JP2002217065A - Electrolyte for driving electrolytic capacitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the electrolyte for driving an electrolytic capacitor having low specific resistance, and improved reliability at a high temperature. SOLUTION: At least one kind of dissolved substance out of adipic acid, benzoic acid, and their salt, and 0.01 to 3.0 wt.% benzoylacetone (a chemical formula 1) are added to a solvent where ethyleneglycol is mixed with 10.0 to 50.0 wt.% water.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrolytic solution for driving an electrolytic capacitor (hereinafter referred to as an electrolytic solution), and more particularly to an electrolytic solution having low specific resistance and improved reliability at high temperatures. is there.

[0002]

2. Description of the Related Art An electrolytic capacitor has a surface area enlarged by etching a high-purity aluminum foil, and a separator is interposed between an anode foil whose surface is anodized and an etched cathode foil facing the anode foil. The wound element is impregnated with an electrolytic solution, stored 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, electrode foils having a high etching magnification have been used, and tan δ of the capacitors has been increased. Therefore, an electrolytic solution having a low specific resistance has always been required.
Conventionally, as an electrolytic solution having a low cost and a low specific resistance, a solution obtained by adding water to ethylene glycol as a main solvent and further dissolving an ammonium salt such as adipic acid or benzoic acid as a solute has been used.

[0003]

However, in order to meet the demands of the market, it is necessary to further reduce the specific resistance of the electrolytic solution. To this end, it is necessary to increase the solute concentration or add a large amount of water. Must. However, when the solute concentration is increased, the solute precipitates, and when a large amount of water is added, the moisture in the electrolyte causes a hydration reaction with the electrode foil at a high temperature to generate gas, thereby increasing the internal pressure of the electrolytic capacitor. Therefore, use at 105 ° C. or more was difficult.

[0004]

In order to solve the above-mentioned problems, the present invention suppresses the hydration reaction between water and an electrode foil at a high temperature by adding benzoylacetone to an electrolytic solution, thereby reducing the specific resistance. The present invention provides an electrolytic solution having excellent reliability at high temperatures. That is, ethylene glycol and 10.0 to 5
For driving an electrolytic capacitor, characterized in that at least one solute of adipic acid, benzoic acid and a salt thereof and benzoylacetone (Chemical Formula 2) are added to a solvent mixed with 0.0 wt% of water. Electrolyte.

[0005]

Embedded image

Further, there is provided an electrolytic solution for driving an electrolytic capacitor, wherein the benzoylacetone is added in an amount of 0.01 to 3.0 wt%.

The salts of adipic acid and benzoic acid include ammonium salts, primary amine salts such as methylamine, ethylamine and t-butylamine, secondary amine salts such as dimethylamine, ethylmethylamine and diethylamine, trimethylamine and the like. Examples include tertiary amine salts such as diethylmethylamine, ethyldimethylamine, and triethylamine, and quaternary ammonium salts such as tetramethylammonium, triethylmethylammonium, and tetraethylammonium.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In an electrolyte containing water, benzoylacetone is adsorbed on the surface of an electrode foil.
The hydration reaction between water in the electrolytic solution and the electrode foil is suppressed at a high temperature, and gas generation can be suppressed even when the amount of added water increases. Further, since it is not necessary to increase the amount of the solute, the precipitation of the solute and the withstand voltage are not reduced.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be specifically described below.
An electrolytic solution was prepared according to the composition shown in Table 1, and the specific resistance at 30 ° C. was measured.

[0010]

[Table 1]

Using the electrolyte shown in Table 1, the rated voltage of 16V-4
Ten each of 700 μF (φ16 × 25 mmL) aluminum electrolytic capacitors were prepared, and the capacitance, tan δ, initial characteristics of leakage current, and capacitance change after a high-temperature load test (applied rated voltage at 105 ° C. for 1000 hours) Table 2 shows the results of investigation of the ratio, tan δ, leakage current, and appearance.

[0012]

[Table 2]

Conventional Examples 1 and 2, Comparative Examples 1 to 3 and Examples 1 to
In comparison with No. 13, an aluminum electrolytic capacitor using this example as an electrolytic solution to which benzoylacetone was added,
Although the characteristics were stable after 1000 hours at 105 ° C., the explosion-proof valve operated in a short time in the conventional example.

The amount of benzoylacetone added is 0.01
The range of -3.0 wt% is preferable. If the content is less than 0.01% by weight, the effect of benzoylacetone cannot be sufficiently obtained.
If it exceeds 0 wt%, the capacity change rate and tan
δ increases, which is a problem.

The mixing amount of water added to the electrolyte is 10.0
The range of about 50.0 wt% is preferable. If it is less than 10.0% by weight, the adsorption of benzoylacetone on the electrode foil is insufficient, and the specific resistance of the electrolytic solution does not decrease, and the
If it exceeds t%, there is a problem that the effect of benzoylacetone cannot be sufficiently obtained.

[0016]

As described above, even if a large amount of water is mixed for lowering the specific resistance, the electrolytic solution of the present invention has excellent stability at high temperatures by adding benzoylacetone, and has a high specific resistance. As a result, it is possible to improve the characteristics and reliability of the electrolytic capacitor at low cost.

Claims (2)

[Claims] (1) ethylene glycol and 10.0 to 50.
An electrolytic solution for driving an electrolytic capacitor, characterized in that at least one solute of adipic acid, benzoic acid and a salt thereof and benzoylacetone (Chemical Formula 1) are added to a solvent mixed with 0 wt% of water. . Embedded image 2. An electrolytic solution for driving an electrolytic capacitor, wherein the amount of the benzoylacetone according to claim 1 is 0.01 to 3.0 wt%.