JP2011071394A - Electrolyte for driving electrolytic capacitor, and electrolytic capacitor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrolytic capacitor having high-temperature life characteristics stable over a long term, and excelling in low-temperature characteristics, and to provide a driving electrolyte used for the same. <P>SOLUTION: This electrolyte for driving an electrolytic capacitor is prepared by dissolving, as a solute, an organic carboxylic acid and/or its salt in a solvent containing an alkylanisole. As the alkylanisole, a substance is selected from a group consisting of ethylanisole, methylanisole, propylanisole, butylanisole and t-butylanisole to be used, and thereby the high-temperature life characteristic and the low-temperature characteristic of an electrolytic capacitor are improved. The content of the alkylanisole in the electrolyte is preferably 5.0-60.0 wt.%. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an electrolytic solution for driving an electrolytic capacitor and an electrolytic capacitor using the electrolytic solution, and particularly relates to an electrolytic solution that can realize an electrolytic capacitor that has stable long-term high-temperature life characteristics and good low-temperature characteristics. It is.

  An electrolytic capacitor is a capacitor that uses a metal called a valve metal such as aluminum, tantalum, or niobium as an electrode, and uses an oxide film obtained by anodizing as a dielectric.

In general, an aluminum electrolytic capacitor is obtained by winding an anode foil 1 having an etching process and an oxide film forming process having a structure as shown in FIGS. After the capacitor element 6 is formed and impregnated with an electrolytic solution, the capacitor element is housed in a bottomed cylindrical outer case 8.
A sealing body 9 is attached to the opening of the outer case 8 and sealed by drawing. You may have the element fixing material 17 which fixes the capacitor | condenser element 6 to the exterior case 8. FIG.
An anode terminal 13 and a cathode terminal 14 are formed on the outer end surface of the sealing body 9, and the lower ends of these terminals 13 and 14 are drawn out from the capacitor element 6 as an anode internal terminal 15 and a cathode internal terminal 16, respectively. The anode tab terminal 11 and the cathode tab terminal 12 are electrically connected.
Here, the anode tab terminal 11 is subjected to a chemical conversion treatment, while the cathode tab terminal 12 is not subjected to a chemical conversion treatment. Both of the tab terminals 11 and 12 are made of aluminum foil that has not been subjected to surface processing.

As an electrolytic solution for driving an electrolytic capacitor, ethylene glycol is used as a solvent for an electrolytic solution that requires high temperature and long life characteristics, and γ-butyrolactone is used as a solvent for an electrolytic solution that requires low temperature characteristics. In a solvent in which this is mixed at an appropriate ratio, a salt containing an imidazolinium cation or imidazolium cation of a cyclic amidine compound as a solute as a cation component and an acid conjugate base as an anion component is used as a solute (for example, the following) Patent Document 1).
Patent Document 2 below discloses an electrolytic solution obtained by dissolving a salt of a compound having an alkyl-substituted amidine group of phthalic acid and maleic acid as an electrolyte in an organic solvent containing γ-butyrolactone.

JP-A-8-32440 JP-A-8-32441

  However, due to the downsizing and thinning of electronic components, electrolytic capacitors are required to be downsized. On the other hand, there is a need for response to temperature changes and long-term reliability at high temperatures. The electrolytic solution for use cannot cope with high-temperature reliability, and the low-temperature characteristics are not satisfied in the in-vehicle field.

  The present invention has been made in view of the above-described present situation, and an object of the present invention is to provide an electrolytic capacitor having good high-temperature reliability and good low-temperature characteristics, and a driving electrolyte used in the electrolytic capacitor.

As a result of repeated studies to solve the above problems, the present inventor is to solve the above problems effectively by using a solvent containing a specific alkylanisole as the solvent of the electrolytic solution for driving the capacitor. The present invention was completed successfully.
That is, the present invention is an electrolytic solution for driving an electrolytic capacitor obtained by dissolving an organic carboxylic acid and / or a salt thereof as a solute in a solvent containing an alkylanisole,
The alkylanisole is selected from the group consisting of ethylanisole, methylanisole, propylanisole, butylanisole, and t-butylanisole.

  According to this configuration, the use of the above alkylanisole as a solvent in the electrolytic solution suppresses changes in capacitance and tan δ in the high-temperature life characteristics of the electrolytic capacitor, and also suppresses an increase in specific resistance at low temperatures. can do. Further, by using an organic carboxylic acid and / or a salt thereof as a solute (electrolyte), a low specific resistance and a high voltage resistance can be realized. Therefore, it is possible to provide an electrolytic capacitor that has stable high-temperature life characteristics over a long period of time and also has good low-temperature characteristics.

Furthermore, when the content of the alkylanisole in the driving electrolyte is in the range of 5.0 to 60.0 wt%, both the high temperature reliability and low temperature characteristics of the capacitor can be further improved.
As an example of the particularly preferred solvent of the present invention, a solvent containing the above alkylanisole and lactone can be mentioned.
The content of the organic carboxylic acid and / or salt thereof as a solute in the driving electrolyte is preferably 5.0 to 30.0 wt%.
A particularly preferred example of the solute is a quaternary salt of a cyclic amidine compound of an organic carboxylic acid.

  An electrolytic capacitor having a capacitor element impregnated with the driving electrolyte exhibits stable high-temperature life characteristics and good low-temperature characteristics over a long period of time.

  According to the present invention, using a specific alkyl anisole as the solvent in the electrolytic solution, by using an organic carboxylic acid and / or its salt as a solute, the change in capacitance and tanδ is suppressed at high temperatures application test, It is possible to provide an electrolytic capacitor that has stable electrical characteristics over a long period of time and also has good low-temperature characteristics.

It is a disassembled perspective view of an electrolytic capacitor element. It is principal part sectional drawing of an electrolytic capacitor.

The alkyl anisole in the present invention is an anisole having an ethyl group, a methyl group, a propyl group, a butyl group, or a tert-butyl group as an alkyl group, and can be represented by the following chemical formula (wherein R represents an alkyl group). Show). The substitution position of the alkyl group may be any of the 2, 3, and 4 positions.

The electrolytic solution for driving an electrolytic capacitor used in the present invention preferably contains one or more organic carboxylic acids or salts thereof as a solute in a solvent obtained by mixing alkylanisole and one or more other solvents.
At this time, the content ratio of the alkylanisole is preferably 5.0 to 60.0 wt% of the entire electrolyte solution, and more preferably 10.0 to 60.0 wt% of the entire electrolyte solution. .

  Other solvents to be mixed with alkyl anisole in the present invention, alcohols, ethers, amides, oxazolidinones, lactones, nitriles, carbonates, one or more can be mentioned selected from the group consisting of sulfones. Specific examples of the solvent are as follows, and two or more kinds can be used in combination.

  Examples of alcohols include 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, and hexitol.

As ethers, 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 diethyl Examples include ether.
In addition, examples of the high molecular weight material include polyalkylene glycols such as polyethylene glycol and polypropylene glycol and copolymers thereof (hereinafter referred to as polyalkylene glycol).

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

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

  As lactones, .gamma.-butyrolactone, alpha-acetyl -γ- butyrolactone, beta-butyrolactone, .gamma.-valerolactone, .delta.-valerolactone.

  Examples of nitriles include acetonitrile, acrylonitrile, adiponitrile, and 3-methoxypropionitrile.

  Examples of carbonates include ethylene carbonate and propylene carbonate.

  Examples of the sulfones include dimethyl sulfone, ethyl methyl sulfone, diethyl sulfone, sulfolane, 3-methyl sulfolane, and 2,4-dimethyl sulfolane.

  Examples of other solvents include water, N-methyl-2-pyrrolidone, dimethyl sulfoxide, 1,3-dimethyl-2-imidazolidinone, toluene, xylene, paraffins, and the like.

The electrolytic solution used in the present invention may contain various additives as necessary. The purpose of adding the additive is various, and examples thereof include improvement of thermal stability, suppression of electrode deterioration such as hydration, improvement of withstand voltage, suppression of gas generation, and resistance to halides.
Although there is no restriction | limiting in particular in content of an additive, it is preferable that it is the range of 0.01-20.0 wt%, More preferably, it is the range of 0.01-10.0 wt%.

  Examples of such additives include nitro compounds such as p-nitrophenol, m-nitroacetophenone, p-nitrobenzoic acid, p-nitrobenzyl alcohol, p-nitrocresol, p-nitrotoluene, orthophosphoric acid, phosphorous acid , hypophosphorous acid, pyrophosphoric acid, polyphosphoric acid, methyl phosphate, ethyl phosphate, butyl phosphate, isopropyl phosphate, dibutyl phosphate, phosphoric acid compounds such as phosphoric acid dioctyl, boric acid and boric its complex compounds, etc. Acid compounds, mannitol, sorbitol, xylitol, pentaerythritol, polyhydric alcohols such as polyvinyl alcohol, colloidal silica, aluminosilicate, silicone compounds (for example, hydroxy-modified silicone, amino-modified silicone, carboxyl-modified silicone which is a reactive silicone, Alcohol-modified silicones, epoxy-modified silicone, etc.) or a silane coupling agent (e.g., 3-glycidoxypropyltrimethoxysilane, vinyl trimethoxysilane, ethyl triethoxysilane, etc.) silicon compound, and the like.

As the solute (electrolyte) used in the electrolytic solution of the present invention, an organic carboxylic acid and / or a salt thereof is used from the viewpoints of specific resistance and voltage resistance.
Here, the content ratio of the organic carboxylic acid or the organic carboxylate is preferably 5.0 to 30.0 wt% of the entire electrolyte solution, and 10.0 to 25.0 wt% of the entire electrolyte solution. Is more preferred.

  Examples of organic carboxylic acids used as solutes in the present invention include phthalic acid, maleic acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanoic acid, benzoic acid, 2-methyl azelaic acid, 1,6 Examples include -decanedicarboxylic acid, 5,6-decanedicarboxylic acid, 2-butyloctanedioic acid, 7-vinylhexadecane-1,16-dicarboxylic acid, and the like. In order to obtain a more remarkable effect, two or more organic carboxylic acids may be used. Examples of particularly preferred organic carboxylic acids include phthalic acid and maleic acid.

  Examples of the organic carboxylic acid salts include ammonium salts, primary amine salts such as methylamine, ethylamine and t-butylamine, secondary amine salts such as dimethylamine, ethylmethylamine and diethylamine, trimethylamine, diethylmethylamine, Tertiary amine salts such as ethyldimethylamine and triethylamine, quaternary ammonium salts such as tetramethylammonium, triethylmethylammonium and tetraethylammonium, imidazole monocyclic compounds, compounds having a 2-imidazoline ring, compounds having a tetrahydropyrimidine ring, 1 And quaternary salts of cyclic amidine compounds such as 1,3-dimethylimidazolinium, 1,2,3-trimethylimidazolinium and 1,2,3,4-tetramethylimidazolinium.

Hereinafter, the present invention will be described in more detail with reference to examples. The electrolyte compositions of Examples and Comparative Examples were as shown in Table 1.
[Examples 1-1 to 1-7] Examination of blending amount of alkyl anisole / solute: 1-ethyl-2,3-dimethylimidazolinium hydrogen phthalate 20.0 wt%
-Solvent: 4-ethylanisole 4.0-70.0 wt%
γ-butyrolactone 10.0-76.0 wt%
With the above composition, the mixing amount of 4-ethylanisole was changed, and the specific resistance at 30 ° C. and −40 ° C. was measured.

[Examples 1-8 to 1-13] Comparison by type of alkylanisole As the alkylanisole, 3-ethylanisole, 2-ethylanisole, 4-methylanisole, 4-propylanisole, 4-butylanisole or 4-t- An electrolyte solution was prepared in the same manner as in Example 1-4 (alkylanisole content: 20.0 wt%) except that butylanisole was used, and the specific resistance at 30 ° C. and −40 ° C. was measured in the same manner as described above. did.

(Comparative Example 1)
The above 4-ethylanisole was not used, and the solvent used was a mixture of 60.0 wt% γ-butyrolactone and 20.0 wt% ethylene glycol, and the solute was the same as in Examples 1-1 to 1-13. The specific resistance at 30 ° C. and −40 ° C. was measured.

[Examples 2-1 to 2-7] Examination of blending amount of 4-ethylanisole (change of solute species)
Electrolysis in which the amount of 4-ethylanisole was varied in the same manner as in the above example except that hydrogen maleate-1,2,3,4-tetramethylimidazolinium 20.0 wt% was used as the solute. A liquid was prepared and the specific resistance at 30 ° C. and −40 ° C. was measured.

(Comparative Example 2)
The above 4-ethylanisole was not used, and a mixture of 60.0 wt% γ-butyrolactone and 20.0 wt% ethylene glycol was used as the solvent, and the solute was the same as in Examples 2-1 to 2-7. The specific resistance at 30 ° C. and −40 ° C. was measured.

  Table 1 shows the results of measuring specific resistance at 30 ° C. and −40 ° C. for the electrolyte solutions prepared in Examples 1-1 to 1-13, 2-1 to 2-7, and Comparative Examples 1 and 2 above. .

  In addition, using the electrolytes of Examples 1-1 to 1-13, 2-1 to 2-7, and Comparative Examples 1 and 2, the rated voltage is 6.3 V, the capacitance is 1000 μF (case size φ10 × 12.5 mmL) capacitor was fabricated, and a high temperature load test was performed by applying a rated voltage of 6.3 V for 1000 hours at 125 ° C. The results are shown in Table 1.

  As is clear from Table 1, the Examples of the present invention, compared with Comparative Examples 1 and 2, reduced the tan δ change in the high temperature load test while reducing the specific resistance at −40 ° C. The improvement effect has appeared. Among them, Examples 1-2 to 1-6, 1-8 to 1-13, and 2-2 to 2-6 in which the alkylanisole is 5.0 to 60.0 wt% are more preferable.

  Here, as a solute dissolved in said solvent, in the above embodiment, hydrogen phthalate 1-ethyl-2,3-dimethyl imidazolinium or hydrogen maleate 1,2,3,4-tetramethyl imidazolinium, However, other organic carboxylic acids or salts thereof can also be used, and a quaternary salt of a cyclic amidine compound of an organic carboxylic acid is particularly preferable. Moreover, it is preferable that content of the said solute in electrolyte solution for a drive shall be 5.0-30.0 wt%.

  The present invention is not limited to the above embodiments, the solvent described above, if the single or multiple use solutes, and also when mixed with other additives mentioned above, a similar low-temperature characteristics, high-temperature Reliability improvement effect was obtained.

DESCRIPTION OF SYMBOLS 1 Anode foil 2 Cathode foil 3 Separator 6 Capacitor element 8 Exterior case 9 Sealing body 10 Caulking 11 Anode tab terminal 12 Cathode tab terminal 13 Anode terminal 14 Cathode terminal 15 Anode internal terminal 16 Cathode internal terminal 17 Element fixing agent

Claims (6)

An electrolytic solution for driving an electrolytic capacitor obtained by dissolving an organic carboxylic acid and / or a salt thereof as a solute in a solvent containing an alkylanisole,
An electrolytic solution for driving an electrolytic capacitor, wherein the alkyl anisole is selected from the group consisting of ethyl anisole, methyl anisole, propyl anisole, butyl anisole, and t-butyl anisole.   2. The electrolytic solution for driving an electrolytic capacitor according to claim 1, wherein the content of the alkylanisole in the driving electrolytic solution is 5.0 to 60.0 wt%.   The electrolytic solution for driving an electrolytic capacitor according to claim 1, wherein the solvent is a solvent containing the alkyl anisole and lactone.   The electrolytic solution for driving an electrolytic capacitor according to any one of claims 1 to 3, wherein the content of the solute in the electrolytic solution for driving is 5.0 to 30.0 wt%.   The electrolytic solution for driving an electrolytic capacitor according to any one of claims 1 to 4, wherein the solute is a quaternary salt of a cyclic amidine compound of an organic carboxylic acid.   An electrolytic capacitor comprising a capacitor element impregnated with the driving electrolyte solution according to claim 1.

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