JPH09213577A - Electrolyte for driving electrolytic capacitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To restrain hydration reaction between water in electrolyte and an electrode foil at a high temperature, and suppress gas generation, by dissolving at least one kind of organic carboxylic acid or its salt out of adipic acid and benzoic acid in aqueous solution of ethylene glycol, and adding L-leucine to the solution. SOLUTION: At least one kind of organic carboxylic acid or its salt out of adiplc acid and benzoic acid is dissolved, as solute, in solvent wherein ethylene glycol and water of 10-20wt.% are mixed. L-leucine of 0.01-3.0wt.% is added to the solution. Even when loadings of water is increased, low resistivity electrolyte excellent in stability at a high temperature is obtained. Thereby characteristics and reliability of an electrolytic capacitor can be improved at a low cost.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in an electrolytic solution for driving an electrolytic capacitor (hereinafter simply referred to as an electrolytic solution), and more particularly to an electrolytic solution having excellent conductivity and stable at high temperature.

[0002]

2. Description of the Related Art Generally, an electrolytic capacitor is formed by etching a high-purity aluminum foil to increase its surface area and anodizing its surface to make it a dielectric, and an etched cathode foil facing the anode foil. An element having a structure in which a separator paper is wound between the elements is impregnated with an electrolytic solution, housed in a case, and sealed with a sealing body. In such an electrolytic capacitor, the characteristics of the electrolytic solution are a major factor in determining the performance of the electrolytic capacitor. In particular, with the recent miniaturization of electrolytic capacitors, those with a high etching rate have come to be used, and the resistivity of capacitors has increased. Therefore, the electrolytic solution used for this must always have a low specific resistance. Required. Among the conventional electrolytes, the one with low cost and low specific resistance is ethylene glycol as the main solvent, water is added to this, and further ammonium salts of carboxylic acids such as adipic acid and benzoic acid are dissolved as electrolytes. Things are being used.

[0003]

However, although such an electrolytic solution can reduce the specific resistance, since the amount of water added is large, the water in the electrolytic solution undergoes a hydration reaction with the electrode foil at high temperatures. As a result, gas is generated and the internal pressure of the electrolytic capacitor rises, so it was difficult to use at 105 ° C or higher.

[0004]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention comprises ethylene glycol and 10 to 20 wt. %
0.01 to 3.0 of L-leucine in a solvent prepared by dissolving at least one organic carboxylic acid or its salt among adipic acid and benzoic acid as a solute in a solvent mixed with water.
wt. %.

[0005]

By adding L-leucine, even if the amount of water added increases, the hydration reaction between water in the electrolytic solution and the electrode foil is suppressed at a high temperature of 105 ° C., and gas generation is suppressed.

As a result of various studies on the amount of L-leucine added, 0.01 to 3.0 wt. It was good within the range of%. 0.01 wt. If it is less than%, the suppressing effect does not appear, and 3.
0 wt. If it exceeds%, the breakdown voltage will decrease.

The amount of water added is 10 to 20 wt. % Range, 10 wt. If it is less than%, the specific resistance does not decrease, and
wt. If it exceeds%, the above-mentioned effects due to L-leucine will not appear.

Embodiments of the present invention will be described below. Table 1 shows the electrolytic solution according to the present invention (sample symbols a, b, c, d,
e, f, g, h, i, j) and the composition ratio of each of the conventional electrolytic solutions (sample symbols A, B, C, D) for comparison, and the ratio of the electrolytic solutions at 30 ° C. Indicates resistance.

[0008]

[Table 1]

In addition, Table 2 shows the results of 50 aluminum electrolytic capacitors prepared by using each of the above electrolytic solutions and subjected to a load test at 105 ° C. for 1000 hours. All capacitor samples are aluminum electrolytic capacitors rated at 10V and 4700 μF.

[0010]

[Table 2]

The aluminum electrolytic capacitors using the conventional electrolytic solutions (A, B, C, D) generate a large amount of gas, and the explosion-proof valve is activated in a short time. Electrolyte solution according to the present invention (sample symbols a, b, c, d, e, f, g, h, i, j)
Aluminum electrolytic capacitor using
It shows stable characteristics even after 00 hours.

[0012]

As described above, in the present invention, the addition of L-leucine makes it possible to obtain an electrolytic solution having excellent stability at high temperatures and low specific resistance even when the amount of water added is large. Therefore, it is possible to improve the characteristics and reliability of the electrolytic capacitor at low cost, which is of great industrial and practical value.

Claims (3)

[Claims] 1. An organic carboxylic acid of at least one of adipic acid and benzoic acid or a salt thereof is dissolved as a solute in a solvent mixture of ethylene glycol and water, and L-leucine is added to the solution. Characteristic electrolytic solution for driving electrolytic capacitors. 2. The amount of L-leucine added is from 0.01 to
3.0 wt. %, The electrolytic solution for driving the electrolytic capacitor according to claim 1. 3. The amount of water added is 10 to 20 wt. %
The electrolytic solution for driving the electrolytic capacitor according to claim 1 or 2.