JPH04230014A - Electrolyte for electrolytic capacitor - Google Patents

Abstract

PURPOSE:To produce the title electrolyte in high solubility of the solute for the solvent used for the electrolyte as well as in high electric conductivity and sparking voltage by a method wherein N-acyl asparagine acid, N-acyl gultamic acid or the salts thereof are used for the solute. CONSTITUTION:As for the acyl radical of N-acyl asparagine acid and N-acyl gultamic acid used for a solute, those in carbon number of 1-10 are applicable but in the concrete, acetyl, alkanoyl radical such as propanoyl, butanoyl, etc., and benzoyl radical can be adduced. Besides, these salts can be used as the solute while as for the salts, amine salt, ammonium salt, the quaternary ammonium salt, quaternary phosphonium salt and the tertiary sulfonium salt can be adduced. Furthermore, the solubility of these salts is recommended to be 1-30wt.% while as for the solvent, N-methyl formaldehyde, etc., are applicable.

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 electrolytic capacitors (hereinafter simply referred to as electrolytic solution). More specifically, the present invention relates to an electrolytic solution using a novel solute consisting of N-acylaspartic acid, N-acylglutamic acid, or a salt thereof.

0002

2. Description of the Related Art The characteristics of electrolytic capacitors are determined by various factors. In particular, the characteristics of the electrolyte that is housed in the outer case together with the capacitor element have a large effect on impedance or equivalent series resistance.

As the electrolytic solution, for example, an ethylene glycol-ammonium adipate solution has been conventionally used.

0004

[Problem to be Solved by the Invention] However, in recent years, as electronic devices have become more sophisticated and their range of applications has expanded, there has been a demand for improved performance of electrolytic capacitors, and conventional electrolytes are insufficient to meet these demands. I have become unable to cope.

[0005] An object of the present invention is to provide an electrolytic solution in which the solubility of the solute in the solvent used in the electrolytic solution is high, and the electrical conductivity and spark voltage are high.

[0006]

[Means for Solving the Problems] In order to achieve the above object, the present inventors conducted intensive studies to find a solute with excellent solubility in a solvent, and found that aspartic acid or glutamic acid The present invention was accomplished by discovering that N-acylated products and their salts have excellent solubility in various solvents used in electrolytic solutions and have excellent properties as solutes in electrolytic solutions.

That is, the present invention provides an electrolytic solution for an electrolytic capacitor, which is characterized in that N-acylaspartic acid, N-acylglutamic acid, or a salt thereof is used as a solute.

The acyl group of N-acylaspartic acid and N-acylglutamic acid used in the present invention generally has 1 to 10 carbon atoms. Specific examples include alkanoyl groups such as acetyl, propanoyl, butanoyl; and benzoyl groups.

These N-acylaspartic acids and N
Both -acylglutamic acids are used as solutes in electrolytes, and salts of these acids can also be used in the same way. Examples of the salt include amine salts, ammonium salts, quaternary ammonium salts, quaternary phosphonium salts, and tertiary sulfonium salts.

In the present invention, N-methylformamide, N-ethylformamide, N,N-dimethylformamide is used as a solvent for dissolving N-acylaspartic acid, N-acylglutamic acid, or a salt thereof to form an electrolytic solution. , N,N-diethylformamide, N-methylacetamide, N,N-dimethylacetamide, N-methylpyrrolidinone and other amide solvents; γ-butyrolactone, γ-parerolactone, δ-parerolactone and other lactone solvents; ethylene carbonate, propylene carbonate , carbonate solvents such as butylene carbonate; alcohol solvents such as ethylene glycol, glycerin, and ethylene glycol monomethyl ether; nitrile solvents such as 3-methoxypropionitrile and glutaronitrile; or phosphate ester solvents such as trimethyl phosphate and triethyl phosphate. , can be used alone or in the form of a complex solvent.

The amount of the solute dissolved in the solvent varies depending on the electrical conductivity and spark voltage of the intended electrolyte, but is generally below the saturation concentration, preferably 1 to 1.
It is 30% by weight.

The electrolytic solution of the present invention essentially consists of N-acylaspartic acid, N-acylglutamic acid, or a salt thereof and a solvent, and has the following properties: prevention of electrolytic corrosion, reduction of leakage current, absorption of hydrogen gas, and oxidation. Various co-solutes, such as phosphoric acid derivatives and nitritebenzene derivatives, can be added for the purpose of improving the stability of the aluminum film.

[0013]

[Effects of the Invention] N-acylaspartic acid, N-acylglutamic acid, and their salts used as solutes in the present invention have good solubility in solvents, and their electrolytes exhibit high electrical conductivity. In addition, by dissolving it in a solvent that maintains its liquid state over a wide temperature range, it is possible to obtain an electrolytic solution that can be used over a wide temperature range. Therefore, the electrolytic solution of the present invention is suitable as an electrolytic solution for electrolytic capacitors.

[0014]

[Examples] The present invention will be explained in more detail with reference to Examples and Comparative Examples below.

Example 1 Using ethylene glycol as a solvent, 10% by weight of ammonium N-acetylaspartate was dissolved in it to obtain a uniform electrolytic solution. 25 of this electrolyte
The electrical conductivity at ℃ was 1.5 mS/cm2, and the spark voltage was 210V when a constant current of 10 mA/cm2 was applied to the aluminum electrode.

Comparative Example 1 In Example 1, ammonium aspartate of the same concentration was used instead of ammonium N-acetylaspartate, but it did not dissolve completely and was unsuitable for use as an electrolyte. Ta.

Example 2 Using γ-butyrolactone as a solvent, 20% by weight of tetraethylammonium N-acetylglutamate was dissolved in it to obtain a uniform electrolyte solution. The electrical conductivity of this electrolyte at 25°C and the spark voltage measured in the same manner as in Example 1 were 4.1 mS/cm, respectively.
, 180V.

Comparative Example 2 In Example 2, tetraethylammonium glutamate of the same concentration was used instead of tetraethylammonium N-acetylglutamate, but it did not dissolve completely and was unsuitable for use as an electrolyte. Ta.

Example 3 Using the same solvent and solute as in Example 2, the solute concentration was reduced to 1.
．． Four types of electrolytic solutions were prepared by changing the amount in the range of 25 to 10% by weight. Their electrical conductivity and spark voltage were measured and their changes observed. The results were as shown in Figure 1.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the relationship between electrical conductivity and spark voltage at various solute concentrations in Example 3.

[Explanation of symbols]

The numbers in the figure indicate the solute concentration in weight percent.

Claims (1)

[Claims] 1. An electrolytic solution for an electrolytic capacitor, characterized in that N-acylaspartic acid, N-acylglutamic acid, or a salt thereof is used as a solute.