JPH0269919A - 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 alicyclic mono- or di-oarboxylate compound 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, n: 2 or 3, p: 1, 2 or 3, R1: 3-10C alicyclic group, X: hydrogen atom or carboxyl group or basic group of the same group as the N-alkyl-1-lazabicyclo-[m,n,p]arcanium group in the formula I, and R2: 8-0C alkyl group.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention provides an electrolytic solution in which an N-alkyl 1-azavinicloalkanium compound salt of an alicyclic mono- or dicarboxylic acid is dissolved in a solvent mainly consisting of an aprotic solvent. The present invention relates to an electrolytic solution for electrolytic capacitors containing as follows.

(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 of the electrolytic capacitor and the collector cathode, 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.

Against this background, electrolytes with high conductivity are also being sought, 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. Particularly 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 JRJ mouth part and deterioration of life due to evaporation of the electrolyte, 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 electrolytic capacitors and to maintain stable characteristics for a long time by providing a substantially non-aqueous highly conductive electrolytic solution containing an aprotic solvent as a main component. To improve the reliability of electrolytic capacitors by maintaining them for a 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 The present invention was achieved by discovering that N-alkyl-1 azabicycloalurium compound salts of dicarboxylic acid compounds have high solubility in aprotic solvents, have a high degree of dissociation, and impart high conductivity. .

That is, the electrolytic solution for an electrolytic capacitor 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, R , is an alicyclic group having 3 to 10 carbon atoms; X is a hydrogen atom or a carboxyl group; N-alkyl-1-azabicyclo[m, n, p] of an alicyclic mono- or dicarboxylic acid compound of a base, R3 represents an alkyl group having 6 or less carbon atoms)
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, dimethylacetamide, N-ethylacetamide, N, N-diethylacetamide, hexamethylphosphoric amide, (2) Representative examples include dimethyl sulfoxide as an oxide type, (3) acetonitrile as a nitrile type, and (4) γ-butyrolactone, N-methyl-2-pyrrolidone, ethylene carbonate, propylene carbonate, and the like as cyclic esters and amide types.

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 compound to which the present invention is applied is cyclopropanecarboxylic acid cyclopropane-1,1-
dicarboxylic acid, cyclobutanecarboxylic acid, cyclobutane-1,1-dicarboxylic acid, cyclopentanecarboxylic 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, phencholic acid, These include cyclooctatetraenecarboxylic acid, cyclohebutanecarboxylic acid, and cyclohebutanedicarboxylic acid.

Representative examples of N-alkyl-1-azabicycloalkanium compounds include N-alkyl quinuclidinium ethylkyl azabicyclo[2,2,11butanium N-alkyl-I-azabicyclo[3 ,2,2]nonanium N-alkyl-1-azabicyclo[3,3,l]/nanium N-alkyl-1-azabicyclo[3,2,I]octaniumethylkyl-1-azabicycloalkanium compound, for example , V. Brelove et al.: Annaren No. 53
Volume 2, page 83 (+937), et al.: Berichte No. 72
Volume, p. 1319 (1939), C. A. Grove et al.
Helvetica Chimi Power Acta Volume 37, Page 1672 (
N-alkyl-1-azabicloalkane is synthesized by the tripromide-ammonia method described in 1954) or by the double alkylation method, and this is N-alkylated with an alkyl norogenide by a conventional method. A halogenated N-alkyl-1-azabicycloalkanium compound can be obtained. This is subjected to electrodialysis using an ion exchange membrane to perform anion exchange for dehalogenation and desalination to hydrate N-
An aqueous solution of an alkyl-1-azabicycloalkanium compound is obtained. Equimole or 1/2 mole of the desired alicyclic mono- or dicarboxylic acid compound is added to the obtained N-alkyl-1-azabicycloalkanium compound aqueous solution, neutralized, and evaporated to dryness under reduced pressure. Mono- or di-N-alkyl-1-azabicycloalkanium salts of alicyclic mono- or dicarboxylic acid compounds can be obtained.

The electrolytic solution for an electrolytic capacitor according to the present invention is generally prepared by adding ethylkylene chloride of a desired alicyclic mono- or dicarboxylic acid compound to a solvent prepared by mixing an aprotic solvent with a polyhydric alcohol compound or its monoalkyl ether compound as required. −
Obtained by adding and dissolving an azabicycloalkanium salt.

(Example) The following describes examples of the electrolytic solution for electrolytic capacitors according to the present invention.
Table 1 shows the electrical conductivities of 2 Offi weight % solutions of the azavinchloralkanium compound salts 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 7
8fold ffi%, water] O%, ammonium adipate 12
%).

1. As can be seen from the results shown below, 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^) after 1000 hours after applying rated voltage at °C
) (dichotomous value).

In the comparison of the values in Table 2, the values 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, 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, m is 2 or 3, n is 2 or 3, p is 1, 2 or 3, R_1 is an alicyclic group having 3 to 10 carbon atoms, X is a hydrogen atom or a carboxyl group, or this group and the N-
N-alkyl-1- of an alicyclic mono- or dicarboxylic acid compound of a base with the same group as the alkyl-1-azabicyclo[m,n,p]alkanium group (R_2 represents an alkyl group having up to 6 carbon atoms) An electrolytic solution for an electrolytic capacitor containing an azabicyclo[m,n,p]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) Alicyclic mono- or dicarboxylic acid compounds include cyclopropane-1,1-dicarboxylic acid, cyclobutane-1,1-dicarboxylic acid,
The electrolytic solution for an electrolytic capacitor according to claim 1, which is dicarboxylic acid, hexahydrophthalic acid, or hexahydrobenzoic acid.