JPH0361329B2 - - Google Patents

Description

[Detailed description of the invention]

(a) Industrial Application Field The present invention relates to an electrolytic solution for driving an electrolytic capacitor. (b) Prior art At present, the driving electrolyte for electrolytic capacitors uses ethylene glycol as the main solvent, organic acids such as adipic acid, formic acid, and benzoic acid, and their salts, and/or inorganic acids such as boric acid and phosphoric acid. Many are used that have solutes such as or their salts. By the way, this type of conventional capacitor using a driving electrolyte has a problem in that the viscosity of the electrolyte increases at low temperatures such as -55° C., resulting in deterioration of characteristics. Therefore, in order to solve this problem,
For example, as shown in Japanese Patent Publication No. 55-39898 (H01G9/02), N-ethylformamide is used as a solvent and 5 g or more of an acid salt of maleic acid is included as a solute per 100 g of the solvent; −
A method using a mixed solvent of methyl alcohol and dimethyl sulfoxide is known, as shown in Publication No. 57854 (H01G9/02). (c) Problems to be solved by the invention The above-mentioned Japanese Patent Publication No. 55-39898 and Japanese Patent Publication No. 57-
When the driving electrolyte shown in Publication No. 57854 is used, the low-temperature characteristics are improved, but when a load test is performed at a high temperature such as 105°C, the driving electrolyte is removed from the capacitor during the load test. The capacitor's characteristics deteriorate because it passes through the sealing material used to seal the element in the metal case and escapes to the outside. On the other hand, adding water to the driving electrolyte can also improve low-temperature characteristics, but in this case there is a problem that the sealing material will expand at high temperatures such as 105°C, and in the worst case, it will be destroyed. . (d) Means for Solving the Problems In view of the above problems, the present invention provides 30 to 90% by weight of ethylene glycol and 70 to 90% by weight of N-ethylformamide.
The present invention provides an electrolytic solution for driving an electrolytic capacitor, characterized in that acetic acid or a salt thereof and adipic acid or a salt thereof are dissolved in a mixed solvent consisting of 10% by weight. (e) Effects According to the present invention, there is little characteristic deterioration during low temperature and high temperature load tests, and high pressure use is possible. (f) Examples In the present invention, a mixed solvent of ethylene glycol and N-ethylformamide is used as the solvent. By the way, the mixing ratio of ethylene glycol and N-ethylformamide is important in order to have little property deterioration even at low temperatures such as -55°C and to obtain stable properties even during load tests at high temperatures such as 105°C. It is. That is, if the N-ethylformamide content is less than 10% by weight, the viscosity increases at low temperatures and there are disadvantages such as lack of electrical conductivity, and if it exceeds 70% by weight,
This has the disadvantage that dry-up due to electrolyte permeation through the sealing material, etc. is accelerated, and the solubility of the solute, which is the electrolyte, is significantly reduced, making it impossible to obtain sufficient electrical conductivity. Therefore, in the present invention, ethylene glycol is
90% by weight, and 70-10% N-ethylformamide
It was expressed as weight%. In the present invention, acetic acid or a salt thereof and adipic acid or a salt thereof are dissolved in the above-mentioned solvent. Hereinafter, the present invention will be explained in more detail with reference to specific examples. Table 1 shows two types of electrolytes (A) and (B) as typical embodiments of the present invention and a conventional electrolyte for comparison.
(C) (D) and reference examples (E) (F) are shown.

【table】

[Table] Table 2 shows the electrolytes (A) to (F) shown in Table 1.
Table 3 shows the results of a temperature characteristic test after prototyping a 50V to 100μF electrolytic capacitor at 105℃.
The results of high-temperature load tests are shown below. The structure of the sample capacitor is a well-known structure, in which a capacitor element is made by winding chemically etched aluminum foil and cathode foil with separator paper in between, impregnated with electrolyte, and then bonded to aluminum using rubber packing. It is stored in a case.

【table】

[Table] As is clear from Tables 2 and 3, when using an electrolyte containing 95ml or more of ethylene glycol,
In other words, in the case of electrolytes (C) and (E), the characteristics at low temperatures are significantly reduced, and when an electrolyte containing 80 ml or more of N-ethylformamide is used, that is, in the case of electrolytes (D) and (F),
When a high temperature load test was performed, characteristic deterioration such as a decrease in capacity and an increase in tan δ occurred. In contrast, when the electrolytic solution of the present invention is used, that is, in the case of electrolytic solutions (A) and (B), stable characteristics can be obtained with little deterioration of characteristics both at low temperatures and during high-temperature load tests. By the way, the amount of ammonium acetate added in the present invention is 5 g, as is clear from Figure 1.
If it is less than 15 g, sufficient electrical conductivity cannot be obtained, and if it is more than 15 g, the electrical conductivity cannot be improved and it becomes difficult to dissolve. Therefore, the amount is preferably 5 g to 15 g. Incidentally, FIG. 1 shows the relationship between the amount of ammonium acetate added and the conductivity in an electrolytic solution consisting of 50 ml of ethylene glycol, 50 ml of N-ethylformamide, and 1 g of ammonium adipate. Furthermore, as is clear from FIG. 2, the amount of ammonium adipate added in the present invention is as follows:
If it is less than 0.5g, sufficient chemical conversion properties cannot be obtained, and 10
If it is more than 0.5g, it will be difficult to dissolve, so 0.5g or more is 10g
The following are preferred. Furthermore, Figure 2 shows the time vs. voltage characteristics depending on the amount of ammonium adipate added in an electrolytic solution consisting of 80 ml of ethylene glycol, 20 ml of N-ethylformamide, and 5 g of ammonium acetate, where (a) the amount added is 0 g, and (b) Addition amount is 0.5g, (c) is addition amount 2g, (d)
indicates the case where the amount added is 10g. Furthermore, although the cases of ammonium acetate and ammonium adipate are shown in FIGS. 1 and 2, it goes without saying that other salts or acetic acid and adipic acid may be used. (G) Effects of the Invention According to the present invention, deterioration of low-temperature characteristics can be prevented without impairing the characteristics during high-temperature load tests.

[Brief explanation of drawings]

1 and 2 are characteristic diagrams of the electrolytic solution according to the present invention, where FIG. 1 is a diagram showing the ammonium acetate addition amount vs. conductivity characteristics, and FIG. 2 is a diagram showing the time vs. voltage characteristics.

Claims (1)

[Claims] 1. Electrolysis characterized by dissolving acetic acid or a salt thereof and adipic acid or a salt thereof in a mixed solvent consisting of 30 to 90% by weight of ethylene glycol and 70 to 10% by weight of N-ethylformamide. Electrolyte for driving capacitors. 2 The amount of acetic acid or its salt added is 100ml of mixed solvent.
The amount of adipic acid or its salt added is 5g or more and 15g or less per 100ml of the mixed solvent.
The electrolytic solution for driving an electrolytic capacitor according to claim 1, characterized in that the electrolytic solution has an amount of 10 g or more and 10 g or less.