JP2732404B2 - Electrolyte for electrolytic capacitors - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an electrolytic solution used for an electrolytic capacitor, and more particularly to an electrolytic solution using an aprotic solvent as a main solvent.

[Conventional technology]

Electrolytic capacitors use a valve metal such as aluminum or tantalum having an insulating oxide film formed on the surface for the electrode foil, and use the oxide film layer as a dielectric, and an electrolyte layer on the surface of the oxide film layer. And an electrode for current collection, which is usually called a cathode, is arranged.

As described above, the electrolytic solution for the electrolytic capacitor directly contacts the dielectric 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, the characteristics of the electrolytic solution are a major factor influencing the characteristics of the electrolytic capacitor. For example, when the conductivity of the electrolytic solution is low, there is a disadvantage that the equivalent series resistance inside the electrolytic capacitor is increased and the high-frequency characteristics and the loss characteristics are deteriorated.

Conventionally, in order to improve high-frequency characteristics, loss characteristics, etc., an electrolyte having a high electrical conductivity is used in which an organic acid such as adipic acid or a salt thereof is dissolved in glycols such as ethylene glycol or alcohols. I have.

[Problems to be Solved by the Invention] However, demands for improving and improving the performance of electrolytic capacitors have increased due to the recent increase in the range of use of electronic devices, and the current conductivity of electrolytic solutions cannot be said to be sufficient. In particular, in the case of the current electrolytic solution, when the desired conductivity cannot be obtained, or when using an electrolyte having low solubility, for example, water is intentionally added to improve the conductivity. .

However, recently, in electrolytic capacitors that require long-term use in a wide temperature environment that exceeds conventional products, the presence of moisture in the electrolytic solution deteriorates the dielectric film layer and lowers the internal vapor pressure of the electrolytic capacitor. This leads to abnormal rise, damage to the sealing body, deterioration of life due to evaporation of the electrolytic solution, and the like, making it difficult to maintain stable characteristics for a long period of time.

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 mainly composed of an aprotic solvent, and to maintain stable characteristics for a long period of time. Therefore, the object is to improve the reliability of the electrolytic capacitor.

[Means for solving the problem]

The present invention provides an electrolytic solution for an electrolytic capacitor comprising: (1) a solvent mainly containing an aprotic solvent; (Wherein m = 3-6, n = 3-6, R is an alkyl group having 1 to 6 carbon atoms, R ₁ is an alkenylene group having 1 to 10 carbon atoms, X is a hydrogen atom or N-alkyl-
Mono- or di-N-alkyl-1-azabicyclo [m, n, 0] of an aliphatically unsaturated dicarboxylic acid compound of 1-azabicyclo [m, n, 0] alkanium compound
It is characterized by containing an alkanium compound salt as an electrolyte.

Examples of the aprotic solvent used include: (1) N-methylformamide, N,
N-dimethylformamide, N-ethylformamide,
N, N-diethylformamide, N-methylacetamide, N, N-dimethylacetamide, N-ethylacetamide, N, N-diethylacetamide, hexamethylphosphoramide, (2) dimethyl sulfoxide as an oxide system, (3) nitrile system Representative examples include acetonitrile, (4) cyclic esters, and amides such as γ-butyrolactone, N-methyl-2-pyrrolidone, ethylene carbonate, and propylene-carbonate.

Further, the polyhydric alcohol compound which 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), and 100% of the aprotic solvent is suitable, but up to about 50% of the polyhydric alcohol compound is substantially It may be used as appropriate because it can avoid product deterioration.

Specific examples of specific aliphatic unsaturated dicarboxylic acids include maleic acid, citraconic acid, glutaconic acid, itaconic acid, allylmalonic acid, terraconic acid, fumaric acid, mesaconic acid, and muconic acid.

Further, typical specific examples of the N-alkyl-1-azabicyclo [m, n, 0] alkanium compound are represented by the following structural formula.

Mono or di-N-alkyl-1 used in the present invention
1-Azabicyclo [m, n, 0] alkanium compound used as a raw material for synthesis of azabicyclo [m, n, 0] alkanium compound, for example, pyrrolidine, F. Sorm, J. brandejs, Coll
ection Czechoslov.Chem.Commun. Volume 12, p. 444 (194
It is made by the following reaction described in 7).

When this is N-methylated with an alkyl halide, for example, methyl iodide by a conventional method, N-methylpyrrolidinium iodide can be obtained. This is subjected to electrodialysis using an ion-exchange membrane to conduct anion exchange and deiodination and desalting to obtain an aqueous solution of N-methylpyrrolidinium hydroxide. Equimolar or 1/2 mole of the desired aliphatic unsaturated dicarboxylic acid compound is added to this aqueous solution, neutralized, and evaporated to dryness under reduced pressure to obtain an aliphatic unsaturated dicarboxylic acid compound, N-methylpyrrolidinium. Salt can be obtained.

The electrolytic solution for an electrolytic capacitor according to the present invention generally comprises a mono- or di-hydric compound of a desired aliphatic unsaturated dicarboxylic acid in a solvent obtained by mixing a polyhydric alcohol compound or a monoalkyl ether compound thereof as necessary with an aprotic solvent. -N-alkyl-1-azabicyclo [m, n, 0] alkanium compound salt is added and dissolved.

〔Example〕

Hereinafter, examples of the electrolytic solution for the electrolytic capacitor according to the present invention, various aprotons of mono- or di-N-alkyl-1-azabicyclo [m, n, 0] alkanium compound salt of a compound of an aliphatic unsaturated dicarboxylic acid Table 1 shows the conductivity of the solvent or the ethylene glycol solution with the solvent.

 Note that a standard electrolytic solution is shown as a conventional example.

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

Next, each of the electrolyte solutions of Examples 1 to 10 and Comparative Example was used.
Ten electrolytic capacitors were manufactured and their characteristics were compared.

The manufactured electrolytic capacitors were made by using aluminum foil for the anode and the cathode, and wound into a cylindrical capacitor element with a separator paper sandwiched therebetween, and impregnated with the electrolytic solution of each of the Examples and Comparative Examples. It is housed in an outer case and sealed.

Each uses the same capacitor element, and has a rated voltage of 16 V and a rated capacity of 180 μF.

Table 2 shows the initial values of these electrolytic capacitors and the values of 110
The capacitance value (CAP: μF), the tangent of the loss angle (tan δ), and the leakage current (LC: μA) in two minutes are shown after 1000 hours from the application of the rated voltage at ° C.

As is evident from the results of this test, the loss, that is, the value of tan δ, is lower than that of the conventional electrolyte because the conductivity of the electrolyte of the present invention is high.

In addition, since water is essentially not included, it is understood that its characteristics change little even in a low-temperature environment, and that the appearance abnormalities and the rate of decrease in capacitance due to an increase in internal pressure under a high-temperature load condition are extremely small. Is done.

〔The invention's effect〕

The electrolytic capacitor using the electrolytic solution according to the present invention can maintain a low loss value and stable characteristics for a long time even in a wide temperature environment, so that it is used at a high frequency, and high efficiency switching is required. The present invention can be used for a power supply device such as a regulator and various electric devices used at a high temperature for a long time.

Claims (1)

(57) [Claims] [1] In a solvent mainly composed of an aprotic solvent, a general formula: (Wherein m = 3-6, n = 3-6, R is an alkyl group having 1 to 6 carbon atoms, R ₁ is an alkenylene group having 1 to 10 carbon atoms, X is a hydrogen atom or N-alkyl-
Mono- or di-N-alkyl-1-azabicyclo [m, n, 0] of an aliphatically unsaturated dicarboxylic acid compound of 1-azabicyclo [m, n, 0] alkanium compound
An electrolytic solution for electrolytic capacitors containing an alkanium compound salt as an electrolyte.