Note: Descriptions are shown in the official language in which they were submitted.
PCT/JP2009l005370
CA 02522234 2005-10-13
1
DESCRIPTION
ELECTROLYTE COMPOSITION AND CELL
FIELD OF THE INVENTION
The present invention relates to an electrolyte
composition comprising a lithium salt compound and a
cyclic carbonate having an unsaturated group. More
particularly, the present invention relates to an
electrolyte composition which is suitable as a material
for an electrochemical device such as a battery, a
capacitor and a sensor,
BACKGROUND ARTS
As an electrolyte constituting an electrochemical
device such as a battery, a capacitor and a sensor, an
electrolyte solution or a polymer electrolyte in the form
a gel containing the electrolyte solution has hitherto
been used in view of the ionic r_onductivity. However,
the following problems are pointed out. There are a fear
of damage of an apparatus arising due to liquid leakage
of the electrolyte solution, and a problem that the
electrolyte solution reacts with a positive electrode and
a negative electrode to deteriorate electrical properties.
To the contrary, a solid electrolyte such as an inorganic
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crystalline substance, inorganic glass, and an organic
polymer substance is suggested. The organic polymer
substance is generally superior in processability and
moldability and the resulting solid electrolyte has good
flexibility and bending processability and, furthermore,
the design freedom of the device to be applied is high
and, therefore, the development thereof is expected.
However, the organic polymer substance is inferior in
ionic conductivity to other materials at present.
The discovery of ionic conductivity in a homopolymer
of ethylene oxide and an alkaline metal system causes the
active researches of a polymer solid electrolyte.
Consequently, it is believed that a polyether such as
polyethylene oxide is promising as a polymer matrix in view
of high mobility and solubility of metal cation. It is
expected that the ion migrates in an amorphous portion of
the polymer other than a crystalline portion of the polymer.
In order to decrease the crystallinity of polyethylene
oxide, various epoxides are copolymeri2ed with ethylene
oxide. US-A-4,818,699 discloses a solid electrolyte
comprising a copolymer of ethylene oxide and methyl
glycidyl ether. However, the solid electrolyte does not
always have satisfactory ionic conductivity.
JP-A-9-329114 proposes an attempt to use a polymer
solid electrolyte in which a specified alkaline metal salt
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is incorporated into a diethyleneglyCOlmethyl glycidyl
ether/ethylene oxide crosslinked material. However, this
electrolyte cannot give a practically sufficient value of
conductivity. W098/07772 filed by the present applicant
proposes a polymer solid electrolyte comprising an aprotic
organic solvent, a branched polyethylene glycol derivative
or the like in order to further improve the ionic
conductivity. However, when the lithium metal is used as
the electrode, these electrolytes react with the lithium
metal or a dendrite is precipitated on a surface of the
lithium metal so that the electrical properties are
remarkably deteriorated.
DISCLOSURE OF THE INVENTION
(Technical problems to be solved by the invention)
An object of the present invention is to pro~tide an
electrolyte composition, particularly a polymer electrolyte,
excellent in ionic conductivity and electrochemical
properties.
The present invention provides an electrolyte
composition comprising:
(1) optionally present, a polymer having an ether linkage,
(2) optionally present, an additive which comprises an
ether compound having an ethylene oxide unit,
(3) a lithium salt compound, and
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(4) a cyclic carbonate having an unsaturated group,
wherein at least one of the components (1) and (2) is
present.
In addition, the present invention provides a battery
comprising said electrolyte composition.
We discovered that the use of electrolyte composition
of the present invention can give the high-performance
battery stable to a lithium metal.
(Effects Advantageous Over Prior Arts)
The solid electrolyte composition of the present
invention is excellent in processability, moldability,
mechanical strength, softness, heat resistance and the like
and its electrochemical properties to the lithium metal are
remarkably improved. It can be applied to solid batteries
(particularly, secondary batteries) and electronic
apparatuses such as a large-capacity condenser and a
display device (e. g., an electrochromic display).
PREFERRED EMBODIMENTS OF THE INVENTION
The electrolyte composition of the present invention
contains at least one of the polymer (1) and the additive
(2). The electrolyte composition may contain both of the
polymer (1~ and the additive (2).
The ether linkage-containing polymer (1) is preferably
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a copolymer comprising a repeating unit of the formula (i)
and a repeating unit of the formula (ii), or a copolymer
comprising the repeating unit (i), the repeating unit (ii)
and a crosslinkable repeating unit of the formula (iii).
5 Further, a random copolymer is preferable.
"'~ ~2~2'0 ~" ( i )
-~- CH2 ~ H-0 -~- ( i i )
R1
wherein R1 is an alkyl group having 1 to 6 carbon atoms, a
phenyl group or -CH20-Rz
(wherein Rz is an alkyl group having 1 to 6 carbon atoms, a
phenyl group or - (-CHz-CHz-O-) a-Rz~ or -CH [CH2-O- (-CH2-CHz-O-
)b-R2~~z (wherein Rz~ is an alkyl group having 1 to 6 carbon
atoms, and a and b each is an integer of 0 to 12)),
~111~
~3
R
wherein R3 is (a) a reactive silicon group, (b) a
methylepoxy group, (c) an ethylenically unsaturated group,
or (d) a reactive group having a halogen atom.
The monomer constituting the repeating unit (i) in the
polymer (1) is ethylene oxide.
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The oxirane compound constituting the repeating unit
(ii) in the polymer (1) includes a gly~idyl ether compound
and an alkylene oxide optionally having a substituent group.
Specific examples are an oxirane compound such as propylene
oxide, methyl glycidyl ether, butyl glycidyl ether, styrene
oxide, phenyl glycidyl ether and 1,2-epoxyhexane;
ethyleneglycolmethyl glycidyl ether, diethyleneglycolmethyl
glycidyl ether, triethyleneglycolmethyl glycidyl ether,
1,3-bis(2-methoxyethoxy)propane-2-glycidyl ether and 1,3-
bis(2-(2-methoxyethoxy)ethoxy]propane-2-glycidyl ether.
The reactive functional group in the oxirane
compound forming the crosslinkable repeating unit (iii)
in the polymer (1) is preferably (a) a reactive silicon
group, (b) a methylepoxy group, (c) an ethylenically
unsaturated group, or (d) a halogen atom.
Examples of the oxirane compound having the reactive
silicon group (a) include 2-glycidoxyethyltrimethoxysilane,
3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxy-
propyltrimethoxysilane, 4-glycidoxybutylmethyltrimethoxy-
silane, 3-(1,2-epoxy)propyltrimethoxysilane, 4-(1,2-
epoxy)butyltrimethoxysilane, 5-(1,2-epoxy)pentyl-
trimethoxysilane, 1-(3,4-epoxycyclohexyl)methylmethyl-
dimethoxysilane and 2-(3,4-epoxycyclohexyl)ethyl-
trimethoxysilane_ Among them, 3-glycidoxypropyltrimethoxy-
silane and 3-glycidoxypropylmethyldimethoxysilane are
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preferable.
Examples of the oxirane compound having the
methylepoxy group (b) include 2,3-epoxypropyl-2',3'-epoxy-
2'-methylpropyl ether, ethylene glycol-2,3-epoxypropyl-
2',3'-epoxy-2'-methylpropyl ether, diethylene glycol-2,3-
epoxypropyl-2',3'-epoxy-2'-methylpropyl ether, 2-methyl-
1,2,3,4-diepoxybutane, 2-methyl-1,2,4,5-diepoxypentane, 2-
methyl-1,2,5,6-diepoxyhexane, hydroquinone-2,3-epoxypropyl-
2',3'-epoxy-2'-methylpropyl ether, and catechol-2,3-
epoxypropyl-2',3'-epoxy-2'-methylpropyl ether. Among them,
2,3-epoxypropyl-2',3'-epoxy-2'-methylpropyl ether and
ethylene glycol-2,3-epoxypropyl-2',3'-epoxy=2'-methylpropyl
ether are preferable.
Examples of the oxirane compound having the
ethyhenically unsaturated group (c) include allyl glycidyl
ether, 4-vinylcyclohexyl glycidyl ether, a-terpinyl
glycidyl ether, cyclohexenylmethyl glycidyl ether, p
vinylbenzyl glycidyl ether, allylphenyl glycidyl ether,
vinyl glycidyl ether, 3,4-epoxy-1-butene, 3,4-epoxy-1
pentene, 4,5-epoxy-2-pentene, 1,2-epoxy-5,9
cyclododecadiene, 3,4-epoxy-1-vinylcyclohexene, 1,2-epoxy
5-cyclooctene, glycidyl acrylate, glycidyl methacrylate,
glycidyl sorbinate, glycidyl cinnamate, glycidyl crotonate
and glycidyl 4-hexenoate_ Allyl glycidyl ether, glycidyl
acrylate and glycidyl methacrylate are preferable.
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Examples of the oxirane compound having the halogen
atom (d) include epibromohydrin, epiiodohydrin and
epichlorohydrin.
The polymerization method of the polymer having the
ether linkage is a polymerization method for preparing a
copolymer by a ring-opening reaction of ethylene oxide
moiety, and can be conducted in the same manner as in JP-
A-63-154736 and JP-A-62-169823.
The polymerization reaction can be conducted as
follows. The polyether copolymer can be obtained by
reacting the respective monomers at the reaction
temperature of 10 to 80°C under stirring, using a catalyst
mainly containing an organoaluminurn, a catalyst mainly
containing an organozinc, an organotin-phosphate ester
condensate catalyst and the like as a ring opening
polymerization catalyst in the presence or absence of a
solvent. The organotin-phosphate ester condensate
catalyst is particularly preferable in view of the
polymerization degree or properties of the resulting
copolymer. In the polymerization reaction, the reaction
functional group does not react and a copolymer having
the reaction functional group (1) is obtained.
The amount of the ethylene oxide constituting the
repeating unit (i) may be from 10 to 95 parts by weight,
preferably from 20 to 90 parts by weight, the amount of the
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oxirane compound constituting the repeating unit (ii) may
be from 90 to 5 parts by weight, preferably 80 tn 10 parts
by weight, the amount of the oxirane compound constituting
the crosslinkable repeating unit (iii) may be from 0 to 30
parts by weight, preferably from 0 to 20 parts by weight,
particularly from 0.1 to 20 parts by weight, based on the
polymer having the ether linkage (1) used in the
electrolyte composition of the present invention.
When the amount of the oxirane compound constituting
the crosslinkable repeating unit (iii) is at most 30 parts
by weight, the crosslinked polymer has excellent ionic
conductivity.
When the amount of ethylene oxide constituting the
repeating unit (i) is at least 10 parts by weight, the
lithium salt compound can be easily dissolved even at a low
temperature so that the ionic conductivity is high.
It is generally known that the decrease of the glass
transition temperature improves the ionic conductivity, and
it was found that the improvement effect of the ionic
conductivity is remarkably high in the case of the polymer
electrolyte composition of the present invention.
11s the molecular weight of the polymer used in the
polymer electrolyte composition, the weight-average
molecular weight is suitably within the range from 104 to
108, preferably from 105 to 10', so as to obtain excellent
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processability, moldability, mechanical strength and
flexibility.
In the crosslinking method of the copolymer (1)
wherein the reactive functional group is the reactive
5 silicon group (a), the crosslinking can be conducted by
the reaction between the reactive silicon group and water.
In order to enhance the reactivity, there may be used, as
a catalyst, organometal compounds, for example, tin
compounds such as dibutyltin dilaurate and dibutyltin
10 maleate; titanium compounds such as tetrabutyl titanate
and tetrapropyl titanate; and aluminum compounds such as
aluminum trisacetyl acetonate and aluminum trisethyl
acetoacetate; or amine compounds such as butylamine and
octylamine.
Iii the crosslinking method of the copolymer (1)
wherein the reactive functional group is the methylepoxy
group (b), for example, polyamines and acid anhydrides
can be used.
Examples of the polyamines include aliphatic
polyamines such as diethylenetriamine and dipropylene-
triamine; and aromatic polyamines such as 4,4'-diamino
diphenyl ether, diamino diphenyl sulfone, m-phenylene-
diamine and xylylenediamine. The amount of the polyamine
varies depending on the type of the polyamine, but is
normally within the range from 0_1 to 10 parts by weight,
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based on 100 parts by weight of the polymer electrolyte
composition excluding a plasticizer (i.e., the additive
(2) ) .
Examples of the acid anhydrides includes malefic
anhydride, phthalic anhydride, methylhexahydrophthalic
anhydride, tetramethylenemaleic anhydride and tetrahydro-
phthalic anhydride. The amount of the acid anhydrides
varies depending on the type of the acid anhydride, but
is normally within the range from 0.1 to 10 parts by
weight, based on 100 parts by weight of tl-ie electrolyte
composition excluding the plasticizer.
In the crosslinking, an accelerator can be used_ In
the crosslinking reaction of polyamines, examples of the
accelerator include phenol, cresol and resorcin. In the
crosslinking reaction of the acid anhydride, examples of
the accelerator include benzyldimethylamine, 2-(dimethyl-
aminoethyl)phenol and dimethylaniline. The amount of the
accelerator varies depending on the type of the
accelerator, but is normally within the range from 0.1 to
10 parts by weight, based on 100 parts by weight of the
crosslinking agent.
In the crosslinking method of the copolymer (1)
wherein the reactive functional group is the
ethylenically unsaturated group (c), a radical initiator
selected from an organic peroxide, an azo compound and
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the like, or active energy ray such as ultraviolet ray
and electron ray is used. It is also possible to use a
crosslinking agent having silicon hydride.
As the organic peroxide, there can be used those
which are normally used in the crosslinking, such as
ketone peroxide, peroxy ketal, hydroperoxide, dialkyl
peroxide, diacyl peroxide and peroxy ester. Specific
examples thereof include 1,1-bis(t-butylperoxy)-3,3,5-
trimethylcyclohexane, di-t-butyl peroxide, t-butylcumyl
peroxide, dicumyl peroxide, 2,5-dimethyl-2,5-di(t-
butylperoxy)hexane and benzoylperoxide. The amount of
the organic peroxide varies depending on the type of the
organic peroxide, but it is normally within the range
from 0.1 to 10 parts by weight, based on 100 parts by
weight of the electrolyte composition excluding the
plasticizer.
As the azo compound, there can be used those which
are normally used in the crosslinking, such as an
azonitrile compound, an azoamide compound and an
azoamidine compound, and specific examples thereof
include 2,2'-azobisisobutyronitrile, 2,2'-azobis(2-
methylbutyronitrile), 2,2'-azobis(4-methoxy-2,4-
dimethylvaleronitrile), 2,2-azobis(2-methyl-N-
phenylpropionamidine)dihydrochloride, 2,2'-azobis[2-(2-
imidazolin-2-yl)propane], 2,2'-azobis[2-methyl-N-(2-
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1. 3
hydroxyethyl)propionamide], 2,2'-azobis(2-methylpropane)
and 2,2'-azobis[2-(hydroxymethyl)propionitrile]. The
amount of the azo compound varies depending on the type
of the azo compound, but is normally within the range
from 0.1 to 10 parts by weight, based on 100 parts by
weight of the polymer electrolyte composition excluding
the plasticizer.
In the crosslinking due to radiation of activated
energy ray such as ultraviolet ray, qlycidyl acrylate
ether, glycidyl methacrylate ether and glycidyl cinnamate
ether are particularly preferable. Furthermore, as an
auxiliary scnsitizer, there can be optionally used
acetophenones such as diethoxyacetophenone, 2-hydroxy-2-
methyl-1-phenylpropan-1-one and phenylketone; benzoin;
benzoin ethers such as benzoin methyl ether;
benzophenones such as benzophenone and 4-phenylbenzo-
phenone; thioxanthones such as 2-isopropylthioxanthone
and 2,4-dimethylthioxanthone; and azides such as 3-
sulfonylazidobenzoic acid and 4-sulfonylazidobenzoic acid.
As a crosslinking accelerator, there can be
optionally used ethylene glycol diacrylate, ethylene
glycol dimethacrylate, oligoethylene glycol diacrylate,
oligoethylene glycol dimethacrylate, allyl methacrylate,
allyl acrylate, diallyl maleate, triallyl isocyanurate,
bisphenylmaleimide and malefic anhydride.
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As the compound having silicon hydride, which is
used for crosslinking the ethylenically unsaturated group
(c), a compound having at least two silicon hydrides are
used_ Particularly, a polysiloxane compound or a
polysilane compound is preferable.
Examples of the catalyst for the hydrosilylation
reaction include transition metals such as palladium and
platinum or a compound or complex thereof. ~rthermore,
a peroxide, an amine and a phosphine can also be used.
The most popular catalyst includes
dichlorobis(acetonitrile)palladium(II),
chlorotris(triphenylphosphine)rhodium(I) and
chloroplatinic acid.
In the crosslinking method of the copolymer (1)
wherein the reactive functional group is the halogen atom
(d), for example, a crosslinking agent such as polyamines,
mercaptoimidazolines, mercaptopyrimidines, thioureas and
polymercaptanes can be used. Examples of the polyamines
include triethylenetetramine and hexamethylenediamine.
2U Examples of the mercaptoimidazolines include 2-
mercaptoimidazoline and 4-methyl-2-mercaptoimidazoline.
Examples of the mercaptopyrimidines include 2-
mercaptopyrimidine and 4,6-dimethyl-2-mercaptopyrimidine.
Examples of the thioureas include ethylene thiourea and
dibutyl thiourea. Examples of the polymercaptanes
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include 2-dibutylamino-4,6-dimethylcapto-s-triazine and
2-phenylamino-4,6-dimercaptotriazine. The amount of the
crosslinking agent varies depending on the type of the
crosslinking agent, but is normally within the range from
5 0.1 to 30 parts by weight, based on 100 parts by weight
of the polymer electrolyte composition excluding the
plasticizer.
Furthermore, it is effective to add a metal compound
as an acid acceptor to the polymer solid electrolyte in
10 view of the thermal stability of the halogen-containing
polymer. Examples of the metal compound as the acid
acceptor include oxide, hydroxide, carbonate, carboxylate,
silicate, borate, and phosphate of Group I1 metals of the
Periodic Table; and oxide, basic carbonate, basic
15 carboxylate, basic phosphate, basic sulfite, or tribasic
sulfate of Group VIa metals of the Periodic Table.
Specific examples thereof include magnesia, magnesium
hydroxide, magnesium carbonate, calcium silicate, calcium
stearate, read lead and tin stearate. The amount of the
metal compound as the above acid acceptor varies
depending on the type thereof, but is normally within the
range from 0.1 to 30 parts by weight, based on 100 parts
by weight of the polymer electrolyte composition
excluding the plasticizer_
The additive (2) comprising the ether compound having
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the ethylene oxide unit acts as the plasticizer. When the
additive comprising the ether compound having the ethylene
oxide unit is added to the polymer electrolyte composition,
the crystallization of the polymer is prevented, the glass
transition Lemperature is decreased and many amorphous
phases are formed even at a low temperature to give high
ionic conductivity.
Examples of the additive (2) comprising the ether
compound having the ethylene oxide unit are preferably any
of additives of the below-mentioned formulas (iv) to (vii).
HZ-~ (-CHZ-CHZ-O-) o-R4
R6-(-0-(~12~i2 ) e~H (iv)
CHZ-O- (-~H2-~HZ-O-) d Rs
R9- (-o-~H2-c'ti~-) h-o- ~ 2 ~H2.-p- (~2-CHZ-~) f R?
~~ (~-~Z~) J~H (w)
Rl~ ( 0-~H2-CHZ ) i-O-C~2 CH2-~' ~-(~i2-Ctf2'~') g Rg
1-I2-ø- (-CHZ-CHZ-d-) k R 11
R13-(-0-CHZ-CH2-)m-O ~H-CH2~H (vi)
R14-(-0-CHZ-CHZ-)h-O-CH2 CHZ-O-(-CH2-CH2-O-)1-R12
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H -~ (-~1,1~-~CH2-U-) o_R 15
is
R 1 g-- (-0-CHZ-CH2-) r-0-0112 ~ -CHZ-O- (-CN2-G7i2-0-) p R ( v i i )
Cli2--,~ (~ ~-o-) Q R 17
wherein each of R9 to R18 is an alkyl group having 1 to 6
carbon atoms, and each of c to r is a number of 0 to 12_
The amount of the additive (2) is arbitrary, and the
total of the polymer (1) and the additive (2) is 100 parts
by weight.
The lithium salt compound (3) used in the present
invention is preferably soluble in a mixture of the
polymer (1) with the additive (2), and the cyclic
carbonate {4). In the present invention, the following
lithium salt compounds are preferably used.
Examples of the lithium salt compound include
compounds composed of a lithium ion, and an anion
selected from chlorine ion, bromine ion, iodine ion,
perchlorate ion, thiocyanate ion, tetrafluoroborate ion,
nitrate ion, As F6-, PF6 . stearylsulfonate ion,
octylsulfonate ion, dodecylbenzenesulfonate ion,
naphthalenesufonate ion, dodecylnaphthalenesulfonate ion,
7,7,8,8-tetracyano-p-quin~dimethane ion, X1S03-,
[ {X'S02) {X'S02)N]-, [ (XlSOz) (X2502) (X3502)0] and
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X1S02) (XZS02) YC]-, wherein X1, X', X3 and Y respectively
represent an electron attractive group. Preferably, X1,
XZ and X3 independently represent a perfluoroalkyl or
perfluoroaryl group having 1 to 6 carbon atoms and Y
represents a nitro group, a nitroso group, a carbonyl
group, a carboxyl group or a cyano group. X1, X2 and X3
may be the same or different.
In the present invention, the amount of the lithium
salt compound (3) is preferably from 0.1 to 1,000 parts
by weight, more preferably from 1 to 500 parts by weight,
based on 100 parts by weight of the total of the polymer
(1) and the additive (2). When this value is at most
1,000 parts by weight, the processability and moldability,
and the mechanical strength and flexibility of the
resulting solid electrolyte are high, and, furthermore,
the ionic conductivity is also high.
A flame retardant can be used when the flame
retardance is required in the case that the electrolyte
composition is used. An effective amount (for example,
at most 10 parts by weight, based on lUU parts by weight
of the total of the polymer (1) and the additive (2)) of
those selected from halide such as a brominated epoxy
compound, tetrabromobisphenol A and a chlorinated
paraffin, antimony trioxide, antimony pentaoxide,
aluminum hydroxide, magnesium hydroxide, phosphate ester,
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polyphosphate salt and zinc borate can be added as the
flame retardant.
In the unsaturated group--containing Cyclic carbonate
(4), the unsaturated group is generally a carbon-carbon
double bond.
In the case of the lithium metal battery, the cyclic
carbonate (4) reacts with the lithium metal negative
electrode to form a stable layer so that the reaction
between the electrolyte and the lithium metal, and the
growth of the dendrite are prevented.
The cyclic carbonate (4) is preferably vinylene
carbonate or a derivative thereof, or ethylene carbonate
having an unsaturated group.
In the present invention, examples of vinylene
carbonate and the derivative thereof are preferably a
compound of the below-mentioned formula (viii-1):
R19 R20
2 0 ~ =C
0 0
C=0
wherein Rlg and Rz° are hydrogen or an alkyl group having 1
to 6 carbon atoms.
In the present invention, examples of the unsaturated
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group-containing ethylene carbonate is preferably a
compound of the below-mentioned formula (viii-2):
R21 R22
\ /
C-C
(viii-2)
"~
C=O
s
wherein R21 is H or an alkyl group having 1 to 6 carbon
atoms, Rz2 is an alkenyl group having 1 to 6 carbon atoms
or -CH20Rz2' (wherein R'2'is an alkenyl group having 1 to 6
carbon atoms).
10 The use amount of the cyclic carbonate (4) is from 1
to 100 parts by weight, preferably from 5 to 80 parts by
weight, based on 100 parts by weight of the total of the
components (1) and (2) . The most suitable amount is such
that a surface of the lithium metal reacts with the cyclic
15 carbonate to form a stable layer. Excess amount of the
cyclic carbonate present in the polymer electrolyte
composition deteriorates the electrochemical properties.
A method of incorporating the cyclic carbonate (9)
is not limited, when the electrolyte compound comprising
20 the components (1), (2) and (3) is not crosslinked.
when, however, the electrolyte compound comprising
the components (1), (2) and (3) is crosslinked to be used,
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the cyclic carbonate (4) should be impregnated after the
electrolyte compound comprising the components (1), (2)
and (3) is crosslinked. The electrochemical properties
are not improved, if the cyclic carbonate (4) is
incorporated before t2ue electrolyte compound comprising
the components (1), (2) and (3) is crosslinked, and then
the crosslinking is conducted. The reason therefor seems
to be that the ethylenically unsaturated group of the
cyclic carbonate (4) is eliminated by the crosslinking.
when the electrolyte compound comprising the
components (1), (2) and (3) is crosslinked to be used, a
method of impregnating the cyclic carbonate (4) is not
particularly limited. Examples of the method include
a method of directly impregnating the cyclic carbonate
(4) into the crosslinked material of the electrolyte
compound comprising the components (1), (2) and (3);
a method of impregnating a mixture of the cyclic
carbonate (4) and the additive (2) into the crosslinked
material;
a method of impregnating a mixture of the cyclic
carbonate (4) and an organic solvent into the crosslinked
material;
a method of impregnating a mixture of the electrolyte
compomd comprising the components (1), (2) and
thereinto; and the like.
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The method for production of the polymer electrolyte
composition o.f the prPSent invention is not specifically
limited, and usually respective components may be
mechanically mixed. In the case of the polymer (1)
requiring the crosslink, the polymer electrolyte
composition can be prepared, for example, by a method of
crosslinking the copolymer after mechanically mixing the
respective components, or a method of crosslinking the
copolymer, followed by.immersing the copolymer in the
additive for a long time to perform the impregmatiom. As
means for mechanically mixing, various knead'ers, open
roll, extruder, etc_ can be optionally used.
In case that the reactive functional group is a
reactive silicon group, the amount of water used in the
crosslinking reaction is not specifically limited because
the crosslinking reaction easily occurs even in the
presence of moisture in an atmosphere. The crosslinking
can also be performed by passing through a cold water or
hot water bath for a short time, or exposing to a steam
atmosphere.
In case of the copolymer wherein the reactive
functional group is an ethylenically unsaturated group,
when using a radical initiator, the crosslinking reaction
is completed at the temperature of 10°C to 200°C within 1
minute to 20 hours. Furthermore, when using energy ray
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- 23
such as ultraviolet ray, a sensitizer is generally used.
The crosslinking reaction is normally completed at the
temperature of 10°C to 150°C within 0.1 second to 1 hour.
In case of the crosslinking agent having silicon hydride,
the crosslinking reaction is completed at the temperature
of 10°C to 180°C within 10 minutes to 10 hours.
A method of mixing the lithium salt compound (3) and
the additive (2) with the polymer (1) (that is, the
polyether copolymer) is not specifically limited. An
organic solvent can be used, if necessary. In the
production using the organic solvent, various polar
solvents such as tetrahydrofuran, acetone, acetonitrile,
dimethylformamide, dimethyl sulfoxide, dioxane, methyl
ethyl ketone and methyl isobutyl ketone may be used alone
or in combination thereof.
The polymer electrolyte composition of the present
invention is superior in mechanical strength and
flexibility, and a large area thin-film shaped solid
electrolyte can be easily obtained by utilizing the
properties of the electrolyte composition. For example,
it is possible to make a battery by using the polymer
electrolyte composition of the present invention. In
this case, examples of a positive electrode material
include lithium-manganese complex oxide, lithium
cobaltate, vanadium pentaoxide, olivin-type iron
PCT/JP2004/005370
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24
phosphate, polyacetylene, polypyrene, polyaniline,
polyphenylene, polyphenylene sulfide, polyphenylene oxide,
polypyrrole, polyfuran, and polyazulene. Examples of a
negative electrode material include an interlaminar
compound prepared by occlusion of lithium between
graphite or carbon layers, a lithium metal and a lithium-
lead alloy. By utilizing high ion conductivity, the
polymer electrolyte composition can also be used as a
diaphragm of an ion electrode of a ration such as
alkaline metal ion, Cu ion, Ca ion, and Mg ion. The
polymer electrolyte composition of the present invention
is particularly suitable as a material for
electrochemical device such as a battery, a capacitor and
a sensor.
EXAMPLES
The following Examples further illustrate the
present invention.
The composition in terms of monomer of the polyether
copolymer was determined by 1H NMR spectrum. In case of
the measurement of the molecular weight of the polyether
copolymer, a gel permeation chromatography measurement
was conducted and the molecular weight was calculated in
terms of standard polystyrene_ The gel permeation
chromatography measurement was conducted at 60°C by a
PCT/JP2004/005370
CA 02522234 2005-10-13
measuring device RID-6A manufactured by Shimadzu Corp.,
using a column manufactured by Showa Denko K.K. such as
Showdex KD-807, KD-806, KD-806M and KD-803, and
dimethylformamide (DMF) as a solvent. The glass
5 transition temperature was measured by DSC 220
manufactured by Seiko Denshi Industry Co. Ltd. and the
fusion heat was measured by a differential scanning
calorimeter DSC 7 manufactured by PerkinElmer, Inc., both
measurements being in a nitrogen atmosphere within the
10 temperature range from -100 to 80°C at a heating rate of
10°C/min. For the measurement of the electrical
conductivity 6, a sample film was previously vacuum-dried
at 30°C for 12 hours. The electrical conductivity was
measured at 10°C with sandwiched between stainless steel
15 electrodes, and the conductivity was calculated according
to the complex impedance method, using an A.C. method
(voltage: 30 mV, frequency: 10 Hz to 10 MHz).
The evaluation of the stability to a lithium metal
in the battery is determined by a lithium plating and
20 stripping cycle efficiency test. A charge/discharge
tester BTS-2004W manufactured by Nagano Ltd. was used for
the lithium plating and stripping cycle efficiency test.
A copper foil and a lithium metal as counter electrode
were used, a polymer electrolyte composition was
25 sandwiched between two electrodes to prepare a test cell.
PCT/JP2004/005370
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26
Li was plated at room temperature at the electric current
density of 0.1 mA/cm2 for 10 hours, and then Li was
stripped at the electric current density of 0.1 mA/cm2
until a terminal voltage of 2.0 V. The lithium plating
and stripping cycle efficiency was calculated according
to the following formula:
Lithium plating and stripping cycle efficiency ($) -
(time required for stripping at n cycles/
time required for plating at n cycles) x 100
Preparation Example (Production of catalyst)
Tributyltin chloride (10 g) and tributyl phosphate
(35 g) were charged in a three-necked flask equipped with
25 a stirrer, a thermometer and a distillation device, and
the mixture was heated at 250°C for 20 minutes while
stirring under a nitrogen stream and the distillate was
distilled off to obtain a solid condensate as a residue
product. In the following, this condensate was used as a
polymerization catalyst.
Polymerization Example 1 (Preparation of polymer)
After the atmosphere in a four-necked glass flask
(internal volume: 3 L) was replaced by nitrogen, the
condensate (2 g) obtained in the above Preparation
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27
Example as a catalyst, methyl glycidyl ether (100g)
having a water content adjusted to not more than 10 ppm
and n-hexane (1,000 g) as a solvent were charged in the
flask. Ethylene oxide (200 g) was gradually added with
monitoring the polymerization degree of methyl glycidyl
ether by gas chromatography. The polymerization reaction
was terminated by using methanol. A polymer was isolated
by decantation, dried at 40°C under a normal pressure for
24 hours, and then dried at 45°C under reduced pressure
for 10 hours to give 275 g of the polymer. This
copolymer had the glass transition temperature of -65°C,
the weight-average molecular weight of 1,100,000 and the
fusion heat of 7 J/g. 1H NMR spectrum analysis revealed
that the composition in terms of monomer of this
copolymer had ethylene oxide of 67 wt~ and methyl
glycidyl ether of 33 wt%.
Polymerization Example 2 (Preparation of polymer)
After the atmosphere in a four-necked glass flask
(internal volume: 3 L) was replaced by nitrogen, the
condensate (2 g) obtained in the above Preparation
Example as a catalyst, propylene oxide (100g) having a
water content adjusted to not more than 10 ppm, glycidyl
methacrylate (10 g) and n-hexane (1,000 g) as a solvent
were charged in the flask. Ethylene oxide (200 g) was
PCT/JP2004/005370
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28
gradually added with monitoring the polymerization degree
of propylene oxide by gas chromatography. The
polymerization reaction was terminated by using methanol.
A polymer was isolated by decantation, dried at 40°C
under a normal pressure for 24 hours, and then dried at
45°C under reduced pressure for 10 hours to give 283 g of
the polymer. This copolyrncr had the glass transition
temperature of -68°C, the weight-average molecular weight
of 1,700,000 and the fusion heat of 7 J/g. 1H NMR
spectrum analysis revealed that the composition in terms
of monomer of this copolymer had ethylene oxide of 67 wt~
propylene oxide 30 wt~ and glycidyl methacrylate of 3 wt%.
Polymerization Example 3 (Preparation of polymer)
After the atmosphere in a four-necked glass flask
(internal volume: 3 L) was replaced by nitrogen, the
condensate (2 g) obtained in the above Preparation
Example as a catalyst, an oxirane compound (EM) (180g) of
the below-mentioned formula (ix) having a water content
adjusted to not more than 10 ppm, allyl glycidyl ether
(20 g) and n-hexane (1,000 g) as a solvent were charged
in the flask. Ethylene oxide (120 g) was gradually added
with monitoring the polymerization degree of EM by gas
chromatography. The polymerization reaction was
terminated by using methanol. A polymer was isolated by
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29
decantation, dried at 40°C under a normal pressure for 24
hours, and then dried at 45°C under reduced pressure for
hours to give 29B g of the polymer. This copolymer
had the glass transition temperature of -72°C, the
5 weight-average molecular weight of 1,300,000 and the
fusion heat of 3 J/g. 1H NMR spectrum analysis revealed
that the composition i.n terms of monomer of this
copolymer had ethylene oxide of 37 wto, EM of 57 wt$ and
allyl glycidyl ether of 6 wt~.
2-CIf~I2-O-CH2-O-(-CH2-~H2-O-)2-~H3 (ix)
O
EM
Polymerization Example 4 (Preparation of polymer)
After the atmosphere in a four-necked glass flask
(internal volume: 3 L) was replaced by nitrogen, the
condensate (2 g) obtained in the above Preparation
Example as a catalyst, an oxirane compound (GM) (100g) of
the below-mentioned formula (x) having a water content
adjusted to not more than 10 ppm, allyl glycidyl ether
(10 g) and n-hexane (1,000 g) as a solvent were charged
in the flask. Ethylene oxide (120 g) was gradually added
with monitoring the polymerization degree of GM by gas
chromatography. The pclymerization reaction was
PCT/JP2004/005370
CA 02522234 2005-10-13
terminated by using methanol. A polymer was isolated by
decantation, dried at 40°C under a normal pressure for 24
hours, and then dried at 45°C under reduced pressure for
10 hours to give 205,g of the polymer. This copolymer
5 had the glass transition temperature of -74°C, the
weight-average molecular weight of 1,150,000 and the
fusion heat of 3 J/g. 1H NMR spectrum analysis revealed
that the composition in terms of monomer of this
copolymer had ethylene oxide of 53 wt$, GM of 43 wt~ and
10 allyl glycidyl ether of 4 wt~.
~2~ (~2~2~) 2 ~3
\ Z-CH-CH2-0-CH (x)
0
CH2 O- (~H2-CHZ-0-) 2-CH3
GI~
Example 1
15 1 g of the ethylene oxide/methyl glycidyl ether binary
copolymer having the weight.-average molecular weight of
1,100,000 obtained in Polymerization Example l, 2 g of the
additive comprising an ether compound represented by the
below-mentioned formula (iv-1) having ethylene oxide units,
20 and 0.7 g of lithium bis(trifluoromethylsulphonyl)imide
(LiTFSI) as a lithium salt compound were mixed with 50 g of
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31
acetonitrile to give a homogeneous mixture, and then the
mixture was uniformly coated on both surfaces of a porous
film having the thickness of 20 um. The coating was dried
at a reduced pressure at 30°C for 12 hours to give an
electrolyte film having a thickness of 60 ~.~.m and containing
the porous film.
N2~ t~H2~2~) 2~3
CH3 0-~CHZ-CHI ~N (iv-1)
CHZ-O-(-CH2-CH2-0-)2-CH3
Example 2
1 g of the ethylene oxide/propylene oxide/glycidyl
methacrylate ternary copolymer having the weight-average
molecular weight of 1,700,000 obtained in Polymerization
Example 2, 2 g of the additive comprising an ether compound
represented by the above-mentioned formula (iv-1) having
ethylene oxide units, 0.7 g of lithium bis(trifluoro-
methylsulphonyl)imide (LiTFSI) as a lithium salt compound,
0.015 g of benzoyl peroxide as an initiator, and 0.3 g of
ethyleneglycol diacrylate as a crosslinking accelerator
were mixed with 50 g of acetonitrile to give a homogeneous
mixture, and then the mixture was uniformly coated on a PET
PCT/JP2nn4/00537n
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32
film. The coating was dried at a reduced pressure at 30°C
for 12 hours and heated at 100°C for 3 hours under nitrogen
atmosphere to give a crosslinked electrolyte film having a
thickness of 50 ~zm.
Example 3
1 g of the ethylene oxide/EM/allyl glycidyl ether
ternary copolymer having the weight-average molecular
weight of 1,300,000 obtained in Polymerization Example 3, 2
g of the additive comprising an ether compound represented
by the below-mentioned formula (vii-1) having ethylene
oxide units, 0.8 g of lithium bis(perfluoro-
ethylsulphonyl)imide (LiBETI) as a lithium salt compound,
0.015 g of benzoyl peroxide as an initiator, and 0_3 g of
ethyleneglycol diacrylate as a crosslinking accelerator
were mixed with 50 g of acetonitrile to give a homogeneous
mixture, and then the mixture was uniformly coated on a PET
film. The coating was dried at a reduced pressure at 30°C
for 12 hours and heated at 100°C for 3 hours under nitrogen
atmosphere to give a crosslinked electrolyte film having a
thickness of 50 um.
PCT/JP2 009/005370 CA 02522234 2005-10-13
33
H2-0-CH2-CH2_(~--CH3
CH3-0-Cli2-CH2-0-CH2~-CHI-U-CHZ-CH2-0 -~H3 (vii-1)
CHZ-~-CHZ--CHZ-0-CH3
Example 4
1 g of the ethylene oxide/GM/allyl glycidyl ether
ternary copolymer having the weight-average molecular
weight of 1,300,000 obtained in Polymerization Example 4, 2
g of the additive comprising an. ether compound represented
by the above-mentioned formula (vii-1) having ethylene
oxide units, 0.8 g of lithium bis(perfluoro-
ethylsulphonyl)imide (LiBETI) as a lithium salt compound,
0.015 g of benzoyl peroxide as an initiator, and 0.3 g of
ethyleneglycol diacrylate as a crosslinking accelerator
were mixed with 50 g of acetonitrile to give a homogeneous
mixture, and then the mixture was uniformly coated on a PET
film. The coating was dried at a reduced pressure at 30°C
for 12 hours and heated at 100°C for 3 hours under nitrogen
atmosphere to give a CrOSSlinked electrolyte film having a
thickness of 50 um.
Example 5
0.02 g of the ether compound of the above-mentioned
formula (iv-1) having ethylene oxide units, which
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34
contained 5 wt$ of vinylene carbonate, was impregnated
into 0.01 g of the electrolyte film prepared in Example 1
to give an electrolyte composition which had the average
of lithium plating and stripping cycle efficiency of 83~.
The results are shown in Table 1.
Example 6
0.02 g of the ether compound of the above-mentioned
formula (vii-1) having ethylene oxide units, which
contained 10 wt~ of vinylene carbonate and 1 M lithium
bis(trifluoromethylsulphonyl)imide (LiTFSI), was
impregnated into 0.01 g of the crosslinked electrolyte
film prepared in Example 2 to give an electrolyte
composition which had the average of lithium plating and
stripping cycle efficiency of 84~. The results are shown
in Table 1.
Example 7
0.02 g of the ether compound of the above-mentioned
formula (vii-1) having ethylene oxide units, which
contained 20 wt$ of vinylene carbonate, was impregnated
into 0.01 g of the crosslinked electrolyte film prepared
in Example 3 to give an electrolyte composition which had
the average of lithium plating and stripping cycle
efficiency of 920. The results are shown in Table 1.
PCT/3P2004/005370 CA 02522234 2005-10-13
3~
Example 8
0.02 g of the ether compound of the above-mentioned
formula (vii-1) having ethylene oxide units, which
S contained 40 wt~ of vi-nylene carbonate, was impregnated
into 0.01 g of the crosslinked electrolyte film prepared
in Example 3 to give an electrolyte composition which had
the average of lithium plating and stripping cycle
efficiency of 91$. The results are shown in Table 1.
Example 9
0.02 g of the ether compound of the above-mentioned
formula (vii-1) having ethylene oxide units, which
contained 60 wt~ of vinylene carbonate, was impregnated
into 0.01 g of the crosslinked electrolyte film prepared
in Example 4 to give an electrolyte composition which had
the average of lithium plating and stripping cycle
efficiency of 91~. The results are shown in Table 1.
Comparative Example 1
0.02 g of the ether compound of the above-mentioned
formula (vii-1) having ethylene oxide units, which did
not contain vinylene carbonate, was impregnated into 0.01
g of the electrolyte film prepared in Example 2 to give
an electrolyte composition which had the average of
PCT/JP2Q04/005370
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36
lithium plating and stripping cycle efficiency of 62~.
The results are shown in Table 1_
Comparative Example 2
1 g of the ethylene oxide/EM/allyl glycidyl ether
ternary copolymer having the weight-average molecular
weight of 1,300,000 obtained in Polymerization Example 3, 2
g of the additive comprising an ether compound represented
by the above-mentioned formula (iv-1) having ethylene oxide
units, 0.7 g of lit2iium bis(trifluoromethylsulphonyl)imide
(LiTFSI) as a lithium salt compound, 0.015 g of benzoyl
peroxide as an initiator, 0.3 g of ethyleneglycol
diacrylate as a crosslinking accelerator, and 20 wt~, based
on an electrolyte, of vinylidene carbonate were mixed with
1~ 50 g of acetonitrile to give a homogeneous mixture, and
then the mixture was uniformly coated on a PET film. The
coating was dried at a reduced pressure at 30°C for 12
hours and heated at 100°C for 3 hours under nitrogen
atmosphere to give a crosslinked electrolyte composition
having a thickness of 50 um. The average value of a
lithium plating and stripping cycle efficiency of the
crosslinked electrolyte composition was 60~. The results
are shown in Table 1.
Comparative Example 3
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PCT/JP2004/005370
37
1 g of the ethylene oxide/GM/allyl glycidyh ether
ternary copolymer having the weight-average molecular
weight of 1,300,000 obtained in Polymerization Example 4, 2
g of the additive comprising an ether compound represented
by the above-mentioned formula (vii-1) having ethylene
oxide units, 0.8 g of lithium bis(perfluoro-
ethylsulphonyl)imide (LiBETI) as a lithium salt compound,
0.015 g of benzoyl peroxide as an initiator, and 0.3 g of
ethyleneglycol diacrylate as a crosslinking accelerator,
and 5o wt~, based on an electrolyte, of vinylidene
carbonate were mixed with 50 g of acetonitrile to give a
homogeneous mixture, and then the mixture was uniformly
coated on a PET film. The coating was dried at a reduced
pressure at 30°C for 12 hours and heated at 100°C for 3
Z5 hours under nitrogen atmosphere to give a crosslinked
electrolyte film having a thickness of 55 um. The average
value of a lithium plating and stripping cycle efficiency
of the crosslinked electrolyte composition was 67%. The
results are shown in Table 1.
Comparative Example 4
0.02 g of the ether compound of the above-mentioned
formula (vii-1) having ethylene oxide units, which
contained 120% o~ vinylene carbonate, was impregnated
into 0.01 g of the crosslinked electrolyte film prepared
PCT/JP2004/005370 CA 02522234 2005-10-13
38
in Example 2 to give an electrolyte composition which had
the average of lithium plating and stripping cycle
efficiency of 71%. The results are shown in Table 1.
Table
1
Vinylene Lithium stripping cycle
plating
and
carbonate efficiency
amount (wt%)
First Maximum(o) Average($)
time (%)
Ex. 5 5 80 85 83
Ex. 6 10 83 86 84
Ex 7 2 U 91 93 92
.
Ex. 8 40 90 93 91
Ex. 9 60 90 92 91
C. Ex. 1 0 46 65 62
C. Ex. 2 20 49 63 60
C. Ex. 3 50 50 71 67
C. Ex. 4 120 36 79 71
The average value was calculated from lithium plating and
stripping cycle efficiencies until 20th cycle.
Example 10
By using the electrolyte composition obtained in
Example 6 as an electrolyte, a lithium metal foil as a
negative electrode and lithium cobaltate (LiCo02) as a
positive electrode active material, a secondary battery
25 was prepared.
Lithium cobaltate was prepared by mixing
predetermined amounts of lithium carbonate and cobalt
carbonate powder and then calcining the mixture at 900°C
PCT/JP2004/005370
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39
for 5 hours. The calcined mixture was ground, and then 5
parts by weight of acetylene black, 10 parts by weight of
the polymer obtained in Polymerization Example 2 and 5
parts by weight of lithium bis(trifluoromethylsulphonyl)-
imide (LiTFSI) were added to 85 parts by weight of
resultant lithium cobaltate, mixed with rolls and press-
molded under a pressure of 30 MPa to give a film which
was a positive electrode of the battery.
The electrolyte composition obtained in Example 6
was sandwiched between the lithium metal foil and the
positive electrode plate, and the charge/discharge
characteristics of the resulting battery were examined at
room temperature with applying a pressure of 1 MPa so
that the interfaces were brought into intimate contact
with each other. The charge was conducted at an upper
limit voltage of 4.2 V under a constant current and
voltage condition, and the discharge was conducted under
a constant current. The discharge current density was
0.1 mA/cm2 and the charge was conducted at 0.1 mA/em2. A
discharge capacity after 100 cycles of charge-discharge
was 90% of an initial capacity.
Example 11
A secondary battery was produced by using the
electrolyte composition obtained in Example 7, a lithium
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PCT/JP2004/005370
metal foil as a negative electrode, and the positive
electrode prepared in Example 10. The charge-discharge
properties were examined in the same manner. A discharge
capacity after 100 cycles of charge-discharge was 91~ of
5 an initial capacity.
Comparative Example 5
A secondary battery was produced by using the
electrolyte composition obtained in Comparative Example 1,
10 a lithium metal foil as a negative electrode, and the
positive electrode prepared in Example 10. The charge-
discharge properties were examined in the same manner. A
discharge capacity after 100 cycles of charge-discharge
was 80~ of an initial capacity.
Comparative Example 6
A secondary battery was produced by using the
electrolyte composition obtained in Comparative Example 3,
a lithium metal fo~7 as a negative electrode, and the
positive electrode prepared in Example 10. The charge-
discharge properties were examined in the same manner. A
discharge capacity after 100 cycles of charge-discharge
was 78~ of an initial capacity.
Example 12
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41
Vinylene carbonate (0.004 g, 3 wt~) and an ether
compound of the below-mentioned formula (iv-1) having
ethylene oxide units (0.116 g, 97 wt$), and lithium
bis(perfluoroethylsulphonyl)imide (LiBETI) (0.08 g) were
used to give an electrolyte, which had the average of the
lithium plating and stripping cycle efficiency of 86~. The
results are shown in Table 2.
H2~ ~~H2~2~~ 2~3
CH3-0-CHZ-i;H2 -~0- ~ H ( i v- I )
CIi2-O- (-CH2-CH2-0-) 2-CH3
Example 13
The same manner as in Example 12 was repeated to give
an electrolyte except that vinylene carbonate (0.006 g, S
wt$) and the ether compound of the above-mentioned formula
(iv-1) having ethylene oxide units (0.114 g, 95 wt$) were
used. The electrolyte had the average of the lithium
plating and stripping cycle efficiency of 91$. The results
are shown in Table 2.
Example 14
The same manner as in Example 12 was repeated to give
PCT/JP2 004/005370
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92
an electrolyte except that vinylene carbonate (0.012 g, 10
wt%) and the ether compound of the above-mentioned formula
(iv-1) having ethylene oxide units (0.108 g, 90 wt~) were
used. The electrolyte had the average of the lithium
plating and stripping cycle efficiency of 92~. The results
are shown in Table 2.
Example 15
Vinylene carbonate (0.014 g, 10 wtg) and an ether
compound of the below-mentioned formula (vii-1) having
ethylene oxide units (0.1268, 90 wt~), and lithium
bis(trifluoromethylsulphonyl)imide (LiTFSI) (0.06 g) were
used to give an electrolyte, which had the average of the
lithium plating and stripping cycle efficiency of 92~. The
IS results are shown in Table 2.
~H2-4-CH2-CH2-4-CH3
CH3-0-Cli2-CH2-0-CHZ ~-CHZ-O-CH2-CH2-0 -CH3 (vii-1)
CHZ-0-CH2-CH2-o--CH3
Example 16
The same manner as in Example 12 was repeated to give
an electrolyte except that Vinylene carbonate (0.024 g, 20
wt$) and the ether compound of the above-mentioned formula
PCT/JP2 004/005370 CA 02522234 2005-10-13
43
(vii-1) having ethylene oxide units (0.096 g, 80 wt%) were
used. The electrolyte had the average of the lithium
plating and stripping cycle efficiency of 91$. The results
are shown in Table 2.
Example 17
The same manner as in Example 12 was repeated to give
an electrolyte except that vinylene carbonate (0.060 g, 50
wt%) and the ether compound of the above-mentioned formula
(vii-1) having ethylene oxide units (0.060 g, 50 wt%) were
used. The electrolyte had the average of the lithium
plating and stripping cycle efficiency of 91°a. The results
are shown in Table 2.
Example 1B
The same manner as in Example 12 was repeated to give
an electrolyte except that vinylene carbonate (0.096 g, 80
wt%) and the ether compound of the above-mentioned formula
(vii-1) having ethylene oxide uW is (0.024 g, 20 wt%) were
used. The electrolyte had the average of the lithium
plating and stripping cycle efficiency of 88%. The results
are shown in Table 2.
Comparative Example 7
An electrolyte containing the ether compound of the
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44
above-mentioned formula (iv-1) having ethylene oxide units
(0_12 g) and LiBETI (0.08 g) had the average of the lithium
plating and stripping cycle efficiency of 71$. The results
are shown in Table 2.
Comparative Example 8
An electrolyte containing the ether compound of the
above-mentioned formula (vii-1) having ethylene oxide units
(0.14 g) and LiTFSI (0.06 g) had the average of the lithium
plating and stripping cycle efficiency of 54$. The results
are shown in Table 2.
Table 2
Vinylene Lithium Lithium
carbonate salt plating
and
stri ping
c cle
efficienc
amount compound Initial Maximum Average
(wt$) ($) ($) ($)
Ex. 12 3 LiBETI 82 90 86
Ex. 13 5 LiBETI 83 92 91
Ex. 14 10 LiBETI 85 94 92
Ex. 15 10 LiTFSI 86 94 92
Ex. 16 20 LiBETI 82 93 91
Ex. 17 50 LiBETI 83 94 91
Ex. 18 80 LiBETI 88 95 88
Com. Ex. 0 LiBETI 67 78 71
7
Com. Ex. 0 LiTFSI 55 64 54
8 I
The average value was calculated from lithium plating and
stripping cycle efficiencies until 20th cycle.
Example 19
PCT/JP2 004/005370
CA 02522234 2005-10-13
By using a porous separator (E25MMS manufactured by
Tonen Tapyrus Co., Ltd., thickness: 25 um, porosity: 38%)
impregnated with the electrolyte obtained in Example 13,
a lithium metal foil as a negative electrode and lithium
5 cobaltate as a positive electrode active material, a
secondary battery was prepared.
Lithium cobaltate was prepared by mixing
predetermined amounts of lithium carbonate and cobalt
carbonate powder and then calcining the mixture at 900°C
10 for 5 hours. The calcined mixture was ground, and then 4
parts by weight of acetylene black and 6 parts by weight
of polyvinylidene fluoride were added to 90 parts by
weight of resultant lithium cobaltate, mixed with rolls
and press-molded under a pressure of 30 MPa to give a
15 film which was a positive electrode of the battery.
The porous separator impregnated with the
electrolyte obtained in Example 13 was sandwiched between
the lithium metal foil and the positive electrode plate,
and the charge/discharge characteristics of the resulting
20 battery were examined at 2S°C with applying a pressure of
1 MPa so that the interfaces were brought into intimate
contact with each other. The charge was conducted at a
current density of 0.1 mA/cm2 and an upper limit voltage
of 4.2 V under a constant current and voltage condition,
25 and the discharge was conducted at a current density of
PCT/JP2004/005370
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46
0.1 mA/cm2 under a constant current. A discharge capacity
after 100 cycles of charge-discharge was 85$ of an
initial capacity.
Example 20
A secondary battery was prepared by using a porous
separator impregnated with the electrolyte prepared in
Example 15, a lithium metal foil as a negative electrode,
and the positive electrode prepared in Example 19. The
charge/discharge properties were examined as in Example
19. A discharge capacity after 100 cycles of charge-
discharge was 88$ of an initial capacity.
Comparative Example 9
A secondary battery was prepared by using a porous
separator impregnated with the electrolyte prepared in
Comparative Example 7, a lithium metal foil as a negative
electrode, and the. positive electrode prepared in Example
19. The charge/discharge properties were examined as in
Example 19. A discharge capacity after 100 cycles of
charge-discharge was 69$ of an initial capacity.
Comparative Example 10
A secondary battery was prepared by using a porous
separator impregnated with the electrolyte prepared in
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PCT/JP2004/005370
47
Comparative Example 8, a lithium metal foil as a negative
electrode, and the positive electrode prepared in Example
19. The charge/discharge properties were examined as in
Example 19. A discharge capacity after 100 cycles of
charge-discharge was 43~ of an initial capacity.
Example 21
1 g of the ethylene oxide/methyl glycidyl ether binary
copolymer having the weight-average molecular weight of
1,100,000 obtained in Polymerization Example 1, 2 g of the
additive comprising an ether compound represented by the
below-mentioned formula (iv-1) having ethylene oxide units,
and 0.7 g of lithium bis(trifluoromethylsulphonyl)imide
(LiTFSI) as a lithium salt compound were mixed with 50 g of
acetonitrile to give a homogeneous mixture, and then the
mixture was uniformly coated on both surfaces of a porous
film having the thickness of 20 ~.un. The coating was dried
at a reduced pressure at 30°C for 12 hours to give an
electrolyte film having a thickness of 60 um and containing
the porous film.
H2-0- (-CH2-Gli2-0-) 2-CH3
CH3 D-CH2-~i2
(iv-1)
~2~ (~H2~2~~ 2~3
CA 02522234 2005-10-13
PCT/,7P2004/0053'7(7
48
Example 22
1 g of the ethylene oxide/propylene oxide/glycidyl
methacrylate ternary copolymer having the weight-average
molecular weight of 1,700,000 obtained in Polymerization
Example 2, 2 g of the additive comprising an ether compound
represented by the above-mentioned formula (iv-1) having
ethylene oxide units, 0.7 g of LiTFSI as a lithium salt
compound, 0.015 g of benzoyl peroxide as an initiator, and
0.3 g of ethyleneglycol diacrylate as a crosslinking
accelerator were mixed with 50 g of acetonitrile to give a
homogeneous mixture, and then the mixture was uniformly
coated on a polyethylene terephthalate resin (PET) film.
The coating was dried at a reduced pressure at 30°C for 12
hours and heated at 100°C for 3 hours under nitrogen
atmosphere to give a crosslinked electrolyte film having a
thickness of 50 ~.un.
Example ~3
1 g of the ethylene oxide/EM/a11y1 glycidyl ether
ternary copolymer having the weight-average molecular
weight of 1,300,000 obtained in Polymerization Example 3, 2
g of the additive comprising an ether compound represented
by the below-mentioned formula (vii-1) having ethylene
oxide units, 0_8 g of lithium bis(perfluoro-
PCT/JP2004/005370
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49
ethylsulphonyl)imide (LiBETI) as a lithium salt compound,
0.015 g n.f ben~oyl peroxide as an initiator, and 0.3 g of
ethyleneglycol diacrylate as a crosslinking accelerator
were mixed with 50 g of acetonitrile to give a homogeneous
mixture, and then the mixture was uniformly coated on a PET
film. The coating was dried at a reduced pressure at 30°C
for 12 hours and heated at 100°C for 3 hours under nitrogen
atmosphere to give a crosslinked electrolyte film having a
thickness of 50 ~.zm.
~H2-U-CH2-CHZ-0-~H3
CH3 0-CHZ-CH2-0-CH2~-Cfi2-0-CH2-CHZ-0 -CH3 (vii-1)
CHZ-fl-CHZ-CH2-0-CH3
Example 24
1 g of the ethylene oxide/GM/allyl glycidyl ether
ternary copolymer having the weight-average molecular
weight of 1,300,000 obtained in Polymerization Example 4, 2
g of the additive comprising an ether compound represented
by the above-mentioned formula (vii-1) having ethylene
oxide units, 0.8 g of LiBETI as a lithium salt compound,
0.05 g of lithium borofluoride (LiBF4), 0.015 g of benzoyl
peroxide as an initiator, and 0.3 g of ethyleneglycol
diacrylate as a crosslinking accelerator were mixed with 50
PCT/JPZ 004/005370 CA 02522234 2005-10-13
g of acetonitrile to give a homogeneous mixture, and then
the mixture was uniformly coated on a PET film. The
coating was dried at a reduced pressure at 30°C for 12
hours and heated at 100°C for 3 hours under nitrogen
5 atmosphere t~ give a crosslinked electrolyte film having a
thickness of 50 um.
Example 25
0.02 g of the ether compound of the above-mentioned
10 formula (iv-1) having ethylene oxide units, which
contained 6 wt~ of vinylethylene carbonate, was
impregnated into 0.01 g of the electrolyte film prepared
in Example 21 to give a polymer electrolyte composition
which had the average of lithium plating and stripping
15 cycle efficiency of 750. The results are shown in Table
3.
Example 26
0.02 g of the ether compound of the above-mentioned
20 formula (vii-1) having ethylene oxide units, which
contained 12 wt~ of vinylethylene carbonate and 1 mol/kg
LiTFSI, was impregnated into 0.01 g of the crosslinked
electrolyte film excluding the PET film prepared in
Example 22 to give a polymer electrolyte composition
25 which had the average of lithium plating and stripping
PCT/JP2004/005370
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51
cycle efficiency of 82$. The results are shown in Table
3.
Example 27
0.02 g of the ether compound of the above-mentioned
formula (vii-1) having ethylene oxide units, which
contained 18 wt$ of vinylethylene carbonate, was
impregnated into 0.01 g of the crosslinked~electrolyte
film prepared in Example 23 to give a polymer electrolyte
composition which had the average of lithium plating and
stripping cycle efficiency of 91~. The results are shown
in Table 3.
Example 28
0,02 g of the ether compound of the above-mentioned
formula (vii-1) having ethylene oxide units, which
contained 20 wto of vinylethylene carbonate, was
impregnated into 0.01 g of the crosslinked electrolyte
film prepared in Example 24 to give a polymer electrolyte
composition which had the average of lithium plating and
stripping cycle efficiency of 93$. The results are shown
in Table 3.
Example 29
0.02 g of the ether compound of the above-mentioned
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52
formula (vii-1) having ethylene oxide units, which
contained 50 wt$ of vinylethylene carbonate, was
impregnated into 0.01 g of the crosslinked electrolyte
film prepared in Example 24 to give a polymer electrolyte
composition which had the average of lithium plating and
stripping cycle efficiency of 90$. The results are shown
in Table 3.
Comparative Example 11
0.02 g of the ether compound of the above-mentioned
formula (vii-1) having ethylene oxide units, which did
not contain vinylethylene carbonate, was impregnated into
0.01 g of the crosslinked electrolyte film prepared in
Example 22 to give a polymer electrolyte composition
which had the average of lithium plating and stripping
cycle efficiency of 62$. The results are shown in Table
3.
Comparative Example 12
0.02 g of the ether compound of the above-mentioned
formula (vii-1) having ethylene oxide units, which
contained 20 wt~ of ethylene carbonate, was impregnated
into 0.01 g of the crosslinked electrolyte film prepared
in Example 23 to give a polymer electrolyte composition
which had the average of lithium plating and stripping
PCT/JP2 004/005370 CA 02522234 2005-10-13
53
cycle efficiency of 58~. The results are shown in Table
3.
Comparative Example 13
0.02 g of the ether compound of the above-mentioned
formula (vii-1) having ethylene oxide units, which
contained 20 wt~ of propylene carbonate, was impregnated
into 0.02 g of the crosslinked electrolyte film prepared
in Example 23 to give a polymer electrolyte composition
which had the average of lithium plating and stripping
cycle efficiency of 380. The results are shown in Table
3.
Comparative Example 14
O.U2 g of the ether compound of the above-mentioned
formula (vii-1) having ethylene oxide units, which
contained 120 wt~ of vinylethylene carbonate, was
impregnated into 0.01 g of the crosslinked electrolyte
film prepared in Example 22 to give a polymer electrolyte
composition which had the average of lithium plating and
stripping cycle efficiency of 65$. The results are shown
in Table 3.
PCT/JP2009/(705370
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54
Table 3
Vinylethylene Lithium
carbonate plating
and
stripping
cycle
efficient
Amount (wt%) Initial Maximum Average
(~)
Ex. 25 6 68 80 75
Ex. 26 12 80 84 82
Ex. 27 18 89 93 91
Ex. 28 20 91 94 93
Ex. 29 50 88 92 90
Com. Ex. 0 46 65 62
11
Com. Ex. 0 46 61 58
12
Com. Ex. 0 26 58 38
13
Com. Ex. 120 55 71 65
14
The average value was calculated from lithium plating and
stripping cycle efficiencies until 20th cycle.
Example 30
By using the polymer electrolyte composition
obtained in Example 26, a lithium metal foil as a
negative electrode and lithium cobaltate (LiCoOZ) as a
positive electrode active material, a secondary battery
was prepared.
Lithium cobaltate was prepared by mixir~g
predetermined amounts of lithium carbonate and cobalt
carbonate powder and then calcining the mixture at 900°C
for 5 hours. The calcined mixture was ground, and then 5
parts by weight of acetylene black, 10 parts by weight of
the polymer obtained in Polymerization Example 2 and 5
parts by weight of LiTFSI were added to 85 parts by
weight of resultant lithium cobaltate, mixed with rills
and press-molded under a pressure of 30 MPa to give a
PCT/JP2004/005370
CA 02522234 2005-10-13
film which was a positive electrode of the battery.
The polymer electrolyte composition obtained in
Example 26 was sandwiched between the lithium metal foil
and the positive electrode plate, and the
5 charge/discharge characteristics of the resulting battery
were examined at room temperature with applying a
pressure of 1 MPa so that the interfaces were brought
into intimate contact with each other. The charge was
conducted at a constant current and a constant voltage of
10 at most 4.2 V, and the discharge was conducted at a
constant current. The discharge current was 0.1 mA/cm2
and the charge was conducted at 0.1 mA/cm2. A discharge
capacity after 100 cycles of charge-discharge was 90~ of
an initial capacity.
Example 31
A secondary battery was produced by using the
polymer electrolyte composition obtained in Example 28, a
lithium metal foil as a negative electrode, and the
positive electrode prepared in Example 30. The charge-
discharge properties were examined in the same manner. A
discharge capacity after 100 cycles of charge-discharge
was 91~ of an initial capacity.
Comparative Example 15
PCT/JP2 004/005370
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56
A secondary battery was produced by using the
polymer electrolyte composition obtained in Comparative
Example 11, a lithium metal foil as a negative electrode,
and the positive electrode prepared in Example 30. The
charge-discharge properties were examined in the same
manner. A discharge capacity after 100 cycles of charge-
discharge was 80$ of an initial capacity.
Example 32
IO 0.116 g (97 wt~) of the ether compound of the below-
mentioned formula (iv-2) having ethylene oxide units,
which contained 0.004 g (3 wt$) of vinylethylene
carbonate, and lithium bis(perfluoroethylsulphonyl)imide
(LiHETI) were used to give an electrolyte which had the
average of lithium plating and stripping cycle efficiency
of 82~. The results are shown in Table 4.
H2-8- C-CH2-CH2-0-)3 -CH3
CH3-0-~i2-CH2 -0-~ H
CH2--o- <-CH2~H2-0-)3 -CH3
Example 33
An electrolyte was prepared in the same manner as in
Example 32 except that 0.114 g (95 wt~) of the ether
PCT/3P2004/0053~0
CA 02522234 2005-10-13
57
compound of the above-mentioned formula (iv-2) having
ethylene oxide units and 0_006 g (5 wt$) of vinylethylene
carbonate were used. The electrolyte had the average of
lithium plating and stripping cycle. efficiency of 88$.
The results are shown in Table 4.
Example 34
An electrolyte was prepared in the same manner as in
Example 32 except that 0.108 g (90 wt$) of the ether
compound of the above-mentioned formula (iv-2) having
ethylene oxide units and 0.012 g (10 wt$) of
vinylethylene carbonate were used. The electrolyte had
the average of lithium plating and stripping cycle
efficiency of 93$. The results are shown in Table 4.
Example 35
0.126 g (90 wt$) of the ether compound of the below-
mentioned formula (vii-1) having ethylene oxide units,
0.014 g (10 wt$) of vinylethylene carbonate, 0.054 g of
lithium bis(trifluoromethylsulphonyl)imide (LiTFSI) and
0.001 g of lithium borofluoride (LiBFq) were used to give
an electrolyte which had the average of lithium plating
and stripping cycle efficiency of 90$. The results are
shown in Table 4.
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58
~HZ-0-CH2-CHZ-0-CH3
CH3-0-CIi2-CHZ-fl-CH2 -CHZ-0-CH2-CH2-0 -CH3 (v i i-1)
CHZ-O-CHZ-CH2-0-CH3
Example 36
An electrolyte was prepared in the same manner as in
Example 35 except that 0.096 g (80 wt~) of the ether
compound of the above-mentioned formula (vii-1) having
ethylene oxide units, and 0.024 g (20 wt$) of
vinylethylene carbonate were used. The electrolyte had
the average of lithium plating and stripping cycle
efficiency of 89$. The results are shown in Table 4.
Example 37
An electrolyte was prepared in the same manner as in
Example 32 cxccpt that 0.060 g (50 wt~) of the ether
compound of the above-mentioned formula (vii-1) having
ethylene oxide units, and 0.060 g (50 wt~) of
vinylethylene carbonate were used. The electrolyte had
the average of lithium plating and stripping cycle
efficiency of 92°s. The results are shown in Table 4.
PC:T/JP2n04/ 005370
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59
Table 4
Vinyl- Lithium Lithium
plating
and
ethylene salt stripping
cycle
efficiency
carbonate compound Initial Maximum Average
amount ( m o 1 / k ( $ ) ( ~; ) ( ~ )
g )
(wt$)
Ex. 3 LiBETI=1.0 80 88 82
32
Ex. 5 LiBETI=1.0 82 92 88
33
Ex. 10 LiBETI=1.0 87 96 93
34
Ex . 1 0 L i T F S I 84 93 90
= 1 . 0
3 5 LiBF9=0 . 05
Ex. 20 LiTFSI=1. 0 82 93 89
3 6 LiBFq=0 . 05
E 50 LiBETI=1 . 85 94 92
. 0
~ I ~ ~ ~
~
The average value was calculated from lithium plating and
stripping cycle efficiencies until 20th cycle.