JPS62145716A - Electrolyte for electrolytic capacitors - 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 The present invention relates to an electrolytic solution for an electrolytic capacitor.

According to the present invention, an excellent electrolytic solution for electrolytic capacitors (hereinafter sometimes simply referred to as electrolytic solution) with high conductivity can be obtained.

BACKGROUND OF THE INVENTION A well-known electrolytic solution for electrolytic capacitors is one in which an ammonium salt of boric acid or adipic acid is dissolved as a solute in an ethylene glycol solvent. Further, as an electrolytic solution having excellent low-temperature characteristics, one in which an amine salt of adipic acid or maleic acid is dissolved in a solvent such as N,N-dimethylformamide or γ-butyrolactone, which has an even lower freezing point, is known.

Problems to be Solved by the Invention However, as the impedance of electrolytic capacitors has become lower, an electrolytic solution with even higher conductivity has been desired.
9-78522 contains dibasic carboxylic acid HOOC (C
A highly conductive electrolytic solution in which a quaternary ammonium salt of nCOOH (4<n>8) is dissolved in an amide solvent containing 2 to 10% by weight of water has been disclosed, but it is not sufficient. .

Means to Solve the Problem The inventors of the present invention have conducted intensive studies to find a new electrolytic solution with even higher conductivity, and found that quaternary ammonium salts of alicyclic carboxylic acids are directly superior to conventional adipic acid, etc. The present invention was completed by discovering that the present invention exhibits higher conductivity than quaternary ammonium salts of dibasic carboxylic acids.

That is, the present invention provides an electrolytic solution for an electrolytic capacitor characterized by using a quaternary ammonium salt of an alicyclic carboxylic acid as a solute.

Effects of the Invention The quaternary ammonium salt of alicyclic carboxylic acid used as a solute in the present invention has good solubility in solvents and high conductivity, and can be used with a solvent having a wide range of freezing point to boiling point. It is an excellent electrolyte for electrolytic capacitors with a wide temperature range.

3.1 Smooth lips and bright skin The alicyclic carboxylic acid of the quaternary ammonium salt of alicyclic carboxylic acid used in the present invention is a monohydric or polyhydric carboxylic acid in the form of monocyclo and bicyclo. The size of the ring is in the range of 3 to 10 carbon atoms, and the number of carboxyl groups is 1 to 4. Further, the ring may have an unsaturated bond. The total number of carbon atoms in the alicyclic carboxylic acid ranges from 4 to 30, but preferably 6 to 12 carbon atoms.

Specifically, cyclopentanecarboxylic acid, cyclohexanecarboxylic acid, 111-cyclopentanedicarboxylic acid,
1.2-cyclopentanedicarboxylic acid, 1,1-cyclohexanedicarboxylic acid, 1.2-cyclohexanedicarboxylic acid, 4-cyclohexene-1,2-dicarboxylic acid,
Examples include 5-norbornene-2,3-dicarboxylic acid.

Examples of quaternary ammonium salts include aliphatic quaternary ammonium salts such as tetraethylammonium, tetraflobyl ammonium, tetrabutylammonium, and methyltriethylammonium; N,N-dimethylpyrrolidinium;
, N-dimethylpiperidinium, N,N-pentamethyl V
Examples include alicyclic quaternary ammonium salts such as Nbiperidinium, and aromatic quaternary ammonium salts such as N-ethylpyridinium.

Examples of the solvent for dissolving the quaternary ammonium salt of alicyclic carboxylic acid of the present invention include N-methylformamide, N-ethylformamide)', N,N-dimethylformamide,
Amide solvents such as N,N-diethylformamide, N-methylacetamide, N-ethylacetamide, N,N-dimethylacetamide, N,N-diethylacetamide, N-methylpyrrolidinone, r-butyrolactone, γ-
Noractone solvents such as valerolactone and δ-valerolactone, carbonate solvents such as ethylene carbonate, propylene carbonate, and butylene carbonate, alcohol solvents such as ethylene glycol, glycerin, and methylseron rub, nitrile solvents such as 3-methoxypropionitrile, and trimethyl Examples include phosphoric acid ester solvents such as phosphate alone or in combination. Among these, a solvent mainly composed of γ-butyrolactone is particularly preferable because it has low toxicity and is less likely to attack the sealing agent of an electrolytic capacitor and less likely to be contaminated with halogen.

The amount of the quaternary ammonium salt of alicyclic carboxylic acid dissolved in the above solvent is below the saturation concentration, preferably 5 to 40% by weight.
is within the range of Further, the dissolved salt in the electrolytic solution does not need to be a neutral salt, and may be an acidic salt.

The quaternary ammonium salt of an alicyclic carboxylic acid can be prepared by, for example, neutralizing 1 mole of the alicyclic carboxylic acid with a 1 mole aqueous solution of tetraethylammonium hydroxide, and then distilling off water under reduced pressure to obtain the product. The electrolytic solution of the present invention can also be prepared by adding an alicyclic carboxylic acid and an aqueous quaternary ammonium hydroxide solution to a solvent, dissolving it, and then dehydrating it.

The electrolytic solution of the present invention essentially consists of a quaternary ammonium salt of an alicyclic carboxylic acid and a solvent, but for the purpose of preventing galvanic corrosion, reducing leakage current, absorbing hydrogen gas, etc., various co-solutes, such as , phosphoric acid derivatives, nitrobenzene derivatives, etc. can be added.

The solvent used in the present invention can be used in a substantially anhydrous state, but for the purpose of improving electrical conductivity, improving chemical formation properties, etc.
It is also possible to add 10% by weight of water.

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

Example 1 An electrolytic solution was obtained by dissolving 20% by weight of monotetraethylammonium salt of 1,2-cyclohexanedicarboxylic acid in a γ-butyrolactone solvent.

The electrical conductivity of this electrolyte at 25°C is 8.2 mV, and the voltage is 2 m on + and - sets of aluminum smooth foil, A7/-.
The spark generation voltage when applying a constant current was 105V.

Example 2.3 In Example 1, instead of the monotetraethylammonium salt of 1,2-cyclohexanedicarboxylic acid, 1,
Conductive dust and spark generation voltage of electrolytes using 1-cyclopentanedicarboxylic acid (Example 2) and cyclohexanecarboxylic acid (Example 3) were measured. The results are shown in Table 1.

Example 4 In Example 1, instead of γ-butyrolactone, N
, the conductive dust of the electrolytic solution using N-dimethylformamide was 12.3 mS/lyn.

Example 5.6 In Example 2, instead of γ-butyrolactone, 3
Table 1 shows the conductive dust and spark generation voltage of the electrolytes using -methoxypropionitrile (Example 5) and trimethyl phosphate (Example 6).

Comparative Example 1 Table 1 shows the conductive dust and spark generation voltage of the electrolytic solution in which monotetraethylammonium salt of adipic acid was used instead of 1,2-cyclohexanedicarboxylate in Example 1.

Comparative Examples 2 to 4 20% by weight of monotetraethylammonium salt of adipic acid was added to N,N-dimethylformamide (Comparative Example 2), 3-
Methoxypropionitrile (Comparative Example 3) and trimethyl phosphate (Comparative Example 4) were dissolved in a solvent to obtain an electrolyte.

Table 1 shows the conductive dust and spark generation voltage of the electrolyte.

In addition, the following abbreviations were used in Table 1.

GBL: γ-butyrolactone DMF: N,N-dimethylformamide MPN: 3-methoxypropionitrile TMP nitrimethyl phosphate (the following margins) Table 1

Claims (1)

[Claims] (1) An electrolytic solution for an electrolytic capacitor, characterized in that a quaternary ammonium salt of an alicyclic carboxylic acid is used as a solute.