configuration to that of Embodiment E1. This
battery was termed Embodiment E97.
Embodiment E98
[0383] 0.5 wt. % of the product (e20) and, as the carbon material
(D), 40 wt. % of meso carbon microbeads, 35.5 wt. % of natural
graphite and 20 wt. % of artificial graphite were mixed together to
prepare a negative active material. Except for the above, Battery
(A98) has an identical configuration to that of Embodiment E1. This
battery was termed Embodiment E98.
Embodiment E99
[0384] 35 wt. % of the product (e23) and, as the carbon material
(D), 40 wt. % of meso carbon microbeads, 5 wt. % of natural
graphite and 20 wt. % of artificial graphite were mixed together to
prepare a negative active material. Except for the above, Battery
(A99) has an identical configuration to that of Embodiment E1. This
battery was termed Embodiment E99.
Embodiment E100
[0385] 20 wt. % of the product (e23) and, as the carbon material
(D), 40 wt. % of meso carbon microbeads, 20 wt. % of natural
graphite and 20 wt. % of artificial graphite were mixed together to
prepare a negative active material. Except for the above, Battery
(A100) has an identical configuration to that of Embodiment E1.
This battery was termed Embodiment E100.
Embodiment E101
[0386] 0.5 wt. % of the product (e23) and, as the carbon material
(D), 40 wt. % of meso carbon microbeads, 35.5 wt. % of natural
graphite and 20 wt. % of artificial graphite were mixed together to
prepare a negative active material. Except for the above, Battery
(A101) has an identical configuration to that of Embodiment E1.
This battery was termed Embodiment E101.
Embodiment E102
[0387] The surface of SiO particle (t) was supported with nickel,
as the electronic conductive additive (B), by electroless plating
technique with the use of Ni-801 (Kojundo Chemical Laboratory) as a
plating solution, so that a product (e26) was prepared. The
proportion of the electronic conductive additive (B) was determined
to be 0.5 wt. % to the total mass of the product (e26). The number
average particle size of the product (e26) was 0.91 .mu.m.
[0388] 5 wt. % of the product (e26) and, as the carbon material
(D), 40 wt. % of meso carbon microbeads, 35 wt. % of natural
graphite and 20 wt. % of artificial graphite were mixed together to
prepare a negative active material. Except for the above, Battery
(A102) has an identical configuration to that of Embodiment E1.
This battery was termed Embodiment E102.
Embodiment E103
[0389] The surface of SiO particle (t) was supported with nickel,
as the electronic conductive additive (B), by electroless plating
technique with the use of Ni-801 (Kojundo Chemical Laboratory) as a
plating solution, so that a product (e27) was prepared. The
proportion of the electronic conductive additive (B) was determined
to be 1.0 wt. % to the total mass of the product (e27). The number
average particle size of the product (e27) was 1.0 .mu.m.
[0390] Except for using the product (e27), Battery (A103) has an
identical configuration to that of Embodiment E102. This battery
was termed Embodiment E103.
Embodiment E104
[0391] The surface of SiO particle (t) was supported with nickel,
as the electronic conductive additive (B), by electroless plating
technique with the use of Ni-801 (Kojundo Chemical Laboratory) as a
plating solution, so that a product (e28) was prepared. The
proportion of the electronic conductive additive (B) was determined
to be 10.0 wt. % to the total mass of the product (e28). The number
average particle size of the product (e28) was 1.0 .mu.m.
[0392] Except for using the product (e28), Battery (A104) has an
identical configuration to that of Embodiment E103. This battery
was termed Embodiment E104.
Embodiment E105
[0393] The surface of SiO particle (t) was supported with nickel,
as the electronic conductive additive (B), by electroless plating
technique with the use of Ni-801 (Kojundo Chemical Laboratory) as a
plating solution, so that a product (e29) was prepared. The
proportion of the electronic conductive additive (B) was determined
to be 20.0 wt. % to the total mass of the product (e29). The number
average particle size of the product (e29) was 1.0 .mu.m.
[0394] Except for using the product (e29), Battery (A105) has an
identical configuration to that of Embodiment E103. This battery
was termed Embodiment E105.
Embodiment E106
[0395] The surface of SiO particle (t) was supported with nickel,
as the electronic conductive additive (B), by electroless plating
technique with the use of Ni-801 (Kojundo Chemical Laboratory) as a
plating solution, so that a product (e30) was prepared. The
proportion of the electronic conductive additive (B) was determined
to be 30.0 wt. % to the total mass of the product (e30). The number
average particle size of the product (e30) was 1.0 .mu.m.
[0396] Except for using the product (e30), Battery (A106) has an
identical configuration to that of Embodiment E103. This battery
was termed Embodiment E106.
Embodiment E107
[0397] The surface of SiO particle (t) was supported with nickel,
as the electronic conductive additive (B), by electroless plating
technique with the use of Ni-801 (Kojundo Chemical Laboratory) as a
plating solution, so that a product (e31) was prepared. The
proportion of the electronic conductive additive (B) was determined
to be 38.0 wt. % to the total mass of the product (e31). The number
average particle size of the product (e31) was 1.1 .mu.m.
[0398] Except for using the product (e31), Battery (A107) has an
identical configuration to that of Embodiment E103. This battery
was termed Embodiment E107.
Embodiment E108
[0399] The surface of SiO particle (t) was supported with nickel,
as the electronic conductive additive (B), by electroless plating
technique with the use of Ni-801 (Kojundo Chemical Laboratory) as a
plating solution, so that a product (e32) was prepared. The
proportion of the electronic conductive additive (B) was determined
to be 40.0 wt. % to the total mass of the product (e32). The number
average particle size of the product (e32) was 1.21 .mu.m.
[0400] Except for using the product (e32), Battery (A108) has an
identical configuration to that of Embodiment E103. This battery
was termed Embodiment E108.
Comparative Example E9
[0401] The surface of SiO particle (t) was supported with nickel,
as the electronic conductive additive (B), by electroless plating
technique with the use of Ni-801 (Kojundo Chemical Laboratory) as a
plating solution, so that a product (e33) was prepared. The
proportion of the electronic conductive additive (B) was determined
to be 0.1 wt. % to the total mass of the product (e33). The number
average particle size of the product (e33) was 0.9 .mu.m.
[0402] Except for using the product (e33), Battery (317) has an
identical configuration to that of Embodiment E108. This battery
was termed Comparative Example E9.
Embodiment E161
[0403] The surface of SiO particle (t) was supported with nickel,
as the electronic conductive additive (B), by electroless plating
technique with the use of Ni-801 (Kojundo Chemical Laboratory) as a
plating solution, so that a product (e34) was prepared. The
proportion of the electronic conductive additive (B) was determined
to be 50.0 wt. % to the total mass of the product (e34). The number
average particle size of the product (e34) was 1.4 .mu.m.
[0404] Except for using the product (e34), Battery (B18) has an
identical configuration to that of Embodiment E108. This battery
was termed Embodiment E161.
Embodiment E109
[0405] By mechanochemical reaction between SiO particle (t) and
artificial graphite, as the carbon material (E), a composite was
prepared. The surface of such composite was supported with carbon,
as the electronic conductive additive (B), using the method (CVD)
of thermally decomposing toluene gas under argon atmosphere at
100000, so that a product (e35) was prepared. The proportions of
the electronic conductive additive (B) and the carbon material (E)
were determined to be 0.5 wt. % and 59.5 wt. %, respectively, to
the total mass of the product (e35). The number average particle
size of the product (e35) was 15.5 .mu.m.
[0406] 30 wt. % of the product (e35) and, as the carbon material
(D), 40 wt. % of meso carbon microbeads, 10 wt. % of natural
graphite and 20 wt. % of artificial graphite were mixed together to
prepare a negative active material. Except for the above, Battery
(A109) has an identical configuration to that of Embodiment E1.
This battery was termed Embodiment E109.
Embodiment E110
[0407] By mechanochemical reaction between SiO particle (t) and
artificial graphite, as the carbon material (E), a composite was
prepared. The surface of such composite was supported with carbon,
as the electronic conductive additive (B), using the method (CVD)
of thermally decomposing toluene gas under argon atmosphere at
1000.degree. C., so that a product (e36) was prepared. The
proportions of the electronic conductive additive (B) and the
carbon material (E) were determined to be 1.0 wt. % and 59.0 wt. %,
respectively, to the total mass of the product (e36). The number
average particle size of the product (e36) was 16.3 Jim.
[0408] Except for using this product (e36), Battery (A110) has an
identical configuration to that of Embodiment E109. This battery
was termed Embodiment E110.
Embodiment E111
[0409] By mechanochemical reaction between SiO particle (t) and
artificial graphite, as the carbon material (E), a composite was
prepared. The surface of such composite was supported with carbon;
as the electronic conductive additive (B), using the method (CVD)
of thermally decomposing toluene gas under argon atmosphere at
1000.degree. C., so that a product (e37) was prepared. The
proportions of the electronic conductive additive (B) and the
carbon material (E) were determined to be 10.0 wt. % and 50.0 wt.
%, respectively, to the total mass of the product (e37). The number
average particle size of the product (e37) was 18.3 .mu.m.
[0410] Except for using this product (e37), Battery (A111) has an
identical configuration to that of Embodiment E109. This battery
was termed Embodiment E11.
Embodiment E112
[0411] By mechanochemical reaction between SiO particle (t) and
artificial graphite, as the carbon material (E), a composite was
prepared. The surface of such composite was supported with carbon,
as the electronic conductive additive (B), using the method (CVD)
of thermally decomposing toluene gas under argon atmosphere at
1000.degree. C., so that a product (e38) was prepared. The
proportions of the electronic conductive additive (B) and the
carbon material (E) were determined to be 20.0 wt. % and 40.0 wt.
%, respectively, to the total mass of the product (e38). The number
average particle size of the product (e38) was 20.0 .mu.m.
[0412] Except for using this product (e38), Battery (A112) has an
identical configuration to that of Embodiment E109. This battery
was termed Embodiment E112.
Embodiment E113
[0413] By mechanochemical reaction between SiO particle (t) and
artificial graphite, as the carbon material (E), a composite was
prepared. The surface of such composite was supported with carbon,
as the electronic conductive additive (B), using the method (CVD)
of thermally decomposing toluene gas under argon atmosphere at
1000.degree. C., so that a product (e39) was prepared. The
proportions of the electronic conductive additive (B) and the
carbon material (E) were determined to be 30.0 wt. % and 30.0 wt.
%, respectively, to the total mass of the product (e39). The number
average particle size of the product (e39) was 20.3 .mu.m.
[0414] Except for using this product (e39), Battery (A113) has an
identical configuration to that of Embodiment E109. This battery
was termed Embodiment E113.
Embodiment E114
[0415] By mechanochemical reaction between SiO particle (t) and
artificial graphite, as the carbon material (E), a composite was
prepared. The surface of such composite was supported with carbon,
as the electronic conductive additive (B), using the method (CVD)
of thermally decomposing toluene gas under argon atmosphere at
1000.degree. C., so that a product (e40) was prepared. The
proportions of the electronic conductive additive (B) and the
carbon material (E) were determined to be 38.0 wt. % and 22.0 wt.
%, respectively, to the total mass of the product (e40). The number
average particle size of the product (e40) was 20.7 .mu.m.
[0416] Except for using this product (e40), Battery (A114) has an
identical configuration to that of Embodiment E109. This battery
was termed Embodiment E14.
Embodiment E115
[0417] By mechanochemical reaction between SiO particle (t) and
artificial graphite, as the carbon material (E), a composite was
prepared. The surface of such composite was supported with carbon,
as the electronic conductive additive (B), using the method (CVD)
of thermally decomposing toluene gas under argon atmosphere at
1000.degree. C., so that a product (e41) was prepared. The
proportions of the electronic conductive additive (B) and the
carbon material (E) were determined to be 40.0 wt. % and 20.0 wt.
%, respectively, to the total mass of the product (e41). The number
average particle size of the product (e41) was 21.7 .mu.m.
[0418] Except for using this product (e41), Battery (A115) has an
identical configuration to that of Embodiment E109. This battery
was termed Embodiment E115.
Comparative Example E10
[0419] By mechanochemical reaction between SiO particle (t) and
artificial graphite, as the carbon material (E), a composite was
prepared. The surface of such composite was supported with carbon,
as the electronic conductive additive (B), using the method (CVD)
of thermally decomposing toluene gas under argon atmosphere at
1000.degree. C., so that a product (e42) was prepared. The
proportions of the electronic conductive additive (B) and the
carbon material (E) were determined to be 0.1 wt. % and 59.9 wt. %,
respectively, to the total mass of the product (e42). The number
average particle size of the product (e42) was 14.5 .mu.m.
[0420] Except for using this product (e42), Battery (B19) has an
identical configuration to that of Embodiment E109. This battery
was termed Comparative Example E10.
Embodiment E162
[0421] By mechanochemical reaction between SiO particle (t) and
artificial graphite, as the carbon material (E), a composite was
prepared. The surface of such composite was supported with carbon,
as the electronic conductive additive (B), using the method (CVD)
of thermally decomposing toluene gas under argon atmosphere at
1000.degree. C., so that a product (e43) was prepared. The
proportions of the electronic conductive additive (B) and the
carbon material (E) were determined to be 50.0 wt. % and 10.0 wt.
%, respectively, to the total mass of the product (e43). The number
average particle size of the product (e43) was 22.55 .mu.m.
[0422] Except for using this product (e43), Battery (B320) has an
identical configuration to that of Embodiment E109. This battery
was termed Embodiment E162.
Embodiment E116
[0423] 10 wt. % of the product (e35) and, as the carbon material
(D), 40 wt. % of meso carbon microbeads, 30 wt. % of natural
graphite and 20 wt. % of artificial graphite were mixed together to
prepare a negative active material. Except for the above, Battery
(A116) has an identical configuration to that of Embodiment E1.
This battery was termed Embodiment E116.
Embodiment E117
[0424] Except for using the product (e86), Battery (A117) has an
identical configuration to that of Embodiment E116. This battery
was termed Embodiment E117.
Embodiment E118
[0425] Except for using the product (e37), Battery (A118) has an
identical configuration to that of Embodiment E116. This battery
was termed Embodiment E118.
Embodiment E119
[0426] Except for using the product (e38), Battery (A119) has an
identical configuration to that of Embodiment E116. This battery
was termed Embodiment E119.
Embodiment E120
[0427] Except for using the product (e39), Battery (A120) has an
identical configuration to that of Embodiment E116. This battery
was termed Embodiment E120.
Embodiment E121
[0428] Except for using the product (e40), Battery (A121) has an
identical configuration to that of Embodiment E116. This battery
was termed Embodiment E121.
Embodiment E122
[0429] Except for using the product (e41), Battery (A122) has an
identical configuration to that of Embodiment E116. This battery
was termed Embodiment E122.
Comparative Example E11
[0430] Except for using the product (e42), Battery (B21) has an
identical configuration to that of Embodiment E116. This battery
was termed Comparative Example E11.
Embodiment E163
[0431] Except for using the product (e43), Battery (B322) has an
identical configuration to that of Embodiment E116. This battery
was termed Embodiment E163
Embodiment E123
[0432] 5 wt. % of the product (e35) and, as the carbon material
(D), 40 wt. % of meso carbon microbeads, 35 wt. % of natural
graphite and 20 wt. % of artificial graphite were mixed together to
prepare a negative active material. Except for the above, Battery
(A123) has an identical configuration to that of Embodiment E1.
This battery was termed Embodiment E123.
Embodiment E124
[0433] Except for using the product (e36), Battery (A124) has an
identical configuration to that of Embodiment E123. This battery
was termed Embodiment E124.
Embodiment E125
[0434] Except for using the product (e37), Battery (A125) has an
identical configuration to that of Embodiment E123. This battery
was termed Embodiment E125.
Embodiment E126
[0435] Except for using the product (e38), Battery (A126) has an
identical configuration to that of Embodiment E123. This battery
was termed Embodiment E126.
Embodiment E127
[0436] Except for using the product (e39), Battery (A127) has an
identical configuration to that of Embodiment E123. This battery
was termed Embodiment E127.
Embodiment E128
[0437] Except for using the product (e40), Battery (A128) has an
identical configuration to that of Embodiment E123. This battery
was termed Embodiment E128.
Embodiment E129
[0438] Except for using the product (e41), Battery (A129) has an
identical configuration to that of Embodiment E123. This battery
was termed Embodiment E129.
Comparative Example E12
[0439] Except for using the product (e42), Battery (B23) has an
identical configuration to that of Embodiment E123. This battery
was termed Comparative Example E12.
Embodiment E164
[0440] Except for using the product (e43), Battery (B24) has an
identical configuration to that of Embodiment E123. This battery
was termed Embodiment E164
Embodiment E130
[0441] 1 wt. % of the product (e35) and, as the carbon material
(D), 40 wt. % of meso carbon microbeads, 39 wt. % of natural
graphite and 20 wt. % of artificial graphite were mixed together to
prepare a negative active material. Except for the above, Battery
(A130) has an identical configuration to that of Embodiment E1.
This battery was termed Embodiment E130.
Embodiment E131
[0442] Except for using the product (e36), Battery (A131) has an
identical configuration to that of Embodiment E130. This battery
was termed Embodiment E131.
Embodiment E132
[0443] Except for using the product (e37), Battery (A132) has an
identical configuration to that of Embodiment E130. This battery
was termed Embodiment E132.
Embodiment E138
[0444] Except for using the product (e38), Battery (A133) has an
identical configuration to that of Embodiment E130. This battery
was termed Embodiment E133.
Embodiment E134
[0445] Except for using the product (e39), Battery (A134) has an
identical configuration to that of Embodiment E130. This battery
was termed Embodiment E134.
Embodiment E135
[0446] Except for using the product (e40), Battery (A135) has an
identical configuration to that of Embodiment E130. This battery
was termed Embodiment E135.
Embodiment E136
[0447] Except for using the product (e41), Battery (A136) has an
identical configuration to that of Embodiment E130. This battery
was termed Embodiment E136.
Comparative Example E13
[0448] Except for using the product (e42), Battery (B25) has an
identical configuration to that of Embodiment E130. This battery
was termed Comparative Example E13.
Embodiment E165
[0449] Except for using the product (e43), Battery (B26) has an
identical configuration to that of Embodiment E130. This battery
was termed Embodiment E165
Embodiment E137
[0450] 35 wt. % of the product (e35) and, as the carbon material
(D), 40 wt. % of meso carbon microbeads, 5 wt. % of natural
graphite and 20 wt. % of artificial graphite were mixed together to
prepare a negative active material. Except for the above, Battery
(A137) has an identical configuration to that of Embodiment E1.
This battery was termed Embodiment E137.
Embodiment E138
[0451] 20 wt. % of the product (e35) and, as the carbon material
(D), 40 wt. % of meso carbon microbeads, 20 wt. % of natural
graphite and 20 wt. % of artificial graphite were mixed together to
prepare a negative active material. Except for the above, Battery
(A138) has an identical configuration to that of Embodiment E1.
This battery was termed Embodiment E138.
Embodiment E139
[0452] 0.5 wt. % of the product (e35) and, as the carbon material
(D), 40 wt. % of meso carbon microbeads, 35.5 wt. % of natural
graphite and 20 wt. % of artificial graphite were mixed together to
prepare a negative active material. Except for the above, Battery
(A139) has an identical configuration to that of Embodiment E1.
This battery was termed Embodiment E139.
Embodiment E140
[0453] 35 wt. % of the product (e38) and, as the carbon material
(D), 40 wt. % of meso carbon microbeads, 5 wt. % of natural
graphite and 20 wt. % of artificial graphite were mixed together to
prepare a negative active material. Except for the above, Battery
(A140) has an identical configuration to that of Embodiment E1.
This battery was termed Embodiment E140.
Embodiment E141
[0454] 20 wt. % of the product (e38) and, as the carbon material
(D), 40 wt. % of meso carbon microbeads, 20 wt. % of natural
graphite and 20 wt. % of artificial graphite were mixed together to
prepare a negative active material. Except for the above, Battery
(A141) has an identical configuration to that of Embodiment E1.
This battery was termed Embodiment E141.
Embodiment E142
[0455] 0.5 wt. % of the product (e38) and, as the carbon material
(D), 40 wt. % of meso carbon microbeads, 35.5 wt. % of natural
graphite and 20 wt. % of artificial graphite were mixed together to
prepare a negative active material. Except for the above, Battery
(A142) has an identical configuration to that of Embodiment E1.
This battery was termed Embodiment E142.
Embodiment E143
[0456] 35 wt. % of the product (e41) and, as the carbon material
(D), 40 wt. % of meso carbon microbeads, 5 wt. % of natural
graphite and 20 wt. % of artificial graphite were mixed together to
prepare a negative active material. Except for the above, Battery
(A143) has an identical configuration to that of Embodiment E1.
This battery was termed Embodiment E143.
Embodiment E144
[0457] 20 wt. % of the product (e41) and, as the carbon material
(D), 40 wt. % of meso carbon microbeads, 20 wt. % of natural
graphite and 20 wt. % of artificial graphite were mixed together to
prepare a negative active material. Except for the above, Battery
(A144) has an identical configuration to that of Embodiment E1.
This battery was termed Embodiment E144.
Embodiment E145
[0458] 0.5 wt. % of the product (e41) and, as the carbon material
(D), 40 wt. % of meso carbon microbeads, 35.5 wt. % of natural
graphite and 20 wt. % of artificial graphite were mixed together to
prepare a negative active material. Except for the above, Battery
(A145) has an identical configuration to that of Embodiment E1.
This battery was termed Embodiment E145.
Embodiment E146
[0459] By mechanochemical reaction between SiO particle (t) and
artificial graphite, as the carbon material (E), a composite was
prepared. The surface of such composite was supported with copper,
as the electronic conductive additive (B), by electroless plating
technique with the use of C200LT solution (Kojundo Chemical
Laboratory) as a plating solution, so that a product (e44) was
prepared. The proportions of the electronic conductive additive (B)
and the carbon material (E) were determined to be 0.5 wt. % and
59.5 wt. %, respectively, to the total mass of the product (e44).
The number average particle size of the product (e44) was 13.2
.mu.m.
[0460] 10 wt. % of the product (e44) and, as the carbon material
(D), 40 wt. % of meso carbon microbeads, 30 wt. % of natural
graphite and 20 wt. % of artificial graphite were mixed together to
prepare a negative active material. Except for the above, Battery
(A146) has an identical configuration to that of Embodiment E1.
This battery was termed Embodiment E146.
Embodiment E147
[0461] By mechanochemical reaction between SiO particle (t) and
artificial graphite, as the carbon material (E), a composite was
prepared. The surface of such composite was supported with copper,
as the electronic conductive additive (B), by electroless plating
technique with the use of C200LT solution (Kojundo Chemical
Laboratory) as a plating solution, so that a product (e45) was
prepared. The proportions of the electronic conductive additive (B)
and the carbon material (E) were determined to be 1.0 wt. % and
59.0 wt. %, respectively, to the total mass of the product (e45).
The number average particle size of the product (e45) was 14.2
.mu.m.
[0462] Except for using this product (e45), Battery (A147) has an
identical configuration to that of Embodiment E146. This battery
was termed Embodiment E147.
Embodiment E148
[0463] By mechanochemical reaction between SiO particle (t) and
artificial graphite, as the carbon material (E), a composite was
prepared. The surface of such composite was supported with copper,
as the electronic conductive additive (B), by electroless plating
technique with the use of C200LT solution (Kojundo Chemical
Laboratory) as a plating solution, so that a product (e46) was
prepared. The proportions of the electronic conductive additive (B)
and the carbon material (E) were determined to be 10.0 wt. % and
50.0 wt. %, respectively, to the total mass of the product (e46).
The number average particle size of the product (e46) was 15.4
.mu.m.
[0464] Except for using this product (e46), Battery (A148) has an
identical configuration to that of Embodiment E146. This battery
was termed Embodiment E148.
Embodiment E149
[0465] By mechanochemical reaction between SiO particle (t) and
artificial graphite, as the carbon material (E), a composite was
prepared. The surface of such composite was supported with copper,
as the electronic conductive additive (B), by electroless plating
technique with the use of C200LT solution (Kojundo Chemical
Laboratory) as a plating solution, so that a product (e47) was
prepared. The proportions of the electronic conductive additive (B)
and the carbon material (E) were determined to be 20.0 wt. % and
40.0 wt. %, respectively, to the total mass of the product (e47).
The number average particle size of the product (e47) was 16.71
.mu.m.
[0466] Except for using this product (e47), Battery (A149) has an
identical configuration to that of Embodiment E146. This battery
was termed Embodiment E149.
Embodiment E150
[0467] By mechanochemical reaction between SiO particle (t) and
artificial graphite, as the carbon material (E), a composite was
prepared. The surface of such composite was supported with copper,
as the electronic conductive additive (B), by electroless plating
technique with the use of C200LT solution (Kojundo Chemical.
Laboratory) as a plating solution, so that a product (e48) was
prepared. The proportions of the electronic conductive additive (B)
and the carbon material (E) were determined to be 30.0 wt. % and
30.0 wt. %, respectively, to the total mass of the product (e48).
The number average particle size of the product (e48) was 18.2
.mu.m.
[0468] Except for using this product (e48), Battery (A150) has an
identical configuration to that of Embodiment E146. This battery
was termed Embodiment E150.
Embodiment E151
[0469] By mechanochemical reaction between SiO particle (t) and
artificial graphite, as the carbon material (E), a composite was
prepared. The surface of such composite was supported with copper,
as the electronic conductive additive (B), by electroless plating
technique with the use of C200LT solution (Kojundo Chemical
Laboratory) as a plating solution, so that a product (e49) was
prepared. The proportions of the electronic conductive additive (B)
and the carbon material (E) were determined to be 38.0 wt. % and
22.0 wt. %, respectively, to the total mass of the product (e49).
The number average particle size of the product (e49) was 19.9
.mu.m.
[0470] Except for using this product (e49), Battery (A151) has an
identical configuration to that of Embodiment E146. This battery
was termed Embodiment E151.
Embodiment E152
[0471] By mechanochemical reaction between SiO particle (t) and
artificial graphite, as the carbon material (E), a composite was
prepared. The surface of such composite was supported with copper,
as the electronic conductive additive (B), by electroless plating
technique with the use of C200LT solution (Kojundo Chemical
Laboratory) as a plating solution, so that a product (e50) was
prepared. The proportions of the electronic conductive additive (B)
and the carbon material (E) were determined to be 40.0 wt. % and
20.0 wt. %, respectively, to the total mass of the product (e50).
The number average particle size of the product (e50) was 20.2
.mu.m.
[0472] Except for using this product (e50), Battery (A152) has an
identical configuration to that of Embodiment E146. This battery
was termed Embodiment E152.
Comparative Example E14
[0473] By mechanochemical reaction between SiO particle (t) and
artificial graphite, as the carbon material (E), a composite was
prepared. The surface of such composite was supported with copper,
as the electronic conductive additive (B), by electroless plating
technique with the use of C200LT solution (Kojundo Chemical
Laboratory) as a plating solution, so that a product (e51) was
prepared. The proportions of the electronic conductive additive (B)
and the carbon material (E) were determined to be 0.1 wt. % and
59.9 wt. %, respectively, to the total mass of the product (e51).
The number average particle size of the product (e51) was 13.0
.mu.m.
[0474] Except for using this product (e51), Battery (B27) has an
identical configuration to that of Embodiment E146. This battery
was termed Comparative Example E14.
Embodiment E166
[0475] By mechanochemical reaction between SiO particle (t) and
artificial graphite, as the carbon material (E), a composite was
prepared. The surface of such composite was supported with copper,
as the electronic conductive additive (B), by electroless plating
technique with the use of C200LT solution (Kojundo Chemical
Laboratory) as a plating solution, so that a product (e52) was
prepared. The proportions of the electronic conductive additive (B)
and the carbon material (E) were determined to be 50.0 wt. % and
10.0 wt. %, respectively, to the total mass of the product (e52).
The number average particle size of the product (e52) was 21.1
m.
[0476] Except for using this product (e52), Battery (B28) has an
identical configuration to that of Embodiment E146. This battery
was termed Embodiment E166.
Comparative Example E15
[0477] Except for using artificial graphite as the negative active
material, Battery (B29) has an identical configuration to that of
Embodiment E1. This battery was termed Comparative Example E15.
Comparative Example E16
[0478] Except for using the product (e1) as the negative active
material, Battery (B30) has an identical configuration to that of
Embodiment E1. This battery was termed Comparative Example E16.
<Measurement of Particle Size Distribution>
[0479] The particle size distribution described in this description
was measured according to the following manner. 0.1 g of sample was
stirred in water and this preparation was sent to a measuring
stand. With the use of a semiconductor laser (wave length of 680
nm, and power of 3 mW) as a light source, the preparation was
measured by means of laser diffraction and laser scattering methods
(SALD2000J, SHIMADZU).
<Charge/Discharge Test>
[0480] Each battery described above was charged at a current of 1
CmA (700 mA) at a temperature of 25.degree. C. until the voltage
reached 4.2 V, subsequently charged at a constant voltage of 4.2 V
for 2 hours, and then discharged at a current of 1 CmA until the
voltage dropped to 2.0 V. These steps were taken as one cycle, and
the initial capacity and the capacity retention ratio after 500
cycles were examined.
[0481] The initial capacity described in this description means the
discharge capacity at the 1.sup.st cycle, and the capacity
retention ratio means the ratio of the discharge capacity at the
500.sup.th cycle to the one at the 1.sup.st cycle (expressed in
percentage).
TABLE-US-00031 TABLE E1 Active material (C) Electronic Amount of
Amount of Result conductive (B) support (D) mixture Initial
Capacity Material additive wt. % wt. % capacity retention (A) (B)
(B)/(C) (D)/((C) + (D)) mAh ratio % CE E1 Si C 0.1 0.5 702 12 EM E1
Si C 0.5 0.5 811 52 EM E2 Si C 5.0 0.5 822 61 EM E3 Si C 10.0 0.5
823 63 EM E4 Si C 20.0 0.5 819 67 EM E5 Si C 30.0 0.5 805 64 EM E6
Si C 38.0 0.5 798 63 EM E7 Si C 40.0 0.5 795 55 EM E153 Si C 50.0
0.5 712 40
[0482] In Tables E1 to E27, EM in the first column refers to
Embodiment and CE refers to Comparative Example; for example, EM E1
refers to Embodiment E1 and CE E1 refers to Comparative Example
E1.
TABLE-US-00032 TABLE E2 Active material (C) Electronic Amount of
Amount of Result conductive (B) support (D) mixture Initial
Capacity Material additive wt. % wt. % capacity retention (A) (B)
(B)/(C) (D)/((C) + (D)) mAh ratio % CE E2 Si C 0.1 20.0 687 16 EM
E8 Si C 0.5 20.0 783 54 EM E9 Si C 5.0 20.0 794 64 EM E10 Si C 10.0
20.0 798 67 EM E11 Si C 20.0 20.0 784 70 EM E12 Si C 30.0 20.0 772
69 EM E13 Si C 38.0 20.0 764 67 EM E14 Si C 40.0 20.0 741 57 EM
E154 Si C 50.0 20.0 673 42
TABLE-US-00033 TABLE E3 Active material (C) Amount Electronic of
(B) Amount of Result Ma- conductive support (D) mixture Initial
Capacity terial additive wt. % wt. % (D)/ capacity retention (A)
(B) (B)/(C) ((C) + (D)) mAh ratio % EM E15 Si C 0.5 0.1 753 50 EM
E1 Si C 0.5 0.5 811 52 EM E16 Si C 0.5 1.0 806 65 EM E17 Si C 0.5
5.0 798 70 EM E18 Si C 0.5 10.0 794 69 EM E19 Si C 0.5 15.0 789 62
EM E8 Si C 0.5 20.0 783 54 EM E20 Si C 0.5 25.0 730 51
TABLE-US-00034 TABLE E4 Active material (C) Amount Electronic of
(B) Amount of Result Ma- conductive support (D) mixture Initial
Capacity terial additive wt. % wt. % (D)/ capacity retention (A)
(B) (B)/(C) ((C) + (D)) mAh ratio % EM E21 Si C 20.0 0.1 739 50 EM
E4 Si C 20.0 0.5 819 55 EM E22 Si C 20.0 1.0 813 69 EM E23 Si C
20.0 5.0 809 72 EM E24 Si C 20.0 10.0 802 75 EM E25 Si C 20.0 15.0
794 74 EM E11 Si C 20.0 20.0 786 72 EM E26 Si C 20.0 25.0 730
51
TABLE-US-00035 TABLE E5 Active material (C) Amount Electronic of
(B) Amount of Result Ma- conductive support (D) mixture Initial
Capacity terial additive wt. % wt. % (D)/ capacity retention (A)
(B) (B)/(C) ((C) + (D)) mAh ratio % EM E27 Si C 40.0 0.1 724 51 EM
E7 Si C 40.0 0.5 795 55 EM E28 Si C 40.0 1.0 790 69 EM E29 Si C
40.0 5.0 782 73 EM E30 Si C 40.0 10.0 775 75 EM E31 Si C 40.0 15.0
759 68 EM E14 Si C 40.0 20.0 741 57 EM E32 Si C 40.0 25.0 714
50
TABLE-US-00036 TABLE E6 Active material (F) Electronic Amount of
Amount of Amount of Result conductive (B) support (E) mixture (D)
mixture Initial Capacity Material additive wt. % wt. % wt. %
capacity retention (A) (B) (B)/(F) (E)/(F) (D)/((F) + (D)) mAh
ratio % CE E3 Si C 0.1 59.9 0.5 692 32 EM E33 Si C 0.5 59.5 0.5 798
63 EM E34 Si C 5.0 59.0 0.5 802 72 EM E35 Si C 10.0 50.0 0.5 805 75
EM E36 Si C 20.0 40.0 0.5 799 78 EM E37 Si C 30.0 30.0 0.5 785 73
EM E38 Si C 38.0 22.0 0.5 778 70 EM E39 Si C 40.0 20.0 0.5 776 64
EM E155 Si C 50.0 10.0 0.5 684 42
TABLE-US-00037 TABLE E7 Active material (F) Electronic Amount of
Amount of Amount of Result conductive (B) support (E) mixture (D)
mixture Initial Capacity Material additive wt. % wt. % wt. %
capacity retention (A) (B) (B)/(F) (E)/(F) (D)/((F) + (D)) mAh
ratio % CE E4 Si C 0.1 59.9 20.0 669 35 EM E40 Si C 0.5 59.5 20.0
764 64 EM E41 Si C 5.0 59.0 20.0 779 73 EM E42 Si C 10.0 50.0 20.0
779 75 EM E43 Si C 20.0 40.0 20.0 768 79 EM E44 Si C 30.0 30.0 20.0
759 74 EM E45 Si C 38.0 22.0 20.0 742 73 EM E46 Si C 40.0 20.0 20.0
725 65 EM E156 Si C 50.0 10.0 20.0 659 43
TABLE-US-00038 TABLE E8 Active material (F) Electronic Amount of
Amount of Amount of Result conductive (B) support (E) mixture (D)
mixture Initial Capacity Material additive wt. % wt. % wt. %
capacity retention (A) (B) (B)/(F) (E)/(F) (D)/((F) + (D)) mAh
ratio % EM E47 Si C 0.5 59.5 0.1 731 60 EM E27 Si C 0.5 59.5 0.5
798 63 EM E48 Si C 0.5 59.5 1.0 792 75 EM E49 Si C 0.5 59.5 5.0 785
78 EM E50 Si C 0.5 59.5 10.0 781 75 EM E51 Si C 0.5 59.5 15.0 774
69 EM E34 Si C 0.5 59.5 20.0 764 64 EM E52 Si C 0.5 59.5 25.0 701
58
TABLE-US-00039 TABLE E9 Active material (F) Electronic Amount of
Amount of Amount of Result conductive (B) support (E) mixture (D)
mixture Initial Capacity Material additive wt. % wt. % wt. %
capacity retention (A) (B) (B)/(F) (E)/(F) (D)/((F) + (D)) mAh
ratio % EM E53 Si C 20.0 40.0 0.1 717 61 EM E30 Si C 20.0 40.0 0.5
799 78 EM E54 Si C 20.0 40.0 1.0 793 79 EM E55 Si C 20.0 40.0 5.0
785 80 EM E56 Si C 20.0 40.0 10.0 776 79 EM E57 Si C 20.0 40.0 15.0
770 79 EM E37 Si C 20.0 40.0 20.0 768 79 EM E58 Si C 20.0 40.0 25.0
715 63
TABLE-US-00040 TABLE E10 Active material (F) Electronic Amount of
Amount of Amount of Result conductive (B) support (E) mixture (D)
mixture Initial Capacity Material additive wt. % wt. % wt. %
capacity retention (A) (B) (B)/(F) (E)/(F) (D)/((F) + (D)) mAh
ratio % EM E59 Si C 40.0 20.0 0.1 689 58 EM E33 Si C 40.0 20.0 0.5
776 64 EM E60 Si C 40.0 20.0 1.0 773 69 EM E61 Si C 40.0 20.0 5.0
763 73 EM E62 Si C 40.0 20.0 10.0 756 72 EM E63 Si C 40.0 20.0 15.0
741 70 EM E40 Si C 40.0 20.0 20.0 725 65 EM E64 Si C 40.0 20.0 25.0
684 52
TABLE-US-00041 TABLE E11 Active material (C) Electronic Amount of
Amount of Result conductive (B) support (D) mixture Initial
Capacity Material additive wt. % wt. % capacity retention (A) (B)
(B)/(F) (D)/((C) + (D)) mAh ratio % CE E5 SiO C 0.1 70.0 580 42 EM
E65 SiO C 0.5 70.0 730 54 EM E66 SiO C 1.0 70.0 745 72 EM E67 SiO C
10.0 70.0 749 74 EM E68 SiO C 20.0 70.0 754 68 EM E69 SiO C 30.0
70.0 760 66 EM E70 SiO C 38.0 70.0 768 65 EM E71 SiO C 40.0 70.0
710 56 EM E157 SiO C 50.0 70.0 630 34
TABLE-US-00042 TABLE E12 Active material (C) Electronic Amount of
Amount of Result conductive (B) support (D) mixture Initial
Capacity Material additive wt. % wt. % capacity retention (A) (B)
(B)/(C) (D)/((C) + (D)) mAh ratio % CE E6 SiO C 0.1 90.0 590 44 EM
E72 SiO C 0.5 90.0 760 56 EM E73 SiO C 1.0 90.0 752 72 EM E74 SiO C
10.0 90.0 754 86 EM E75 SiO C 20.0 90.0 749 75 EM E76 SiO C 30.0
90.0 739 78 EM E77 SiO C 38.0 90.0 732 77 EM E78 SiO C 40.0 90.0
700 76 EM E158 SiO C 50.0 90.0 642 41
TABLE-US-00043 TABLE E13 Active material (C) Electronic Amount of
Amount of Result conductive (B) support (D) mixture Initial
Capacity Material additive wt. % wt. % capacity retention (A) (B)
(B)/(C) (D)/((C) + (D)) mAh ratio % CE E7 SiO C 0.1 95.0 595 45 EM
E79 SiO C 0.5 95.0 730 58 EM E80 SiO C 1.0 95.0 763 75 EM E81 SiO C
10.0 95.0 769 83 EM E82 SiO C 20.0 95.0 750 86 EM E83 SiO C 30.0
95.0 745 84 EM E84 SiO C 38.0 95.0 740 81 EM E85 SiO C 40.0 95.0
708 77 EM E159 SiO C 50.0 95.0 645 45
TABLE-US-00044 TABLE E14 Active material (C) Electronic Amount of
Amount of Result conductive (B) support (D) mixture Initial
Capacity Material additive wt. % wt. % capacity retention (A) (B)
(B)/(C) (D)/((C) + (D)) mAh ratio % CE E8 SiO C 0.1 99.0 598 48 EM
E86 SiO C 0.5 99.0 721 62 EM E87 SiO C 1.0 99.0 763 76 EM E88 SiO C
10.0 99.0 755 77 EM E89 SiO C 20.0 99.0 730 80 EM E90 SiO C 30.0
99.0 729 78 EM E91 SiO C 38.0 99.0 723 75 EM E92 SiO C 40.0 99.0
703 73 EM E160 SiO C 50.0 99.0 649 49
TABLE-US-00045 TABLE E15 Active material (C) Electronic Amount of
Amount of Result conductive (B) support (D) mixture Initial
Capacity Material additive wt. % wt. % capacity retention (A) (B)
(B)/(C) (D)/((C) + (D)) mAh ratio % EM E93 SiO C 0.5 67.0 702 51 EM
E53 SiO C 0.5 70.0 730 54 EM E94 SiO C 0.5 80.0 745 55 EM E60 SiO C
0.5 90.0 760 56 EM E67 SiO C 0.5 95.0 730 58 EM E74 SiO C 0.5 99.0
721 62 EM E95 SiO C 0.5 99.5 704 63
TABLE-US-00046 TABLE E16 Active material (C) Electronic Amount of
Amount of Result conductive (B) support (D) mixture Initial
Capacity Material additive wt. % wt. % capacity retention (A) (B)
(B)/(C) (D)/((C) + (D)) mAh ratio % EM E96 SiO C 20 67.0 730 53 EM
E56 SiO C 20.0 70.0 754 68 EM E97 SiO C 20.0 80.0 755 76 EM E63 SiO
C 20.0 90.0 749 75 EM E70 SiO C 20.0 95.0 750 86 EM E77 SiO C 20.0
99.0 730 80 EM E98 SiO C 20.0 99.5 752 85
TABLE-US-00047 TABLE E17 Active material (C) Electronic Amount of
Result conductive Amount of (B) (D) mixture Initial Capacity
Material additive support wt. % wt. % capacity retention (A) (B)
(B)/(C) (D)/((C) + (D)) mAh ratio % EM E99 SiO C 40.0 67.0 702 51
EM E59 SiO C 40.0 70.0 710 56 EM E100 SiO C 40.0 80.0 705 68 EM E66
SiO C 40.0 90.0 700 76 EM E73 SiO C 40.0 95.0 708 77 EM E80 SiO C
40.0 99.0 703 73 EM E101 SiO C 40.0 99.5 700 72
TABLE-US-00048 TABLE E18 Active material (C) Electronic Amount of
Amount of Result conductive (B) support (D) mixture Initial
Capacity Material additive wt. % wt. % capacity retention (A) (B)
(B)/(C) (D)/((C) + (D)) mAh ratio % CE E9 SiO Ni 0.1 95.0 545 38 EM
E84 SiO Ni 0.5 95.0 702 52 EM E85 SiO Ni 1.0 95.0 733 65 EM E86 SiO
Ni 10.0 95.0 739 73 EM E87 SiO Ni 20.0 95.0 720 75 EM E88 SiO Ni
30.0 95.0 715 72 EM E89 SiO Ni 38.0 95.0 710 69 EM E90 SiO Ni 40.0
95.0 705 65 EM E161 SiO Ni 50.0 95.0 602 32
TABLE-US-00049 TABLE E19 Active material (F) Electronic Amount of
Amount of Amount of Result conductive (B) support (E) mixture (D)
mixture Initial Capacity Material additive wt. % wt. % wt. %
capacity retention (A) (B) (B)/(F) (E)/(F) (D)/((F) + (D)) mAh
ratio % CE E10 SiO C 0.1 59.9 70.0 565 38 EM E109 SiO C 0.5 59.5
70.0 726 63 EM E110 SiO C 1.0 59.0 70.0 739 81 EM E111 SiO C 10.0
50.0 70.0 740 85 EM E112 SiO C 20.0 40.0 70.0 741 74 EM E113 SiO C
30.0 30.0 70.0 745 72 EM E114 SiO C 38.0 22.0 70.0 746 71 EM E115
SiO C 40.0 20.0 70.0 702 65 EM E162 SiO C 50.0 10.0 70.0 615 44
TABLE-US-00050 TABLE E20 Active material (F) Electronic Amount of
Amount of Amount of Result conductive (B) support (E) mixture (D)
mixture Initial Capacity Material additive wt. % wt. % wt. %
capacity retention (A) (B) (B)/(F) (E)/(F) (D)/((F) + (D)) mAh
ratio % CE E11 SiO C 0.1 59.9 90.0 680 42 EM E116 SiO C 0.5 59.5
90.0 745 61 EM E117 SiO C 1.0 59.0 90.0 743 74 EM E118 SiO C 10.0
50.0 90.0 740 78 EM E119 SiO C 20.0 40.0 90.0 736 82 EM E120 SiO C
30.0 30.0 90.0 728 80 EM E121 SiO C 38.0 22.0 90.0 714 79 EM E122
SiO C 40.0 20.0 90.0 680 78 EM E163 SiO C 50.0 10.0 90.0 673 64
TABLE-US-00051 TABLE E21 Active material (F) Electronic Amount of
Amount of Amount of Result conductive (B) support (E) mixture (D)
mixture Initial Capacity Material additive wt. % wt. % wt. %
capacity retention (A) (B) (B)/(F) (E)/(F) (D)/((F) + (D)) mAh
ratio % CE E12 SiO C 0.1 59.9 95.0 675 40 EM E123 SiO C 0.5 59.5
95.0 721 63 EM E124 SiO C 1.0 59.0 95.0 725 71 EM E125 SiO C 10.0
50.0 95.0 729 77 EM E126 SiO C 20.0 40.0 95.0 732 82 EM E127 SiO C
30.0 30.0 95.0 726 78 EM E128 SiO C 38.0 22.0 95.0 723 74 EM E129
SiO C 40.0 20.0 95.0 719 72 EM E164 SiO C 50.0 10.0 95.0 670 63
TABLE-US-00052 TABLE E22 Active material (F) Electronic Amount of
Amount of Amount of Result conductive (B) support (E) mixture (D)
mixture Initial Capacity Material additive wt. % wt. % wt. %
capacity retention (A) (B) (B)/(F) (E)/(F) (D)/((F) + (D)) mAh
ratio % CE E13 SiO C 0.1 59.9 99.0 642 39 EM E130 SiO C 0.5 59.5
99.0 692 65 EM E131 SiO C 1.0 59.0 99.0 703 73 EM E132 SiO C 10.0
50.0 99.0 711 78 EM E133 SiO C 20.0 40.0 99.0 719 83 EM E134 SiO C
30.0 30.0 99.0 704 79 EM E135 SiO C 38.0 22.0 99.0 702 75 EM E136
SiO C 40.0 20.0 99.0 698 72 EM E165 SiO C 50.0 10.0 99.0 630 68
TABLE-US-00053 TABLE E23 Active material (F) Electronic Amount of
Amount of Amount of Result conductive (B) support (E) mixture (D)
mixture Initial Capacity Material additive wt. % wt. % wt. %
capacity retention (A) (B) (B)/(F) (E)/(F) (D)/((F) + (D)) mAh
ratio % EM E137 SiO C 0.5 59.5 67.0 681 52 EM E91 SiO C 0.5 59.5
70.0 726 63 EM E138 SiO C 0.5 59.5 80.0 734 62 EM E98 SiO C 0.5
59.5 90.0 745 61 EM E105 SiO C 0.5 59.5 95.0 721 63 EM E112 SiO C
0.5 59.5 99.0 692 65 EM E139 SiO C 0.5 59.5 99.5 682 51
TABLE-US-00054 TABLE E24 Active material (F) Electronic Amount of
Amount of Amount of Result conductive (B) support (E) mixture (D)
mixture Initial Capacity Material additive wt. % wt. % wt. %
capacity retention (A) (B) (B)/(F) (E)/(F) (D)/((F) + (D)) mAh
ratio % EM E140 SiO C 20.0 40.0 67.0 740 58 EM E94 SiO C 20.0 40.0
70.0 741 74 EM E141 SiO C 20.0 40.0 80.0 747 79 EM E101 SiO C 20.0
40.0 90.0 736 82 EM E108 SiO C 20.0 40.0 95.0 732 82 EM E115 SiO C
20.0 40.0 99.0 719 83 EM E142 SiO C 20.0 40.0 99.5 672 79
TABLE-US-00055 TABLE E25 Active material (F) Electronic Amount of
Amount of Amount of Result conductive (B) support (E) mixture (D)
mixture Initial Capacity Material additive wt. % wt. % wt. %
capacity retention (A) (B) (B)/(F) (E)/(F) (D)/((F) + (D)) mAh
ratio % EM E143 SiO C 40.0 20.0 67.0 692 51 EM E97 SiO C 40.0 20.0
70.0 702 65 EM E144 SiO C 40.0 20.0 80.0 710 74 EM E104 SiO C 40.0
20.0 90.0 680 78 EM E111 SiO C 40.0 20.0 95.0 719 72 EM E118 SiO C
40.0 20.0 99.0 698 72 EM E145 SiO C 40.0 20.0 99.5 681 56
TABLE-US-00056 TABLE E26 Active material (F) Electronic Amount of
Amount of Amount of Result conductive (B) support (E) mixture (D)
mixture Initial Capacity Material additive wt. % wt. % wt. %
capacity retention (A) (B) (B)/(F) (E)/(F) (D)/((F) + (D)) mAh
ratio % CE E14 SiO Cu 0.1 59.9 90.0 660 41 EM E146 SiO Cu 0.5 59.5
90.0 725 59 EM E147 SiO Cu 1.0 59.0 90.0 723 69 EM E148 SiO Cu 10.0
50.0 90.0 720 74 EM E149 SiO Cu 20.0 40.0 90.0 716 75 EM E150 SiO
Cu 30.0 30.0 90.0 709 74 EM E151 SiO Cu 38.0 22.0 90.0 694 72 EM
E152 SiO Cu 40.0 20.0 90.0 680 71 EM E166 SiO Cu 50.0 10.0 90.0 632
57
TABLE-US-00057 TABLE E27 Active material (C) Electronic Amount of
Amount of Result conductive (B) support (D) mixture Initial
Capacity Material additive wt. % wt. % capacity retention (A) (B)
(B)/(C) (D)/((C) + (D)) mAh ratio % CE E15 C -- -- -- 615 80 CE E16
Si C 0.5 -- 820 9
INDUSTRIAL APPLICABILITY
[0483] The present invention provides a secondary battery which has
a large discharge capacity as well as satisfactory cycle
performance.
* * * * *