JPH0269913A - 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 alkylene 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 l.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of application in production) The present invention is directed to the use of an N-alkyl-l azabicycloalkanium compound salt of an aliphatic saturated dicarboxylic acid as an electrolyte in a solvent mainly consisting of an aprotic solvent. The present invention relates to an electrolytic solution for electrolytic capacitors.

(Prior art) An electrolytic capacitor uses a valve metal such as aluminum or tanker metal with an insulating oxide film formed on its surface as an anode electrode, and uses the oxide film layer as a dielectric material. It is constructed by bringing an electrolytic solution, which forms an electrolyte layer, into contact with the electrode, 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 internal equivalent series resistance of the electrolytic fluid increases, which has the disadvantage of worsening high frequency characteristics and loss characteristics.

Against this background, electrolytes with high conductivity are also being sought, and as conventionally known electrolytes with high conductivity, a-organic acids such as ampic acid or their salts are mixed with glycols such as ethylene glycol or alcohols. The dissolved form is mainly used for normal purposes.

(Problems to be Solved by the Invention) Due to the recent increase in the scope of use of electronic devices, there has been a growing demand for improvements in the performance of electrolytic capacitors, and the current conductivity of electrolytic solutions cannot be said to be sufficient. Particularly in the case of current electrolytes, if the desired conductivity cannot be obtained, or if an electrolyte with low solubility is used, it is necessary to intentionally add water to improve the conductivity. It is being said.

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 the electrolytic capacitor. This increases the internal vapor 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, it is an object of the present invention to provide a substantially non-aqueous high conductivity electrolyte containing a non-pro-I-prone solvent, thereby improving the electrical properties of electrolytic capacitors and stabilizing them. The objective is to improve the reliability of electrolytic capacitors by maintaining their characteristics over a long period of time.

(Another Means to Solve the Problem) 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 discovered that an aliphatic saturated dicarboxylic acid The present invention was achieved by discovering that the acid N-alkyl-1-azavinicloalkanium compound salt has high solubility in aprotic solvents, has a high degree of dissociation, and imparts high conductivity.

That is, the electrolytic solution for an electrolytic condenser according to the present invention has a general formula (where m is 2 or 3, n is 2 or 3, p is 1.2 or 3, R1 is an alkylene group having 10 or less carbon atoms, R9 is an alkyl group having 6 or less carbon atoms, and X is a hydrogen atom or ethylkyl-1-azabicyclo [m, n,
ethylkyl-1-azabicyclo[m, n,
p] It is characterized by containing an alkanium 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 oxide type, (3) acetonitrile as a nitrile type, (4) γ- as a cyclic ester and amide type.
Representative examples include butyrolactone, N-methyl-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, 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 saturated dicarboxylic acid compounds targeted by the present invention include malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, corkic acid, azelaic acid, sebacic acid, undecanoic acid, dobucanic acid, brassic acid, tetradecanoic acid,
These include bentadecanniic acid, tabucic acid, hebutadecanniic acid, octadecanoic acid, nonadecanniic acid, icosanniic acid, heneicosanniic acid, docosanniic acid, and the like.

Representative examples of N-alkyl-1-azabicycloalkanium compounds are: N-alkyl quinuclidinium N-alkyl azabicyclo[2,2,1]N-alkyl-1-azaN-alkyl-I-aza N-alkyl-1-azabicyclo[3,2,l]octanium k" N-alkyl-1-azabicycloalkanium compounds are, for example, etc., Berichte Volume 72,
No. 1319 page (1,939), CA, Grove et al.: Helvetica Chimi Power Acta Vol. 37, No. 1672 page (+9
54) etc., or the tripromide-ammonia method described in 2.
Ethylkyl-1-azabicycloalkane is synthesized by double alkylation method, etc., and this is N-alkylated with a halogenated alkyl by a conventional method to obtain the corresponding halogenated N-alkyl-1
-Azabicycloalkanium compounds can be obtained. This is subjected to electrodialysis using an ion exchange membrane to perform dehalogenation and desalting to perform anion exchange to obtain an aqueous solution of an N-alkyl-1-azabicycloalkanium hydroxide compound. Equimole or 1/2 mole of the desired aliphatic saturated dicarboxylic acid is added to the obtained aqueous solution of N-alkyl-1-azabicycloalkanium compound, a neutralization reaction is carried out, and the aliphatic saturated dicarboxylic acid is evaporated to dryness under reduced pressure. Mono- or di-N-alkyl-1-azabicycloalkanium salts of dicarboxylic acids can be obtained.

The electrolytic solution for electrolytic contin → no according to the present invention generally includes:
It is obtained by adding and dissolving the desired N-alkyl azavinchloroalkanium salt of an aliphatic saturated dicarboxylic acid in a solvent prepared by mixing an aprotic solvent with a polyhydric alcohol compound or its monoalkyl ether compound as required.

Example (Example) The following is an example of the electrolytic solution for electrolytic condensation according to the present invention.
Table 1 shows the conductivities of 20 weight It% solutions of the Asapin Chloalkalinium compound salt in various aprotic solvents or with ethylene glycol or methyl cellosolve (ethylene glycol monomethyl ether). As a comparative example, a conventional standard electrolyte (ethylene glycol 7B
'@71%, water' 0%, ammonium ambate 12%
) 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 (a).

Next, electrolytic contin fields were produced using the electrolytes of Examples 1 to 10 and Comparative Example, and their properties were compared.

The manufactured electrolytic capacitor was made by using aluminum foil as an anode and a cathode, and rolling it overlappingly with separator paper in between to form a cylindrical element.The electrolyte solution of each example and comparative example was It is impregnated with water, stored in an outer case, and sealed.

Both use the same condenser element, and have a rated voltage of 16V and a rated capacity fd18 (lμF).

Table 2 shows the initial values of these electrolytic capacitors]]0
Capacitance value (μF), tangent of loss angle (tan δ), leakage current (μ
8) (dichotomous value).

As is clear from the results of this test, since the electrolytic solution of the present invention has a high conductivity, the loss, that is, t, is lower than that of the conventional one.
The value of an δ becomes low.

In addition, since the wood does not contain water, even if it is placed under high temperature load, there will be no appearance abnormality or a decrease in electrostatic capacity due to an increase in internal pressure.
In comparing the initial values and the characteristic values after 1000 hours, the changes in the properties of the present invention are extremely small.

(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 is highly efficient. 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.

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 alkylene 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 saturated dicarboxylic acids (representing the same group as the alkanium group)
, n, p] 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 saturated dicarboxylic acid compound is succinic acid, glutaric acid, adipic acid, or corkic acid.