JPH04311020A - Electrolyte for driving electrolytic capacitor - Google Patents

Abstract

PURPOSE:To make it possible to use the title electrolyte in a wide range of voltage by growing a few-defect oxide film, by increasing spark-generating voltage by dispersing an ultrafine particle inorganic compound into an electrolyte. CONSTITUTION:Alcohols and the like are used for the electrolyte with which a superfine particle inorganic compound is dispersed. Inorganic acid, organic acid or its salt, and borasic acid, azelaic acid and the like are used for the solute. Ammonium salt and the like are used for the salt of acid. The quantity of the superfine particle inorganic compound to be dispersed should be 0.1 to 30wt.% for the electrolyte. The diameter of particles should be 100nm or smaller. The superfine particle inorganic compound is turned into a coroidal form by electrostatical charging on the electrolyte, and it is dispersed in the electrolyte uniformly. When an oxide film is grown, the superfine particle inorganic compound is absorbed and flocculated, and the defects of the oxide film are filled up. As a result, an oxide film having few defects can be formed, and spark generating voltage can be increased.

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 more specifically, to an electrolytic solution for driving an aluminum electrolytic capacitor.

0002

BACKGROUND OF THE INVENTION Conventional electrolytic solutions for driving aluminum electrolytic capacitors have been prepared by dissolving boric acid or ammonium borate as an electrolyte in ethylene glycol because the spark generation voltage can be made relatively high.

However, in such an electrolytic solution, a large amount of water is generated in the electrolytic solution due to crystallization water directly released from boric acid and condensed water generated by the esterification reaction between ethylene glycol and boric acid. 100
If this electrolyte is used in an aluminum electrolytic capacitor with a temperature exceeding ℃, the water in the electrolyte will evaporate into water vapor, which will increase the internal pressure inside the aluminum electrolytic capacitor's package and cause it to break down. was there. In order to solve these problems, organic carboxylic acids such as adipic acid or benzoic acid or their salts, which have a very slow esterification reaction with ethylene glycol, were considered as electrolytes, but in this case, the necessary The drawback is that it is not possible to obtain a high spark generation voltage. In order to solve this drawback, there is an example in which polyoxyethylene dicarboxylic acid is added to the electrolytic solution to improve the spark generation voltage (Japanese Patent Application Laid-open No. 176218/1983).

[0004] Furthermore, Japanese Patent Application Laid-Open No. 12717/1983 discloses a method in which ceramic powder is contained in an electrolytic solution.

Furthermore, as an example of a metal oxide contained in an electrolyte, there is an example of bismuth oxide (Japanese Patent Publication No. 2-57).
(See Publication No. 328).

[0006]

[Problems to be Solved by the Invention] However, polyoxyethylene dicarboxylic acid, which is an additive for improving the spark generation voltage, has the disadvantage of lowering the specific conductivity and increasing the loss of electrolytic capacitors. be. In addition, the size of the ceramic powder is 5 μm to 50 μm.
is known, but this is difficult to disperse,
Moreover, the effect on the spark generation voltage is also not clear. Furthermore, the bismuth oxide known from Japanese Patent Publication No. 2-57328 has the disadvantage that it is difficult to disperse and readily precipitates, and its effect on improving the spark generation voltage has not been clarified.

The present invention solves the above-mentioned conventional problems, and aims to provide an electrolytic solution for driving an electrolytic capacitor that has a high spark generation voltage without reducing specific conductivity.

[0008]

[Means for Solving the Problems] In order to solve the above problems, the present invention is characterized in that an ultrafine inorganic compound is dispersed in an electrolytic solution.

[0009]

[Function] The electrolytic solution for driving an electrolytic capacitor of the present invention described above has an ultrafine particle inorganic compound dispersed therein, and since this ultrafine particle inorganic compound is charged in the electrolytic solution and becomes colloidal, It can be uniformly dispersed in the electrolyte. In addition, when an oxide film is formed, the ultrafine inorganic compounds are adsorbed and aggregated to fill in the defective parts of the oxide film, making it possible to produce an oxide film with fewer defects, thereby increasing the spark generation voltage. be.

0010

[Examples] Examples of the present invention will be described below.

The electrolytic solution for driving an electrolytic capacitor of the present invention is basically characterized by dispersing an ultrafine inorganic compound, and the ultrafine inorganic compound includes metal oxides, metal oxides,
Metal nitrides or metal carbides are preferred. Usually, ultrafine particles are electrically charged in an electrolytic solution, so they become colloidal and disperse, but some particles are difficult to disperse depending on the pH of the solution and the type of inorganic compound. In that case, dispersion can be achieved by using an appropriate surfactant or performing surface treatment.

Examples of metal oxides include basic oxides (TiO2, ZrO2, Fe2O3, HfO2, Y2
O3, Al2O3, Ga2O3, In2O3, SnO2
, Bi2O3, etc.), acidic oxides (Nb2O5, Ta2O
5, WO3, GeO2, SeO2, Sb2O3, TeO
2 etc.), composite oxides (SiO2-Al2O3, SiO2
-MgO, SiO2-CaO, SiO2-SrO, Si
O2-BaO, SiO2-ZrO2, etc.). Among these, TiO2 is preferred.

Examples of metal nitrides include TiN, S
i3N2, AlN, TaN, Zr3N4, NbN, Zr
An example is N. Among these, preferred is Ti
It is one type or a mixture of two or more types of N, Si3N2, AlN, and Zr3N4.

[0014] As the metal carbide, SiC, TiC, M
Examples include o2C and WC. Among these, preferred is one type or a mixture of two types of SiC and TiC.

Further, examples of solvents that can be used in the electrolytic solution in which the ultrafine inorganic compound is dispersed include alcohols {1
Alcohols (methyl alcohol, ethyl alcohol,
propyl alcohol, butyl alcohol, diacetone alcohol, benzyl alcohol, amino alcohol, etc.)
, dihydric alcohols (ethylene glycol, propylene glycol, diethylene glycol, hexylene glycol, etc.), trihydric alcohols (glycerin, etc.), hexitol, etc.}, ethers {monoethers (ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol monomethyl) ether,
diethylene glycol monoethyl ether, ethylene glycol phenyl ether, etc.), diethers (ethylene glycol dimel ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, etc.)}, amides {formamides (N-methylformamide, N,N-dimethylformamide, N-ethyl Formamide, N,N-diethylformamide, etc.), acetamides (N-methylacetamide, N,N-dimethylacetamide, N-ethylacetamide, N,N-diethylacetamide, etc.), propionamides (N,N-diethylacetamide, etc.)
-dimethylpropionamide, etc.), hexamethylphosphorylamide, etc.}, oxazolidinones (N-methyl-2
-oxazolidinone, 3,5-dimethyl-2-oxazolidinone, etc.), lactones (γ-butyrolactone, α-acetyl-γ-butyrolactone, β-butyron lactone,
γ-valerolactone, δ-valerolactone, etc.), nitriles (acetonitrile, acrylonitrile, etc.), dimethyl sulfoxide, sulfolane, 1,3-dimethyl-2-
Examples include imidazolidinone, N-methylpyrrolidone, aromatic solvents (toluene, xylene, etc.), paraffinic solvents (normal paraffin, isoparaffin, etc.), and mixtures of two or more of these. Among these, preferred are γ-butyrolactone or ethylene glycol-based solvents.

[0016] The solute is an inorganic acid, an organic acid, or a salt thereof, such as boric acid, azelaic acid, adipic acid, glutaric acid, phthalic acid, maleic acid, benzoic acid, or a salt thereof. .

[0017] As the above acid salts, ammonium salts, amine salts, quaternary ammonium salts, etc. can be used.

[0018] The amount of the ultrafine inorganic compound to be dispersed is 0.1 to 30 wt%, preferably 1 to 20 wt%, based on the electrolytic solution. This is because they have no effect at 0.1 wt% or less, and tend to aggregate at 30 wt% or more.

[0019] Also, the smaller the particle size, the better;
Although it can be dispersed from about μm, in this case, it is preferable that it is 100 nm or less.

Next, specific embodiments of the present invention will be explained. (Table 1) shows conventional examples 1, 2, and 3 and embodiment 1 of the present invention.
, 2, 3, 4, and 5, as well as the measurement results of specific conductivity at 30° C. and spark generation voltage in each of these examples.

Titanium oxide, which is a metal oxide constituting the ultrafine inorganic compound used in Examples 1 and 5 of the present invention, was obtained by oxidizing titanium tetrachloride vapor in the gas phase with oxygen. It was mechanically stirred and dispersed in the electrolyte.

[0022]

[Table 1]

As is clear from this (Table 1), Examples 1 and 5 of the present invention in which titanium oxide, which is a metal oxide constituting an ultrafine particle inorganic compound, is dispersed, and the metal oxide constituting an ultrafine particle inorganic compound. The electrolytes of Examples 2 and 3 of the present invention in which titanium nitride and tantalum nitride, which are nitrides, are dispersed, and Example 4 of the present invention, in which silicon carbide, which is a metal carbide constituting an ultrafine particle inorganic compound, are dispersed are as follows: Compared to the electrolytic solutions of Conventional Examples 1, 2, and 3, the spark generation voltage can be increased without reducing the specific conductivity.

(Table 2) shows the conventional examples 1 and 2 shown in (Table 1).
, 3, and the test results of various characteristics of electrolytic capacitors using electrolytic solutions in Examples 1, 2, 3, 4, and 5 of the present invention. The ratings of these electrolytic capacitors are 40 for Examples 1, 2, 3, and 4 of the present invention and conventional examples 1 and 2.
0V is 1500μF, and Example 5 of the present invention and Conventional Example 3 are 100V and 47μF.

[0025] Note that aging is performed in Example 1 of the present invention,
In Examples 2, 3, and 4 and Conventional Examples 1 and 2, a voltage of 450V was applied, and in Example 5 of the present invention and Conventional Example 3, a voltage of 120V was applied. In this case, all of the conventional examples 1 and 3 were short-circuited when voltage was applied.

[0026]

[Table 2]

As is clear from this (Table 2), the electrolytic capacitors using the electrolyte in each example of the present invention can lower tan δ compared to the conventional example, and can be used in a wide voltage range. It is something that can be done.

[0028]

[Effects of the Invention] As described above, the electrolytic solution for driving an electrolytic capacitor of the present invention has an ultrafine particle inorganic compound dispersed therein. Therefore, it can be uniformly dispersed in the electrolyte. In addition, when an oxide film is formed, the ultrafine inorganic compounds are adsorbed and aggregated to fill in the defective parts of the oxide film, making it possible to produce an oxide film with fewer defects.This also makes it possible to increase the spark generation voltage. An electrolytic capacitor using an electrolytic solution can have a low tan δ and can be used in a wide voltage range.

Claims (8)

[Claims] 1. An electrolytic solution for driving an electrolytic capacitor, characterized in that an ultrafine inorganic compound is dispersed therein. 2. The electrolytic solution for driving an electrolytic capacitor according to claim 1, wherein the ultrafine inorganic compound is a metal oxide. 3. The electrolytic solution for driving an electrolytic capacitor according to claim 1, wherein the ultrafine inorganic compound is a metal nitride. 4. The electrolytic solution for driving an electrolytic capacitor according to claim 1, wherein the ultrafine inorganic compound is a metal carbide. 5. The electrolytic solution for driving an electrolytic capacitor according to claim 2, wherein the metal oxide is TiO2. [Claim 6] The metal nitride is TiN, Si3N2, AlN.
4. The electrolytic solution for driving an electrolytic capacitor according to claim 3, which is one type or a mixture of two or more types selected from , TaN, and Zr3N4. 7. The electrolytic solution for driving an electrolytic capacitor according to claim 4, wherein the metal carbide is SiC and TiC alone or in a mixture. Claim 8: The size of the ultrafine inorganic compound is 100 nm.
The electrolytic solution for driving an electrolytic capacitor according to claim 1, which is as follows.