JPH0269917A - 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,plarcanium compound salt of fatty saturated monocarboxylic 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, n: 2 or 3, p: 1, 2 or 3, R: 30-0C alkenyl group or alkadienyl group, and R2: 6-0C alkyl group.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention contains an ethylkyl I-azabicycloalkanium compound salt of an aliphatic unsaturated monocarboxylic acid as an electrolyte 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.

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 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.

Against this background, electrolytes with high conductive dust have been selected, and conventionally known electrolytes with high conductive dust 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) 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 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 electrolytic capacitors by providing a substantially non-aqueous high-conductivity electrolytic solution containing an aprotic solvent as a main component, and to achieve stable characteristics. The objective is to improve the (i In properties) of an electrolytic capacitor by maintaining the (i In ) for a long period of time.

(Means for Solving the Problems) As a result of intensive research into an electrolyte that is essentially an aqueous electrolyte mainly composed of an aprotic solvent and provides high electrical conductivity, the present inventors have found that an electrolyte containing no aliphatic N of saturated monocarboxylic acid
The present invention was achieved by discovering that -alkyl-1-azabicycloalkanium compound salts have high solubility in aprotic solvents, have a high degree of dissociation, and impart high electrical conductivity.

That is, the electrolytic solution for electrolytic capacitors according to the present invention contains a general formula (where m is 2 or 3, n is 2 or 3, p is 1, 2 or 3, R N-alkyl-1- of an aliphatic unsaturated monocarboxylic acid (represents an alkenyl group or alcadenyl group having up to 30 carbon atoms, R2 represents an alkyl group having up to 6 carbon atoms)
It is characterized by containing an azabicyclo[m, n, p]alkanium compound salt as an electrolyte.

The aprotic solvents used include (1) tomethylformamide, N, as an amide type;
N-dimethylformamide, N-ethylformamide,
N,N-ethylformamide, N-methylacetamide, N,N-methylacetamide, N-ethylacetamide, N,N-diethylacetamide, hexamethylphosphoric amide, (2) dimethylforfoquine as an oxide system, (3) Acetonitrile as a nitrile type, (4) γ as a cyclic ester and amide type.
Representative examples thereof include -butyrolactone, N-methyl-2-pyrrolidone, ethylene carbonate, and polyethylene 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 alfur compound, and the dihydric alcohol compound is ethylene glycol, and the dihydric alcohol monoalkyl ether compound is preferably a dihydric alcohol compound or a monoalkyl ether of a dihydric alfur compound. 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 aliphatic unsaturated monocarboxylic acid compounds targeted by the present invention include acrylic acid, crotonic acid, isocrotonic acid, vinyl acetic acid, methacrylic acid, angelic acid, tiglic acid, allyl acetate, α-ethyl crotonic acid, hexenoic acid, and heptenoic acid. , octenoic acid, /anonic acid, decenoic acid, donacenic acid, tzuic acid, undecenoic acid, oleic acid, elaidic acid,
Erucic acid, brassic acid, lumeccitric acid, sorbic acid,
linoleic acid, etc., but are not limited to these.

Representative examples of N-alkyl-1-azabicycloalkanium compounds are: N-alkyl quinuclidinium ethylkyl azabicyclo[2,2,11hebutanium N-alkyl-1-aza N-alkyl-
1-Azabicyclo[3,2,2]nonanium Bicyclo[3,3,1]nonanium N-alkyl-1-azabicyclo[3,2,l]octanium i'' N-alkyl-1-azabicycloalkanium compound is For example, ■, Prelogue et al.: Annaren Vol. 532, p. 83 (1937), He et al.: Berichte Vol. 72,
No. 1319 (1939), C. A. Grove et al. Helvetica Chimica Acta Vol. 37, No. 1672 (195
N-alkyl-1-azabicycloalkane is synthesized by the tripromide-ammonia method described in 4) or by the double alkylation method, and this is N-alkylated with an alkyl halogenide by a conventional method to obtain the corresponding halogen. chloride alkyl 1
-Azabicycloalkanium compounds can be obtained. This is subjected to electrodialysis using an ion exchange membrane and desalted with a denorogen for anion exchange to obtain an aqueous solution of an N-alkyl-1-azabicycloalkanium hydroxide compound. Equimolar moles of the desired aliphatic unsaturated monocarboxylic acid are added to the obtained N-alkyl azabicycloalkanium compound aqueous solution, a neutralization reaction is carried out, and the aliphatic unsaturated monocarboxylic acid is evaporated to dryness under reduced pressure. mono-N-alkyl-1-
Azabicycloalkanium salts can be obtained.

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 required, and adding an ethylkyl compound of a desired aliphatic unsaturated monocarboxylic acid to the solvent. - Obtained by adding and dissolving an azabicycloalkanium salt.

(Example) The following describes examples of the electrolyte solution for electrolytic capacitors according to the present invention.
Table 1 shows the conductivities of 20% by weight solutions of azabicycloalkanium compound salts in various aprotic solvents or with ethylene glycol or methyl cellosolve (ethylene glycol monomethyl ether). In addition, as a comparative example, a conventional standard electrolyte (ethylene glyfluor 8v
tilt%, water 10%, ammonium adipate A 12%
) is shown.

It represents the capacitance value (μF) of the flute player, the tangent of loss angle (tan δ), and the leakage current (μ8) (2-minute value).

As can be seen from the results in section 2 and 2, 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 1-10 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 and 85°
1000 hours elapsed after applying the rated voltage at C. 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, the tan δ value, is lower than that of the conventional electrolyte.

In addition, since it essentially does not contain water, there is no appearance abnormality or decrease in capacitance due to an increase in internal pressure even when placed under high temperature load conditions, and when comparing the initial value and characteristic value after 1000 hours,
The one according to the invention has very little variation.

(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.

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, N-alkyl-1 of aliphatic unsaturated monocarboxylic acid (R represents an alkenyl group or alkadienyl group having 30 or less carbon atoms, R_2 represents an alkyl group having 6 or less 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) The electrolytic solution for an electrolytic capacitor according to claim 1, wherein the aliphatic unsaturated monocarboxylic acid compound is crotonic acid, angelic acid, tiglic acid, or α-ethylcrotonic acid.