JPH0992328A - Gelled electrolyte - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gelled electrolyte which has a high ion conductivity applicable to various electrochemical elements, is thermally and electrochemically stable, and has a gel strength conformable to the miniaturization and thinning of electrochemical elements. SOLUTION: This gelled electrolyte contains the following components (a), (b) and (c). The component (a), which forms the matrix of the gelled electrolyte, ensures a sufficient get strength by use of a thermoplastic elastomer obtained by block-copolymerizing a polyether or fatty polyester as soft segment with a polyamide or aromatic polyester as hard segment. The component (b) is a gelled polar organic solvent such as ethylene carbonate. The component (c) is an electrolyte ionized in the polar organic solvent of the component (b) to show ion conductivity such as alkali earth metal salt.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a gel electrolyte composition which can be applied to electrochemical devices such as lithium primary batteries, secondary batteries, electrolytic capacitors and electrochromics.

[0002]

2. Description of the Related Art In recent years, as electronic equipment has become smaller and thinner, electrochemical elements such as lithium primary batteries, secondary batteries, electrolytic capacitors, and electrochromics used in electronic equipment have also become smaller and thinner. It has been demanded. In these electrochemical devices, an electrolytic solution is used as an ion conductive material. Usually, these electrolytes are liquids in which an electrolyte is dissolved in water or an organic solvent. However, the liquid electrolyte may leak when the electrochemical device is used unless a sufficient sealing means is used, and the characteristics of the electrochemical device are deteriorated, and there is a problem in safety. It is not suitable for thinning and thinning.

In order to improve the drawbacks of the liquid electrolytic solution, a method of adding a gelling agent to the electrolytic solution to form a gel is known. By making the electrolytic solution into a gel, there is no fear of liquid leakage, and the electrolytic solution can be made into a flexible sheet, which is suitable for downsizing and thinning of the electrochemical element. Conventionally known gelling agents used for gel electrolytes are natural products such as gelatin and agar, derivatives of natural products such as hydroxyethyl cellulose, and synthetic polymer compounds such as polyvinyl alcohol, poly (meth) acrylate, and polyethylene oxide. ing.

[0004]

The properties required of the gel electrolyte are high ionic conductivity, thermal and electrochemical stability, and can be applied to miniaturization and thinning of electrochemical devices. It is necessary to have gel strength capable of molding into such a flexible sheet. However, the conventional gel electrolytes using a conventional gelling agent have insufficient gel strength, insufficient ionic conductivity, and none satisfying all the above characteristics.

The problem to be solved by the present invention is that it can be applied to various electrochemical devices, has high ionic conductivity, is thermally and electrochemically stable, and is small in size. It is to provide a gel electrolyte having a gel strength capable of coping with reduction in thickness and thickness.

[0006]

As a result of intensive studies to solve the above problems, the present inventor has found that a specific thermoplastic elastomer may be used as a gelling agent, and completes the present invention. Came to.

That is, the present invention relates to (a) a thermoplastic elastomer obtained by block-copolymerizing a polyether or an aliphatic polyester as a soft segment and a polyamide or an aromatic polyester as a hard segment,
The present invention relates to a gel electrolyte containing (b) a polar organic solvent and (c) an electrolyte.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION As described above, the gel electrolyte of the present invention essentially contains the three components (a), (b) and (c).

First, the component (a) serves as a matrix of the gel electrolyte of the present invention, and block-copolymerizes the polyether or aliphatic polyester as a soft segment and the polyamide or aromatic polyester as a hard segment. By using a thermoplastic elastomer, sufficient gel strength can be secured.
Even in the form of a thin sheet having a thickness of up to 200 μm, sufficient performance as an electrolyte can be secured. Examples of the polyether or aliphatic polyester that constitutes the soft segment of the thermoplastic elastomer include 1,4-butanediol and poly (oxytetramethylene) glycol. On the other hand, examples of the polyamide or aromatic polyester that constitutes the hard segment of the thermoplastic elastomer include 12 nylon and terephthalic acid.

Component (b) is a polar organic solvent, and (c)
Dissolve the component electrolyte and ionize the electrolyte ions, (a)
It is not particularly limited as long as it forms a gel with the thermoplastic elastomer as a component, but for example, ethylene carbonate, propylene carbonate, dimethyl sulfoxide, sulfolane, γ-butyrolactone, N, N-dimethylformamide, acetonitrile, nitromethane, N-
Methylpyrrolidone, tetrahydrofuran, 1,2-dimethoxyethane, 1,3-dioxolane, 2-methoxytetrahydrofuran, diethyl ether, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, diethylene glycol dimethyl ether, ethylene glycol dimethyl ether and formamide. .

The component (c) is an electrolyte and is not particularly limited as long as it exhibits ion conductivity by ionizing ions in the polar organic solvent of the component (b). For example, LiCl
O ₄ , LiBF ₄ , LiAlCl ₄ , KSCN, NaSC
Alkali metal salts such as N, Ca (ClO ₄ ) ₂ , Zn (SC
Examples thereof include alkaline earth metal salts such as N), tertiary ammonium salts such as triethylamine phthalate, and quaternary ammonium salts such as tetraethylammonium phthalate. These electrolytes can be used alone or in appropriate combination of two or more kinds.

In order to maintain high ionic conductivity and gel strength in the gel electrolyte of the present invention, (a),
The blending ratios of the respective components of (b) and (c) are (a),
It may be adjusted within the following range so that the total amount of the components (b) and (c) is 100 wt%.

Component (a): 10 to 80 wt% (b) Component: 15 to 80 wt% (c) Component: 1 to 10 wt% To produce the gel electrolyte of the present invention, the electrolyte of (c) is used (b). ) In a polar organic solvent to prepare an electrolytic solution,
The thermoplastic elastomer (a) may be added thereto, and the mixture may be heated and melted at a temperature equal to or higher than the melting point of the thermoplastic elastomer to prepare an electrolyte solution, which may be coated into a film or molded by casting and cooled.

Further, a solution in which the thermoplastic elastomer (a) is dissolved in an organic solvent having a low boiling point (bp 40 to 110 ° C.) such as methylene chloride or toluene is prepared, and the electrolyte (b) is added to the solution (b). The electrolytic solution prepared by dissolving in a polar organic solvent of 1) may be added and mixed, and after molding by coating or casting, the low boiling point organic solvent may be volatilized to produce a gel electrolyte.

Since the gel electrolyte of the present invention has high ionic conductivity and gel strength, it can be formed into a highly flexible sheet or film. The gel electrolyte of the present invention can be used as an electrolyte for electrochemical devices such as lithium primary batteries, secondary batteries, electrolytic capacitors, and electrochromics, and it is possible to reduce the size and thickness of these electrochemical devices. You can

[0016]

【Example】

Example 1 An electrolyte was prepared by adding and dissolving an electrolyte in the polar solvent shown in Table 1 with stirring. Next, the thermoplastic elastomers shown in Table 1 were added and heated and dissolved to prepare an electrolyte solution. The obtained electrolyte solution was cast on a glass plate to produce a 100 μm film. The volume resistance and gel state of the obtained gel electrolyte were measured. The measured results are shown in Table 1.

[0017]

[Table 1]

Example 2 The thermoplastic elastomer shown in Table 2 was dissolved in a low boiling point organic solvent with stirring, while the electrolyte was dissolved in the polar organic solvent shown in Table 2 to prepare an electrolytic solution. Then, the low boiling point organic solvent solution of the thermoplastic elastomer and the electrolytic solution are mixed, and the obtained mixed solution is cast on a glass plate, and then 50
Dry for 1 hour at ℃, form a film of 40μm,
A gel electrolyte was prepared. The volume resistance and gel state of the obtained gel electrolyte were measured. The measurement results are shown in Table 2.

[0019]

[Table 2]

From the results shown in Tables 1 and 2, the gel electrolyte of the present invention has high ionic conductivity and gel strength, and can be formed into a highly flexible film or sheet. Is.

[0021]

The gel electrolyte of the present invention has high ionic conductivity and gel strength, and can be used as an electrolyte for electrochemical devices such as lithium primary batteries, secondary batteries, electrolytic capacitors and electrochromics. Since the use of a separator is not necessary, it is possible to contribute to downsizing and thinning of these electrochemical elements.

Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI Technical indication location G02F 1/15 G02F 1/15 H01G 9/035 H01M 6/18 E H01M 6/18 6/22 C 6/22 H01G 9/02 311

Claims (3)

[Claims] 1. A thermoplastic elastomer containing (a) a polyether or aliphatic polyester as a soft segment and block copolymerized with a polyamide or an aromatic polyester as a hard segment, (b) a polar organic solvent and (c) an electrolyte. A gel electrolyte characterized by being. 2. The polar organic solvent is ethylene carbonate, propylene carbonate, dimethyl sulfoxide,
Sulfolane, γ-butyrolactone, N, N-dimethylformamide, acetonitrile, nitromethane, N-methylpyrrolidone, tetrahydrofuran, 1,2-dimethoxyethane, 1,3-dioxolane, 2-methoxytetrahydrofuran, diethyl ether, ethylene glycol, diethylene glycol, Triethylene glycol,
The gel electrolyte according to claim 1, which is at least one selected from polyethylene glycol, diethylene glycol dimethyl ether, ethylene glycol-dimethyl ether, and formamide. 3. The gel electrolyte according to claim 1, wherein the electrolyte is at least one selected from alkali metal salts, alkaline earth metal salts, tertiary ammonium salts and quaternary ammonium salts.