JPS62248217A - Electrolyte for electrolytic capacitor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

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

According to the present invention, an electrolytic capacitor electrolytic solution (hereinafter sometimes simply referred to as electrolytic solution) that can be used in a wide temperature range and has high conductivity can be obtained.

Conventional technology It is well known that an electrolytic solution for electrolytic capacitors is made by completely dissolving an ammonium salt of boric acid or adipic acid as a solute in an ethylene glycol solvent. Because of its high temperature and relatively high freezing point, the conductivity of the 1-solution solution decreases significantly at low temperatures, resulting in poor low-temperature characteristics of electrolytic capacitors.

In order to improve this drawback, solvents such as N,N-dimethylformamide and γ-butyrolactone, which have a lower freezing point than ethylene glycol, have been used. However, conventional ammonium salts have poor solubility in these aprotic solvents.

Organic amine salts such as triethylamine and diethylamine have been used, but the conductivity of the electrolyte solution in all of them is very low (% Publication No. 1024/1983).

Problems to be Solved by the Invention On the other hand, JP-A-59-78522 discloses that a mixed solvent of N,N-dimethylacetamide, N-monomethylacetamide, and water (2 to 10 M%) is used.

Dibasic cargenic acid HOOC-(CH2)n-CoO
An electrolytic solution with high conductivity in which a quaternary ammonium salt of H (4'') is dissolved is disclosed. However, since this quenching liquid contains water, the vapor pressure of water increases to 7 rJ at high temperatures of 100°C or higher.

Gas is generated due to the reaction between the electrode and water, which may cause leakage of the electrolyte, which may cause reliability problems in high temperature ranges. Further, there is a problem that the IPL conductivity is low even at low temperatures of -20°C or lower.

Means for Solving the Problems The present invention eliminates the above-mentioned drawbacks and consists of a quaternary ammonium salt of an aliphatic saturated dicarboxylic acid having a total of 2 to 10 carbon atoms dissolved in a solvent mainly composed of γ-butyrolactone. The present invention provides an electrolytic solution for an electrolytic capacitor, which is characterized in that it does not contain water.

Effects of the Invention The electrolytic solution of the present invention has high conductivity over a wide temperature range and is substantially free of water, so a capacitor using this electrolytic solution can be used over a wide temperature range of about -40°C to 125°C. It is possible.

DETAILED DESCRIPTION OF THE INVENTION In the present invention, γ-butyrolactone is used as a solvent. γ
-Butyrolactone has advantages such as a wide usable temperature range with a freezing point of -44°C and a boiling point of 204°C, low toxicity, and little attack by sealants.

In the quaternary ammonium salt of an aliphatic saturated dicarboxylic acid having a total of 2 to 10 carbon atoms used in the present invention, the aliphatic saturated dicarboxylic acid refers to a linear and branched aliphatic saturated dicarboxylic acid having a total of 2 to 10 carbon atoms. Examples of acids include oxalic acid, malonic acid, succinic acid, glutaric acid, anovic acid, pimelic acid, superric acid, azelaic acid, cepacic acid, methylsuccinic acid, j-? Lucuccinic acid%2,2
-dimethylsuccinic acid, 2,3-trimethylsuccinic acid, 2-
Examples include methylglutaric acid, 3-methylglutaric acid, 3,3-dimethylglutaric acid, 3-methyladipic acid, 3-methyl-3-ethylglutaric acid, and 3,3-diethylglutaric acid.

Examples of quaternary ammonium salts include tetraethylammonium, tetrapropylammonium, tetrabutylammonium, methyltriethylammonium, methyltriglopylammonium, methyltributylammonium,
Dimethylsoethylammonium, dimethyldiglobylammonium, dimethyldiptylammonium.

Aliphatic quaternary ammonium salts such as ethyltripropylammonium and ethyltributylammonium, N, N-
Dimethylpyrrolidinium, N,N-dimethylpiperidinium, N-methyl-N-ethylpyrrolidinium, N-
Examples include alicyclic quaternary ammonium salts such as methyl-N-ethylpiperidinium and N,N-pentamethylenepiperidinium, and aromatic quaternary ammonium salts such as N-ethylpyrizonium.

The bath decomposition of the above solute is less than the saturation strength, preferably 5 to 40.
% by weight. Further, the molar ratio of acid and base in the dissolved salt of the electrolytic solution is used in a range of 1:2 to 2:1.

Quaternary ammonium salts of straight-chain and branched aliphatic saturated dicarboxylic acids can be used, for example, in their carboxylic acids. After neutralizing the phosphoric acid with an aqueous solution of quaternary amsonium hydroxide, the water is distilled off under reduced pressure and the product is dried under vacuum.

The 4-solution solution of the present invention is prepared by adding the aliphatic dicarboxylic acid and the entire quaternary ammonium hydroxide bath solution to the solvent, and after the neutralization reaction, dehydration and F
AJJ! You can also do it.

The '1 solution of the present invention essentially consists of a γ-butyrolactone solvent and an aliphatic saturated radical having a total of 2 to 10 carbon atoms. The quaternary ammonium salts are different from each other.

'For the purpose of preventing galvanic corrosion, reducing leakage current, absorbing hydrogen gas, etc., various co-solutes such as phosphoric acid derivatives, nitrobenzene-conductors, etc. can be added.

Moreover, a non-aqueous co-solvent can also be used for the purpose of lowering the freezing point and improving the electrical conductivity by lowering the viscosity.

EXPERIMENTAL EXAMPLES The present invention will be explained in more detail below with reference to Examples and Comparative Examples.

Example 1 A gold electrolyte was obtained by dissolving 20 parts by weight of sebacic acid monotetraethylammonium salt in a γ-butyrolactone solvent. The conductivity of this electrolyte at 25°C is 5.20 m
With s/cIR, a spark is generated when a constant current of 4 mA/'cys'' is applied to the aluminum smooth foil of j), +, and - pairs.
1 pressure was 215v.

Examples 2 to 7 In Example 1, instead of the monotetraethylammonium salt of sepacic acid, superic acid (Example 2), azopic acid (Example 3), glutaric acid (Example 4), co-phosphoric acid ( Example 5).

Malonic acid (Example 6), oxalic acid (Example 7).

Monotetraethylammonium of 2-methylglutaric acid (Example 8), 3-methylglutaric acid (Example 9), 3,3-methylglutaric acid (Example 10), and 3-methyladipic acid (Example 11) Table 1 shows the conductivity and spark generation voltage of the electrolyte using salt.

Comparative Example 1 In Example 1, monotriethylammonium salt of sepacic acid was used instead of monotriethylammonium salt of sepacic acid.
However, it had low conductivity and was unsuitable as an electrolyte for electrolytic capacitors.

Comparative Example 2 In Example 1, instead of the r-butyrolactone solvent, a mixed solvent of N,N-methylacetamide and N-methylacetamide (molar ratio 4:1) was used, and water was
The conductivity and spark generation voltage of the electrolytic solution to which 1 t-1 weight was added were measured. The results are shown in Table 1.

In Table 1, the following abbreviations were used.

GBL: r-butyrolactone DMA: N,N-dimethylacetamide NMA:
N-Monomethylacetamide Example 12 and Comparative Example 3 Electrical conductivity (m,
/, -, ) are shown in Table 2.

Table 2

Claims (1)

[Claims] A total of 2 to 2 carbon atoms in a solvent mainly composed of r-butyrolactone
1. An electrolytic solution for electrolytic capacitors, characterized in that it is substantially free of water and contains a quaternary ammonium salt of an aliphatic saturated dicarboxylic acid of No. 10 dissolved therein.