JPH0249357A - Solid polymer electrode film and manufacture thereof - Google Patents

Abstract

PURPOSE:To give such shape retainability and strength that strain is seldom produced even if pressure is applied to a film by dissolving a polymer acid salt and high ion-conductive composite in the same solvent, and forming a film with a casting mold by which phase separation of both material is produced. CONSTITUTION:An electrolyte material of the same metal salt as alkali metal salt of the polymer is added to a polymer having an alkali carboxylate group or an alkali sulfonate group in its side chain and polyalkyelene oxide or acryl elastomer to prepare a composite solution. The composite solution is poured in a casting mold in which an organic substance is studded on the mold surface having large surface tension to cast it, then dried under vacuum to form a film. The composite solution is also poured in a casting mold in which a metal vapor deposition film is continuously formed with required gaps kept on the mold surface having small surface tension to cast it, then dried under vacuum. The polymerization degree of the polymer having alkali carboxylate group or alkali sulfonate group in its side chain is 10<2>-10<5>.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a solid polymer electrolyte membrane and a method for manufacturing the same. More specifically, the present invention relates to a solid polymer electrolyte membrane having such membrane strength that it is unlikely to be distorted even when pressurized, and a method for manufacturing the same.

[Prior art] and [Problem to be solved by the invention]
Conventional solid polymer electrolytes include those with a low glass transition point (Tg), such as polyalkylene oxide, to which an electrolyte material (LiC (A 04, Li5CN, etc.) is added) that is compatible with the polyalkylene oxide in order to obtain high ionic conductivity. However, since these solid polymer electrolytes are based on polyalkylene oxide, they have a problem of high fluidity.

In order to improve this point, it is possible to maintain the shape through a cross-linking reaction, but it is still very soft and can serve as a strength element, so it does not contribute much to making batteries lighter and smaller. Not yet.

An object of the present invention is to provide a solid polymer electrolyte membrane that has shape retention and membrane strength to the extent that it does not easily become distorted even when pressurized, and that can contribute to the reduction in weight and size of batteries, and a method for manufacturing the same. It is in.

[Means to solve the problem]

The solid polymer electrolyte membrane that achieves the object of the present invention is formed from a polymer having an alkali metal carboxylate base or an alkali metal sulfonate group bonded to its side chain. It is made up of a plurality of composites in which an electrolyte material of the same metal salt as the alkali metal salt of the polymer is added to an acrylic elastomer, arranged in a columnar manner.

Such a solid polymer electrolyte membrane is manufactured by any of the following methods.

A mixture solution of a polymer having a carboxylic acid alkali metal base or a sulfonic acid alkali metal base bound to its side chain, and a composite of polyalkylene oxide or acrylic elastomer to which an electrolyte substance of the same metal salt as the alkali metal salt of the above polymer is added. (1) A method of casting and casting into a cast mold in which organic matter is dotted on the surface of the cast mold with a high surface tension, and drying under reduced pressure.(2) A method of applying a metal vapor-deposited film on the surface of the mold with a low surface tension. Casting is carried out in a cast mold formed continuously with the necessary gaps, and then dried under reduced pressure. For coalescence, the degree of polymerization is generally IO2 to 10S, preferably 103 to 1
0' is used.

Examples of polymers having carboxylic acid groups include polyacrylic acid and ethylene-acrylic acid copolymer.

Ethylene-methacrylic acid copolymer, propylene-acrylic acid copolymer, propylene-methacrylic acid copolymer, methyl acrylate-acrylic acid copolymer.

Methyl methacrylate-acrylic acid copolymer, ethylene-
Methyl acrylate-acrylic acid terpolymer.

Examples include ethyl acrylate-acrylic acid copolymer, and the carboxylic acid group-containing monomer is used in a proportion of 100 to 30 mol% in the polymer.

In addition, examples of the polymer having a sulfonic acid group include poly(ethylene sulfonic acid), poly(P-styrene sulfone a), styrene-P-styrene sulfonic acid copolymer,
Examples include poly(propylene sulfonic acid), methyl acrylate-propylene sulfonic acid copolymer, and the sulfonic acid group-containing monomer is used in a proportion of 100 to 30 mol% in the polymer.

The side chain carboxylic acid group or sulfonic acid group of these polymers is used by forming an alkali metal salt with an alkali metal represented by lithium or sodium.

Formation of metal salts generally occurs between about 0.1 and 2 of these polymeric acids.
This is done by mixing a 0% aqueous solution with an acid-equivalent amount of alkali metal hydroxide, etc., and neutralizing it, thereby forming a polymeric acid salt.

In addition, the polyalkylene oxide or acrylic elastomer that forms the main component of the composite has a degree of polymerization of about 10.
Polyalkylene oxide such as polyethylene oxide and polypropylene oxide having a temperature of 1 to 1038 degrees, or (a) alkyl acrylate having an alkyl group having 1 to 8 carbon atoms and/or alkoxyalkyl acrylate having an alkoxyalkyl group having 2 to 8 carbon atoms, and crosslinked Acrylic elastomer, which is a copolymer of a vinyl monomer containing a functional group (Japanese Patent Application No. 62-51600, No. 62-
78904) is used.

Electrolyte substances that are added to these polyalkylene oxides or acrylic elastomers and are compatible with them include hydrohalic acid, perhalogenated oxyacid, halogenated oxyacid, subhalogenated oxyacid, and hypohalogenated oxyacid. acids, tetrahalogenated boric acid, hexahalogenated phosphoric acid,
Alkali metal salts such as trihalogenated metasulfonic acid, thiocyanic acid, nitric acid, sulfuric acid, phosphoric acid, and carbonic acid are used, preferably perchlorates such as lithium perchlorate, and thiocyanic acids such as sodium thiocyanate and lithium thiocyanate. Salt is used. These electrolyte materials are suitable for polyalkylene oxides or acrylic elastomers.
About 0.1-100% by weight, preferably about 5-25% by weight
is used at a ratio of 1 to form a complex.

Both the polymeric acid salt and this complex are prepared in the same solvent, such as water, dimethyl sulfoxide, dimethylformamide,
Dimethylacetamide, N-methylpyrrolidone, etc.
Each of these is applied to casting as a mud mixture dissolved to a concentration of about 5 to 20%.

The polymeric acid salt and the complex have a volume ratio of approximately 50% of the polymeric acid salt.
~95%, preferably about 60-70%, with a complex of about 50%
- Nishiki, preferably in an amount of about 40 to 3 liters, and when the solution concentrations of both are the same, they are used in solution amounts of this ratio.

Such a ratio is selected from the viewpoint that the polymeric acid salt forms a continuous film-like material and imparts strength thereto.

Casting using this mixture solution is carried out using a cast mold whose surface is dotted with many areas of low surface tension. When a mixture solution is cast into such a cast mold, the polymeric acid salt will wet the areas of relatively high surface tension, and the highly ionic conductive composite will wet the scattered areas of low surface tension. Therefore, phase separation occurs in the film thickness direction, and a large number of columnar parts are formed in the film thickness direction of the film formed from the polymeric acid salt. A state where most of the columnar parts with a diameter of about 5 to 200 μI penetrate through the film thickness direction of a film-like body formed with a film thickness of several μm or more, generally about 10 to 500 μm from the viewpoint of film strength. is formed.

Cast molds with low surface tension parts used to form columnar parts are: (1) Silicone oil is applied to the surface of the cast mold made of glass, metal, ceramics, etc. with high surface tension. , can be produced by dotting an organic substance such as fluorocarbon, and the method of dotting the organic substance is to apply a dispersion in which the organic substance is emulsified and dispersed in water etc. to the cast mold surface and volatilize the dispersion medium, or Spraying methods etc. are used.

(2) Cast mold surfaces with low surface tension, such as those made of polymers or coated with non-volatile organic substances,
It can be produced by a method of forming a metal vapor deposited film continuously while providing necessary gaps, and such a metal vapor deposition film can be formed by selecting the vapor deposition conditions and forming the metal vapor deposited film on the entire surface. This is done by, for example, cutting off before the

The above-mentioned mixture solution cast into the casting mold forming the low surface tension portion is dried at a temperature of about 40 to 100° C. under normal pressure or reduced pressure, and then dried at a temperature of about 80° C. under high vacuum. Heat and dry at ~120°C for about 24 hours.

〔Effect of the invention〕

When a polymeric acid salt and a highly ionic conductive composite are dissolved in the same solvent and cast to form a film, a cast mold is used that causes phase separation between the two. A solid polymer electrolyte membrane having a structure in which a large number of highly ionic conductive composites are arranged in a columnar manner in the thickness direction of the membrane is obtained.

This solid polymer electrolyte membrane has excellent shape retention and membrane strength because it is made of a polymeric acid salt with a volume ratio of approximately 50 to 9 brocades, and conventional solid electrolyte membranes are only a few g/aJ. The membrane is strong enough not to be distorted even under pressure of 50 kg/d or more, and the highly ionic conductive composite has a volume ratio (area ratio) of approximately 50 to 50 kg/d. 9
Because of the brocaded structure.

The decrease in conductivity also remains relatively small (within one order of magnitude).

By using such a solid polymer electrolyte membrane, the case can be constructed with only a plastic coat, whereas current batteries require a thick metal case, making the battery lighter and smaller. It is a great contribution to the achievement of this goal.

〔Example〕

Next, the present invention will be explained with reference to examples.

Example 1 A 10% by weight aqueous solution of poly(p-styrene lithium sulfonate) having a degree of polymerization of about 700 to 800 was prepared PEO composite: 24% to polyethylene oxide (PEO) having a degree of polymerization of about 40 to 45 Prepare a 10% by weight aqueous solution by adding % by weight of lithium perchlorate.Cast mold: Using a nonionic surfactant, emulsify and disperse silicone oil in 20% by volume of water. 0 in a glass petri dish
．． A mixture of 60 parts by volume of the above polymeric acid salt aqueous solution and 40 parts by volume of the PEO composite aqueous solution was cast into the above cast mold, and dried at 50°C for -15 mΩ. Thereafter, it was dried under reduced pressure conditions of 100°C, 10-'Torr, and 24 hours.

The obtained cast film has a thickness of about 300 μm, and PEO composites with an average diameter of about 60 μm are arranged on both sides at an area ratio of 3.
It was present at a rate of 5%. After staining this film with Bazacryl Blue GRL, its cross section was examined under a microscope, and it was found that most of the PEoI conjugates penetrated in the film thickness direction.

The conductivity of this film in the thickness direction (25℃) is 2X10
-'S/cm, PE0-LICQ 04 (weight ratio 7
5:25) The decrease in conductivity is suppressed to about 115 compared to 10-'S/m of the composite. Regarding film strength, in an autograph test (using a normal compression jig and compressing while observing displacement with a film thickness meter with a resolution of 1 μI), no strain was detected under a pressure of 70 kg and 7.7 kg. .

Example 2 Polymer acid salt: methyl methacrylate-sodium acrylate (molar ratio 100: about 10-15) copolymer prepared in 10% by weight dimethyl sulfoxide solution PEA composite: degree of polymerization of about 200-300 20% by weight of sodium thiocyanate was added to polyethyl acrylate (PEA) and prepared in a 10% by weight dimethyl sulfoxide solution Cast mold: Gold was sputtered on a Teflon petri dish, and the area ratio of gold was 80%. 30 m of a nearly continuous mixture of 60 parts by volume of the polymeric acid salt solution and 40 parts by volume of the PEA composite solution was cast into the above casting mold and dried at 100°C and 5 Torr. After that, it was dried under reduced pressure conditions of 120°C, 10-'Torr, and 24 hours.

The resulting cast film has a film thickness of approximately 100μ.

PEA composites having an average diameter of about 30 μm were present on both sides at an area ratio of 30%. When this film was stained with Bazacryl Blue GRL and its cross section was observed under a microscope, it was found that most of the PEA complexes penetrated in the film thickness direction.

The conductivity of this film in the thickness direction (25℃) is 2.5X
At 10-'S/am, the decrease in conductivity is suppressed to about 173 as compared to 7 x 10-'S/cm of the PEA-NaSCN (weight ratio 80:20) composite.

Regarding film strength, in an autograph test, no distortion could be detected under a pressure of 50 kg/aJ.

Claims (1)

[Claims] 1. The above polymer is applied to polyalkylene oxide or acrylic elastomer in the film thickness direction of a film formed from a polymer having an alkali metal carboxylate base or an alkali metal sulfonate bound to the side chain. A solid polymer electrolyte membrane consisting of a large number of columnar composites to which an alkali metal salt and an electrolyte substance of the same metal salt are added. 2. A composite obtained by adding an electrolyte substance of the same metal salt as the polymer alkali metal salt to a polymer having an alkali metal carboxylate base or an alkali metal sulfonate group bound to the side chain, and polyalkylene oxide or acrylic elastomer. 2. Production of a solid polymer electrolyte membrane according to claim 1, characterized in that the mixture solution is cast into a cast mold whose surface has a high surface tension and is dotted with organic matter, and dried under reduced pressure. Law. 3. A composite in which an electrolyte substance of the same metal salt as the alkali metal salt of the polymer is added to a polymer and polyalkylene oxide or acrylic elastomer having an alkali metal carboxylate base or alkali metal sulfonate bonded to the side chain. The mixture solution is cast into a cast mold in which a metal vapor deposited film is formed continuously with necessary gaps on the surface of the cast mold with low surface tension, and then dried under reduced pressure. A method for producing a solid polymer electrolyte membrane according to claim 1.