JPH04173856A - Solid polymer electrolyte - Google Patents

Abstract

PURPOSE:To provide a solid polymer electrolyte composed of ceramic fine particles having alkali metal sulfonate group, a matrix polymer and an alkali metal salt electrolyte substance, having high ionic conductance and useful for cells, various sensors, etc. CONSTITUTION:The objective solid polymer electrolyte is composed of (A) fine particles produced by bonding an alkali metal sulfonate group to the surface of fine particles of oxide ceramics (e.g. silica or alumina) having particle diameter of :<=1mum, (B) a matrix polymer having a glass transition point of <=-20 deg.C (preferably acrylic elastomer such as ethyl acrylate and 2-methoxyethyl acrylate) and (C) an alkali metal salt electrolyte substance compatible with the component B and containing the same kind of alkali metal as the metal salt of the component A (preferably perchlorate, quaternary ammonium salt, etc.). The amounts of the components A and B are 20-70vol.% and 30-80vol.%, respectively, and the amount of the component C is 0.5-60vol.% based on the composite material.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to solid polymer electrolytes. For more details,
A solid polymer electrolyte containing a matrix polymer and a salt electrolyte material.

[Conventional technology]

The present applicant has previously proposed an acrylic elastomer composition comprising an acrylic elastomer as a matrix and a mixture of the same monovalent salt of a salt electrolyte substance and a polymeric acid salt that are compatible with the acrylic elastomer (Japanese Patent Application Laid-Open No. 1999-1-1923-1). 249,851). By compounding polymeric acid salt fine particles with a solid polymer electrolyte made by dissolving a salt electrolyte substance in this acrylic elastomer, the ionic conductivity is 101 to 10-slo.
It is raised to the order of -5S-.

Furthermore, in such an acrylic elastomer composition, by using two types of polymeric acid salts, sulfonic acid type and carboxylic acid type, the 4-on conductivity can be increased from the order of lo-5S-C11-1 to 1. .8 X 1
It has been confirmed by the present applicant that it can be increased to about 0-'S-em-1 (Japanese Patent Laid-Open No. 206,640/1999).

However, at this level of ionic conductivity,
There is an aspect that its uses are limited, and further improvement of its level is desired.

[Problem to be solved by the invention]

An object of the present invention is to provide a solid polymer electrolyte containing a matrix polymer and a salt electrolyte material, which has further increased ionic conductivity.

[Means to solve the problem]

The object of the present invention is to provide oxide-based ceramic fine particles having an alkali metal sulfonate base bonded to the surface of the fine particles;
This is achieved by a solid polymer electrolyte consisting of a matrix polymer having a glass transition point of -20°C or lower and an alkali metal salt electrolyte substance that is compatible with the matrix polymer and has the same type of metal salt as the alkali metal sulfonic acid salt. .

The oxide-based ceramic fine particles having an alkali metal sulfonate base bonded to the surface of the fine particles are made of oxides such as silica, alumina, zirconia, barium titanate, etc., with a particle size of about 1μ or less, preferably about 0.001 to 0.1. The ceramic particles are boiled in concentrated sulfuric acid with a concentration of about 40% or more for about 10 minutes to about 3 hours, and after being passed through the mouth, the mixture is heated to about 100 to 200°C.
After drying for about 1 to 3 hours, washing with water, redispersing in pure water, and converting it into H+ form using an ion exchange column to remove impurity ions, lithium hydroxide, sodium hydroxide, potassium hydroxide, etc. It is obtained by immersing it in an aqueous solution of an alkali metal and converting it into an alkali metal salt.

-050. bound to the surface of the microparticles. The density of -M+ groups is high; for example, in general polymeric acid acid fine particles, the average distance of -0803-Li" on the particle surface is about 6, whereas in the case of the example described later, From a comparison of pH and surface area, the density is about 1.2 times higher.

As the matrix polymer, those having a glass transition point of 120° C. or lower and compatible with the alkali metal salt electrolyte substance, such as polyethylene oxide, polypropylene oxide, and polyphosphazene, are used, but acrylic elastomer is preferably used. It will be done.

As the acrylic elastomer, a polymer of (a) an alkyl acrylate having an alkyl group having 1 to 8 carbon atoms and/or (b) an alkoxyalkyl acrylate having an alkoxyalkyl group having 2 to 8 carbon atoms is used.

Examples of the alkyl acrylate as component (a) forming such an acrylic elastomer include methyl acrylate, ethyl acrylate, n- or iso-propyl acrylate), n- or iso-butyl acrylate, n-amyl acrylate, and An alkyl acrylate having an alkyl group having 1 to 8 carbon atoms (including those having a substituent such as a cyano group) such as xyl acrylate, 2-ethylhexyl acrylate, n-octyl acrylate, and 2-cyanoethyl acrylate is used,
Preferably ethyl acrylate or n-butyl acrylate is used.

The alkoxyalkyl acrylate of component (b) is 7, such as methoxymethyl acrylate, ethoxymethyl acrylate, 2-methoxyethyl acrylate, 2
-Alkoxyalkyl acrylate having an alkoxyalkyl group having 2 to 8 carbon atoms such as ethoxyethyl acrylate and 2-butoxyethyl acrylate is used,
Preferably, 2-methoxyethyl acrylate and 2-ethoxyethyl acrylate are used.

These components (a) and (b) are each used as a homopolymer, but generally have a polymer content of about 99.9 to 9
It is copolymerized and used at a ratio of 0 mol%, and when both components (a) and (b) are used, the former has a content of about 1% by mole.
The latter is generally used in a proportion of 0 to 90 mol %, with the latter being about 90 to 10 mol %.

A part of these components (a) and/or (b), specifically up to about 10 mol %, may be substituted with other copolymerizable monomers and copolymerized. Examples of such copolymerizable monomers include vinyl chloride, vinylidene chloride, acrylonitrile, styrene, vinyl C' acetate, ethyl vinyl ether, butyl vinyl ether, alkyl methacrylate, and alkoxyalkyl methacrylate.

Depending on the use of the acrylic elastomer, crosslinkable groups may be introduced therein. As the component forming the crosslinking points, vinyl monomers, diene monomers, etc. containing epoxy groups, carboxyl groups, reactive halogen groups, hydroxyl groups, amide groups, etc. are used.

In addition, the alkali metal salt electrolyte substances that are compatible with these matrix polymers include hydrohalic acid, perhalogenated oxyacid, halogenated oxyacid, subhalogenated oxyacid, hypohalogenated oxyacid, and tetrahalogenated oxyacid. Alkali metal salts such as boronic acid, hexahalogenated phosphoric acid, trihalogenated metasulfonic acid, thiocyanic acid, nitric acid, sulfuric acid, phosphoric acid, and carbonic acid, ammonium salts, as well as organic carboxylates, organic sulfonates, and various onium salts. Salts, quaternary ammonium salts, etc. are used, and preferably perchlorates such as lithium perchlorate, quaternary ammonium salts such as benzylpyridinium chlorite, and thiocyanates such as sodium thiocyanate and lithium thiocyanate are used. .

These alkali metal salt electrolyte substances are those in which the type of metal salt is the same as that of the alkali metal sulfonate bonded to the surface of the oxide ceramic fine particles.

In the composite formed from each of the above components, the sulfonated ceramic fine particles are present in a proportion of about 20 to 70 volume%, preferably about 30 to 60 volume%, and the matrix polymer is contained in a proportion of about 30 to 80 volume%, preferably is about 40-70% by volume, and the alkali metal salt electrolyte material is about 0.5-60% by volume, preferably about 1-60% by volume of the composite.
Each is used in a proportion of 20% by volume.

Regarding ceramic fine particles, it depends on the particle size, but
It is believed that the ionic conductivity is highest when the material originally has a close-packed structure and the matrix polymer fills the gaps, but it is also important that no pores are created during handling. The above ratio range is selected from . Regarding electrolyte substances,
Although it depends on the compatibility with the matrix polymer and the degree of adsorption on the surface of the ceramic fine particles, -
For boat fishing, a ratio within this range is used.

These composites are added into an organic solvent such as methyl ethyl ketone, dimethyl formamide, dimethyl sulfoxide, hexamethyl phosphoramide, etc. to form a slurry, which is then subjected to a casting method and then vacuum rolled.
It is formed into a film-like material using a vacuum press or the like and used as a solid polymer electrolyte.

[Operation] and [Effects of the Invention] The phenomenon of high ionic conductivity at the interface between the polymeric acid sulfonate fine particles and the matrix polymer is caused by coupling of the electrolyte substance to the sulfonate base on the surface of the fine particles, resulting in a mixed anion effect. This is thought to be due to the increase in the mobility of cations, but in the present invention, by using oxide-based ceramic fine particles with an alkali metal sulfonate base bonded to the surface of the fine particles, it is possible to combine them with the matrix polymer. and the ionic conductivity of the solid polymer electrolyte formed from the electrolyte material to 10-'S-
The value can be increased to a value close to that of em-1, making it possible to expand its uses.

Therefore, the solid polymer electrolyte of the present invention can be used in batteries.

It can be effectively used in electric double layer capacitors, electrochromic display elements, various sensors, etc.

〔Example〕

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

Example 3 Ittria fine particles containing mol% zirconia (Nippon Shokubai products; particle size 200, specific surface area 50 m2/g) 4
．． 0 g was boiled in 98% concentrated sulfuric acid for 20 minutes, passed through the mouth, dried at 200°C for 2 hours, and washed with water. This was redispersed in pure water and made into an H+ form using an ion exchange column, and then immersed in a 5% lithium hydroxide aqueous solution to make it into a Li+ form.

This lithium sulfonate salted ittria fine particles, 1.0 g of polyethyl acrylate (number average molecular weight 1.5 x 105) as a matrix, and 0.2 g of lithium perchlorate were added to 0.5++Q methyl ethyl ketone to form a slurry. The slurry was cast on a Teflon substrate at 120°C, 1O-3Torr, 2
After drying for 4 hours, vacuum press to a thickness of 10
A 0 μm film was molded.

The conductivity (20
The value obtained from the complex impedance plot at a frequency of 5 to 13 x 10'Hz) was measured at 20°C, and a value of 8.5 x 10-'5-cm was obtained.

Claims (1)

[Claims] 1. Oxide ceramic fine particles with an alkali metal sulfonate base bonded to the surface of the fine particles, glass transition point -20
A solid polymer electrolyte comprising a matrix polymer having a temperature of 0.degree.