JPH05325986A - Gel-state electrolyte - Google Patents

Abstract

PURPOSE:To provide a gel-state electrolyte having high ionic conductivity further with good shape holdability by using a mixture of nonaqueous solvent, electrolytic salt and cross-linked vinyl polymer. CONSTITUTION:A mixture of nonaqueous solvent of carbonate solvent, lactone solvent, pyrolidone solvent, etc., electrolytic salt of metal salt, ammonium salt, etc., and a cross-linked vinyl polymer is used as a gel-state electrolyte. The gel-state electrolyte thus obtained is provided with high ionic conductivity further with a good electrochemical characteristic and shape holding characteristic at a high temperature, and when used for an electrochemical element of battery, capacitor, etc., an effect of the electrolyte is displayed. Further, the cross-linked vinyl polymer is preferable to contain 0.01 to 10wt.% monomer, having two or more vinyl groups, as a constitutional unit.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a gel electrolyte.
More specifically, the present invention relates to a gel electrolyte used in electrochemical devices such as batteries and capacitors.

[0002]

2. Description of the Related Art Heretofore, known are gel electrolytes containing a lithium ion conductive gel electrolyte (JP-A-62-219468) and polyalkyl methacrylate (JP-A-57-101352). Has been.

[0003]

In recent years, capacitors,
There is a strong demand for non-fluidization of electrochemical devices such as batteries, electrochromic devices and sensors. By making the electrolyte non-fluidic, not only is it smaller and more reliable,
High functionality is possible by integrating and stacking electrochemical elements. However, the conventional gel electrolyte has a problem in that it has insufficient electrochemical characteristics and ionic conductivity, and further has insufficient shape retention especially at high temperatures.

[0004]

The present inventors have arrived at the present invention as a result of diligent studies to obtain a gel electrolyte solution that solves the above problems. That is, the present invention is a non-aqueous solvent (A),
It is a gel electrolyte characterized by comprising a mixture of an electrolyte salt (B) and a crosslinked vinyl polymer (C).

In the present invention, the non-aqueous solvent (A) is
Carbonate-based solvents (propylene carbonate, ethylene carbonate, styrene carbonate, etc.), lactone-based solvents (γ-butyrolactone, γ-valerolactone, δ
-Valerolactone, 3-methyl-1,3-oxazolidin-2-one, 3-ethyl-1,3-oxazolidine-
2-one), pyrrolidone-based solvent (N-methylpyrrolidone, N-ethylpyrrolidone, etc.), amide-based solvent (N-methylformamide, N, N-dimethylformamide, N)
-Methylacetamide, etc.), furan-based solvents (furan, tetrahydrofuran, 2-methyltetrahydrofuran, etc.), ether-based solvents (dibutyl ether, 1,2-dimethoxyethane, methyl diglyme, butyl diglyme, ethyl cellosolve, butyl carbitol, etc. ), Dioxolane-based solvent (1,3-dioxolane, 4-methyl-
1,3-dioxolan-2-one, etc., alcohol solvents (ethylene glycol, methyl cellosolve, propylene glycol, 1,4-butanediol, glycerin,
Polyoxyalkylene polyol, cyclohexanediol, etc.), nitrile solvents (acetonitrile, 3-methoxypropionitrile, etc.) and imidazolidinone solvents (1,3-dimethyl-2-imidazolidinone, etc.), sulfolane solvents (sulfolane) , 3-methylsulfolane, etc.) and the like. You may mix and use these. Among these non-aqueous solvents, carbonate solvents, lactone solvents, ether solvents and furan solvents are preferable.

In the present invention, as the electrolyte salt (B),
Metal salts and ammonium salts are mentioned. Examples of the metal salt include salts of group I or group II metals, and among these, salts of Li, Na and K having a small cation radius are preferable. Examples of anions that compose these metal salts include halogen ions (F, Cl, Br, I), thiocyanate ions, perchlorate ions, trifluoromethanesulfonate ions and fluoroborate ions. Among the anions constituting the metal salt, preferred are thiocyanate ion, perchlorate ion, trifluoromethanesulfonate ion and fluoroborate ion.

Examples of the ammonium salt include 1 to 4 quaternary ammonium salts, and among these, preferred are quaternary ammonium salts. Specific examples of amine components constituting ammonium salts include tetraalkylammonium (tetramethylammonium, tetraethylammonium, tetrapropylammonium, tetrabutylammonium, dimethyldiethylammonium, etc.), pyridinium (1-methylpyridinium, 1-ethylpyridinium,
1,3-diethylpyridinium), and tetraalkylammonium is preferable. Examples of the acid component that constitutes the ammonium salt include carboxylic acid (adipic acid, phthalic acid, azelaic acid, etc.), phosphoric acid, boric acid, sulfonic acid (aryl sulfonic acid, etc.), borofluoric acid, and the like. Phosphoric acid and boric acid are preferred.

In the present invention, the crosslinked vinyl polymer (C) comprises a monomer (c1) having two or more vinyl groups and a monomer (c2) having one vinyl group as constitutional units. Examples of the monomer (c1) having two or more vinyl groups are divinyl monomers (divinylbenzene, divinyltoluene, etc.) and polyfunctional (meth) acrylic acid esters {(polyoxy) ethylene glycol di (meth) acrylate, neopentyl glycol di (meth ) Acrylate, 1,6-hexanediol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, etc.)}. Of these, divinyl monomers and di (meth) acrylic acid esters among polyfunctional (meth) acrylic acid esters and combinations thereof are preferable.

As the monomer (c2) having one vinyl group, styrenes [styrene, alkylstyrene (α-
Methylstyrene, o-, m- or p-methylstyrene, p-ethylstyrene, 2,4-dimethylstyrene,
p-n-butylstyrene, p-tert-butylstyrene, p-n-hexylstyrene, p-n-octylstyrene, etc.)], vinyl esters (vinyl acetate, vinyl propionate, etc.), aliphatic hydrocarbon vinyl (Butadiene, etc.), nitriles (acrylonitrile, methacrylonitrile, etc.), vinyl ethers (vinyl methyl ether, vinyl ethyl ether, etc.), vinyl ketones (vinyl methyl ketone, vinyl hexyl ketone, etc.), N-vinyls (N- Vinylpyrrole, N-vinylcarbazole,
N-vinyl indole, N-vinyl pyrrolidone, etc.), vinyl halides (vinyl chloride, etc.), (meth) acrylic acid and (meth) acrylic acid ester {alkyl (meth) acrylate [methyl (meth) acrylate, butyl (meth ) Acrylate, trifluoroethyl (meth)
Acrylate and the like], heterocyclic (meth) acrylate [tetrahydrofurfuryl (meth) acrylate and the like], hydroxyalkyl (meth) acrylate [hydroxyethyl (meth) acrylate, hydroxypropyl (meth)]
Acrylate, etc.], hydroxypolyoxyalkylene (oxyalkylene group preferably has 2 to 4 carbon atoms)
(Meth) acrylate [hydroxypolyoxyethylene (meth) acrylate, hydroxypolyoxypropylene (meth) acrylate, etc.], alkoxy (alkoxy group preferably has 1 to 4 carbon atoms) alkyl (alkyl group preferably has 2 carbon atoms) To 3) (meth) acrylate [methoxyethyl (meth) acrylate, ethoxyethyl (meth) acrylate, etc.], amino group-containing (meth) acrylate [dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, etc.] Can be mentioned. Of these, preferred are styrenes, nitriles, (meth) acrylic acid esters and combinations thereof.

The amount of (c1) contained as a structural unit in the crosslinked vinyl polymer (C) is usually 0.01 to 1.
It is 0% by weight, preferably 0.05 to 5% by weight. Outside this range, a good gel electrolyte cannot be obtained.

Examples of the polymerization initiator used in the synthesis of the crosslinked vinyl polymer (C) include a thermal polymerization initiator and an actinic ray polymerization initiator. As the thermal polymerization initiator, peroxides {(cumene hydroperoxide, benzoyl peroxide, 2,2-bis (4,4-di-t-butylperoxycyclohexyl) propane, 1,1-bis (t-butyl) Peroxy) -3,3,5-trimethylcyclohexane and the like} and azo compounds (azobisisobutyronitrile and the like), etc. The type and amount of the initiator are not particularly limited and may be determined as necessary.

As the actinic ray polymerization initiator, carbonyl compounds [benzoins [benzoin, bezoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, α-methylbenzoin, α-phenylbenzoin, etc.], anthraquinones [Anthraquinone, methyl anthraquinone,
Chloranthraquinone, etc.], sulfur compounds {diphenyl sulfide, dithiocarbamates etc.}, polycondensed ring hydrocarbon halides {α-chloromethylnaphthalene etc.}, pigments {acrylflavin, fluorescein etc.},
Metal salts {iron chloride, silver chloride, etc.}, onium salts {p-methoxybenzenediazonium, hexafluorophosphate, diphenyliodonium, triphenylsulfonium, etc.}, benzyl, diacetyl, acetophenone, benzophenone and methylbenzoylformate, etc. Is mentioned. These can be used alone or as a mixture of two or more kinds.

Among the polymerization initiators, the thermal polymerization initiator is preferable.

The method for polymerizing the crosslinked vinyl polymer (C) of the present invention is not particularly limited, but the suspension polymerization method is preferred.

The gel electrolyte of the present invention comprises a non-aqueous solvent (A),
It is obtained by mixing the electrolyte salt (B) and the crosslinked vinyl polymer (C). The mixing method is not particularly limited, but a method of mixing (C) with an electrolytic solution in which (A) and (B) are previously dissolved is preferable. You may heat as needed.

When the gel electrolyte of the present invention is used as an electrolyte for driving an aluminum electrolytic capacitor, a non-aqueous solvent is preferably a lactone solvent and an electrolyte salt is preferably an ammonium salt.

When the gel electrolyte of the present invention is used in a lithium battery electrolyte, a lithium salt is preferable as the electrolyte salt.

[0018]

The present invention will be further described with reference to the following examples, but the present invention is not limited thereto. Hereinafter, parts are parts by weight.

Production Example 1 900 parts of water was charged into a reactor equipped with a thermometer, a stirrer, a gas introduction tube and a cooling tube, and styrene 720 was stirred.
Parts, 280 parts n-butyl acrylate and 0.5 parts divinyltoluene are added. Next, 4 parts of 1,1-bis (t-butylperoxy) -3,3,5-trimethylcyclohexane was added, and finally the saponification degree was 89 mol%.
100 parts of a 2.0% aqueous solution of polyvinyl alcohol was added and stirred to sufficiently disperse. After sufficiently replacing the inside of the reactor with nitrogen, polymerization was carried out at 80 ° C. for 10 hours and then at 90 ° C. for 2 hours. The polymerized slurry was washed with water and dried to obtain a polymer 1. The polymerization rate was 99.5%.

Production Example 2 450 parts of water was added to a reactor equipped with a thermometer, a stirrer, a gas introduction tube and a cooling tube, and 250 parts of styrene was added while stirring.
83 parts of n-butyl acrylate, divinylbenzene 0.
Add 7 parts of the mixture. Next, 1 part of benzoyl peroxide was added, and finally, 50 parts of a 2.0% aqueous solution of polyvinyl alcohol having a saponification degree of 89 mol% was added and stirred,
Dispersed well. After thoroughly purging the inside of the reactor with nitrogen,
Polymerization was performed at 20 ° C. for 20 hours and further at 95 ° C. for 2 hours. The polymerized slurry was washed with water and dried to obtain a polymer 2. Polymerization rate is 99%
Met.

Production Example 3 900 parts of water was put into a reactor equipped with a thermometer, a stirrer, a gas introduction tube and a cooling tube, and styrene 720 was stirred.
Part, 280 parts of n-butyl acrylate, and 1 part of ethylene glycol diacrylate were added. Next 1,
4 parts of 1-bis (t-butylperoxy) -3,3,5-trimethylcyclohexane was added, and finally the saponification degree was 8
2.0% aqueous solution of 9 mol% polyvinyl alcohol 10
0 part was added and stirred to sufficiently disperse. After sufficiently replacing the inside of the reactor with nitrogen, 80 ° C x 10 hours, and further 90 ° C x 2
Polymerized for hours. The polymerized slurry was washed with water and dried to obtain Polymer 3. The polymerization rate was 99.5%.

Production Example 4 Polymer 4 was obtained in the same manner as in Production Example 1 except that divinyltoluene was not used. The polymerization rate was 99%.

The ionic conductivity and high temperature fluidity were evaluated by the following methods. Ion conductivity: AC impedance method (25 ° C). High temperature fluidity: Measure fluidity at 100 ° C.

Example 1 20 parts of Polymer 1 was added to an electrolytic solution prepared by dissolving 10 parts of LiBF ₄ in 100 parts of propylene carbonate and mixed at room temperature to obtain a gel electrolyte. Ionic conductivity and hot fluidity were measured. The results are shown in Table 1.

Example 2 15 parts of Polymer 2 was added to an electrolytic solution prepared by dissolving 5 parts of diammonium azelate in 100 parts of γ-butyrolactone,
A gel electrolyte was obtained by mixing at room temperature. Ionic conductivity and hot fluidity were measured. The results are shown in Table 1.

Example 3 15 parts of Polymer 3 was added to an electrolytic solution prepared by dissolving 10 parts of LiClO ₄ in 100 parts of dimethoxyethane and mixed at room temperature to obtain a gel electrolyte. Ionic conductivity and hot fluidity were measured. The results are shown in Table 1.

[0027]

[Table 1] Ionic conductivity High temperature fluidity (S / cm) --------------------------------- Gel electrolyte 2 × 10 ⁻³ No fluidity Gel electrolyte of Example 2 2.5 × 10 ⁻³ No fluidity Gel electrolyte of Example 3 3.4 × 10 ⁻³ No fluidity

Comparative Example 1 20 parts of Polymer 4 was added to an electrolytic solution prepared by dissolving 10 parts of LiBF ₄ in 100 parts of propylene carbonate and mixed at room temperature, but it was a fluid liquid and did not form a gel.

[0029]

EFFECTS OF THE INVENTION The gel electrolyte of the present invention has a high ionic conductivity, and has good electrochemical characteristics and shape retention at high temperatures, so that it exhibits its effects when used in electrochromic devices, capacitors, batteries and the like.

Claims (4)

[Claims] 1. A gel electrolyte comprising a mixture of a non-aqueous solvent (A), an electrolyte salt (B) and a crosslinked vinyl polymer (C). 2. The gel electrolyte according to claim 1, wherein the crosslinked vinyl polymer (C) contains 0.01 to 10% by weight of a monomer (c1) having two or more vinyl groups as a constituent unit. .. 3. The gel electrolyte according to claim 1, wherein the gel electrolyte is an electrolyte for driving an aluminum electrolytic capacitor. 4. The gel electrolyte according to claim 1, wherein the gel electrolyte is a lithium battery electrolyte.