JPH0950941A - Electrolyte solution for driving electrolytic capacitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrolytic solution for driving an electrolytic capacitor with good electric conductivity and no leak of solution. SOLUTION: In an electrolyte solution, carboxylic acid-based salt of 1,2- dimethyl 1,4,5,6-tetrahydropyrimidine or 1,2-dimethyle-4,5-dihydroimidazole is dissolved in a γ-butyrolactone-based solvent.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrolytic capacitor driving electrolytic solution and an electrolytic capacitor using the electrolytic solution.

[0002]

2. Description of the Related Art A high-frequency, low-impedance aluminum electrolytic capacitor has a high electrical conductivity obtained by using a quaternary ammonium salt of a carboxylic acid such as phthalic acid or maleic acid as a solute in a solvent containing γ-butyrolactone as a main component. (Japanese Patent Laid-Open Nos. 62-145713 and 62-145715) are used. However, these quaternary ammonium salt-based electrolytes have a problem in that the base component may leak from the cathode part, resulting in poor reliability (Sato, Journal of Japan Reliability Society, Vol. 17, No. 3, p. 54). 1
995).

In order to avoid this liquid leakage problem, therefore, a highly reliable tertiary ammonium salt-based electrolytic solution having a low electric conductivity but no liquid leakage problem (Japanese Patent Laid-Open No. 54-54).
-7564 and 61-70711). As one of such electrolytic solutions, an electrolytic solution using a diazabicycloalkene salt as a solute (Japanese Patent Laid-Open No. 62-9618) has been attracting attention, but it has a higher electric conductivity than a quaternary ammonium salt-based electrolytic solution. Since the conductivity is low, it is desired to develop an electrolytic solution having higher electric conductivity.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an electrolytic solution which is free from liquid leakage problems and has high reliability and high electric conductivity.

[0005]

The present invention provides a solvent containing a γ-butyrolactone solvent as a main component with 1,2-dimethyl-
1,4,5,6-tetrahydropyrimidine or 1,2
-Provides an electrolytic solution for driving an electrolytic capacitor obtained by dissolving a carboxylic acid salt of dimethyl-4,5-dihydroimidazole.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is described in detail below. (1) Solvent The solvent used in the present invention is γ-butyrolactone alone or a mixture of γ-butyrolactone as a main component with another sub-solvent. Specific examples of the sub-solvent include N-methylformamide, N-ethylformamide, N, N-dimethylformamide, N, N-diethylformamide,
Amide solvents such as N-ethylacetamide, N, N-dimethylacetamide and N-methylpyrrolidinone; lactone solvents such as γ-valerolactone and δ-valerolactone; ethylene carbonate, propylene carbonate,
A carbonate solvent such as butylene carbonate; an alcohol solvent such as ethylene glycol, glycerin and methyl cellosolve; a nitrile solvent such as 3-methoxypropionitrile and glutaronitrile; a phosphate ester solvent such as trimethyl phosphate and triethyl phosphate; these two types A mixture of the above solvents can be used. Among these, ethylene glycol is preferable from the viewpoint of electric conductivity. The amount of such an auxiliary solvent added is preferably 1 to 15% by weight. The concentration of the solvent in the electrolyte is 6
0 to 95% by weight.

(2) Solute The solute is 1,2-dimethyl-1,4,5,6-tetrahydropyrimidine or 1,2-dimethyl-4,5-dihydroimidazole carboxylate. Examples of such carboxylic acids include unsaturated aliphatic dicarboxylic acids such as maleic acid, citraconic acid, dimethylmaleic acid and 1,2-cyclohexenedicarboxylic acid; oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, dimethyl. Malonic acid, diethylmalonic acid, 2-methylglutaric acid, 3-
One or more selected from saturated aliphatic dicarboxylic acids such as methylglutaric acid and 3,3-dimethylglutaric acid; aromatic dicarboxylic acids such as phthalic acid and 4-nitrophthalic acid; aromatic monocarboxylic acids such as benzoic acid and salicylic acid Mention may be made of carboxylic acids. Among these, maleic acid and phthalic acid are preferable from the viewpoint of electrical conductivity. These amidine carboxylates may be used alone or in admixture of two or more. The carboxylic acid salt may be a mono-salt or a di-salt, but the mono-salt is preferred. The solute concentration in the electrolytic solution is 5 to 40% by weight.

(3) Optional components The electrolytic solution for driving an electrolytic capacitor of the present invention contains various co-solutes such as phosphorus compounds and nitroaromatic compounds for the purpose of reducing leakage current, absorbing hydrogen gas, improving withstand voltage and the like. , Boric acid, hexites, colloidal silica and the like can be added. Further, 1 to 5% by weight of water can be added for the purpose of improving electric conductivity and chemical conversion.

[0009]

【Example】

Example 1 To 75 parts by weight of γ-butyrolactone, 25 parts by weight of 1,2-dimethyl-1,4,5,6-tetrahydropyrimidine hydrogen maleate salt as a solute (indicated as DMTHP hydrogen maleate salt in Table 1). Was blended to prepare an electrolytic solution. The electrical conductivity of this product at 25 ° C is 9.1 mS /
cm. Also, aluminum foil is used at a current density of 5 mA / cm ²
The spark voltage measured by performing constant current formation at
It was 0 volt. Further, when an aluminum electrolytic capacitor having a rating of 50 WV and 150 μF was manufactured as a prototype and examined for liquid leakage, no liquid leakage was found.

Examples 2 to 4 and Comparative Examples 1 to 3 Electrolyte solutions having the compositions shown in Table 1 were prepared and the performance was evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0011]

[Table 1]

[0012]

Embedded image

[0013]

EFFECTS OF THE INVENTION Since an electrolytic solution having a high electric conductivity can be obtained by the present invention, by using this electrolytic solution, a highly reliable electrolytic capacitor having a high frequency and a low impedance with no liquid leakage can be obtained.

Claims (3)

[Claims] 1. A carboxylic acid salt of 1,2-dimethyl-1,4,5,6-tetrahydropyrimidine or 1,2-dimethyl-4,5-dihydroimidazole is added to a solvent containing γ-butyrolactone as a main component. Dissolved electrolytic solution for driving electrolytic capacitors. 2. A mixed solvent comprising 85 to 99% by weight of γ-butyrolactone and 15 to 1% by weight of ethylene glycol is added to 1,2-dimethyl-1,4,5,6-tetrahydropyrimidine or 1,2-dimethyl-. An electrolytic solution for driving an electrolytic capacitor obtained by dissolving a carboxylic acid salt of 4,5-dihydroimidazole. 3. The electrolytic solution for driving an electrolytic capacitor according to claim 1, wherein the carboxylic acid is maleic acid and / or phthalic acid.