JPH0269914A - Electrolyte for electrolytic capacitor - Google Patents

Abstract

PURPOSE:To improve the electric characteristics and reliability of an electrolytic capacitor by incorporating specific compound salt in a predetermined solvent as electrolyte. CONSTITUTION:When an N-alkyl-1-azabicyclo[m,n,p]arcanium compound salt of fatty saturated dicarboxylic acid represented by a formula I is contained in a solvent containing as a main gradient nonproton solvent as electrolyte, it becomes an electrolyte containing the nonproton solvent as a main ingredient and having substantially nonaqueous high conductivity. Accordingly, when this electrolyte is used, its characteristics are stabilized even at the time of use for a long period of time at a high temperature with low loss to enhance its electric characteristics to obtain an electrolytic capacitor having stable characteristics to be maintained for a long period of time with high reliability. In the formula, m: 2 or 3, n: 2 or 3, p: 1, 2 or 3, R1: 10-0C alkenylene group, R2: 6-0C alkyl group, X: hydrogen atom or the same group as N-alkyl-1- azabicyclo[m,n,p]-arcanium group of the formula I.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to an electrolysis method containing an N-alkylazabicycloalkanium compound salt of an aliphatic unsaturated dicarphonic acid as an electrolyte in a solvent mainly consisting of an aprotic solvent. The present invention relates to an electrolytic solution for 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.

As described above, the electrolytic solution for an electrolytic capacitor comes into direct contact with the dielectric layer 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 electrolytic capacitors. For example, if the conductivity of the electrolytic solution is low, the equivalent series resistance inside the electrolytic capacitor increases, resulting in poor high frequency characteristics and loss characteristics.

Based on this background, electrolytes with high conductivity have been selected, and conventionally known electrolytes with high conductivity include organic acids such as adipic acid or their salts dissolved in glycols such as ethylene glycol or alcohols. These are mainly used for normal purposes.

(Problems to be Solved by the Invention) As the range of use of electronic devices has increased in recent years, there has been a growing demand for improvements in the performance of electrolytic capacitors, and the current electrical conductivity of electrolytes is not sufficient. Especially in the case of current electrolytes, when the desired conductivity cannot be obtained or when an electrolyte with low solubility is used, water is intentionally added to improve the conductivity. .

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 electrolyte, 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 improve the electrical characteristics of an electrolytic capacitor by providing a substantially non-aqueous high-conductivity electrolytic solution containing an aprotic solvent as a main component, and to provide stable characteristics. The purpose is to improve the reliability of the electrolytic fundenser by maintaining the same 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 found that an aliphatic unsaturated The present invention was achieved by discovering that N-alkyl-1-azabicycloalkanium compound salts of dicarboxylic acids have high solubility in aprotic solvents, have a high degree of dissociation, and impart high electrical conductivity.

That is, the electrolytic solution for an electrolytic capacitor according to the present invention has the general formula l R21, (where m is 2 or 3, n is 2 or 3, and p is 1 or 2) in a solvent mainly consisting of an aprotic solvent. or 3, R7 is an alkenylene group having 10 or less carbon atoms, R2
is an alkyl group having 6 or less carbon atoms, X is a hydrogen atom or N
N-alkyl-1-azabicyclol'm, n, p] of aliphatic unsaturated dicarboxylic acid of -alkyl-1-azabicyclo [m+ n+ p] represents the same group as the alkanium group)
It is characterized by containing an alkane compound salt as an electrolyte.

The aprotic solvents used include (1) N-methylformamide, N-methylformamide as an amide type;
, N-dimethylformamide, N-ethylformamide, N,N-diethylformamide, N-methylacetamide, N,N-dimethylacetamide, N-ethylacetamide, N,N-diethylacetamide, hexamethylphosphoric amide, (2 ) Dimethyl sulfoxide as an Oquindo type, (3) acetonitrile as a nitrile type, (4) γ-butyrolactone, N-methyl-2-pyrrolidone as an fM-like ester, and an amide type.
Representative examples include ethylene carbonate and propylene carbonate.

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, and the dihydric alcohol compound is ethylene glyfur, and the dihydric alcohol monoalkyl ether compound camethylcell Solv or Ethyl Cell Solv.

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 aliphatic unsaturated dicarboxylic acids that are the object of the present invention include maleic acid, citraconic acid, glutaconic acid, itaconic acid, allylmalonic acid, teraconic acid, fumaric acid, mesaconic acid, or mufonic acid.

Representative examples of ethylkyl-1-azabicycloalkanium compounds are N-alkyl quinuclidinium ethylkyl-azabicyclo[2,2,1]heptanium N-alkyl-1-aza ethylkyl-1
-Azabicyclo[3,2,2]nonanium bicyclo[3,3,II nonanium N-alkyl-1-azabicyclo[3,,2,1]octaniumethylkyl-1-
Azabicycloalkanium compounds are, for example, ■ Prelobe et al.
), Berichte, Vol. 72, p. 1319 (193
9), C^, Grove et al.: Helvety force Chimi force Ethylkyl-1-azabicycloalkane is produced by the tripromide-ammonia method described in Acta Vol. 37, p. 1672 (]954), or by the double alkylation method. The corresponding halogenated N-alkyl-1-azabicycloalkanium compound can be obtained by synthesizing and N-alkylating this with a halogenated alkyl by a conventional method. This is subjected to electrodialysis using an ion exchange membrane to perform anion exchange, dehalogenation, and desalting to obtain an aqueous solution of an N-alkyl-1-azabicycloalkanium hydroxide compound. Equimolar or 172 moles of the desired aliphatic unsaturated dicarboxylic acid were added to the obtained aqueous solution of N-alkyl-1-azabicycloalkanium hydroxide, a neutralization reaction was carried out, and the aliphatic compound was evaporated to dryness under reduced pressure. Mono- or di-N-alkyl-1- of unsaturated dicarboxylic acids
It is possible to obtain an azabicycloalkanium salt.

The electrolytic solution for an electrolytic capacitor according to the present invention is generally prepared by mixing an aprotic solvent with a polyhydric alcohol compound or a monoalkyl ether compound thereof as necessary, and adding a desired N-alkyl- of aliphatic unsaturated dicarboxylic acid. Obtained by adding and dissolving 1-azabicycloalkanium salt.

Kandoto (Example) Hereinafter, regarding an example of the electrolyte solution for an electrolytic capacitor according to the present invention, N-alkyl-1- of aliphatic unsaturated dicarboxylic acid
2 for various aprotic solvents of azabicycloalkanium compound salts or ethylene glycol or methyl cellosolve (ethylene glycol monomethyl ether)
The conductivity of the 0ffiffi% solution is shown in Table 1. In addition,
As a comparative example, a conventional standard electrolyte (ethylene glycol 78% by weight, water 10%, ammonium adipate 12%) was used as a comparative example.
%) is shown.

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 manufactured electrolytic capacitors were made by using aluminum foil as an anode and a cathode, and rolling the foil overlappingly with a separator paper in between to form a cylindrical capacitor element, which was impregnated with the electrolytic solution 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 16V and a rated capacity of 180 μF.

Table 2 shows the initial values of these electrolytic capacitors as well as 110
Capacitance value (μF), tangent of loss angle (tan δ), leakage current (μ
A) (dichotomous value).

Table 2 As is clear from the results of this test, since the electrolytic solution of the present invention has a high conductivity, the loss, i.e., t
The value of anδ becomes low.

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.
In comparing the initial values and the characteristic values after 1000 hours, the properties of the present invention show very little change.

(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 and various electrical devices that are used at high temperatures for long periods of time.

Claims (7)

[Claims] (1) General formulas in solvents that are mainly aprotic solvents: ▲Mathematical formulas, chemical formulas, tables, etc.▼ (In the formula, m is 2 or 3, n is 2 or 3, p is 1, 2 or 3, R_1 is an alkenylene group having 10 or less carbon atoms, R
_2 is an alkyl group having 6 or less carbon atoms, X is a hydrogen atom, or N-alkyl-1-azabicyclo [m
,n,p] of aliphatic unsaturated dicarboxylic acid (representing the same group as the alkanium group)
An electrolytic solution for an electrolytic capacitor containing an alkanium compound salt as an electrolyte. (2) A solvent mainly composed of an aprotic solvent is 100 to 50 parts by weight of an aprotic solvent and 0 to 50 parts by weight of a polyhydric alcohol compound.
The electrolytic solution for an electrolytic capacitor according to claim 1, comprising 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-2-pyrrolidone, ethylene carbonate, propylene carbonate, The electrolytic solution for an electrolytic capacitor according to claim 1 or 2, which is selected from the group of 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) N-alkyl-1-azabicyclo[m,n,p]
Alkanium compounds include N-ethylquinuclidinium, N
The electrolytic solution for an electrolytic capacitor according to claim 1, which is -methylquinuclidium or N-ethyl-1-azabicyclo[3,3,1]nonanium. (7) The electrolytic solution for an electrolytic capacitor according to claim 1, wherein the aliphatic unsaturated dicarboxylic acid is maleic acid, itaconic acid, glutaconic acid, or citraconic acid.