JPH0254918A - Electrolytic solution for electrolytic capacitor - Google Patents

Abstract

PURPOSE:To obtain a capacitor with low loss which can be used for a long time under high temperatures by using an electrolytic solution which is made by mixing as an electrolyte specific monospiro ammonium compound salt or dispiro ammonium compound salt into a solvent consisting of a specific solvent. CONSTITUTION:Monospiro ammonium compound salt or dispiro ammonium compound salt of an alicyclic monocarboxylic oxide or dicarboxylic oxide expressed by a formula I is mixed as an electrolyte into a solvent consisting of a non-protic solvent to make a nonaqueous high-conductivity electrolytic solution consisting of a non-protic solvent. By using this electrolytic solution, such an electrolytic capacitor that has high electric characteristics and has stable ones even when used for a long time at high temperatures. (In the formula, (n) is an integer from 4 to 8, (m) is integer from 3 to 6, R is an alicyclic group containing 3 to 10 carbon atoms and X is a hydrogen atom or a carboxylic group or a base of the carboxylic group and the same group as a spiro ammonium group in the formula.).

Description

Detailed Description of the Invention (Industrial Application Field) The present invention is directed to an electrolyte containing a salt of a mono- or di-spiroammonium compound of an alicyclic mono- or dicarboxylic acid compound in a solvent mainly consisting of an aprotic solvent. This invention relates to an electrolytic solution for electrolytic capacitors.

(Prior art) An electrolytic capacitor uses a valve metal such as aluminum or tantalum on the surface of which an insulating oxide film is formed as an anode electrode, the oxide film layer is used as a dielectric, and the surface of the oxide film layer is It is constructed by bringing an electrolytic solution, which forms an electrolyte layer, into contact with it, and further arranging a current collecting electrode, usually called a cathode.

The electrolyte for an electrolytic capacitor comes into direct contact with the dielectric layer, as described above, and acts as a true cathode. That is, the electrolytic solution is interposed between the dielectric layer and the current collecting cathode of the electrolytic capacitor, and the resistance of the electrolytic solution is inserted in series with the electrolytic capacitor. Therefore, its characteristics become a major factor that influences the characteristics of the electrolytic capacitor. For example, if the electrolytic solution has a low amount of conductive dust, it increases the equivalent series resistance inside the electrolytic capacitor, resulting in poor high frequency characteristics and loss characteristics. From this background, electrolytes with high conductive dust have been selected, and as electrolytes with high conductive dust,
Organic acids such as adipic acid or their salts dissolved in glycols such as ethylene glycol or alcohols are mainly used for ordinary purposes.

(Problems to be Solved by the Invention) Due to the recent increase in the scope of use of electronic devices, there has been an increasing demand for improvements in the performance of electrolytic capacitors, and the current conductive dust in electrolytes is not sufficient. Especially in the case of current electrolytes, when the desired conductive dust cannot be obtained or when an electrolyte with low solubility is used, water is intentionally added to improve the conductive dust. .

However, in recent years, when electrolytic capacitors are used for long periods of time at higher temperatures than conventional products, the presence of moisture in the electrolyte can cause deterioration of the dielectric film layer and internal steam of the electrolytic capacitor. This increases the pressure, leading to damage to the sealing part and evaporation of the electric angle liquid, which shortens its lifespan, and has the disadvantage that stable characteristics cannot be maintained over a long period of time.

Therefore, an object of the present invention is to provide a substantially non-aqueous high-conductivity electrolytic solution containing an aprotic solvent as a main ingredient, thereby making the electrical characteristics of an electrolytic capacitor the same and stable. The purpose is to improve the reliability of electrolytic capacitors by maintaining them for a long period of time.

(Means for Solving the Problems) As a result of extensive research into an electrolyte that is a substantially non-aqueous electrolyte mainly composed of an aprotic solvent and provides high conductivity, the present inventors have discovered that an alicyclic monomer Alternatively, the present invention was achieved by discovering that a salt of a dicarboxylic acid compound with a mono- or dispiroammonium compound has high solubility in an aprotic solvent, has a high degree of dissociation, and imparts high electrical conductivity.

That is, the electrolytic solution for an electrolytic capacitor according to the present invention contains a compound having the general formula: (where n is an integer of 4 to 8, m is an integer of 3 to 6, and R is a carbon atom 3 to 10 alicyclic groups, X represents a hydrogen atom or a carboxyl group, or a base of this carboxyl group and the same group as the spiroammonium group shown in the formula) - or di-spiroammonium compound salt as an electrolyte.

Solvents mainly composed of aprotic solvents are aprotic solvents 10
It consists of 0 to 50 parts by weight and 0 to 50 parts by weight of a polyhydric alcohol compound.

The aprotic solvents used include (+) amide type N-methylformamide, N,N-dimethylformamide, ethylformamide, N,N-diethylformamide, N-methylacetamide, N,N-methyl Acetamide, N-ethylacetamide, N,N-diethylacetamide, hexamethylphosphoric amide (2) Oxide-based dimethylphorfoquine (3) Nitrile-based acetonitrile (4) Cyclic ester, amide-based γ-butyrolactone, N-methyl- Representative examples include, but are not limited to, 2-pyrrolidone, ethylene carbonate, propylene carbonate, and the like.

The polyhydric alcohol compound that is the object of the present invention is preferably a dihydric alcohol compound or a monoalkyl ether of a dihydric alcohol compound, the dihydric alcohol compound is ethylene glycol, and the dihydric alcohol monoalkyl ether compound is methyl cellosolve. Or ethyl cellosolve.

The weight ratio of the polyhydric alcohol compound to the aprotic solvent is (100-50): (0-50),
Although 100% aprotic solvent is suitable, up to about 50% polyhydric alcohol compound may be used as appropriate without substantially avoiding product deterioration.

The alicyclic mono- or dicarboxylic acid compounds to which the present invention is applied include cyclopropanecarboxylic acid, cyclopropane, l-dicarboxylic acid, cyclobutanecarboxylic acid, cyclobutanecarboxylic acid,
1,1-dicarboxylic acid, cyclobencunecarboxylic acid, cyclopentanedicarboxylic acid, hexahydrobenzoic acid, hexahydrophthalic acid, hexahydroisophthalic acid, hexahydroterephthalic acid, 3,4,5.6-titrahydrophthalic acid, 1.2,3.4-tetrahydroterephthalic acid, camphoric acid, incamphoric acid, 5-huncholic acid,
These include cyclooctatetraenecarboxylic acid, cyclohebutanecarboxylic acid, and cyclohebutanedicarboxylic acid.

Spiroammonium acid compounds are! , 1°−spibilo[
Azetidine 1,1°-biviperidinium]spiroammonium compound J, Y. Brown, Berichna. 49th
For example, 1,1-spirobipyrrolidinium bromide can be obtained by reacting pyrrolidine with 1,4 dibromobutane.

An aqueous solution of 1,1-spirobipyrrolidinium hydroxide can be synthesized by electrodialyzing the obtained 1.1'-subiropipyrrolidinium bromide using an ion exchange membrane to perform anion exchange.

A desired alicyclic mono- or dicarboxylic acid compound is added to the obtained aqueous solution of 1.1'-spirobipyrrolidinium hydroxide, a neutralization reaction is carried out, and water is removed by drying under reduced pressure. A 1,1°-spirobipyrrolidinium salt of a dicarboxylic acid compound can be obtained.

The electrolytic solution for an electrolytic capacitor according to the present invention includes: - a spirocarbon of a desired alicyclic mono- or dicarboxylic acid compound in a solvent prepared by mixing an aprotic solvent with a polyhydric alcohol compound or its monoalkyl ether compound as required; It is obtained by adding and dissolving one or two equivalents of ammonium compound salt.

(Example) Hereinafter, various aprotic solvents of spiroammonium compound salts of various aliphatic saturated dicarboxylic acid compounds or combination thereof with ethylene glycol or methyl cellosolve (ethylene glycol The electrical conductivity of the 15.20% by weight solution relative to monomethyl ether) is shown in Table 1. As a comparative example, a conventional standard electrolyte solution (78% by weight of ethylene glycol, 10% by weight of water) was used as a comparative example.
%, ammonium adipate 12%).

As can be seen from the above results, the electrolytic solution of the present invention exhibits higher conductivity than the conventional electrolytic solution.

Next, electrolytic capacitors were manufactured using the electrolytes of Examples 1 to 10 and Comparative Example, and their characteristics were compared.

The produced electrolytic capacitors were made by using aluminum foil as an anode and a cathode, and rolling the foil overlappingly with separator paper in between to form a cylindrical capacitor element, which was impregnated with the electrolyte of each example and comparative example. It is stored in an external case and sealed.

Both use the same capacitor element, and have a rated voltage of 16 and a rated capacity of 180 μF.

Table 2 shows the initial values of these electrolytic capacitors and 85℃
Capacitance value (μF), tangent of loss angle (tan δ), and leakage current (μ^) after 1000 hours have passed after applying the rated voltage at
(dichotomous value).

In addition, since it essentially does not contain water, there is no appearance abnormality or decrease in capacitance due to increased internal pressure even when placed under high temperature loads.
Even when comparing the initial values and the characteristic values after 1000 hours, there is very little change in the properties of the present invention.

(Effects of the Invention) The electrolytic capacitor using the electrolyte according to the present invention has a low loss value and can maintain stable characteristics even when used at high temperatures for long periods of time, so it can be used at high frequencies and requires high efficiency. It can be used in power supply devices such as switching regulators, which are used for a long period of time, and various electrical devices that are used at high temperatures for long periods of time.

Patent Applicant: Nippon Chemi-Con Co., Ltd. As is clear from the results of this test, the electrolytic solution of the present invention has a high conductivity, so the loss, that is, the value of tan δ, is lower than that of the conventional electrolyte.

Claims (7)

[Claims] (1) General formulas in solvents that are mainly aprotic solvents: ▲Mathematical formulas, chemical formulas, tables, etc.▼ (In the formula, n is an integer from 4 to 8, m is an integer from 3 to 6, and R is a carbon atom. 3 to 10 alicyclic groups, X represents a hydrogen atom or a carboxyl group, or a base of this carboxyl group and the same group as the spiroammonium group shown in the formula) An electrolytic solution for an electrolytic capacitor containing - or di-spiroammonium compound salt as an electrolyte. (2) The solvent mainly composed of an aprotic solvent contains 100 to 50 parts by weight of an aprotic solvent and 0 to 5 parts by weight of a polyhydric alcohol compound.
The electrolytic solution for an electrolytic capacitor according to claim 1, comprising 0 parts by weight. (3) The aprotic solvent is N-methylformamide, N
, N-dimethylformamide, N-ethylformamide, N,N-diethylformamide, N-methylacetamide, N,N-dimethylacetamide, N-ethylacetamide, N,N-diethylacetamide, γ-butyrolactone, N-methyl- The electrolytic solution for an electrolytic capacitor according to claim 1 or 2, which is selected from the group of 2-pyrrolidone, ethylene carbonate, propylene carbonate, dimethyl sulfoxide, acetonitrile, or a mixture thereof. (4) The electrolytic solution for an electrolytic capacitor according to claim 2, wherein the polyhydric alcohol compound is a dihydric alcohol compound or a monoalkyl ether of a dihydric alcohol compound. (5) The electrolytic solution for an electrolytic capacitor according to claim 2, wherein the dihydric alcohol compound is ethylene glycol and the dihydric alcohol monoalkyl ether compound is methyl cellosolve or ethyl cellosolve. (6) Alicyclic mono- or dicarboxylic acid compounds include cyclopropane-1,1-dicarboxylic acid, cyclobutane-1,1
2. The electrolytic solution for an electrolytic capacitor according to claim 1, which is a -dicarboxylic acid, hexahydrophthalic acid, or hexahydrobenzoic acid. (7) The spiroammonium compound is 1,1'-spirobipyrrolidinium, spiro[piperidine-1,1'-pyrrolidinium], 1,1'-spirobipiperidinium or 1,1'-spirobipyrrolidinium. 2. The electrolytic solution for an electrolytic capacitor according to claim 1, wherein the electrolytic solution is Ni.