JPH02263423A - Electrolyte for electrolytic capacitor drive use - Google Patents

Abstract

PURPOSE:To obtain an electrolyte, which has a high specific conductance and is stable at a high temperature, by a method wherein the quaternary ammonium salt of a tetronic acid and/or an alpha-methyltetronic acid is used as a solute. CONSTITUTION:Quaternary ammonium salt of a tetronic acid and/or an alpha- methyltetronic acid is used as a solute. The content of the quaternary ammonium salt of the tetronic acid and/or the alpha-methyltetronic acid is normally 1 to 50%, desirably 10 to 40%, on the basis of the weight of an electrolyte. Thereby, the electrolyte shows a high specific conductance and at the same time, as the electrolyte is stable even after a high-temperature treatment, a reduction in the loss of an electrolytic capacitor using this electrolyte is possible and moreover, the deterioration of the capacitor at the time of a high temperature is improved and the prolongation of the longevity of the capacitor can be attained.

Description

[Detailed description of the invention] Industrial applications The present invention relates to an electrolytic solution for driving an electrolytic capacitor.

Conventional technology Conventionally, as an electrolytic solution for driving an electrolytic capacitor, a quaternary ammonium salt of an aromatic carboxylic acid (phthalic acid, etc.) is used as a solute (Japanese Patent Application Laid-Open No. 62145715), a quaternary ammonium salt of maleic acid, etc. salt as a solute (JP-A-62145713), a quaternary ammonium salt of an aliphatic saturated monocarboxylic acid (formic acid, etc.) as a solute (
JP-A No. 62-226614) and one using a quaternary ammonium salt of an aliphatic saturated dicarboxylic acid (such as malonic acid) as a solute (JP-A No. 62-248217) are known.

Problems to be Solved by the Invention However, those using a quaternary ammonium salt of phthalic acid as a solute have insufficient specific conductivity.

Those using quaternary ammonium salts such as maleic acid, formic acid, and malonic acid as solutes have insufficient stability at high temperatures and gas generation is also observed.

Means for Solving the Problems The inventors of the present invention have arrived at the present invention as a result of extensive research aimed at creating an electrolytic solution that has a high specific conductivity and is stable at high temperatures.

That is, the invention is an electrolytic solution for driving an electrolytic capacitor characterized in that a quaternary ammonium salt of tetronic acid and/or α-methyltetronic acid is used as a solute.

In the present invention, quaternary ammonium salts include tetraalkyl (the number of carbon atoms in the alkyl group is usually 1 to 12) ammonium (tetramethylammonium, tetraethylammonium, tetrapropylammonium, tetrabutylammonium, methyltriethylammonium, dimethyldiethylammonium, ethyltrimethylammonium), aryltrialkylammonium (such as phenyltrimethylammonium), cyclohexyltrialkylammonium (such as cyclohexyltrimethylammonium), arylalkyltrialkylammonium (such as arylalkyltrialkylammonium) and N,N-dialkylpiperidinium (N,N- (dimethylpiperidinium, etc.) and mixtures thereof. Among these, preferred are tetraalkylammonium salts. Particularly preferred are asymmetric (all four alkyl groups are not the same) tetraalkylammonium salts. Asymmetric tetraalkylammonium salts have good solubility in solvents and can easily have high conductivity. Among the above-mentioned salts, examples of the asymmetric tetraalkylammonium salt include methyltriethylammonium and dimethyldiethylammonium salts.

The molar ratio of tetronic acid and/or α-methyltetronic acid to quaternary ammonium is usually 0.5 to 1.6, preferably 0.8 to 1.2.

Specific examples of the salt in the present invention include the following.

1 Salt of tetronic acid and methyltriethylammonium (molar ratio 1.0) boiled 2 Salt of α-methyltetronic acid and methyltriethylammonium (molar ratio 1.0)
．． o) Such salts are easily synthesized, for example, by reaction with methyltriethylammonium hydroxide.

The electrolytic solution of the present invention consists of a salt and a solvent (usually an organic solvent).

Examples of this organic solvent include alcohols (1f [f
i Alcohol (methyl alcohol, ethyl alcohol,
Propyl alcohol, methyl alcohol, diacetone alcohol (ethylene glycol, propylene glycol, diethylene glycol, hexyl alcohol, etc.); trihydric alcohol (glycerin, etc.); hexitol), ethers (monoether (ethylene glycol, etc.); glycol monomethyl ether, ethylene glycol monoethyl ether,
Diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, ethylene glycol phenyl ether); diethers (ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, etc.)), amides (
Formamides (N-methylformamide, N,N-dimethylformamide, N-ethylformamide, N,N
-diethylformamide, etc.); acetamides (N-
Methylacetamide, N,N-dimethylacetamide,
N-ethylacetamide, N,N-diethylacetamide, etc.); propionamides (N,N-dimethylpropionamide, etc.); hexamethylphosphorylamide, etc.), oxazolidinones (N-methyl-2-oxazolidinone, 3,5- dimethyl-2-oxazolidinone, etc.), lactones (γ-butyrolactone, α-acetyl-γ-butyrolactone, β-butyrolactone, γ-valerolactone, etc., δ-valerolactone, etc.), nitriles (acetonitrile, acrylonitrile, etc.), dimethyl sulfoxide, Sulfolane, 1,3-dimethyl-2-
Examples include imidazolidinone, N-methylpyrrolidone, aromatic solvents (toluene, xylene, etc.), paraffinic solvents (normal paraffin, imparaffin, etc.), and mixtures of two or more of these. Among these, preferred is a solvent mainly composed of γ-butyrolactone.

The electrolytic solution of the present invention can also contain water if necessary. Its content is usually less than 10% based on the weight of the electrolyte.

In the electrolytic solution of the present invention, tetronic acid and/or α
- The content of the salt of methyltetronic acid is usually 1 to 50%, preferably 10 to 40%, based on the weight of the electrolyte.

Function: The electrolytic solution of the present invention consists of a salt of tetronic acid and/or α-methyltetronic acid and a solvent, but various additives may be added for the purpose of reducing leakage current and absorbing hydrogen gas. can do. As additives, mention may be made of phosphoric acid derivatives, boric acid derivatives and nitro compounds.

EXAMPLES Hereinafter, the present invention will be further explained with reference to Examples, but the present invention is not limited thereto. The numbers in the examples are based on weight.

Examples 1-2 and Comparative Examples 1-4 25 of the salts (electrolytes) shown in the present invention shown in Table-1
% γ-butyrolactone solution and an electrolytic solution of a comparative example (25% γ-butyrolactone solution) were prepared, and their specific conductivities (30'C1m5/cm) were measured at the initial stage and after heat treatment (150°C). , 6 hours). Also,
The presence or absence of gas generation during heat treatment was observed. Table the results.
Shown in 1.

Table 1 (Note) (1) AI and A2 indicate the specific examples of the salts used in the present invention. Indicates ammonium salt.

Effects of the Invention The electrolytic solution of the present invention exhibits high specific conductivity and is stable even after high-temperature treatment. Therefore, an electrolytic capacitor using the electrolytic solution of the present invention can have low loss and is stable even at high temperatures. deterioration is improved and a longer life is achieved.

Claims (2)

[Claims] (1) An electrolytic solution for driving an electrolytic capacitor, characterized in that a quaternary ammonium salt of tetronic acid and/or α-methyltetronic acid is used as a solute. (2) An electrolytic solution for driving an electrolytic capacitor, characterized in that an asymmetric quaternary ammonium salt of tetronic acid and/or α-methyltetronic acid is used as a solute.