JP2003303619A - Ion conduction gel electrolyte and lithium secondary battery using the electrolyte - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ion conduction gel electrolyte and a lithium secondary battery using that electrolyte. <P>SOLUTION: This is an ion conduction gel electrolyte in which, after a polymer is wetted or swollen with a supercritical fluid, the polymer having many pores obtained by removing the supercritical fluid is wetted and swollen with an electrolytic solution. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a porous ion conductive electrolyte using a supercritical fluid, and a lithium secondary battery using the electrolyte.

[0002]

2. Description of the Related Art Recently, as a high density and high capacity secondary battery,
The development of lithium secondary batteries, such as lithium-ion batteries and lithium batteries that also use metallic lithium as an electrode, is in the spotlight.

Lithium is the most useful metal for obtaining a high-density and high-capacity battery because it has the most basic redox potential. However, since an organic solvent is used for the electrolytic solution,
Various problems have arisen.

For example, as compared with the case where water is used as the electrolytic solution, the organic solvent has a high viscosity, and as a result, the diffusion of ions is slowed, the ionic conductivity tends to be low, and the charge / discharge characteristics tend to be poor. .

Further, when an internal short circuit or an external short circuit occurs in the lithium secondary battery, if an organic solvent is used as the electrolytic solution, the electrolytic solution may volatilize, leak, or explode.

Therefore, a large number of ion conductive gel electrolytes have been developed as electrolytes for lithium secondary batteries having high ionic conductivity and no leakage of organic solvent.

Although these gel electrolytes have achieved some results, they have not reached the level applicable to ion-conductive lithium secondary batteries which require high ionic conductivity. For example, a gel electrolyte is usually obtained by adding a monomer having an unsaturated double bond or a cross-linking reactive polymer to the electrolyte in which the electrolytic salt is dissolved, and further polymerizing the polymer. Inhibits the movement of ions, so that the ionic conductivity becomes lower than that of the organic solvent type electrolyte.

A gel electrolyte using a porous polymer has also been developed in order to reduce the influence of the polymer in the gel electrolyte on the movement of ions (Japanese Patent Laid-Open No. 200-200200).
1-1143756, JP 2001-172421A, JP 9-259923A, etc.), the manufacturing process is complicated, and a plasticizer may be used, which has a large impact on the environment.

[0009]

The invention according to claim 1 provides an ionic conductive gel electrolyte having high ionic conductivity.

In addition to the invention of claim 1, the invention of claim 2 provides an ion conductive gel electrolyte having a low environmental load.

The invention according to claim 3 provides a lithium secondary battery having high ion conductivity.

[0012]

The present invention relates to the following: (1) After wetting or swelling a polymer with a supercritical fluid,
Ion conductive gel electrolyte characterized by wetting or swelling a polymer having many pores obtained by excluding the supercritical fluid with an electrolytic solution (2) characterized in that the supercritical fluid is carbon dioxide Ion conductive gel electrolyte according to (1) above (3) Lithium secondary battery using the ion conductive electrolyte according to (1) or (2) above

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION In the porous ion conductive gel electrolyte of the present invention, a method may be mentioned in which a polymer is previously wetted or swollen in a supercritical fluid and then the supercritical fluid is removed.

In the present invention, the supercritical fluid includes
It is preferable to use carbon dioxide. In the present invention,
As a polymer for wetting and swelling with a supercritical fluid,
Although not limited to the following, for example, a physically crosslinkable polymer such as polyvinylidene fluoride and polyacrylonitrile, and a chemically crosslinkable thermosetting polymer having a three-dimensional network structure in a polymer such as a vinyl monomer. Examples include molecules.

In the present invention, the monomer for obtaining the thermosetting polymer is not limited to the following, but for example, methyl methacrylate, benzyl methacrylate, methyl acrylate, ethyl acrylate, N-propyl acrylate, i-propyl acrylate, n-acrylic acid
-Butyl, i-butyl acrylate, t-butyl acrylate, pentyl acrylate, n-hexyl acrylate, 2-ethylhexyl acrylate, n-octyl acrylate, dodecyl acrylate, octadecyl acrylate, butoxyethyl acrylate, Acrylic esters such as phenyl acrylate, benzyl acrylate, naphthyl acrylate, glycidyl acrylate, 2-hydroxyethyl acrylate, ethyl methacrylate, n-propyl methacrylate, i-propyl methacrylate, n-methacrylate.
Butyl, i-butyl methacrylate, t-butyl methacrylate, pentyl methacrylate, n-hexyl methacrylate, 2-ethylhexyl methacrylate, n methacrylate
(Meth) such as octyl, dodecyl methacrylate, octadecyl methacrylate, butoxyethyl methacrylate, phenyl methacrylate, naphthyl methacrylate, glycidyl methacrylate, 2-hydroxyethyl methacrylate.
Acrylic esters, cyclopentyl acrylate, cyclohexyl acrylate, methyl cyclohexyl acrylate, trimethyl cyclohexyl acrylate, norbornyl acrylate, norbornyl methyl acrylate, phenyl norbornyl acrylate, cyano norbornyl acrylate, acrylic acid Isobornyl, bornyl acrylate, menthyl acrylate, fentyl acrylate, adamantyl acrylate, dimethyl adamantyl acrylate, tricyclo [5.2.1.0 ^2,6 ] deca-8-yl, tricyclo acrylate [5. 2.1.0
^2,6 ] Deca-4-methyl, cyclodecyl acrylate, cyclopentyl methacrylate, cyclohexyl methacrylate, methylcyclohexyl methacrylate, trimethylcyclohexyl methacrylate, norbornyl methacrylate, norbornyl methyl methacrylate, cyanonorbornyl methacrylate, Phenyl norbornyl methacrylate, isobornyl methacrylate, bornyl methacrylate, menthyl methacrylate, fentyl methacrylate,
Adamantyl methacrylate, dimethyladamantyl methacrylate, tricyclomethacrylate [5.2.1.0]
^2,6 ] deca-8-yl, tricyclomethacrylate [5.
2.1.0 ^2,6 ] Deca-4-methyl, alicyclic (meth) acrylic acid such as cyclodecyl methacrylate, 4-vinylpyridine, 2-vinylpyridine, α-methylstyrene,
α-ethylstyrene, α-fluorostyrene, α-chlorostyrene, α-bromostyrene, fluorostyrene,
Aromatic vinyl compounds such as chlorostyrene, bromostyrene, methylstyrene, methoxystyrene, styrene, acrylamide, methacrylamide, N-dimethylacrylamide, N-diethylacrylamide, N-dimethylmethacrylamide, N-diethylmethacrylamide, etc. ) Acrylamides, calcium acrylate, barium acrylate, lead acrylate, tin acrylate acrylate, zinc acrylate, calcium methacrylate, barium methacrylate, lead methacrylate, tin methacrylate, zinc methacrylate, etc. (meth) Acrylic acid metal salt,
Unsaturated fatty acids such as acrylic acid and methacrylic acid, vinyl cyanide compounds such as acrylonitrile and methacrylonitrile, N-methylmaleimide, N-ethylmaleimide, N
-Propylmaleimide, N-i-propylmaleimide,
N-butyl maleimide, N-i-butyl maleimide, N
-T-butylmaleimide, N-laurylmaleimide, N
-Cyclohexylmaleimide, N-benzylmaleimide, N-phenylmaleimide, N- (2-chlorophenyl) maleimide, N- (4-chlorophenyl) maleimide, N- (4-bromophenyl) phenylmaleimide,
N- (2-methylphenyl) maleimide, N- (2-ethylphenylmaleimide, N- (2-methoxyphenyl) maleimide, N- (2,4,6-trimethylphenyl) maleimide, N- (4-benzylphenyl) ) Maleimides, maleimides such as N- (2,4,6-tribromophenyl) maleimide, nonamethylene glycol diacrylate, tridecamethylene glycol diacrylate, tetradecamethylene glycol diacrylate, tricosamethylene glycol diacrylate, etc. Polymethylene glycols such as polymethylene glycol diacrylate, nonamethylene glycol dimethacrylate, tridecamethylene glycol dimethacrylate, tetradecamethylene glycol dimethacrylate, tricosamethylene glycol dimethacrylate Polyethylene glycol diacrylate such as call dimethacrylate, nonaethylene glycol diacrylate, tridecaethylene glycol diacrylate, tetradecaethylene glycol diacrylate, tricosaethylene glycol diacrylate, nonaethylene glycol dimethacrylate, tridecaethylene glycol dimethacrylate, Polyethylene glycol dimethacrylate such as tetradeca ethylene glycol dimethacrylate, tricosa ethylene glycol dimethacrylate, nonapropylene glycol diacrylate, dodecapropylene glycol diacrylate, polypropylene glycol diacrylate such as tridecapropylene glycol diacrylate, nonapropylene glycol dimethacrylate , Dodecap Pyrene glycol dimethacrylate, polypropylene glycol dimethacrylate such as tridecapropylene glycol dimethacrylate, nonabutylene glycol diacrylate, dodecabutylene glycol diacrylate, polybutylene glycol diacrylate such as tridecabutylene glycol diacrylate, nonabutylene glycol dimethacrylate, Polybutylene glycol dimethacrylate such as dodecabutylene glycol dimethacrylate, tridecabutylene glycol dimethacrylate, heptaethylene glycol tripropylene glycol diacrylate, nonaethylene glycol propylene glycol diacrylate, tetradecaethylene glycol propylene glycol diacrylate, nonaethylene glycol Dipro Polyethylene glycol polypropylene glycol diacrylate such as pyrene glycol diacrylate, tetradeca ethylene glycol dipropylene glycol diacrylate, nona ethylene glycol tripropylene glycol diacrylate, tetradeca ethylene glycol tripropylene glycol diacrylate,
Heptaethylene glycol tripropylene glycol dimethacrylate, nonaethylene glycol propylene glycol dimethacrylate, tetradecaethylene glycol propylene glycol dimethacrylate, nonaethylene glycol dipropylene glycol dimethacrylate, tetradecaethylene glycol dipropylene glycol dimethacrylate, nonaethylene glycol trimethacrylate Polyethylene glycol polypropylene glycol dimethacrylate such as propylene glycol dimethacrylate and tetradecaethylene glycol tripropylene glycol dimethacrylate, polyethylene glycol polybutylene glycol diacrylate such as decaethylene glycol pentabutylene glycol diacrylate, decaethylene glycol Polyethylene glycol polybutylene glycol dimethacrylate such as penta-butylene glycol dimethacrylate, 2,2-dimethyl-1,3
Propanediol diacrylate, 2-methyl-2-ethyl-1,3-propanediol diacrylate, 2-
Methyl-2-isopropyl-1,3-propanediol diacrylate, 2-methyl-2-propyl-1,3-
Propanediol diacrylate, 2,2-diethyl-
1,3-propanediol diacrylate, 2-ethyl-2-propyl-1,3-propanediol diacrylate, 2-ethyl-2-isopropyl-1,3-propanediol diacrylate, 2-ethyl-2-butyl −
1,3-propanediol diacrylate, 2,2-dipropyl-1,3-propanediol diacrylate,
2-Propyl-2-butyl-1,3-propanediol diacrylate, 2,2-dibutyl-1,3-propanediol diacrylate, 2,2-diisopropyl-
1,3-propanediol diacrylate, 2-propyl-2-isopropyl-1,3-propanediol diacrylate, 2-methyl-2-phenyl-1,3-propanediol diacrylate, 2-ethyl-2-phenyl -1,3-propanediol diacrylate, 2-propyl-2-phenyl-1,3-propanediol diacrylate, 2-isopropyl-2-phenyl-1,3
-Propanediol diacrylate, 2,2-diphenyl-1,3-propanediol diacrylate, 2-methyl-2-cyclopentyl-1,3-propanediol diacrylate, 2-ethyl-2-cyclopentyl-
1,3-propanediol diacrylate, 2-propyl-2-cyclopentyl-1,3-propanediol diacrylate, 2-isopropyl-2-cyclopentyl-1,3-propanediol diacrylate, 2,2-
Dicyclopentyl-1,3-propanediol diacrylate, 2-methyl-2-cyclohexyl-1,3-propanediol diacrylate, 2-ethyl-2-cyclohexyl-1,3-propanediol diacrylate, 2-propyl- 2-cyclohexyl-1,3-propanediol diacrylate, 2-isopropyl-2-
Polyfunctional acrylates such as cyclohexyl-1,3-propanediol diacrylate and 2,2-dicyclohexyl-1,3-propanediol diacrylate, 2,
2-dimethyl-1,3-propanediol dimethacrylate, 2-methyl-2-ethyl-1,3-propanediol dimethacrylate, 2-methyl-2-isopropyl-1,3-propanediol dimethacrylate, 2-methyl 2-propyl-1,3-propanediol dimethacrylate, 2,2-diethyl-1,3-propanediol dimethacrylate, 2-ethyl-2-propyl-
1,3-propanediol dimethacrylate, 2-ethyl-2-isopropyl-1,3-propanediol dimethacrylate, 2-ethyl-2-butyl-1,3-propanediol dimethacrylate, 2,2-dipropyl-
1,3-propanediol dimethacrylate, 2-propyl-2-butyl-1,3-propanediol dimethacrylate, 2,2-dibutyl-1,3-propanediol dimethacrylate, 2,2-diisopropyl-1,3
-Propanediol dimethacrylate, 2-propyl-
2-isopropyl-1,3-propanediol dimethacrylate, 2-methyl-2-phenyl-1,3-propanediol dimethacrylate, 2-ethyl-2-phenyl-1,3-propanediol dimethacrylate, 2-
Propyl-2-phenyl-1,3-propanediol dimethacrylate, 2-isopropyl-2-phenyl-
1,3-propanediol dimethacrylate, 2,2-
Diphenyl-1,3-propanediol dimethacrylate, 2-methyl-2-cyclopentyl-1,3-propanediol dimethacrylate, 2-ethyl-2-cyclopentyl-1,3-propanediol dimethacrylate, 2-propyl-2 -Cyclopentyl-1,3-propanediol dimethacrylate, 2-isopropyl-
2-cyclopentyl-1,3-propanediol dimethacrylate, 2,2-dicyclopentyl-1,3-propanediol dimethacrylate, 2-methyl-2-cyclohexyl-1,3-propanediol dimethacrylate, 2-ethyl- 2-cyclohexyl-1,3-propanediol dimethacrylate, 2-propyl-2-cyclohexyl-1,3-propanediol dimethacrylate, 2-isopropyl-2-cyclohexyl-1,3-
Polyfunctional methacrylates such as propanediol dimethacrylate and 2,2-dicyclohexyl-1,3-propanediol dimethacrylate, ethylene glycol diacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, tetraethylene glycol diacrylate, glycerin diacrylate , 1,3-butylene glycol diacrylate, 1,
4-butanediol diacrylate, 1,6-hexanediol diacrylate, 1,9-nonanediol diacrylate, 1,10-decanediol diacrylate, 1,12-dodecanediol diacrylate, propylene glycol diacrylate, dipropylene Glycol diacrylate, tripropylene glycol diacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, 1,1,1-
Trimethylolpropane triacrylate, dipentaerythritol hexaacrylate, hexamethylolmelamine hexaacrylate, N, N ', N "-tris (2
-Acryloyloxyethyl) isocyanurate, 2,2 '
-Bis [4- (acryloxyethoxy) phenyl] propane, 2,2'-bis [4- (acryloxyethoxy)
Phenyl] methane, 2,2'-bis [4- (acryloxy.
Diethoxy) phenyl] propane, 2,2'-bis [4-
(Acryloxy-diethoxy) phenyl] methane, 2,2 '
-Bis [4- (acryloxypentaethoxy) phenyl] propane, 2,2'-bis [4- (acryloxypentaethoxy) phenyl] methane, 2,2'-bis [4- (acryloxypentadecaethoxy) Phenyl] propane, 2,2'-bis [4- (acryloxy pentadecaethoxy) phenyl] methane, 2,2'-bis [4- (acryloxy propyleneoxy) phenyl] propane, 2,2'-
Bis [4- (acryloxy-propyleneoxy) phenyl] methane, 2,2'-bis [4- (acryloxy-dipropyleneoxy) phenyl] propane, 2,2'-bis [4-
(Acryloxy-dipropyleneoxy) phenyl] methane, 2,2'-bis [4- (acryloxypentapropyleneoxy) phenyl] propane, 2,2'-bis [4- (acryloxypentapropyleneoxy) phenyl] methane , 2,2'-bis [4- (acryloxy pentadecapropyleneoxy) phenyl] propane, 2,2'-bis [4-
(Acryloxy pentadecapropyleneoxy) phenyl] methane, bis (acryloxymethyl) tricyclo [5.2.1.02,6] decane, bis (acryloxymethyl) pentacyclo [6.5.13,6.02, 7.09,13] Pentadecane, bis (acryloxymethyl) heptacyclo [10.5.1.13,10.15,8.02,11.04,9.013,17]
Polyfunctional acrylates such as eicosane, tetramethylolmethane triacrylate, tetramethylolmethane tetraacrylate, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, glycerin dimethacrylate, 1,3-butylene Glycol dimethacrylate,
1,4-butanediol dimethacrylate, 1,6-hexanediol dimethacrylate, 1,9-nonanediol dimethacrylate, 1,10-decanediol dimethacrylate, 1,12-dodecanediol dimethacrylate, propylene glycol dimethacrylate, Dipropylene glycol dimethacrylate, tripropylene glycol dimethacrylate, pentaerythritol trimethacrylate, pentaerythritol tetramethacrylate, 1,1,1-trimethylolpropane trimethacrylate, dipentaerythritol hexamethacrylate, hexamethylolmelamine hexamethacrylate, N, N ' , N "-tris (2-methacryloyloxyethyl cyanurate, 2,2'-bis [4- (methacryloxyethoxy) phene] Le] propane, 2,2'-bis [4-
(Methacryloxy-ethoxy) phenyl] methane, 2,2 '
-Bis [4- (methacryloxydiethoxy) phenyl] propane, 2,2'-bis [4- (methacryloxydiethoxy) phenyl] methane, 2,2'-bis [4- (methacryloxypentaethoxy) phenyl] propane , 2,
2'-bis [4- (methacryloxypentaethoxy) phenyl] methane, 2,2'-bis [4- (methacryloxy.
Pentadecaethoxy) phenyl] propane, 2,2'-bis [4- (methacryloxypentadecaethoxy) phenyl] methane, 2,2'-bis [4- (methacryloxypropylenepropylene) phenyl] propane, 2,2 '-Bis [4-
(Methacryloxy-propyleneoxy) phenyl] methane, 2,2'-bis [4- (methacryloxy-dipropyleneoxy) phenyl] propane, 2,2'-bis [4- (methacryloxy-dipropyleneoxy) phenyl] methane,
2,2'-bis [4- (methacryloxypentapropyleneoxy) phenyl] propane, 2,2'-bis [4- (methacryloxypentapropyleneoxy) phenyl] methane, 2,2'-bis [4- ( Methacryloxy pentadecapropyleneoxy) phenyl] propane, 2,2'-bis [4
-(Methacryloxy-pentadecapropyleneoxy)
Phenyl] methane, bis (methacryloxymethyl) tricyclo [5.2.1.02,6] decane, bis (methacryloxymethyl) pentacyclo [6.5.13,6.02,7.0
9,13] Pentadecane, bis (methacryloxymethyl) heptacyclo [10.5.1.13,10.15,8.02,11.04,
9.013,17] Eicosane, Tetramethylolmethane trimethacrylate, Tetramethylolmethane tetramethacrylate and other polyfunctional methacrylates, ethylene glycol bisallyl carbonate, diethylene glycol bisallyl carbonate, triethylene glycol bisallyl carbonate, tetraethylene glycol bisallyl carbonate , Pentaethylene glycol bisallyl carbonate, polypropylene glycol bisallyl carbonate, trimethylene glycol bisallyl carbonate, 3-hydroxypropoxy propanol bisallyl carbonate, glycerin bisallyl carbonate, triglycerine bisallyl carbonate, diallyl carbonate, diarylidene pentaerythritol, Triallylidene sorbito Le, Gialidene-2,2
6,6-Tetramethylol cyclohexanone, triallylidene hexamethylol melamine, diarylidene-D-
Glucose, bisphenol A diallyl ether, bisphenol S diallyl ether, ethylene glycol diallyl ether, diethylene glycol diallyl ether, triethylene glycol diallyl ether, 1,
1,1-trimethylolpropane triallyl ether,
Neopentyl glycol triallyl ether, allyl acrylate, methallyl acrylate, vinyl acrylate, diallyl phthalate (diallyl orthophthalate,
Diallyl isophthalate, diallyl terephthalate and a mixture of two or more thereof), allyl methacrylate, methallyl methacrylate, vinyl methacrylate, diallyl phthalate (diallyl orthophthalate, diallyl isophthalate, diallyl terephthalate and a mixture of two or more thereof), triallyl isocyanate Examples thereof include allyl compounds such as nurate and allylidene compounds, and divinylbenzene. You may use these monomers by 1 type (s) or 2 or more types.

In the present invention, the polymer to be moistened or swollen with the supercritical fluid may have unreacted functional groups left, and when the polymer is moistened or swollen with the supercritical fluid, a polymerization catalyst is added in advance. Alternatively, the unreacted functional group may be reacted.

In the present invention, the polymer to be moistened or swollen with the supercritical fluid may still have unreacted functional groups, and after the moistening or swelling with the electrolytic solution, a polymerization catalyst is added in advance to obtain the unreacted functional group. The functional group of the reaction may be reacted.

In the present invention, the electrolytic salt is not limited to the following. For example, LiCl, LiF, LiC
lO ₄ , LiBF ₄ , LiPF ₆ , LiAsF ₆ , Li
CF ₃ SO ₃ , LiC ₄ F ₉ SO ₃ and LiN (CF ₃
SO ₂ ) _{2 and the} like. These may be used alone or in combination of two or more.

The addition amount of the electrolytic salt in the present invention is preferably 0.01 to 50% by weight, and more preferably 0.1 to 30% by weight, based on the above organic solvent. If the addition amount is less than 0.01% by weight, the ionic conductivity tends to be low, and if it exceeds 50% by weight, a salt tends to be precipitated.

The organic solvent used in the electrolytic solution in the present invention is not limited to the following, but for example, acetonitrile, N, N-dimethylformamide, dimethylsulfoxide, hexamethylphosphoramide, N-
Examples include aprotic organic solvents such as methylpyrrolidone, dimethyl carbonate, ethylene carbonate, diethyl carbonate, propylene carbonate, butylene carbonate and methyl ethyl carbonate. You may use these organic solvents by 1 type (s) or 2 or more types.

[0021] For the polymer deprived of the supercritical fluid after wetting or swelling in the supercritical fluid in the present invention,
The amount of the electrolyte obtained by dissolving the electrolytic salt in the organic solvent is 1
It is preferably from 0 to 95% by weight. This addition amount is 1
If it is less than 0% by weight, the ionic conductivity tends to be low, and if it is more than 95% by weight, the electrolytic solution tends to leak from the gel electrolyte.

In the gel electrolyte in the present invention, if necessary, fine particle fillers such as alumina, silica, magnesium oxide, talc, barium titanate and barium sulfate, dyes such as Victoria Pure Blue, pigments such as phthalocyanine green, etc. The colorant and the like may be included.

In the gel electrolyte of the present invention, if necessary, a plasticizer such as dibutyl phthalate, a flame retardant such as phosphoric acid ester, an adhesion promoter such as benzotriazole,
A silicon-based leveling agent, a phenol-based antioxidant, a thioether-based antioxidant, or the like may be added and used.

The thickness of the gel electrolyte in the present invention varies depending on the use, but it is preferably 1 to 1000 μm, more preferably 2 to 500 μm. If this thickness is less than 1 μm, it tends to be difficult to apply industrially, and if it exceeds 1000 μm, the charge / discharge characteristics tend to be insufficient.

The ionic conductivity of the gel electrolyte in the present invention is preferably 10 ⁻⁹ S / cm or more, and 10
It is particularly preferably ^-8 S / cm or more.

The gel electrolyte of the present invention can also be used in electrochemical devices other than lithium secondary batteries.
The electrochemical device is not particularly limited as long as it accumulates, increases, decreases, or releases energy by an electrochemical change, and it can be used in batteries such as nickel-hydrogen batteries, fuel cells, and electrochemical sensors. Examples include chemical devices.

Further, since the electrolyte of the present invention exhibits a change in color tone due to a potential difference, it can be applied to a light control device for indoor temperature control, a device to which these are applied, and the like.

A battery using the gel electrolyte of the present invention is constructed by joining a positive electrode and a negative electrode through the electrolyte. When the battery is a lithium battery, the electrolyte contains a lithium salt. At this time, a material capable of inserting and extracting lithium is used as the positive electrode and the negative electrode of the battery. The positive electrode is not particularly limited as long as it is a material having a high potential with respect to the negative electrode, and the electron-conducting polymer compound portion serves as the positive electrode active material, and therefore may be used alone. Materials may be used together.

Examples of the positive electrode material include Li
_1-x CoO ₂ , Li _1-x NiO ₂ , Li _1-x Mn
₂ O ₄ , Li _1-x MO ₂ (0 <x <1, M is Co, N
i, Mn, Fe, etc.), Li _2-y Mn ₂ O
₄ (0 <y <2), Li _1-x V ₂ O ₅ (0 <x <
_{1), Li 2-y V} 2 O 5 (0 <y <2) Li 1-x '
Oxides such as Nb ₂ O ₅ (0 <x ′ <1.2), Li
_1-x TiS ₂ , Li _1-x MoS ₂ , Li _1-z Nb
Examples thereof include metal chalcogenites such as Se ₃ (0 <z <3), organic compounds such as dithiol derivatives and disulfide derivatives.

As the negative electrode material, a material having a lower potential than that of the positive electrode can be used. For example, metallic lithium, metallic lithium such as aluminum-lithium alloy, magnesium-aluminum-lithium alloy, AlSb, Mg.
₂ Ge, intermetallic compounds such as NiSi ₂ , graphite,
Coke, carbon-based material such as low temperature firing polymer, SnM'-based oxide (M 'represents Si, Ge, Pb, etc.), Si
_1-y M " _y O _z (M" represents W, Sn, Pb, B, etc.), lithium solid solution of metal oxides such as titanium oxide and iron oxide, Li ₇ MnN ₄ , Li ₃ FeN
₄ , Li _3-x CoxN, Li _3-x NiN, Li
_3-x Co _x N, Li _3-x Cu _x N, Li ₃ BN ₂ ,
Examples thereof include ceramics such as nitrides such as Li ₃ AlN ₂ and Li ₃ SiN ₃ .

When lithium ions are reduced at the negative electrode to be used as metallic lithium, any material having electronic conductivity may be used, and the material is not limited to the above.

The electrode is preferably formed by processing the above material into a predetermined shape. Examples of the shape of the electrode include a continuous body and a binder dispersion of a powder material. Examples of the molding method of the above continuous body include, for example, electrolysis,
Examples of forming processing methods include vapor deposition, sputtering, CVD, melting processing, sintering, and compression.

Examples of the method for molding the binder dispersion of the powder material include a molding method in which a powdery electrode material is mixed with a binder and molded. Examples of these binder materials include ion conductive polymers such as polyvinylidene fluoride, non-ion conductive polymers such as styrene / butadiene latex and polyfluoroethylene fiber latex, KF1 manufactured by Kureha Chemical Industry Co., Ltd.
000 or the like is used.

The shape of the battery has a structure in which a positive electrode material and a negative electrode material are joined together through the electrolyte, and, for example, in the unit of positive electrode material / electrolyte / negative electrode material in which film-like constituent elements are sequentially laminated, The battery may have a sheet-shaped structure, a roll-shaped structure, or the like, and the battery may have any shape such as a coil type, a sheet type or a film type, a cylindrical type, and a square type. To manufacture a flexible thin battery by sandwiching and sealing a laminate composed of a positive electrode material / electrolyte membrane / negative electrode material with an aluminum laminate material composed of polypropylene / modified polypropylene / aluminum as an outer package. You can It is also possible to make an assembled battery in which the electrodes of the battery units are connected in parallel or in series. In particular, it has a feature that the voltage can be increased depending on the number of series connections.

[0035]

The present invention will be described in more detail below with reference to examples of the present invention and comparative examples thereof, but the present invention is not limited to these examples. The evaluation method of the electrolyte obtained in this example is shown below.

<Ionic Conductivity> The ionic conductivity is measured by
An electrochemical cell is formed by sandwiching an electrolyte between stainless steel electrodes at 25 ° C., and an alternating current impedance method is used in which an alternating current is applied between the electrodes to measure a resistance component.
It was calculated from the real impedance intercept of the Cole-Cole plot.

<Synthesis Method of Polymer (P1) for Swelling in Supercritical Fluid> A monomer solution (methyl methacrylate (6 g) prepared in advance in the following ratio was prepared in a glass container having a volume of 2 cm × 2 cm × 0.5 cm. ), Tricyclomethacrylate [5.2.1.0 ^2,6 ] dec-8-yl (3 g), ethylene glycol dimethacrylate (1
g), n-octyl mercaptan (0.01 g) and lauroyl peroxide (0.04 g)). Then, the glass container was heated at 60 ° C. for 5 hours and subsequently at 90 ° C. for 2 hours to obtain P1.

[0038]

Example 1 The polymer P1 was placed in a pressure-resistant autoclave container, and the inside of the container was replaced with carbon dioxide. Then, the pressure in the container was set to Pascal and the temperature was set to 30 ° C., and the container was left for 3 hours. After leaving it for a while, return to normal temperature and pressure,
An electrolyte with many holes was obtained. This electrolyte is used as electrolyte solution (1
MLiBF ₄ , polyethylene carbonate / ethylene carbonate / dimethyl carbonate (= 1/1/1, v
sol (%) solution) for 1 hour and used as a gel electrolyte for ionic conductivity measurement. The results are shown in Table 1.

[0039]

[Comparative Example 1] The polymer P1 was mixed with an electrolytic solution (1M LiB
F ₄ , polyethylene carbonate / ethylene carbonate / dimethyl carbonate (= 1/1/1, vol%)
It was immersed in a solution) for 1 hour and used as a gel electrolyte for measurement of ionic conductivity. The results are shown in Table 1.

[0040]

[Table 1] Recipe list

[0041]

The electrolyte according to claim 1 is suitable as a gel electrolyte used in a lithium secondary battery which requires high ionic conductivity. The invention according to claim 2 has the effect of claim 1, and is further excellent in safety. The lithium secondary battery according to the third aspect is excellent in ionic conductivity and safety, and is suitable for a lithium battery, a lithium ion battery and the like.

Claims (3)

[Claims] 1. An ion characterized by wetting or swelling a polymer with a supercritical fluid, and then wetting or swelling the polymer with many pores obtained by removing the supercritical fluid with an electrolytic solution. Conductive gel electrolyte 2. The ionic conductive gel electrolyte according to claim 1, wherein the supercritical fluid is carbon dioxide. 3. A lithium secondary battery using the ion conductive electrolyte according to claim 1.