JP2006344861A - Electrolyte for driving electrolytic capacitor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tertial ammonium salt based electrolyte having high conductivity and enhancing reliability of aluminium electrolytic capacitor. <P>SOLUTION: In an electrolyte for driving an aluminium electrolytic capacitor, a solvent principally comprising γ-butyrolactone is mixed with 15-50 wt.% of a salt of N,N-dimethy-N-(2-methoxy ethyl) ammonium ions of tertial amine represented by a chemical formula, and inorganic acid anions such as tetrafluoroborate ions as solute. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an electrolytic solution for driving an electrolytic capacitor (hereinafter referred to as an electrolytic solution).

  Conventionally, high-frequency, low-impedance aluminum electrolytic capacitors have a highly conductive electrolytic solution using a quaternary ammonium salt of carboxylic acid such as phthalic acid or maleic acid as a solute in a solvent mainly composed of γ-butyrolactone. Known (for example, Patent Document 1).

  However, when manufacturing an aluminum electrolytic capacitor using a quaternary ammonium salt electrolyte, if the lead portion protruding from the capacitor element is sealed with the lead hole portion of the sealing rubber being passed, the base component of the quaternary ammonium salt is It is said that the cathode side lead hole part and lead part are deteriorated, and the electrolyte leaks from the cathode side lead hole part of the sealing rubber.

As a method for avoiding such liquid leakage, it has been studied to use a tertiary ammonium salt electrolyte instead of a quaternary ammonium salt electrolyte. Examples of such an electrolyte include triethylamine salts and Some use a pentaalkylguanidine salt as a solute (see, for example, Patent Document 2).
JP-A 62-145713 JP-A-9-283379

  However, since the tertiary ammonium salt electrolyte has a lower electrical conductivity than the quaternary ammonium salt electrolyte, there is a problem that desired impedance characteristics cannot be obtained.

  In view of the above problems, an object of the present invention is to provide an electrolytic solution that is a tertiary ammonium salt system and has high conductivity and can improve the reliability of an aluminum electrolytic capacitor. .

  The electrolytic solution for driving the aluminum electrolytic capacitor of the present invention comprises N, N-dimethyl-N- (2-methoxyethyl) ammonium ion which is a tertiary amine as a solute with respect to a solvent mainly composed of γ-butyrolactone. It is characterized by blending a salt with an inorganic acid anion.

  Here, N, N-dimethyl-N- (2-methoxyethyl) ammonium ion is represented by the following chemical formula.

  In the present invention, the inorganic acid anion constituting the salt with the N, N-dimethyl-N- (2-methoxyethyl) ammonium ion is, for example, a tetrafluoroborate ion.

  In the present invention, the concentration of the solute is preferably 15% by weight or more with respect to the entire electrolytic solution. If comprised in this way, the electrical conductivity equivalent to or more than a quaternary ammonium type electrolyte solution can be obtained.

  As a solvent in the electrolytic solution of the present invention, γ-butyrolactone is a main component, but two or more kinds may be used in combination with the following sub-solvent.

  In the present invention, alcohols used as a co-solvent include, for example, methyl alcohol, ethyl alcohol, propyl alcohol, butyl alcohol, diacetone alcohol, benzyl alcohol, amyl alcohol, furfuryl alcohol, ethylene glycol, propylene glycol, diethylene glycol. Hexylene glycol, glycerin, hexitol and the like.

  The ethers include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, ethylene glycol phenyl ether, tetrahydrofuran, 3-methyltetrahydrofuran, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, diethylene glycol. For example, diethyl ether.

  As amides, N-methylformamide, N, N-dimethylformamide, N-ethylformamide, N, N-diethylformamide, N-methylacetamide, N, N-dimethylacetamide, N-ethylacetamide, N, N-diethyl Examples include acetamide and hexamethylphosphoric amide.

  Examples of oxazolidinones include N-methyl-2-oxazolidinone and 3,5-dimethyl-2-oxazolidinone.

  Examples of lactones include α-acetyl-γ-butyrolactone, β-butyrolactone, γ-valerolactone, and δ-valerolactone.

  Nitriles include acetonitrile, acrylonitrile, adiponitrile, 3-methoxypropionitrile and the like.

  Examples of carbonates include ethylene carbonate and propylene carbonate.

  Other organic solvents include N-methyl-2-pyrrolidone, dimethyl sulfoxide, sulfolane, 1,3-dimethyl-2-imidazolidinone, toluene, xylene, paraffins and the like.

  Various additives can be added to the electrolytic solution of the present invention as necessary. Examples of the additive include polyhydric alcohols such as mannitol and sorbitol, phosphoric acid or phosphoric acid derivatives, boric acid derivatives, colloidal silica, and nitro compounds.

  In the electrolytic solution to which the present invention is applied, a salt of a tertiary amine N, N-dimethyl-N- (2-methoxyethyl) ammonium ion and an inorganic acid anion is blended as a solute with respect to an organic polar solvent. Therefore, high electrical conductivity (low specific resistance) is obtained. In addition, the aluminum electrolytic capacitor using the electrolytic solution to which the present invention is applied has a small increase in tan δ even when a high temperature application test is performed in addition to a small initial tan δ. Therefore, according to the present invention, the initial characteristics, reliability and lifetime of the aluminum electrolytic capacitor can be improved.

  In the electrolytic solution according to the present invention, N, N-dimethyl-N- (2-methoxyethyl) ammonium ion, which is a tertiary amine, and boron tetrafluoride as a solute with respect to a solvent mainly composed of γ-butyrolactone. A salt with an anion of an inorganic acid such as an acid is blended, and the concentration of the solute is, for example, 15 to 50% by weight with respect to the entire electrolytic solution.

Since such an electrolytic solution has high conductivity (low specific resistance), when used in an aluminum electrolytic capacitor, the initial tan δ is small, and even when a high temperature application test is performed, the increase in tan δ is small. Therefore, the initial characteristics, reliability and life of the aluminum electrolytic capacitor can be improved.
Further, when producing an aluminum electrolytic capacitor using the tertiary ammonium salt electrolyte according to the present invention, even if the lead portion protruding from the capacitor element is sealed in a state where the lead hole portion of the sealing rubber is passed through, Since the base component of the ammonium salt does not deteriorate the lead hole portion or lead portion on the cathode side, the electrolyte does not leak from the lead hole portion on the cathode side of the sealing rubber.

  Hereinafter, based on an Example, this invention is demonstrated more concretely. First, an electrolytic solution was prepared with the composition shown in Table 1, and the specific resistance of the electrolytic solution at 30 ° C. was measured. The results are shown in Table 1.

  As is clear from Table 1, the electrolyte solutions according to Examples 1 to 7 of the present invention have a specific resistance compared to the electrolyte solutions according to Conventional Examples 1 to 7 when compared with compositions having substantially the same solute concentration. Is low.

  In the electrolytic solution to which the present invention is applied, when the solute concentration is less than 15% by weight (Examples 1 and 2), the specific resistance value cannot be significantly reduced, and more than 55% by weight (Example 8). ) Is insoluble, the solute concentration is preferably 15 to 50% by weight.

  Next, 10 6.3V-1000 μF (φ10 × 12.5 mmL) aluminum electrolytic capacitors were prepared using the electrolyte solutions having the respective compositions shown in Table 1, and initial characteristics were measured for tan δ and equivalent series resistance. Thereafter, a high-temperature application test (105 ° C., 1000 hours, 6.3 V application) was performed, and tan δ and equivalent series resistance after the test were measured. The results are shown in Table 2.

  As is apparent from Table 2, the aluminum electrolytic capacitors using the electrolytic solutions according to Examples 1 to 7 of the present invention are aluminum electrolytic capacitors using conventional tertiary amine salt-based electrolytic solutions (Conventional Examples 6 and 7). Compared with the capacitor, it can be seen that the increase in tan δ and equivalent series resistance is remarkably suppressed in the high temperature application test, and excellent reliability is exhibited.

  Next, using the electrolytic solutions according to Examples 1 to 7 of the present invention and the electrolytic solution of Conventional Example 5, 100 6.3V-1000 μF (φ10 × 12.5 mmL) aluminum electrolytic capacitors were produced. Then, 6.3 V was applied for 2000 hours under a high temperature and high humidity condition of a temperature of 85 ° C. and a relative humidity of 85%, and the presence or absence of liquid leakage from the lead hole portion of the sealing portion was examined. The results are shown in Table 3.

  As is apparent from Table 3, the aluminum electrolytic capacitor using the electrolytic solutions according to Examples 1 to 7 of the present invention is an aluminum electrolysis using the electrolytic solution according to Conventional Example 5 using a quaternary ammonium salt as a solute. Unlike the capacitor, it can be seen that there is no leakage of liquid from the lead hole portion of the sealing portion, and it shows excellent reliability.

  In addition, this invention is not limited to the said Example, The same effect can be acquired even in the electrolyte solution which melt | dissolved various compounds described previously individually or in multiple numbers.

Claims (3)

A salt of N, N-dimethyl-N- (2-methoxyethyl) ammonium ion, which is a tertiary amine represented by the following chemical formula, and an inorganic acid anion as a solute with respect to a solvent mainly composed of γ-butyrolactone An electrolytic solution for driving an electrolytic capacitor comprising:

  2. An electrolytic solution for driving an electrolytic capacitor, wherein the inorganic acid anion according to claim 1 is a tetrafluoroborate ion.   3. The electrolytic solution for driving an electrolytic capacitor, wherein the concentration of the solute according to claim 1 or 2 is 15 to 50% by weight with respect to the whole electrolytic solution.