U.S. patent application number 14/873747 was filed with the patent office on 2016-01-28 for electrolytic solution and battery.
The applicant listed for this patent is Sony Corporation. Invention is credited to Masayuki IHARA, Tadahiko KUBOTA, Hiroyuki YAMAGUCHI.
Application Number | 20160028124 14/873747 |
Document ID | / |
Family ID | 40382496 |
Filed Date | 2016-01-28 |
United States Patent
Application |
20160028124 |
Kind Code |
A1 |
IHARA; Masayuki ; et
al. |
January 28, 2016 |
ELECTROLYTIC SOLUTION AND BATTERY
Abstract
An electrolytic solution and battery are provided. The battery
includes a cathode, an anode and the electrolytic solution, and a
separator arranged between the cathode and the anode is impregnated
with the electrolytic solution. The solvent of the electrolytic
solution includes a sulfone compound having a sulfonyl fluoride
type structure.
Inventors: |
IHARA; Masayuki; (Fukushima,
JP) ; YAMAGUCHI; Hiroyuki; (Fukushima, JP) ;
KUBOTA; Tadahiko; (Kanagawa, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Sony Corporation |
Tokyo |
|
JP |
|
|
Family ID: |
40382496 |
Appl. No.: |
14/873747 |
Filed: |
October 2, 2015 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
12183153 |
Jul 31, 2008 |
9153836 |
|
|
14873747 |
|
|
|
|
Current U.S.
Class: |
429/338 ;
429/340 |
Current CPC
Class: |
C07C 309/80 20130101;
C07C 309/82 20130101; H01M 10/0568 20130101; C07C 309/86 20130101;
Y02E 60/10 20130101; H01M 10/0569 20130101; H01M 2300/0034
20130101; H01M 10/0567 20130101; H01M 10/052 20130101; C07C 309/81
20130101 |
International
Class: |
H01M 10/0569 20060101
H01M010/0569; H01M 10/0567 20060101 H01M010/0567; H01M 10/0568
20060101 H01M010/0568; H01M 10/052 20060101 H01M010/052 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 23, 2007 |
JP |
2007-216866 |
Aug 27, 2007 |
JP |
2007-219914 |
Aug 27, 2007 |
JP |
2007-219915 |
Claims
1. An electrolytic solution comprising: a solvent including a
sulfone compound represented by Chemical Formula 1: ##STR00049##
where R1 represents a z-valent group including carbon and one kind
or two or more kinds of elements selected from the group consisting
of hydrogen, oxygen and halogens, a sulfur atom in a sulfonyl group
is bonded to a carbon atom in R1, and z is an integer of 2 or
more.
2. The electrolytic solution according to claim 1, wherein in the
case where R1 is a straight-chain alkylene group or a halogenated
alkylene group, the number of carbon atoms is 2 or less.
3. The electrolytic solution according to claim 1, wherein the
sulfone compound represented by Chemical Formula 1 is a compound
represented by Chemical Formula 2: ##STR00050## where R2 represents
a divalent group including carbon and one kind or two or more kinds
of elements selected from hydrogen, oxygen and halogens, and a
sulfur atom in a sulfonyl group is bonded to a carbon atom in
R2.
4. The electrolytic solution according to claim 3, wherein in the
case where R2 is a straight-chain alkylene group or a halogenated
alkylene group, the number of carbon atoms is 2 or less.
5. The electrolytic solution according to claim 1, wherein the
solvent includes at least one kind selected from the group
consisting of a chain carbonate represented by Chemical Formula 3
which includes a halogen and a cyclic carbonate represented by
Chemical Formula 3 which includes a halogen: ##STR00051## where
R11, R12, R13, R14, R15 and R16 each represent a hydrogen group, a
halogen group, an alkyl group or a halogenated alkyl group, and at
least one of them is a halogen group or a halogenated alkyl group,
##STR00052## where R21, R22, R23 and R24 each represent a hydrogen
group, a halogen group, an alkyl group or a halogenated alkyl
group, and at least one of them is a halogen group or a halogenated
alkyl group.
6. The electrolytic solution according to claim 5, wherein the
chain carbonate represented by Chemical Formula 3 which includes a
halogen and the cyclic carbonate represented by Chemical Formula 4
which includes a halogen are each a compound including one
halogen.
7. The electrolytic solution according to claim 5, wherein the
chain carbonate represented by Chemical Formula 3 which includes a
halogen and the cyclic carbonate represented by Chemical Formula 4
which includes a halogen are each a compound including two
halogens.
8. The electrolytic solution according to claim 5, wherein the
chain carbonate represented by Chemical Formula 3 is selected from
the group consisting of: fluoromethyl methyl carbonate and
bis(fluoromethyl) carbonate, and the cyclic carbonate represented
by Chemical Formula 4 which includes a halogen is selected from the
group consisting of: 4-fluoro-1,3-dioxolane-2-one and
4,5-difluoro-1,3-dioxolane-2-one.
9. The electrolytic solution according to claim 1, wherein the
solvent includes at least one selected from the group consisting
of: a cyclic carbonate including an unsaturated bond, a sultone,
and an acid anhydride.
10. The electrolytic solution according to claim 1, comprising: an
electrolyte salt including at least one kind selected from the
group consisting of lithium hexafluorophosphate (LiPF.sub.6),
lithium tetrafluoroborate (LiBF.sub.4), lithium perchlorate
(LiClO.sub.4) and lithium hexafluoroarsenate (LiAsF.sub.6).
11. The electrolytic solution according to claim 1, comprising: an
electrolyte salt including at least one kind selected from the
group consisting of compounds represented by Chemical Formulas 11,
12 and 13:
LiN(C.sub.mF.sub.2m+1SO.sub.2)(C.sub.nF.sub.2n+1SO.sub.2) Chemical
Formula 11 where m and n each are an integer of 1 or more,
##STR00053## where R61 represents a straight-chain or branched
perfluoroalkylene group having 2 to 4 carbon atom,
LiC(C.sub.pF.sub.2p+1SO.sub.2)(C.sub.qF.sub.2q+1SO.sub.2)(C.sub.rF.sub.2r-
+1SO.sub.2) Chemical Formula 13 where p, q and r each are an
integer of 1 or more.
12. A secondary battery comprising a cathode, an anode and an
electrolytic solution according to claim 1.
13. The secondary battery according to claim 12, wherein a content
of the sulfone compound represented by Chemical Formula 14 in the
solvent is within a range from 0.01 wt % to 10 wt % both
inclusive.
14. The secondary battery according to claim 12, wherein the anode
includes an anode active material including a carbon material,
lithium metal or a material being capable of inserting and
extracting lithium and including at least one kind selected from
the group consisting of metal elements and metalloid elements.
15. The secondary battery according to claim 12, wherein the anode
includes an anode active material layer on an anode current
collector, and the anode active material layer is formed by at
least one kind of method selected from the group consisting of a
vapor-phase method, a liquid-phase method and a firing method.
16. An electrolytic solution comprising: a solvent including a
sulfone compound represented by Chemical Formula 55: ##STR00054##
where R1 is a chain group including a carbon-carbon unsaturated
bond or a derivative thereof.
17. The electrolytic solution according to claim 16, wherein a
halogen is substituted for at least a part of hydrogen in R1 shown
in Chemical Formula 55.
18. The electrolytic solution according to claim 17, wherein the
halogen is fluorine.
19. The electrolytic solution according to claim 16, wherein R1
shown in Chemical Formula 55 includes oxygen.
20. The electrolytic solution according to claim 16, wherein the
number of carbon atoms in R1 shown in Chemical Formula 55 is within
a range from 2 to 4 both inclusive.
21. The electrolytic solution according to claim 16, wherein a
content of the sulfone compound represented by Chemical Formula 55
in the solvent is within a range from 0.01 wt % to 5 wt % both
inclusive.
22. The electrolytic solution according to claim 16, wherein the
solvent includes at least one kind selected from the group
consisting of a chain carbonate represented by Chemical Formula 56
which includes a halogen and a cyclic carbonate represented by
Chemical Formula 57 which includes a halogen: ##STR00055## where
R11, R12, R13, R14, R15 and R16 each represent a hydrogen group, a
halogen group, an alkyl group or a halogenated alkyl group, and at
least one of them is a halogen group or a halogenated alkyl group,
##STR00056## where R21, R22, R23 and R24 each represent a hydrogen
group, a halogen group, an alkyl group or a halogenated alkyl
group, and at least one of them is a halogen group or a halogenated
alkyl group.
23. The electrolytic solution according to claim 22, wherein the
chain carbonate represented by Chemical Formula 56 is at least one
kind selected from the group consisting of fluoromethyl methyl
carbonate and bis(fluoromethyl) carbonate, and the cyclic carbonate
represented by Chemical Formula 57 which includes a halogen is at
least one kind selected from the group consisting of
4-fluoro-1,3-dioxolane-2-one and
4,5-difluoro-1,3-dioxolane-2-one.
24. The electrolytic solution according to claim 16, wherein the
solvent includes at least one selected from the group consisting
of: a cyclic carbonate including an unsaturated bond, a sultone,
and an acid anhydride.
25. The electrolytic solution according to claim 16, comprising: an
electrolyte salt including at least one kind selected from the
group consisting of lithium hexafluorophosphate, lithium
tetrafluoroborate, lithium perchlorate and lithium
hexafluoroarsenate.
26. The electrolytic solution according to claim 16, comprising: an
electrolyte salt including at least one kind selected from the
group consisting of compounds represented by Chemical Formulas 58,
59 and 60: ##STR00057## where X31 represents a Group 1A element or
a Group 2A element in the short form of the periodic table of the
elements, or aluminum, M31 represents a transition metal, or a
Group 3B element, a Group 4B element or a Group 5B element in the
short form of the periodic table of the elements, R31 represents a
halogen group, Y31 represents --OC--R32-CO--, --OC--CR33.sub.2- or
--OC--CO--, in which R32 represents an alkylene group, a
halogenated alkylene group, an arylene group or a halogenated
arylene group, and R33 represents an alkyl group, a halogenated
alkyl group, an aryl group or a halogenated aryl group, and a3 is
an integer of 1 to 4 both inclusive, and b3 is 0 or an integer of 2
or 4, and c3, d3, m3 and n3 each are an integer of 1 to 3 both
inclusive, ##STR00058## where X41 represents a Group 1A element or
a Group 2A element in the short form of the periodic table of the
elements, M41 represents a transition metal, or a Group 3B element,
a Group 4B element or a Group 5B element in the short form of the
periodic table of the elements, Y41 represents
--OC--(CR41.sub.2).sub.b4-CO--,
--R43.sub.2C--(CR42.sub.2).sub.c4-CO--,
--R43.sub.2C--(CR42.sub.2).sub.c4-CR43.sub.2-,
--R43.sub.2C--(CR42.sub.2).sub.c4-SO.sub.2--,
--O.sub.2S--(CR42.sub.2).sub.d4-SO.sub.2-- or
--OC--(CR42.sub.2).sub.d4-SO.sub.2--, in which R41 and R43 each
represent a hydrogen group, an alkyl group, a halogen group or a
halogenated alkyl group and at least one of them is a halogen group
or a halogenated alkyl group, and R42 represents a hydrogen group,
an alkyl group, a halogen group or a halogenated alkyl group, and
a4, e4 and n4 each are an integer of 1 or 2, b4 and d4 each are an
integer of 1 to 4 both inclusive, c4 is 0 or an integer of 1 to 4
both inclusive, and f4 and m4 each are an integer of 1 to 3 both
inclusive, ##STR00059## where X51 represents a Group 1A element or
a Group 2A element in the short form of the periodic table of the
elements, M51 represents a transition metal, or a Group 3B element,
a Group 4B element or a Group 5B element in the short form of the
periodic table of the elements, Rf represents a fluorinated alkyl
group having 1 to 10 carbon atoms or a fluorinated aryl group
having 1 to 10 carbon atoms, Y51 represents
--OC--(CR51.sub.2).sub.d5-CO--,
--R52.sub.2C--(CR51.sub.2).sub.d5-CO--,
--R52.sub.2C--(CR51.sub.2).sub.d5-CR52.sub.2-,
--R52.sub.2C--(CR51.sub.2).sub.d5-SO.sub.2--,
--O.sub.2S--(CR51.sub.2).sub.e5-SO.sub.2-- or
--OC--(CR51.sub.2).sub.e5-SO.sub.2--, in which R51 represents a
hydrogen group, an alkyl group, a halogen group or a halogenated
alkyl group, and R52 represents a hydrogen group, an alkyl group, a
halogen group or a halogenated alkyl group and at least one of them
is a halogen group or a halogenated alkyl group, and a5, f5 and n5
each are an integer of 1 or 2, b5, c5 and e5 each are an integer of
1 to 4 both inclusive, d5 is 0 or an integer of 1 to 4 both
inclusive, and g5 and m5 each are an integer of 1 to 3 both
inclusive.
27. The electrolytic solution according to claim 26, wherein the
compound represented by Chemical Formula 58 is at least one kind
selected from the group consisting of compounds represented by
Chemical Formula 61, the compound represented by Chemical Formula
59 is at least one kind selected from the group consisting of
compounds represented by Chemical Formula 62, and the compound
represented by Chemical Formula 60 is a compound represented by
Chemical Formula 63: ##STR00060## ##STR00061## ##STR00062##
28. The electrolytic solution according to claim 16, comprising: an
electrolyte salt including at least one kind selected from the
group consisting of compounds represented by Chemical Formulas 64,
65 and 66:
LiN(C.sub.mF.sub.2m+1SO.sub.2)(C.sub.nF.sub.2n+1SO.sub.2) Chemical
Formula 64 where m and n each are an integer of 1 or more,
##STR00063## where R61 represents a straight-chain or branched
perfluoroalkylene group having 2 to 4 carbon atom.
LiC(C.sub.pF.sub.2p+1SO.sub.2)(C.sub.qF.sub.2q+1SO.sub.2)(C.sub.rF.sub.2r-
+1SO.sub.2) Chemical Formula 66 where p, q and r each are an
integer of 1 or more.
29. A secondary battery comprising a cathode, an anode and an
electrolytic solution according to claim 16.
30. The secondary battery according to claim 29, wherein a content
of the sulfone compound represented by Chemical Formula 67 in the
solvent is within a range from 0.01 wt % to 5 wt % both
inclusive.
31. The secondary battery according to claim 29, wherein the anode
includes an anode active material including a carbon material,
lithium metal or a material being capable of inserting and
extracting lithium and including at least one kind selected from
the group consisting of metal elements and metalloid elements.
32. The secondary battery according to claim 29, wherein the anode
includes an anode active material including at least one kind
selected from the group consisting of a simple substance, an alloy
and a compound of silicon and a simple substance, an alloy and a
compound of tin.
33. The secondary battery according to claim 29, wherein the anode
includes an anode active material layer on an anode current
collector, and the anode active material layer is formed by at
least one kind of method selected from the group consisting of a
vapor-phase method, a liquid-phase method and a firing method.
Description
CROSS REFERENCES TO RELATED APPLICATIONS
[0001] The present application is a divisional of U.S. patent
application Ser. No. 12/183,153, filed on Jul. 31, 2008 and is set
to issue as U.S. Pat. No. 9,153,836 on Oct. 6, 2015, which claims
priority to Japanese Patent Application JP 2007-216866 filed in the
Japanese Patent Office on Aug. 23, 2007, Japanese Patent
Application JP 2007-219914 filed in the Japanese Patent Office on
Aug. 27, 2007, and Japanese Patent Application JP 2007-219915 filed
in the Japanese Patent Office on Aug. 27, 2007, the entire contents
of which are being incorporated herein by reference.
BACKGROUND
[0002] The present disclosure relates to an electrolytic solution
including a solvent, and a battery using the electrolytic
solution.
[0003] In recent years, portable electronic devices such as
camera-integrated VTRs (videotape recorders), cellular phones, or
laptop computers are widely used, and size and weight reduction in
the portable electronic devices and an increase in longevity of the
portable electronic devices have been strongly demanded.
Accordingly, as power sources for the portable electronic devices,
the development of batteries, specifically lightweight secondary
batteries capable of obtaining a high energy density have been
promoted.
[0004] Among them, a secondary battery (a so-called lithium-ion
secondary battery) using insertion and extraction of lithium for
charge-discharge reaction, a secondary battery (so-called lithium
metal secondary battery) using precipitation and dissolution of
lithium, or the like holds great promise, because the secondary
batteries are capable of obtaining a large energy density, compared
to a lead-acid battery or a nickel-cadmium battery.
[0005] As an electrolytic solution for the secondary batteries, a
combination of a carbonate-based solvent such as propylene
carbonate or diethyl carbonate and an electrolyte salt such as
lithium hexafluorophosphate is widely used (for example, refer to
Japanese Patent No. 3294400). It is because the combination has
high conductivity, and its potential is stable.
[0006] In addition, regarding the composition of an electrolytic
solution, to improve cycle characteristics, storage characteristics
and the like, techniques of including various sulfone compounds in
an electrolytic solution have been proposed. As the sulfone
compounds, a compound having a sulfonyl fluoride type structure
(for example, refer to Japanese Unexamined Patent Application
Publication Nos. 2002-359001, 2006-049112, 2006-049152 and
2006-294519), disulfonic anhydrides (for example, refer to Japanese
Unexamined Patent Application Publication Nos. 2004-022336 and
2006-344391 and Japanese Patent No. 3760539), disulfonate
derivatives (for example, refer to Japanese Unexamined Patent
Application Publication Nos. 2000-133304, 2006-351337 and
2007-080620) and the like are used.
[0007] In recent years, as portable electronic devices have higher
performance and more functions, the power consumption of the
portable electronic devices tends to increase. Accordingly,
secondary batteries used in the portable electronic devices are
frequently charged and discharged, thereby the cycle
characteristics of the secondary batteries easily decline.
Moreover, the portable electronic devices are widely used in
various fields, and there is a possibility that the secondary
batteries are exposed to a high-temperature atmosphere during
transport, in use or during carrying, so the storage
characteristics of the secondary batteries also decline easily.
Further, in the case where a secondary battery includes a
film-shaped package member, when the secondary battery is exposed
to a high-temperature atmosphere, the secondary battery is easily
swelled, so swelling characteristics are also important. Therefore,
further improvement in battery characteristics such as cycle
characteristics, storage characteristics and swelling
characteristics of the secondary batteries is desired.
[0008] In view of the foregoing, it is desirable to provide an
electrolytic solution and a battery which are capable of improving
battery characteristics.
SUMMARY
[0009] According to an embodiment, there is provided a first
electrolytic solution including: a solvent including a sulfone
compound represented by Chemical Formula 1.
##STR00001##
where R1 represents a z-valent group including carbon and one kind
or two or more kinds of elements selected from the group consisting
of hydrogen, oxygen and halogens, a sulfur atom in a sulfonyl group
is bonded to a carbon atom in R1, z is an integer of 2 or more, and
in the case where R1 is a straight-chain alkylene group or a
halogenated alkylene group, the number of carbon atoms is 2 or
less.
[0010] According to an embodiment, there is provided a first
secondary battery including a cathode, an anode and an electrolytic
solution, in which the electrolytic solution includes a sulfone
compound represented by Chemical Formula 2.
##STR00002##
where R1 represents a z-valent group including carbon and one kind
or two or more kinds of elements selected from the group consisting
of hydrogen, oxygen and halogens, a sulfur atom in a sulfonyl group
is bonded to a carbon atom in R1, z is an integer of 2 or more, and
in the case where R1 is a straight-chain alkylene group or a
halogenated alkylene group, the number of carbon atoms is 2 or
less.
[0011] According to an embodiment, there is provided a second
electrolytic solution including: a solvent including a sulfone
compound represented by Chemical Formula 3 and at least one kind
selected from the group consisting of a chain carbonate represented
by Chemical Formula 4 which includes a halogen and a cyclic
carbonate represented by Chemical Formula 5 which includes a
halogen.
##STR00003##
where R1 represents a z-valent group including carbon and one kind
or two or more kinds of elements selected from the group consisting
of hydrogen, oxygen and halogens, a sulfur atom in a sulfonyl group
is bonded to a carbon atom in R1, and z is an integer of 2 or
more.
##STR00004##
where R11, R12, R13, R14, R15 and R16 each represent a hydrogen
group, a halogen group, an alkyl group or a halogenated alkyl
group, and at least one of them is a halogen group or a halogenated
alkyl group.
##STR00005##
where R21, R22, R23 and R24 each represent a hydrogen group, a
halogen group, an alkyl group or a halogenated alkyl group, and at
least one of them is a halogen group or a halogenated alkyl
group.
[0012] According to an embodiment, there is provided a second
secondary battery including a cathode, an anode and an electrolytic
solution, in which the electrolytic solution includes a solvent
including a sulfone compound represented by Chemical Formula 6 and
at least one kind selected from the group consisting of a chain
carbonate represented by Chemical Formula 7 which includes a
halogen and a cyclic carbonate represented by Chemical Formula 8
which includes a halogen.
##STR00006##
where R1 represents a z-valent group including carbon and one kind
or two or more kinds of elements selected from the group consisting
of hydrogen, oxygen and halogens, a sulfur atom in a sulfonyl group
is bonded to a carbon atom in R1, and z is an integer of 2 or
more.
##STR00007##
where R11, R12, R13, R14, R15 and R16 each represent a hydrogen
group, a halogen group, an alkyl group or a halogenated alkyl
group, and at least one of them is a halogen group or a halogenated
alkyl group.
##STR00008##
where R21, R22, R23 and R24 each represent a hydrogen group, a
halogen group, an alkyl group or a halogenated alkyl group, and at
least one of them is a halogen group or a halogenated alkyl
group.
[0013] According to an embodiment, there is provided a third
electrolytic solution including: a solvent including a sulfone
compound represented by Chemical Formula 9.
##STR00009##
where R1 is a chain group including a carbon-carbon unsaturated
bond or a derivative thereof.
[0014] According to an embodiment, there is provided a third
secondary battery including a cathode, an anode and an electrolytic
solution, in which the electrolytic solution includes a solvent
including a sulfone compound represented by Chemical Formula
10.
##STR00010##
where R1 is a chain group including a carbon-carbon unsaturated
bond or a derivative thereof.
[0015] In the first electrolytic solution according to the
embodiment, the solvent includes the sulfone compound represented
by Chemical Formula 1. Therefore, compared to the case where the
sulfone compound is not included, or the case where another sulfone
compound is included, the chemical stability is improved. Thereby,
in the first secondary battery according to the embodiment, the
decomposition reaction of the electrolytic solution is prevented,
so cycle characteristics and storage characteristics are able to be
improved.
[0016] In the second electrolytic solution according to the
embodiment, the solvent includes the sulfone compound represented
by Chemical Formula 3 and at least one kind selected from the group
consisting of the chain carbonate represented by Chemical Formula 4
which includes a halogen and the cyclic carbonate represented by
Chemical Formula 5 which includes a halogen, so compared to the
case where neither of them is included, or the case where only one
of them is included, the chemical stability is improved. Thereby,
in the second secondary battery according to the embodiment, the
decomposition reaction of the electrolytic solution is prevented,
so battery characteristics such as cycle characteristics, storage
characteristics and swelling characteristics are able to be
improved.
[0017] In the third electrolytic solution according to the
embodiment, the solvent includes the sulfone compound represented
by Chemical Formula 9, so compared to the case where the sulfone
compound is not included, or the case where another sulfone
compound is included, the chemical stability is improved. Thereby,
in the third secondary battery according to the embodiment, the
decomposition reaction of the electrolytic solution is prevented,
so cycle characteristics are able to be improved.
[0018] Additional features and advantages are described herein, and
will be apparent from the following Detailed Description and the
figures.
BRIEF DESCRIPTION OF THE FIGURES
[0019] FIG. 1 is a sectional view showing the configuration of a
first secondary battery using an electrolytic solution according to
an embodiment;
[0020] FIG. 2 is a partially enlarged sectional view of a spirally
wound electrode body shown in FIG. 1;
[0021] FIG. 3 is an exploded perspective view of a fourth secondary
battery using the electrolytic solution according to the
embodiment; and
[0022] FIG. 4 is a sectional view showing a spirally wound
electrode body taken along a line IV-IV of FIG. 3.
DETAILED DESCRIPTION
[0023] Embodiments will be described in detail below referring to
the accompanying drawings.
First Embodiment
[0024] An electrolytic solution according to a first embodiment is
used in, for example, an electrochemical device such as a secondary
battery, and includes a solvent and an electrolyte salt dissolved
in the solvent.
[0025] The solvent includes one kind or two or more kinds of
sulfone compounds represented by Chemical Formula 11. It is because
the chemical stability of the electrolytic solution is improved.
The sulfone compound represented by Chemical Formula 11 has a
sulfonyl fluoride type structure in which a sulfonyl group
(--SO.sub.2--) and a fluorine group (--F) are bonded together.
##STR00011##
where R1 represents a z-valent group including carbon and one kind
or two or more kinds of elements selected from the group consisting
of hydrogen, oxygen and halogens, a sulfur atom in a sulfonyl group
is bonded to a carbon atom in R1, z is an integer of 2 or more, and
in the case where R1 is a straight-chain alkylene group or a
halogenated alkylene group, the number of carbon atoms is 2 or
less.
[0026] R1 in Chemical Formula 11 is a group having a carbon chain
or a carbon ring as a basic skeleton, and in the basic skeleton,
one kind or two or more kinds of elements selected from the group
consisting of hydrogen, oxygen and halogens may be included in any
form. The carbon chain may be a straight chain or a branched chain
having 1 or 2 or more side chains.
[0027] The above-described "form" means the number of elements, a
combination of elements and the like, and they are freely settable.
More specifically, as a form of hydrogen, for example, a part of an
alkylene group or an arylene group is cited. As a form of oxygen,
for example, an ether bond (--O--) or the like is cited. As a form
of halogens, for example, a part of a halogenated alkylene group or
the like is cited. The kind of halogen is not specifically limited,
but fluorine is preferable among halogens, because compared to
other halogens, the chemical stability of the electrolytic solution
is improved. In the above-described form of halogens, a halogen is
substituted for hydrogen in R1. In this case, the halogen may be
substituted for a part of hydrogen, or all of hydrogen. The forms
of hydrogen, oxygen and halogens may be any form other than the
above-described forms.
[0028] As long as R1 has the above-described structure, R1 may be
any group. However, a sulfur atom in a number z of sulfonyl groups
is not bonded to an atom (for example, an oxygen atom) except for a
carbon atom in R1, and the sulfur atom is necessarily bonded to a
carbon atom. Moreover, in the case where R1 is a straight-chain
alkylene group or a halogenated alkylene group, the number of
carbon atoms is limited to 2 or less (that is, 1 or 2). It is
because compared to the case where the number of carbon atoms is 3
or more, the chemical stability of the electrolytic solution is
improved, and superior compatibility is obtained. The "halogenated
alkylene group" is a group obtained by substituting a halogen for
at least a part of hydrogen in an alkylene group.
[0029] R1 may be a derivative of a group obtained by the
above-described forms, and in this case, any other elements except
for hydrogen, oxygen and halogens may be included as a constituent
element. The "derivative" means a group obtained by introducing one
or two or more substituent groups into the above-described groups,
and the kinds of the substituent groups are freely settable.
[0030] As long as the sulfone compound has a structure
corresponding to the structure shown in Chemical Formula 11, the
sulfone compound may have any structure as a whole. However, a
compound represented by Chemical Formula 12 is preferable, because
the number z (the number of sulfonyl fluoride parts) is reduced, so
in the electrolytic solution, high chemical stability is obtained,
and superior compatibility is obtained. The compound represented by
Chemical Formula 12 is a compound in which z in Chemical Formula 11
is z=2, and R1 is a divalent group.
##STR00012##
where R2 represents a divalent group including carbon and one kind
or two or more kinds of elements selected from the group consisting
of hydrogen, oxygen and halogens, a sulfur atom in a sulfonyl group
is bonded to a carbon atom in R2, and in the case where R2 is a
straight-chain alkylene group or a halogenated alkylene group, the
number of carbon atoms is 2 or less.
[0031] Examples of R2 which is a divalent group include a
straight-chain or branched alkylene group, an arylene group, a
group in which an arylene group and an alkylene group are bonded
together, a group in which an alkylene group and an ether bond are
bonded together, a halogenated group thereof, and the like. A
"divalent group including an arylene group and an alkylene group"
may be a group in which one arylene group and one alkylene group
are bonded together, or a group in which two alkylene groups are
bonded through one arylene group. The "group in which an alkylene
group and an ether bond are bonded together" means a group in which
two alkylene groups are bonded through one ether bond. The
"halogenated group thereof" means a group obtained by substituting
a halogen for at least a part of hydrogen in the above-described
alkylene group or the like. The above-described number or the
bonding order of the alkylene groups, the arylene groups or the
ether bonds is freely settable. R2 may be any group other than the
above-described groups.
[0032] In the case where R2 is a branched alkylene group, the
number of carbon atoms is freely settable. However, the number of
carbon atoms is preferably within a range from 2 to 10 both
inclusive, more preferably within a range from 2 to 6 both
inclusive, and more preferably within a range from 2 to 4 both
inclusive. Moreover, in the case where R2 is a group in which an
arylene group and an alkylene group are bonded together, a group in
which two alkylene groups are bonded through one arylene group is
preferable. The number of carbon atoms in this case is freely
settable, but the number of carbon atoms is preferably 8. It is
because in any of the cases, in the electrolytic solution, high
chemical stability is obtained, and superior compatibility is
obtained.
[0033] In the case where R2 is a group in which an alkylene group
and an ether bond are bonded together, the number of carbon atoms
are freely settable, but the number of carbon atoms is preferably
within a range from 2 to 12 both inclusive, more preferably within
a range from 4 to 12 both inclusive. In this case, in particular,
R2 is preferably a group represented by
--CH.sub.2--CH.sub.2--(O--CH.sub.2--CH.sub.2).sub.n--, and n is
more preferably within a range from 1 to 3 both inclusive. It is
because in the electrolytic solution, high chemical stability is
obtained, and superior compatibility is obtained.
[0034] Specific examples of R2 include straight-chain alkylene
groups (with two or less carbon atoms) represented by Chemical
Formulas 13(1) and 13(2), branched alkylene groups represented by
Chemical Formulas 14(1) to 14(9), arylene groups represented by
Chemical Formulas 15(1) to 15(3), groups in which an arylene group
and an alkylene group are bonded together represented by Chemical
Formulas 16(1) to 16(3), and groups in which an alkylene group and
an ether bond are bonded together represented by Chemical Formulas
17(1) to 17(13). In addition, as groups obtained by halogenating
the above-described groups, as shown in Chemical Formulas 18(1) to
18(9), groups obtained by halogenating groups in which an alkylene
group and an ether bond are bonded together are cited. In addition
to the groups in which an alkylene group and an ether bond are
bonded together, any other alkylene group or the like may be
halogenated.
##STR00013## ##STR00014## ##STR00015## ##STR00016##
[0035] Specific examples of the compound represented by Chemical
Formula 11 include compounds represented by Chemical Formulas 19(1)
to 19(5). It is because in the electrolytic solution, high chemical
stability is obtained, and superior solubility is obtained. For
confirmation, R1 in Chemical Formula 11 is a straight-chain
alkylene group in Chemical Formulas 19(1) and 19(2), a
straight-chain fluorinated alkylene group in Chemical Formulas
19(3) and 19(4), and an arylene group in Chemical Formula
19(5).
##STR00017##
[0036] Only one kind or a mixture of a plurality of kinds selected
from the compounds described as the compound represented by
Chemical Formula 11 may be used. As long as the compound has the
structure shown in Chemical Formula 11, the compound is not limited
to the compounds represented by Chemical Formulas 12 and 19.
[0037] The content of the sulfone compound represented by Chemical
Formula 11 in the solvent is freely settable. However, the content
is preferably within a range from 0.01 wt % to 10 wt % both
inclusive. It is because in the electrolytic solution, high
chemical stability is obtained. More specifically, when the content
is smaller than 0.01 wt %, there is a possibility that the chemical
stability of the electrolytic solution is not obtained sufficiently
and stably, and when the content is larger than 10 wt %, there is a
possibility that main electrical performance of an electrochemical
device (for example, capacity characteristics or the like in a
secondary battery) is not obtained sufficiently.
[0038] The solvent preferably includes one kind or two or more
kinds of nonaqueous solvents such as other organic solvents
together with the sulfone compound represented by Chemical Formula
11. Examples of the nonaqueous solvent include ethylene carbonate,
propylene carbonate, butylene carbonate, dimethyl carbonate,
diethyl carbonate, ethyl methyl carbonate, methyl propyl carbonate,
.gamma.-butyrolactone, .gamma.-valerolactone, 1,2-dimethoxyethane,
tetrahydrofuran, 2-methyltetrahydrofuran, tetrahydropyran,
1,3-dioxolane, 4-methyl-1,3-dioxolane, 1,3-dioxane, 1,4-dioxane,
methyl acetate, ethyl acetate, methyl propionate, ethyl propionate,
methyl butyrate, methyl isobutyrate, methyl trimethylacetate, ethyl
trimethylacetate, acetonitrile, glutaronitrile, adiponitrile,
methoxyacetonitrile, 3-methoxypropionitrile, N,N-dimethylformamide,
N-methylpyrrolidinone, N-methyloxazolidinone, N,N'-dimethyl
imidazolidinone, nitromethane, nitroethane, sulfolane, trimethyl
phosphate, dimethyl sulfoxide, dimethyl sulfoxide phosphate and the
like. Among them, at least one kind selected from the group
consisting of ethylene carbonate, propylene carbonate, dimethyl
carbonate, diethyl carbonate and ethyl methyl carbonate is
preferable, and a combination of a high-viscosity
(high-permittivity) solvent (for example, relative permittivity
.epsilon..gtoreq.30) such as ethylene carbonate or propylene
carbonate and a low-viscosity solvent (for example,
viscosity.ltoreq.1 mPas) such as dimethyl carbonate, ethyl methyl
carbonate or diethyl carbonate is more preferable. It is because
the dissociation property of the electrolyte salt and ion mobility
are improved.
[0039] Moreover, the solvent may include a cyclic carbonate
including an unsaturated bond, because the chemical stability of
the electrolytic solution is further improved. Examples of the
cyclic carbonate including an unsaturated bond include a vinylene
carbonate-based compound, a vinyl ethylene carbonate-based compound
and a methylene ethylene carbonate-based compound and the like.
[0040] Examples of the vinylene carbonate-based compound include
vinylene carbonate (1,3-dioxol-2-one), methyl vinylene carbonate
(4-methyl-1,3-dioxol-2-one), ethyl vinylene carbonate
(4-ethyl-1,3-dioxol-2-one), 4,5-dimethyl-1,3-dioxol-2-one,
4,5-diethyl-1,3-dioxol-2-one, 4-fluoro-1,3-dioxol-2-one,
4-trifluoromethyl-1,3-dioxol-2-one and the like.
[0041] Examples of the vinyl ethylene carbonate-based compound
include vinyl ethylene carbonate (4-vinyl-1,3-dioxolane-2-one),
4-methyl-4-vinyl-1,3-dioxolane-2-one,
4-ethyl-4-vinyl-1,3-dioxolane-2-one,
4-n-propyl-4-vinyl-1,3-dioxolane-2-one,
5-methyl-4-vinyl-1,3-dioxolane-2-one,
4,4-divinyl-1,3-dioxolane-2-one, 4,5-divinyl-1,3-dioxolane-2-one
and the like.
[0042] Examples of the methylene ethylene carbonate-based compound
include 4-methylene-1,3-dioxolane-2-one,
4,4-dimethyl-5-methylene-1,3-dioxolane-2-one,
4,4-diethyl-5-methylene-1,3-dioxolane-2-one and the like.
[0043] Only one kind or a mixture of a plurality of kinds selected
from them may be used. Among them, vinylene carbonate is
preferable, because a sufficient effect is obtained.
[0044] Moreover, the solvent preferably includes at least one kind
selected from the group consisting of a chain carbonate represented
by Chemical Formula 20 which includes a halogen as a constituent
element and a cyclic carbonate represented by Chemical Formula 21
which includes a halogen as a constituent element, because the
chemical stability of the electrolytic solution is further
improved.
##STR00018##
where R11, R12, R13, R14, R15 and R16 each represent a hydrogen
group, a halogen group, an alkyl group or a halogenated alkyl
group, and at least one of them is a halogen group or a halogenated
alkyl group.
##STR00019##
where R21, R22, R23 and R24 each represent a hydrogen group, a
halogen group, an alkyl group or a halogenated alkyl group, and at
least one of them is a halogen group or a halogenated alkyl
group.
[0045] R11 to R16 in Chemical Formula 20 may be the same as or
different from one another. The same holds for R21 to R24 in
Chemical Formula 21. The "halogenated alkyl group" which describes
R11 to R16 or R21 to R24 is a group obtained by substituting a
halogen for at least a part of hydrogen in an alkyl group. The kind
of the halogen is not specifically limited. However, at least one
kind selected from the group consisting of fluorine, chlorine and
bromine is cited, and among them, fluorine is preferable, because a
high effect is obtained. Any other halogen may be used.
[0046] In particular, as a halogenated carbonate, a compound
including two halogens (a dihalogenated carbonate) is preferable to
a compound including one halogen (a monohalogenated carbonate),
because a higher effect is obtained.
[0047] Examples of the chain carbonate represented by Chemical
Formula 20 which includes a halogen include fluoromethyl methyl
carbonate, bis(fluoromethyl) carbonate, difluoromethyl methyl
carbonate and the like. Only one kind or a mixture of a plurality
of kinds selected from them may be used. Among them,
bis(fluoromethyl) carbonate is preferable, because a high effect is
obtained.
[0048] In the case where at least one of R21 to R24 in Chemical
Formula 21 is an alkyl group or a halogenated alkyl group, the
alkyl group or the halogenated alkyl group is preferably a methyl
group, an ethyl group, a halogenated methyl group or a halogenated
ethyl group, because a high effect is obtained.
[0049] Examples of the cyclic carbonate represented by Chemical
Formula 21 which includes a halogen include compounds represented
by Chemical Formulas 22 and 23. More specifically,
4-fluoro-1,3-dioxolane-2-one in Chemical Formula 22(1),
4-chloro-1,3-dioxolane-2-one in Chemical Formula 22(2),
4,5-difluoro-1,3-dioxolane-2-one in Chemical Formula 22(3),
tetrafluoro-1,3-dioxolane-2-one in Chemical Formula 22(4),
4-fluoro-5-chloro-1,3-dioxolane-2-one in Chemical Formula 22(5),
4,5-dichloro-1,3-dioxolane-2-one in Chemical Formula 22(6),
tetrachloro-1,3-dioxolane-2-one in Chemical Formula 22(7),
4,5-bistrifluoromethyl-1,3-dioxolane-2-one in Chemical Formula
22(8), 4-trifluoromethyl-1,3-dioxolane-2-one in Chemical Formula
22(9), 4,5-difluoro-4,5-dimethyl-1,3-dioxolane-2-one in Chemical
Formula 22(10), 4-methyl-5,5-difluoro-1,3-dioxolane-2-one in
Chemical Formula 22(11), and
4-ethyl-5,5-difluoro-1,3-dioxolane-2-one in Chemical Formula 22(12)
are cited. Moreover, 4-trifluoromethyl-5-fluoro-1,3-dioxolane-2-one
in Chemical Formula 23(1),
4-trifluoromethyl-5-methyl-1,3-dioxolane-2-one in Chemical Formula
23(2), 4-fluoro-4,5-dimethyl-1,3-dioxolane-2-one in Chemical
Formula 23(3),
4,4-difluoro-5-(1,1-difluoroethyl)-1,3-dioxolane-2-one in Chemical
Formula 23(4), 4,5-dichloro-4,5-dimethyl-1,3-dioxolane-2-one in
Chemical Formula 23(5), 4-ethyl-5-fluoro-1,3-dioxolane-2-one in
Chemical Formula 23(6), 4-ethyl-4,5-difluoro-1,3-dioxolane-2-one in
Chemical Formula 23(7), 4-ethyl-4,5,5-trifluoro-1,3-dioxolane-2-one
in Chemical Formula 23(8), and
4-fluoro-4-methyl-1,3-dioxolane-2-one in Chemical Formula 23(9) are
cited.
[0050] Only one kind or a mixture of a plurality of kinds selected
from them may be used. Among them, 4-fluoro-1,3-dioxolane-2-one or
4,5-difluoro-1,3-dioxolane-2-one is preferable, and
4,5-difluoro-1,3-dioxolane-2-one is preferable. It is because they
are easily available, and a high effect is obtained. In particular,
as 4,5-difluoro-1,3-dioxolane-2-one, a trans-isomer is more
preferable than a cis-isomer.
##STR00020## ##STR00021##
[0051] Moreover, the solvent may include a sultone (cyclic
sulfonate) or an acid anhydride. It is because the chemical
stability of the electrolytic solution is further improved.
[0052] Examples of the sultone include propane sultone, propene
sultone and the like. Only one kind or a mixture of a plurality of
kinds selected from them may be used. Among them, propene sultone
is preferable. Further, the content of the sultone in the solvent
is preferably within a range from 0.5 wt % to 3 wt % both
inclusive. In any cases, a high effect is obtained.
[0053] Examples of the acid anhydride include a carboxylic
anhydride such as succinic anhydride, glutaric anhydride or maleic
anhydride, a disulfonic anhydride such as ethanedisulfonic
anhydride or propanedisulfonic anhydride, an anhydride of a
carboxylic acid and a sulfonic acid such as sulfobenzoic anhydride,
sulfopropionic anhydride, sulfobutyric anhydride, and the like.
Only one kind or a mixture of a plurality of kinds selected from
them may be used. Among them, sulfobenzoic anhydride is preferable.
Further, the content of the acid anhydride in the solvent is
preferably within a range from 0.5 wt % to 3 wt % both inclusive.
It is because in any case, a high effect is obtained.
[0054] For example, the intrinsic viscosity of the solvent is
preferably 10.0 mPas or less at 25.degree. C. It is because the
dissociation property of the electrolyte salt and ion mobility are
improved. The intrinsic viscosity in a state in which the
electrolyte salt is dissolved in the solvent (that is, the
intrinsic viscosity of the electrolytic solution) is also
preferably 10.0 mPas or less at 25.degree. C. because of the same
reason.
[0055] The electrolyte salt includes one kind or two or more kinds
of light metal salts such as a lithium salt. Examples of the
lithium salt include lithium hexafluorophosphate, lithium
tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate,
lithium tetraphenyl borate (LiB(C.sub.6H.sub.5).sub.4), lithium
methanesulfonate (LiCH.sub.3SO.sub.3), lithium
trifluoromethanesulfonate (LiCF.sub.3SO.sub.3), lithium
tetrachloroaluminate (LiAlCl.sub.4), lithium hexafluorosilicate
(Li.sub.2SiF.sub.6), lithium chloride (LiCl), lithium bromide
(LiBr) and the like. Among them, at least one kind selected from
the group consisting of lithium hexafluorophosphate, lithium
tetrafluoroborate, lithium perchlorate and lithium
hexafluoroarsenate is preferable, and lithium hexafluorophosphate
is preferable. It is because the resistance of the electrolytic
solution is reduced. In particular, a combination of lithium
hexafluorophosphate and lithium tetrafluoroborate is preferable. It
is because a high effect is obtained.
[0056] The electrolyte salt may include at least one kind selected
from the group consisting of compounds represented by Chemical
Formulas 24, 25 and 26. It is because a higher effect is obtained
in the case where they are used with the above-described lithium
hexafluorophosphate or the like. R33 in Chemical Formula 24 may be
the same as or different from each other. The same holds for R41 to
R43 in Chemical Formula 25 and R51 and R52 in Chemical Formula
26.
##STR00022##
where X31 represents a Group 1A element or a Group 2A element in
the short form of the periodic table of the elements, or aluminum,
M31 represents a transition metal, or a Group 3B element, a Group
4B element or a Group 5B element in the short form of the periodic
table of the elements, R31 represents a halogen group, Y31
represents --OC--R32-CO--, --OC--CR33.sub.2- or --OC--CO--, in
which R32 represents an alkylene group, a halogenated alkylene
group, an arylene group or a halogenated arylene group, and R33
represents an alkyl group, a halogenated alkyl group, an aryl group
or a halogenated aryl group, and a3 is an integer of 1 to 4 both
inclusive, b3 is 0 or an integer of 2 or 4, and c3, d3, m3 and n3
each are an integer of 1 to 3 both inclusive.
##STR00023##
where X41 represents a Group 1A element or a Group 2A element in
the short form of the periodic table of the elements, M41
represents a transition metal, or a Group 3B element, a Group 4B
element or a Group 5B element in the short form of the periodic
table of the elements, Y41 represents
--OC--(CR41.sub.2).sub.b4-CO--,
--R43.sub.2C--(CR42.sub.2).sub.c4-CO--,
--R43.sub.2C--(CR42.sub.2).sub.c4-CR43.sub.2-,
--R43.sub.2C--(CR42.sub.2).sub.c4-SO.sub.2--,
--O.sub.2S--(CR42.sub.2).sub.d4-SO.sub.2-- or
--OC--(CR42.sub.2).sub.d4-SO.sub.2--, in which R41 and R43 each
represent a hydrogen group, an alkyl group, a halogen group or a
halogenated alkyl group and at least one of them is a halogen group
or a halogenated alkyl group, and R42 represents a hydrogen group,
an alkyl group, a halogen group or a halogenated alkyl group, and
a4, e4 and n4 each are an integer of 1 or 2, b4 and d4 each are an
integer of 1 to 4 both inclusive, c4 is 0 or an integer of 1 to 4
both inclusive, and f4 and m4 each are an integer of 1 to 3 both
inclusive.
##STR00024##
where X51 represents a Group 1A element or a Group 2A element in
the short form of the periodic table of the elements, M51
represents a transition metal, or a Group 3B element, a Group 4B
element or a Group 5B element in the short form of the periodic
table of the elements, Rf represents a fluorinated alkyl group
having 1 to 10 carbon atoms or a fluorinated aryl group having 1 to
10 carbon atoms, Y51 represents --OC--(CR51.sub.2).sub.d5-CO--,
--R52.sub.2C--(CR51.sub.2).sub.d5-CO--,
--R52.sub.2C--(CR51.sub.2).sub.d5-CR52.sub.2-,
--R52.sub.2C--(CR51.sub.2).sub.d5-SO.sub.2--,
--O.sub.2S--(CR51.sub.2).sub.e5-SO.sub.2-- or
--OC--(CR51.sub.2).sub.e5-SO.sub.2--, in which R51 represents a
hydrogen group, an alkyl group, a halogen group or a halogenated
alkyl group, and R52 represents a hydrogen group, an alkyl group, a
halogen group or a halogenated alkyl group and at least one of them
is a halogen group or a halogenated alkyl group, and a5, f5 and n5
each are an integer of 1 or 2, b5, c5 and e5 each are an integer of
1 to 4 both inclusive, d5 is 0 or an integer of 1 to 4 both
inclusive, and g5 and m5 each are an integer of 1 to 3 both
inclusive.
[0057] Examples of the compound represented by Chemical Formula 24
include compounds represented by Chemical Formulas 27(1) to 27(6)
and the like. Examples of the compound represented by Chemical
Formula 25 include compounds represented by Chemical Formulas 28(1)
to 28(8) and the like. Examples of the compound represented by
Chemical Formula 26 include a compound represented by Chemical
Formula 29 and the like. Among them, the compound represented by
Chemical Formula 27(6) or Chemical Formula 28(6) is preferable,
because a high effect is obtained. As long as the compound has a
structure shown in Chemical Formulas 24 to 26, the compound is not
limited to the compounds represented by Chemical Formulas 27 to
29.
##STR00025##
[0058] Moreover, the electrolyte salt preferably includes at least
one kind selected from the group consisting of compounds
represented by Chemical Formulas 30, 31 and 32, because in the case
where they are used with the above-described lithium
hexafluorophosphate or the like, a higher effect is obtained. In
addition, m and n in Chemical Formula 30 may be the same as or
different from each other. The same holds for p, q and r in
Chemical Formula 32.
LiN(C.sub.mF.sub.2m+1SO.sub.2)(C.sub.nF.sub.2n+1SO.sub.2) Chemical
Formula 30
where m and n each are an integer of 1 or more.
##STR00026##
where R61 represents a straight-chain or branched perfluoroalkylene
group having 2 to 4 carbon atoms.
LiC(C.sub.pF.sub.2p+1SO.sub.2)(C.sub.qF.sub.2q+1SO.sub.2)(C.sub.rF.sub.2-
r+1SO.sub.2) Chemical Formula 32
where p, q and r each are an integer of 1 or more.
[0059] Examples of the chain compound represented by Chemical
Formula 30 include lithium bis(trifluoromethanesulfonyl)imide
(LiN(CF.sub.3SO.sub.2).sub.2), lithium
bis(pentafluoroethanesulfonyl)imide
(LiN(C.sub.2F.sub.5SO.sub.2).sub.2), imide lithium
(trifluoromethanesulfonyl)(pentafluoroethanesulfonyl)imide
(LiN(CF.sub.3SO.sub.2)(C.sub.2F.sub.5SO.sub.2)), lithium
(trifluoromethanesulfonyl)(heptafluoropropanesulfonyl)imide
(LiN(CF.sub.3SO.sub.2)(C.sub.3F.sub.7SO.sub.2)), lithium
(trifluoromethanesulfonyl)(nonafluorobutanesulfonyl)imide
(LiN(CF.sub.3SO.sub.2)(C.sub.4F.sub.9SO.sub.2)) and the like. Only
one kind or a mixture of a plurality of kinds selected from them
may be used.
[0060] Examples of the cyclic compound represented by Chemical
Formula 31 include compounds represented by Chemical Formula 33.
More specifically, lithium 1,2-perfluoroethanedisulfonylimide in
Chemical Formula 33(1), lithium 1,3-perfluoropropanedisulfonylimide
in Chemical Formula 33(2), lithium
1,3-perfluorobutanedisulfonylimide in Chemical Formula 33(3),
lithium 1,4-perfluorobutanedisulfonylimide in Chemical Formula
33(4) and the like are cited. Only one kind or a mixture of a
plurality of kinds selected from them may be used. Among them,
lithium 1,3-perfluoropropanedisulfonylimide is preferable, because
a high effect is obtained.
##STR00027##
[0061] As the chain compound represented by Chemical Formula 32,
for example, lithium tris(trifluoromethanesulfonyl)methide
(LiC(CF.sub.3SO.sub.2).sub.3) or the like is cited.
[0062] The content of the electrolyte salt is preferably within a
range from 0.3 mol/kg to 3.0 mol/kg both inclusive relative to the
solvent. It is because when the content of the electrolyte salt is
out of the range, there is a possibility that ionic conductivity is
extremely reduced.
[0063] In the electrolytic solution according to the embodiment,
the solvent includes the sulfone compound represented by Chemical
Formula 11, so compared to the case where the sulfone compound
represented by Chemical Formula 11 is not included, or the case
where another sulfone compound represented by Chemical Formula 34
is included, the chemical stability is improved. The sulfone
compound represented by Chemical Formula 34 is a compound having 3
carbon atoms in the case where R1 in Chemical Formula 11 is a
straight-chain alkylene group. Therefore, in the case where the
electrolytic solution is used in an electrochemical device such as
a secondary battery, decomposition reaction is prevented, so the
electrolytic solution is capable of contributing to an improvement
in cycle characteristics and storage characteristics. In this case,
when the sulfone compound represented by Chemical Formula 11 is the
compound represented by Chemical Formula 12, or when the content of
the sulfone compound represented by Chemical Formula 11 in the
solvent is within a range from 0.01 wt % to 10 wt % both inclusive,
a high effect is able to be obtained.
##STR00028##
[0064] In particular, when the solvent includes the cyclic
carbonate including an unsaturated bond, at least one kind selected
from the group consisting of the chain carbonate represented by
Chemical Formula 20 which includes a halogen and the cyclic
carbonate represented by Chemical Formula 21 which includes a
halogen, the sultone, or the acid anhydride, a higher effect is
able to be obtained. In particular, in the case where the solvent
includes at least one kind selected from the group consisting of
the chain carbonate represented by Chemical Formula 20 which
includes a halogen and the cyclic carbonate represented by Chemical
Formula 21 which includes a halogen, when a dihalogenated carbonate
rather than a monohalogenated carbonate is included, a higher
effect is able to be obtained.
[0065] Further, when the electrolyte salt includes at least one
kind selected from the group consisting of lithium
hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate
and lithium hexafluoroarsenate, at least one kind selected from the
group consisting of the compounds represented by Chemical Formulas
24 to 26, or at least one kind selected from the group consisting
of the compounds represented by Chemical Formulas 30 to 32, a
higher effect is able to be obtained.
[0066] Next, application examples of the above-described
electrolytic solution will be described below. As an example of the
electrochemical device, a secondary battery is used, and the
electrolytic solution is used in the secondary battery as
below.
First Secondary Battery
[0067] FIG. 1 shows a sectional view of a first secondary battery.
The secondary battery is, for example, a lithium-ion secondary
battery in which the capacity of an anode is represented on the
basis of insertion and extraction of lithium as an electrode
reactant.
[0068] The secondary battery includes a spirally wound electrode
body 20 which includes a cathode 21 and an anode 22 which are
spirally wound with a separator 23 in between, and a pair of
insulating plates 12 and 13 in a substantially hollow
cylindrical-shaped battery can 11. The battery can 11 is made of,
for example, a metal material such as nickel (Ni)-plated iron (Fe).
An end of the battery can 11 is closed, and the other end thereof
is opened. The pair of insulating plates 12 and 13 are arranged so
that the spirally wound electrode body 20 is sandwiched
therebetween, and the pair of insulating plates 12 and 13 extend in
a direction perpendicular to a peripheral winding surface. A
battery configuration using the cylindrical battery can 11 is
called a cylindrical type.
[0069] In the open end of the battery can 11, a battery cover 14,
and a safety valve mechanism 15 and a positive temperature
coefficient device (PTC device) 16 arranged inside the battery
cover 14 are mounted by caulking by a gasket 17, and the interior
of the battery can 11 is sealed. The battery cover 14 is made of,
for example, the same metal material as that of the battery can 11.
The safety valve mechanism 15 is electrically connected to the
battery cover 14 through the PTC device 16. In the safety valve
mechanism 15, when an internal pressure in the battery increases to
a certain extent or higher due to an internal short circuit or
external application of heat, a disk plate 15A is flipped so as to
disconnect the electrical connection between the battery cover 14
and the spirally wound electrode body 20. The PTC device 16 limits
a current by an increase in resistance with an increase in
temperature to prevent abnormal heat generation caused by a large
current. The gasket 17 is made of, for example, an insulating
material, and its surface is coated with asphalt.
[0070] A center pin 24 may be inserted into the center of the
spirally wound electrode body 20. In the spirally wound electrode
body 20, a cathode lead 25 made of a metal material such as
aluminum is connected to the cathode 21, and an anode lead 26 made
of a metal material such as nickel is connected to the anode 22.
The cathode lead 25 is welded to the safety valve mechanism 15 so
as to be electrically connected to the battery cover 14, and the
anode lead 26 is welded to the battery can 11 so as to be
electrically connected to the battery can 11.
[0071] FIG. 2 shows a partially enlarged view of the spirally wound
electrode body 20 shown in FIG. 1. The cathode 21 is formed by
arranging a cathode active material layer 21B on both sides of a
cathode current collector 21A having a pair of surfaces. The
cathode active material layer 21B may be arranged on only one side
of the cathode current collector 21A.
[0072] The cathode current collector 21A is made of, for example, a
metal material such as aluminum, nickel or stainless. For example,
as a cathode active material, the cathode active material layer 21B
includes one kind or two or more kinds of cathode materials capable
of inserting and extracting lithium, and may include another
material such as an electrical conductor or a binder, if
necessary.
[0073] Examples of the cathode material capable of inserting and
extracting lithium include chalgogenide not including lithium such
as iron sulfide (FeS.sub.2), titanium sulfide (TiS.sub.2),
molybdenum sulfide (MoS.sub.2), niobium selenide (NbSe.sub.2) or
vanadium oxide (V.sub.2O.sub.5), and a lithium-containing compound
including lithium, and the like.
[0074] Among them, the lithium-containing compound is preferable,
because a high voltage and a high energy density are able to be
obtained. Examples of such a lithium-containing compound include a
complex oxide including lithium and a transition metal element, or
a phosphate compound including lithium and a transition metal
element, and in particular, a lithium-containing compound including
at least one kind selected from the group consisting of cobalt,
nickel, manganese and iron is preferable, because a higher voltage
is obtained. The lithium-containing compound is represented by, for
example, a chemical formula Li.sub.xM1O.sub.2 or
Li.sub.yM2PO.sub.4. In the chemical formula, M1 and M2 represent
one or more kinds of transition metal elements. The values of x and
y depend on a charge-discharge state of the secondary battery, and
are generally within a range of 0.05.ltoreq.x.ltoreq.1.10 and
0.05.ltoreq.y.ltoreq.1.10, respectively.
[0075] Examples of the complex oxide including lithium and a
transition metal element include lithium-cobalt complex oxide
(Li.sub.xCoO.sub.2), lithium-nickel complex oxide
(Li.sub.xNiO.sub.2), lithium-nickel-cobalt complex oxide
(Li.sub.xNi.sub.1-zCo.sub.zO.sub.2 (z<1)),
lithium-nickel-cobalt-manganese complex oxide
(Li.sub.xNi.sub.(1-v-w)Co.sub.vMn.sub.wO.sub.2 (v+w<1)),
lithium-manganese complex oxide (LiMn.sub.2O.sub.4) having a spinel
structure and the like. Among them, a complex oxide including
nickel is preferable. It is because a high capacity is obtained,
and superior cycle characteristics are obtained. Examples of the
phosphate compound including lithium and a transition metal element
include a lithium-iron phosphate compound (LiFePO.sub.4), a
lithium-iron-manganese phosphate compound
(LiFe.sub.1-uMn.sub.uPO.sub.4 (u<1)) and the like.
[0076] In addition to the above-described materials, as the
above-described cathode material, for example, an oxide such as
titanium oxide, vanadium oxide or manganese dioxide, sulfur, or a
conductive polymer such as polyaniline or polythiophene is
cited.
[0077] The anode 22 is formed by arranging an anode active material
layer 22B on both sides of an anode current collector 22A having a
pair of surfaces. The anode active material layer 22B may be
arranged on only one side of the anode current collector 22A. The
anode current collector 22A is preferably made of a metal material
having good electrochemical stability, electrical conductivity and
mechanical strength. Examples of the metal material include copper
(Cu), nickel, stainless and the like, and among them, copper is
preferable, because high electrical conductivity is obtained.
[0078] The anode active material layer 22B includes one kind or two
or more kinds of anode materials capable of inserting and
extracting lithium as the anode active materials, and may include
another material such as an electrical conductor or a binder, if
necessary. The charge capacity of the anode material capable of
inserting and extracting lithium is preferably larger than the
charge capacity of the cathode active material.
[0079] As the anode material capable of inserting and extracting
lithium, for example, a carbon material is cited. Examples of such
a carbon material include graphitizable carbon, non-graphitizable
carbon with a (002) plane interval of 0.37 nm or more, graphite
with a (002) plane interval of 0.34 nm or more, and the like. More
specifically, kinds of pyrolytic carbon, kinds of coke, kinds of
graphite, glass-like carbon fibers, fired organic polymer compound
bodies, carbon fibers, activated carbon, kinds of carbon black and
the like are cited. Among them, kinds of coke include pitch coke,
needle coke, petroleum coke and so on, and the fired organic
polymer compound bodies are polymers such as a phenolic resin and a
furan resin which are carbonized by firing at an adequate
temperature. These carbon materials are preferable, because a
change in a crystal structure according to insertion and extraction
of lithium is very small, so a high energy density is obtained, and
superior cycle characteristics are obtained, and the carbon
materials also function as electrical conductors.
[0080] As the anode material capable of inserting and extracting
lithium, for example, a material being capable of inserting and
extracting lithium and including at least one kind selected from
the group consisting of metal elements and metalloid elements as a
constituent element is cited. Such an anode material is preferable,
because a high energy density is obtained. The anode material may
be the simple substance, an alloy or a compound of a metal element
or a metalloid element, or a material which includes a phase
including one kind or two or more kinds of them at least in part.
In the present application, the alloy means an alloy including two
or more kinds of metal elements as well as an alloy including one
or more kinds of metal elements and one or more kinds of metalloid
elements. Moreover, the alloy in the present application may
include a non-metal element. As the texture of the alloy, a solid
solution, a eutectic (eutectic mixture), an intermetallic compound
or the coexistence of two or more kinds selected from them is
cited.
[0081] Examples of the metal element or the metalloid element
included in the anode material include metal elements and metalloid
elements which are capable of forming an alloy with lithium. More
specifically, magnesium (Mg), boron (B), aluminum, gallium (Ga),
indium (In), silicon (Si), germanium (Ge), tin (Sn), lead (Pb),
bismuth (Bi), cadmium (Cd), silver (Ag), zinc (Zn), hafnium MB,
zirconium (Zr), yttrium (Y), palladium (Pd), platinum (Pt) or the
like is cited. Among them, at least one kind selected from the
group consisting of silicon and tin is preferable, because silicon
and tin have a large capability to insert and extract lithium, so a
high energy density is obtained
[0082] As the material including at least one kind selected from
the group consisting of silicon and tin, for example, at least one
kind selected from the group consisting of the simple substance,
alloys and compounds of silicon and the simple substance, alloys
and compounds of tin is cited. More specifically, a material
including the simple substance, an alloy or a compound of silicon,
the simple substance, an alloy or a compound of tin, or a material
including a phase of one kind or two or more kinds selected from
them at least in a part thereof is cited.
[0083] As an alloy of silicon, for example, an alloy including at
least one kind selected from the group consisting of tin, nickel,
copper, iron, cobalt (Co), manganese (Mn), zinc, indium, silver,
titanium, germanium, bismuth, antimony (Sb) and chromium as a
second constituent element in addition to silicon is cited. As an
alloy of tin, for example, an alloy including at least one kind
selected from the group consisting of silicon, nickel, copper,
iron, cobalt, manganese, zinc, indium, silver, titanium, germanium,
bismuth, antimony and chromium as a second constituent element in
addition to tin is cited.
[0084] As a compound of silicon or a compound of tin, for example,
a compound including oxygen or carbon is cited, and in addition to
silicon or tin, the compound may include the above-described second
constituent element.
[0085] In particular, as the material including at least one kind
selected from the group consisting of silicon and tin as a
constituent element, a material including a second constituent
element and a third constituent element in addition to tin as a
first constituent element is preferable. The second constituent
element includes at least one kind selected from the group
consisting of cobalt, iron, magnesium, titanium, vanadium (V),
chromium, manganese, nickel, copper, zinc, gallium, zirconium,
niobium (Nb), molybdenum (Mo), silver, indium, cerium (Ce),
hafnium, tantalum (Ta), tungsten (W), bismuth and silicon. The
third constituent element includes at least one kind selected from
the group consisting of boron, carbon, aluminum and phosphorus. It
is because when the second constituent element and the third
constituent element are included, cycle characteristics are
improved.
[0086] Among them, a CoSnC-containing material in which tin, cobalt
and carbon are included as constituent elements, and the carbon
content is within a range from 9.9 wt % to 29.7 wt % both
inclusive, and the ratio of cobalt to the total of tin and cobalt
(Co/(Sn+Co)) is within a range from 30 wt % to 70 wt % both
inclusive is preferable, because a high energy density is obtained
in such a composition range.
[0087] The CoSnC-containing material may include any other
constituent element, if necessary. As the other constituent
element, for example, silicon, iron, nickel, chromium, indium,
niobium, germanium, titanium, molybdenum, aluminum, phosphorus,
gallium, bismuth or the like is preferable, and two or more kinds
selected from them may be included. It is because a higher effect
is obtained.
[0088] The CoSnC-containing material includes a phase including
tin, cobalt and carbon, and the phase preferably has a low
crystalline structure or an amorphous structure. Moreover, in the
CoSnC-containing material, at least a part of carbon as a
constituent element is preferably bonded to a metal element or a
metalloid element as another constituent element. It is because
cohesion or crystallization of tin or the like is prevented.
[0089] As a measuring method for checking the bonding state of an
element, for example, X-ray photoelectron spectroscopy (XPS) is
used. In the XPS, the peak of the 1s orbit (C1s) of carbon in the
case of graphite is observed at 284.5 eV in an apparatus in which
energy calibration is performed so that the peak of the 4f orbit
(Au4f) of a gold atom is observed at 84.0 eV. Moreover, the peak of
C1s of surface contamination carbon is observed at 284.8 eV. On the
other hand, in the case where the charge density of the carbon
element increases, for example, in the case where carbon is bonded
to a metal element or a metalloid element, the peak of C1s is
observed in a region lower than 284.5 eV. In other words, in the
case where the peak of the composite wave of C1s obtained in the
CoSnC-containing material is observed in a region lower than 284.5
eV, at least a part of carbon included in the CoSnC-containing
material is bonded to the metal element or the metalloid element
which is another constituent element.
[0090] Moreover, in the XPS measurement, for example, the peak of
C1s is used to correct the energy axis of a spectrum. In general,
surface contamination carbon exists on a material surface, so the
peak of C1s of the surface contamination carbon is fixed at 284.8
eV, and the peak is used as an energy reference. In the XPS
measurement, the waveform of the peak of C1s is obtained as a form
including the peak of the surface contamination carbon and the peak
of carbon in the CoSnC-containing material, so the peak of the
surface contamination carbon and the peak of the carbon in the
CoSnC-containing material are separated by analyzing the waveform
through the use of, for example, commercially available software.
In the analysis of the waveform, the position of a main peak
existing on a lowest binding energy side is used as an energy
reference (284.8 eV).
[0091] Further, as the anode material capable of inserting and
extracting lithium, for example, a metal oxide or a polymer
compound capable of inserting and extracting lithium or the like is
cited. As the metal oxide, for example, iron oxide, ruthenium
oxide, molybdenum oxide or the like is cited, and as the polymer
compound, for example, polyacetylene, polyaniline, polypyrrole or
the like is cited.
[0092] A combination of the above-described anode materials capable
of inserting and extracting lithium may be used.
[0093] As the electrical conductor, for example, a carbon material
such as graphite, carbon black or ketjen black is cited. Only one
kind or a mixture of a plurality of kinds selected from them may be
used. As long as the electrical conductor is a material having
electrical conductivity, any metal material or any conductive
polymer may be used.
[0094] As the binder, for example, synthetic rubber such as styrene
butadiene-based rubber, fluorine-based rubber or ethylene propylene
diene or a polymer material such as polyvinylidene fluoride is
cited. Only one kind or a mixture of a plurality of kinds selected
from them may be used. However, as shown in FIG. 1, in the case
where the cathode 21 and the anode 22 are spirally wound, styrene
butadiene-based rubber or fluorine-based rubber which has high
flexibility is preferably used.
[0095] The separator 23 isolates between the cathode 21 and the
anode 22 so that lithium ions pass therethrough while preventing a
short circuit of a current due to contact between the cathode 21
and the anode 22. The separator 23 is made of, for example, a
porous film of a synthetic resin such as polytetrafluoroethylene,
polypropylene or polyethylene, or a porous ceramic film, and the
separator 23 may have a configuration in which two or more kinds of
the porous films are laminated. Among them, a porous film made of
polyolefin is preferable, because a short-circuit preventing effect
is superior, and the safety of the secondary battery by a shutdown
effect is able to be improved. In particular, polyethylene is
preferable, because a shutdown effect is able to be obtained within
a range from 100.degree. C. to 160.degree. C. both inclusive, and
electrochemical stability is superior. Moreover, polypropylene is
preferable, and any other resin having chemical stability such as a
resin prepared by copolymerizing or blending with polyethylene or
polypropylene may be used.
[0096] The separator 23 is impregnated with the above-described
electrolytic solution as a liquid electrolyte, because cycle
characteristics are improved.
[0097] When the secondary battery is charged, for example, lithium
ions are extracted from the cathode 21, and are inserted into the
anode 22 through the electrolytic solution. On the other hand, when
the secondary battery is discharged, for example, lithium ions are
extracted from the anode 22, and are inserted into the cathode 21
through the electrolytic solution.
[0098] The secondary battery is manufactured by the following
steps, for example.
[0099] At first, for example, the cathode active material layer 21B
is formed on both sides of the cathode current collector 21A to
form the cathode 21. In this case, the cathode active material
layer 21B is formed by the following steps. A cathode mixture
formed by mixing the cathode active material, the electrical
conductor and the binder is dispersed in a solvent to form
paste-form cathode mixture slurry, and the cathode mixture slurry
is applied to the cathode current collector 21A, and the cathode
mixture slurry is dried and compression molded by a roller press,
thereby the cathode active material layer 21B is formed. Moreover,
for example, by the same steps as those in the case of the cathode
21, the anode 22 is formed by forming the anode active material
layer 22B on the both sides of the anode current collector 22A.
[0100] Next, the cathode lead 25 is attached to the cathode current
collector 21A by welding or the like, and the anode lead 26 is
attached to the anode current collector 22A by welding or the like.
Then, the cathode 21 and the anode 22 are spirally wound with the
separator 23 in between so as to form the spirally wound electrode
body 20, and an end of the cathode lead 25 is welded to the safety
valve mechanism 15, and an end of the anode lead 26 is welded to
the battery can 11, and then the spirally wound electrode body 20
sandwiched between the pair of insulating plates 12 and 13 is
contained in the battery can 11. Next, the electrolyte salt is
dissolved in the solvent including the sulfone compound represented
by Chemical Formula 11 to prepare the electrolytic solution, and
then the electrolytic solution is injected into the battery can 11
so as to impregnate the separator 23 with the electrolytic
solution. Finally, the battery cover 14, the safety valve mechanism
15 and the PTC device 16 are fixed in an opened end portion of the
battery can 11 by caulking by the gasket 17. Thereby, the secondary
battery shown in FIGS. 1 and 2 is completed.
[0101] In the cylindrical type secondary battery, in the case where
the capacity of the anode 22 is represented on the basis of
insertion and extraction of lithium, the electrolytic solution
according to the embodiment is included, so the decomposition
reaction of the electrolytic solution is prevented. Therefore, the
cycle characteristics and the storage characteristics are able to
be improved. In particular, when the anode active material of the
anode 22 includes a material being capable of inserting and
extracting lithium, and including at least one kind selected from
the group consisting of metal elements and metalloid elements as a
constituent element, the electrolytic solution is decomposed more
easily, so a higher effect than that in the case where a carbon
material is included is able to be obtained. Other effects relating
to the secondary battery are the same as those in the
above-described electrolytic solution.
[0102] Next, second and third secondary batteries will be described
below, and like components are denoted by like numerals as of the
first secondary battery, and will not be further described.
Second Secondary Battery
[0103] The second secondary battery has the same configuration,
functions and effects as those of the first secondary battery,
except for the configuration of an anode 22 is different, and the
second secondary battery is manufactured by the same steps as those
in the first secondary battery.
[0104] The anode 22 has a configuration in which the anode active
material layer 22B is arranged on both sides of the anode current
collector 22A as in the case of the first secondary battery. As the
anode active material, the anode active material layer 22B
includes, for example, a material including silicon or tin as a
constituent element. More specifically, for example, the anode
active material includes the simple substance, an alloy or a
compound of silicon, or the simple substance, an alloy or a
compound of tin, and the anode active material may include two or
more kinds selected from them.
[0105] The anode active material layer 22B is formed by, for
example, a vapor-phase method, a liquid-phase method, a spraying
method or a firing method, or a combination of two or more methods
selected from them, and the anode active material layer 22B and the
anode current collector 22A are preferably alloyed in at least a
part of an interface therebetween. More specifically, in the
interface, a constituent element of the anode current collector 22A
may be diffused into the anode active material layer 22B, or a
constituent element of the anode active material layer 22B may be
diffused into the anode current collector 22A, or they may be
diffused into each other, because a fracture of the anode active
material layer 22B due to swelling and shrinkage thereof according
to charge and discharge is prevented, and the electronic
conductivity between the anode active material layer 22B and the
anode current collector 22A is improved.
[0106] As the vapor-phase method, for example, a physical
deposition method or a chemical deposition method, more
specifically, a vacuum deposition method, a sputtering method, an
ion plating method, a laser ablation method, a thermal CVD
(chemical vapor deposition) method, a plasma chemical vapor
deposition method or the like is cited. As the liquid-phase method,
a known technique such as electrolytic plating or electroless
plating may be used. In the firing method, for example, a
particulate anode active material is mixed with a binder or the
like to form a mixture, and the mixture is dispersed in a solvent
and is applied, and then the mixture is heated at a higher
temperature than the melting point of the binder or the like. As
the firing method, a known technique such as, for example, an
atmosphere firing method, a reaction firing method or a hot press
firing method is cited.
Third Secondary Battery
[0107] The third secondary battery is a so-called lithium metal
secondary battery in which the capacity of the anode 22 is
represented on the basis of precipitation and dissolution of
lithium. The secondary battery has the same configuration as that
of the first secondary battery, except that the anode active
material layer 22B is made of lithium metal, and the secondary
battery is manufactured by the same steps as those in the first
secondary battery.
[0108] The secondary battery uses lithium metal as the anode active
material, thereby a higher energy density is able to be obtained.
The anode active material layer 22B may exist at the time of
assembling, or may not exist at the time of assembling, and may be
made of lithium metal precipitated at the time of charge. Moreover,
the anode active material layer 22B may be used also as a current
collector, thereby the anode current collector 22A may be
removed.
[0109] When the secondary battery is charged, lithium ions are
extracted from the cathode 21, and the lithium ions are
precipitated on the surface of the anode current collector 22A as
lithium metal through the electrolytic solution. When the secondary
battery is discharged, the lithium metal is dissolved from the
anode active material layer 22B as lithium ions, and the lithium
ions are inserted into the cathode 21 through the electrolytic
solution.
[0110] In the cylindrical type secondary battery, in the case where
the capacity of the anode 22 is represented on the basis of
precipitation and dissolution of lithium, the electrolytic solution
according to the embodiment is included, so the cycle
characteristics and the storage characteristics are able to be
improved. Other effects relating to the secondary battery are the
same as those in the first secondary battery.
Fourth Secondary Battery
[0111] FIG. 3 shows an exploded perspective view of a fourth
secondary battery. In the secondary battery, a spirally wound
electrode body 30 to which a cathode lead 31 and an anode lead 32
are attached is contained in film-shaped package members 40, and a
battery configuration using the film-shaped package members 40 is
called a laminate film type.
[0112] The cathode lead 31 and the anode lead 32 are drawn, for
example, from the interiors of the package members 40 to outside in
the same direction. The cathode lead 31 is made of, for example, a
metal material such as aluminum, and the anode lead 32 are made of,
for example, a metal material such as copper, nickel or stainless.
The metal materials of which the cathode lead 31 and the anode lead
32 are made each have a sheet shape or a mesh shape.
[0113] The package members 40 are made of, for example, a
rectangular aluminum laminate film including a nylon film, aluminum
foil and a polyethylene film which are bonded in this order. The
package members 40 are arranged so that the polyethylene film of
each of the package members 40 faces the spirally wound electrode
body 30, and edge portions of the package members 40 are adhered to
each other by fusion bonding or an adhesive. An adhesive film 41 is
inserted between the package members 40 and the cathode lead 31 and
the anode lead 32 for preventing the entry of outside air. The
adhesive film 41 is made of, for example, a material having
adhesion to the cathode lead 31 and the anode lead 32, for example,
a polyolefin resin such as polyethylene, polypropylene, modified
polyethylene or modified polypropylene.
[0114] In addition, the package members 40 may be made of a
laminate film with any other configuration, a polymer film such as
polypropylene or a metal film instead of the above-described
three-layer aluminum laminate film.
[0115] FIG. 4 shows a sectional view of the spirally wound
electrode body 30 taken along a line IV-IV of FIG. 3. The spirally
wound electrode body 30 is formed by laminating a cathode 33 and an
anode 34 with a separator 35 and an electrolyte 36 in between, and
then spirally winding them, and an outermost portion of the
spirally wound electrode body 30 is protected with a protective
tape 37.
[0116] The cathode 33 is formed by arranging a cathode active
material layer 33B on both sides of a cathode current collector
33A. The anode 34 is formed by arranging an anode active material
layer 34B on both sides of an anode current collector 34A, and the
anode 34 is arranged so that the anode active material layer 34B
faces the cathode active material layer 33B. The configurations of
the cathode current collector 33A, the cathode active material
layer 33B, the anode current collector 34A, the anode active
material layer 34B and the separator 35 are the same as those of
the cathode current collector 21A, the cathode active material
layer 21B, the anode current collector 22A, the anode active
material layer 22B and the separator 23 in the above-described
first, second and third secondary batteries, respectively.
[0117] The electrolyte 36 includes the above-described electrolytic
solution and a polymer compound holding the electrolytic solution,
and is a so-called gel electrolyte. The gel electrolyte is
preferable, because the gel electrolyte is able to obtain high
ionic conductivity (for example, 1 mS/cm or over at room
temperature), and leakage of an electrolyte from the secondary
battery is prevented.
[0118] Examples of the polymer compound include polyacrylonitrile,
polyvinylidene fluoride, a copolymer of polyvinylidene fluoride and
polyhexafluoropyrene, polytetrafluoroethylene,
polyhexafluoropropylene, polyethylene oxide, polypropylene oxide,
polyphosphazene, polysiloxane, polyvinyl acetate, polyvinyl
alcohol, polymethyl methacrylate, polyacrylic acids,
polymethacrylic acids, styrene-butadiene rubber, nitrile-butadiene
rubber, polystyrene, polycarbonate and the like. Only one kind or a
mixture of a plurality of kinds selected from them may be used. In
particular, in terms of electrochemical stability,
polyacrylonitrile, polyvinylidene fluoride,
polyhexafluoropropylene, polyethylene oxide or the like is
preferable. The content of the polymer compound in the electrolytic
solution depends on compatibility between them, but is preferably
within a range from 5 wt % to 50 wt % both inclusive.
[0119] The composition of the electrolytic solution is the same as
that of the electrolytic solution in the first secondary battery.
The solvent in this case has a wide concept including not only a
liquid solvent but also a solvent having ionic conductivity capable
of dissociating the electrolyte salt. Therefore, in the case where
a polymer compound having ionic conductivity is used, the polymer
compound is included in the concept of the solvent. In particular,
in the case where a liquid solvent is used, propylene carbonate is
preferably used, because swelling of the secondary battery is
prevented.
[0120] In addition, instead of the electrolyte 36 in which the
polymer compound holds the electrolytic solution, the electrolytic
solution may be used as it is. In this case, the separator 35 is
impregnated with the electrolytic solution.
[0121] The secondary battery may be manufactured by the following
three kinds of manufacturing methods, for example.
[0122] In a first manufacturing method, by the same steps as those
in the method of manufacturing the first secondary battery, at
first, the cathode active material layer 33B is formed on both
sides of the cathode current collector 33A so as to form the
cathode 33, and the anode active material layer 34B is formed on
both sides of the anode current collector 34A so as to form the
anode 34. Next, the gel electrolyte 36 is formed by preparing a
precursor solution including the electrolytic solution, the polymer
compound and a solvent, applying the precursor solution to the
cathode 33 and the anode 34, and volatilizing the solvent. Then,
the cathode lead 31 and the anode lead 32 are attached to the
cathode current collector 33A and the anode current collector 34A,
respectively. Next, after the cathode 33 on which the electrolyte
36 is formed and the anode 34 on which the electrolyte 36 is formed
are laminated with the separator 35 in between to form a laminate,
the laminate is spirally wound in a longitudinal direction, and the
protective tape 37 is bonded to an outermost portion of the
laminate so as to form the spirally wound electrode body 30.
Finally, for example, the spirally wound electrode body 30 is
sandwiched between two film-shaped package members 40, and edge
portions of the package members 40 are adhered to each other by
thermal fusion bonding or the like to seal the spirally wound
electrode body 30 in the package members 40. At this time, the
adhesive film 41 is inserted between the cathode lead 31 and the
anode lead 32, and the package members 40. Thereby, the secondary
battery shown in FIGS. 3 and 4 is completed.
[0123] In a second manufacturing method, at first, after the
cathode lead 31 and the anode lead 32 are attached to the cathode
33 and the anode 34, respectively, the cathode 33 and the anode 34
are laminated with the separator 35 in between to form a laminate,
and the laminate is spirally wound, and the protective tape 37 is
bonded to an outermost portion of the spirally wound laminate so as
to form a spirally wound body as a precursor body of the spirally
wound electrode body 30. Next, the spirally wound body is
sandwiched between two film-shaped package members 40, and the edge
portions of the package members 40 except for edge portions on one
side are adhered by thermal fusion bonding or the like to form a
pouched package, thereby the spirally wound body is contained in
the package members 40. An electrolytic composition which includes
the electrolytic solution, monomers as materials of a polymer
compound and a polymerization initiator and, if necessary, any
other material such as a polymerization inhibitor is prepared, and
the composition is injected in the package members 40, and then an
opened portion of the package members 40 are sealed by thermal
fusion bonding or the like. Finally, the monomers are polymerized
by applying heat to form the polymer compound, thereby the gel
electrolyte 36 is formed. Thus, the secondary battery is
completed.
[0124] In a third manufacturing method, as in the case of the first
manufacturing method, the spirally wound body is formed, and the
spirally wound body is contained in the package members 40, except
that the separator 35 with both surfaces coated with a polymer
compound is used. As the polymer compound applied to the separator
35, for example, a polymer including vinylidene fluoride as a
component, that is, a homopolymer, a copolymer, a multicomponent
copolymer, or the like is cited. More specifically, polyvinylidene
fluoride, a binary copolymer including vinylidene fluoride and
hexafluoropropylene as components, a ternary copolymer including
vinylidene fluoride, hexafluoropropylene and
chlorotrifluoroethylene as components is cited. The polymer
compound may include one kind or two or more kinds of other polymer
compounds in addition to the above-described polymer including
vinylidene fluoride as a component. Next, after the electrolytic
solution is prepared, and injected into the package members 40, an
opened portion of the package members 40 is sealed by thermal
fusion bonding or the like. Finally, the package members 40 are
heated while being weighted so that the separator 35 is brought
into close contact with the cathode 33 and the anode 34 with the
polymer compound in between. Thereby, the polymer compound is
impregnated with the electrolytic solution, and the polymer
compound is gelatinized so as to form the electrolyte 36, so the
secondary battery is completed.
[0125] In the third manufacturing method, compared to the first
manufacturing method, swelling of the secondary battery is
prevented. Moreover, in the third manufacturing method, compared to
the second manufacturing method, monomers as the materials of the
polymer compound, the solvent and the like hardly remain in the
electrolyte 36, and a step of forming the polymer compound is
controlled well, so sufficient adhesion between the cathode 33,
anode 34 and the separator 35, and the electrolyte 36 is
obtained.
[0126] The functions and effects of the laminate type secondary
battery are the same as those in the first, second and third
secondary batteries.
Second Embodiment
[0127] An electrolytic solution according to a second embodiment is
used in, for example, an electrochemical device such as a secondary
battery as in the case of the above-described electrolytic solution
according to the first embodiment, and includes a solvent and an
electrolyte salt dissolved in the solvent.
[0128] The solvent includes a sulfone compound represented by
Chemical Formula 35 (hereinafter also simply referred to "sulfone
compound") and at least one kind selected from the group consisting
of a chain carbonate represented by Chemical Formula 36 which
includes a halogen as a constituent element, and a cyclic carbonate
represented by Chemical Formula 37 which includes a halogen as a
constituent element (hereinafter simply and collectively called
"halogenated carbonates"). It is because when a combination of the
above-described sulfone compound and the halogenated carbonates is
included, compared to the case where neither of them is included or
the case where only one of them is included, the chemical stability
of the electrolytic solution is improved.
##STR00029##
where R1 represents a z-valent group including carbon and one kind
or two or more kinds of elements selected from the group consisting
of hydrogen, oxygen and halogens, a sulfur atom in a sulfonyl group
is bonded to a carbon atom in R1, and z is an integer of 2 or
more.
##STR00030##
where R11, R12, R13, R14, R15 and R16 each represent a hydrogen
group, a halogen group, an alkyl group or a halogenated alkyl
group, and at least one of them is a halogen group or a halogenated
alkyl group.
##STR00031##
where R21, R22, R23 and R24 each represent a hydrogen group, a
halogen group, an alkyl group or a halogenated alkyl group, and at
least one of them is a halogen group or a halogenated alkyl
group.
[0129] The sulfone compound represented by Chemical Formula 35 has
a sulfonyl fluoride type structure in which a sulfonyl group
(--SO.sub.2--) and a fluorine group (--F) are bonded together. R11
to R16 in Chemical Formula 36 may be the same as or different from
one another. The same holds for R21 to R24 in Chemical Formula
37.
[0130] R1 in Chemical Formula 35 is a group having a carbon chain
or a carbon ring as a basic skeleton, and in the basic skeleton,
one kind or two or more kinds of elements selected from the group
consisting of hydrogen, oxygen and halogens may be included in any
form. The carbon chain may be a straight chain or a branched chain
having 1 or 2 or more side chains.
[0131] The above-described "form" means the number of elements, a
combination of elements and the like, and they are freely settable.
More specifically, as a form of hydrogen, for example, a part of an
alkylene group or an arylene group is cited. As a form of oxygen,
for example, an ether bond (--O--) or the like is cited. As a form
of halogens, for example, a part of a halogenated alkylene group or
the like is cited. The kind of halogen is not specifically limited,
but fluorine is preferable among halogens, because compared to
other halogens, the chemical stability of the electrolytic solution
is improved. In the above-described form of halogens, a halogen is
substituted for hydrogen in R1. In this case, the halogen may be
substituted for a part of hydrogen, or all of hydrogen. The forms
of hydrogen, oxygen and halogens may be any other form except for
the above-described forms.
[0132] As long as R1 has the above-described structure, R1 may be
any group. However, a sulfur atom in a number z of sulfonyl groups
is not bonded to an atom (for example, an oxygen atom) except for a
carbon atom in R1, and the sulfur atom is necessarily bonded to a
carbon atom.
[0133] R1 may be a derivative of a group obtained by the
above-described forms, and in this case, any other elements except
for hydrogen, oxygen and halogens may be included as a constituent
element. The "derivative" means a group obtained by introducing one
or two or more substituent groups into the above-described groups,
and the kinds of the substituent groups are freely settable.
[0134] Therefore, as long as the sulfone compound has a structure
corresponding to the structure shown in Chemical Formula 35, the
sulfone compound may have any structure as a whole.
[0135] Among them, as the sulfone compound, a compound represented
by Chemical Formula 38 is preferable. It is because in the case
where R2 is a straight-chain alkylene group or a halogenated
alkylene group, the number of carbon atoms is reduced, so compared
to the case where the number of carbon atoms is 3 or more, in the
electrolytic solution, high chemical stability is obtained, and
superior compatibility is obtained. The "halogenated alkylene
group" is a group obtained by substituting a halogen for at least a
part of hydrogen in an alkylene group.
##STR00032##
where R2 represents a z-valent group including carbon and one kind
or two or more kinds of elements selected from the group consisting
of hydrogen, oxygen and halogens, a sulfur atom in a sulfonyl group
is bonded to a carbon atom in R2, z is an integer of 2 or more, and
in the case where R2 is a straight-chain alkylene group or a
halogenated alkylene group, the number of carbon atoms is 2 or
less.
[0136] Moreover, as the sulfone compound, a compound represented by
Chemical Formula 39 is preferable, because the number z (the number
of sulfonyl fluoride parts) is reduced, so in the electrolytic
solution, high chemical stability is obtained, and superior
compatibility is obtained. The compound represented by Chemical
Formula 39 is a compound in which z in Chemical Formula 35 is z=2,
and R1 is a divalent group.
##STR00033##
where R3 represents a divalent group including carbon and one kind
or two or more kinds of elements selected from hydrogen, oxygen and
halogens, and a sulfur atom in a sulfonyl group is bonded to a
carbon atom in R3.
[0137] Examples of R3 which is a divalent group include a
straight-chain or branched alkylene group, an arylene group, a
group in which an arylene group and an alkylene group are bonded
together, a group in which an alkylene group and an ether bond are
bonded together, a halogenated group thereof and the like. A
"divalent group including an arylene group and an alkylene group"
may be a group in which one arylene group and one alkylene group
are bonded together, or a group in which two alkylene groups are
bonded through one arylene group. The "group in which an alkylene
group and an ether bond are bonded together" means a group in which
two alkylene groups are bonded through one ether bond. The
"halogenated group thereof" means a group obtained by substituting
a halogen for at least a part of hydrogen in the above-described
alkylene group or the like. The above-described number or the
bonding order of the alkylene groups, the arylene groups or the
ether bonds is freely settable. R3 may be any other group except
for the above-described groups.
[0138] In the case where R3 is a branched alkylene group, the
number of carbon atoms is freely settable. However, the number of
carbon atoms is preferably within a range from 2 to 10 both
inclusive, more preferably within a range from 2 to 6 both
inclusive, and more preferably within a range from 2 to 4 both
inclusive. In particular, in the case where R3 is a straight-chain
alkylene group or a halogenated alkylene group, the number of
carbon atoms is freely settable, but the number of atoms is
preferably 2 or less. Moreover, in the case where R3 is a group in
which an arylene group and an alkylene group are bonded together, a
group in which two alkylene groups are bonded through one arylene
group is preferable. The number of carbon atoms in this case is
freely settable, but the number of carbon atoms is preferably 8. It
is because in any of the cases, in the electrolytic solution, high
chemical stability is obtained, and superior compatibility is
obtained.
[0139] In the case where R3 is a group in which an alkylene group
and an ether bond are bonded together, the number of carbon atoms
is freely settable, but the number of carbon atoms is preferably
within a range from 2 to 12 both inclusive, and more preferably
within a range from 4 to 12 both inclusive. In this case, in
particular, R3 is preferably a group represented by
--CH.sub.2--CH.sub.2--(O--CH.sub.2--CH.sub.2).sub.n--, and n is
more preferably within a range from 1 to 3 both inclusive. It is
because in the electrolytic solution, high chemical stability is
obtained, and superior compatibility is obtained.
[0140] Specific examples of R3 include straight-chain alkylene
groups represented by Chemical Formulas 40(1) to 40(7), branched
alkylene groups represented by Chemical Formulas 41(1) to 41(9),
arylene groups represented by Chemical Formulas 42(1) to 42(3),
groups in which an arylene group and an alkylene group are bonded
together represented by Chemical Formulas 43(1) to 43(3), and
groups in which an alkylene group and an ether bond are bonded
together represented by Chemical Formulas 44(1) to 44(13). In
addition, as groups obtained by halogenating the above-described
groups, as shown in Chemical Formulas 45(1) to 45(9), groups
obtained by halogenating groups in which an alkylene group and an
ether bond are bonded together are cited. In addition to the groups
in which an alkylene group and an ether bond are bonded together,
any other alkylene group or the like may be halogenated.
##STR00034## ##STR00035## ##STR00036## ##STR00037##
##STR00038##
[0141] Specific examples of the compound represented by Chemical
Formula 35 include compounds represented by Chemical Formulas 46(1)
to 46(8). It is because in the electrolytic solution, high chemical
stability is obtained, and superior solubility is obtained. For
confirmation, R1 in Chemical Formula 35 is a straight-chain
alkylene group in Chemical Formulas 46(1) to 46(3), a
straight-chain fluorinated alkylene group in Chemical Formulas
46(4) to 46(6), an arylene group in Chemical Formula 46(7), and a
group obtained by halogenating a group in which an alkylene group
and an ether bond are bonded together in Chemical Formula
46(8).
##STR00039##
[0142] Only one kind or a mixture of a plurality of kinds selected
from the compounds described as the compound represented by
Chemical Formula 35 may be used. As long as the compound has a
structure shown in Chemical Formula 35, the compound is not limited
to the compounds represented by Chemical Formulas 38, 39 and
46.
[0143] The content of the sulfone compound represented by Chemical
Formula 35 in the solvent is freely settable. However, the content
is preferably within a range from 0.01 wt % to 10 wt % both
inclusive. It is because in the electrolytic solution, high
chemical stability is obtained. More specifically, when the content
is smaller than 0.01 wt %, there is a possibility that
electrochemical stability is not obtained sufficiently and stably,
and when the content is larger than 10 wt %, there is a possibility
that main electrical performance of an electrochemical device (for
example, capacity characteristics or the like in a secondary
battery) is not obtained sufficiently.
[0144] The halogenated carbonates represented by Chemical Formulas
36 and 37 are decomposed during the operation of the
electrochemical device (during electrode reaction), and a
halogen-based film is formed on an electrode. Thereby, the
decomposition reaction of the electrolytic solution is
prevented.
[0145] The "halogenated alkyl group" which describes R11 to R16 or
R21 to R24 means a group obtained by substituting a halogen for at
least a part of hydrogen in an alkyl group. The kind of the halogen
is not specifically limited. However, at least one kind selected
from the group consisting of fluorine, chlorine and bromine is
cited, and among them, fluorine is preferable, because a high
effect is obtained. Any other halogen may be used.
[0146] In particular, as the halogenated carbonate, a compound
including two halogens (a dihalogenated carbonate) is preferable to
a compound including one halogen (a monohalogenated carbonate),
because a capability to form a film is improved, and a stronger and
more stable film is formed, so the decomposition reaction of the
electrolytic solution is further prevented.
[0147] Examples of the chain carbonate represented by Chemical
Formula 36 which includes a halogen include fluoromethyl methyl
carbonate, bis(fluoromethyl) carbonate, difluoromethyl methyl
carbonate and the like. Only one kind or a mixture of a plurality
of kinds selected from them may be used.
[0148] In the case where at least one of R21 to R24 in Chemical
Formula 37 is an alkyl group or a halogenated alkyl group, a methyl
group, an ethyl group, a halogenated methyl group or a halogenated
ethyl group is preferable, because a high effect is obtained.
[0149] Examples of the cyclic carbonate represented by Chemical
Formula 37 which includes a halogen include compounds represented
by Chemical Formulas 47 and 48. More specifically,
4-fluoro-1,3-dioxolane-2-one in Chemical Formula 47(1),
4-chloro-1,3-dioxolane-2-one in Chemical Formula 47(2),
4,5-difluoro-1,3-dioxolane-2-one in Chemical Formula 47(3),
tetrafluoro-1,3-dioxolane-2-one in Chemical Formula 47(4),
4-fluoro-5-chloro-1,3-dioxolane-2-one in Chemical Formula 47(5),
4,5-dichloro-1,3-dioxolane-2-one in Chemical Formula 47(6),
tetrachloro-1,3-dioxolane-2-one in Chemical Formula 47(7),
4,5-bistrifluoromethyl-1,3-dioxolane-2-one in Chemical Formula
47(8), 4-trifluoromethyl-1,3-dioxolane-2-one in Chemical Formula
47(9), 4,5-difluoro-4,5-dimethyl-1,3-dioxolane-2-one in Chemical
Formula 47(10), 4-methyl-5,5-difluoro-1,3-dioxolane-2-one in
Chemical Formula 47(11), 4-ethyl-5,5-difluoro-1,3-dioxolane-2-one
in Chemical Formula 47(12) and the like are cited. Moreover,
4-trifluoromethyl-5-fluoro-1,3-dioxolane-2-one in Chemical Formula
48(1), 4-trifluoromethyl-5-methyl-1,3-dioxolane-2-one in Chemical
Formula 48(2), 4-fluoro-4,5-dimethyl-1,3-dioxolane-2-one in
Chemical Formula 48(3),
4,4-difluoro-5-(1,1-difluoroethyl)-1,3-dioxolane-2-one in Chemical
Formula 48(4), 4,5-dichloro-4,5-dimethyl-1,3-dioxolane-2-one in
Chemical Formula 48(5), 4-ethyl-5-fluoro-1,3-dioxolane-2-one in
Chemical Formula 48(6), 4-ethyl-4,5-difluoro-1,3-dioxolane-2-one in
Chemical Formula 48(7), 4-ethyl-4,5,5-trifluoro-1,3-dioxolane-2-one
in Chemical Formula 48(8), 4-fluoro-4-methyl-1,3-dioxolane-2-one in
Chemical Formula 48(9) and the like are cited. Only one kind or a
mixture of a plurality of kinds selected from them may be used.
##STR00040## ##STR00041## ##STR00042## ##STR00043##
[0150] Among the above-described halogenated carbonates, as the
monohalogenated carbonate, fluoromethyl methyl carbonate or
4-fluoro-1,-3-dioxolane-2-one is preferable, and as a dihalogenated
carbonate, bis(fluoromethyl) carbonate or
4,5-difluoro-1,3-dioxolane-2-one is preferable. In particular, as
4,5-difluoro-1,3-dioxolane-2-one, a trans-isomer is preferable to a
cis-isomer, because it is easily available, and a high effect is
obtained.
[0151] The solvent preferably includes one kind or two or more
kinds of nonaqueous solvents such as other organic solvents
together with the above-described sulfone compound and the
above-described halogenated carbonates. The kind, content and the
like of the nonaqueous solvent are the same as those in the first
embodiment.
[0152] Moreover, the solvent may include a sultone (cyclic
sulfonate) or an acid anhydride. It is because the chemical
stability of the electrolytic solution is further improved. The
kinds and contents of the sultone and acid anhydride are the same
as those in the first embodiment.
[0153] The intrinsic viscosity of the solvent is preferably 10.0
mPas or less at 25.degree. C. It is because the dissociation
property of the electrolyte salt and ion mobility are improved. The
intrinsic viscosity in a state in which the electrolyte salt is
dissolved in the solvent (that is, the intrinsic viscosity of the
electrolytic solution) is also preferably 10.0 mPas or less at
25.degree. C. because of the same reason.
[0154] The electrolyte salt includes one kind or two or more kinds
of light metal salts such as a lithium salt. The kind, the content
and the like of the lithium salt are the same as those in the first
embodiment.
[0155] In the electrolytic solution according to the embodiment,
the solvent includes the sulfone compound (the sulfone compound
represented by Chemical Formula 35) and the halogenated carbonate
(at least one kind selected from the group consisting of the chain
carbonate represented by Chemical Formula 36 which includes a
halogen and the cyclic carbonate represented by Chemical Formula 37
which includes a halogen), so compared to the case where neither of
them is included, or only one of them is included, the chemical
stability is improved. Therefore, the decomposition reaction in the
case where the electrolytic solution is used in an electrochemical
device such as a secondary battery is prevented, so the
electrolytic solution is capable of contributing to an improvement
in characteristics such as cycle characteristics, storage
characteristics and swelling characteristics. In this case, when
the sulfone compound is the compound represented by Chemical
Formula 38 or 39, and the content of the sulfone compound in the
solvent is within a range from 0.01 wt % to 10 wt % both inclusive,
a high effect is able to be obtained. In particular, when the
dihalogenated carbonate rather than the monohalogenated carbonate
is included as the halogenated carbonate, a higher effect is able
to be obtained. Other effects relating to the electrolytic solution
are the same as those in the first embodiment.
[0156] The electrolytic solution according to the embodiment is
applicable to the first to fourth secondary batteries described in
the first embodiment. The configurations of the first to the fourth
secondary batteries are the same as those in the first embodiment,
except for the kind of the electrolytic solution is different.
[0157] In the first to the fourth secondary batteries, in the case
where the capacity of the anode is represented on the basis of
insertion and extraction of lithium, the electrolytic solution
according to the embodiment is included, so the decomposition
reaction of the electrolytic solution is prevented. Therefore,
battery characteristics such as cycle characteristics, storage
characteristics and swelling characteristics are able to be
improved. In particular, when the anode active material of the
anode includes a material being capable of inserting and extracting
lithium and including at least one kind selected from the group
consisting of metal elements and metalloid elements as a
constituent element, the electrolytic solution is decomposed more
easily, so a higher effect than that in the case where a carbon
material is included is able to be obtained. Other effects relating
to the secondary batteries are the same as those in the case where
the above-described electrolytic solution is described.
Third Embodiment
[0158] An electrolytic solution according to a third embodiment is
used in an electrochemical device such as a secondary battery as in
the case of the first embodiment, and includes a solvent and an
electrolyte salt dissolved in the solvent.
[0159] The solvent includes one kind or two or more kinds of
sulfone compounds represented by Chemical Formula 49. It is because
the chemical stability of the electrolytic solution is improved.
The sulfone compound represented by Chemical Formula 49 has a
sulfonyl fluoride type structure in which a sulfonyl group
(--SO.sub.2--) and a fluorine group (--F) are bonded together.
##STR00044##
where R1 represents a chain group including a carbon-carbon
unsaturated bond, or a derivative thereof.
[0160] R1 in Chemical Formula 49 is a group having a carbon chain
which includes a carbon-carbon unsaturated bond (a carbon-carbon
double bond or a carbon-carbon triple bond) as a basic skeleton. In
R1, the number of carbon-carbon unsaturated bonds may be 1 or 2 or
more. Moreover, the carbon-carbon unsaturated bond may be included
at an end of the group or in the middle of the group. As long as R1
is a chain group, the chain group may be a straight chain or a
branched chain having 1 or 2 or more side chains.
[0161] The number of carbon atoms in R1 is not specifically
limited. However, the number of carbon atoms is preferably 4 or
less. It is because compared to the case where the number of carbon
atoms is 5 or more, superior compatibility is obtained.
[0162] For example, R1 is a group including carbon and one kind or
two or more kind of elements selected from the group consisting of
hydrogen, oxygen and halogens as constituent elements, and in RE an
element such as hydrogen may be included in any form. The "form"
means the number of elements, a combination of elements and the
like.
[0163] More specifically, as a form of hydrogen, for example, a
part of an alkyl group such as a methyl group (--CH.sub.3), a part
of an alkylene group such as an ethylene group (--CH.sub.2--), a
part of a carbon-carbon double bond such as a vinyl group
(--CH.dbd.CH.sub.2), a part of a carbon-carbon triple bond such as
a ethynyl group (--C.ident.CH) or the like is cited.
[0164] As a form of oxygen, for example, an ether bond (--O--), a
part of a carbonyl group (--CO--) or the like is cited. In RE the
ether bond may be included at an end or in the middle.
[0165] As a form of halogens (in this case, halogens are
represented by X), for example, a part of a halogenated alkyl group
such as a halogenated methyl group (--CX.sub.3), a part of a
halogenated alkylene group such as a halogenated ethylene group
(--CX.sub.2--), a part of a halogenated carbon-carbon double bond
such as a halogenated vinyl group (--CX.dbd.CX.sub.2), a part of a
halogenated carbon-carbon triple bond such as a halogenated ethynyl
group (--C.ident.CX) or the like is cited. The kind of halogen is
not specifically limited, but fluorine is preferable. It is because
compared to other halogens, the chemical stability of the
electrolytic solution is improved.
[0166] In the above-described form of halogens, a halogen is
substituted for hydrogen in R1. In this case, the halogen may be
substituted for a part of hydrogen, or all of hydrogen.
[0167] R1 may be a derivative of a group obtained by the
above-described form, and in this case, any other elements except
for hydrogen, oxygen and halogens may be included as a constituent
element. The "derivative" means a group obtained by introducing one
or two or more substituent groups into the above-described groups.
The kind of the substituent group is not specifically limited.
However, for example, a group (--SO.sub.2F) having the same
structure as that of a part except for R1 in Chemical Formula 49,
or the like is cited.
[0168] Only one kind or a combination of a plurality of kinds
selected from the above-described forms may be included in R1. The
number of each of the forms in this case may be 1 or 2 or more.
When R1 is a chain group including a carbon-carbon unsaturated bond
or a derivative thereof, hydrogen, oxygen and halogens in any other
forms except for the above-described forms may be included in
R1.
[0169] Examples of the sulfone compound represented by Chemical
Formula 49 include compounds represented by Chemical Formulas 50(1)
to 50(9), Chemical Formulas 51(1) to 51(8) and Chemical Formulas
52(1) to 52(8). Among them, the compound represented by Chemical
Formula 50(1), 50(7), 51(6) or 52(1) is preferable. It is because
high chemical stability is obtained in the electrolytic solution.
As long as the sulfone compound has a structure shown in Chemical
Formula 49, the sulfone compound is not limited to the compounds
represented by Chemical Formulas 50 to 52.
##STR00045## ##STR00046## ##STR00047##
[0170] The content of the sulfone compound represented by Chemical
Formula 49 in the solvent is freely settable, but is preferably
within a range from 0.01 wt % to 5 wt % both inclusive. It is
because high chemical stability is obtained in the electrolytic
solution. More specifically, when the content is smaller than 0.01
wt %, there is a possibility that the chemical stability of the
electrolytic solution is not obtained sufficiently and stably, and
when the content is larger than 5 wt %, there is a possibility that
main electrical performance of an electrochemical device (for
example, capacity characteristics or the like in a secondary
battery) is not obtained sufficiently.
[0171] The solvent preferably includes one kind or two or more
kinds of nonaqueous solvents such as other organic solvents
together with the sulfone compound represented by Chemical Formula
49. The kind, the content and the like of the nonaqueous solvent
are the same as those in the first embodiment.
[0172] Moreover, the solvent may include a sultone (a cyclic
sulfonate) or an acid anhydride, because the chemical stability of
the electrolytic solution is further improved. For example, the
kinds, the contents and the like of the sultone and the acid
anhydride are the same as those in the first embodiment.
[0173] The intrinsic viscosity of the solvent is preferably 10.0
mPas or less at 25.degree. C. It is because the dissociation
property of the electrolyte salt and ion mobility are improved. The
intrinsic viscosity in a state in which the electrolyte salt is
dissolved in the solvent (that is, the intrinsic viscosity of the
electrolytic solution) is also preferably 10.0 mPas or less at
25.degree. C. because of the same reason.
[0174] The electrolyte salt includes, for example, one kind or two
or more kinds of light metal salts such as a lithium salt. The
kind, the content and the like of the lithium salt are the same as
those in the first embodiment.
[0175] In the electrolytic solution according to the embodiment,
the solvent includes the sulfone compound represented by Chemical
Formula 49, so compared to the case where the sulfone compound is
not included, or the case where other sulfone compounds represented
by Chemical Formulas 53, 54 and 55 are included, the chemical
stability is improved. The other sulfone compounds represented by
Chemical Formulas 53 and 55 are compounds in which R1 in Chemical
Formula 49 is a chain group not including a carbon-carbon
unsaturated bond, and the other sulfone compound represented by
Chemical Formula 54 is a compound in which R1 is a cyclic group
including a carbon-carbon unsaturated bond. Therefore, in the case
where the electrolytic solution is used in an electrochemical
device, the decomposition reaction is prevented, the electrolytic
solution is capable of contributing to an improvement in cycle
characteristics. In this case, when the content of the sulfone
compound represented by Chemical Formula 49 in the solvent is
within a range from 0.01 wt % to 5 wt % both inclusive, a high
effect is able to be obtained. Other effects relating to the
electrolytic solution are the same as those in the first
embodiment.
##STR00048##
[0176] The electrolytic solution according to the embodiment is
applicable to, for example, the first to the fourth secondary
batteries described in the first embodiment. The configurations of
the first to the fourth secondary batteries are the same as those
in the first embodiment, except that the kind of the electrolytic
solution is different.
[0177] In the first to the fourth secondary batteries, in the case
where the capacity of the anode is represented on the basis of
insertion and extraction of lithium, the electrolytic solution
according to the embodiment is included, so the decomposition
reaction of the electrolytic solution is prevented. Therefore, even
if charge and discharge are repeated, a discharge capacity is less
prone to being reduced, so cycle characteristics are able to be
improved. In particular, when the anode active material of the
anode includes a material being capable of inserting and extracting
lithium, and including at least one kind selected from the group
consisting of metal elements and metalloid elements as a
constituent element, the electrolytic solution is decomposed more
easily, so a higher effect than that in the case where a carbon
material is included is obtained. Other effects relating to the
secondary batteries are the same as those in the case where the
above-described electrolytic solution is described.
EXAMPLES
[0178] Specific examples will be described in detail below.
[0179] At first, examples of the electrolytic solution and the
secondary battery according to the first embodiment will be
described below.
Example 1-1
[0180] A laminate film type secondary battery shown in FIGS. 3 and
4 was formed using artificial graphite as an anode active material.
At that time, the secondary battery was a lithium-ion secondary
battery in which the capacity of the anode 34 was represented on
the basis of insertion and extraction of lithium.
[0181] At first, the cathode 33 was formed. After lithium carbonate
(Li.sub.2CO.sub.3) and cobalt carbonate (CoCO.sub.3) were mixed at
a molar ratio of 0.5:1 to form a mixture, the mixture was fired in
air at 900.degree. C. for 5 hours to obtain a lithium-cobalt
complex oxide (LiCoO.sub.2). Next, after 91 parts by weight of the
lithium-cobalt complex oxide as a cathode active material, 6 parts
by weight of graphite as an electrical conductor and 3 parts by
weight of polyvinylidene fluoride as a binder were mixed to form a
cathode mixture, the cathode mixture was dispersed in
N-methyl-2-pyrrolidone to form paste-form cathode mixture slurry.
Finally, after the cathode mixture slurry was uniformly applied to
both sides of the cathode current collector 33A made of
strip-shaped aluminum foil (with a thickness of 20 .mu.m), and was
dried, the cathode mixture slurry was compression molded by a
roller press to form the cathode active material layer 33B.
[0182] Next, the anode 34 was formed. At first, after 90 parts by
weight of artificial graphite as an anode active material and 10
parts by weight of polyvinylidene fluoride as a binder were mixed
to form an anode mixture, the anode mixture was dispersed in
N-methyl-2-pyrrolidone to form paste-form anode mixture slurry.
Finally, after the anode mixture slurry was uniformly applied to
both sides of the anode current collector 34A made of strip-shaped
copper foil (with a thickness of 15 .mu.m), and was dried, the
anode mixture slurry was compression molded by a roller press to
form the anode active material layer 34B.
[0183] Next, the electrolytic solution was prepared. At first,
after ethylene carbonate (EC) and diethyl carbonate (DEC) were
mixed at a weight ratio of EC:DEC=30:70 to form a mixture, the
compound represented by Chemical Formula 19(2) as the sulfone
compound represented by Chemical Formula 11 (the compound
represented by Chemical Formula 12) was added to and mixed with the
mixture to form a solvent. At that time, the content of the
compound represented by Chemical Formula 19(2) in the solvent was
0.01 wt %. The "wt %" is a unit in the case where the whole solvent
was 100 wt %, and the same holds for the following examples.
Finally, as the electrolyte salt, lithium hexafluorophosphate
(LiPF.sub.6) was dissolved in the solvent. At that time, the
concentration of the electrolyte salt in the electrolytic solution
was 1 mol/kg.
[0184] Next, a secondary battery was assembled using the cathode 33
and the anode 34. At first, the cathode lead 31 made of aluminum
was welded to an end of the cathode current collector 33A, and the
anode lead 32 made of nickel was welded to an end of the anode
current collector 34A. Next, after the cathode 33, the separator 35
(with a thickness of 25 .mu.m) made of a microporous polypropylene
film and the anode 34 were laminated in this order to form a
laminate, and then the laminate was spirally wound several times in
a longitudinal direction, an outermost portion of the spirally
wound laminate was fixed by the protective tape 37 made of an
adhesive tape so as to form a spirally wound body as a precursor
body of the spirally wound electrode body 30. Next, after the
spirally wound body was sandwiched between the package members 40
made of a laminate film (with a total thickness of 100 .mu.m) with
a three-layer configuration formed by laminating a nylon film (with
a thickness of 30 .mu.m), aluminum foil (with a thickness of 40
.mu.m) and a cast polypropylene film (with a thickness of 30 .mu.m)
in order from outside, the edge portions of the package members 40
except for edge portions on one side were adhered by thermal fusion
bonding to form a pouched package, thereby the spirally wound body
was contained in the package members 40. Next, the electrolytic
solution was injected into the package members 40 from an opened
portion of the package members 40, and the separator 35 was
impregnated with the electrolytic solution, thereby the spirally
wound electrode body 30 was formed. Finally, the opened portion of
the package members 40 were sealed by thermal fusion bonding in a
vacuum atmosphere, thereby the laminate film type secondary battery
was completed.
Examples 1-2 to 1-5
[0185] Secondary batteries were formed by the same steps as those
in Example 1-1, except that the content of the compound represented
by Chemical Formula 19(2) in the solvent was 1 wt % (Example 1-2),
2 wt % (Example 1-3), 5 wt % (Example 1-4), or 10 wt % (Example
1-5).
Examples 1-6 to 1-9
[0186] Secondary batteries were formed by the same steps as those
in Example 1-2, except that instead of the compound represented by
Chemical Formula 19(2), the compound represented by Chemical
Formula 19(1) (Example 1-6), the compound represented by Chemical
Formula 19(3) (Example 1-7), the compound represented by Chemical
Formula 19(4) (Example 1-8) or the compound represented by Chemical
Formula 19(5) (Example 1-9) was used.
Comparative Example 1-1
[0187] A secondary battery was formed by the same steps as those in
Example 1-1, except that the compound represented by Chemical
Formula 19(2) was not added.
Comparative Example 1-2
[0188] A secondary battery was formed by the same steps as those in
Example 1-2, except that instead of the sulfone compound
represented by Chemical Formula 11, another sulfone compound
represented by Chemical Formula 34 was used.
[0189] When the cycle characteristics and the storage
characteristics of the secondary batteries of Examples 1-1 to 1-9
and Comparative Examples 1-1 and 1-2 were determined, results shown
in Table 1 were obtained.
[0190] To determine the cycle characteristics, two cycles of charge
and discharge were performed on each of the secondary batteries in
an atmosphere at 23.degree. C. to determine the discharge capacity
in the second cycle, and then the cycle of charge and discharge was
repeated until the total cycle number reached 100 cycles in the
same atmosphere to determine the discharge capacity in the 100th
cycle. Then, a room-temperature cycle discharge capacity retention
ratio (%)=(discharge capacity in the 100th cycle/discharge capacity
in the second cycle).times.100 was determined by calculation. As
the conditions of one cycle of charge and discharge, after each of
the secondary batteries was charged at a constant current of 0.2 C
and a constant voltage until reaching an upper limit voltage of 4.2
V, each of the secondary batteries was discharged at a constant
current of 0.2 C until reaching a cutoff voltage of 2.7 V. In
addition "0.2 C" represents a current value at which the
theoretical capacity of a battery is fully discharged for 5
hours.
[0191] To determine the storage characteristics, two cycles of
charge and discharge were performed on each of the secondary
batteries to determine the discharge capacity, and then after each
of the secondary batteries which was charged again was stored for
10 days in a constant temperature bath at 80.degree. C., each of
the secondary batteries was discharged in an atmosphere at
23.degree. C. to determine the discharge capacity. Then, a
high-temperature storage discharge capacity retention ratio
(%)=(discharge capacity after storing/discharge capacity before
storing).times.100 was determined by calculation. The conditions of
one cycle of charge and discharge were the same as those in the
case where the cycle characteristics were determined.
[0192] In addition, in the following examples and the following
comparative examples, the steps and the conditions when determining
the cycle characteristics and the storage characteristics were the
same as those described above.
TABLE-US-00001 TABLE 1 Anode active material: artificial graphite
ROOM-TEMPERATURE HIGH-TEMPERATURE CYCLE DISCHARGE STORAGE DISCHARGE
SOLVENT CAPACITY RETENTION CAPACITY ELECTROLYTE SULFONE COMPOUND
RATIO RETENTION RATIO SALT KIND KIND WT % (%) (%) EXAMPLE 1-1
LiPF.sub.6 EC + DEC CHEMICAL 0.01 82 87 EXAMPLE 1-2 1 mol/kg
FORMULA 19(2) 1 84 90 EXAMPLE 1-3 2 85 90 EXAMPLE 1-4 5 84 88
EXAMPLE 1-5 10 82 86 EXAMPLE 1-6 CHEMICAL 1 86 90 FORMULA 19(1)
EXAMPLE 1-7 CHEMICAL 1 85 87 FORMULA 19(3) EXAMPLE 1-8 CHEMICAL 1
83 88 FORMULA 19(4) EXAMPLE 1-9 CHEMICAL 1 83 90 FORMULA 19(5)
COMPARATIVE LiPF.sub.6 EC + DEC -- -- 80 84 EXAMPLE 1-1 1 mol/kg
COMPARATIVE CHEMICAL 1 81 84 EXAMPLE 1-2 FORMULA 34
[0193] As shown in Table 1, in Examples 1-1 to 1-9 in which the
solvent included the sulfone compound represented by Chemical
Formula 11 (the compound represented by Chemical Formula 19(1),
19(2), 19(3), 19(4) or 19(5)), a higher room-temperature cycle
discharge capacity retention ratio and a higher high-temperature
storage discharge capacity retention ratio than those in
Comparative Examples 1-1 and 1-2 in which the sulfone compound
represented by Chemical Formula 11 was not included were
obtained.
[0194] More specifically, in Examples 1-1 to 1-5 in which the
solvent included the compound represented by Chemical Formula
19(2), compared to Comparative Example 1-1 in which the solvent did
not include the compound, the room-temperature cycle discharge
capacity retention ratio and the high-temperature storage discharge
capacity retention ratio were higher. In this case, when the
content of the compound represented by Chemical Formula 19(2) in
the solvent was within a range from 0.01 wt % to 10 wt % both
inclusive, a high room-temperature cycle discharge capacity
retention ratio and a high high-temperature storage discharge
capacity retention ratio were obtained. When the content of the
compound represented by Chemical Formula 19(2) was smaller than
0.01 wt % or larger than 10 wt %, the room-temperature cycle
discharge capacity retention ratio and the high-temperature storage
discharge capacity retention ratio were greatly reduced, and when
the content was larger than 10 wt %, the capacity showed a tendency
to be greatly reduced.
[0195] Moreover, in Examples 1-6 to 1-9 in which the solvent
included the compound represented by Chemical Formula 19(1) or the
like, compared to Comparative Example 1-1 in which the compound
represented by Chemical Formula 19(1) or the like was not included,
the room-temperature cycle discharge capacity retention ratio and
the high-temperature storage discharge capacity retention ratio
were higher, and a room-temperature cycle discharge capacity
retention ratio and a high-temperature storage discharge capacity
retention ratio which were substantially equal to those in Example
1-2 in which the compound represented by Chemical Formula 19(2) was
included were obtained.
[0196] In particular, when Examples 1-2 and 1-6 in which the
sulfone compound represented by Chemical Formula 11 (the compound
represented by Chemical Formulas 19(1) or 19(2)) was included and
Comparative Example 1-2 in which another sulfone compound
represented by Chemical Formula 34 was included were compared with
reference to the room-temperature cycle discharge capacity
retention ratio and the high-temperature storage discharge capacity
retention ratio in Comparative Example 1-1, the room-temperature
cycle discharge capacity retention ratio and the high-temperature
storage discharge capacity retention ratio were increased only
slightly in Comparative Example 1-2. However, they were greatly
increased in Examples 1-2 and 1-6. The result showed that the
sulfone compound represented by Chemical Formula 11 and the sulfone
compound represented by Chemical Formula 34 had a commonality in
that R1 in Chemical Formula 11 was a straight-chain alkylene group.
However, to increase the room-temperature cycle discharge capacity
retention ratio and the high-temperature storage discharge capacity
retention ratio, Examples 1-2 and 1-6 (the number of carbon atoms
was 2 or less) had an overwhelming advantage over Comparative
Example 1-2 (the number of carbon atoms was 3). This tendency was
the same in the case where R1 was a straight-chain halogenated
alkylene group.
[0197] Therefore, it was confirmed that in the secondary battery
according to the embodiment, in the case where the anode 34
included artificial graphite as the anode active material, when the
solvent of the electrolytic solution included the sulfone compound
represented by Chemical Formula 11, the cycle characteristics and
the storage characteristics were improved. Moreover, it was
confirmed that in the case where R1 in Chemical Formula 11 was a
straight-chain alkylene group or a halogenated alkylene group, the
number of carbon atoms was 2 or less, so superior characteristics
were obtained. In this case, it was confirmed that when the content
of the compound represented by Chemical Formula 11 in the solvent
was within a range from 0.01 wt % to 10 wt % both inclusive,
superior characteristics were obtained, and when the content was
within a range from 1 wt % to 5 wt % both inclusive, the
characteristics were further improved.
Example 2-1
[0198] A secondary battery was formed by the same steps as those in
Example 1-2, except that as the solvent, propylene carbonate (PC)
was added. At that time, the mixture ratio of EC, DEC and PC was a
weight ratio of 20:60:20.
Examples 2-2 and 2-3
[0199] Secondary batteries were formed by the same steps as those
in Example 1-2, except that as the solvent, instead of DEC, ethyl
methyl carbonate (EMC: Example 2-2) or dimethyl carbonate (DMC:
Example 2-3) was used.
Examples 2-4 to 2-10
[0200] Secondary batteries were formed by the same steps as those
in Example 1-2, except that as the solvent, vinylene carbonate (VC:
Example 2-4) as the cyclic carbonate including an unsaturated bond,
4-fluoro-1,3-dioxolane-2-one (FEC: Example 2-5) as the cyclic
carbonate represented by Chemical Formula 21 which included a
halogen, trans-4,5-difluoro-1,3-dioxolane-2-one (t-DFEC: Example
2-6), cis-4,5-difluoro-1,3-dioxolane-2-one (c-DFEC: Example 2-7),
bis(fluoromethyl) carbonate (BFDMC: Example 2-8) as the chain
carbonate represented by Chemical Formula 20 which included a
halogen, propene sultone (PRS: Example 2-9) as the sultone, or
sulfobenzoid anhydride (SBAH: Example 2-10) as the acid anhydride
was added. At that time, the content of VC or the like in the
solvent was 1 wt %.
Comparative Examples 2-1 and 2-2
[0201] Secondary batteries were formed by the same steps as those
in Examples 2-5 and 2-6, except that the compound represented by
Chemical Formula 19(2) was not added.
[0202] When the cycle characteristics and the storage
characteristics of the secondary batteries of Examples 2-1 to 2-10
and Comparative Examples 2-1 and 2-2 were determined, results shown
in Table 2 were obtained.
TABLE-US-00002 TABLE 2 Anode active material: artificial graphite
HIGH- TEMPERATURE ROOM-TEMPERATURE STORAGE SOLVENT CYCLE DISCHARGE
DISCHARGE SULFONE CAPACITY RETENTION CAPACITY ELECTROLYTE COMPOUND
RATIO RETENTION RATIO SALT KIND KIND WT % (%) (%) EXAMPLE 1-2
LiPF.sub.6 EC + DEC CHEMICAL 1 84 90 EXAMPLE 2-1 1 mol/kg EC + DEC
+ PC FORMULA 85 92 EXAMPLE 2-2 EC + EMC 19(2) 83 91 EXAMPLE 2-3 EC
+ DMC 86 91 EXAMPLE 2-4 EC + VC 87 90 EXAMPLE 2-5 DEC FEC 88 86
EXAMPLE 2-6 t-DFEC 89 91 EXAMPLE 2-7 c-DFEC 90 90 EXAMPLE 2-8 BFDMC
88 91 EXAMPLE 2-9 PRS 86 92 EXAMPLE 2-10 SBAH 86 94 COMPARATIVE
LiPF.sub.6 EC + -- -- -- 80 84 EXAMPLE 1-1 1 mol/kg DEC COMPARATIVE
FEC 84 85 EXAMPLE 2-1 COMPARATIVE t-DFEC 85 85 EXAMPLE 2-2
[0203] As shown in Table 2, in Examples 2-1 to 2-3 in which the
solvent included the compound represented by Chemical Formula 19(2)
and PC or the like, the room-temperature cycle discharge capacity
retention ratio and the high-temperature storage discharge capacity
retention ratio were higher than those in Comparative Example 1-1
in which the compound represented by Chemical Formula 19(2) was not
included, and a room-temperature cycle discharge capacity retention
ratio and a high-temperature storage discharge capacity retention
ratio which were substantially equal to those in Example 1-2 in
which PC or the like was not included were obtained.
[0204] Moreover, in Examples 2-4 to 2-10 in which the solvent
included VC or the like, the room-temperature cycle discharge
capacity retention ratio was higher than that in Example 1-2 in
which VC or the like was not included, and the high-temperature
storage capacity retention ratio was equal to or higher than that
in Example 1-2. In this case, when FEC, t-DFEC and c-DFEC were
compared, there was a tendency that in the case where t-DFEC or the
like as a dihalogenated carbonate was included, the
room-temperature cycle discharge capacity retention ratio and the
high-temperature storage discharge capacity retention ratio were
higher than those in the case where FEC as a monohalogenated
carbonate was included. In Examples 2-5 and 2-6 in which the
solvent included the compound represented by Chemical Formula
19(2), the room-temperature cycle discharge capacity retention
ratio and the high-temperature storage discharge capacity retention
ratio were higher than those in Comparative Examples 2-1 and 2-2 in
which the compound represented by Chemical Formula 19(2) was not
included.
[0205] Therefore, it was confirmed that in the secondary battery
according to the embodiment, even if the composition of the solvent
was changed, the cycle characteristics and the storage
characteristics were improved. It was confirmed that in this case,
even in the case where propylene carbonate or the like was added to
the solvent, high characteristics were obtained, and when the
cyclic carbonate including an unsaturated bond, at least one kind
selected from the group consisting of the chain carbonate
represented by Chemical Formula 20 which included a halogen and the
cyclic carbonate represented by Chemical Formula 21 which included
a halogen, the sultone or the acid anhydride was added to the
solvent, the characteristics were further improved.
Examples 3-1 to 3-3
[0206] Secondary batteries were formed by the same steps as those
in Example 1-2, except that as the electrolyte salt, lithium
tetrafluoroborate (LiBF.sub.4: Example 3-1), the compound
represented by Chemical Formula 27(6) as the compound represented
by Chemical Formula 24 (Example 3-2), or the compound represented
by Chemical Formula 28(6) as the compound represented by Chemical
Formula 25 (Example 3-3) was added. At that time, the concentration
of lithium hexafluorophosphate in the electrolytic solution was 0.9
mol/kg, and the concentration of lithium tetrafluoroborate or the
like was 0.1 mol/kg.
[0207] When the cycle characteristics and the storage
characteristics of the secondary batteries of Examples 3-1 to 3-3
were determined, results shown in Table 3 were obtained.
TABLE-US-00003 TABLE 3 Anode active material: artificial graphite
ROOM-TEMPERATURE HIGH-TEMPERATURE SOLVENT CYCLE DISCHARGE STORAGE
DISCHARGE SULFONE CAPACITY RETENTION CAPACITY COMPOUND RATIO
RETENTION RATIO ELECTROLYTE SALT KIND KIND WT % (%) (%) EXAMPLE 1-2
LiPF.sub.6 EC + CHEMICAL 1 84 90 1 mol/kg DEC FORMULA EXAMPLE 3-1
LiPF.sub.6 LiBF.sub.4 19(2) 86 92 0.9 mol/kg 0.1 mol/kg EXAMPLE 3-2
LiPF.sub.6 CHEMICAL 88 92 0.9 mol/kg FORMULA 27(6) 0.1 mol/kg
EXAMPLE 3-3 LiPF.sub.6 CHEMICAL 86 91 0.9 mol/kg FORMULA 28(6) 0.1
mol/kg
[0208] As shown in Table 3, in Examples 3-1 to 3-3 in which the
electrolyte salt included lithium tetrafluoroborate or the like,
the room-temperature cycle discharge capacity retention ratio and
the high-temperature storage discharge capacity retention ratio
were higher than those in Example 1-2 in which lithium
tetrafluoroborate or the like was not included.
[0209] Therefore, it was confirmed that in the secondary battery
according to the embodiment, even if the kind of the electrolyte
salt was changed, the cycle characteristics and the storage
characteristics were improved. It was confirmed that in this case,
when the electrolyte salt included lithium tetrafluoroborate, the
compound represented by Chemical Formula 24, or the compound
represented by Chemical Formula 25, characteristics were further
improved.
[0210] The result in the case where the electrolyte salt includes
at least one kind selected from the group consisting of lithium
perchlorate and lithium hexafluoroarsenate, the compound
represented by Chemical Formula 26, or at least one kind selected
from the group consisting of the compounds represented by Chemical
Formulas 30 to 32 is not shown here. However, lithium perchlorate
or the like has the same functions as lithium tetrafluoroborate, so
it is obvious that even in the case where lithium perchlorate or
the like is included, the same effects are obtained. The same holds
for the case where two or more electrolyte salts of the same kind
or different kinds are mixed.
Examples 4-1 to 4-5
[0211] Secondary batteries were formed by the same steps as those
in Examples 1-1 to 1-5, except that as the anode active material,
instead of artificial graphite, silicon was used to form the anode
active material layer 34B. In the case where the anode active
material layer 34B was formed, silicon was deposited on the anode
current collector 34A by an electron beam evaporation method.
Examples 4-6 to 4-9
[0212] Secondary batteries were formed by the same steps as those
in Example 4-3, except that instead of the compound represented by
Chemical Formula 19(2), the compound represented by Chemical
Formula 19(1) (Example 4-6), the compound represented by Chemical
Formula 19(3) (Example 4-7), the compound represented by Chemical
Formula 19(4) (Example 4-8), or the compound represented by
Chemical Formula 19(5) (example 4-9) was used.
Comparative Examples 4-1, 4-2
[0213] Secondary batteries were formed by the same steps as those
in Comparative Examples 1-1 and 1-2, except that as in the case of
Examples 4-1 to 4-9, as the anode active material, silicon was used
to form the anode active material layer 34B.
[0214] When the cycle characteristics and the storage
characteristics of the secondary batteries of Examples 4-1 to 4-9
and Comparative Examples 4-1 to 4-2 were determined, results shown
in Table 4 were obtained.
TABLE-US-00004 TABLE 4 Anode active material: silicon
ROOM-TEMPERATURE HIGH-TEMPERATURE CYCLE DISCHARGE STORAGE DISCHARGE
SOLVENT CAPACITY RETENTION CAPACITY ELECTROLYTE SULFONE COMPOUND
RATIO RETENTION RATIO SALT KIND KIND WT % (%) (%) EXAMPLE 4-1
LiPF.sub.6 EC + DEC CHEMICAL 0.01 44 78 EXAMPLE 4-2 1 mol/kg
FORMULA 19(2) 1 50 84 EXAMPLE 4-3 2 55 85 EXAMPLE 4-4 5 58 85
EXAMPLE 4-5 10 58 84 EXAMPLE 4-6 CHEMICAL 2 60 83 FORMULA 19(1)
EXAMPLE 4-7 CHEMICAL 2 58 84 FORMULA 19(3) EXAMPLE 4-8 CHEMICAL 2
54 84 FORMULA 19(4) EXAMPLE 4-9 CHEMICAL 2 52 82 FORMULA 19(5)
COMPARATIVE LiPF.sub.6 EC + DEC -- -- 41 75 EXAMPLE 4-1 1 mol/kg
COMPARATIVE CHEMICAL 1 43 80 EXAMPLE 4-2 FORMULA 34
[0215] As shown in Table 4, in the case where silicon was used as
the anode active material, substantially the same results as those
shown in Table 1 were obtained. In other words, in Examples 4-1 to
4-5 in which the solvent included the compound represented by
Chemical Formula 19(2), a higher room-temperature cycle discharge
capacity retention ratio and a higher high-temperature storage
discharge capacity retention ratio than those in Comparative
Examples 4-1 and 4-2 in which the compound represented by Chemical
Formula 19(2) was not included were obtained, and in Examples 4-6
to 4-9 in which the solvent included the compound represented by
Chemical Formula 19(1) or the like, a room-temperature cycle
discharge capacity retention ratio and a high-temperature storage
discharge capacity retention ratio which were substantially equal
to those in Example 4-3 in which the compound represented by
Chemical Formula 19(2) was included were obtained. In this case,
when the content of the compound represented by Chemical Formula
19(2) in the solvent was within a range from 0.01 wt % to 10 wt %
both inclusive, a high room-temperature cycle discharge capacity
retention ratio and a high high-temperature storage discharge
capacity retention ratio were obtained.
[0216] Therefore, it was confirmed that in the secondary battery
according to the embodiment, in the case where the anode 34
included silicon as the anode active material, when the solvent of
the electrolytic solution included the sulfone compound represented
by Chemical Formula 11, the cycle characteristics and the storage
characteristics were improved. It was confirmed that in this case,
the content of the compound represented by Chemical Formula 11 in
the solvent was within a range from 0.01 wt % to 10 wt % both
inclusive, superior characteristics were obtained, and when the
content was within a range from 1 wt % to 10 wt % both inclusive,
the characteristics were further improved.
Example 5-1
[0217] A secondary battery was formed by the same steps as those in
Example 4-3, except that as the solvent, PC was added. At that
time, the mixture ratio of EC, DEC and PC was a weight ratio of
20:60:20.
Examples 5-2 and 5-3
[0218] Secondary batteries were formed by the same steps as those
in Example 4-3, except that as the solvent, instead of DEC, EMC
(Example 5-2) or DMC (Example 5-3) was used.
Example 5-4
[0219] A secondary battery was formed by the same steps as those in
Example 4-3, except that as the solvent, instead of EC, FEC was
used.
Examples 5-5 to 5-11
[0220] Secondary batteries were formed by the same steps as those
in Example 4-2, except that as the solvent, VC (Example 5-5), FEC
(Example 5-6), t-DFEC (Example 5-7), c-DFEC (Example 5-8), BFDMC
(Example 5-9), PRS (Example 5-10), or SBAH (Example 5-11) was
added. At that time, the content of VC or the like in the solvent
was 5 wt %.
Comparative Examples 5-1 to 5-4
[0221] Secondary batteries were formed by the same steps as those
in Examples 5-4 to 5-7, except that the compound represented by
Chemical Formula 19(2) was not added.
[0222] When the cycle characteristics and the storage
characteristics of the secondary batteries of Example 5-1 to 5-11
and Comparative Examples 5-1 to 5-4 were determined, results shown
in Table 5 were obtained.
TABLE-US-00005 TABLE 5 Anode active material: silicon HIGH-
TEMPERATURE ROOM-TEMPERATURE STORAGE SOLVENT CYCLE DISCHARGE
DISCHARGE SULFONE CAPACITY RETENTION CAPACITY ELECTROLYTE COMPOUND
RATIO RETENTION RATIO SALT KIND KIND WT % (%) (%) EXAMPLE 4-2
LiPF.sub.6 EC + DEC CHEMICAL 1 50 84 EXAMPLE 4-3 1 mol/kg FORMULA 2
55 85 EXAMPLE 5-1 EC + DEC + PC 19(2) 2 56 86 EXAMPLE 5-2 EC + EMC
53 84 EXAMPLE 5-3 EC + DMC 54 84 EXAMPLE 5-4 FEC + DEC 84 88
EXAMPLE 5-5 EC + VC 1 80 83 EXAMPLE 5-6 DEC FEC 64 86 EXAMPLE 5-7
t-DFEC 85 89 EXAMPLE 5-8 c-DFEC 85 89 EXAMPLE 5-9 BFDMC 67 85
EXAMPLE 5-10 PRS 52 88 EXAMPLE 5-11 SBAH 54 90 COMPARATIVE
LiPF.sub.6 EC + DEC -- -- 41 75 EXAMPLE 4-1 1 mol/kg COMPARATIVE
FEC + DEC 78 75 EXAMPLE 5-1 COMPARATIVE EC + VC 70 79 EXAMPLE 5-2
DEC COMPARATIVE FEC 58 76 EXAMPLE 5-3 COMPARATIVE t-DFEC 80 82
EXAMPLE 5-4
[0223] As shown in Table 5, in the case where silicon was used as
the anode active material, substantially the same results as those
shown in Table 2 were obtained. In other words, in Examples 5-1 to
5-4 in which the solvent included the compound represented by
Chemical Formula 19(2) and PC or the like, the room-temperature
cycle discharge capacity retention ratio and the high-temperature
storage discharge capacity retention ratio were higher than those
in Comparative Example 4-1 in which the compound represented by
Chemical Formula 19(2) was not included, and a room-temperature
cycle discharge capacity retention ratio and a high-temperature
discharge capacity retention ratio which were substantially equal
to or higher than those in Example 4-3 in which PC or the like was
not included were obtained. Moreover, in Examples 5-5 to 5-11 in
which the solvent included VC or the like, the room-temperature
cycle discharge capacity retention ratio was higher than that in
Example 4-2 in which VC or the like was not included, and the
high-temperature storage discharge capacity retention ratio was
substantially equal to or higher than that in Example 4-2. In
particular, there was a tendency that the room-temperature cycle
discharge capacity retention ratio and the high-temperature storage
discharge capacity retention ratio in the case where t-DFEC as the
dihalogenated carbonate was included were higher than those in the
case where FEC as the monohalogenated carbonate was included.
[0224] Therefore, it was confirmed that in the secondary battery
according to the embodiment, even if the composition of the solvent
was changed, the cycle characteristics and the storage
characteristics were improved. It was confirmed that in this case,
even in the case where the propylene carbonate or the like was
added to the solvent, high characteristics were obtained, and in
the case where the cyclic carbonate including an unsaturated bond,
at least one kind selected from the group consisting of the chain
carbonate represented by Chemical Formula 20 which included a
halogen and the cyclic carbonate represented by Chemical Formula 21
which included a halogen, the sultone, or the acid anhydride was
added to the solvent, the characteristics were further
improved.
Examples 6-1 to 6-3
[0225] Secondary batteries were formed by the same steps as those
in Example 4-3, except that as the electrolyte salt, LiBF.sub.4
(Example 6-1), the compound represented by Chemical Formula 27(6)
(Example 6-2), or the compound represented by Chemical Formula
28(6) (Example 6-3) was added. At that time, the concentration of
lithium hexafluorophosphate in the electrolytic solution was 0.9
mol/kg, and the concentration of lithium tetrafluoroborate or the
like was 0.1 mol/kg.
[0226] When the cycle characteristics and the storage
characteristics of the secondary batteries of Examples 6-1 to 6-3
were determined, results shown in Table 6 were obtained.
TABLE-US-00006 TABLE 6 Anode active material: silicon
ROOM-TEMPERATURE HIGH-TEMPERATURE SOLVENT CYCLE DISCHARGE STORAGE
DISCHARGE SULFONE CAPACITY RETENTION CAPACITY COMPOUND RATIO
RETENTION RATIO ELECTROLYTE SALT KIND KIND WT % (%) (%) EXAMPLE 4-3
LiPF.sub.6 EC + CHEMICAL 2 55 85 1 mol/kg DEC FORMULA EXAMPLE 6-1
LiPF.sub.6 LiBF.sub.4 19(2) 56 86 0.9 mol/kg 0.1 mol/kg EXAMPLE 6-2
LiPF.sub.6 CHEMICAL 58 88 0.9 mol/kg FORMULA 27(6) 0.1 mol/kg
EXAMPLE 6-3 LiPF.sub.6 CHEICAL 56 89 0.9 mol/kg FORMULA 28(6) 0.1
mol/kg
[0227] As shown in Table 6, in the case where silicon was used as
the anode active material, the same results as those shown in Table
3 were obtained. In other words, in Examples 6-1 to 6-3 in which
the electrolyte salt included lithium tetrafluoroborate or the
like, the room-temperature cycle discharge capacity retention ratio
and the high-temperature storage discharge capacity retention ratio
were higher than those in Example 4-3 in which lithium
tetrafluoroborate or the like was not included.
[0228] Therefore, it was confirmed that in the secondary battery
according to the embodiment, even if the kind of the electrolyte
salt was changed, the cycle characteristics and the storage
characteristics were improved. It was confirmed that in this case,
when the electrolyte salt included lithium tetrafluoroborate, the
compound represented by Chemical Formula 24 or the compound
represented by Chemical Formula 25, the characteristics were
further improved.
[0229] It was confirmed from the above-described results shown in
Tables 1 to 6 that in the secondary battery according to the
embodiment, when the solvent of the electrolytic solution included
the sulfone compound represented by Chemical Formula 11,
irrespective of the kind of the anode active material or the
composition of the solvent, the cycle characteristics and the
storage characteristics were improved. It was confirmed that in
this case, in the case where silicon (the material being capable of
inserting and extracting lithium and including at least one kind
selected from the group consisting of metal elements and metalloid
elements) was used as the anode active material, the rate of
increase of the discharge capacity retention ratio was larger than
that in the case where the carbon material was used as the anode
active material, so a higher effect was obtained in the case where
silicon was used. It was considered that the result was obtained,
because when silicon which was advantageous to increase the
capacity was used as the anode active material, compared to the
case where the carbon material was used, the electrolytic solution
was easily decomposed, so the decomposition inhibition effect of
the electrolytic solution was exerted pronouncedly.
[0230] Next, examples of the electrolytic solution and the
secondary battery according to the second embodiment will be
described below.
Example 7-1
[0231] A laminate film type secondary battery shown in FIGS. 3 and
4 was formed using artificial graphite as the anode active
material. At that time, the secondary battery was a lithium-ion
secondary battery in which the capacity of the anode 34 was
represented on the basis of insertion and extraction of
lithium.
[0232] At first, the cathode 33 and the anode 34 were formed by the
same steps as those in Example 1-1.
[0233] Next, the electrolytic solution was prepared. At first,
after EC and DEC were mixed at a weight ratio of EC:DEC=30:70 to
form a mixture, FEC as the halogenated carbonate (the cyclic
carbonate represented by Chemical Formula 37 which included a
halogen) and the compound represented by Chemical Formula 46(2) as
the sulfone compound (the compound represented by Chemical Formula
35) were added to and mixed with the mixture to form a solvent. At
that time, the content of FEC in the solvent was 1 wt %, and the
content of the compound represented by Chemical Formula 46(2) in
the solvent was 0.01 wt %. The "wt %" is a unit in the case where
the whole solvent was 100 wt %, and the same holds for the
following examples. Finally, as the electrolyte salt, lithium
hexafluorophosphate (LiPF.sub.6) was dissolved in the solvent. At
that time, the concentration of the electrolyte salt in the
electrolytic solution was 1 mol/kg.
[0234] Next, the laminate film type secondary battery was formed
using the cathode 33 and the anode 34 by the same steps as those in
Example 1-1.
Examples 7-2 to 7-5
[0235] Secondary batteries were formed by the same steps as those
in Examples 7-1, except that the content of the compound
represented by Chemical Formula 46(2) in the solvent was 1 wt %
(Example 7-2), 2 wt % (Example 7-3), 5 wt % (Example 7-4) or 10 wt
% (Example 7-5).
Examples 7-6 to 7-12
[0236] Secondary batteries were formed by the same steps as those
in Example 7-2, except that instead of the compound represented by
Chemical Formula 46(2), the compound represented by Chemical
Formula 46(1) (Example 7-6), the compound represented by Chemical
Formula 46(3) (Example 7-7), the compound represented by Chemical
Formula 46(4) (Example 7-8), the compound represented by Chemical
Formula 46(5) (Example 7-9), the compound represented by Chemical
Formula 46(6) (Example 7-10), the compound represented by Chemical
Formula 46(7) (Example 7-11), or the compound represented by
Chemical Formula 46(8) (Example 7-12) was used.
Comparative Example 7-1
[0237] A secondary battery was formed by the same steps as those in
Example 7-1, except that FEC and the compound represented by
Chemical Formula 46(2) were not included.
Comparative Example 7-2
[0238] A secondary battery was formed by the same steps as those in
Example 7-1, except that the compound represented by Chemical
Formula 46(2) was not included.
Comparative Example 7-3
[0239] A secondary battery was formed by the same steps as those in
Example 7-2, except that FEC was not included.
Comparative Examples 7-4 and 7-5
[0240] Secondary batteries were formed by the same steps as those
in Comparative Examples 7-1 and 7-3, except that as the solvent, VC
was added. At that time, the content of VC in the solvent was 1 wt
%.
[0241] When the cycle characteristics, the storage characteristics
and the swelling characteristics of the secondary batteries of
Examples 7-1 to 7-12 and Comparative Examples 7-1 to 7-5 were
determined, results shown in Table 7 were obtained.
[0242] To determine the swelling characteristics, after two cycles
of charge and discharge were performed on each of the secondary
batteries in an atmosphere at 23.degree. C., each of the secondary
batteries was charged again, and the thickness of each of the
secondary batteries was determined. Then, after each of the
secondary batteries which was still in a charged state was stored
for 4 hours in a constant temperature bath at 90.degree. C., the
thickness of each of the secondary batteries was determined. Then,
swelling (mm)=(thickness after storage-thickness before storage)
was determined by calculation.
[0243] In addition, in the following examples and the following
comparative examples, the steps and the conditions when determining
the cycle characteristics and the storage characteristics were the
same as those described above.
TABLE-US-00007 TABLE 7 Anode active material: artificial graphite
ROOM- HIGH- TEMPERATURE TEMPERATURE CYCLE STORAGE DISCHARGE
DISCHARGE CAPACITY CAPACITY SOLVENT RETENTION RETENTION ELECTROLYTE
HALOGENATED SULFONE COMPOUND RATIO RATIO SWELLING SALT KIND
CARBONATE KIND WT % (%) (%) (mm) EXAMPLE 7-1 LiPF.sub.6 EC + FEC
CHEMICAL 0.01 86 87 -- EXAMPLE 7-2 1 mol/kg DEC FORMULA 46(2) 1 90
90 0.321 EXAMPLE 7-3 2 86 90 -- EXAMPLE 7-4 5 84 88 -- EXAMPLE 7-5
10 82 86 -- EXAMPLE 7-6 CHEMICAL 1 89 90 -- FORMULA 46(1) EXAMPLE
7-7 CHEMICAL 1 86 87 -- FORMULA 46(3) EXAMPLE 7-8 CHEMICAL 1 91 90
-- FORMULA 46(4) EXAMPLE 7-9 CHEMICAL 1 91 90 -- FORMULA 46(5)
EXAMPLE 7-10 CHEMICAL 1 86 88 -- FORMULA 46(6) EXAMPLE 7-11
CHEMICAL 1 85 90 -- FORMULA 46(7) EXAMPLE 7-12 CHEMICAL 1 85 90 --
FORMULA 46(8) COMPARATIVE LiPF.sub.6 EC + -- -- -- 80 84 0.248
EXAMPLE 7-1 1 mol/kg DEC COMPARATIVE FEC -- -- 84 85 0.500 EXAMPLE
7-2 COMPARATIVE -- CHEMICAL 1 82 86 -- EXAMPLE 7-3 FORMULA 46(2)
COMPARATIVE EC + -- -- -- 84 85 -- EXAMPLE 7-4 DEC + COMPARATIVE VC
-- CHEMICAL 1 85 86 -- EXAMPLE 7-5 FORMULA 46(2)
[0244] As shown in Table 7, in Examples 7-1 to 7-12 in which the
solvent included FEC and the compounds represented by Chemical
Formulas 46(1) to 46(8), compared to Comparative Examples 7-1 to
7-5 in which neither of them was included, or only one of them was
included, a substantially equal or higher room-temperature cycle
discharge capacity retention ratio and a substantially equal or
higher high-temperature storage discharge capacity retention ratio
were obtained.
[0245] More specifically, in Examples 7-1 to 7-5 in which the
solvent included FEC and the compound represented by Chemical
Formula 46(2), the room-temperature cycle discharge capacity
retention ratio and the high-temperature storage discharge capacity
retention ratio were higher than those in Comparative Example 7-1
in which neither of them was included. In this case, when the
content of the compound represented by Chemical Formula 46(2) in
the solvent was within a range from 0.01 wt % to 10 wt % both
inclusive, a high room-temperature cycle discharge capacity
retention ratio and a high high-temperature storage discharge
capacity retention ratio were obtained. When the content of the
compound represented by Chemical Formula 46(2) was smaller than
0.01 wt % or larger than 10 wt %, the room-temperature cycle
discharge capacity retention ratio and the high-temperature storage
discharge capacity retention ratio were greatly reduced, and when
the content was larger than 10 wt %, the capacity showed a tendency
to be greatly reduced. In Examples 7-6 to 7-12 in which the solvent
included the compound represented by Chemical Formula 46(1) or the
like, the results were the same as those described in Examples 7-1
to 7-5.
[0246] Moreover, in Examples 7-1 to 7-5, the room-temperature cycle
discharge capacity retention ratio was substantially equal to or
higher than that in Comparative Example 7-2 in which the solvent
included only FEC. However, the high-temperature storage discharge
capacity retention ratio was higher than that in Comparative
Example 7-2. In this case, when the content of the compound
represented by Chemical Formula 46(2) was within a range from 0.01
wt % to 2 wt % both inclusive, the room-temperature cycle discharge
capacity retention ratio was also higher.
[0247] Further, in Examples 7-2, and 7-6 to 7-12, compared to
Comparative Example 7-3 in which the solvent included only the
compound represented by Chemical Formula 46(2), the
room-temperature cycle discharge capacity retention ratio and the
high-temperature storage discharge capacity retention ratio were
higher, and both values were a high 80's percent.
[0248] Therefore, it was confirmed that in the secondary battery
according to the embodiment, in the case where the anode 34
included artificial graphite as the anode active material, when the
solvent of the electrolytic solution included both of the sulfone
compound and the halogenated carbonate, the cycle characteristics
and the storage characteristics were improved. It was confirmed
that in this case, when the content of the compound represented by
Chemical Formula 35 in the solvent was within a range from 0.01 wt
% to 10 wt % both inclusive, superior characteristics were
obtained.
[0249] Moreover, when Examples 7-2, 7-6 and 7-7 which had a
commonality in that R1 in Chemical Formula 35 was a straight-chain
alkylene group were compared, there was a tendency that in Examples
7-2 and 7-6 in which the number of carbon atoms in R1 was 2 or
less, the room-temperature cycle discharge capacity retention ratio
and the high-temperature storage discharge capacity retention ratio
were higher than those in Example 7-7 in which the number of carbon
atoms in R1 was 3 or more. This tendency was the same in Examples
7-8 to 7-10 which had a commonality in that R1 was a halogenated
alkylene group.
[0250] Therefore, it was confirmed that in the secondary battery
according to the embodiment, in the case where R1 in Chemical
Formula 35 was a straight-chain alkylene group or a halogenated
alkylene group, when the number of carbon atoms was 2 or less, the
cycle characteristics and the storage characteristics were further
improved.
[0251] Further, with reference to swelling in Comparative Example
7-1 in which the solvent did not include FEC and the compound
represented by Chemical Formula 46(2), in Comparative Example 7-2
in which only FEC was included, swelling was greatly increased, and
in Example 7-2 in which FEC and the compound represented by
Chemical Formula 46(2) were included, an increase in swelling was
reduced.
[0252] This result showed the following. FEC had an advantage of
greatly increasing the room-temperature cycle discharge capacity
retention ratio. However, it was difficult for FEC to greatly
increase the high-temperature storage discharge capacity retention
ratio, and FEC had a disadvantage of greatly increasing swelling.
Moreover, the compound represented by Chemical Formula 46(2) had an
advantage of preventing swelling. However, the compound had a
disadvantage of being unable to greatly increase the
room-temperature cycle discharge capacity retention ratio and the
high-temperature storage discharge capacity retention ratio. On the
other hand, when FEC and the compound represented by Chemical
Formula 46(2) were used together, while swelling was prevented, the
room-temperature cycle discharge capacity retention ratio and the
high-temperature storage discharge capacity retention ratio were
greatly increased.
[0253] In Comparative Examples 7-4 and 7-5 in which the solvent
included VC, the room-temperature cycle discharge capacity
retention ratio and the high-temperature storage discharge capacity
retention ratio were higher than those in Comparative Example 7-1,
but the room-temperature cycle discharge capacity retention ratio
and the high-temperature storage discharge capacity retention ratio
in Comparative Examples 7-4 and 7-5 did not exceed those in Example
7-2 in which FEC was included. This result showed that to increase
the room-temperature cycle discharge capacity retention ratio and
the high-temperature storage discharge capacity retention ratio,
FEC had an advantage over VC.
[0254] Therefore, it was confirmed that in the secondary battery
according to the embodiment, when the sulfone compound was used
with the halogenated carbonate, not only the cycle characteristics
and the storage characteristics but also the swelling
characteristics were improved. It was confirmed that in this case,
a higher effect than that in the case where the sulfone compound
was used with the cyclic carbonate including an unsaturated bond
was obtained.
[0255] The result in the case where the solvent includes
fluoromethyl methyl carbonate is not shown here. However,
fluoromethyl methyl carbonate has the same functions as FEC, so it
is obvious that even in the case where fluoromethyl methyl
carbonate is included, the same effects are obtained. The same
holds for the case where two or more above-described halogenated
carbonates of the same kind or different kinds are mixed.
Examples 8-1 and 8-2
[0256] Secondary batteries were formed by the same steps as those
in Example 7-2, except that as the halogenated carbonate (the
cyclic carbonate represented by Chemical Formula 37 which included
a halogen), instead of FEC, t-DFEC (Example 8-1) or c-DFEC (Example
8-2) was used.
Example 8-3
[0257] A secondary battery was formed by the same steps as those in
Example 8-2, except that as the halogenated carbonate (the chain
carbonate represented by Chemical Formula 36 which included a
halogen), BFDMC was added. At that time, the content of BFDMC in
the solvent was 1 wt %.
Comparative Example 8
[0258] A secondary battery was formed by the same steps as those in
Example 8-1, except that the compound represented by Chemical
Formula 46(2) was not included.
[0259] When the cycle characteristics, the storage characteristics
and the swelling characteristics of the secondary batteries of
Examples 8-1 to 8-3 and Comparative Example 8 were determined,
results shown in Table 8 were obtained.
TABLE-US-00008 TABLE 8 Anode active material: artificial graphite
ROOM- HIGH- TEMPERATURE TEMPERATURE CYCLE STORAGE DISCHARGE
DISCHARGE SOLVENT CAPACITY CAPACITY ELECTRO- HALO- SULFONE
RETENTION RETENTION LYTE GENATED COMPOUND RATIO RATIO SWELLING SALT
KIND CARBONATE KIND WT % (%) (%) (mm) EXAMPLE 7-2 LiPF.sub.6 EC +
FEC CHEMICAL 1 90 90 0.321 EXAMPLE 8-1 1 mol/kg DEC t-DFEC FORMULA
92 91 0.401 EXAMPLE 8-2 c-DFEC 46(2) 92 90 -- EXAMPLE 8-3 FEC +
BFDMC 92 91 -- COMPARATIVE LiPF.sub.6 EC + -- -- -- 80 84 0.248
EXAMPLE 7-1 1 mol/kg DEC COMPARATIVE t-DFEC -- -- 85 85 0.851
EXAMPLE 8
[0260] As shown in Table 8, in Examples 8-1 and 8-2 in which the
solvent included t-DFEC or the like, compared to Example 7-2 in
which FEC was included, the room-temperature cycle discharge
capacity retention ratio was higher, and the high-temperature
storage discharge capacity retention ratio was equal or higher. In
Example 8-1 in which the solvent included the compound represented
by Chemical Formula 46(2), the room-temperature cycle discharge
capacity retention ratio and high-temperature storage discharge
capacity retention ratio were higher than those in Comparative
Example 8 in which the compound represented by Chemical Formula
46(2) was not included. In Example 8-3 in which the solvent
included FEC and BFDMC, a room-temperature cycle discharge capacity
retention ratio and a high-temperature storage discharge capacity
retention ratio which were substantially equal to those in Examples
8-1 and 8-2 in which t-DFEC or the like was included were
obtained.
[0261] With reference to swelling in Comparative Example 8 in which
the solvent did not include FEC and the compound represented by
Chemical Formula 46(2), in Comparative Example 8 in which only
t-DFEC was included, swelling was greatly increased, but in Example
8-1 in which t-DFEC and the compound represented by Chemical
Formula 46(2) were included, an increase in swelling was
reduced.
[0262] These result showed the following. Although t-DFEC or the
like had an advantage of increasing the room-temperature cycle
discharge capacity retention ratio and the high-temperature storage
discharge capacity retention ratio over FEC, t-DFEC or the like had
a disadvantage of greatly increasing swelling. However, when t-DFEC
or the like was used with the compound represented by Chemical
Formula 46(2), while swelling was prevented, the room-temperature
cycle discharge capacity retention ratio and the high-temperature
storage discharge capacity retention ratio were greatly
increased.
[0263] Therefore, it was confirmed that in the secondary battery
according to the embodiment, even if the kind of the halogenated
carbonate was changed, the cycle characteristics, the storage
characteristics and the swelling characteristics were improved. It
was confirmed that in this case, when the dihalogenated carbonate
rather than the monohalogenated carbonate was used as the
halogenated carbonate, the characteristics were further
improved.
Example 9-1
[0264] A secondary battery was formed by the same steps as those in
Example 7-2, except that as the solvent, propylene carbonate (PC)
was added. At that time, the mixture ratio of EC, DEC and PC was a
weight ratio of 20:60:20.
Examples 9-2 and 9-3
[0265] Secondary batteries were formed by the same steps as those
in Example 7-2, except that as the solvent, instead of DEC, EMC
(Example 9-2) or DMC (Example 9-3) was used.
Examples 9-4 and 9-5
[0266] Secondary batteries were formed by the same steps as those
in Example 7-2, except that as the solvent, PRS (Example 9-4) as
the sultone or SBAH (Example 9-5) as the acid anhydride was added.
At that time, the content of PRS or the like in the solvent was 1
wt %.
[0267] When the cycle characteristics and the storage
characteristics of the secondary batteries of Examples 9-1 to 9-5
were determined, results shown in Table 9 were obtained.
TABLE-US-00009 TABLE 9 Anode active material: artificial graphite
ROOM- HIGH- TEMPERATURE TEMPERATURE CYCLE STORAGE DISCHARGE
DISCHARGE SOLVENT CAPACITY CAPACITY SULFONE RETENTION RETENTION
ELECTROLYTE HALOGENATED COMPOUND RATIO RATIO SALT KIND CARBONATE
KIND WT % (%) (%) EXAMPLE 7-2 LiPF.sub.6 -- FEC CHEMICAL 1 90 90
EXAMPLE 9-1 1 mol/kg EC + DEC + FORMULA 89 92 PC 46(2) EXAMPLE 9-2
EC + 89 88 EMC EXAMPLE 9-3 EC + 89 86 DMC EXAMPLE 9-4 EC + DEC + 90
92 PRS EXAMPLE 9-5 EC + DEC + 92 94 SBAH
[0268] As shown in Table 9, in Examples 9-1 to 9-5 in which the
solvent included PC or the like, compared to Example 7-2 in which
PC or the like was not included, the room-temperature cycle
discharge capacity retention ratio and the high-temperature storage
discharge capacity retention ratio were substantially equal or
higher, and were a high 80's percent or higher. In this case, in
Examples 9-1, 9-4 and 9-5 in which PC or the like was added in the
solvent, compared to Examples 9-2 and 9-3 in which EMC or the like
was substituted for a part of the solvent, the room-temperature
cycle discharge capacity retention ratio was equal or higher, and
the high-temperature storage discharge capacity retention ratio was
higher.
[0269] Therefore, it was confirmed that in the secondary battery
according to the embodiment, even if the composition of the solvent
was changed, the cycle characteristics and the storage
characteristics were improved. It was confirmed that in this case,
when PC or the like was added to the solvent, the characteristics
were further improved.
Examples 10-1 to 10-3
[0270] Secondary batteries were formed by the same steps as those
in Example 7-2, except that as the electrolyte salt, lithium
tetrafluoroborate (Example 10-1), the compound represented by
Chemical Formula 27(6) as the compound represented by Chemical
Formula 24 (Example 10-2) or the compound represented by Chemical
Formula 33(1) as the compound represented by Chemical Formula 31
(Example 10-3) was added. At that time, the concentration of
lithium hexafluorophosphate in the electrolytic solution was 0.9
mol/kg, and the concentration of lithium tetrafluoroborate or the
like was 0.1 mol/kg.
[0271] When the cycle characteristics and the storage
characteristics of the secondary batteries of Examples 10-1 to 10-3
were determined, results shown in Table 10 were obtained.
TABLE-US-00010 TABLE 10 Anode active material: artificial graphite
ROOM- HIGH- TEMPERATURE TEMPERATURE CYCLE STORAGE DISCHARGE
DISCHARGE SOLVENT CAPACITY CAPACITY SULFONE RETENTION RETENTION
HALOGENATED COMPOUND RATIO RATIO ELECTROLYTE SALT KIND CARBONATE
KIND WT % (%) (%) EXAMPLE 7-2 LiPF.sub.6 EC + FEC CHEMICAL 1 90 90
1 mol/kg DEC FORMULA EXAMPLE 10-1 LiPF.sub.6 LIBF.sub.4 46(2) 90 92
0.9 mol/kg 0.1 mol/kg EXAMPLE 10-2 LiPF.sub.6 CHEMICAL 91 92 0.9
mol/kg FORMULA 27(6) 0.1 mol/kg EXAMPLE 10-3 LiPF.sub.6 CHEMICAL 90
91 0.9 mol/kg FORMULA 33(1) 0.1 mol/kg
[0272] As shown in Table 10, in Examples 10-1 to 10-3 in which the
electrolyte salt included lithium tetrafluoroborate or the like,
compared to Example 7-2 in which lithium tetrafluoroborate or the
like was not included, the room-temperature cycle discharge
capacity retention ratio was equal or higher, and the
high-temperature storage discharge capacity retention ratio was
higher.
[0273] Therefore, it was confirmed in the secondary battery
according to the embodiment, even if the kind of the electrolyte
salt was changed, the cycle characteristics and the storage
characteristics were improved. It was confirmed that in this case,
when the electrolyte salt included lithium tetrafluoroborate, the
compound represented by Chemical Formula 24 or the compound
represented by Chemical Formula 31, the characteristics were
further improved.
[0274] The result in the case where the electrolyte salt includes
at least one kind selected from the group consisting of lithium
perchlorate and lithium hexafluoroarsenate, at least one kind
selected from the group consisting of the compounds represented by
Chemical Formulas 25 and 26, or at least one kind selected from the
group consisting of the compounds represented by Chemical Formulas
30 and 31 is not shown here. However, lithium perchlorate or the
like has the same functions as lithium tetrafluoroborate or the
like, so it is obvious that even in the case where lithium
perchlorate or the like is included, the same effects are obtained.
The same holds for the case where two or more above-described
electrolyte salts of the same kind or different kinds are
mixed.
Examples 11-1 to 11-12
[0275] Secondary batteries were formed by the same steps as those
in Examples 7-1 to 7-12, except that as the anode active material,
instead of artificial graphite, silicon was used to form the anode
active material layer 34B, and the content of FEC was changed to 5
wt %. In the case where the anode active material layer 34B was
formed, silicon was deposited on the anode current collector 34A by
an electron beam evaporation method.
Comparative Examples 11-1 to 11-5
[0276] Secondary batteries were formed by the same steps as those
in Comparative Examples 7-1 to 7-5, except that as in the case of
Examples 11-1 to 11-12, as the anode active material, silicon was
used to form the anode active material layer 34B.
[0277] When the cycle characteristics, the storage characteristics
and the swelling characteristics of the secondary batteries of
Examples 11-1 to 11-12 and Comparative Examples 11-1 to 11-5 were
determined, results shown in Table 11 were obtained.
TABLE-US-00011 TABLE 11 Anode active material: silicon ROOM- HIGH-
TEMPERATURE TEMPERATURE CYCLE STORAGE DISCHARGE DISCHARGE SOLVENT
CAPACITY CAPACITY ELECTRO- HALO- SULFONE RETENTION RETENTION LYTE
GENATED COMPOUND RATIO RATIO SWELLING SALT KIND CARBONATE KIND WT %
(%) (%) (mm) EXAMPLE 11-1 LiPF.sub.6 EC + FEC CHEMICAL 0.01 60 87
-- EXAMPLE 11-2 1 mol/kg DEC FORMULA 1 64 90 0.425 EXAMPLE 11-3
46(2) 2 69 90 -- EXAMPLE 11-4 5 73 88 -- EXAMPLE 11-5 10 76 88 --
EXAMPLE 11-6 CHEMICAL 1 69 90 -- FORMULA 46(1) EXAMPLE 11-7
CHEMICAL 1 60 87 -- FORMULA 46(3) EXAMPLE 11-8 CHEMICAL 1 67 88 --
FORMULA 46(4) EXAMPLE 11-9 CHEMICAL 1 65 88 -- FORMULA 46(5)
EXAMPLE 11- CHEMICAL 1 62 88 -- 10 FORMULA 46(6) EXAMPLE 11-
CHEMICAL 1 60 87 -- 11 FORMULA 46(7) EXAMPLE 11- CHEMICAL 1 61 87
-- 12 FORMULA 46(8) COMPARATIVE LiPF.sub.6 EC + -- -- -- 41 82
0.267 EXAMPLE 11-1 1 mol/kg DEC COMPARATIVE FEC -- -- 58 86 0.601
EXAMPLE 11-2 COMPARATIVE -- CHEMICAL 1 50 86 -- EXAMPLE 11-3
FORMULA 46(2) COMPARATIVE EC + -- -- -- 70 85 -- EXAMPLE 11-4 DEC +
COMPARATIVE VC -- CHEMICAL 1 68 85 -- EXAMPLE 11-5 FORMULA
46(2)
[0278] As shown in Table 11, in the case where silicon was used as
the anode active material, substantially the same results as those
shown in Table 7 were obtained. In other words, in the case where
the solvent included FEC and the compounds represented by Chemical
Formulas 46(1) to 46(8), when the content of the compound
represented by Chemical Formula 46(2) in the solvent was 0.01 wt %
to 10 wt % both inclusive, a room-temperature cycle discharge
capacity retention ratio and a high-temperature storage discharge
capacity retention ratio which were substantially equal to or
higher than those in the case where neither of them was included,
or the case where only one of them was included were obtained.
Moreover, when the cases where there was a commonality in that R1
in Chemical Formula 35 was a straight-chain alkylene group or a
halogenated alkylene group were compared, there was a tendency that
in the case where the number of carbon atoms in R1 was 2 or less,
the room-temperature cycle discharge capacity retention ratio and
the high-temperature storage discharge capacity retention ratio
were equal to or higher than those in the case where the number of
carbon atoms in R1 is 3 or more. Further, with reference to
swelling in the case where the solvent did not include FEC and the
compound represented by Chemical Formula 46(2), in the case where
only FEC was included, swelling was greatly increased. However, in
the case where FEC and the compound represented by Chemical Formula
46(2) were included, an increase in swelling was reduced. In
particular, in the case where the solvent included VC, the
room-temperature cycle discharge capacity retention ratio and the
high-temperature storage discharge capacity retention ratio did not
exceed those in the case where FEC was included.
[0279] Therefore, it was confirmed in the secondary battery
according to the embodiment, in the case where the anode 34
included silicon as the anode active material, when the solvent of
the electrolytic solution included both of the sulfone compound and
the halogenated carbonate, the cycle characteristics and the
storage characteristics were improved. It was confirmed that in
this case, when the content of the compound represented by Chemical
Formula 35 in the solvent was within a range from 0.01 wt % to 10
wt % both inclusive, superior characteristics were obtained, and in
the case where R1 in Chemical Formula 35 was a straight-chain
alkylene group or a halogenated alkylene group, when the number of
carbon atoms was 2 or less, the characteristics were further
improved. Moreover, it was confirmed that when the sulfone compound
was used with the halogenated carbonate, not only the cycle
characteristics and the storage characteristics but also the
swelling characteristics were improved.
Examples 12-1 to 12-3
[0280] Secondary batteries were formed by the same steps as those
in Examples 8-1 to 8-3, except that as in the case of Examples 11-1
to 11-12, silicon was used as the anode active material to form the
anode active material layer 34B, and the content of t-DFEC or the
like was changed to 5 wt %.
Comparative Example 12
[0281] A secondary battery was formed by the same steps as those in
Comparative Example 8, except that as in the case of Examples 11-1
to 11-12, silicon was used as the anode active material to form the
anode active material layer 34B, and the content of t-DFEC was
changed to 5 wt %.
[0282] When the cycle characteristics, the storage characteristics
and the swelling characteristics of the secondary batteries of
Examples 12-1 to 12-3 and Comparative Example 12 were determined,
results shown in Table 12 were obtained.
TABLE-US-00012 TABLE 12 Anode active material: silicon ROOM- HIGH-
TEMPERATURE TEMPERATURE CYCLE STORAGE DISCHARGE DISCHARGE SOLVENT
CAPACITY CAPACITY ELECTRO- HALO- SULFONE RETENTION RETENTION LYTE
GENATED COMPOUND RATIO RATIO SWELLING SALT KIND CARBONATE KIND WT %
(%) (%) (mm) EXAMPLE 11-2 LiPF.sub.6 -- FEC CHEMICAL 1 64 90 0.425
EXAMPLE 12-1 1 mol/kg EC + t-DFEC FORMULA 84 91 0.531 EXAMPLE 12-2
DEC c-DFEC 46(2) 83 90 -- EXAMPLE 12-3 FEC + BFDMC 64 88 --
COMPARATIVE LiPF.sub.6 EC + -- -- -- 41 82 0.267 EXAMPLE 11-1 1
mol/kg DEC COMPARATIVE t-DFEC -- -- 80 85 0.866 EXAMPLE 12
[0283] As shown in Table 12, in the case where silicon was used as
the anode active material, substantially the same results as those
in Table 8 were obtained. In other words, in the case where the
solvent included t-DFEC or the like, compared to the case where FEC
was included, the room-temperature cycle discharge capacity
retention ratio was higher, and the high-temperature storage
discharge capacity retention ratio was equal or higher. In the case
where the solvent included the compound represented by Chemical
Formula 46(2), the room-temperature cycle discharge capacity
retention ratio and the high-temperature storage discharge capacity
retention ratio were higher than those in the case where the
compound represented by Chemical Formula 46(2) was not included. In
the case where the solvent included FEC and BFDMC, a
room-temperature cycle discharge capacity retention ratio and a
high-temperature storage discharge capacity retention ratio which
were substantially equal to those in the case where t-DFEC or the
like was included were obtained. In the case where the solvent
included only t-DFEC, swelling was greatly increased. However, in
the case where t-DFEC and the compound represented by Chemical
Formula 46(2) were included, an increase in swelling was
reduced.
[0284] Therefore, it was confirmed that in the secondary battery
according to the embodiment, in the case where the kind of the
halogenated carbonate was changed, the cycle characteristics, the
storage characteristics and the swelling characteristic were
improved. It was confirmed that in this case, when the
dihalogenated carbonate rather than the monohalogenated carbonate
was used as the halogenated carbonate, the characteristics were
further improved.
Examples 13-1 to 13-5
[0285] Secondary batteries were formed by the same steps as those
in Examples 9-1 to 9-5, except that as in the case where Examples
11-1 to 11-12, silicon was used as the anode active material to
form the anode active material layer 34B, and the content of FEC
was changed to 5 wt %.
[0286] When the cycle characteristics and the storage
characteristics of the secondary batteries of Examples 13-1 to 13-5
were determined, results shown in Table 13 were obtained.
TABLE-US-00013 TABLE 13 Anode active material: silicon ROOM- HIGH-
TEMPERATURE TEMPERATURE CYCLE STORAGE DISCHARGE DISCHARGE SOLVENT
CAPACITY CAPACITY SULFONE RETENTION RETENTION ELECTROLYTE
HALOGENATED COMPOUND RATIO RATIO SALT KIND CARBONATE KIND WT % (%)
(%) EXAMPLE 11-2 LiPF.sub.6 -- FEC CHEMICAL 1 64 90 EXAMPLE 13-1 1
mol/kg EC + DEC + FORMULA 64 92 PC 46(2) EXAMPLE 13-2 EC + 63 88
EMC EXAMPLE 13-3 EC + 63 86 DMC EXAMPLE 13-4 EC + DEC + 64 92 PRS
EXAMPLE 13-5 EC + DEC + 66 94 SBAH
[0287] As shown in Table 13, in the case where silicon was used as
the anode active material, substantially the same results as those
in Table 9 were obtained. In other words, in the case where the
solvent included PC or the like, compared to the case where PC or
the like was not included, the room-temperature cycle discharge
capacity retention ratio and the high-temperature storage discharge
capacity retention ratio were substantially equal or higher. In
this case, in the case where PC or the like was added to the
solvent, compared to the case where EMC or the like was substituted
for a part of the solvent, the room-temperature cycle discharge
capacity retention ratio was equal or higher, and the
high-temperature storage discharge capacity retention ratio was
higher.
[0288] Therefore, it was confirmed that in the secondary battery
according to the embodiment, even if the composition of the solvent
was changed, the cycle characteristics and the storage
characteristics were improved. It was confirmed that in this case,
when the PC or the like was added to the solvent, the
characteristics were further improved.
Examples 14-1 to 14-3
[0289] Secondary batteries were formed by the same steps as those
in Examples 10-1 to 10-3, except that as in the case of Examples
11-1 to 11-12, silicon was used as the anode active material to
form the anode active material layer 34B, and the content of the
FEC was changed to 5 wt %.
[0290] When the cycle characteristics and the storage
characteristics of the secondary batteries of Examples 14-1 to 14-3
were determined, results shown in Table 14 were obtained.
TABLE-US-00014 TABLE 14 Anode active material: silicon ROOM- HIGH-
TEMPERATURE TEMPERATURE CYCLE STORAGE DISCHARGE DISCHARGE SOLVENT
CAPACITY CAPACITY HALO- SULFONE RETENTION RETENTION GENATED
COMPOUND RATIO RATIO ELECTROLYTE SALT KIND CARBONATE KIND WT % (%)
(%) EXAMPLE 11-2 LiPF.sub.6 EC + FEC CHEMICAL 1 64 90 1 mol/kg DEC
FORMULA EXAMPLE 14-1 LiPF.sub.6 LIBF.sub.4 46(2) 64 92 0.9 mol/kg
0.1 mol/kg EXAMPLE 14-2 LiPF.sub.6 CHEMICAL 68 92 0.9 mol/kg
FORMULA 27(6) 0.1 mol/kg EXAMPLE 14-3 LiPF.sub.6 CHEMICAL 64 91 0.9
mol/kg FORMULA 33(1) 0.1 mol/kg
[0291] As shown in Table 14, in the case where silicon was used as
the anode active material, the same results as those in Table 10
were obtained. In other words, in the case where the electrolyte
salt included lithium tetrafluoroborate or the like, compared to
the case where lithium tetrafluoroborate or the like was not
included, the room-temperature cycle discharge capacity retention
ratio was equal or higher, and the high-temperature storage
discharge capacity retention ratio was higher.
[0292] Therefore, it was confirmed that in the secondary battery
according to the embodiment, even if the kind of the electrolyte
salt was changed, the cycle characteristics and the storage
characteristics were improved. It was confirmed that in this case,
when the electrolyte salt included lithium tetrafluoroborate, the
compound represented by Chemical Formula 24 or the compound
represented by Chemical Formula 31, the cycle characteristics and
the storage characteristics were further improved.
[0293] It was confirmed from the above-described results shown in
Tables 7 to 14 that in the secondary battery according to the
embodiment, the solvent of the electrolytic solution included the
sulfone compound represented by Chemical Formula 35 and at least
one kind selected from the group consisting of the chain carbonate
represented by Chemical Formula 36 which included a halogen and the
cycle carbonate represented by Chemical Formula 37 which included a
halogen, irrespective of the kind of the anode active material or
the composition of the solvent, the battery characteristics such as
the cycle characteristics, the storage characteristics and the
swelling characteristics were improved. It was confirmed that in
this case, in the case where silicon (the material being capable of
inserting and extracting lithium and including at least one kind
selected from metal elements and metalloid elements) was used as
the anode active material, the rate of increase of the discharge
capacity retention ratio was larger than that in the case where the
carbon material was used as the anode active material, so a higher
effect was obtained in the case where silicon was used. It was
considered that the result was obtained, because when silicon which
was advantageous to increase the capacity was used as the anode
active material, compared to the case where the carbon material was
used, the electrolytic solution was easily decomposed, so the
decomposition inhibition effect of the electrolytic solution was
exerted pronouncedly.
[0294] Finally, examples of the electrolytic solution and the
secondary battery according to the third embodiment will be
described below.
Example 15-1
[0295] A laminate film type secondary battery shown in FIGS. 3 and
4 was formed using artificial graphite as the anode active
material. At that time, the secondary battery was a lithium-ion
secondary battery in which the capacity of the anode 34 was
represented on the basis of insertion and extraction of
lithium.
[0296] At first, the cathode 33 and the anode 34 were formed by the
same steps as those in Example 1-1.
[0297] Next, after EC, DEC and the compound represented by Chemical
Formula 50(7) as the sulfone compound represented by Chemical
Formula 49 were mixed to form a solvent, lithium
hexafluorophosphate as the electrolyte salt was dissolved in the
solvent to form the electrolytic solution. At that time, the
mixture ratio of EC and DEC was a weight ratio of 30:70, and the
content of the compound represented by Chemical Formula 50(7) in
the solvent was 0.01 wt %, and the concentration of the electrolyte
salt in the electrolytic solution was 1 mol/kg. The "wt %" is a
unit in the case where the whole solvent was 100 wt %, and the same
holds for the following examples.
[0298] Next, the laminate film type secondary battery was formed
using the cathode 33 and the anode 34 by the same steps as those in
Example 1-1.
Examples 15-2 to 15-4
[0299] Secondary batteries were formed by the same steps as those
in Example 15-1, except that the content of the compound
represented by Chemical Formula 50(7) in the solvent was 1 wt %
(Example 15-2), 2 wt % (Example 15-3) or 5 wt % (Example 15-4).
Examples 15-5 to 15-7
[0300] Secondary batteries were formed by the same steps as those
in Example 15-2, except that instead of the compound represented by
Chemical Formula 50(7), the compound represented by Chemical
Formula 50(1) (Example 15-5), the compound represented by Chemical
Formula 51(6) (Example 15-6), or the compound represented by
Chemical Formula 52(1) (Example 15-7) was used.
Comparative Example 15-1
[0301] A secondary battery was formed by the same steps as those in
Example 15-1, except that the compound represented by Chemical
Formula 50(7) was not added.
Comparative Examples 15-2 to 15-4
[0302] Secondary batteries were formed by the same steps as those
in Example 15-2, except that instead of the sulfone compound
represented by Chemical Formula 49 (the compound represented by
Chemical Formula 50(7)), the sulfone compound represented by
Chemical Formula 53 (Comparative Example 15-2), the sulfone
compound represented by Chemical Formula 54 (Comparative Example
15-3) or the sulfone compound represented by Chemical Formula 55
(Comparative Example 15-4) was used.
[0303] When the cycle characteristics of the secondary batteries of
Examples 15-1 to 15-7 and Comparative Examples 15-1 to 15-4 were
determined, results shown in Table 15 were obtained.
TABLE-US-00015 TABLE 15 Anode active material: artificial graphite
DIS- CHARGE CAPAC- ITY SOLVENT RETEN- ELECTRO- SULFONE TION LYTE
COMPOUND RATIO SALT KIND KIND WT % (%) EXAMPLE LiPF.sub.6 EC + D
CHEMICAL 0.01 83 15-1 1 mol/kg EC FORMULA EXAMPLE 50(7) 1 87 15-2
EXAMPLE 2 87 15-3 EXAMPLE 5 85 15-4 EXAMPLE CHEMICAL 85 15-5
FORMULA 50(1)1 EXAMPLE CHEMICAL 1 89 15-6 FORMULA 51(6) EXAMPLE
CHEMICAL 1 85 15-7 FORMULA 52(1) COM- LiPF.sub.6 EC + D -- -- 80
PARATIVE 1 mol/kg EC EXAMPLE 15-1 COM- CHEMICAL 1 78 PARATIVE
FORMULA EXAMPLE 53 15-2 COM- CHEMICAL 1 76 PARATIVE FORMULA EXAMPLE
54 15-3 COM- CHEMICAL 1 78 PARATIVE FORMULA EXAMPLE 55 15-4
[0304] As shown in Table 15, in Examples 15-1 to 15-7 in which the
solvent included the sulfone compound represented by Chemical
Formula 49 (the compound represented by Chemical Formula 50(7) or
the like), compared to Comparative Example 15-1 in which the
sulfone compound represented by Chemical Formula 49 was not
included or Comparative Examples 15-2 to 15-4 in which other
sulfone compounds represented by Chemical Formulas 53 to 55 were
included, the discharge capacity retention ratio was higher. This
result showed that to improve the discharge capacity retention
ratio, the sulfone compound represented by Chemical Formula 49 was
more advantageous than other sulfone compounds represented by
Chemical Formulas 53 to 55. More specifically, with reference to
the discharge capacity retention ratio in Comparative Example 15-1
in which the solvent did not include any of the sulfone compounds,
in Comparative Examples 15-2 to 15-4 in which other sulfone
compounds represented by Chemical Formulas 53 to 55 were included,
the discharge capacity retention ratio was reduced. However, in
Examples 15-1 to 15-7 in which the sulfone compound represented by
Chemical Formula 49 was included, the discharge capacity retention
ratio was higher. In other words, in spite of a commonality in that
the sulfone compounds represented by Chemical Formulas 49 and 53 to
55 had a sulfonyl fluoride type structure, the other sulfone
compounds represented by Chemical Formulas 53 to 55 caused a
decline in the discharge capacity retention ratio. However, the
sulfone compound represented by Chemical Formula 49 caused an
increase in the discharge capacity retention ratio. The result
showed that to increase the discharge capacity retention ratio, the
sulfone compound having a sulfonyl fluoride type structure
preferably had a chain group including an unsaturated carbon
bond.
[0305] In particular, when attention was focused on the content of
the compound represented by Chemical Formula 50(7) in the solvent,
in the case where the content was within a range from 0.01 wt % to
5 wt % both inclusive, a high discharge capacity retention ratio
was obtained. In this case, there was a tendency that when the
content was smaller than 0.01 wt % or larger than 5 wt %, the
discharge capacity retention ratio was greatly reduced, and in the
case where the content was larger than 5 wt %, the capacity was
also greatly reduced.
[0306] Therefore, it was confirmed that in the secondary battery
according to the embodiment, in the case where the anode 34
included artificial graphite as the anode active material, when the
solvent of the electrolytic solution included the sulfone compound
represented by Chemical Formula 49, the cycle characteristics were
improved. It was confirmed that in this case, the content of the
sulfone compound represented by Chemical Formula 49 was within a
range from 0.01 wt % to 5 wt % both inclusive, superior
characteristics were obtained, and when the content was within a
range from 1 wt % to 5 wt % both inclusive, more specifically
within a range from 1 wt % to 2 wt % both inclusive, the
characteristics were further improved.
Examples 16-1 to 16-6
[0307] Secondary batteries were formed by the same steps as those
in Example 15-2, except that as the solvent, VC (Example 16-1), FEC
(Example 16-2), t-DFEC (Example 16-3), c-DFEC (Example 16-4), PRS
(Example 16-5) or SBAH (Example 16-6) was added. At that time, the
content of VC or the like in the solvent was 1 wt %.
Examples 16-7 and 16-8
[0308] Secondary batteries were formed by the same steps as those
in Examples 16-2 and 16-3, except that as the solvent, PC was
added. At that time, the mixture ratio of EC, DEC and PC was a
weight ratio of 20:70:10.
Comparative Examples 16-1 and 16-2
[0309] Secondary batteries were formed by the same steps as those
in Examples 16-1 and 16-2, except that the compound represented by
Chemical Formula 50(7) was not added.
[0310] When the cycle characteristics of the secondary batteries of
Examples 16-1 to 16-8 and Comparative Examples 16-1 and 16-2 were
determined, results shown in Table 16 were obtained.
TABLE-US-00016 TABLE 16 Anode active material: artificial graphite
SOLVENT DISCHARGE CAPACITY ELECTROLYTE SULFONE COMPOUND RETENTION
RATIO SALT KIND KIND WT % (%) EXAMPLE 15-2 LiPF.sub.6 EC + DEC
CHEMICAL 1 87 EXAMPLE 16-1 1 mol/kg EC + VC FORMULA 50(7) 90
EXAMPLE 16-2 DEC FEC 91 EXAMPLE 16-3 t-DFEC 92 EXAMPLE 16-4 c-DFEC
92 EXAMPLE 16-5 PRS 89 EXAMPLE 16-6 SBAH 90 EXAMPLE 16-7 EC + FEC
91 EXAMPLE 16-8 DEC + t-DFEC 92 PC COMPARATIVE LiPF.sub.6 EC + VC
-- -- 87 EXAMPLE 16-1 1 mol/kg DEC COMPARATIVE FEC 88 EXAMPLE
16-2
[0311] As shown in Table 16, in Examples 16-1 to 16-8 in which the
solvent included VC or the like, the discharge capacity retention
ratio was higher than that in Example 15-2 in which VC or the like
was not included. In this case, when FEC, t-DFEC and c-DFEC were
compared, there was a tendency that in the case where t-DFEC or
c-DFEC was included, the discharge capacity retention ratio was
higher than that in the case where FEC was included. Moreover, in
Examples 16-7 and 16-8 in which the solvent included PC, a
discharge capacity retention ratio equal to that in Examples 16-1
and 16-2 in which PC was not included was obtained, and even if PC
was included, a decline in the discharge capacity retention ratio
was not shown. In Examples 16-1 and 16-2 in which the solvent
included the compound represented by Chemical Formula 50(7), the
discharge capacity retention ratio was higher than that in
Comparative Examples 16-1 and 16-2 in which the compound
represented by Chemical Formula 50(7) was not included.
[0312] Therefore, it was confirmed that in the secondary battery
according to the embodiment, when the solvent included the cyclic
carbonate including an unsaturated bond, the cyclic carbonate
represented by Chemical Formula 21 which included a halogen, a
sultone or an acid anhydride, the cycle characteristics were
further improved, and when the solvent included propylene
carbonate, the cycle characteristics were improved. In particular,
it was confirmed that in the case where the cyclic carbonate
represented by Chemical Formula 21 which included a halogen was
used, the more the number of halogens increased, the more the cycle
characteristics were improved.
[0313] The result in the case where the solvent includes the chain
carbonate represented by Chemical Formula 20 which includes a
halogen is not shown here. However, the chain carbonate including a
halogen has the same functions as the cyclic carbonate including a
halogen, so it is obvious that even in the case where the chain
carbonate including a halogen is included, the same effects are
obtained. The same holds for the case where the chain carbonate
including a halogen and the cyclic carbonate including a halogen
are mixed, or the case where two or more kinds of the chain
carbonates and two or more kinds of the cyclic carbonates are
mixed.
Examples 17-1 and 17-2
[0314] Secondary batteries were formed by the same steps as those
in Example 15-2, except that as the electrolyte salt, lithium
tetrafluoroborate (Example 17-1) or the compound represented by
Chemical Formula 27(6) as the compound represented by Chemical
Formula 24 (Example 17-2) was added. At that time, the
concentration of lithium hexafluorophosphate in the electrolytic
solution was 0.9 mol/kg, and the concentration of lithium
tetrafluoroborate or the like was 0.1 mol/kg.
Comparative Example 17
[0315] A secondary battery was formed by the same steps as those in
Example 17-1, except that the compound represented by Chemical
Formula 50(7) was not added.
[0316] When the cycle characteristics of the secondary batteries of
Examples 17-1 and 17-2 and Comparative Example 17 were determined,
results shown in Table 17 were obtained.
TABLE-US-00017 TABLE 17 Anode active material: artificial graphite
DISCHARGE CAPACITY SOLVENT RETENTION SULFONE COMPOUND RATIO
ELECTROLYTE SALT KIND KIND WT % (%) EXAMPLE 15-2 LiPF.sub.6 EC +
CHEMICAL 1 87 1 mol/kg DEC FORMULA 50(7) EXAMPLE 17-1 LiPF.sub.6
LIBF.sub.4 89 0.9 mol/kg 0.1 mol/kg EXAMPLE 17-2 LiPF.sub.6
CHEMICAL 88 0.9 mol/kg FORMULA 27(6) 0.1 mol/kg COMPARATIVE
LiPF.sub.6 LIBF.sub.4 EC + -- -- 84 EXAMPLE 17 0.9 mol/kg 0.1
mol/kg DEC
[0317] As shown in Table 17, in Examples 17-1 and 17-2 in which the
electrolyte salt included lithium tetrafluoroborate or the like,
the discharge capacity retention ratio was higher than that in
Example 15-2 in which lithium tetrafluoroborate or the like was not
included. In Example 17-1 in which the solvent included the
compound represented by Chemical Formula 50(7), the discharge
capacity retention ratio was higher than that in Comparative
Example 17 in which the compound represented by Chemical Formula
50(7) was not included.
[0318] It was confirmed that in the secondary battery according to
the embodiment, when the electrolyte salt included lithium
tetrafluoroborate or the compound represented by Chemical Formula
24, the cycle characteristics were further improved.
[0319] The result in the case where the electrolyte salt includes
at least one kind selected from the group consisting of lithium
perchlorate and lithium hexafluoroarsenate, at least one kind
selected from the group consisting of the compounds represented by
Chemical Formulas 25 and 26, or at least one kind selected from the
group consisting of the compounds represented by Chemical Formulas
30 to 32 is not shown here. However, lithium perchlorate or the
like has the same functions as lithium tetrafluoroborate or the
like, so it is obvious that even in the case where lithium
perchlorate or the like is included, the same effects are obtained.
The same holds for the case where two or more kinds of the
above-described electrolyte salts are mixed.
Examples 18-1 to 18-7
[0320] Secondary batteries were formed by the same steps as those
in Examples 15-1 to 15-7, except that as the anode active material,
instead of artificial graphite, silicon was used to form the anode
active material layer 34B. In the case where the anode active
material layer 34B was formed, silicon was deposited on the anode
current collector 34A by an electron beam evaporation method.
Comparative Examples 18-1 to 18-4
[0321] Secondary batteries were formed by the same steps as those
in Comparative Examples 15-1 to 15-4, except that as in the case of
Examples 18-1 to 18-7, silicon was used to form the anode active
material layer 22B.
[0322] When the cycle characteristics of the secondary batteries of
Examples 18-1 to 18-7 and Comparative Examples 18-1 to 18-4 were
determined, results shown in Table 18 were obtained.
TABLE-US-00018 TABLE 18 Anode active material: silicon DIS- CHARGE
CAPAC- ITY SOLVENT RETEN- ELECTRO- SULFONE TION LYTE COMPOUND RATIO
SALT KIND KIND WT % (%) EXAMPLE LiPF.sub.6 EC + D CHEMICAL 0.01 45
18-1 1 mol/kg EC FORMULA EXAMPLE 50(7) 1 48 18-2 EXAMPLE 2 55 18-3
EXAMPLE 5 62 18-4 EXAMPLE CHEMICAL 1 58 18-5 FORMULA 50(1) EXAMPLE
CHEMICAL 1 54 18-6 FORMULA 51(6) EXAMPLE CHEMICAL 1 55 18-7 FORMULA
52(1) COM- LiPF.sub.6 EC + D -- -- 40 PARATIVE 1 mol/kg EC EXAMPLE
18-1 COM- CHEMICAL 1 38 PARATIVE FORMULA EXAMPLE 53 18-2 COM-
CHEMICAL 1 36 PARATIVE FORMULA EXAMPLE 54 18-3 COM- CHEMICAL 1 39
PARATIVE FORMULA EXAMPLE 55 18-4
[0323] As shown in Table 18, in the case where silicon was used as
the anode active material, substantially the same results as those
in Table 15 were obtained. In other words, in Examples 18-1 to 18-7
in which the solvent included the sulfone compound represented by
Chemical Formula 49 (the compound represented by Chemical Formula
50(7) or the like), the discharge capacity retention ratio was
higher than that in Comparative Examples 18-1 to 18-4. In this
case, in the case where the content of the compound represented by
Chemical Formula 50(7) in the solvent was within a range from 0.01
wt % to 5 wt % both inclusive, a high discharge capacity retention
ratio was obtained. Moreover, in the case where the sulfone
compound represented by Chemical Formula 49 (the compound
represented by Chemical Formula 50(7) or the like) was included,
the discharge capacity retention ratio was higher than that in the
case where other sulfone compounds represented by Chemical Formulas
53 to 55.
[0324] Therefore, it was confirmed that in the secondary battery
according to the embodiment, in the case where the anode 34
included silicon as the anode active material, when the solvent of
the electrolytic solution included the sulfone compound represented
by Chemical Formula 49, as in the case where artificial graphite
was included, the cycle characteristics were improved. It was
confirmed that in this case, when the content of the sulfone
compound represented by Chemical Formula 49 in the solvent was 0.01
wt % to 5 wt % both inclusive, superior characteristics were
obtained, and when the content was within a range from 1 wt % to 5
wt % both inclusive, more specifically within a range from 2 wt %
to 5 wt % both inclusive, the characteristics were further
improved.
Examples 19-1 to 19-8
[0325] Secondary batteries were formed by the same steps as those
in Examples 16-1 to 16-8, except that as in the case of Examples
18-1 to 18-7, silicon was used to form the anode active material
layer 34B.
Comparative Examples 19-1 and 19-2
[0326] Secondary batteries were formed by the same steps as those
in Comparative Examples 16-1 and 16-2, except that as in the case
of Examples 18-1 to 18-7, silicon was used to form the anode active
material layer 34B.
[0327] When the cycle characteristics of the secondary batteries of
Examples 19-1 to 19-8 and Comparative Examples 19-1 and 19-2 were
determined, results shown in Table 19 were obtained.
TABLE-US-00019 TABLE 19 Anode active material: silicon SOLVENT
DISCHARGE CAPACITY ELECTROLYTE SULFONE COMPOUND RETENTION RATIO
SALT KIND KIND WT % (%) EXAMPLE 18-2 LiPF.sub.6 EC + DEC CHEMICAL 1
48 EXAMPLE 19-1 1 mol/kg EC + VC FORMULA 50(7) 78 EXAMPLE 19-2 DEC
FEC 74 EXAMPLE 19-3 t-DFEC 82 EXAMPLE 19-4 c-DFEC 82 EXAMPLE 19-5
PRS 62 EXAMPLE 19-6 SBAH 64 EXAMPLE 19-7 EC + FEC 75 EXAMPLE 19-8
DEC + t-DFEC 83 PC COMPARATIVE LiPF.sub.6 EC + VC -- -- 68 EXAMPLE
19-1 1 mol/kg DEC COMPARATIVE FEC 60 EXAMPLE 19-2
[0328] As shown in Table 19, in the case where silicon was used as
the anode active material, the same results as those in Table 16
were obtained. In other words, in Examples 19-1 to 19-8 in which
the solvent included VC or the like, the discharge capacity
retention ratio was higher than that in Examples 18-2 in which VC
or the like was not included. In this case, in the case where
t-DFEC or c-DFEC was included, the discharge capacity retention
ratio was higher than that in the case where FEC was included, and
in the case where PC was included, a high discharge capacity
retention ratio was obtained. In Examples 19-1 and 19-2 in which
the solvent included the compound represented by Chemical Formula
50(7), the discharge capacity retention ratio was higher than that
in Comparative Examples 19-1 and 19-2 in which the compound
represented by Chemical Formula 50(7) was not included.
[0329] Therefore, it was confirmed that in the secondary battery
according to the embodiment, when the solvent included the cyclic
carbonate including an unsaturated bond, the cyclic carbonate
represented by Chemical Formula 21 which included a halogen, the
sultone or the acid anhydride, the cycle characteristics were
further improved, or when the solvent included propylene carbonate,
the cycle characteristics were improved.
Examples 20-1 and 20-2
[0330] Secondary batteries were formed by the same steps as those
in Examples 17-1 and 17-2, except that as in the case of Examples
18-1 to 18-7, silicon was used to form the anode active material
layer 34B.
Comparative Example 20
[0331] A secondary battery was formed by the same steps as those in
Comparative Example 17, except that as in the case of Examples 18-1
to 18-7, silicon was used to form the anode active material layer
34B.
[0332] When the cycle characteristics of the secondary battery of
Examples 20-1 and 20-2 and Comparative Example 20 were determined,
results shown in Table 20 were obtained.
TABLE-US-00020 TABLE 20 Anode active material: silicon DISCHARGE
CAPACITY SOLVENT RETENTION SULFONE COMPOUND RATIO ELECTROLYTE SALT
KIND KIND WT % (%) EXAMPLE 18-2 LiPF.sub.6 EC + CHEMICAL 1 48 1
mol/kg DEC FORMULA 50(7) EXAMPLE 20-1 LiPF.sub.6 LIBF.sub.4 63 0.9
mol/kg 0.1 mol/kg EXAMPLE 20-2 LiPF.sub.6 CHEMICAL 62 0.9 mol/kg
FORMULA 27(6) 0.1 mol/kg COMPARATIVE LiPF.sub.6 LIBF.sub.4 EC + --
-- 53 EXAMPLE 20 0.9 mol/kg 0.1 mol/kg DEC
[0333] As shown in Table 20, in the case where silicon was used as
the anode active material, the same results as those in Table 17
were obtained. In other words, in Examples 20-1 and 20-2 in which
the electrolyte salt included lithium tetrafluoroborate or the
like, the discharge capacity retention ratio was higher than that
in Example 18-2 in which lithium tetrafluoroborate or the like was
not included. In Example 20-1 in which the solvent included the
compound represented by Chemical Formula 50(7), the discharge
capacity retention ratio was higher than that in Comparative
Example 20 in which the compound represented by Chemical Formula
50(7) was not included.
[0334] Therefore, it was confirmed that in the secondary battery
according to the embodiment, when the electrolyte salt included
lithium tetrafluoroborate or the compound represented by Chemical
Formula 24, the cycle characteristics were further improved.
[0335] It was confirmed from the above-described results shown in
Tables 15 to 20 that in the secondary battery according to the
embodiment, when the solvent of the electrolytic solution included
the sulfone compound represented by Chemical Formula 49,
irrespective of the kind of the anode active material or the
composition of the solvent, the cycle characteristics were
improved. It was confirmed that in this case, in the case where
silicon was used as the anode active material, the rate of increase
of the discharge capacity retention ratio was larger than that in
the case where the carbon material was used as the anode active
material, so a higher effect was obtained in the case where silicon
was used. It was considered that the result was obtained, because
when silicon which was advantageous to increase the capacity was
used as the anode active material, compared to the case where the
carbon material was used, the electrolytic solution was easily
decomposed, so the decomposition inhibition effect of the
electrolytic solution was exerted pronouncedly.
[0336] Although several embodiments and examples have been
described, the embodiments and the examples may be variously
modified. For example, the application of the electrolytic solution
of the present application is not limited to batteries, and the
electrolytic solution may be applied to any other electrochemical
devices in addition to the batteries. As the other application, for
example, a capacitor or the like is cited.
[0337] Moreover, in the above-described embodiments and the
above-descried examples, the case where the electrolytic solution
or the gel electrolyte in which the polymer compound holds the
electrolytic solution is used as the electrolyte of the battery of
the present application is described. However, any other kind of
electrolyte may be used. Examples of the electrolyte include a
mixture of an ion-conducting inorganic compound such as
ion-conducting ceramic, ion-conducting glass or ionic crystal and
an electrolytic solution, a mixture of another inorganic compound
and an electrolytic solution, a mixture of the inorganic compound
and a gel electrolyte, and the like.
[0338] Moreover, in the above-described embodiments and the
above-described examples, as the battery, a lithium-ion secondary
battery in which the capacity of the anode is represented on the
basis of insertion and extraction of lithium, and a lithium metal
secondary battery in which the capacity of the anode is represented
on the basis of precipitation and dissolution of lithium are
described. However, the present application is not necessarily
limited to them. The battery of the present application is
applicable to a secondary battery in which the charge capacity of
an anode material capable of inserting and extracting lithium is
smaller than the charge capacity of a cathode, thereby the capacity
of the anode includes a capacity based on insertion and extraction
of lithium and a capacity based on precipitation and dissolution of
lithium, and is represented by the sum of them in the same
manner.
[0339] In the above-described embodiments and the above-described
examples, the case where lithium is used as an electrode reactant
is described. However, any other Group 1A element in the short form
of the periodic table of the elements such as sodium (Na) or
potassium (K), a Group 2A element in the short form of the periodic
table of the elements such as magnesium or calcium (Ca), or any
other light metal such as aluminum may be used. Also in this case,
as the anode active material, the anode material described in the
above-described embodiments may be used.
[0340] Further, in the above-described embodiments and the
above-described examples, the case where the battery has a
cylindrical type and a laminate film type and the case where a
battery device has a spirally wound configuration are described as
examples. However, the battery of the present application is
applicable to the case where a battery has any other shape such as
a prismatic type, a coin type or a button type or the case where
the battery device has any other configuration such as a laminate
configuration in the same manner. Moreover, the present application
is applicable to not only the secondary batteries but also other
kinds of batteries such as primary batteries.
[0341] In the above-described embodiments and the above-described
examples, an appropriate range, which is derived from the results
of the examples, of the content of the compounds represented by
Chemical formula 11 in the electrolytic solution or the battery is
described. However, the description does not exclude the
possibility that the content is out of the above-described range.
More specifically, the above-described appropriate range is a
specifically preferable range to obtain the effects, and as long as
the effects of the present application are obtained, the content
may be deviated from the above-described range to some extent. The
same holds for the sulfone compound represented by Chemical Formula
35 or Chemical Formula 49.
[0342] It should be understood that various changes and
modifications to the presently preferred embodiments described
herein will be apparent to those skilled in the art. Such changes
and modifications can be made without departing from the spirit and
scope of the present subject matter and without diminishing its
intended advantages. It is therefore intended that such changes and
modifications be covered by the appended claims.
* * * * *