U.S. patent application number 12/713750 was filed with the patent office on 2010-08-26 for non-aqueous liquid electrolyte and non-aqueous liquid electrolyte secondary battery using the same.
This patent application is currently assigned to Mitsubishi Chemical Corporation. Invention is credited to Noriko SHIMA.
Application Number | 20100216036 12/713750 |
Document ID | / |
Family ID | 37570260 |
Filed Date | 2010-08-26 |
United States Patent
Application |
20100216036 |
Kind Code |
A1 |
SHIMA; Noriko |
August 26, 2010 |
NON-AQUEOUS LIQUID ELECTROLYTE AND NON-AQUEOUS LIQUID ELECTROLYTE
SECONDARY BATTERY USING THE SAME
Abstract
A non-aqueous liquid electrolyte secondary battery comprising a
anode electrode and a cathode electrode, capable of intercalating
and deintercalating lithium ions, and a non-aqueous liquid
electrolyte, having high charging capacity, capable of maintaining
excellent characteristics over a long period of time and excellent
in discharge capacity retention in particular, is provided. The
non-aqueous liquid electrolyte contains at least one of: (i) a
compound represented by the general formula (I) below and a
saturated cyclic carbonate compound; (ii) a compound represented by
the general formula (II) below; and (iii) a compound represented by
the general formula (III-1) below. ##STR00001## (In the above
formula (I), n represents an integer which is greater than or equal
to 3, m represents an integer which is greater than or equal to 1,
and the sum of n and m is greater than or equal to 5. All or part
of the hydrogen atoms may be substituted with a fluorine atom.)
##STR00002## (In the above formula (II), X represents --SO.sub.2 or
--SO--, and R.sup.1 to R.sup.6 each represent, independently of
each other, an unsubstituted alkyl group or halogen-substituted
alkyl group.) A-N.dbd.C.dbd.O (III-1) (In the above formula
(III-1), A represents an element or group other than a
hydrogen.)
Inventors: |
SHIMA; Noriko; (Ibaraki,
JP) |
Correspondence
Address: |
OBLON, SPIVAK, MCCLELLAND MAIER & NEUSTADT, L.L.P.
1940 DUKE STREET
ALEXANDRIA
VA
22314
US
|
Assignee: |
Mitsubishi Chemical
Corporation
Minato-ku
JP
|
Family ID: |
37570260 |
Appl. No.: |
12/713750 |
Filed: |
February 26, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11955692 |
Dec 13, 2007 |
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12713750 |
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PCT/JP2006/309423 |
May 10, 2006 |
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11955692 |
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Current U.S.
Class: |
429/338 |
Current CPC
Class: |
H01M 2300/0028 20130101;
H01M 10/0567 20130101; Y02E 60/10 20130101; H01M 10/0525
20130101 |
Class at
Publication: |
429/338 |
International
Class: |
H01M 6/16 20060101
H01M006/16 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 23, 2005 |
JP |
2005-183846 |
Claims
1. A non-aqueous liquid electrolyte to be used for a non-aqueous
liquid electrolyte secondary battery comprising a anode electrode
and a cathode electrode, capable of intercalating and
deintercalating lithium ions, and the non-aqueous liquid
electrolyte, the anode electrode containing a anode electrode
active material having at least one kind of atom selected from the
group consisting of Si atom, Sn atom and Pb atom, wherein said
non-aqueous liquid electrolyte contains a carbonate having at least
either an unsaturated bond or a halogen atom, and also contains at
least one of: (i) a compound represented by the general formula (I)
below and a saturated cyclic carbonate compound; (ii) a compound
represented by the general formula (II) below; and (iii) a compound
represented by the general formula (III-1) below. ##STR00044## (In
the above formula (I), n represents an integer which is greater
than or equal to 3, m represents an integer which is greater than
or equal to 1, and the sum of n and m is greater than or equal to
5. All or part of the hydrogen atoms may be substituted with a
fluorine atom.) ##STR00045## (In the above formula (II), X
represents a group represented by ##STR00046## and R.sup.1 to
R.sup.6 each represent, independently of each other, an
unsubstituted alkyl group or halogen-substituted alkyl group.)
[Chemical Formula 5] A-N.dbd.C.dbd.O (III-1) (In the above formula
(III-1), A represents an element or group other than a
hydrogen.)
2. A non-aqueous liquid electrolyte as defined in claim 1, wherein
in the above general formula (I), n and m are integers different
from each other.
3. A non-aqueous liquid electrolyte as defined in claim 1 or claim
2, wherein in said non-aqueous liquid electrolyte, the
concentration of said compound represented by the general formula
(I) is 5 volume % or higher, and 95 volume % or lower.
4. A non-aqueous liquid electrolyte as defined in any one of claims
1 to 3, wherein in said non-aqueous liquid electrolyte, the
concentration of said saturated cyclic carbonate is 5 volume % or
higher, and 50 volume % or lower.
5. A non-aqueous liquid electrolyte as defined in any one of claims
1 to 4, wherein in the above general formula (II), R.sup.1 to
R.sup.6 each represent, independently of each other, an
unsubstituted or fluorine-substituted alkyl group having 1 to 3
carbon atoms.
6. A non-aqueous liquid electrolyte as defined in any one of claims
1 to 5, wherein in said non-aqueous liquid electrolyte, the
concentration of said compound represented by the general formula
(II) is 0.01 weight % or higher, and 10 weight % or lower.
7. A non-aqueous liquid electrolyte as defined in any one of claims
1 to 6, wherein said compound represented by the general formula
(III-1) is a compound selected from the compounds represented by
the general formula (III-2) below. ##STR00047## (In the above
general formula (III-2), X.sup.1 and X.sup.2 represent,
independently of each other, an element other than hydrogen, Z
represents an arbitrary element or group, m and n represent,
independently of each other, an integer greater than or equal to 1,
and when m is 2 or greater, each of Z may be the same or different
from each other.)
8. A non-aqueous liquid electrolyte as defined in any one of claims
1 to 7, wherein said compound represented by the general formula
(III-1) is a compound selected from the group represented by the
general formula (III-3) below. ##STR00048## (In the above general
formula (III-3), R represents, independently of each other, an
alkyl group or aryl group that may have a substituent. In addition,
more than one R may be connected to each other to form a ring.)
9. A non-aqueous liquid electrolyte as defined in any one of claims
1 to 8, wherein in said non-aqueous liquid electrolyte, the
concentration of said compound represented by the general formula
(III-1) is 0.01 weight % or higher, and 10 weight % or lower.
10. A non-aqueous liquid electrolyte as defined in any one of
claims 1 to 9, wherein in said non-aqueous liquid electrolyte, the
concentration of said carbonate having at least either an
unsaturated bond or a halogen atom is 0.01 weight % or higher, and
70 weight % or lower.
11. A non-aqueous liquid electrolyte as defined in any one of
claims 1 to 10, wherein said carbonate having an unsaturated bond
or a halogen atom is one or more carbonate compounds selected from
the group consisting of vinylene carbonate, vinylethylene
carbonate, fluoroethylene carbonate, difluoroethylene carbonate and
derivatives of these carbonate compounds.
12. A non-aqueous liquid electrolyte as defined in any one of
claims 1 to 11, further comprising ethylene carbonate and/or
propylene carbonate.
13. A non-aqueous liquid electrolyte as defined in any one of
claims 1 to 12, further comprising at least one additional
carbonate selected from the group consisting of dimethyl carbonate,
ethylmethyl carbonate, diethyl carbonate, methyl-n-propyl
carbonate, ethyl-n-propyl carbonate and di-n-propyl carbonate.
14. A non-aqueous liquid electrolyte to be used for a non-aqueous
liquid electrolyte secondary battery comprising a anode electrode
and a cathode electrode, capable of intercalating and
deintercalating lithium ions, and the non-aqueous liquid
electrolyte, the anode electrode containing a anode electrode
active material having at least one kind of atom selected from the
group consisting of Si atom, Sn atom and Pb atom, wherein said
non-aqueous liquid electrolyte contains a compound represented by
the general formula (I) below and a saturated cyclic carbonate
compound. ##STR00049## (In the above formula (I), n represents an
integer which is greater than or equal to 3, m represents an
integer which is greater than or equal to 1, and the sum of n and m
is greater than or equal to 5. All or part of the hydrogen atoms
may be substituted with a fluorine atom.)
15. A non-aqueous liquid electrolyte as defined in claim 14,
wherein in the above general formula (I), n and m are integers
different from each other.
16. A non-aqueous liquid electrolyte as defined in claim 14 or
claim 15, wherein in said non-aqueous liquid electrolyte, the
concentration of said compound represented by the general formula
(I) is 5 volume % or higher, and 95 volume % or lower.
17. A non-aqueous liquid electrolyte as defined in any one of
claims 14 to 16, wherein in said non-aqueous liquid electrolyte,
the concentration of said saturated cyclic carbonate is 5 volume %
or higher, and 50 volume % or lower.
18. A non-aqueous liquid electrolyte to be used for a non-aqueous
liquid electrolyte secondary battery comprising a anode electrode
and a cathode electrode, capable of intercalating and
deintercalating lithium ions, and the non-aqueous liquid
electrolyte, the anode electrode containing a anode electrode
active material having at least one kind of atom selected from the
group consisting of Si atom, Sn atom and Pb atom, wherein said
non-aqueous liquid electrolyte contains at least a compound
represented by the general formula (II) below. ##STR00050## (In the
above formula (II), X represents a group represented by
##STR00051## and R.sup.1 to R.sup.6 each represent, independently
of each other, an unsubstituted alkyl group or halogen-substituted
alkyl group.)
19. A non-aqueous liquid electrolyte as defined in claim 18,
wherein in the above general formula (II), R.sup.1 to R.sup.6 each
represent, independently of each other, an unsubstituted or
fluorine-substituted alkyl group having 1 to 3 carbon atoms.
20. A non-aqueous liquid electrolyte as defined in claim 18 or
claim 19, wherein in said non-aqueous liquid electrolyte, the
concentration of said compound represented by the formula (II) is
0.01 weight % or higher, and 10 weight % or lower.
21. A non-aqueous liquid electrolyte secondary battery comprising a
anode electrode and a cathode electrode, capable of intercalating
and deintercalating lithium ions, and a non-aqueous liquid
electrolyte, the anode electrode containing a anode electrode
active material having at least one kind of atom selected from the
group consisting of Si atom, Sn atom and Pb atom, wherein said
non-aqueous liquid electrolyte is a non-aqueous liquid electrolyte
defined in any one of claims 1 to 20.
22. A non-aqueous liquid electrolyte to be used for a non-aqueous
liquid electrolyte secondary battery comprising a anode electrode
and a cathode electrode, capable of intercalating and
deintercalating lithium ions, and the non-aqueous liquid
electrolyte, wherein said non-aqueous liquid electrolyte contains,
at least, a carbonate having at least either an unsaturated bond or
a halogen atom, and a compound represented by the general formula
(III-1) below. [Chemical Formula 12] A-N.dbd.C.dbd.O (III-1) (In
the above formula (III-1), A represents an element or group other
than a hydrogen.)
23. A non-aqueous liquid electrolyte as defined in claim 22 wherein
said compound represented by the general formula (III-1) is a
compound selected from the group represented by the general formula
(III-2) below. ##STR00052## (In the above general formula (III-2),
X.sup.1 and X.sup.2 represent, independently of each other, an
element other than hydrogen, Z represents an arbitrary element or
group, m and n represent, independently of each other, an integer
greater than or equal to 1, and when m is 2 or greater, each of Z
may be the same or different from each other.)
24. A non-aqueous liquid electrolyte as defined in claims 22 or
claim 23, wherein said compound represented by the general formula
(III-1) is a compound selected from the group represented by the
general formula (III-3) below. ##STR00053## (In the above general
formula (III-3), R represents, independently of each other, an
alkyl group or aryl group that may have a substituent. In addition,
more than one R may be connected to each other to form a ring.)
25. A non-aqueous liquid electrolyte as defined in any one of
claims 22 to 24, wherein in said non-aqueous liquid electrolyte,
the concentration of said compound represented by the general
formula (III-1) is 0.01 weight % or higher, and 10 weight % or
lower.
26. A non-aqueous liquid electrolyte secondary battery comprising a
anode electrode and a cathode electrode, capable of intercalating
and deintercalating lithium ions, and a non-aqueous liquid
electrolyte, wherein said non-aqueous liquid electrolyte is a
non-aqueous liquid electrolyte defined in any one of claims 22 to
25.
Description
TECHNICAL FIELD
[0001] The present invention relates to a non-aqueous liquid
electrolyte and non-aqueous liquid electrolyte secondary battery
using the same.
BACKGROUND ART
[0002] Recently, with the reduction in weight and size of
electrical appliances, development of a non-aqueous liquid
electrolyte secondary battery having high energy density, for
example lithium secondary battery, has been advanced. Also, as
application field of lithium secondary battery is expanded, further
improvement in its battery characteristics has been desired.
[0003] In this situation, a secondary battery based on metal
lithium as anode electrode has been studied as a battery capable of
achieving higher capacity. However, there is a problem that metal
lithium grows as dendrite on repeated charges and discharges, and
when this reaches the cathode electrode, shortings in the battery
occurs. This has been the greatest obstacle in realizing a lithium
secondary battery based on metal lithium as anode electrode.
[0004] On the other hand, a non-aqueous liquid electrolyte
secondary battery has been proposed, in which carbonaceous material
capable of intercalating and deintercalating lithium, such as coke,
artificial graphite or natural graphite, are used for the anode
electrode in place of metal lithium. In such a non-aqueous liquid
electrolyte secondary battery, growth of metal lithium as dendrite
can be avoided and battery life and safety can be improved. When
graphite of these kinds are used as anode electrode, capacity is
known to be usually of the order of 300 mAhg.sup.-1, 500
mAhcm.sup.-3.
[0005] Recently, proposals have been made for the anode electrode
active material based on simple metal element capable of forming an
alloy with lithium such as Si, Sn and Pb, an alloy containing at
least one of these metal elements, or metal compound containing
these metal elements (hereafter referred to as "anode electrode
active material containing Si, Sn, Pb and the like", as
appropriate). The capacity of these materials per unit volume is of
the order of 2000 mAhcm.sup.-3 or larger, which is about 4 times or
even larger than that of graphite. Therefore, higher capacity is
obtained by using these materials.
[0006] Although a secondary battery using anode electrode active
material containing Si, Sn, Pb and the like is suitable for
realizing higher capacity, there is a decrease in safety, and anode
electrode active material deteriorates on repeated charges and
discharges, leading to reduced charge-discharge efficiency and
deterioration of cycle characteristics.
[0007] Therefore, in order to secure safety and prevent a decrease
in discharge capacity, a proposal has been made to include cyclic
carbonate ester or a polymer of carbonate ester and phosphoric acid
triester in the non-aqueous liquid electrolyte used for a secondary
battery (Patent Document 1). Furthermore, a proposal has been made
to add, in the non-aqueous liquid electrolyte, a heterocyclic
compound having sulfur atom and/or oxygen atom in the ring
structure and to form a protective layer on the surface of the
anode electrode active material, thus improving charge-discharge
cycle characteristics (Patent Document 2).
[0008] Furthermore, for a non-aqueous liquid electrolyte secondary
battery based on various anode electrode material, a liquid
electrolyte was proposed to which various compounds are added in
addition to its electrolyte and main solvent, in order to improve
such characteristics as load characteristics, cycle
characteristics, storage characteristics and low-temperature
characteristics.
[0009] For example, in order to suppress decomposition of liquid
electrolyte of a non-aqueous liquid electrolyte secondary battery
based on graphite anode electrode, a carbonate derivative having an
unsaturated bond has been proposed such as an liquid electrolyte
containing vinylene carbonate and its derivative (for example,
Patent Document 3), or a liquid electrolyte containing ethylene
carbonate derivative having non-conjugated unsaturated bond in its
side chain (for example, Patent Document 4).
[0010] In the liquid electrolyte containing these compounds, the
above-mentioned compounds are reduced and decomposed on the surface
of the anode electrode and a protective layer is formed, which
inhibits excessive decomposition of the liquid electrolyte. A
halogen-containing carbonate was also proposed for the same purpose
(for example Patent Document 5).
[0011] [Patent Document 1] Japanese Patent Application Laid-Open
Publication No. H11-176470
[0012] [Patent Document 2] Japanese Patent Application Laid-Open
Publication No.2004-87284
[0013] [Patent Document 3] Japanese Patent Application Laid-Open
Publication No H8-45545
[0014] [Patent Document 4] Japanese Patent Application Laid-Open
Publication No.2000-40526
[0015] [Patent Document 5] Japanese Patent Application Laid-Open
Publication No. H11-195429
DISCLOSURE OF THE INVENTION
Problem to Be Solved by the Invention
[0016] Previous secondary batteries described in Patent Documents 1
and 2 use an element such as Si as anode electrode material.
Although high capacity was thereby obtained, they were inadequate
with respect to performance on longer-term charge-discharge cycle
and, especially, discharge capacity retention discharge capacity
retention.
[0017] Technologies descried in Patent Documents 3 to 5 were also
inadequate with respect to cycle characteristics (discharge
capacity retention discharge capacity retention). Therefore,
further improvement in cycle characteristics (discharge capacity
retention) is urgently needed for non-aqueous liquid electrolyte
secondary battery based on various anode electrode material.
[0018] The present invention has been made to solve the above
problems.
[0019] Namely, a purpose of the present invention is to provide a
non-aqueous liquid electrolyte secondary battery, having high
charging capacity, capable of maintaining excellent characteristics
over a long period of time and excellent in cycle characteristics
(discharge capacity retention) in particular, and a non-aqueous
liquid electrolyte to be used for it, in a non-aqueous liquid
electrolyte secondary battery based on a anode electrode active
material having at least one kind of atom selected from the group
consisting of Si atom, Sn atom and Pb atom.
[0020] Another purpose of the present invention is to provide a
non-aqueous liquid electrolyte secondary battery, having high
charging capacity, capable of maintaining excellent characteristics
over a long period of time and excellent in cycle characteristics
(discharge capacity retention) in particular, and a non-aqueous
liquid electrolyte to be used for it, in a non-aqueous liquid
electrolyte secondary battery which uses various materials such as
graphite as anode electrode active material.
Means for Solving the Problem
[0021] The present inventors made an extensive effort to solve the
above problems and have found that it is possible to solve the
problems by incorporating in the non-aqueous liquid electrolyte a
carbonate having at least either an unsaturated bond or a halogen
atom and at least one component of (i) to (iii) described later
(specific component), in a non-aqueous liquid electrolyte secondary
battery based on a anode electrode active material having at least
one kind of atom selected from the group consisting of Si atom, Sn
atom and Pb atom. It was also found that component (i) and
component (ii) are effective without being combined with the
specific carbonate, and that the effect of component (iii) is not
limited to the secondary battery which uses the above specific
anode electrode active material but the same effect is also
exhibited for the secondary battery based on various anode
electrode active material such as graphite material. These findings
led to the completion of the present invention.
[0022] One subject matter of the present invention is a non-aqueous
liquid electrolyte to be used for a non-aqueous liquid electrolyte
secondary battery comprising a anode electrode and a cathode
electrodecathode electrode, capable of intercalating and
deintercalating lithium ions, and the non-aqueous liquid
electrolyte, the anode electrode containing a anode electrode
active material having at least one kind of atom selected from the
group consisting of Si atom, Sn atom and Pb atom, wherein said
non-aqueous liquid electrolyte contains a carbonate having at least
either an unsaturated bond or a halogen atom, and also contains at
least one of: (i) a compound represented by the general formula (I)
below and a saturated cyclic carbonate compound; (ii) a compound
represented by the general formula (II) below; and (iii) a compound
represented by the general formula (III-1) below.
##STR00003##
[0023] (In the above formula (I), n represents an integer which is
greater than or equal to 3, m represents an integer which is
greater than or equal to 1, and the sum of n and m is greater than
or equal to 5. All or part of the hydrogen atoms may be substituted
with a fluorine atom.)
##STR00004##
(In the above formula (II), X represents a group represented by
##STR00005##
and R.sup.1 to R.sup.6 each represent, independently of each other,
an unsubstituted alkyl group or halogen-substituted alkyl
group.)
[Chemical Formula 5]
A-N.dbd.C.dbd.O (III-1)
(In the above formula (III-1), A represents an element or group
other than a hydrogen.)
[0024] It is preferable that, in the above general formula (I), n
and m are integers different from each other (Claim 2).
[0025] It is preferable that, in said non-aqueous liquid
electrolyte, the concentration of said compound represented by the
general formula (I) is 5 volume % or higher, and 95 volume or lower
(claim 3).
[0026] It is preferable that, in said non-aqueous liquid
electrolyte, the concentration of said saturated cyclic carbonate
is 5 volume .degree. I or higher, and 50 volume % or lower (Claim
4).
[0027] It is preferable that, in the above general formula (II),
R.sup.1 to R.sup.6 each represent, independently of each other, an
unsubstituted or fluorine-substituted alkyl group having 1 to 3
carbon atoms (Claim 5).
[0028] It is preferable that, in said non-aqueous liquid
electrolyte, the concentration of said compound represented by the
general formula (II) is 0.01 weight % or higher, and 10 weight % or
lower (Claim 6).
[0029] It is preferable that said compound represented by the
general formula (III-1) is a compound selected from the compounds
represented by the general formula (III-2) below (Claim 7).
##STR00006##
[0030] (In the above general formula (III-2), [0031] X.sup.1 and
X.sup.2 represent, independently of each other, an element other
than hydrogen, [0032] Z represents an arbitrary element or group,
[0033] m and n represent, independently of each other, an integer
greater than or equal to 1, and [0034] when m is 2 or greater, each
of Z may be the same or different from each other.)
[0035] It is preferable that said compound represented by the
general formula (III-1) is a compound selected from the compounds
represented by the general formula (III-3) below (Claim 8).
##STR00007##
(In the above general formula (III-3), R represents, independently
of each other, an alkyl group or aryl group that may have a
substituent. In addition, more than one R may be connected to each
other to form a ring.)
[0036] It is preferable that, in said non-aqueous liquid
electrolyte, the concentration of said compound represented by the
general formula (III-1) is 0.01 weight % or higher, and 10 weight %
or lower (Claim 9).
[0037] It is preferable that, in said non-aqueous liquid
electrolyte, the concentration of said carbonate having at least
either an unsaturated bond or a halogen atom is 0.01 weight % or
higher, and 70 weight % or lower (Claim 10).
[0038] It is preferable that said carbonate having an unsaturated
bond or a halogen atom is one or more carbonates selected from the
group consisting of vinylene carbonate, vinylethylene carbonate,
fluoroethylene carbonate, difluoroethylene carbonate and
derivatives of these compounds (Claim 11).
[0039] It is preferable that it further comprises ethylene
carbonate and/or propylene carbonate (Claim 12).
[0040] It is preferable that it further comprises at least one
additional carbonate selected from the group consisting of dimethyl
carbonate, ethylmethyl carbonate, diethyl carbonate,
methyl-n-propyl carbonate, ethyl-n-propyl carbonate and di-n-propyl
carbonate (Claim 13).
[0041] Another subject matter of the present invention is a
non-aqueous liquid electrolyte to be used for a non-aqueous liquid
electrolyte secondary battery comprising a anode electrode and a
cathode electrodecathode electrode, capable of intercalating and
deintercalating lithium ions, and the non-aqueous liquid
electrolyte, the anode electrode containing a anode electrode
active material having at least one kind of atom selected from the
group consisting of Si atom, Sn atom and Pb atom, wherein said
non-aqueous liquid electrolyte contains a compound represented by
the general formula (I) below and a saturated cyclic carbonate
(Claim 14).
##STR00008##
(In the above formula (I), [0042] n represents an integer which is
greater than or equal to 3, m represents an integer which is
greater than or equal to 1, and the sum of n and m is greater than
or equal to 5.
[0043] All or part of the hydrogen atoms may be substituted with a
fluorine atom.)
[0044] It is preferable that, in the above general formula (I), n
and m are integers different from each other (Claim 15).
[0045] It is preferable that, in said non-aqueous liquid
electrolyte, the concentration of said compound represented by the
general formula (I) is 5 volume % or higher, and 95 volume % or
lower (Claim 16).
[0046] It is preferable that, in said non-aqueous liquid
electrolyte, the concentration of said saturated cyclic carbonate
is 5 volume % or higher, and 50 volume % or lower (Claim 17).
[0047] Still another subject matter of the present invention is a
non-aqueous liquid electrolyte to be used for a non-aqueous liquid
electrolyte secondary battery comprising a anode electrode and a
cathode electrodecathode electrode, capable of intercalating and
deintercalating lithium ions, and the non-aqueous liquid
electrolyte, the anode electrode containing a anode electrode
active material having at least one kind of atom selected from the
group consisting of Si atom, Sn atom and Pb atom,
[0048] wherein said non-aqueous liquid electrolyte contains at
least a compound represented by the general formula (II) below
(Claim 18).
##STR00009##
(In the above formula (II), [0049] X represents a group represented
by
##STR00010##
[0049] and R.sup.1 to R.sup.6 each represent, independently of each
other, an unsubstituted alkyl group or halogen-substituted alkyl
group.)
[0050] It is preferable that, in the above general formula (II),
R.sup.1 to R.sup.6 each represent, independently of each other, an
unsubstituted or fluorine-substituted alkyl group having 1 to 3
carbon atoms (Claim 19).
[0051] It is preferable that, in said non-aqueous liquid
electrolyte, the concentration of said compound represented by the
formula (II) is 0.01 weight % or higher, and 10 weight % or lower
(Claim 20).
[0052] Still another subject matter of the present invention is a
non-aqueous liquid electrolyte secondary battery comprising a anode
electrode and a cathode electrodecathode electrode, capable of
intercalating and deintercalating lithium ions, and a non-aqueous
liquid electrolyte, the anode electrode containing a anode
electrode active material having at least one kind of atom selected
from the group consisting of Si atom, Sn atom and Pb atom, wherein
said non-aqueous liquid electrolyte is a non-aqueous liquid
electrolyte defined in any one of claims 1 to 20 (Claim 21).
[0053] Still another subject matter of the present invention is a
non-aqueous liquid electrolyte to be used for a non-aqueous liquid
electrolyte secondary battery comprising a anode electrode and a
cathode electrodecathode electrode, capable of intercalating and
deintercalating lithium ions, and the non-aqueous liquid
electrolyte, wherein said non-aqueous liquid electrolyte contains,
at least, a carbonate having at least either an unsaturated bond or
a halogen atom, and a compound represented by the general formula
(III-1) below (Claim 22).
[Chemical Formula 12]
A-N.dbd.C.dbd.O (III-1)
[0054] (In the above formula (III-1), A represents an element or
group other than a hydrogen.)
[0055] It is preferable that said compound represented by the
general formula (III-1) is a compound selected from the group
represented by the general formula (III-2) below (Claim 23).
##STR00011##
(In the above general formula (III-2), [0056] X.sup.1 and X.sup.2
represent, independently of each other, an element other than
hydrogen, [0057] Z represents an arbitrary element or group, [0058]
m and n represent, independently of each other, an integer greater
than or equal to 1, and [0059] when m is 2 or greater, each of Z
may be the same or different from each other.)
[0060] It is preferable that said compound represented by the
general formula (III-1) is a compound selected from the group
represented by the general formula (III-3) below (Claim 24).
##STR00012##
(In the above general formula (III-3), [0061] R represents,
independently of each other, an alkyl group or aryl group that may
have a substituent. In addition, more than one R may be connected
to each other to form a ring.)
[0062] It is preferable that, in said non-aqueous liquid
electrolyte, the concentration of said compound represented by the
general formula (III-1) is 0.01 weight % or higher, and 10 weight %
or lower (Claim 25).
[0063] Still another subject matter of the present invention is a
non-aqueous liquid electrolyte secondary battery comprising a anode
electrode and a cathode electrodecathode electrode, capable of
intercalating and deintercalating lithium ions, and anon-aqueous
liquid electrolyte, wherein said non-aqueous liquid electrolyte is
a non-aqueous liquid electrolyte defined in any one of claims 22 to
25 (Claim 26).
Advantageous Effects of the Invention
[0064] The non-aqueous liquid electrolyte secondary battery of the
present invention has high charge capacity and maintains an
excellent property over a long period. It is excellent especially
in discharge capacity retention.
BEST MODES FOR CARRYING OUT THE INVENTION
[0065] The present invention will be explained in detail below. The
explanation given below indicates one example of each aspect of the
invention (representative example) and by no means restrictive. Any
modifications can be added thereto insofar as they do not depart
from the scope of the invention.
[I. First Non-Aqueous Liquid Electrolyte]
[0066] First, explanation will be given on the non-aqueous liquid
electrolyte related to the first subject of the present invention
(hereafter referred to as "first non-aqueous liquid electrolyte of
the present invention" as appropriate).
[0067] The first non-aqueous liquid electrolyte of the present
invention is the non-aqueous liquid electrolyte to be used for a
non-aqueous liquid electrolyte secondary battery comprising a anode
electrode and a cathode electrode, capable of intercalating and
deintercalating lithium ions, and a non-aqueous liquid electrolyte,
the anode electrode containing a anode electrode active material
having at least one kind of the atom selected from the group
consisting of Si atom, Sn atom and Pb atom.
[0068] The first non-aqueous liquid electrolyte of the present
invention usually comprises, as its main components, an electrolyte
and non-aqueous solvent to dissolve it, similarly to a non-aqueous
liquid electrolyte generally used. It further comprises at least
one of the components of (i) to (iii) described later (hereafter
referred to as "specific component" as appropriate), and a
carbonate having at least either an unsaturated bond or a halogen
atom (hereafter referred to as "specific carbonate" as
appropriate). It may contain other components such as an
additive.
[0069] In the following description, explanation will be given,
first, on the specific component and specific carbonate, followed
by the electrolyte and the non-aqueous solvent. Other components
will also be touched upon.
[0070] [I-1. Specific Component]
[0071] The specific component of the present invention is at least
one of the components of (i) to (iii) described below.
[0072] Component (i): a compound represented by the general formula
(I) described later and a saturated cyclic carbonate compound.
[0073] Component (ii): a compound represented by the general
formula (II) described later.
[0074] Component (iii): a compound represented by the general
formula (III-1) described later.
[0075] In the following description, an effort will be made to make
the explanation easier. When it is necessary to differentiate the
first non-aqueous liquid electrolytes of the present invention
containing component (i), component (ii) and component (iii), they
will be referred to as "non-aqueous liquid electrolyte (I)",
"non-aqueous liquid electrolyte (II)" and "non-aqueous liquid
electrolyte (III)", respectively. When no differentiation is
necessary, they will be referred to simply as "first non-aqueous
liquid electrolyte of the present invention".
[0076] The first non-aqueous liquid electrolyte of the present
invention may contain any one of the components of (i) to (iii)
singly, or may contain two or more components in any combination
and in any ratio. Therefore, when reference is made to "non-aqueous
liquid electrolyte (I)", it is to be understood that it implies not
only the solution containing component (i) alone but also the
solution further containing component (ii) and/or component (iii).
The same applies to the other cases.
[0077] In the following, components (i) to (iii) will be
explained.
[0078] <I-1-1. Component (i)>
[0079] Component (i) is a combination of a compound represented by
the general formula (I) described later (hereinafter abbreviated as
"specific compound (I)" as appropriate) and a saturated cyclic
carbonate compound.
[0080] I-1-1a. Specific Compound (I):
[0081] Specific compound (1) is a linear carbonatelinear carbonate
represented by the general formula (I) below.
##STR00013##
(In the above formula (I), n represents an integer which is greater
than or equal to 3, m represents an integer which is greater than
or equal to 1, and the sum of n and m is greater than or equal to
5. All or part of the hydrogen atoms may be substituted with a
fluorine atom.)
[0082] In the general formula (I) above, the number of carbon atoms
n in the group --C.sub.nH.sub.2n+1 (hereafter referred to "first
substituent" as appropriate) is usually 3 or more, and usually 6 or
less, preferably 5 or less. When n exceeds this upper limit, the
viscosity of the non-aqueous liquid electrolyte tends to
increase.
[0083] When the number of carbon atoms n of the first substituent
is 3 or more, chemical reactivity of the linear carbonatelinear
carbonate towards anode electrode active material containing the
above-mentioned metal elements becomes lower, leading to inhibition
of cycle deterioration. This is the reason the number of carbon
atoms n in the first substituent of the present invention is set to
be 3 or more. Carbonates with small molecular weight are highly
reactive chemically and cycle deterioration is liable to occur as a
result of a side reaction. Linear carbonateLinear carbonates having
the first substituent whose n is 3 or more are high enough in
molecular weight and the above difficulty is reduced.
[0084] Concrete examples of the first substituent are: n-propyl
group, i-propyl group, n-butyl group, t-butyl group, n-pentyl
group, 1-methylbutyl group, 2-methylbutyl group, 3-methylbutyl
group, 1,2-dimethylpropyl group, 1-ethylproyl group, n-hexyl group,
1-methylpentyl group, 2-methylpentyl group, 3-methylpentyl group,
4-methylpentyl group, 1,2-dimethylbutyl group, 1,3-dimethylbutyl
group, 2,3-dimethylbutyl group, 2-ethylbutyl group and 3-ethylbutyl
group.
[0085] Of these, preferable are n-propyl group, n-butyl group and
n-hexyl group.
[0086] On the other hand, in the general formula (I) above, the
number of carbon atoms m of the group --C.sub.mH.sub.2m+1
(hereafter referred to "second substituent" as appropriate) is
usually 1 or more, and the sum of n and m is an integer which is
usually 5 or more and preferably 9 or less, more preferably 7 or
less. When the sum n+m is below this range, the chemical reactivity
of the linear carbonate becomes high due to its small molecular
weight and cycle deterioration tends to occur as a result of a side
reaction. If the sum n+m exceeds the upper limit, the solute does
not dissolve easily, making preparation of the liquid electrolyte
difficult.
[0087] Concrete examples of the second substituent are: methyl
group, ethyl group, n-propyl group, i-propyl group, n-butyl group,
t-butyl group, n-pentyl group, 1-methylbutyl group, 2-methylbutyl
group, 3-methylbutyl group, 1,2-dimethylpropyl group, 1-ethylproyl
group, n-hexyl group, 1-methylpentyl group, 2-methylpentyl group,
3-methylpentyl group, 4-methylpentyl group, 1,2-dimethylbutyl
group, 1,3-dimethylbutyl group, 2,3-dimethylbutyl group,
2-ethylbutyl group and 3-ethylbutyl group.
[0088] Of these, preferable are methyl group and ethyl group.
[0089] All or part of hydrogen atoms in the first substituent
and/or second substituent of specific compound (I) may be
substituted with a fluorine atom. Because a fluorine atom is highly
resistant against oxidation, they are preferable as substituent
element. There is no special limitation on the number of
substituted fluorine atoms in specific compound (I). Preferably, it
is 6 or less.
[0090] The molecular weight of the specific compound (I) is usually
132 or higher and usually 188 or lower, preferably 160 or lower. If
this upper limit is exceeded, dissolution of the solute tends to be
difficult.
[0091] Concrete examples of specific compound (I) are: di-n-propyl
carbonate, diisopropyl carbonate, n-propylisopropyl carbonate,
di-n-butyl carbonate, di-i-propyl carbonate, di-t-butyl carbonate,
n-butyl-i-butyl carbonate, n-butyl-t-butyl carbonate,
i-butyl-t-butyl carbonate, n-butylmethyl carbonate, i-butylmethyl
carbonate, t-butylmethyl carbonate, ethyl-n-propyl carbonate,
n-butylethyl carbonate, i-butylethyl carbonate, t-butylethyl
carbonate, n-butyl-n-propyl carbonate, i-butyl-n-propyl carbonate,
t-butyl-n-propyl carbonate, n-butyl-i-propyl carbonate,
i-butyl-i-propyl carbonate and t-butyl-i-propyl carbonate.
[0092] Concrete examples of specific compound (I) of the linear
carbonate structure in which one or more hydrogen atoms are
replaced by one or more fluorine atoms are: 4-monofluorobutylmethyl
carbonate, 4,4-difluorobutylmethyl carbonate, 4,4,4-trifluorobutyl
carbonate, methyl-3,3,4,4,4-pentafluorobutyl carbonate,
2,2,3,3,4,4,4-heptafluorobutylmethyl carbonate,
ethyl-3-monofluoropropyl carbonate, 3,3-difluoropropylethyl
carbonate, ethyl-3,3,3-trifluoropropyl carbonate,
ethyl-2,2,3,3,3-pentafluoro carbonate, 2-monofluoroethylpropyl
carbonate, 2,2-difluoroethylpropyl carbonate,
propyl-2,2,2-trifluoroethyl carbonate,
2,2,2-trifluoroethyl-3,3,3-trifluoropropyl carbonate,
3,3,3,2,2-pentafluoropropyl-2,2,2-trifluoroethyl carbonate,
3-monofluoropropylpropyl carbonate, 3,3-difluoropropylpropyl
carbonate, propyl-3,3,3-trifluoropropyl carbonate,
3,3,3,2,2-pentafluoropropylpropyl carbonate, bis-2-monofluoropropyl
carbonate, bis-2,2-difluoropropyl carbonate,
bis-2,2,2-trifluoropropyl carbonate and
bis-3,3,3,2,2-pentafluoropropyl carbonate.
[0093] In the general formula (I) above, it is preferable that the
compound is an asymmetric carbonate with n and m being different
integers. Of those compounds, preferable are methylbutyl carbonate,
ethylpropyl carbonate and ethylbutyl carbonate from the standpoint
of basic characteristics as liquid electrolyte such as viscosity
and conductivity. Furthermore, from the standpoint of battery
characteristics such as cycle characteristics, preferable are
methylbutyl carbonate, ethylpropyl carbonate, ethylbutyl carbonate
and dipropyl carbonate. Of these compounds, particularly preferable
are ethylpropyl carbonate, ethylbutyl carbonate and dipropyl
carbonate.
[0094] Specific compound (I) can be used in the first non-aqueous
liquid electrolyte (I) either singly or as a combination of more
than one kind in any combination and in any ratio.
[0095] The proportion of specific compound (I) in the first
non-aqueous liquid electrolyte (I) is usually 50 volume % or
larger, preferably 60 volume % or larger, andusually 95 volume % or
smaller, preferably 90 volume % or smaller. When the proportion of
specific compound (I) is too small, dissociation degree of a
lithium salt tends to be lower and electric conductivity of the
non-aqueous liquid electrolyte obtained also tends to be lower. On
the other hand, when the proportion of specific compound (I) is too
large, the viscosity of the non-aqueous liquid electrolyte obtained
tends to be high.
[0096] I-1-1b. Saturated Cyclic Carbonate:
[0097] Examples of saturated cyclic carbonates to be combined with
the specific compound (I) above include ethylene carbonate,
propylene carbonate and butylene carbonate. Any hydrogen atom in
these cyclic carbonates maybe substituted with fluorine atom.
[0098] Examples of compounds derived from the above cyclic
carbonates by replacing one or more hydrogen atoms with one or more
fluorine atoms are: fluoroethylene carbonate, chloroethylene
carbonate, 4,4-difluoroethylene carbonate, 4,5-difluoroethylene
carbonate, 4,4-dichloroethylene carbonate, 4,5-dichloroethylene
carbonate, 4-fluoro-4-methylethylene carbonate,
4-chloro-4-methylethylene carbonate, 4,5-difluoro-4-methylethylene
carbonate, 4,5-dichloro-4-methylethylene carbonate,
4-fluoro-5-methylethylene carbonate, 4-chloro-5-methylethylene
carbonate, 4,4-difluoro-5-methylethylene carbonate,
4,4-dichloro-5-methylethylene carbonate, 4-(fluoromethyl)-ethylene
carbonate, 4-(chloromethyl)-ethylene carbonate,
4-(difluoromethyl)-ethylene carbonate, 4-(dichloromethyl)ethylene
carbonate, 4-(trifluoromethyl)-ethylene carbonate,
4-(trichloromethyl)-ethylene carbonate,
4-(trifluoromethyl)-4-fluoroethylene carbonate,
4-(chloromethyl)-4-chloroethylene carbonate,
4-(fluoromethyl)-5-fluoroethylene carbonate,
4-(chloromethyl)-5-chloroethylene carbonate,
4-fluoro-4,5-dimethylethylene carbonate,
4-chloro-4,5-dimethylethylene carbonate,
4,5-difluoro-4,5-dimethylethylene carbonate,
4,5-dichloro-4,5-dimethylethylene carbonate,
4,4-difluoro-5,5-dimethylethylene carbonate and
4,4-dichloro-5,5-dimethylethylene carbonate.
[0099] Of these, preferable are ethylene carbonate, propylene
carbonate, fluoroethylene carbonate, 4,4-difluoroethylene
carbonate, 4,5-difluoroethylene carbonate and
4-(fluoromethyl)-ethylene carbonate, because the solute can be
dissolved easily due to their high dielectric constant and improved
cycle characteristics of the battery can be expected.
[0100] These saturated cyclic carbonates can be used either singly
or as a combination of more than one kind in any combination and in
any ratio.
[0101] The proportion of the saturated cyclic carbonate in the
non-aqueous liquid electrolyte (I) is usually 5 volume % or larger,
preferably 10 volume % or larger, andusually 50 volume % or
smaller, preferably 40 volume % or smaller. When the proportion of
the saturated cyclic carbonate is too small, dissolution of the
solute tends to be difficult. On the other hand, when the
proportion is too large, the viscosity of the non-aqueous liquid
electrolyte obtained tends to be high.
[0102] I-1-1c. Composition Ratio of Specific Compound (I) and
Saturated Cyclic Carbonate
[0103] The non-aqueous liquid electrolyte (I) contains the linear
carbonate represented by the general formula (I) (specific compound
(I)), saturated cyclic carbonate and specific carbonate described
later. Of these compounds, specific carbonate is added to the
non-aqueous liquid electrolyte (I) as an additive. Therefore, the
composition ratio here refers to the ratio of specific compound (I)
and saturated cyclic carbonate (hereafter, in the explanation of
non-aqueous liquid electrolyte (I), these may sometimes be termed
"non-aqueous solvent" collectively).
[0104] As preferable combination of the non-aqueous solvent in the
non-aqueous liquid electrolyte (I) can be cited the following (a)
and (b): [0105] (a) Combination of the specific compound and the
saturated cyclic carbonate. [0106] (b) Combination of the specific
carbonate, the saturated cyclic carbonate and other linear
carbonate described later as desirable non-aqueous solvent.
[0107] As described previously, preferable content of specific
compound (I) in the non-aqueous liquid electrolyte (I) is usually
50 volume % or higher, preferably 60 volume % or higher, and
usually 95 volume % or lower, preferably 90 volume % or lower.
Preferable content of the saturated cyclic carbonate in the
non-aqueous liquid electrolyte (I) is usually 5 volume % or higher,
preferably 10 volume %, or higher, and usually 50 volume % or
lower, preferably 40 volume % or lower. Even when other linear
carbonate is also contained in the non-aqueous liquid electrolyte
(I), volume ratio of specific compound (I) and the saturated cyclic
carbonate is preferably 50:50 to 95:5, more preferably 60:40 to
90:10. When the ratio of the linear carbonate is too low, the
viscosity of the non-aqueous liquid electrolyte obtained increases.
When the ratio is too high, dissociation degree of a lithium salt
decreases and electric conductivity of the non-aqueous liquid
electrolyte obtained may become low.
[0108] The volume ratio of the other linear carbonate to the sum of
specific carbonate (I) and the saturated cyclic carbonate is
usually 30 volume % or lower, preferably 25 volume % or lower.
Inclusion of the other linear carbonate in the non-aqueous liquid
electrolyte (I) is helpful in making a solute easily soluble even
when the solute is difficult to dissolve with specific carbonate
(I) and the saturated cyclic carbonate alone. However, when the
ratio exceeds this above limit, cycle characteristics may
deteriorate.
[0109] In the non-aqueous liquid electrolyte (I), particularly
preferable combination and its volume ratio of non-aqueous
solvents, although these are not intended to be exhaustive, are as
described below. [0110] (1) Ethylene carbonate (EC) and
ethyl-n-propyl carbonate (EPC) [0111] EC:EPC=10:90 to 40:60, more
preferably 20:80 to 30:70 [0112] (2) EC and dipropyl carbonate
(DPC) [0113] EC:DPC=10:90 to 40:60, more preferably 20:80 to 30:70
[0114] (3) EC and ethyl-n-butyl carbonate (EBC) [0115] EC:EBC=10:90
to 40:60, more preferably 20:80 to 30:70 [0116] (4) Fluoroethylene
carbonate (FEC) and EC and ethyl-n-propyl carbonate (EPC) [0117]
FEC:EC:EPC=5:5:90 to 25:25:50, more preferably 10:10:80 to 20:20:60
[0118] (5) FEC and EPC [0119] FEC:EPC=10:90 to 40:60, more
preferably 20:80 to 30:70 [0120] (6) FEC and DPC [0121]
FEC:DPC=10:90 to 40:60, more preferably 20:80 to 30:70 [0122] (7)
FEC and EBC [0123] FEC:EBC=10:90 to 40:60, more preferably 20:80 to
30:70
[0124] In the combinations of (1) to (7) above, still another
linear carbonate may be added such as dimethyl carbonate (DMC),
ethylmethylmethyl carbonate (EMC) and diethyl carbonate (DEC).
Examples include the following combination and volume ratio. [0125]
(8) EC and EPC and DEC [0126] EC:EPC:DEC=10 to 40:40 to 80:10 to 30
[0127] (9) EC and DPC and DEC [0128] EC:DPC:DEC=10 to 40:40 to
80:10 to 30 [0129] (10) FEC and EPC and DEC [0130] FEC:EPC:DEC=10
to 40:40 to 80:10 to 30 [0131] (11) FEC and DPC and DEC [0132]
FEC:DPC:DEC=10 to 40:40 to 80:10 to 30
[0133] In the above examples of preferable combination, any
hydrogen atom of the alkyl groups of EPC, DPC and EBC may be
replaced by a fluorine atom.
[0134] In addition to the above combination, it is preferable that
the specific carbonate to be described later is added to the
non-aqueous liquid electrolyte (I) in the amount of usually 0.01
weight % or larger, preferably 0.1 weight % or larger, more
preferably 0.3 weight % or larger, and usually 50 weight % or
smaller, preferably 40 weight % or smaller, more preferably 30
weight % or smaller. The rationale of this range will be mentioned
later.
[0135] I-1-1d. Others:
[0136] The charge-discharge cycle characteristics are improved in
the non-aqueous liquid electrolyte (I) containing the
above-mentioned specific linear carbonate (specific compound (I)),
saturated cyclic carbonate and specific carbonate described later.
The detailed reason is not clear, but inferred as follows.
[0137] The reactivity of the specific compound (I) in the
non-aqueous liquid electrolyte (I) towards anode electrode active
material containing metal element mentioned above becomes low by
the presence of alkyl group or fluoroalkyl group with 3 or more
carbon atoms, leading to suppression of a side reaction and
inhibition of deterioration of cycle characteristics. The similar
effect can be obtained when the total number of carbon atoms of
alkyl or fluoroalkyl groups of the linear carbonate is 5 or more.
Thus, under the condition where the side reaction due to the linear
carbonate is suppressed, an effective protective layer is formed by
the specific carbonate described later. Solubility of the
electrolyte is enhanced by the saturated cyclic carbonate and
improvement in charge-discharge cycle characteristics follows.
[0138] This advantageous effect of the present invention derived
from the combined use of the specific compound (I), saturated
cyclic carbonate and specific carbonate described later is
characteristic of the use of anode electrode active material having
at least one kind of atom selected from the group consisting of Si
atom, Sn atom and Pb atom. As will be described later in [Example
.cndot. Comparative Example I], improvement in long term
charge-discharge cycle characteristics can not be realized when
carbon material is used as anode electrode active material.
[0139] <I-1-2. Component (ii)>
[0140] Component (ii) is a compound represented by the general
formula (II) below (hereafter referred to as "specific compound
(II)" as appropriate).
##STR00014##
(In the above formula (II), X represents a group represented by
##STR00015##
(This may be hereinafter described as "--SO.sub.2--".) or
##STR00016##
(This may be hereinafter described as "--SO--".) [0141] , and
R.sup.1 to R.sup.6 each represent, independently of each other, an
unsubstituted alkyl group or halogen-substituted alkyl group.)
[0142] In the general formula (II) above, X represents --SO.sub.2--
or --SO--above. When it represents --SO.sub.2--, the compound is a
sulfate ester, assuming a sulfate structure. When it represents
--SO--, the compound is a sulfite ester, assuming a sulfite
structure.
[0143] In the general formula (II) above, R.sup.1 to R.sup.6 each
represent, independently of each other, an unsubstituted alkyl
group or halogen-substituted alkyl group. The number of carbon
atoms of this alkyl group is usually one or more and 6 or less,
preferably 3 or less. If n is too large, the effect of specific
compound (II) per unit weight is not significant, making the
presence of the compound meaningless.
[0144] Concrete examples of alkyl group are: methyl group, ethyl
group, n-propyl group, i-propyl group, n-butyl group, s-butyl
group, i-butyl group, t-butyl group, n-pentyl group, 1-methylbutyl
group, 2-methylbutyl group, 3-methylbutyl group, 1,2-dimethylpropyl
group, 1-ethylpropyl group, n-hexyl group, 1-methylpentyl group,
2-methylpentyl group, 3-methylpentyl group, 4-methylpentyl group,
1,2-dimethylbutyl group, 1,3-dimethylbutyl group, 2,3-dimethylbutyl
group, 2-ethylbutyl group and 3-ethylbutyl group.
[0145] Of these, preferable are methyl group, ethyl group and
n-propyl group.
[0146] When R.sup.1 to R.sup.6 are halogen-substituted alkyl
groups, substitution may be for all the hydrogen atoms of the alkyl
group or for part of the hydrogen atoms. Fluorine atom and chlorine
atom are cited as halogen atom. Fluorine atom is preferable because
of its high resistance against oxidation. No particular limitation
is imposed on the number of substituted halogen atoms. Preferable
is 6 or less, more preferable is 3 or less, per one alkyl
group.
[0147] Examples of halogen-substituted alkyl group, where halogen
atom is fluorine atom, are: fluoromethyl group, 1-fluoroethyl
group, 2-fluoroethyl group, 1-fluoro-n-propyl group,
2-fluoro-n-propyl group, 3-fluoro-n-propyl group, difluoromethyl
group, 1,1-difluoroethyl group, 1,2-difluoroethyl group,
2,2-difluoroethyl group, 1,1-difluoro-n-propyl group,
1,2-difluoro-n-propyl group, 1,3-difluoro-n-propyl group,
2,2-difluoro-n-propyl group, 2,3-difluoro-n-propyl group,
3,3-difluoro-n-propyl group, trifluoromethyl group,
1,1,2-trifluoroethyl group, 1,2,2-trifluoroethyl group,
2,2,2-trifluoroethyl group, 1,1,2-trifluoro-n-propyl group,
1,2,2-trifluoro-n-proppyl group, 1,1,3-trifluoro-n-propyl group,
1,2,3-trifluoro-n-propyl group, 1,3,3-trifluoro-n-propyl group,
2,2,3-trifluoro-n-propyl group, 2,3,3-trifluoro-n-propyl group and
3,3,3-trifluoro-n-propyl group.
[0148] The groups derived from the above-mentioned groups by
substituting any fluorine atom with any other halogen atom can also
be cited as halogen-substituted alkyl groups.
[0149] Of these groups, preferable from the standpoint of stability
and ease of preparation are fluoromethyl group, trifluoromethyl
group, 2-fluoroethyl group, 2,2-difluoroethyl group,
2,2,2-trifluoroethyl group, 3-fluoro-n-propyl group and
3,3,3-trifluoro-n-propyl group.
[0150] In the general formula (II) above, R.sup.1 to R.sup.6 may be
either the same or different from one another. From the standpoint
of ease of preparation, it is preferable that they belong to the
same group.
[0151] Accordingly, as concrete examples of specific compound (II)
can be cited: silicon-containing sulfate esters such as
bis(trimethylsilyl)sulfate, bis{tris(fluoromethyl)silyl}sufate,
bis(triethylsilyl)sulfate, bis{tris(2-fluoroethyl)}sulfate,
bis{tris(2,2-difluoroethyl)}sulfate,
bis{tris(2,2,2-trifluoroethyl)}sulfate,
bis(tri-n-propyl)sulfate,bis{tris(3-fluoro-n-propyl)}sulfate and
bis{tris(3,3,3-trifluoro-n-propyl)}sulfate; and silicon-containing
sulfite esters such as bis(trimethylsilyl)sulfite,
bis{tris(fluoromethyl)silyl}sulfite, bis(triethylsilyl)sulfite,
bis{tris(2-fluoroethly)}sulfite,
bis{tris(2,2-difluoroethyl)}sulfite,
bis{tris(2,2,2-trifluoroethyl)}sulfite, bis(tri-n-propyl)sulfite,
bis{tris(3-fluoro-n-propyl)}sulfite and
bis{tris(3,3,3-trifluoro-n-propyl)}sulfite.
[0152] Of these compounds, preferable are those in which R.sup.1 to
R.sup.6 in the general formula (II) are, independently of each
other, an unsubstituted or fluorine-substituted alkyl group with 1
to 3 carbon atoms. Concrete examples are:
bis(trimethylsilyl)sulfate, bis(triethylsilyl)sulfate,
bis{tris(2-fluoroethyl)}sulfate,
bis{tris(2,2,2-trifluoroethyl)}sulfate, bis(tri-n-propyl)sulfate,
bis(trimethylsilyl)sulfite, bis(triethylsilyl)sulfite,
bis{tris(2-fluoroethly)}sulfite,
bis{tris(2,2,2-trifluoroethyl)}sulfite and
bis(tri-n-propyl)sulfite.
[0153] For these compounds, it is preferable that R.sup.1 to
R.sup.6 are the same group. Furthermore, it is particularly
preferable that, in the above formula (II), R.sup.1 to R.sup.6 are
the same group and they are an unsubstituted or
fluorine-substituted alkyl group with 1 or 2 carbon atoms. From the
standpoint of ease of technical availability, unsubstituted alkyl
groups with 1 to 2 carbon atoms are particularly preferable.
[0154] There is no special limitation on the molecular weight of
specific compound (II), insofar as the advantage of the present
invention is not significantly impaired. It is usually 100 or
larger, preferably 110 or larger. No upper limit is imposed,
although from a practical standpoint it is usually 400 or smaller,
preferably 300 or smaller, as the viscosity increases with the
molecular weight.
[0155] There is no special limitation on the method of producing
specific compound (II) and any known method can be selected and
used.
[0156] Specific compound (II), explained above, may be used in the
non-aqueous liquid electrolyte (II) either singly or as a mixture
of more than one kind in any combination and in any ratio.
[0157] There is no special limitation on the proportion of specific
compound (II) in the non-aqueous liquid electrolyte (II), insofar
as the advantage of the present invention is not significantly
impaired. The proportion is usually 0.01 weight % or larger,
preferably 0.1 weight % or larger, and usually 10 weight % or
smaller, preferably 5 weight % or smaller. If the proportion of
specific compound (II) is too small, adequate effect of improving
the cycle characteristics of the secondary battery are not
guaranteed when the non-aqueous liquid electrolyte is used for the
non-aqueous liquid electrolyte secondary battery. On the other
hand, if the proportion of specific compound (II) is too large,
chemical reactivity of the non-aqueous liquid electrolyte tends to
increase and battery characteristics of the non-aqueous liquid
electrolyte secondary battery obtained may deteriorate.
[0158] In the non-aqueous liquid electrolyte (II), there is no
special limitation on the ratio of the specific compound (II) and
specific carbonate described later. Relative weight ratio expressed
as "weight of specific compound (II)/weight of specific carbonate"
is usually 0.0001 or larger, preferably 0.001 or larger, more
preferably 0.01 or larger, and usually 1000 or smaller, preferably
100 or smaller, more preferably 10 or smaller. If the above
relative weight ratio is either too large or too small, synergistic
effect of the specific compound (II) and specific carbonate may not
be realized.
[0159] It is possible to improve the charge-discharge cycle
characteristics of the non-aqueous liquid electrolyte secondary
battery by using the non-aqueous liquid electrolyte (II) containing
the above-mentioned specific compound (II) and the specific
carbonate described later. The detailed reason is not clear, but
inferred as follows. Namely, through the reaction of both specific
compound (II) and specific carbonate contained in the non-aqueous
liquid electrolyte (II), an effective protective layer is formed on
the surface of the anode electrode active material, leading to the
suppression of side reactions. Cycle deterioration is thus
inhibited. Although detailed reason is not clear, coexistence of
the specific compound (II) and the specific carbonate in the liquid
electrolyte contributes to the improvement of the characteristics
of the protective layer in some way or other.
[0160] This advantageous effect of the present invention derived
from the combined use of the specific compound (II) and the
specific carbonate described later is characteristic of the use of
anode electrode active material having at least one kind of atom
selected from the group consisting of Si atom, Sn atom and Pb atom.
As will be described later in [Example .cndot. Comparative Example
II], improvement in long term charge-discharge cycle
characteristics can not be realized when carbon material is used as
anode electrode active material.
[0161] <I-1-3. Component (iii)>
[0162] Component (iii) is a compound represented by the general
formula (III-1) below (hereinafter abbreviated as "specific
compound (III)", as appropriate).
[Chemical Formula 19]
A-N.dbd.C.dbd.C) (III-1)
[0163] In the formula (III-1) above, A represents an arbitrary
element or group other than hydrogen. From the standpoint of
electrochemical stability, it is preferable that A is a group other
than aryl group or other than group having aryl group as
substituent. Namely, it is preferable that A is an element or group
other than aryl group and it is also preferable that A is an
element or group other than group having aryl group as
substituent.
[0164] Furthermore, from the standpoint of stability of specific
compound (III) as organic material and stability of protective
layer formed, A is preferably halogen among various elements. Of
various functional groups, A is preferably a chained or cyclic,
saturated or unsaturated alkyl group which may have a
substituent.
[0165] Of specific compounds (III), preferable are those
represented by the general formula (III-2) or (III-3) below.
##STR00017##
[0166] (In the above formula (III-2), X.sup.1 and X.sup.2
represent, independently of each other, an element other than
hydrogen and
[0167] Z represents an arbitrary element or group. M and n
represent, independently of each other, an integer greater than or
equal to 1. When m is 2 or greater, each of Z may be the same or
different from each other.)
##STR00018##
[0168] (In the above formula (III-3), R represents, independently
of each other, an alkyl group or aryl group that may have a
substituent. In addition, more than one R may be connected to each
other to form a ring.)
[0169] The formula (III-2) and (III-3) will be explained in further
detail below.
[0170] In the formula (III-2), X.sup.1 and X.sup.2 represent,
independently of each other, an element other than hydrogen. Any
element other than hydrogen can be X.sup.1 and X.sup.2, insofar as
they are consistent with the chemical structure of (III-2). As
concrete examples of preferable X.sup.I can be cited carbon atom,
sulfur atom and phosphor atom. As concrete examples of preferable
X.sup.2 can be cited oxygen atom and nitrogen atom.
[0171] In the formula (III-2), Z represents an arbitrary element or
group. Preferable concrete examples of Z include an alkyl group. Of
the alkyl group, preferable are methyl group, ethyl group,
fluoromethyl group, trifluoromethyl group, 2-fluoroethyl group and
2,2,2-trifluoroethyl group. Particularly preferable are methyl
group and ethyl group. When m is greater than or equal to 2, each
of Z may be the same or different from each other. Further, more
than one Z may be connected to each other to form a ring.
[0172] In the formula (III-2), m and n indicate an integer which is
greater than or equal to 1. As concrete examples of preferable
specific compounds expressed in the formula (III-2) can be cited
the following compounds. In the compounds shown below, each of
R.sup.1 represents, independently of each other, an alkyl group. As
concrete examples of R.sup.1, alkyl groups described as appropriate
examples of Z in the formula (III-2) can be cited.
##STR00019##
[0173] On the other hand, in the formula (III-3), R represents,
independently of each other, an alkyl group or aryl group that may
have a substituent.
[0174] When R is an alkyl group, concrete examples of R include
methyl group, ethyl group, fluoromethyl group, trifluoromethyl
group, 2-fluoroethyl group and 2,2,2-trifluoroethyl group.
Preferable are methyl group and ethyl group.
[0175] In case R is an aryl group, concrete examples include phenyl
group, o-tosyl group, m-tosyl group, p-tosyl group, o-fluorophenyl
group, m-fluorophenyl group and p-fluorophenyl group.
[0176] Each R may be identical to or different from each other.
More than one R may be connected with each other to form a
ring.
[0177] Concrete examples of specific compound (III) include the
following:
##STR00020## ##STR00021##
[0178] Specific compound (III) may be used in the non-aqueous
liquid electrolyte (III) either singly or as a mixture of more than
one kind in any combination and in any ratio.
[0179] There is no special limitation on the molecular weight of
specific compound (III), insofar as the advantage of the present
invention is not significantly impaired. It is usually 100 or
larger. Although no upper limit is imposed, it is usually 300 or
smaller, preferably 200 or smaller from a practical standpoint.
[0180] There is no special limitation on the proportion of the
specific compound (III) in the non-aqueous liquid electrolyte
(III), insofar as the advantage of the present invention is not
significantly impaired. Usually, the proportion is 0.01 weight % or
larger, preferably 0.1 weight % or larger, andusually 10 weight %
or smaller, preferably 5 weight % or smaller in the non-aqueous
liquid electrolyte (III). In case the proportion is below the
above-mentioned lower limit, adequate effect of improving cycle
characteristics of the non-aqueous liquid electrolyte secondary
battery obtained is not guaranteed when the non-aqueous liquid
electrolyte is used for the non-aqueous liquid electrolyte
secondary battery. In case the upper limit is exceeded, chemical
reactivity of the non-aqueous liquid electrolyte tends to increase
and battery characteristics of the non-aqueous liquid electrolyte
secondary battery obtained may deteriorate.
[0181] There is no special limitation on the method of producing
specific compound (III) and any known method can be used.
[0182] In the non-aqueous liquid electrolyte (III), there is no
special limitation on the ratio of specific compound (III) and the
specific carbonate described later. Relative weight ratio expressed
as "weight of specific compound (III)/weight of specific carbonate"
is usually 0.001 or larger, preferably 0.01 or larger, more
preferably 0.1 or larger, and usually 1000 or smaller, preferably
100 or smaller, more preferably 10 or smaller. If the above
relative ratio is too large or too small, synergistic effect by
combined use of specific compound (III) and the specific carbonate
may not be realized.
[0183] It is possible to improve the charge-discharge cycle
characteristics of the non-aqueous liquid electrolyte secondary
battery by using the non-aqueous liquid electrolyte (III)
containing the above-mentioned specific compound (III) and the
specific carbonate described later. The detailed reason is not
clear, but inferred as follows. Namely, through the reaction of
both specific compound (III) and the specific carbonate contained
in the non-aqueous liquid electrolyte (III), an effective
protective layer is formed on the surface of the anode electrode
active material, leading to the suppression of side reactions.
Cycle deterioration is thus inhibited.
[0184] [I-2. Specific Carbonate]
[0185] The specific carbonate of the present invention indicates a
carbonate having at least either an unsaturated bond or a halogen
atom. Namely, specific carbonate of the present invention may
contain only an unsaturated bond or only a halogen atom. It may
also contain both an unsaturated bond and a halogen atom.
[0186] There is no special limitation on the kind of carbonate
having an unsaturated bond (referred to "unsaturated carbonate" as
appropriate), insofar as it is a carbonate having carbon-to-carbon
unsaturated bond such as carbon-to-carbon double bond or
carbon-to-carbon triple bond. Any known unsaturated carbonate can
be used. A carbonate having an aromatic ring can also be regarded
as carbonate having an unsaturated bond.
[0187] As examples of the unsaturated carbonate can be cited
vinylene carbonate and its derivatives, ethylene carbonate
substituted by a substituent having an aromatic ring or
carbon-to-carbon unsaturated bond and its derivatives, phenyl
carbonates, vinyl carbonates and allyl carbonates.
[0188] Concrete examples of vinylene carbonate and its derivatives
are: vinylene carbonate, methylvinylene carbonate,
4,5-dimethylvinylene carbonate, phenylvinylene carbonate and
4,5-diphenylvinylene carbonate.
[0189] Concrete examples of ethylene carbonate substituted by a
substituent containing an aromatic ring or a carbon-to-carbon
unsaturated bond and its derivatives are: vinylethylene carbonate,
4,5-divinylethylene carbonate, phenylethylene carbonate and
4,5-diphenylethylene carbonate.
[0190] Concrete examples of phenyl carbonates are: diphenyl
carbonate, ethylphenyl carbonate, methylphenyl carbonate and
t-butylphenyl carbonate.
[0191] Concrete examples of vinyl carbonates are: divinyl carbonate
and methylvinyl carbonate.
[0192] Concrete examples of allyl carbonates are: diallyl carbonate
and allylmethyl carbonate.
[0193] Of these unsaturated carbonate compounds, preferable as
specific carbonate are vinylene carbonate and its derivatives, and
ethylene carbonate substituted by a substituent having an aromatic
ring or carbon-to-carbon unsaturated bond and its derivatives. In
particular, vinylene carbonate, 4,5-diphenylvinylene carbonate,
4,5-dimethylvinylene carbonate and vinylethylene carbonate can be
preferably used, as they form a stable interface protective
layer.
[0194] On the other hand, regarding a carbonate having a halogen
atom (abbreviated as "halogenated carbonate" as appropriate), no
special limitation exists on its kind insofar as it contains a
halogen atom. Any halogenated carbonate can be used.
[0195] Concrete examples of halogen atoms are fluorine atom,
chlorine atom, bromine atom and iodine atom. Of these, preferable
are fluorine atom and chlorine atom. Fluorine atom is particularly
preferable. There is no special limitation on the number of halogen
atoms contained in the halogenated carbonate insofar as it is one
or more, and usually 6 or less, preferably 4 or less. When the
halogenated carbonate contains more than one halogen atoms, they
can be identical to or different from each other.
[0196] Examples of halogenated carbonate include ethylene carbonate
derivatives, dimethyl carbonate derivatives, ethylmethyl carbonate
derivatives and diethyl carbonate derivatives.
[0197] Concrete examples of ethylene carbonate derivatives are:
fluoroethylene carbonate, chloroethylene carbonate,
4,4-difluoroethylene carbonate, 4,5-difluoroethylene carbonate,
4,4-dichloroethylene carbonate, 4,5-dichloroethylene carbonate,
4-fluoro-4-methylethylene carbonate, 4-chloro-4-methylethylene
carbonate, 4,5-difluoro-4-methylethylene carbonate,
4,5-dichloro-4-methylethylene carbonate, 4-fluoro-5-methylethylene
carbonate, 4-chloro-5-methylethylene carbonate,
4,4-difluoro-5-methylethylene carbonate,
4,4-dichloro-5-methylethylene carbonate, 4-(fluoromethyl)-ethylene
carbonate, 4-(chloromethyl)-ethylene carbonate,
4-(difluoromethyl)-ethylene carbonate, 4-(dichloromethyl)-ethylene
carbonate, 4-(trifluoromethyl)-ethylene carbonate,
4-(trichloromethyl)-ethylene carbonate,
4-(fluoromethyl)-4-fluoroethylene carbonate,
4-(chloromethyl)-4-chloroethylene carbonate,
4-(fluoromethyl)-5-fluoroethylene carbonate,
4-(chloromethyl)-5-chloroethylene carbonate,
4-fluoro-4,5-dimethylethylene carbonate,
4-chloro-4,5-dimethylethylene carbonate,
4,5-difluoro-4,5-dimethylethylene carbonate,
4,5-dichloro-4,5-dimethylethylene carbonate,
4,4-difluoro-5,5-dimethylethylene carbonate and
4,4-dichloro-5,5-dimethylethylene carbonate.
[0198] Concrete examples of dimethyl carbonate derivatives are:
fluoromethyl methyl carbonate, difluoromethyl methyl carbonate,
trifluoromethyl methyl carbonate, bis(fluoromethyl)carbonate, bis
(difluoro)methyl carbonate, bis (trifluoro)methyl carbonate,
chloromethylmethyl carbonate, dichloromethylmethyl carbonate,
trichloromethylmethyl carbonate, bis(chloromethyl) carbonate,
bis(dichloro)methyl carbonate and bis(trichloro)methyl
carbonate.
[0199] Concrete examples of ethylmethyl carbonate derivatives are:
2-fluoroethylmethyl carbonate, ethylfluoromethyl carbonate,
2,2-difluoroethylmethyl carbonate, 2-fluoroethylfluoromethyl
carbonate, ethyldifluoromethyl carbonate,
2,2,2-trifluoroethylmethyl carbonate, 2,2-difluoroethylfluoromethyl
carbonate, 2-fluoroethyldifluoromethyl carbonate,
ethyltrifluoromethyl carbonate, 2-chloroethylmethyl carbonate,
ethylchloromethyl carbonate, 2,2-dichloroethylmethyl carbonate,
2-chloroethylchloromethyl carbonate, ethyldichloromethyl carbonate,
2,2,2-trichloroethylmethyl carbonate, 2,2-dichloroethylchloromethyl
carbonate, 2-chloroethyldichloromethyl carbonate and
ethyltrichloromethyl carbonate.
[0200] Concrete examples of diethyl carbonate derivatives are:
ethyl-(2-fluoroethyl) carbonate,
ethyl-(2,2-difluoroethyl)carbonate, bis(2-fluoroethyl)carbonate,
ethyl-(2,2,2-trifluoroethyl)carbonate,
2,2-difluoroethyl-2'-fluoroethyl carbonate,
bis(2,2-difluoroethyl)carbonate,
2,2,2-trifluoroethyl-2'-fluoroethyl carbonate,
2,2,2-trifluoroethyl-2',2'-difluoroethyl carbonate,
bis(2,2,2-trifluoroethyl)carbonate, ethyl-(2-chloroethyl)carbonate,
ethyl-(2,2-dichloroethyl)carbonate, bis(2-chloroethyl)carbonate,
ethyl-(2,2,2-trichloroethyl)carbonate,
2,2-dichloroethyl-2'-chloroethyl carbonate, bis(2,2-dichloroethyl)
carbonate, 2,2,2-trichloroethyl-2'-chloroethyl carbonate,
2,2,2-trichloroethyl-2',2'-dichloroethyl carbonate and
bis(2,2,2-trichloroethyl) carbonate.
[0201] Of these halogenated carbonates, preferable are carbonates
containing a fluorine atom. Particularly preferable are ethylene
carbonate derivatives containing a fluorine atom. In particular,
fluoroethylene carbonate, 4-(fluoromethyl)-ethylene carbonate,
4,4-difluoroethylene carbonate and 4,5-difluoroethylene carbonate
can preferably be used, as these compounds form an interface
protective layer.
[0202] Furthermore, it is possible to use a carbonate containing
both an unsaturated bond and a halogen atom (abbreviated as
"halogenated unsaturated carbonate" as appropriate) as specific
carbonate. There is no special limitation on the halogenated
unsaturated carbonate used and any such compounds can be used
insofar as the advantage of the present invention is not
significantly impaired.
[0203] Examples of halogenated, unsaturated carbonates include
vinylene carbonate derivatives, ethylene carbonate derivatives
substituted by a substituent having an aromatic ring or
carbon-to-carbon unsaturated bond, and allyl carbonates.
[0204] Concrete examples of vinylene carbonate derivatives are:
fluorovinylene carbonate, 4-fluoro-5-methylvinylene carbonate,
4-fluoro-5-phenylvinylene carbonate, chlorovinylene carbonate,
4-chloro-5-methylvinylene carbonate and 4-chloro-5-phenylvinylene
carbonate.
[0205] Concrete examples of ethylene carbonate derivatives which is
substituted by a substituent having an aromatic ring or carbon to
carbon unsaturated bond are: 4-fluoro-4-vinylethylene carbonate,
4-fluoro-5-vinylethylene carbonate, 4,4-difluoro-4-vinylethylene
carbonate, 4,5-difluoro-4-vinylethylene carbonate,
4-chloro-5-vinylethylene carbonate, 4,4-dichloro-4-vinylethylene
carbonate, 4,5-dichloro-4-vinylethylene carbonate,
4-fluoro-4,5-divinylethylene carbonate,
4,5-difluoro-4,5-divinylethylene carbonate,
4-chloro-4,5-divinylethylene carbonate,
4,5-dichloro-4,5-divinylethylene carbonate,
4-fluoro-4-phenylethylene carbonate, 4-fluoro-5-phenylethylene
carbonate, 4,4-difluoro-5-phenylethylene carbonate,
4,5-difluoro-4-phenylethylene carbonate, 4-chloro-4-phenylethylene
carbonate, 4-chloro-5-phenylethylene carbonate,
4,4-dichloro-5-phenylethylene carbonate,
4,5-dichloro-4-phenylethylene carbonate,
4,5-difluoro-4,5-diphenylethylene carbonate and
4,5-dichloro-4,5-diphenylethylene carbonate.
[0206] Concrete examples of phenyl carbonates are:
[0207] fluoromethylphenyl carbonate, 2-fluoroethylphenyl carbonate,
2,2-difluoroethylphenyl carbonate, 2,2,2-trifluoroethylphenyl
carbonate, chloromethylphenyl carbonate, 2-chloroethylphenyl
carbonate, 2,2-dichloroethylphenyl carbonate and
2,2,2-trichloroethylphenyl carbonate.
[0208] Concrete examples of vinyl carbonates are: fluoromethylvinyl
carbonate, 2-fluoroethylvinyl carbonate, 2,2-difluoroethylvinyl
carbonate, 2,2,2-trifluoroethylvinyl carbonate, chloromethylvinyl
carbonate, 2-chloroethylvinyl carbonate, 2,2-dichloroethylvinyl
carbonate and 2,2,2-trichloroethylvinyl carbonate.
[0209] Concrete examples of allyl carbonates are: fluoromethylallyl
carbonate, 2-fluoroethylallyl carbonate, 2,2-difluoroethylallyl
carbonate, 2,2,2-trifluoroethylallyl carbonate, chloromethylallyl
carbonate, 2-chloroethylallyl carbonate, 2,2-dichloroethylallyl
carbonate and 2,2,2-trichloroethylallyl carbonate.
[0210] Of the halogenated unsaturated carbonates mentioned above,
particularly preferable as specific carbonate are one or more
compounds selected from the group consisting of vinylene carbonate,
vinylethylene carbonate, fluoroethylene carbonate,
4,5-difluoroethylene carbonate, and derivatives of these carbonate
compounds, which are highly effective when used alone.
[0211] There is no special limitation on the molecular weight of
the specific carbonate, insofar as the advantage of the present
invention is not significantly impaired. It is usually 50 or
larger, preferably 80 or larger, and usually 250 or smaller,
preferably 150 or smaller. When it is too large, the solubility of
the specific carbonate in the non-aqueous liquid electrolyte
decreases and the advantageous effect of the present invention may
not be adequately realized.
[0212] There is no special limitation on the method of producing
the specific carbonate and any known method can be selected and
used.
[0213] The specific carbonate, explained above, may be used in the
first non-aqueous liquid electrolyte of the present invention
either singly or as a mixture of more than one kind in any
combination and in any ratio.
[0214] There is no special limitation on the proportion of the
specific carbonate in the first non-aqueous liquid electrolyte of
the present invention, insofar as the advantage of the present
invention is not significantly impaired. The proportion is usually
0.01 weight % or larger, preferably 0.1 weight % or larger, more
preferably 0.3 weight % or larger, and usually 70 weight % or
smaller, preferably 50 weight % or smaller, more preferably 40
weight % or smaller. If the proportion is below the above-mentioned
lower limit, adequate effect of improving cycle characteristics of
the non-aqueous liquid electrolyte secondary battery are not
guaranteed when the first non-aqueous liquid electrolyte of the
present invention is used for the non-aqueous liquid electrolyte
secondary battery. If the upper limit is exceeded, high-temperature
storage characteristics and trickle charging characteristics of the
non-aqueous liquid electrolyte secondary battery tend to
deteriorate, leading to increased gas evolution and deterioration
of discharge capacity retention, when the first non-aqueous liquid
electrolyte of the present invention is used for the non-aqueous
liquid electrolyte secondary battery.
[0215] In the non-aqueous liquid electrolyte (I), specific compound
(I) and/or the saturated cyclic carbonate, mentioned above, may be
a carbonate having an unsaturated bond and/or a halogen atom. In
those cases, that specific compound (I) and/or saturated cyclic
carbonate can function also as the specific carbonate, and use of
additional specific carbonate is not necessary.
[0216] [I-3. Non-Aqueous Solvent]
[0217] As non-aqueous solvent contained in the first non-aqueous
liquid electrolyte of the present invention, any such solvent can
be used, insofar as the advantageous effect of the present
invention is not significantly impaired. Non-aqueous solvent may be
used either singly or as a combination of more than one kind in any
combination and in any ratio.
[0218] Examples of usually used non-aqueous solvent include: cyclic
carbonate, linear carbonate, chained and cyclic carboxylic acid
ester, chained and cyclic ether, phosphor-containing organic
solvent and sulfur-containing organic solvent.
[0219] There is no special limitation on the kind of the cyclic
carbonate. Examples of those usually used, except the specific
carbonates mentioned previously, include: ethylene carbonate,
propylene carbonate and butylene carbonate.
[0220] Of these compounds, ethylene carbonate and propylene
carbonate are preferable because they have high dielectric
constant, which effects easy dissolution of the solute, and assures
good cycle characteristics when used for the non-aqueous
electrolyte solution secondary battery. Accordingly, it is
preferable that the first non-aqueous liquid electrolyte of the
present invention contains, as non-aqueous solvent, ethylene
carbonate and/or propylene carbonate, in addition to the specific
carbonate mentioned before.
[0221] There is no special limitation on the kind of the linear
carbonate, either. Examples of those usually used, except the
specific carbonates mentioned previously, include: dimethyl
carbonate, ethylmethyl carbonate, diethyl carbonate,
methyl-n-propyl carbonate, ethyl-n-propyl carbonate and di-n-propyl
carbonate.
[0222] Therefore, it is preferable that the first non-aqueous
liquid electrolyte of the present invention contains, as
non-aqueous solvent, at least one carbonate selected from the group
consisting of dimethyl carbonate, ethylmethyl carbonate, diethyl
carbonate, methyl-n-propyl carbonate, ethyl-n-propyl carbonate and
di -n-propyl carbonate, in addition to the specific carbonate
mentioned before. Of these, diethyl carbonate, methyl-n-propyl
carbonate and ethyl-n-propyl carbonate are preferable, and diethyl
carbonate is particularly preferable because of its excellent cycle
characteristics when used for the non-aqueous liquid electrolyte
secondary battery.
[0223] There is no special limitation on the kind of the chained
carboxylic acid ester. Examples of those usually used include:
methyl acetate, ethyl acetate, n-propyl acetate, i-propyl acetate,
n-butyl acetate, i-butyl acetate, t-butyl acetate, methyl
propionate, ethyl propionate, n-propyl propionate, i-propyl
propionate, n-butyl propionate, i-butyl propionate and t-butyl
propionate.
[0224] Of these compounds, preferable are ethyl acetate, methyl
propionate and ethyl propionate.
[0225] There is no special limitation on the kind of cyclic
carboxylic acid ester. Examples of those usually used include:
.gamma.-butyrolactone, .gamma.-valerolactone and
.delta.-valerolactone.
[0226] Of these, .gamma.-butyrolactone is preferable.
[0227] There is no special limitation on the kind of the chained
ether. Examples of those usually used include: dimethoxymethane,
dimethoxyethane, diethoxymethane, diethoxyethane,
ethoxymethoxymethane and ethoxymethoxyethane.
[0228] Of these, dimethoxyethane and diethoxyethane are
preferable.
[0229] There is no special limitation on the kind of the cyclic
ether. Examples of those usually used include: tetrahydrofuran and
2-methyltetrahydrofuran.
[0230] There is no special limitation on the kind of the
phosphor-containing organic solvent. Examples of those usually used
include: phosphoric acid esters such as trimethyl phosphate,
triethyl phosphate and triphenyl phosphate; phosphinic acid esters
such as trimethyl phosphite, triethyl phosphite and triphenyl
phosphite; and phosphine oxides such as trimethyl phosphine oxide,
triethyl phosphine oxide and triphenylphosphine oxide.
[0231] There is no special limitation on the kind of the
sulfur-containing organic solvent. Examples of those usually used
include: ethylene sulfite, 1,3-propane sultone, 1,4-butane sultone,
methyl methane sulfonate, busulfan, sulfolane, sulforene, dimethyl
sulfone, diphenyl sulfone, methyl phenyl sulfone, dibutyl
disulfide, dicyclohexyl disulfide, tetramethyl thiuram monosulfide,
N,N-dimethylmethane sulfonamide and N,N-diethylmethane
sulfonamide.
[0232] Of these compounds, it is preferable to use ethylene
carbonate and/or propylene carbonate, which belongs to cyclic
carbonate. It is further preferable to combine the linear carbonate
with these cyclic carbonates.
[0233] When the cyclic carbonate and linear carbonate are used in
combination as non-aqueous solvent, preferable content of the
linear carbonate in the non-aqueous solvent of the first
non-aqueous liquid electrolyte of the present invention is usually
30 weight % or higher, preferably 50 eight % or higher, and usually
95 weight % or lower, preferably 90 eight % or lower. On the other
hand, preferable content of the cyclic carbonate in the non-aqueous
solvent of the first non-aqueous liquid electrolyte of the present
invention is usually 5 weight % or higher, preferably 10 weight %
or higher, and usually 50 weight % or lower, preferably 40 weight %
or lower. When the content of the linear carbonate is too low, the
viscosity of the first non-aqueous liquid electrolyte of the
present invention may increase. When the content is too high,
dissociation degree of electrolyte lithium salt becomes low,
leading to a decrease in electric conductivity of the first
non-aqueous liquid electrolyte of the present invention.
[0234] In the non-aqueous liquid electrolyte (I), the saturated
cyclic carbonate functions as non-aqueous solvent. Therefore, other
non-aqueous solvent may be added to the above specific compound (I)
and saturated cyclic carbonate but this is not necessary. When
other non-aqueous solvent is combined, the total amount of the
saturated cyclic carbonate and other non-aqueous solvent should
preferably fall within the range specified above for the
non-aqueous solvent.
[0235] [I-4. Electrolyte]
[0236] There is no special limitation on the kind of electrolyte
used for the first non-aqueous liquid electrolyte of the present
invention. Any electrolyte known to be used as electrolyte of the
intended non-aqueous liquid electrolyte secondary battery can be
used. When the first non-aqueous liquid electrolyte of the present
invention is used for the lithium secondary battery, a lithium salt
is usually used as electrolyte.
[0237] Concrete examples of electrolytes include: inorganic lithium
salts such as LiClO.sub.4, LiAsF.sub.6, LiPF.sub.6,
Li.sub.2CO.sub.3, and LiBF.sub.4; fluorine-containing organic
lithium salt such as LiCF.sub.3SO.sub.3,
LiN(CF.sub.3SO.sub.2).sub.2, LiN(C.sub.2F.sub.5SO.sub.2).sub.2,
lithium 1,3-hexafluoropropane disulfonylimide, lithium
1,2-tetrafluoroethane disulfonylimide,
LiN(CF.sub.3SO.sub.2)(C.sub.4F.sub.9SO.sub.2),
LiC(CF.sub.3SO.sub.2).sub.3, LiPF.sub.4(CF.sub.3).sub.2,
LiPF.sub.4(C.sub.2F.sub.5).sub.2,
LiPF.sub.4(CF.sub.3SO.sub.2).sub.2,
LiPF.sub.4(C.sub.2F.sub.5SO.sub.2).sub.2,
LiBF.sub.2(CF.sub.3).sub.2, LiBF.sub.2(C.sub.2F.sub.5).sub.2,
LiBF.sub.2(CF.sub.3SO.sub.2).sub.2 and
LiBF.sub.2(C.sub.2F.sub.5SO.sub.2).sub.2; dicarboxylic
acid-containing lithium salt complexes such as lithium
bis(oxalato)borate, lithium tris(oxalato)phosphate and lithium
difluorooxalatoborate; and sodium salts and potassium salts such as
KPF.sub.6, NaPF.sub.6, NaBF.sub.4 and NaCF.sub.3SO.sub.3.
[0238] Of these, preferable are LiPF.sub.6, LiBF.sub.4,
LiCF.sub.3SO.sub.3, LiN(CF.sub.3SO.sub.2).sub.2,
LiN(C.sub.2F.sub.5SO.sub.2).sub.2 and lithium 1,2-tetrafluoroethane
disulfonylimide. Particularly preferable are LiPF.sub.6 and
LiBF.sub.4.
[0239] The electrolyte can be used either singly or as a mixture of
more than one kind in any combination and in any ratio. In
particular, when two specific inorganic lithium salts are combined,
or inorganic lithium salt and fluorine-containing organic lithium
salt are combined, gas evolution at the time of trickle charging is
suppressed or deterioration at the time of high temperature storage
is suppressed, which is desirable. Particularly preferable are the
combination of LiPF.sub.6 and LiBF.sub.4, or the combination of
inorganic lithium salt, such as LiPF.sub.6 and/or LiBF.sub.4, and
fluorine-containing organic lithium salt, such as
LiCF.sub.3SO.sub.3, LiN(CF.sub.3SO.sub.2).sub.2 and
LiN(C.sub.2F.sub.5SO.sub.2).sub.2.
[0240] When LiPF.sub.6 and LiBF.sub.4 are combined, it is
preferable that the ratio of LiBF.sub.4 in the whole electrolyte is
usually 0.01 weight % or higher and 20 weight % or lower.
Dissociation of LiBF.sub.4 is not extensive and if the ratio is too
high, resistance of the liquid electrolyte may become high.
[0241] When inorganic lithium salt such as LiPF.sub.6 and
LiBF.sub.4 and fluorine-containing organic lithium salt such as
LiCF.sub.3SO.sub.3, LiN(CF.sub.3SO.sub.2).sub.2 and
LiN(C.sub.2F.sub.5SO.sub.2).sub.2 are used in combination, it is
preferable that the ratio of inorganic lithium salt in the whole
electrolyte is usually 70 weight % or higher, and 99 weight % or
lower. The molecular weight of fluorine-containing organic lithium
salt is generally higher than that of inorganic lithium salt.
Therefore, when that ratio is too high, the ratio of solvent in the
liquid electrolyte decreases, resulting in high resistance of the
liquid electrolyte.
[0242] No particular limitation is imposed on the concentration of
the lithium salt in the first non-aqueous liquid electrolyte of the
present invention, insofar as the advantage of the present
invention is not significantly impaired. It is usually 0.5
moldm.sup.-3 or higher, preferably 0.6 moldm.sup.-3 or higher, more
preferably 0.8 moldm.sup.-3 or higher, and usually 3 moldm.sup.-3
or lower, preferably 2 moldm.sup.-3 or lower, more preferably 1.5
moldm.sup.-3 or lower. When the concentration is too low, the
electric conductivity of the non-aqueous liquid electrolyte may be
inadequate. When the concentration is too high, the electric
conductivity decreases due to high viscosity, resulting in low
performance of the non-aqueous electrolyte secondary battery based
on the first non-aqueous liquid electrolyte of the present
invention.
[0243] [I-5. Additive]
[0244] It is preferable that the first non-aqueous liquid
electrolyte of present invention contains various additives to the
extent that the advantage of the present invention is not
significantly impaired. As the additive, any known ones can be
used. The additive can be used either singly or as a mixture of
more than one kind in any combination and in any ratio.
[0245] Examples of additives include overcharge-preventing agent
and auxiliary agent used to improve capacity retention
characteristics and cycle characteristics after the high
temperature storage.
[0246] Concrete examples of overcharge-preventing additives are:
aromatic compound such as biphenyl, alkyl biphenyl, terphenyl,
partially hydrogenated terphenyl, cyclohexylbenene, t-butylbenzene,
t-amylbenzene, diphenylether and dibenzofuran; partially
fluorinated above aromatic compound such as 2-fluorobiphenyl,
o-cyclohexylfluorobenzene and p-cyclohexylfluorobenzene;
fluorine-containing anisole compound such as 2,4-difluoroanisole,
2,5-difluoroanislole and 2,6-difluoroanisole.
[0247] These overcharge-preventing additives can be used either
singly or as a mixture of more than one kind in any combination and
in any ratio.
[0248] When the first non-aqueous liquid electrolyte of the present
invention contains overcharge-preventing additive, no particular
limitation is imposed on its concentration used, insofar as the
advantage of the present invention is not significantly impaired.
Its content in the non-aqueous liquid electrolyte is preferably 0.1
weight % or higher, and 5 weight % or lower. By incorporating the
overcharge-preventing additive in the non-aqueous liquid
electrolyte, it is possible to prevent rupture and ignition caused
by overcharge of the non-aqueous liquid electrolyte secondary
battery, which preferably contributes to the enhancement of safety
of the non-aqueous liquid electrolyte secondary battery.
[0249] On the other hand, concrete examples of auxiliary agent used
to improve capacity retention characteristics and cycle
characteristics after the high temperature storage are: anhydrides
of dicarboxylic acid such as succinic acid, maleic acid and
phthalic acid; carbonate compounds except those designated as
specific carbonates, such as erystan carbonate and
spiro-bis-dimethylene carbonate; sulfur-containing compounds such
as ethylene sulfite, 1,3-propane sultone, 1,4-butane sultone,
methyl methanesulfonate, busulfane, sulforane, sulforene, dimethyl
sulfone, diphenyl sulfone, methylphenyl sulfone, dibutyl disulfide,
dicyclohexyl disulfide, tetramethylthiuram monosulfide,
N,N-dimethylmethane sulfonamide and N,N-diethylmethane sulfonamide;
nitrogen-containing compounds such as 1-methyl-2-pyrolidinone,
1-methyl-2-piperidone, 3-methyl-2-oxazolidinone,
1,3-dimethly-2-imidazolidinone and N-methylsuccinimide; hydrocarbon
compounds such as heptane, octane and cycloheptane; and
fluorine-containing aromatic compounds such as fluorobenzene,
difluorobenene and benzotrifluoride.
[0250] These auxiliary agents can be used either singly or as a
mixture of more than one kind in any combination and in any
ratio.
[0251] When the first non-aqueous liquid electrolyte of the present
invention contains the auxiliary agent, no limitation is imposed on
its concentration, insofar as the advantage of the present
invention is not significantly impaired. Usually, it is preferable
that its concentration in the entire non-aqueous liquid electrolyte
is 0.1 weight % or higher and 5 weight % or lower.
[0252] [II. First Non-Aqueous Liquid Electrolyte Secondary
Battery]
[0253] Next, explanation will be given on the non-aqueous liquid
electrolyte secondary battery, based on the first non-aqueous
liquid electrolyte of the present invention (hereafter abbreviated
as "first non-aqueous liquid electrolyte secondary battery of the
present invention") mentioned above. The first non-aqueous liquid
electrolyte secondary battery of the present invention comprises a
anode electrode and a cathode electrode, capable of intercalating
and deintercalating lithium ions, and a non-aqueous liquid
electrolyte, the anode electrode containing a anode electrode
active material having at least one kind of atom selected from the
group consisting of Si atom, Sn atom and Pb atom, wherein said
non-aqueous liquid electrolyte is the first non-aqueous liquid
electrolyte of the present invention mentioned above.
[0254] [II-1. Constitution of Battery]
[0255] Constitution of the first non-aqueous liquid electrolyte
secondary battery of the present invention is similar to that of
the known non-aqueous liquid electrolyte secondary battery except
the constitution of the anode electrode and non-aqueous liquid
electrolyte. Usually, the cathode electrode and anode electrode are
layered with a porous membrane (a separator) interposed therein,
which is impregnated with the first non-aqueous liquid electrolyte
of the present invention, and the whole structure is stored in a
case (an outer package). There is no special limitation on the
shape of the first non-aqueous liquid electrolyte secondary battery
of the present invention. The shape may be cylindrical, prismatic,
laminated, coin-like or large size-type.
[0256] [II-2. Non-Aqueous Liquid Electrolyte]
[0257] As non-aqueous liquid electrolyte, the first non-aqueous
liquid electrolyte of the present invention, described above, is
used. Other non-aqueous liquid electrolyte can be added to the
first non-aqueous liquid electrolyte of the present invention to
such an extent that it does not depart from the scope of the
present invention.
[0258] [II-3. Anode Electrode]
[0259] The anode electrode of the first non-aqueous liquid
electrolyte secondary battery of the present invention comprises
anode electrode active material having at least one kind of atom
selected from the group consisting of Si atom, Sn atom and Pb atom
(hereafter referred to as "specific metal element" as
appropriate).
[0260] As examples of anode electrode active material containing at
least one element selected from the specific metal elements can be
cited: any one specific metal element alone; alloys consisting of
two or more kinds of the specific metal elements; alloys consisting
of one or more of the specific metal elements and one or more other
metal elements; and compounds containing one or more of the
specific metal elements. It is possible to realize higher capacity
of the battery by using these metal elements, alloys or metal
compounds as anode electrode active material.
[0261] As examples of compounds containing one or more of the
specific metal elements can be cited complex compounds, such as
carbide, oxide, nitride, sulfide and phosphide, containing one or
more of the specific metal elements.
[0262] Also cited are compounds in which these complex compounds
are further connected to other metal elements, alloys or several
elements such as non-metal elements in a complicated manner. More
concrete examples are alloys of Si or Sn with a metal not reacting
as anode electrode. Also usable are complex compounds containing 5
or 6 elements, in which Sn, for example, is combined with a metal
which is other than Si, Sn and Pb and is capable of acting as anode
electrode, a metal not reacting as anode electrode and a non-metal
element.
[0263] Of these anode electrode active materials, preferable are:
any one kind of the specific metal elements used alone, alloys of
two or more kinds of the specific metal elements, and oxides,
carbides or nitrides of the specific metal elements, as they have
large capacity per unit weight when made into the battery.
Particularly preferable are metal elements, alloys, oxides,
carbides and nitrides of Si and/or Sn, from the standpoint of
capacity per unit weight and small burden on the environment.
[0264] Also preferable are the following Si and/or Sn-containing
compounds because of their excellent cycle characteristics,
although they are inferior to metal alone or alloy in capacity per
unit weight.
[0265] Oxides of Si and/or Sn in which the ratio of Si and/or Sn
and oxygen is usually 0.5 to 1.5, preferably 0.7 to 1.3, more
preferably 0.9 to 1.1.
[0266] Nitrides of Si and/or Sn in which the ratio of Si and/or Sn
and nitrogen is usually 0.5 to 1.5, preferably 0.7 to 1.3, more
preferably 0.9 to 1.1.
[0267] Carbides of Si and/or Sn in which the ratio of Si and/or Sn
and carbon is usually 0.5 to 1.5, preferably 0.7 to 1.3, more
preferably 0.9 to 1.1.
[0268] The above anode electrode active material can be used either
singly or as a mixture of more than one kind in any combination and
in any ratio.
[0269] The anode electrode of the first non-aqueous liquid
electrolyte secondary battery of the present invention can be
produced according to a known method. Specifically, the anode
electrode can be produced using the above-mentioned anode electrode
active material combined with binder, electroconductor or the like,
directly by roll-molding into a sheet electrode, or by
compression-molding into a pellet electrode, for example. However,
it is usually produced by forming a thin layer containing the above
anode electrode active material (anode electrode active material
layer) on a current collector for a anode electrode (hereinafter,
referred to as "anode electrode current collector" as appropriate)
by means of coating, vapor deposition, spattering, plating or the
like. In this case, the above anode electrode active material is
mixed with, for example, binder, thickener, electroconductor,
solvent or the like to be made into the form of slurry. Then the
slurry is applied to the anode electrode current collector, dried
and pressed to increase its density, thereby the anode electrode
active material layer being formed on the anode electrode current
collector.
[0270] As materials of anode electrode current collector can be
cited steel, copper alloy, nickel, nickel alloy and stainless
steel. Of these materials, preferable is copper foil, because of
its thin-layer formability and low cost.
[0271] The thickness of the anode electrode current collector is
usually 1 .mu.m or greater, preferably 5 .mu.m or greater, and
usually 100 .mu.m or less, preferably 50 .mu.m or less. When the
anode electrode current collector is too thick, the capacity of the
entire battery may become too low. On the other hand, when it is
too thin, its handling is sometimes difficult.
[0272] In order to increase the bindability of the anode electrode
current collector to the anode electrode active material layer
formed thereon, it is preferable that the surface of the anode
electrode current collector is subjected to roughening procedure in
advance. Examples of surface roughening methods include: blasting
procedure; rolling with a rough-surfaced roll; mechanical polishing
in which the collector surface is polished with such means as an
abrasive cloth or abrasive paper onto which abradant particles are
adhered, a whetstone, an emery buff and a wire brush equipped with
steel wire; electropolishing; and chemical polishing.
[0273] In order to decrease the weight of the anode electrode
current collector and increase energy density of the battery per
unit weight, it is also possible to use a perforated-type anode
electrode current collectors such as an expanded metal or a
punching metal. This type of anode electrode current collector is
freely adjustable in its weight by means of adjusting its ratio of
perforation. Besides, when the anode electrode active material
layer is formed on both sides of this perforated-type of anode
electrode current collector, the anode electrode active material
layer is riveted at these perforations and becomes resistant to
exfoliation of the anode electrode active material layer. However,
if the ratio of perforation is too high, bond strength may rather
decrease because the contact area between the anode electrode
active material layer and the anode electrode current collector
becomes too small.
[0274] Slurry for making the anode electrode active material layer
is usually prepared by adding such agents as binder and thickener
to the anode electrode material. Incidentally, in this
specification, the term "anode electrode material" indicates a
material containing both anode electrode active material and
electroconductor.
[0275] The content of the anode electrode active material in the
anode electrode material is usually 70 weight % or higher,
preferably 75 weight % or higher, and usually 97 weight % or lower,
preferably 95 weight % or lower. When the content of the anode
electrode active material is too low, the capacity of the secondary
battery based on the anode electrode obtained tends to be
insufficient. When the content is too high, the relative content of
the binder etc. becomes low, leading to insufficient strength of
the anode electrode. When two or more kinds of anode electrode
active materials are combined, the sum of the materials should fall
within the above range.
[0276] As electroconductor to be used for the anode electrode can
be cited metal material such as copper and nickel, and carbon
materials such as graphite and carbon black. These materials can be
used either singly or as a mixture of more than one kind in any
combination and in any ratio. Carbon material can be advantageously
used as electroconductor, as this material can also function as
active material. The content of the electroconductor in the anode
electrode material is usually 3 weight % or higher, preferably 5
weight % or higher, and usually 30 weight % or lower, preferably 25
weight % or lower. When the content of the electroconductor is too
low, conductivity may be inadequate. When it is too high, the
relative content of the anode electrode active material may be
inadequate, leading to a decrease in battery capacity and
mechanical strength. When two or more electroconductors are
combined, the total content of the electroconductors should be
adjusted to fall within the above range.
[0277] As binder to be used for the anode electrode, any such
material can be used insofar as it is stable in a solvent used for
electrode production and in a liquid electrolyte. As examples can
be cited polyfluorinated vinylidene, polytetrafluoro ethylene,
polyethylene, polypropylene, styrene butadiene rubber, isoprene
rubber, butadiene rubber, ethylene acrylic acid copolymer and
ethylene metacrylic acid copolymer. These binders can be used
either singly or as a mixture of more than one kind in any
combination and in any ratio. The content of the binder per 100
weight parts of the anode electrode material is usually 0.5 weight
part or more, preferably 1 weight part or more, and usually 10
weight parts or less, preferably 8 weight parts or less. When the
content of the binder is too small, mechanical strength of the
anode electrode obtained tends to be insufficient. When the content
is too high, the relative content of the anode electrode active
material is low, leading possibly to insufficient battery capacity
and conductivity. When two or more binders are combined, the total
content of the binders should be adjusted to fall within the above
range.
[0278] As thickener to be used for the anode electrode can be cited
carboxymethyl cellulose, methyl cellulose, hydroxymethyl cellulose,
ethyl cellulose, polyvinyl alcohol, oxidized starch, phosphorylated
starch and casein. These may be used either singly or as a mixture
of more than one kind in any combination and in any ratio. The
thickener may be used when considered necessary. When it is used,
it is preferable that its content in the anode electrode active
material is usually held at 0.5 weight % or higher, and 5 weight %
or lower.
[0279] Slurry for making the anode electrode active material layer
is usually prepared by mixing, as needed, electroconductor, binder
or thickener with the above anode electrode active material, using
aqueous solvent or organic solvent as dispersion medium. As aqueous
solvent, water is usually used. It is also possible to mix other
solvent, e.g. alcohol such as ethanol or cyclic amide such as
N-methylpyrrolidone, in a ratio not exceeding about 30 weight %
relative to water. Examples of organic solvent usually used
include: cyclic amides such as N-methylpyrrolidone; straight chain
amides such as N,N-dimethylformamide and N,N-dimethylacetamide;
aromatic hydrocarbons such as anisole, toluene and xylene; and
alcohols such as butanol and cyclohexanol. Of these, preferable are
cyclic amides, such as N-methylpyrrolidone, and straight chain
amides, such as N,N-dimethylformamide and N,N-dimethylacetamide.
These solvents can be used either singly or as a mixture of more
than one kind in any combination and in any ratio.
[0280] No particular limitation is imposed on the viscosity of the
slurry, insofar as the slurry can be applied on the current
collector. The amount of the solvent used at the time of slurry
preparation can be adjusted appropriately to give a suitable
viscosity for application.
[0281] Slurry obtained is applied on the above anode electrode
current collector, and after drying and pressing, anode electrode
active material layer is formed. No particular limitation is
imposed on the method of application and known methods can be used.
No particular limitation is imposed on the method of drying either,
and per se known methods such as air drying, heated-air drying and
reduced-pressure drying can be used.
[0282] There is no special limitation on the electrode structure
when anode electrode active material is made into an electrode by
the above-mentioned method. The density of the active material on
the current collector is preferably 1 gcm.sup.-3 or higher, more
preferably 1.2 gcm.sup.-3 or higher, still more preferably 1.3
gcm.sup.-3 or higher, and usually 2 gcm.sup.-3 or lower, preferably
1.9 gcm.sup.-3 or lower, more preferably 1.8 gcm.sup.-3 or lower,
still more preferably 1.7 gcm.sup.-3 or lower. When the density
exceeds the above-mentioned upper limit, active material particles
are destroyed and an increase in initial irreversible capacity and
deterioration in charge-discharge characteristic under high current
densities, caused by decrease in immersibility of the non-aqueous
liquid electrolyte near the interface of the current
collector/active material, may result. When the density is below
the above range, conductivity in the active material may be poor,
battery resistance may increase and capacity per unit volume may be
low.
[0283] [II-4. Cathode Electrode]
[0284] The cathode electrode of the first non-aqueous liquid
electrolyte secondary battery of the present invention contains
cathode electrode active material, similarly to a usual non-aqueous
liquid electrolyte secondary battery.
[0285] Examples of cathode electrode active material include
inorganic compounds such as transition metal oxides, composite
oxides of transition metal and lithium (lithium transition metal
composite oxide), transition metal sulfides and metal oxides, and
metal lithium, lithium alloys and their composites. Concrete
examples are: transition metal oxides such as MnO, V.sub.2O.sub.5,
V.sub.6O.sub.13 and TiO.sub.2; lithium transition metal composite
oxides such as LiCoO.sub.2 or lithium cobalt composite oxide whose
basic composition is LiCoO.sub.2, LiNiO.sub.2 or lithium nickel
composite oxide whose basic composition is LiNiO.sub.2,
LiMn.sub.2O.sub.4 or LiMnO.sub.2 or lithium manganese composite
oxide whose basic composition is LiMn.sub.2O.sub.4 or LiMnO.sub.2,
lithium nickel manganese cobalt composite oxide and lithium nickel
cobalt aluminum composite oxide; transition metal sulfides such as
TiS and FeS and metal oxides such as SnO.sub.2 and SiO.sub.2. Of
these compounds, preferable are lithium transition metal composite
oxides, more concretely LiCoO.sub.2 or lithium cobalt composite
oxide whose basic composition is LiCoO.sub.2, LiNiO.sub.2 or
lithium nickel composite oxide whose basic composition is
LiNiO.sub.2, LiMn.sub.2O.sub.4 or LiMnO.sub.2 or lithium manganese
composite oxide whose basic composition is LiMn.sub.2O.sub.4 or
LiMnO.sub.2, lithium nickel manganese cobalt composite oxide and
lithium nickel cobalt aluminum composite oxide, because they can
provide both high capacity and excellent cycle characteristics.
Lithium transition metal composite oxides are preferable also
because their chemical stability can be improved by replacing a
part of cobalt, nickel or manganese in the lithium transition metal
composite oxide with other metals such as Al, Ti, V, Cr, Mn, Fe,
Co, Li, Ni, Cu, Zn, Mg, Ga or Zr, because. These cathode electrode
active materials can be used either singly or as a mixture of more
than one material in any combination and in any ratio.
[0286] The cathode electrode of the first non-aqueous liquid
electrolyte secondary battery of the present invention can be
produced according to a known method. Concretely, for example, the
cathode electrode can be produced using the above-mentioned cathode
electrode active material combined with binder, electroconductor or
the like, directly by roll-molding into a sheet electrode, by
compression-molding into a pellet electrode, by means of forming a
cathode electrode active material layer applying the active
material on a current collector for a cathode electrode
(hereinafter, referred to as "cathode electrode current collector"
as appropriate) (coating method), or by means of forming a thin
layer (cathode electrode active material layer) containing the
above cathode electrode active material on a current collector by
vapor deposition, spattering, plating or the like. Usually, it is
produced by the coating method.
[0287] When by the coating method, the above cathode electrode
active material is mixed with, for example, binder, thickener,
electroconductor, solvent or the like to be made into the form of
slurry. Then the slurry is applied to the cathode electrode current
collector, dried and pressed to increase its density, thereby the
cathode electrode active material layer being formed on the cathode
electrode current collector.
[0288] As materials of cathode electrode current collector can be
cited aluminum, titanium, tantalum and alloy containing one or more
of these metals. Of these, aluminum and its alloy are
preferable.
[0289] The thickness of the cathode electrode current collector is
usually 1 .mu.m or greater, preferably 5 .mu.m or greater, and
usually 100 .mu.m or less, preferably 50 .mu.m or less. When the
cathode electrode current collector is too thick, the capacity of
the entire battery may become too low. On the other hand, when it
is too thin, its handling is sometimes difficult.
[0290] In order to increase the bindability of the cathode
electrode current collector to the cathode electrode active
material layer formed thereon, it is preferable that the surface of
the cathode electrode current collector is subjected to roughening
procedure in advance. Examples of surface roughening methods
include: blasting procedure; rolling with a rough-surfaced roll;
mechanical polishing in which the collector surface is polished
with such means as an abrasive cloth or abrasive paper onto which
abradant particles are adhered, a whetstone, an emery buff and a
wire brush equipped with steel wire; electropolishing; and chemical
polishing.
[0291] In order to decrease the weight of the cathode electrode
current collector and increase energy density of the battery per
unit weight, it is also possible to use a perforated-type cathode
electrode current collectors such as an expanded metal or a
punching metal. This type of cathode electrode current collector is
freely adjustable in its weight by means of adjusting its ratio of
perforation. Besides, when the cathode electrode active material
layer is formed on both sides of this perforated-type of cathode
electrode current collector, the cathode electrode active material
layer is riveted at these perforations and becomes resistant to
exfoliation of the cathode electrode active material layer.
However, if the ratio of perforation is too high, bond strength may
rather decrease because the contact area between the cathode
electrode active material layer and the cathode electrode current
collector becomes too small.
[0292] Usually, electroconductor is included in the cathode
electrode active material layer in order to increase conductivity.
There is no special limitation on the kind of electroconductor
used. Concrete examples are metallic materials, such as copper and
nickel, and carbonaceous material, e.g. graphite such as natural
graphite and artificial graphite, carbon black such as acetylene
black and amorphous carbon like needle coke. These materials can be
used either singly or as a mixture of more than one kind in any
combination and in any ratio.
[0293] The content of electroconductor in the cathode electrode
active material layer is usually 0.01 weight % or higher,
preferably 0.1 weight % or higher, more preferably 1 weight % or
higher, and usually 50 weight % or lower, preferably 30 weight % or
lower, more preferably 15 weight % or lower. When the content is
too low, conductivity may be inadequate. When it is too high,
capacity of the battery may decrease.
[0294] As binder to be used for the preparation of the cathode
electrode active material layer, any such material can be used in
the case of coating insofar as it is stable in a liquid medium used
at the time of electrode preparation. Concrete examples are: resin
polymers such as polyethylene, polypropylene, polyethylene
terephthalate, polymethyl metacrylate, aromatic polyamide,
cellulose and nitrocellulose; rubber-type polymers such as SBR
(styrene butadiene rubber), NBR (acrylonitrile butadiene rubber),
fluorinated rubber, isoprene rubber, butadiene rubber and ethylene
propylene rubber; thermoplastic elastomer-type polymers such as
styrene-butadiene-styrene block copolymer and its hydrogenated
products, EPDM (ethylene-propylene-diene terpolymer), styrene
ethylene butadiene ethylene copolymer, styrene isoprene styrene
block copolymer and its hydrogenated product; soft resin polymers
such as syndiotactic-1,2-polybutadiene, polyvinyl acetate, ethylene
vinyl acetate copolymer and propylene .alpha.-olefin copolymer;
fluorinated polymers such as polyfluorinated vinylidene,
polytetrafluoroethylene, fluorinated polyfluorovinylidene and
polytetrafluoroethylene ethylene copolymer; and high molecular
composite materials having ionic conductivity for alkali metal ion
(especially lithium ion). These materials can be used either singly
or as a mixture of more than one material in any combination and in
any ratio.
[0295] The content of the binder in the cathode electrode active
material layer is usually 0.1 weight % or higher, preferably 1
weight % or higher, more preferably 5 weight % or higher, and
usually 80 weight % or lower, preferably 60 weight % or lower, more
preferably 40 weight % or lower, most preferably 10 weight % or
lower. When the content of the binder is too low, the cathode
electrode active material can not be adequately retained and
mechanical strength of the cathode electrode may decrease, leading
to deterioration of battery characteristics such as cycle
characteristics. When the content is too high, battery capacity and
conductivity may deteriorate.
[0296] As liquid medium for making slurry, any solvent can be used
insofar as it can dissolve or disperse cathode electrode active
material, electroconductor, binder and, as needed, thickener.
Either aqueous solvent or organic solvent can be used.
[0297] Examples of aqueous solvent include water, and mixture of
water and alcohol. Examples of organic solvent include: aliphatic
hydrocarbons such as hexane; aromatic hydrocarbons such as benzene,
toluene, xylene and methylnaphthalene; heteroaromatic compounds
such as quinoline and pyridine; ketones such as acetone,
methylethyl ketone and cyclohexanone; esters such as methyl acetate
and methyl acrylate; amines such as diethylene triamine and
N,N-dimethylaminopropylamine; ethers such as diethyl ether,
propylene oxide and tetrahydrofuran (THF); amides such as
N-methylpyrrolidone (NMP), dimethylformamide and dimethylacetamide;
and non-protonic polar solvents such as hexamethylphosphoramide and
dimethylsulfoxide.
[0298] Especially when an aqueous solvent is used, it is preferable
to prepare the slurry using a thickener and latex such as styrene
butadiene rubber (SBR). A thickener is usually used to adjust the
viscosity of slurry. There is no limitation on the kind of
thickener. As concrete examples can be cited carboxymethyl
cellulose, methyl cellulose, hydroxymethyl cellulose, ethyl
cellulose, polyvinyl alcohol, oxidized starch, phosphorylated
starch, casein, and salts of these compounds. These compounds can
be used either singly or as a mixture of more than one compound in
any combination and in any ratio. When a thickener is used, the
proportion of the thickener in the active material is usually 0.1
weight % or higher, preferably 0.5 weight % or higher, more
preferably 0.6 weight % or higher, and usually 5 weight % or lower,
preferably 3 weight % or lower, more preferably 2 weight % or
lower. When the proportion is below the above range, coatability
may be extremely low. When the proportion exceeds the above range,
the ratio of the active material in the cathode electrode active
material layer decreases and there is a possibility that battery
capacity becomes low and resistance in the cathode electrode active
materials become large.
[0299] No particular limitation is imposed on the viscosity of the
slurry, insofar as the slurry can be applied on the current
collector. The amount of the solvent used at the time of slurry
preparation can be adjusted appropriately to give a suitable
viscosity for application.
[0300] Slurry obtained is applied on the above cathode electrode
collector, and after drying and pressing anode electrode active
material layer is formed. No particular limitation is imposed on
the method of application and known methods can be used. No
particular limitation is imposed on the method of drying either,
and per se known methods such as air drying, heated-air drying and
reduced-pressure drying can be used.
[0301] It is preferable that the cathode electrode active material
layer obtained through processes such as coating and drying is
subjected to consolidation process by such means as hand pressing
or roller pressing in order to increase packing density of the
cathode electrode active material.
[0302] The density of the cathode electrode active material is
preferably 1.5 gcm.sup.-3 or higher, more preferably 2 gcm.sup.-3
or higher, still more preferably 2.2 gcm.sup.-3 or higher, and
preferably 3.5 gcm.sup.-3 or lower, more preferably 3 gcm.sup.-3 or
lower, still more preferably 2.8 gcm.sup.-3 or lower. When the
density exceeds the above-mentioned upper limit, a decrease in
immersibility of the non-aqueous liquid electrolyte near the
interface of the current collector/active material may occur and
deterioration in charge-discharge characteristic under high current
densities may result. When the density is below the above range,
conductivity in the active material may be poor and battery
resistance may increase.
[0303] [II-5. Separator]
[0304] Usually, a separator is installed between the cathode
electrode and the anode electrode to prevent shortings. In the
case, the first non-aqueous liquid electrolyte of the present
invention is usually used in such a way that the separator is
impregnated with this liquid electrolyte.
[0305] There is no special limitation on the material or shape of
the separator insofar as the advantage of the present invention is
not significantly impaired. Any known ones can be used. It is
particularly preferable to use porous sheet or nonwoven fabric,
with good water-retaining characteristics, which is made of
material stable in the non-aqueous liquid electrolyte of the
present invention.
[0306] As materials of the separator can be used: polyolefin such
as polyethylene and polypropylene, polytetrafluoroethylene,
polyether sulfone and glass filter. Of these materials, preferably
are glass filter and polyolefin. Particularly preferable is
polyolefin. These materials can be used either singly or as a
mixture of more than one kind in any combination and in any
ratio.
[0307] No particular limitation is imposed on the thickness of the
separator. It is usually 1 .mu.m or greater, preferably 5 .mu.m or
greater, more preferably 10 .mu.m or greater, and usually 50 .mu.m
or less, preferably 40 .mu.m or less, more preferably 30 .mu.m or
less. When the separator is too thin, insulation property and
mechanical strength may deteriorate. When it is too thick, battery
characteristics such as rate characteristics may deteriorate and
also energy density of the entire non-aqueous liquid electrolyte
secondary battery may decline.
[0308] When porous material such as porous sheet or nonwoven fabric
is used as separator, there is no special limitation on the
porosity of the separator. It is usually 20% or larger, preferably
35% or larger, more preferably 45% or larger, and usually 90% or
smaller, preferably 85% or smaller, more preferably 75% or smaller.
When the porosity is too small, membrane resistance may become
large and rate characteristics may deteriorate. When it is too
large, mechanical strength of the separator may decrease, leading
to poor insulation property.
[0309] No particular limitation is imposed on the average pore
diameter of the separator. Usually, it is 0.5 .mu.m or smaller,
preferably 0.2 .mu.m or smaller, and usually 0.05 .mu.m or larger.
When the average pore diameter is too large, shortings are liable
to occur. When it is too small, membrane resistance may become
large and rate characteristics may deteriorate.
[0310] [II-6. Outer Package]
[0311] The first non-aqueous liquid electrolyte secondary battery
of the present invention is usually constituted by storing the
above non-aqueous liquid electrolyte, anode electrode, cathode
electrode and separator or the like in an outer package. There is
no special limitation on this outer package and any known one can
be used insofar as the advantageous effect of the present invention
is not significantly impaired.
[0312] Concretely, there is no special limitation on the material
of the outer package. Usually, nickel-plated iron, stainless steel,
aluminum and its alloys, nickel and titanium are used.
[0313] There is no limitation on the shape of the outer package,
either. The shape may be cylindrical, prismatic, laminated,
coin-like or large size.
[0314] [III. Others]
[0315] [III-1. Second Non-Aqueous Liquid Electrolyte and
Non-Aqueous Liquid Electrolyte Secondary Battery]
[0316] The above-mentioned component (i) (specific compound (I) and
the saturated cyclic carbonate) may improve charge-discharge cycle
characteristics of the non-aqueous liquid electrolyte secondary
battery even when specific carbonate is not combined in the
non-aqueous liquid electrolyte. In the following, explanation will
be given on the non-aqueous liquid electrolyte which contains
component (i) (specific compound (I) and the saturated cyclic
carbonate) and does not require the specific carbonate (non-aqueous
liquid electrolyte related to the second subject of the present
invention. Hereafter abbreviated as "second non-aqueous liquid
electrolyte" as appropriate) and the non-aqueous liquid electrolyte
secondary battery based on it (abbreviated as "second non-aqueous
liquid electrolyte secondary battery of the present invention" as
appropriate).
[0317] The second non-aqueous liquid electrolyte of the present
invention is a non-aqueous liquid electrolyte to be used for a
non-aqueous liquid electrolyte secondary battery comprising a anode
electrode and a cathode electrode, capable of intercalating and
deintercalating lithium ions, and a non-aqueous liquid electrolyte,
the anode electrode containing a anode electrode active material
having at least one kind of atom selected from the group consisting
of Si atom, Sn atom and Pb atom (specific metal element).
[0318] The second non-aqueous liquid electrolyte is characterized
in that it contains the above-mentioned component (i), namely the
above-mentioned specific compound (I) and saturated cyclic
carbonate. The details of the specific compound (I) and saturated
cyclic carbonate are similar to what has been described in
<I-1-1. Component (i)>. The ratio of specific compound (I)
and the saturated cyclic carbonate in the second non-aqueous liquid
electrolyte is also similar to the ratio of specific compound (I)
and the saturated cyclic carbonate in the non-aqueous liquid
electrolyte (I) described in <I-1-1. Component (i)>.
[0319] The details (requirement, kind, ratio etc.) of components
other than specific compound (I) and the saturated cyclic carbonate
(non-aqueous solvent, electrolyte, additive etc.) of the second
non-aqueous liquid electrolyte are similar to what has been
described in each item ([I-3. Non-aqueous solvent], [I-4.
Electrolyte], [I-5. Additive]) for the above-mentioned [I. First
non-aqueous liquid electrolyte].
[0320] The use of the second non-aqueous liquid electrolyte may
improve charge-discharge cycle characteristics of the non-aqueous
liquid electrolyte secondary battery based on the anode electrode
active material containing the above-mentioned specific metal
element, even though it does not contain the specific carbonate, as
described above. The detailed reason is not clear but inferred as
follows.
[0321] Namely, chemical reactivity of specific compound (I) of the
second non-aqueous liquid electrolyte towards anode electrode
active material containing the above specific metal element is held
low by the presence of alkyl group or fluoroalkyl group with 3 or
more carbon atoms. Side reactions are thus suppressed and cycle
deterioration is evaded. Similar effect is obtained when the total
number of carbon atoms of alkyl or fluoroalkyl groups of specific
compound (I) is 5 or more. And the solubility of the electrolytes
becomes higher by the presence of saturated cyclic carbonate
combined with specific compound (I), leading to improvement in
charge-discharge cycle characteristics.
[0322] The details of the non-aqueous liquid electrolyte secondary
battery based on the second non-aqueous liquid electrolyte (second
non-aqueous liquid electrolyte secondary battery), except those for
the non-aqueous liquid electrolyte, are similar to what has been
described in each item ([II-1. Constitution of battery], [II-3.
Anode electrode], [II-4. Cathode electrode], [II-5. Separator],
[II-6. Outer package]) for the above-mentioned [II. First
non-aqueous liquid electrolyte secondary battery].
[0323] The advantageous effect, however, is more pronounced when
the specific carbonate is present in the non-aqueous liquid
electrolyte in addition to specific compound (I) and saturated
cyclic carbonate (namely, the above-mentioned first non-aqueous
liquid electrolyte (I)) in comparison with the non-aqueous liquid
electrolyte without specific carbonate (namely, second non-aqueous
liquid electrolyte). As described previously, it is inferred that,
when the specific carbonate is combined with specific compound (I)
and saturated cyclic carbonate, a protective layer is formed on the
surface of the anode electrode active material and side reaction is
suppressed also, leading to improvement in property of the
protective layer.
[0324] [III-2. Third Non-Aqueous Liquid Electrolyte and Non-Aqueous
Liquid Electrolyte Secondary Battery]
[0325] The above-mentioned specific compound (II) may improve
charge-discharge cycle characteristics of the non-aqueous liquid
electrolyte secondary battery when it is included in the
non-aqueous liquid electrolyte singly and the specific carbonate is
not combined. In the following, explanation will be given on the
non-aqueous liquid electrolyte which contains specific compound
(II) and does not require the specific carbonate (non-aqueous
liquid electrolyte related to the third subject of the present
invention. Hereafter abbreviated as "third non-aqueous liquid
electrolyte" as appropriate) and the non-aqueous liquid electrolyte
secondary battery based on it (abbreviated as "third non-aqueous
liquid electrolyte secondary battery of the present invention" as
appropriate).
[0326] The third non-aqueous liquid electrolyte of the present
invention is a non-aqueous liquid electrolyte to be used for a
non-aqueous liquid electrolyte secondary battery comprising a anode
electrode and a cathode electrode, capable of intercalating and
deintercalating lithium ions, and a non-aqueous liquid electrolyte,
the anode electrode containing a anode electrode active material
having at least one kind of atom selected from the group consisting
of Si atom, Sn atom and Pb atom (specific metal element).
[0327] The third non-aqueous liquid electrolyte is characterized in
that it contains the above-mentioned specific compound (II). The
details of the specific compound (II) are similar to what has been
described in <I-1-2. Component (ii)>. The ratio of specific
compound (II) in the third non-aqueous liquid electrolyte is also
similar to the ratio of specific compound (II) in the non-aqueous
liquid electrolyte (II) described in <I-1-2. Component
(ii)>.
[0328] The details (requirement, kind, ratio etc.) of components
other than specific compound (II) (non-aqueous solvent,
electrolyte, additive etc.) of the third non-aqueous liquid
electrolyte are similar to what has been described in each item
([I-3. Non-aqueous solvent], [I-4. Electrolyte], [I-5. Additive])
for the above-mentioned [I. First non-aqueous liquid
electrolyte].
[0329] The use of the third non-aqueous liquid electrolyte makes it
possible to improve charge-discharge cycle characteristics of the
non-aqueous liquid electrolyte secondary battery based on the anode
electrode active material containing the above-mentioned specific
metal element, even though it does not contain the specific
carbonate, as described above. The detailed reason is not clear but
inferred that the specific compound (II) forms an efficient
protective layer on the surface of the anode electrode active
material, thereby suppressing side reactions and inhibiting cycle
deterioration.
[0330] The details of the non-aqueous liquid electrolyte secondary
battery based on the third non-aqueous liquid electrolyte (third
non-aqueous liquid electrolyte secondary battery), except those for
the non-aqueous liquid electrolyte, are similar to what has been
described in each item ([II-1. Constitution of battery], [II-3.
Anode electrode], [II-4. Cathode electrode], [II-5. Separator],
[II-6. Outer package]) for the above-mentioned [II. First
non-aqueous liquid electrolyte secondary battery].
[0331] The advantageous effect, however, is more pronounced when
the specific carbonate is present in the non-aqueous liquid
electrolyte in addition to specific compound (II) (namely, the
above-mentioned first non-aqueous liquid electrolyte (II)) in
comparison with the non-aqueous liquid electrolyte without specific
carbonate (namely, third non-aqueous liquid electrolyte). As
described previously, it is inferred that, when the specific
carbonate is combined with specific compound (II), a protective
layer is formed on the surface of the anode electrode active
material and side reaction is suppressed also, leading to
improvement in property of the protective layer.
[0332] [III-3. Fourth Non-Aqueous Liquid Electrolyte and
Non-Aqueous Liquid Electrolyte Secondary Battery]
[0333] The non-aqueous liquid electrolyte containing both
above-mentioned specific compound (III) and the specific carbonate
may improve charge-discharge cycle characteristics not only in
non-aqueous liquid electrolyte secondary battery based on anode
electrode active material having at least one kind of atom selected
from the group consisting of Si atom, Sn atom and Pb atom (specific
metal element), but also in non-aqueous liquid electrolyte
secondary battery based on other anode electrode active material
(non-aqueous liquid electrolyte based on graphite material etc.).
In the following, explanation will be given on the non-aqueous
liquid electrolyte which has no limitation on the kind of anode
electrode active material (non-aqueous liquid electrolyte related
to the fourth subject of the present invention. Hereafter
abbreviated as "fourth non-aqueous liquid electrolyte" as
appropriate), and the non-aqueous liquid electrolyte secondary
battery based on that non-aqueous liquid electrolyte (hereafter
referred to as "fourth non-aqueous liquid electrolyte secondary
battery of the present invention" as appropriate).
[0334] The fourth non-aqueous liquid electrolyte of the present
invention is a non-aqueous liquid electrolyte to be used for a
non-aqueous liquid electrolyte secondary battery comprising a anode
electrode and a cathode electrode, capable of intercalating and
deintercalating lithium ions, and a non-aqueous liquid electrolyte.
It is characterized in that it contains the above-mentioned
specific compound (III) and specific carbonate.
[0335] The details of the specific compound (III) and specific
carbonate are similar to what has been described in <I-1-3.
Component (iii)> and [I-2. Specific carbonate]. The proportion
of the specific compound (III) and specific carbonate in the fourth
non-aqueous liquid electrolyte is also similar to the proportion of
the specific compound (III) and specific carbonate in the
non-aqueous liquid electrolyte (III) described in <I-1-3.
Component (iii)> and [I-2. Specific carbonate].
[0336] The details (requirement, kind, ratio etc.) of components
other than specific compound (III) and specific carbonate
(non-aqueous solvent, electrolyte, additive etc.) of the fourth
non-aqueous liquid electrolyte are similar to what has been
described in each item ([I-3. Non-aqueous solvent], [I-4.
Electrolyte], [I-5. Additive]) for the above-mentioned [I. First
non-aqueous liquid electrolyte].
[0337] The non-aqueous liquid electrolyte secondary battery based
on the fourth non-aqueous liquid electrolyte (fourth non-aqueous
liquid electrolyte secondary battery) differs from the
above-mentioned first non-aqueous liquid electrolyte secondary
battery in that there is no limitation on the kind of anode
electrode active material that can be used. In the following,
explanation will be given on the anode electrode active material
that can be used for the fourth non-aqueous liquid electrolyte
secondary battery.
[0338] No particular limitation is imposed on the anode electrode
active material. Examples include carbonaceous materials, metal
materials, metal lithium and lithium alloys, which are capable of
intercalating and deintercalating lithium. Further, the anode
electrode active materials can be used either singly or as a
mixture of more than one kind in any combination and in any
ratio.
[0339] Of these, preferable are carbonaceous materials, alloys
consisting of lithium and more than one kind of metal capable of
intercalating and deintercalating lithium, and composite compound
materials such as borides, oxides, nitrides, sulfides and
phosphides of these metals.
[0340] Any carbonaceous material can be used as anode electrode
active material. Preferable are graphite, and graphite whose
surface is covered with carbon which is more amorphous than
graphite.
[0341] For the above-mentioned graphite, it is preferable that the
d value (interlayer distance) of the lattice plane (002 plane),
obtained by X ray diffraction according to the Gakushin method, is
usually 0.335 nm or larger, and usually 0.338 nm or smaller,
preferably 0.337 nm or smaller.
[0342] Furthermore, it is preferable for the graphite that its
crystallite size (Lc), obtained by X ray diffraction according to
the Gakushin method, is usually 30 nm or larger, more preferably 50
nm or larger, still more preferably 100 nm or larger.
[0343] The ash content of the graphite is usually 1 weight % or
less, preferably 0.5 weight % or less, more preferably 0.1 weight %
or less.
[0344] When the surface of the graphite is covered with amorphous
carbon, it is preferable to use as nucleus material graphite whose
d value of the lattice plane (002 plane), obtained by X ray
diffraction, is usually 0.335 nm to 0.338 nm, and to use as
covering material carbonaceous material whose d value of the
lattice plane (002 plane), obtained by X ray diffraction, is larger
than that of the nucleus material. Furthermore, it is preferable
that the weight ratio of the nucleus material and the covering
material whose d value of the lattice plane (002 plane), obtained
by X ray diffraction, is larger than that of the nucleus material
is usually in the range of 99/1 to 80/20. The use of this material
makes possible the production of anode electrode with high capacity
and low reactivity towards the non-aqueous liquid electrolyte.
[0345] There is no special limitation on the particle diameter of
the carbonaceous material, insofar as the advantage of the present
invention is not significantly impaired. The median diameter,
measured by the laser diffraction-scattering method is usually 1
.mu.m or larger, preferably 3 .mu.m or larger, more preferably 5
.mu.m or larger, still more preferably 7 .mu.m or larger. On the
other hand, its upper limit is usually 100 .mu.m or smaller,
preferably 50 .mu.m or smaller, more preferably 40 .mu.m or
smaller, still more preferably 30 .mu.m or smaller. When the
diameter is below the lower limit of the above range, the specific
surface area may be too large. When it exceeds the upper limit
thereof, the specific surface area may be too small.
[0346] There is no special limitation on the specific surface area
of the carbonaceous material, either, as measured by the BET
method, insofar as the advantage of the present invention is not
significantly impaired. It is usually 0.3 m.sup.2/g or larger,
preferably 0.5 m.sup.2/g or larger, more preferably 0.7 m.sup.2/g
or larger, still more preferably 0.8 m.sup.2/g or larger. On the
other hand, its upper limit is usually 25.0 m.sup.2/g or smaller,
preferably 20.0 m.sup.2/g or smaller, more preferably 15.0
m.sup.2/g or smaller, still more preferably 10.0 m.sup.2/g or
smaller. When the value is below the lower limit of the above
range, a sufficiently large area necessary for the insertion and
release of lithium ions can not be secured. When the upper limit is
exceeded, reactivity of the liquid electrolyte may be too high.
[0347] It is preferable that when the carbonaceous material is
examined in accordance with Raman spectroscopy employing argon ion
laser light, the R value (=I.sub.B/I.sub.A), represented by the
ratio between the peak strength I.sub.A of peak spectrum P.sub.A,
existing in the range of 1570 cm.sup.-1 to 1620 cm.sup.-1, and the
peak strength I.sub.B of peak spectrum P.sub.B, existing in the
range of 1300 cm.sup.-1 to 1400 cm.sup.-1, of the carbonaceous
material is in the range of usually 0.01 or larger and 0.7 or
smaller, from the standpoint of realizing effective battery
characteristics.
[0348] In this connection, it is preferable for good battery
characteristics that, when carbonaceous material is subjected to
Raman spectrum analysis using argon ion laser light, the
half-height width of the peak appearing in the range of 1570
cm.sup.-1 to 1620 cm.sup.-1 is usually 26 cm.sup.-1 or less, more
preferably 25 cm.sup.-1 or less
[0349] When alloy consisting of lithium and one or more kind of
metal capable of intercalating and deintercalating lithium, or
composite compound material such as boride, oxide, nitride, sulfide
or phosphide of these metals is used as anode electrode active
material, it is possible to use, as the alloy or composite compound
material, alloy containing more than one metal element or, further,
its composite compound material. For example, it is also possible
to use materials in which metal alloys or boride, oxide, nitride,
sulfide or phosphide of these alloys are chemically bonded in a
complex manner.
[0350] Of the anode electrode active materials consisting of the
above alloy or composite compound material, preferable are those
containing Si, Sn or Pb, and particularly preferable are those
containing Si or Sn, from the standpoint of large capacity per unit
weight of the anode electrode when made into a non-aqueous liquid
electrolyte secondary battery.
[0351] The proportion of the anode electrode active material and
the details of the anode electrode of the fourth non-aqueous liquid
electrolyte secondary battery, except those of the anode electrode
active material, are similar to what has been described in [II-3.
Anode electrode] of the above-mentioned [II. First non-aqueous
liquid electrolyte secondary battery].
[0352] The details of the fourth non-aqueous liquid electrolyte
secondary battery, except those for the non-aqueous liquid
electrolyte and the anode electrode, are similar to what has been
described in each item ([II-1. Constitution of battery], [II-4.
Cathode electrode], [II-5. Separator], [II-6. Outer packaging]) of
the above-mentioned [II. First non-aqueous liquid electrolyte
secondary battery].
[0353] As described above, the fourth non-aqueous liquid
electrolyte can bring about improvement in charge-discharge cycle
characteristics of not only the non-aqueous liquid electrolyte
secondary battery based on anode electrode active material
containing specific metal element, but also the battery based on
various anode electrode active material. Although detailed reason
is not clear, it is inferred that, similarly to what has been
described for the first non-aqueous liquid electrolyte (non-aqueous
liquid electrolyte (III)), an effective protective layer is formed
on the surface of the anode electrode active material by the
reactivity of both specific compound (III) and specific carbonate
contained in the non-aqueous liquid electrolyte (III), and side
reaction is thereby suppressed, leading to inhibition of cycle
deterioration.
[0354] The advantageous effect, however, is more pronounced when
the anode electrode active material containing the above specific
metal element is used for the non-aqueous liquid electrolyte
secondary battery (namely, first non-aqueous liquid electrolyte)
than when other anode electrode active material is used for the
non-aqueous liquid electrolyte secondary battery (namely, fourth
non-aqueous liquid electrolyte).
Examples
[0355] The present invention will be explained in further detail
below referring to examples. It is to be understood that any
modification is possible to these examples insofar as it does not
depart from the scope of the invention.
Example.cndot.Comparative Example Group I
Examples I-1 to I-14 and Comparative Examples I-1 to I-4
[0356] Non-aqueous liquid electrolyte secondary batteries were
assembled by the following procedure and their performance were
evaluated. The results are shown in Table I.
[0357] [Preparation of Anode Electrode]
Preparation of Silicon Alloy Anode Electrode: Examples I-1 to I-14,
Comparative Examples I-1, I-2
[0358] As anode electrode active material were used 73.2 weight
parts of silicon, a non-carbonaceous material, 8.1 weight parts of
copper and 12.2 weight parts of artificial graphite powder (product
of Timcar Co. "KS-6"). To the mixture were added 54.2 weight parts
of N-methylpyrrolidone solution, containing 12 weight parts of
polyvinylidene fluoride (hereafter abbreviated as "PVDF"), and 50
weight parts of N-methylpyrrolidone, and the mixture was made into
slurry using a disperser. The slurry obtained was coated uniformly
onto a copper film of 18 .mu.m thickness, which is a anode
electrode current collector. The coated film was first air-dried
and finally reduced pressure-dried overnight at 85.degree. C., and
then pressed to give an electrode density of about 1.5 gcm.sup.-3.
A disk of 12.5 mm diameter was stamped out to prepare the anode
electrode (silicon alloy anode electrode).
Preparation of Graphite Anode Electrode: Comparative Examples I-3,
I-4
[0359] As anode electrode was used 100 weight parts of artificial
graphite powder (product of Timcar Co. "KS-6"). To this were added
83.5 weight parts of N-methylpyrrolidone, containing 12 weight
parts of PVDF, and 50 weight parts of N-methylpyrrolidone, and the
mixture was made into slurry using a disperser. The slurry obtained
was coated uniformly onto a copper film of 18 .mu.m thickness,
which is a anode electrode current collector. The coated film was
first air-dried and finally reduced pressure-dried overnight at
85.degree. C., and then pressed to give an electrode density of
about 1.5 gcm.sup.-3. A disk of 12.5 mm diameter was punched out to
prepare the anode electrode (graphite anode electrode).
[0360] [Preparation of Cathode Electrode]
[0361] As cathode electrode active material was used 85 weight
parts of LiCoO.sub.2 (product of Nihon Kagaku Kogyo Co. "C5"). To
this were added 6 weight parts of carbon black (product of Denki
Kagaku Kogyo Co. "Denka Black") and 9 weight parts of
polyvinylidene fluoride KF-1000 (product of Kureha Kagaku Co.
"KF-1000"). After mixing, the mixture was dispersed into slurry
using N-methyl-2-pyrrolidone. The slurry obtained was coated
uniformly onto a aluminum film of 20 .mu.m thickness, which is the
cathode electrode current collector, so that its amount represents
90% of the theoretical capacity of the anode electrode. After
drying at 100.degree. C. for 12 hours, a disk of 12.5 mm diameter
was stamped out to prepare the cathode electrode.
[0362] [Preparation of Non-Aqueous Liquid Electrolyte]
[0363] [Specific carbonate], [other compound] and [specific
component] described in each [Example] and [Comparative Example] of
Table I appearing later were mixed in a ratio specified in the
Table. LiPF.sub.6 was dissolved as electrolyte salt at a
concentration of 1 moldm.sup.-3 to prepare the non-aqueous liquid
electrolyte (non-aqueous liquid electrolyte of Examples I-1 to I-14
and Comparative Examples I-1 to I-4).
[0364] [Preparation of Coin-Type Cell]
[0365] By using the above cathode electrode and anode electrode,
and the non-aqueous liquid electrolyte prepared in each Example and
Comparative Example, the coin-type cell (non-aqueous liquid
electrolyte secondary battery of Examples I-1 to I-14 and
Comparative Examples I-1 to I-4) was prepared by the following
procedure: at 25.degree. C., the cathode electrode was installed in
a stainless steel can-body which also functions as cathode
electrode current collector. Onto the cathode electrode installed,
the anode electrode was placed with a separator, made of
polyethylene and impregnated with the liquid electrolyte,
interposed in both electrode. Then the can-body was sealed by
caulking with a sealing pad, which also functions as anode
electrode current collector, with a gasket for insulation
interposed between the can-body and the pad, thereby the coin-type
cell being prepared. As anode electrode, the above-mentioned
silicon alloy anode electrode or graphite anode electrode was
selected and used, according to the description of [anode
electrode] column in each [Example] and [Comparative Example] of
Table I appearing later.
[0366] For the coin-type cell obtained by the above procedure
(non-aqueous liquid electrolyte secondary battery of Examples I-1
to I-14 and Comparative Examples I-1 to I-4), the discharge
capacity and discharge capacity retention were evaluated by the
following procedure: each coin-type cell was first charged with
constant current and constant voltage at the charge termination
voltage of 4.2V-3 mA and at the charge termination current of 0.15
.mu.A, and then discharged with constant current at the discharge
termination voltage of 3.0V-3 mA. This charge-discharge cycle was
repeated 50 times. Discharge capacities at the 1st, 10th and 50th
cycle were measured at this point. Discharge capacity retentions
after the 10th cycle and 50th cycle were calculated according to
the following formula.
discharge capacity retention (%)=100*(discharge capacity at the
10th or 50th cycle)/(discharge capacity at the 1st cycle)
[Mathematical Formula 1]
[0367] Discharge capacity at the 1st, 10th and 50th cycle and
discharge capacity retention (%) at the 10th and 50th cycle
obtained for the coin-type cell of each example and comparative
example are shown in the column [battery evaluation] of Table I
below. Values of discharge capacity shown in Table I indicate
capacity per unit weight of anode electrode active material
(mAhg.sup.-1). "Wt %" indicates "weight %".
[Table 1]
TABLE-US-00001 [0368] TABLE I battery evaluation non-aqueous liquid
electrolyte at the 10th cycle at the 50th cycle negative-
combination of non- discharge discharge discharge electrode aqueous
solvents capacity at discharge capacity discharge capacity active
(figures in parentheses the 1st cycle capacity retention capacity
retention Examples material means volume ratio)* specific
carbonate* (mAh/g) (mAh/g) rate (%) (mAh/g) rate (%) Examples I-1
Si Alloy EC + EPC(30:70) FEC(5 wt %) 609 508 83.4 357 58.7 I-2 EC +
EPC(30:70) VC(5 wt %) 605 495 81.9 352 58.2 I-3 EC + EPC(30:70)
DFEC(5 wt %) 608 505 83.1 357 58.7 I-4 EC + FEC + EPC(15:15:70)
(contained as saturated 612 520 84.9 367 59.9 cyclic carbonate) I-5
FEC + EPC(30:70) (contained as saturated 608 515 84.7 359 59.1
cyclic carbonate) I-6 FEC + EPC(30:70) VC(5 wt %) 603 520 86.3 341
56.5 I-7 EC + DPC + DEC(30:50:20) VC(5 wt %) 602 494 82.1 346 57.4
I-8 EC + EMFPC(30:70) (contained as specific 601 498 82.8 338 56.3
compound (I)) I-9 EC + PTFEC(30:70) (contained as specific 600 499
83.1 337 56.2 compound (I)) I-10 FEC + EMFPC(30:70) (contained as
saturated 604 511 84.6 361 59.7 cyclic carbonate and specific
compound (I)) I-11 FEC + PTFEC(30:70) (contained as saturated 606
516 85.1 357 58.9 cyclic carbonate and specific compound (I)) I-12
FEC + EMFPC(30:70) VC(5 wt %) 604 519 86.0 358 59.2 I-13 EC +
EPC(30:70) -- 602 499 82.9 333 55.3 I-14 EC + DPC + DEC(30:50:20)
-- 598 492 82.2 328 54.9 Comparative I-1 EC + DMC(30:70) -- 599 287
47.8 91 15.1 Examples I-2 EC + EMC(30:70) 603 321 53.2 113 18.7 I-3
graphite EC + EMC(30:70) -- 345 342 99.2 311 90.1 I-4 EC +
EPC(30:70) -- 338 332 98.3 290 85.8 EC: ethylene carbonate
(saturated cyclic carbonate) FEC: fluoroethylene carbonate
(saturated cyclic carbonate and specific carbonate; the number of
substituting F is 1) DFEC: 4,5-difluoroethylene carbonate
(saturated cyclic carbonate and specific carbonate; the number of
substituting F is 2) EPC: ethyl n-propyl carbonate (specific
compound (I); n = 3, m = 2) DPC: dipropyl carbonate (specific
compound (I); n = m = 3) PTFEC: n-propyl trifluoroethyl carbonate
(specific compound (I) and specific carbonate; n = 3, m = 2, the
number of substituing F is 3) EMFPC: ethyl 3-monofluoropropyl
carbonate (specific compound (I) and specific carbonate; n = 3, m =
2, the number of substituting F is 1) DEC: diethyl carbonate (other
chain carbonate) DMC: dimethyl carbonate (other chain carbonate)
EMC: ethyl methyl carbonate (other chain carbonate)
[0369] The results shown in Table I above indicate the
following.
[0370] In Comparative Examples I-1 and I-2, the non-aqueous liquid
electrolyte does not contain specific compound (I) (linear
carbonate represented by the above general formula (I)) and
therefore discharge capacity retention after cycle test is low in
either case.
[0371] In Comparative Examples I-3 and I-4, carbon material is used
as anode electrode active material. The non-aqueous liquid
electrolyte in comparative example I-3 does not contain specific
compound (I) and that in comparative example I-4 contains specific
compound (I). However, comparison between Comparative Example I-3
and Comparative Example I-4 indicates that the use of specific
compound (I) does not contribute to the improvement of discharge
capacity retention after cycle test, because the anode electrode
active material is carbon material. Therefore, when carbon material
is used as anode electrode active material, enhancing effect for
cycle characteristics can not be expected for specific compound
(I).
[0372] On the other hand, in the non-aqueous liquid electrolyte
secondary battery of Examples I-1 to I-12, where silicon alloy or
the like is used as anode electrode active material and the
non-aqueous liquid electrolyte containing specific compound (I),
the saturated cyclic carbonate and the specific carbonate, the
discharge capacity retention is improved remarkably in every case
in comparison with comparative example I-1 and I-2, which indicates
excellent cycle characteristics.
[0373] Furthermore, in Examples I-13 and I-14, where the
non-aqueous liquid electrolyte contains specific compound (I) and
the saturated cyclic carbonate but not the specific carbonate,
discharge capacity retention after cycle test is greatly improved
in comparison with Comparative Examples I-1 and I-2, although the
degree of improvement is slightly less than that for the above
Examples I-1 to I-12.
Example.cndot.Comparative Example Group II
Examples II-1 to II-28 and Comparative Examples II-1 to II-14
[0374] The non-aqueous liquid electrolyte secondary battery was
assembled by the following procedure and its performance was
evaluated. The results are shown in Tables II-1 to II-6.
[0375] [Preparation of Anode Electrode]
Preparation of Silicon Alloy Anode Electrode: Examples II-1 to
II-28, Comparative Examples II-1 to II-3, II-9, II-10
[0376] The anode electrode (silicon alloy anode electrode) was
prepared by the same method as described in the section
<Preparation of silicon alloy anode electrode> of the
above-mentioned [Example.cndot.Comparative Example Group I].
Preparation of Graphite Anode Electrode: Examples II-4 to II-8,
II-11 to II-14
[0377] The anode electrode (graphite anode electrode) was prepared
by the same method as described in the section <preparation of
graphite anode electrode> of the above-mentioned
[Example.cndot.Comparative Example Group I].
[0378] [Preparation of Cathode Electrode]
[0379] The cathode electrode was prepared by the same method as
described in the section <Preparation of cathode electrode>
of the above-mentioned [[Example.cndot.Comparative Example Group
I].
[0380] [Preparation of Non-Aqueous Liquid Electrolyte]
[0381] [Specific carbonate], [other compound] and [specific
component] described in [Example] and [Comparative Example] of
Table II-1 to II-6 appearing later were mixed in a ratio specified
in the Table. LiPF.sub.6 was dissolved as electrolyte salt at a
concentration of 1 moldm.sup.-3 to prepare the non-aqueous liquid
electrolyte (non-aqueous liquid electrolyte of Examples II-1 to
II-28 and Comparative Examples II-1 to II-14).
[0382] [Preparation of Coin-Type Cell]
[0383] By using the above cathode electrode and anode electrode,
and the non-aqueous liquid electrolyte prepared in each Example and
Comparative Example, the coin-type cell (non-aqueous liquid
electrolyte secondary battery of Examples II-1 to II-28 and
Comparative Examples II-1 to II-14) was prepared by the same
procedure as described in [Preparation of coin-type cell] of the
above-mentioned [Example.cndot.Comparative Example Group I].
[0384] [Evaluation of Coin-Type Cell (Discharge Capacity and
Discharge Capacity Retention)]
[0385] For the coin-type cell obtained above (non-aqueous liquid
electrolyte secondary battery of Examples II-1 to II-28 and
Comparative Examples II-1 to II-14), discharge capacity at the 1st
cycle and the 10th cycle was measured by the same procedure as
described above in [Evaluation of coin-type cell] of
Example.cndot.Comparative Example Group I]. Discharge capacity
retention at the 10th cycle was calculated according to the
following formula.
discharge capacity retention (%)=100*(discharge capacity at the
10th cycle)/(discharge capacity at the 1st cycle) [Mathematical
Formula 2]
[0386] Discharge capacity at the 1st and 10th cycle and discharge
capacity retention (%) at the 10th cycle obtained for the coin-type
cell of each example and comparative example are shown in the
column [battery evaluation] of Tables II-1 to II-6 below. Values of
discharge capacity shown in Tables II-1 to II-6 indicate capacity
per unit weight of anode electrode active material (mAhg.sup.-1).
Herein, "wt %" indicates "weight %", and "vt %" indicates "volume
%".
[Table 2]
TABLE-US-00002 [0387] TABLE II-1 battery evaluation non-aqueous
liquid electrolyte discharge discharge discharge specific capacity
at capacity at capacity negative carbonate other compound specific
compound (II) the 1st cycle the 10th cycle retention electrode
(concentration) (concentration) (concentration) (mAh g - 1) (mAh g
- 1) rate (%) Example II-1 Si alloy fluoroethylene ethylene
carbonate + bis(trimethylsilyl)sulfate 631 571 90.5 carbonate
diethyl carbonate (2 wt %) (5 wt %) (34 wt % + 59 wt %) Example
II-2 Si alloy fluoroethylene ethylene carbonate +
bis(trimethylsilyl)sulfate 627 560 89.3 carbonate diethyl carbonate
(1 wt %) (5 wt %) (34.5 wt % + 59.5 wt %) Example II-3 Si alloy
fluoroethylene diethyl carbonate bis(trimethylsilyl)sulfate 640 610
95.3 carbonate (59 wt %) (2 wt %) Example II-4 Si alloy
fluoroethylene ethylene carbonate + bis(trimethylsilyl)sulfate 638
595 93.3 carbonate diethyl carbonate (2 wt %) (20 wt %) (17.5 wt %
+ 60.5 wt %) Example II-5 Si alloy vinylene ethylene carbonate +
bis(trimethylsilyl)sulfate 622 535 86 carbonate diethyl carbonate
(2 wt %) (5 wt %) (34 wt % + 59 wt %) Example II-6 Si alloy 4,5-
ethylene carbonate + bis(trimethylsilyl)sulfate 636 590 92.7
difluoroethylene diethyl carbonate (2 wt %) carbonate (34 wt % + 59
wt %) (5 wt %) Example II-7 Si alloy fluoroethylene diethyl
carbonate bis(trimethylsilyl)sulfate 643 614 95.5 carbonate + (58
wt %) (2 wt %) vinylene carbonate Example II-8 Si alloy
fluoroethylene diethyl carbonate bis(trimethylsilyl)sulfate 642 612
95.4 carbonate + (58 wt %) (2 wt %) vinylethylene carbonate (38 wt
% + 2 wt %)
[Table 3]
TABLE-US-00003 [0388] TABLE II-2 battery evaluation non-aqueous
liquid electrolyte discharge discharge discharge specific capacity
at capacity at capacity negative carbonate other compound specific
compound (II) the 1st cycle the 10th cycle retention electrode
(concentration) (concentration) (concentration) (mAh g - 1) (mAh g
- 1) rate (%) Example II-9 Si alloy fluoroethylene ethylene
carbonate + bis(trimethylsilyl)sulfate 629 564 89.6 carbonate
diethyl carbonate (2 wt %) (5 wt %) (34 wt % + 59 wt %) Example
II-10 Si alloy 4,5- ethylene carbonate + bis(trimethylsilyl)sulfate
631 573 90.8 difluoroethylene diethyl carbonate (2 wt %) carbonate
(34 wt % + 59 wt %) (5 wt %) Example II-11 Si alloy fluoroethylene
diethyl carbonate bis(trimethylsilyl)sulfate 634 589 92.9 carbonate
(59 wt %) (2 wt %) Example II-12 Si alloy fluoroethylene diethyl
carbonate bis(trimethylsilyl)sulfate 640 602 94 carbonate + (58 wt
%) (2 wt %) vinylene carbonate (38 wt % + 2 wt %) Example II-13 Si
alloy fluoroethylene ethylene carbonate + bis[tris(2,2,2- 636 578
90.9 carbonate diethyl carbonate triethyl)]silylsulfate (5 wt %)
(34 wt % + 59 wt%) (2 wt %) Example II-14 Si alloy 4,5- ethylene
carbonate + bis[tris(2,2,2- 639 589 92.2 difluoroethylene diethyl
carbonate triethyl)]silylsulfate carbonate (34 wt % + 59 wt %) (2
wt %) (5 wt %) Example II-15 Si alloy fluoroethylene diethyl
carbonate bis[tris(2,2,2- 642 609 95 carbonate (59 wt %)
triethyl)]silylsulfate (2 wt %) Example II-16 Si alloy
fluoroethylene diethyl carbonate bis[tris(2,2,2- 645 616 95
carbonate + (58 wt %) triethyl)]silylsulfate vinylethylene (2 wt %)
carbonate (38 wt % + 2 wt %)
[Table 4]
TABLE-US-00004 [0389] TABLE II-3 battery evaluation non-aqueous
liquid electrolyte discharge discharge discharge specific capacity
at capacity at capacity negative carbonate other compound specific
compound (II) the 1st cycle the 10th cycle retention electrode
(concentration) (concentration) (concentration) (mAh g - 1) (mAh g
- 1) rate (%) Example II-17 Si alloy fluoroethylene ethylene
carbonate + bis(trimethylsilyl)sulfite 634 574 90.5 carbonate
diethyl carbonate (2 wt %) (5 wt %) (34 wt % + 59 wt %) Example
II-18 Si alloy 4,5- ethylene carbonate + bis(trimethylsilyl)sulfite
636 588 92.4 difluoroethylene diethyl carbonate (2 wt %) carbonate
(34.5 wt % + 59.5 wt %) (5 wt %) Example II-19 Si alloy
fluoroethylene diethyl carbonate bis(trimethylsilyl)sulfite 640 603
94.2 carbonate (59 wt %) (2 wt %) Example II-20 Si alloy
fluoroethylene diethyl carbonate bis(trimethylsilyl)sulfite 643 610
94.9 carbonate + (58 wt %) (2 wt %) vinylethylene carbonate (38 wt
% + 2 wt %) Example II-21 Si alloy none ethylene carbonate +
bis(trimethylsilyl)sulfite 618 510 82.5 diethyl carbonate (2 wt %)
(36 wt % + 62 wt %)
[Table 5]
TABLE-US-00005 [0390] TABLE II-4 battery evaluation non-aqueous
liquid electrolyte discharge discharge discharge specific capacity
at capacity at capacity negative carbonate other compound specific
compound (II) the 1st cycle the 10th cycle retention electrode
(concentration) (concentration) (concentration) (mAh g - 1) (mAh g
- 1) rate (%) Example II-22 Si alloy none ethylene carbonate +
bis(trimethylsilyl)sulfate 620 580 93.6 ethylmethyl carbonate (2 wt
%) (30 vt % + 70 vt %) Example II-23 Si alloy none ethylene
carbonate + bis(trimethylsilyl)sulfate 628 592 94.3 ethylmethyl
carbonate (4 wt %) (30 vt % + 70 vt %) Example II-24 Si alloy none
ethylene carbonate + bis(trimethylsilyl)sulfate 615 571 92.8
ethylmethyl carbonate (2 wt %) (30 vt % + 70 vt %) Example II-25 Si
alloy none ethylene carbonate + bis[tris(2,2,2- 608 571 93.9
ethylmethyl carbonate trifluoroethyl)]silylsulfate (30 vt % + 70 vt
%) (2 wt %) Example II-26 Si alloy none ethylene carbonate +
bis(trimethylsilyl)sulfite 605 559 92.4 ethylmethyl carbonate (2 wt
%) (30 vt % + 70 vt %) Example II-27 Si alloy vinylene ethylene
carbonate + bis(trimethylsilyl)sulfate 618 567 91.8 carbonate
ethylmethyl carbonate (2 wt %) (2 wt %) (30 vt % + 70 vt %) Example
II-28 Si alloy vinylene ethylene carbonate +
bis(trimethylsilyl)sulfite 603 553 91.7 carbonate ethylmethyl
carbonate (2 wt %) (2 wt %) (30 vt % + 70 vt %)
[Table 6]
TABLE-US-00006 [0391] TABLE II-5 battery evaluation non-aqueous
liquid electrolyte discharge discharge discharge specific capacity
at capacity at capacity negative carbonate other compound specific
compound (II) the 1st cycle the 10th cycle retention electrode
(concentration) (concentration) (concentration) (mAh g - 1) (mAh g
- 1) rate (%) Comparative Si alloy fluoroethylene ethylene
carbonate + none 615 494 80.3 Example II-1 carbonate diethyl
carbonate (5 wt %) (35 wt % + 60 wt %) Comparative Si alloy
vinylene ethylene carbonate + none 611 455 74.5 Example II-2
carbonate diethyl carbonate (5 wt %) (35 wt % + 60 wt %)
Comparative Si alloy none ethylene carbonate + none 601 341 56.7
Example II-3 diethyl carbonate (37 wt % + 63 wt %) Comparative
graphite none ethylene carbonate + none 338 274 81.2 Example II-4
diethyl carbonate (37 wt % + 63 wt %) Comparative graphite none
ethylene carbonate + bis(trimethylsilyl)sulfite 332 269 81 Example
II-5 diethyl carbonate (2 wt %) (36 wt % + 62 wt %) Comparative
graphite vinylene ethylene carbonate + none 342 301 88 Example II-6
carbonate diethyl carbonate (5 wt %) (35 wt % + 60 wt %)
Comparative graphite fluoroethylene ethylene carbonate +
bis(trimethylsilyl)sulfite 335 255 71.8 Example II-7 carbonate
diethyl carbonate (2 wt %) (5 wt %) (34 wt % + 59 wt %) Comparative
graphite fluoroethylene diethyl carbonate
bis(trimethylsilyl)sulfite 333 226 67.8 Example II-8 carbonate (59
wt %) (2 wt %)
[Table 7]
TABLE-US-00007 [0392] TABLE 11-6 battery evaluation non-aqueous
liquid electrolyte discharge discharge discharge specific capacity
at capacity at capacity negative carbonate other compound specific
compound (II) the 1st cycle the 10th cycle retention electrode
(concentration) (concentration) (concentration) (mAh g - 1) (mAh g
- 1) rate (%) Comparative Si alloy none ethylene carbonate + none
603 537 89.1 Example II-9 ethylmethyl carbonate (30 vt % + 70 vt %)
Comparative Si alloy vinylene ethylene carbonate + none 612 550
89.9 Example II-10 carbonate ethylmethyl carbonate (2 wt %) (30 vt
% + 70 vt %) Comparative graphite none ethylene carbonate + none
345 342 99.2 Example II-11 ethylmethyl carbonate (30 vt % + 70 vt
%) Comparative graphite vinylene ethylene carbonate + none 348 347
99.7 Example II-12 carbonate ethylmethyl carbonate (2 wt %) (30 vt
% + 70 vt %) Comparative graphite none ethylene carbonate +
bis(trimethylsilyl)sulfate 342 337 98.6 Example II-13 ethylmethyl
carbonate (2 wt %) (30 vt % + 70 vt %) Comparative graphite
vinylene ethylene carbonate + bis(trimethylsilyl)sulfate 344 340
98.9 Example II-14 carbonate ethylmethyl carbonate (2 wt %) (2 wt
%) (30 vt % + 70 vt %)
[0393] The results shown in Tables II-1 to II-6 above indicate the
following.
[0394] In Examples II-1 to II-20, II-27 and II-28, in which
specific compound (II) and the specific carbonate are contained in
the non-aqueous liquid electrolyte, the discharge capacity
retention after the cycle test is remarkably improved in comparison
with Comparative Example II-3, in which neither specific compound
(II) nor specific carbonate is contained in the non-aqueous liquid
electrolyte.
[0395] Further, in Examples II-21 to II-26, in which the
non-aqueous liquid electrolyte contains only specific compound (II)
and not specific carbonate, the discharge capacity retention after
the cycle test is remarkably improved also in comparison with
comparative example II-3, although the degree of improvement is a
little less than that observed in the above Examples II-1 to II-20,
II-27 and II-28.
[0396] On the other hand, in Comparative Examples II-1 and II-2
where the non-aqueous liquid electrolyte contains the specific
carbonate but not specific compound (II), the discharge capacity
retention increases but the degree of the increase is far less than
that observed in Examples II-1 to II-20, II-27 and II-28.
[0397] In Comparative Examples II-4 to II-8 and II-11 to II-14,
only carbon material is used as anode electrode active material and
in Comparative Examples II-4, II-9 and II-11, the non-aqueous
liquid electrolyte contains neither specific compound (II) nor
specific carbonate. In Comparative Example II-5, the non-aqueous
liquid electrolyte contains only specific compound (II) and not
specific carbonate. Comparison in discharge capacity retention
between Comparative Example II-4 and comparative example II-5
indicates that inclusion of specific compound (II) does not affect
discharge capacity retention.
[0398] The non-aqueous liquid electrolyte in Comparative Examples
II-6, II-10 and II-12 contains the specific carbonate but not
specific compound (II). Comparison in discharge capacity retention
between Comparative Examples II-4, II-9, II-11 and Comparative
Examples II-6, II-10, II-12 indicates that inclusion of the
specific carbonate improves discharge capacity retention.
[0399] On the other hand, comparison between Comparative Examples
II-7, II-8, II-14, whose non-aqueous liquid electrolyte contains
both the specific compound (II) and the specific carbonate, and
Comparative Examples II-4, II-9, II-11, whose non-aqueous liquid
electrolyte contains neither specific compound (II) or the specific
carbonate, indicates that discharge capacity retention is worse in
the former.
[0400] Discharge capacity in Examples II-1 to II-20, II-27, II-28,
where anode electrode active material consists of silicon alloy, is
higher than that in Comparative Examples II-4 to II-8, II-11 to
II-14, where anode electrode active material consists of carbon
material alone. And, as mentioned above, when anode electrode
active material consists of carbon material, inclusion of either
the specific carbonate or specific compound (II) in the non-aqueous
liquid electrolyte improves discharge capacity retention. However,
when specific compound (II) and the specific carbonate are both
included, discharge capacity retention is lower than when none of
these compound is included or when either one of these compounds is
included.
[0401] On the other hand, when anode electrode active material
consists of silicon alloy, a battery, based on the non-aqueous
liquid electrolyte containing only specific compound (II) and not
the specific carbonate, has lower discharge capacity retention than
a battery, based on the non-aqueous liquid electrolyte containing
neither of these compounds. However, a battery based on the
non-aqueous liquid electrolyte containing both specific compound
(II) and specific carbonate shows higher discharge capacity
retention.
Example.cndot.Comparative Example Group III
Examples III-1 to III-19 and Comparative Examples III-1 to
III-7
[0402] The non-aqueous liquid electrolyte secondary battery was
assembled by the following procedure and its performance was
evaluated. The results are shown in Table III-1 and III-2.
[0403] [Preparation of Anode Electrode]
Preparation of Silicon Alloy Anode Electrode: Examples III-1 to
II-11, Comparative Examples II-1 to II-4
[0404] The anode electrode (silicon alloy anode electrode) was
prepared by the same method as described in the section
<Preparation of silicon alloy anode electrode> of the
above-mentioned [Example.cndot.Comparative Example Group I].
Preparation of Graphite Anode Electrode: Examples III-12 to II-19,
Comparative Examples II-5 to II-7
[0405] The anode electrode (graphite anode electrode) was prepared
by the same method as described in the column <Preparation of
graphite anode electrode> of the above-mentioned
[Example.cndot.Comparative Example Group I].
[0406] [Preparation of Cathode Electrode]
[0407] The cathode electrode was prepared by the same method as
described in the column <Preparation of cathode electrode> of
the above-mentioned [Example.cndot.Comparative Example Group
I].
[0408] [Preparation of Non-Aqueous Liquid Electrolyte]
[0409] [Specific compound (III)] and [Specific carbonate] described
in [Example] and [Comparative Example] of Tables III-1 and III-2
appearing later were mixed in a ratio specified in the Table.
LiPF.sub.6 was dissolved further as electrolyte salt at a
concentration of 1 moldm.sup.-3 to prepare the non-aqueous liquid
electrolyte (non-aqueous liquid electrolyte of Examples III-1 to
III-19 and Comparative Examples III-1 to III-7).
[0410] [Preparation of Coin-Type Cell]
[0411] By using the cathode electrode, anode electrode, and
non-aqueous liquid electrolyte prepared in each Example and
Comparative Example, the coin-type cell (non-aqueous liquid
electrolyte secondary battery of Examples III-1 to III-19 and
Comparative Examples III-1 to III-7) was prepared by the same
procedure as described in [Preparation of coin-type cell] of the
above-mentioned [Example.cndot.Comparative Example Group I].
[0412] [Evaluation of Coin-Type Cell (Discharge Capacity and
Discharge Capacity Retention)]
[0413] For the non-aqueous liquid electrolyte secondary battery
obtained in Examples III-1 to III-11 and Comparative Examples III-1
to III-4 (coin-type cell), discharge capacity at the 1st cycle and
the 100th cycle was measured by the same procedure as described
above in [Evaluation of coin-type cell] of
[Example.cndot.Comparative Example Group I]. Discharge capacity
retention at the 100th cycle was calculated according to the
following formula.
discharge capacity retention (%)=100*(discharge capacity at the
100th cycle)/(discharge capacity at the 1st cycle) [Mathematical
Formula 3]
[0414] Further, for the non-aqueous liquid electrolyte secondary
battery obtained in Examples III-12 to III-19 and Comparative
Examples III-5 to III-7 (coin-type cell), discharge capacity at the
1st cycle and the 10th cycle was measured by the same procedure as
described above in [Evaluation of coin-type cell] of
[Example.cndot.Comparative Example Group I]. Discharge capacity
retention at the 10th cycle was calculated according to the
following formula.
discharge capacity retention (%)=100*(discharge capacity at the
10th cycle)/(discharge capacity at the 1st cycle) [Mathematical
Formula 4]
[0415] Discharge capacity retention at the 100th cycle (%) obtained
for the coin-type cell of each example and comparative example is
shown in the column [battery evaluation] of Tables III-1 and III-2.
Values of discharge capacity shown in Tables II-1 and II-2 indicate
capacity per unit weight of anode electrode active material
(mAhg.sup.-1). Herein, "wt %" indicates "weight %".
[Table 8]
TABLE-US-00008 [0416] TABLEIII-1 non-aqueous liquid electrolyte
battery evaluation specific compound (III) specific carbonate
negative discharge capacity structure amount name amount electrode
at the 100th cycle Example III-1 ##STR00022## 2 wt % vinylene
carbonate 2 wt % graphite 92% Example III-2 ##STR00023## 4 wt %
vinylene carbonate 2 wt % graphite 93% Example III-3 ##STR00024## 2
wt % vinylene carbonate 4 wt % graphite 95% Example III-4
##STR00025## 2 wt % vinylethylene carbonate 2 wt % graphite 90%
Example III-5 ##STR00026## 2 wt % fluoroethylene carbonate 2 wt %
graphite 90% Example III-6 ##STR00027## 2 wt % difluoroethylene
carbonate 2 wt % graphite 90% Example III-7 ##STR00028## 2 wt %
vinylene carbonate + vinylethylene carbonate 2 wt % + 2 wt %
graphite 93% Example III-8 ##STR00029## 2 wt % vinylene carbonate +
fluoroethylene carbonate 2 wt % + 2 wt % graphite 94% Example III-9
##STR00030## 2 wt % vinylene carbonate + difluoroethylene carbonate
2 wt % + 2 wt % graphite 94% Example III-10 ##STR00031## 2 wt %
vinylene carbonate 2 wt % graphite 93% Example III-11 ##STR00032##
2 wt % vinylene carbonate 2 wt % graphite 92% Comparative Example
III-1 -- -- vinylene carbonate 2 wt % graphite 88% Comparative
Example III-2 -- -- vinylene carbonate + vinylethylene carbonate 2
wt % + 2 wt % graphite 89% Comparative Example III-3 ##STR00033##
-- -- graphite 79% Comparative Example III-4 ##STR00034## -- --
graphite 75%
[Table 9]
TABLE-US-00009 [0417] TABLEIII-2 non-aqueous liquid electrolyte
battery evaluation specific compound (III) specific carbonate
negative discharge capacity structure amount name amount electrode
at the 10th cycle Example III-12 ##STR00035## 2 wt % vinylene
carbonate 2 wt % Si alloy 93.5% Example III-13 ##STR00036## 2 wt %
vinylene carbonate 2 wt % Si alloy 94.8% Example III-14
##STR00037## 2 wt % fluoroethylene carbonate 2 wt % Si alloy 94.3%
Example III-15 ##STR00038## 2 wt % difluoroethylene carbonate 2 wt
% Si alloy 94.5% Example III-16 ##STR00039## 2 wt % fluoroethylene
carbonate 30 wt % Si alloy 96.5% Example III-17 ##STR00040## 2 wt %
difluoroethylene carbonate 30 wt % Si alloy 96.3% Example III-18
##STR00041## 2 wt % vinylene carbonate + fluoroethylene carbonate 2
wt % Si alloy 95.9% Example III-19 ##STR00042## 2 wt % vinylene
carbonate + difluoroethylene carbonate 2 wt % Si alloy 96.1%
Comparative Example III-5 -- -- vinylene carbonate 2 wt % Si alloy
89.9% Comparative Example III-6 -- -- vinylene carbonate +
vinylethylene carbonate 2 wt % + 2 wt % Si alloy 91.2% Comparative
Example III-7 ##STR00043## 2 wt % -- -- Si alloy 89.2%
[0418] The results shown in Tables III-1 and III-2 above indicate
the following.
[0419] When graphite is used in the anode electrode, it is evident
that Examples III-1 to III-11, in which specific compound (III) and
the specific carbonate are contained in the non-aqueous liquid
electrolyte, give rise to a higher discharge capacity retention and
better cycle characteristics than Comparative Examples III-1 to
III-4.
[0420] Similar trend is also observed in the comparison between
Examples III-12 to III-19 and Comparative Examples III-5 to III-7,
where silicon alloy is used in the anode electrode.
INDUSTRIAL APPLICABILITY
[0421] The non-aqueous liquid electrolyte secondary battery of the
present invention is excellent in long-term charge-discharge cycle
characteristics and, therefore, can be used as power source of
notebook personal computers, pen-input personal computers, mobile
computers, electronic book players, cellular phones, portable
facsimiles, portable copiers, portable printers, headphone stereos,
video movies, liquid crystal televisions, handy cleaners, portable
CD players, mini disc players, transceivers, electronic databooks,
electronic calculators, memory cards, portable tape recorders,
radios, backup power sources, motors, illuminators, toys, game
machines, watches, stroboscopes, cameras, load leveling of power
etc. and can also be used for electric bicycle, electric scooter,
electric car etc.
[0422] Although the present invention was explained in detail
referring to certain embodiments, it is evident for those skilled
in the art that various changes or modifications can be made
thereto without departing from the spirit and scope of the present
invention.
[0423] The present application is based on Japanese Patent
Application (Patent Application No. 2004-326672) filed on Nov. 10,
2004, Japanese Patent Application (Patent Application No.
2005-055337) filed on Mar. 1, 2005 and Japanese patent Application
(Patent Application No. 2005-183846) filed on Jun. 23, 2005, and
their entireties are incorporated by reference.
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