JPH0684704A - Electrolytic solution for driving electrolytic capacitor and electrolytic capacitor using its - Google Patents

Abstract

PURPOSE:To improve the capacitance variation and tandelta variation of an electrolytic capacitor at a high temperature by adding an amino acid containing sulfur to an electrolytic solution composed of a solvent and solute. CONSTITUTION:It is preferable to use amide, lactone, glucol, or a sulfur compound or its carbon salt as the solvent used for the title electrolytic solution. In additions, an inorganic acid, organic acid, or one of their salts can be used for the solute of the solution, but boric acid is preferable among the inorganic acids. Methionine, glutathione, or cystine can be used as an amino acid containing sulfur to be added to the electrolyte and it is preferable to set the adding amount of the amide acid at 0.001-2.0wt.% against the weight of the electrolytic solution. Since the amino acid containing sulfur is more easily adsorbed to a metal than an amino acid containing no sulfur, the amino acid is adsorbed to electrode foil and protects the electrode foil. Therefore, the capacitance variation and tan delta variation of an electrolytic capacitor at a high temperature can be improved, because the electrode foil hardly makes a hydrating reaction, etc.

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 and an electrolytic capacitor using the electrolytic solution.

[0002]

2. Description of the Related Art As a conventional electrolytic capacitor driving electrolytic solution, there is one in which a salt of adipic acid or the like is dissolved in an organic solvent such as ethylene glycol. This electrolyte is usually added with phosphoric acid or phosphorous acid to stabilize its characteristics at high temperatures.

[0003]

In electrolytic capacitors using these electrolytic solutions, the capacitance significantly decreases with time due to the hydration reaction between the water contained in the electrolytic solution and the electrode foil. There is a problem that the demand for high reliability and long life of the capacitor cannot be sufficiently satisfied.

In order to prevent this decrease in electrostatic capacity, for example, Japanese Patent Laid-Open No. 63-7613 discloses glycine and L-.
An electrolytic solution containing aspartic acid, alanine, and glutamic acid is disclosed in JP-A-64-37823 as glycine,
An electrolytic solution containing alanine and valine is disclosed in JP-A-3-91.
No. 225 discloses an electrolytic solution containing glycine and alanine, and JP-A-3-257811 discloses an electrolytic solution containing a silane coupling agent.

However, when these additives are used, a decrease in capacitance can be suppressed, but there is a problem that tan δ change when left for a long time at high temperature cannot be suppressed.

The present invention solves the above problems.
Capacitance change and t of electrolytic capacitor at high temperature
It is an object of the present invention to provide an electrolytic solution for driving an electrolytic capacitor, which can improve an δ change.

[0007]

In order to achieve the above objects, the electrolytic solution for driving an electrolytic capacitor of the present invention is an electrolytic solution comprising a solvent and a solute to which an amino acid containing sulfur is added.

[0008]

The electrolytic solution for driving an electrolytic capacitor having the above-mentioned structure is obtained by adding an amino acid containing sulfur to an electrolytic solution containing a solvent and a solute. An amino acid containing sulfur is more metallic than an amino acid containing no sulfur. Since it is easily adsorbed, the amino acid containing sulfur added to the electrolytic solution composed of the solvent and the solute is adsorbed on the electrode foil to protect the electrode foil,
As a result, the hydration reaction of the electrode foil is less likely to occur, so that it is possible to improve the capacitance change and the tan δ change of the electrolytic capacitor at high temperatures.

[0009]

EXAMPLES Examples of the present invention will be described below.

As the solvent which can be used in the present invention, amides, lactones, glycols, sulfur compounds or carbon salts are preferable, and specific examples thereof include N-methylformamide, γ-butyrolactone and β-butyrolactone. , Γ-valerolactone, N-methylpyrrolidone, ethylene glycol, ethylene glycol monoalkyl ether, ethylene glycol dialkyl ether,
Dimethyl sulfoxide, propylene carbonate, ethylene cyanohydrin and the like can be mentioned, and these solvents can be used alone or in combination of two or more.

As the solute soluble in such a solvent, an inorganic acid, an organic acid or a salt thereof can be used. Among the inorganic acids, boric acid is preferable, and among the organic acids, azelaic acid and adipine are preferable. Acids, benzoic acid, sebacic acid, salicylic acid, phthalic acid, maleic acid and glutaric acid are preferred. And as these salts, ammonium salts, amine salts, quaternary ammonium salts and the like can be used,
The amine salt is preferably methylamine, ethylamine, dimethylamine, diethylamine, trimethylamine, triethylamine, dimethylethylamine, and the quaternary ammonium salt is tetramethylammonium,
Tetraethylammonium, methyltriethylammonium, ethyltrimethylammonium and dimethyldiethylammonium are preferred.

Table 1 shows an example of the composition of the present invention and a conventional electrolytic solution.

[0013]

[Table 1]

(Table 2) prepares electrolytic solutions for driving electrolytic capacitors having the respective compositions shown in (Table 1), and using these electrolytic solutions, a rated voltage of 10 V and a nominal capacitance of 100 μF.
Of the aluminum electrolytic capacitor, and the initial capacitance value (12
0Hz), tan δ (120Hz) and leakage current value, 9
3 shows the rate of change in capacitance, tan δ, and leakage current value when a high temperature load test was performed at 5 ° C. for 500 hours.

[0015]

[Table 2]

As is clear from (Table 2), the conventional examples 2 and 3 are smaller in electrostatic capacitance change than the conventional example 1 and are effective, but are compared with the first, second and third examples of the present invention. And the change in capacitance is large. Further, in the conventional examples 2 and 3, the tan δ change after the high temperature load test with respect to the initial characteristics is large, and the effect of the additive on this tan δ change is not seen, but in Examples 1, 2, 3, 4 of the present invention, t
The change in an δ was much smaller than that of Conventional Examples 1, 2, 3, and 4, and the effect of the additive was observed.

Therefore, each of the embodiments of the present invention can improve the characteristic change of the electrolytic capacitor at high temperature as compared with each of the conventional examples, and in particular, the effect of improving both the capacitance change and the tan δ change. Is large and a highly reliable electrolytic capacitor can be obtained.

The first, second, third, and fourth embodiments of the present invention are described above.
In addition, as is clear from (Table 1), methionine, glutathione, and cystine were added as sulfur-containing amino acids. , Monoaminomonocarboxylic acid such as ergothioneine, carboxymethyl cysteine, cystathionine, cysteic acid, taurine or cysteine is preferable, and the addition amount is 0.001 relative to the weight of the electrolytic solution.
~ 2.0 wt% is preferred. This is 0.001% by weight
If it is not above, the effect is small, while if it exceeds 2.0% by weight, it is difficult to dissolve.

Amino acids include D-form and L-form, but the above-mentioned sulfur-containing amino acids are D-form, L-form, DL-form, and L-L.
Any of body, DD body, and LD body may be used. Among these, L-form and L-L-form are preferable.

[0020]

INDUSTRIAL APPLICABILITY As described above, the electrolytic capacitor driving electrolytic solution of the present invention is obtained by adding a sulfur-containing amino acid to an electrolytic solution containing a solvent and a solute. The sulfur-containing amino acid is a sulfur-free amino acid. Since it is more easily adsorbed on metals, amino acids containing sulfur that are added to the electrolytic solution consisting of solvent and solute are adsorbed on the electrode foil to protect the electrode foil. Is less likely to occur, it is possible to improve the capacitance change and tan δ change of the electrolytic capacitor at high temperature.

Claims (5)

[Claims] 1. An electrolytic solution for driving an electrolytic capacitor, wherein an amino acid containing sulfur is added to an electrolytic solution composed of a solvent and a solute. 2. The electrolytic solution for driving an electrolytic capacitor according to claim 1, wherein the amino acid containing sulfur is monoaminomonocarboxylic acid. 3. A monoaminomonocarboxylic acid is methionine,
Glutathione, cystine, homocysteine, diencholate, lanthionine, ethionine, ergothioneine,
The electrolytic solution for driving an electrolytic capacitor according to claim 2, which is one of carboxymethyl cysteine, cystathionine, cysteic acid, taurine, and cysteine. 4. The amount of methionine, glutathione, cystine, homocysteine, diencholate, lanthionine, ethionine, ergothioneine, carboxymethyl cysteine, cystathionine, cysteic acid, taurine, or cysteine added to the weight of the electrolytic solution, 0.0
The electrolytic solution for driving an electrolytic capacitor according to claim 3, which is from 01 to 2.0% by weight. 5. A driving method comprising an anode electrode and a cathode electrode facing each other with a separator interposed therebetween to form a capacitor element, and adding an amino acid containing sulfur to an electrolyte solution containing a solvent and a solute in the capacitor element. Electrolytic capacitor impregnated with an electrolytic solution.