JP2007080888A - Electrolyte for electrolytic capacitor, and electrolytic capacitor using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To form a conductive polymer layer containing dopant in a capacitor element that is wound via a separator, and to suppress an increase in ESR in an electrolytic capacitor, where the gap between the conductive polymer layers is dipped into an electrolyte, at the lapse of time in the electrolytic capacitor using the winding type capacitor element. <P>SOLUTION: In the electrolyte for electrolytic capacitors used for the electrolytic capacitor, the conductive polymer layer is formed in the capacitor element in which an anode formation foil and a counter cathode foil are wound via the separator and the gap between the conductive polymer layers is dipped into the electrolyte. In the electrolyte, the molar ratio between an acid constituent and a basic constituent that are electrolyte constituents of the electrolyte is set so that an acid is excessive. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an electrolytic solution for an electrolytic capacitor and an electrolytic capacitor using the same.

With the increase in the frequency of electronic equipment, there is a demand for a large capacity electrolytic capacitor that is excellent in equivalent series resistance (hereinafter referred to as ESR) characteristics in the high frequency region even in an electrolytic capacitor that is an electronic component used in the electronic device. Recently, in order to reduce ESR in the high frequency region, an electrolytic capacitor impregnated with a conductive polymer containing a dopant agent having high electrical conductivity and an electrolytic solution has been proposed. (For example, see Patent Document 1)
Japanese Patent Laid-Open No. 11-186110

  However, since the conductive polymer layer containing the dopant agent has a so-called dedoping phenomenon in which the dopant agent escapes from the conductive polymer layer in the electrolytic solution, the electrical conductivity of the conductive polymer layer is reduced due to the dedoping phenomenon. The electrolytic capacitor has a problem that the ESR of the electrolytic capacitor gradually increases.

  Therefore, the present invention solves such a problem, and a conductive polymer layer containing a dopant is formed in a capacitor element that is wound through a separator that is wound through a separator. It is an object of the present invention to suppress an increase in ESR with the passage of time of an electrolytic capacitor in which an electrolytic solution is impregnated with an electrolytic solution in a gap between conductive polymers.

As a result of intensive studies to solve the above-mentioned problems, the present inventors have reached the present invention.
That is, in the present invention, a conductive polymer layer is formed in a capacitor element formed by winding an anodized foil and a counter cathode foil through a separator, and an electrolytic solution is impregnated in the gap between the conductive polymer layers. An electrolytic solution for an electrolytic capacitor used for an electrolytic capacitor, wherein the molar ratio of an acid component and a base component that are electrolyte components of the electrolytic solution is acid-excess; and a capacitor An electrolytic capacitor characterized in that an element is impregnated with a conductive polymer and the electrolytic solution.

  In the capacitor element, a conductive polymer layer containing a dopant agent is formed, which serves the intended purpose of reducing ESR in an electrolytic capacitor impregnated with an electrolytic solution between electrodes, and suppresses the dedoping phenomenon. As a result, an increase in ESR over time in the electrolytic capacitor can be suppressed, so that a long-life and highly reliable electrolytic capacitor can be provided.

In the electrolytic solution of the present invention, a conductive polymer layer containing a dopant agent is formed in a capacitor element formed by winding an anodized foil and a counter cathode foil with a separator interposed between the anodized foil and the cathode foil. It is used for an electrolytic capacitor that is impregnated with an electrolytic solution.
The conductive polymer layer is preferably formed all over the surface of the anodized foil, the surface of the counter cathode foil, and the surface of the separator in the capacitor element, but only on the surface of the anodized foil and the surface of the counter cathode foil. It may be formed.

The electrolytic capacitor is produced as follows, for example.
In the electrolytic capacitor according to the embodiment of the present invention, a wound capacitor element 7 as shown in FIG. 1 is used. The wound capacitor element includes an anodized foil 1 obtained by subjecting a foil made of a valve metal such as aluminum, tantalum, niobium, and titanium to an etching process for roughening and a chemical conversion process for forming a dielectric film. The counter cathode foil 2 is formed by winding it through a separator 3. Lead wires 51 and 52 are attached to the anodized foil 1 and the counter cathode foil 2 via lead tabs 61 and 62, respectively. Reference numeral 4 denotes a winding tape.

Then, after impregnating the wound capacitor element with a monomer that becomes a conductive polymer by oxidative polymerization, such as pyrrole or aniline or a derivative thereof, the capacitor element is placed in an aqueous solution of an oxidizing agent such as ammonium persulfate or sodium persulfate. By soaking, the monomer is oxidatively polymerized to form a conductive polymer. In addition, ammonium persulfate, sodium persulfate and the like used as oxidizing agents also act as dopant agents. ... Method for forming conductive polymer layer [A]
Alternatively, the wound capacitor element is impregnated with an aqueous solution of an oxidizing agent such as ammonium persulfate or sodium persulfate, dried to precipitate the oxidizing agent, and then conductive by oxidative polymerization such as pyrrole or aniline or a derivative thereof. The monomer is oxidatively polymerized by immersion in a monomer that becomes a conductive polymer to form a conductive polymer. In addition, ammonium persulfate, sodium persulfate and the like used as oxidizing agents also act as dopant agents. ... Method for forming conductive polymer layer [B]
Either one of the methods [A] and [B] for forming the conductive polymer layer may be adopted and repeated a plurality of times, or a combination of both may be repeated a plurality of times.

  Next, the capacitor element on which the conductive polymer layer is formed as described above is washed with water, dried in a drying furnace, and then impregnated with an electrolytic solution.

Finally, as shown in FIG. 2, the element 7 is housed in a bottomed cylindrical aluminum case 8, and a rubber packing 9 is attached to the opening, and after drawing and curling, the rated voltage A desired electrolytic capacitor is completed by performing an aging treatment at about 85 ° C. for about 1 hour while applying.

The conductive polymer is a compound obtained by p-type doping a polymer having a conjugated double bond with a dopant agent.
The polymer is a polymer of one or more monomers that form a conjugated double bond polymer. Examples of the monomer include the following compounds (1) to (4) having 2 to 30 or more carbon atoms.
(1) Aliphatic triple bond compounds; acetylene, 1,6-heptadiyne and the like;
(2) Aromatic conjugated compounds; benzene, naphthalene, anthracene, etc .;
(3) Heteroatom-containing conjugated compounds; heterocyclic compounds such as pyrrole, thiophene, furan, and ethylenedioxythiophene; non-heterocyclic compounds such as aniline, sulfonated aniline, and diphenyl sulfide.
(4) A compound in which an alkyl group having 1 to 20 carbon atoms (for example, methyl, ethyl, lauryl, stearyl group, etc.), an aryl group (phenyl, naphthyl group, etc.) or the like is substituted.
One or two or more of these monomers may be used. Of these, the heteroatom-containing conjugated compound (3) is preferable, and more preferable are a heterocyclic compound and aniline, and particularly preferable are pyrrole, thiophene, ethylenedioxythiophene, and aniline.
Preferable examples of the conductive polymer include at least one selected from the group consisting of polypyrrole, polythiophene, polyethylenedioxythiophene, and polyaniline.

  Usually, a conjugated double bond polymer is used by p-type doping with a dopant agent. Doping (or doping) is to increase the conductivity of the conjugated double bond polymer by causing charge transfer between the conjugated double bond polymer and the dopant agent. A dopant agent is an electron-accepting or electron-donating compound that imparts conductivity to a conjugated double bond polymer. For example, by p-type doping an electron-accepting dopant agent into a conjugated double bond polymer, carriers are generated by removing some of the electrons in the conjugated orbital π orbitals, thereby increasing conductivity.

In the present invention, examples of the dopant agent include electron-accepting compounds such as organic sulfonic acid, fluorocarboxylic acid, boron complex, and inorganic acid. Specific examples of the organic sulfonic acid, fluorocarboxylic acid and boron complex include those exemplified as the anionic acid of the electrolyte (B).
Specific examples of the inorganic acid include the following compounds.
SO ₃ , HNO ₃ , H ₂ SO ₄ , H ₂ S ₂ O ₈ , HF, HPF ₆ , HBF ₄ , HAsF ₆ , HSbF ₆ , HAlF ₄ , HTaF ₆ , HNbF ₆ , H ₂ SiF ₆ , HCl, HPCl _{6 , hBCl 4, HAsCl 6, HSbCl} 6, HAlCl 4, HTaCl 6, HNbCl 6, H 2 SiCl 6, HBr, HPBr 6, HBBr 4, HAsBr 6, HSbBr 6, HAlBr 4, HTaBr 6, HNbBr 6, H 2 SiBr ₆ , HClO ₄ etc.
One or two or more dopant agents may be used in combination.

Of these, preferred are methanesulfonic acid, t-butylsulfonic acid, pentanesulfonic acid, dodecylbenzenesulfonic acid, benzenesulfonic acid, p-toluenesulfonic acid, 4-ethylbenzenesulfonic acid, 4-butylbenzenesulfonic acid, 4-octylbenzenesulfonic acid, 2-naphthalenesulfonic acid, butylnaphthalenesulfonic acid, anthraquinone-2-sulfonic acid, di (2-ethylhexyl) sulfosuccinic acid, o-sulfobenzoic acid, perfluorobutanesulfonic acid, perfluoropentanesulfone Acid, trifluoroacetic acid, perfluorobutyric acid, borodisuccinate complex, borodiglycolate complex, H ₂ SO ₄ , H ₂ S ₂ O ₈ , HBF ₄ , HAlF ₄ , HBCl ₄ , HBBr ₄ , more preferably Is t-butylsulfone Acid, pentanesulfonic acid, p-toluenesulfonic acid, 4-butylbenzenesulfonic acid, 2-naphthalenesulfonic acid, butylnaphthalenesulfonic acid, anthraquinone-2-sulfonic acid, perfluorobutanesulfonic acid, perfluoropentanesulfonic acid. .

As the separator in the present invention, sheet-like insulators such as manila paper, kraft paper, cloth, nonwoven fabric or polymer film are usually used.

The anodized foil in the present invention is an electrode in which an oxide film is formed on the surface of an etched aluminum foil, and the cathode foil is an electrode of an etched aluminum foil.

The electrolytic solution of the present invention suppresses the deterioration of the increase in ESR caused by the dedoping phenomenon by setting the molar ratio of the acid component and the base component, which are electrolyte components, to an excess of acid.
The pH of the electrolytic solution of the present invention in which the molar ratio of the acid component and the base component, which are electrolyte components, is set to an acid excess is preferably 2 to 7, more preferably 4 to 7, and particularly preferably 5 to 7. The stock solution pH of the electrolytic solution is preferably 7 or less from the viewpoint of suppressing the dedoping phenomenon in which the dopant agent escapes from the p-type conductive polymer of the conductive polymer impregnated in the electrolytic solution. 2 or more is preferable from the viewpoint of corrosion due to dissolution.

The electrolyte solution preferably comprises an organic solvent and an electrolyte component (acid component and base component), and contains an acid component in the electrolyte component of the electrolyte solution in excess of the base component.
As a result, when a dedoping phenomenon in which the dopant agent escapes from the conductive polymer layer into the electrolyte solution, the anionized dopant agent in the electrolyte solution shows acidity, so that the acid in the electrolyte component of the electrolyte solution in advance. By reducing the pH value of the electrolyte solution in advance by making the component more acid than the base component, the pH value of the anionized dopant agent and the pH value of the surrounding electrolyte solution can be brought close to suppress the dedope phenomenon. Effect. Since it is possible to suppress the deterioration of the increase in ESR associated with the dedoping phenomenon of the conductive polymer layer, it is possible to extend the life of the electrolytic capacitor.

  In addition, in setting the molar ratio of the acid component and the base component, which are the electrolyte components of the electrolytic solution, to an excess of acid, as described above, a method of adding an acid after-treatment to a general electrolytic solution, or electrolysis A method in which an excess of acid is set in advance in the liquid production stage can be mentioned.

  Examples of the organic solvent for the electrolyte include alcohols (methanol, ethanol, propanol, butanol, cyclobutanol, cyclohexanol, ethylene glycol, propylene glycol, glycerin, methyl cellosolve, ethyl cellosolve, methoxypropylene glycol), aprotic organic solvents As ether type [ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, ethylene glycol monophenyl ether, tetrahydrofuran, 3-methyltetrahydrofuran, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, diethylene glycol Ethyl ether], amides [N-methylformamide, N, N-dimethylformamide, N-ethylformamide, N, N-diethylformamide, N-methylacetamide, N, N-dimethylacetamide, etc.], nitriles [acetonitrile, Propionitrile, butyronitrile, acrylonitrile, methacrylonitrile, benzonitrile], lactones (γ-butyrolactone, β-butyrolactone, α-valerolactone, γ-valerolactone, etc.), carbonates (ethylene carbonate, propion carbonate, butylene carbonate, Dimethyl carbonate, diethyl carbonate], sulfoxides [sulfolane, 3-methylsulfolane, dimethyl sulfoxide] and the like can be used. These organic solvents can be used alone or in combination.

  As the organic carboxylic acid of the acid component, aliphatic carboxylic acid: ([saturated carboxylic acid such as oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, speric acid, azelaic acid, sebacic acid, undencanic acid Acid, dodecanedioic acid, tridecanedioic acid, tetradecanedioic acid, pentadecanedioic acid, hexadecanedioic acid, methylmalonic acid, ethylmalonic acid, propylmalonic acid, butylmalonic acid, pentylmalonic acid, hexylmalonic acid, dimethylmalonic acid, Diethylmalonic acid, methylpropylmalonic acid, methylbutylmalonic acid, ethylpropylmalonic acid, dipropylmalonic acid, methylsuccinic acid, ethylsuccinic acid, 2,2-dimethylsuccinic acid, 2,3-dimethylsuccinic acid, 2-methylglutar Acid, 3-methylglutaric acid, 3-methyl-3-ethylgluta Acid 3,3-diethylglutaric acid, methylsuccinic acid, 2-methylglutaric acid, 3-methylglutaric acid, 3,3-dimethylglutaric acid, 3-methyladipic acid, 1,6-decanedicarboxylic acid, 5,6 -Decanedicarboxylic acid, formic acid, acetic acid, propionic acid, butyric acid, isobutyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, lauric acid, myristic acid, stearic acid, behenic acid, undencanic acid], Saturated carboxylic acids such as maleic acid, fumaric acid, itotanic acid, acrylic acid, methacrylic acid, oleic acid]), aromatic carboxylic acids: (eg phthalic acid, salicylic acid, isophthalic acid, terephthalic acid, trimellitic acid, pyromellitic acid Benzoic acid, resorcinic acid, cinnamic acid, naphthoic acid) and the like. Among these, thermal conductivity is high and thermal conductivity is preferable. Also stable, phthalic acid, trimellitic acid, pyromellitic acid, maleic acid, salicylic acid, benzoic acid, an organic acid such as resorcin acid.

  Examples of the basic component of the electrolyte include an amidinium cation and / or a guanidinium cation.

  The following are mentioned as an amidinium cation.

(1) Imidazolinium 1,2,3,4-tetramethylimidazolinium, 1,3,4-trimethyl-2-ethylimidazolinium, 1,3-dimethyl-2,4-diethylimidazolinium 1,2-dimethyl-3,4-diethylimidazolinium, 1-methyl-2,3,4-triethylimidazolinium, 1,2,3,4-tetraethylimidazolinium, 1,2,3- Trimethylimidazolinium, 1,3-dimethyl-2-ethylimidazolinium, 1-ethyl-2,3-dimethylimidazolinium, 1,2,3-triethylimidazolinium, 4-cyano-1,2, 3-trimethylimidazolinium, 3-cyanomethyl-1,2-dimethylimidazolinium, 2-cyanomethyl-1,3-dimethylimidazolinium, 4-acetyl- 1,2,3-trimethylimidazolinium, 3-acetylmethyl-1,2-dimethylimidazolinium, 4-methylcarbooxymethyl-1,2,3-trimethylimidazolinium, 3-methylcarbooxymethyl- 1,2-dimethylimidazolinium, 4-methoxy-1,2,3-trimethylimidazolinium, 3-methoxymethyl-1,2-dimethylimidazolinium, 4-formyl-1,2,3-trimethylimidazole Linium, 3-formylmethyl-1,2-dimethylimidazolinium, 3-hydroxyethyl-1,2-dimethylimidazolinium, 4-hydroxymethyl-1,2,3-trimethylimidazolinium, 2-hydroxy Ethyl-1,3-dimethylimidazolinium and the like.

(2) Imidazoliums 1,3-dimethylimidazolium, 1,3-diethylimidazolium, 1-ethyl-3-methylimidazolium, 1,2,3-trimethylimidazolium, 1,2,3,4- Tetramethylimidazolium, 1,3-dimethyl-2-ethylimidazolium, 1,2-dimethyl-3-ethyl-imidazolium, 1,2,3-triethylimidazolium, 1,2,3,4-tetraethylimidazolium Lithium, 1,3-dimethyl-2-phenylimidazolium, 1,3-dimethyl-2-benzylimidazolium, 1-benzyl-2,3-dimethyl-imidazolium, 4-cyano-1,2,3-trimethyl Imidazolium, 3-cyanomethyl-1,2-dimethylimidazolium, 2-cyanomethyl-1,3-dimethyl-imidazolium 4-acetyl-1,2,3-trimethylimidazolium, 3-acetylmethyl-1,2-dimethylimidazolium, 4-methylcarbooxymethyl-1,2,3-trimethylimidazolium, 3-methylcarbo Oxymethyl-1,2-dimethylimidazolium, 4-methoxy-1,2,3-trimethylimidazolium, 3-methoxymethyl-1,2-dimethylimidazolium, 4-formyl-1,2,3-trimethylimidazolium Rium, 3-formylmethyl-1,2-dimethylimidazolium, 3-hydroxyethyl-1,2-dimethylimidazolium, 4-hydroxymethyl-1,2,3-trimethylimidazolium, 2-hydroxyethyl-1, 3-dimethylimidazolium and the like.

(3) Tetrahydropyrimidinium 1,3-dimethyl-1,4,5,6-tetrahydropyrimidinium, 1,2,3-trimethyl-1,4,5,6-tetrahydropyrimidinium, 1, 2,3,4-tetramethyl-1,4,5,6-tetrahydropyrimidinium, 1,2,3,5-tetramethyl-1,4,5,6-tetrahydropyrimidinium, 8-methyl- 1,8-diazabicyclo [5,4,0] -7-undecenium, 5-methyl-1,5-diazabicyclo [4,3,0] -5-nonenium, 4-cyano-1,2,3-trimethyl- 1,4,5,6-tetrahydropyrimidinium, 3-cyanomethyl-1,2-dimethyl-1,4,5,6-tetrahydropyrimidinium, 2-cyanomethyl-1,3-dimethyl-1,4 5,6-tetra Hydropyrimidinium, 4-acetyl-1,2,3-trimethyl-1,4,5,6-tetrahydropyrimidinium, 3-acetylmethyl-1,2-dimethyl-1,4,5,6-tetrahydro Pyrimidinium, 4-methylcarbooxymethyl-1,2,3-trimethyl-1,4,5,6-tetrahydropyrimidinium, 3-methylcarbooxymethyl-1,2-dimethyl-1,4,5 , 6-tetrahydropyrimidinium, 4-methoxy-1,2,3-trimethyl-1,4,5,6-tetrahydropyrimidinium, 3-methoxymethyl-1,2-dimethyl-1,4,5, 6-tetrahydropyrimidinium, 4-formyl-1,2,3-trimethyl-1,4,5,6-tetrahydropyrimidinium, 3-formylmethyl-1,2-dimethyl-1,4 5,6-tetrahydropyrimidinium, 3-hydroxyethyl-1,2-dimethyl-1,4,5,6-tetrahydropyrimidinium, 4-hydroxymethyl-1,2,3-trimethyl-1,4 5,6-tetrahydropyrimidinium, 2-hydroxyethyl-1,3-dimethyl-1,4,5,6-tetrahydropyrimidinium and the like.

(4) Dihydropyrimidinium 1,3-dimethyl-1,4- or -1,6-dihydropyrimidinium [these are referred to as 1,3-dimethyl-1,4 (6) -dihydropyrimidinium The same expression is used hereinafter. 1,2,3-trimethyl-1,4 (6) -dihydropyrimidinium, 1,2,3,4-tetramethyl-1,4 (6) -dihydropyrimidinium, 1,2,3 5-tetramethyl-1,4 (6) -dihydropyrimidinium, 8-methyl-1,8-diazabicyclo [5,4,0] -7,9 (10) -undecadienium, 5-methyl- 1,5-diazabicyclo [4,3,0] -5,7 (8) -nonadienium, 4-cyano-1,2,3-trimethyl-1,4 (6) -dihydropyrimidinium, 3-cyanomethyl- 1,2-dimethyl-1,4 (6) -dihydropyrimidinium, 2-cyanomethyl-1,3-dimethyl-1,4 (6) -dihydropyrimidinium, 4-acetyl-1,2,3- Trimethyl-1,4 (6) -dihydropyrimidinium, 3 Acetylmethyl-1,2-dimethyl-1,4 (6) -dihydropyrimidinium, 4-methylcarbooxymethyl-1,2,3-trimethyl-1,4 (6) -dihydropyrimidinium, 3- Methylcarbooxymethyl-1,2-dimethyl-1,4 (6) -dihydropyrimidinium, 4-methoxy-1,2,3-trimethyl-1,4 (6) -dihydropyrimidinium, 3-methoxy Methyl-1,2-dimethyl-1,4 (6) -dihydropyrimidinium, 4-formyl-1,2,3-trimethyl-1,4 (6) -dihydropyrimidinium, 3-formylmethyl-1 , 2-Dimethyl-1,4 (6) -dihydropyrimidinium, 3-hydroxyethyl-1,2-dimethyl-1,4 (6) -dihydropyrimidinium, 4-hydroxymethyl-1,2,3 Trimethyl-1,4 (6) - dihydropyrimidinium, 1,3 2-hydroxyethyl dimethyl-1,4 (6) - such as hydro pyrimidinium.

  Examples of the guanidinium cation (C2) include the following.

(1) Guanidiniums having an imidazolinium skeleton 2-dimethylamino-1,3,4-trimethylimidazolinium, 2-diethylamino-1,3,4-trimethylimidazolinium, 2-diethylamino-1,3- Dimethyl-4-ethylimidazolinium, 2-dimethylamino-1-methyl-3,4-diethylimidazolinium, 2-diethylamino-1-methyl-3,4-diethylimidazolinium, 2-diethylamino-1, 3,4-tetraethylimidazolinium, 2-dimethylamino-1,3-dimethylimidazolinium, 2-diethylamino-1,3-dimethylimidazolinium, 2-dimethylamino-1-ethyl-3-methylimidazoli Ni, 2-diethylamino-1,3-diethylimidazolinium, 1,5,6,7 -Tetrahydro-1,2-dimethyl-2H-imide [1,2a] imidazolinium, 1,5-dihydro-1,2-dimethyl-2H-imide [1,2a] imidazolinium, 1,5,6 , 7-tetrahydro-1,2-dimethyl-2H-pyrimido [1,2a] imidazolinium, 1,5-dihydro-1,2-dimethyl-2H-pyrimido [1,2a] imidazolinium, 2-dimethyl Amino-4-cyano-1,3-dimethylimidazolinium, 2-dimethylamino-3-cyanomethyl-1-methylimidazolinium, 2-dimethylamino-4-acetyl-1,3-dimethylimidazolinium, 2 -Dimethylamino-3-acetylmethyl-1-methylimidazolinium, 2-dimethylamino-4-methylcarbooxymethyl-1,3-dimethylimidazole Linium, 2-dimethylamino-3-methylcarbooxymethyl-1-methylimidazolinium, 2-dimethylamino-4-methoxy-1,3-dimethylimidazolinium, 2-dimethylamino-3-methoxymethyl-1 -Methylimidazolinium, 2-dimethylamino-4-formyl-1,3-dimethylimidazolinium, 2-dimethylamino-3-formylmethyl-1-methylimidazolinium, 2-dimethylamino-3-hydroxyethyl -1-methylimidazolinium, 2-dimethylamino-4-hydroxymethyl-1,3-dimethylimidazolinium, and the like.

(2) Guanidiniums having an imidazolium skeleton 2-dimethylamino-1,3,4-trimethylimidazolium, 2-diethylamino-1,3,4-trimethylimidazolium, 2-diethylamino-1,3-dimethyl-4 -Ethylimidazolium, 2-dimethylamino-1-methyl-3,4-diethylimidazolium, 2-diethylamino-1-methyl-3,4-diethylimidazolium, 2-diethylamino-1,3,4-tetraethylimidazo Lithium, 2-dimethylamino-1,3-dimethylimidazolium, 2-diethylamino-1,3-dimethylimidazolium, 2-dimethylamino-1-ethyl-3-methylimidazolium, 2-diethylamino-1,3- Diethylimidazolium, 1,5,6,7-tetrahydro-1,2 -Dimethyl-2H-imide [1,2a] imidazolium, 1,5-dihydro-1,2-dimethyl-2H-imide [1,2a] imidazolium, 1,5,6,7-tetrahydro-1,2 -Dimethyl-2H-pyrimido [1,2a] imidazolium, 1,5-dihydro-1,2-dimethyl-2H-pyrimido [1,2a] imidazolium, 2-dimethylamino-4-cyano-1,3- Dimethylimidazolium, 2-dimethylamino-3-cyanomethyl-1-methylimidazolium, 2-dimethylamino-4-acetyl-1,3-dimethylimidazolinium, 2-dimethylamino-3-acetylmethyl-1-methyl Imidazolium, 2-dimethylamino-4-methylcarbooxymethyl-1,3-dimethylimidazolium, 2-dimethylamino-3-methyl Lucaloxymethyl-1-methylimidazolium, 2-dimethylamino-4-methoxy-1,3-dimethylimidazolium, 2-dimethylamino-3-methoxymethyl-1-methylimidazolium, 2-dimethylamino-4 -Formyl-1,3-dimethylimidazolium, 2-dimethylamino-3-formylmethyl-1-methylimidazolium, 2-dimethylamino-3-hydroxyethyl-1-methylimidazolium, 2-dimethylamino-4- Hydroxymethyl-1,3-dimethylimidazolium and the like.

(3) Guanidiniums having a tetrahydropyrimidinium skeleton 2-dimethylamino-1,3,4-trimethyl-1,4,5,6-tetrahydropyrimidinium, 2-diethylamino-1,3,4-trimethyl- 1,4,5,6-tetrahydropyrimidinium, 2-diethylamino-1,3-dimethyl-4-ethyl-1,4,5,6-tetrahydropyrimidinium, 2-dimethylamino-1-methyl-3 , 4-Diethyl-1,4,5,6-tetrahydropyrimidinium, 2-diethylamino-1-methyl-3,4-diethyl-1,4,5,6-tetrahydropyrimidinium, 2-diethylamino-1 , 3,4-tetraethyl-1,4,5,6-tetrahydropyrimidinium, 2-dimethylamino-1,3-dimethyl-1,4,5,6-teto Hydropyrimidinium, 2-diethylamino-1,3-dimethyl-1,4,5,6-tetrahydropyrimidinium, 2-dimethylamino-1-ethyl-3-methyl-1,4,5,6-tetrahydro Pyrimidinium, 2-diethylamino-1,3-diethyl-1,4,5,6-tetrahydropyrimidinium, 1,3,4,6,7,8-hexahydro-1,2-dimethyl-2H-imide [1,2a] pyrimidinium, 1,3,4,6-tetrahydro-1,2-dimethyl-2H-imide [1,2a] pyrimidinium, 1,3,4,6,7,8-hexahydro-1,2 -Dimethyl-2H-pyrimido [1,2a] pyrimidinium, 1,3,4,6-tetrahydro-1,2-dimethyl-2H-pyrimido [1,2a] pyrimidinium, 2-dimethylamino 4-cyano-1,3-dimethyl-1,4,5,6-tetrahydropyrimidinium, 2-dimethylamino-3-cyanomethyl-1-methyl-1,4,5,6-tetrahydropyrimidinium, 2-dimethylamino-4-acetyl-1,3-dimethyl-1,4,5,6-tetrahydropyrimidinium, 2-dimethylamino-3-acetylmethyl-1-methyl-1,4,5,6- Tetrahydropyrimidinium, 2-dimethylamino-4-methylcarbooxymethyl-1,3-dimethyl-1,4,5,6-tetrahydropyrimidinium, 2-dimethylamino-3-methylcarbooxymethyl-1- Methyl-1,4,5,6-tetrahydropyrimidinium, 2-dimethylamino-4-methoxy-1,3-dimethyl-1,4,5,6-tetrahydropyrimidi Dinium, 2-dimethylamino-3-methoxymethyl-1-methyl-1,4,5,6-tetrahydropyrimidinium, 2-dimethylamino-4-formyl-1,3-dimethyl-1,4,5 6-tetrahydropyrimidinium, 2-dimethylamino-3-formylmethyl-1-methyl-1,4,5,6-tetrahydropyrimidinium, 2-dimethylamino-3-hydroxyethyl-1-methyl-1, 4,5,6-tetrahydropyrimidinium, 2-dimethylamino-4-hydroxymethyl-1,3-dimethyl-1,4,5,6-tetrahydropyrimidinium and the like.

(4) Guanidiniums having a dihydropyrimidinium skeleton 2-dimethylamino-1,3,4-trimethyl-1,4 (6) -dihydropyrimidinium, 2-diethylamino-1,3,4-trimethyl-1 , 4 (6) -dihydropyrimidinium, 2-diethylamino-1,3-dimethyl-4-ethyl-1,4 (6) -dihydropyrimidinium, 2-dimethylamino-1-methyl-3,4- Diethyl-1,4 (6) -dihydropyrimidinium, 2-diethylamino-1-methyl-3,4-diethyl-1,4 (6) -dihydropyrimidinium, 2-diethylamino-1,3,4 Tetraethyl-1,4 (6) -dihydropyrimidinium, 2-dimethylamino-1,3-dimethyl-1,4 (6) -dihydropyrimidinium, 2-diethylamino-1 3-dimethyl-1,4 (6) -dihydropyrimidinium, 2-dimethylamino-1-ethyl-3-methyl-1,4 (6) -dihydropyrimidinium, 2-diethylamino-1,3-diethyl -1,4 (6) -dihydropyrimidinium, 1,6,7,8-tetrahydro-1,2-dimethyl-2H-imide [1,2a] pyrimidinium, 1,6-dihydro-1,2-dimethyl -2H-imide [1,2a] pyrimidinium, 1,6,7,8-tetrahydro-1,2-dimethyl-2H-pyrimido [1,2a] pyrimidinium, 1,6-dihydro-1,2-dimethyl-2H -Pyrimido [1,2a] pyrimidinium, 2-dimethylamino-4-cyano-1,3-dimethyl-1,4 (6) -dihydropyrimidinium, 2-dimethylamino-3-cyanomethy -1-methyl-1,4 (6) -dihydropyrimidinium, 2-dimethylamino-4-acetyl-1,3-dimethyl-1,4 (6) -dihydropyrimidinium, 2-dimethylamino-3 -Acetylmethyl-1-methyl-1,4 (6) -dihydropyrimidinium, 2-dimethylamino-4-methylcarbooxymethyl-1,3-dimethyl-1,4 (6) -dihydropyrimidinium, 2-Dimethylamino-3-methylcarbooxymethyl-1-methyl-1,4 (6) -dihydropyrimidinium, 2-dimethylamino-4-methoxy-1,3-dimethyl-1,4 (6)- Dihydropyrimidinium, 2-dimethylamino-3-methoxymethyl-1-methyl-1,4 (6) -dihydropyrimidinium, 2-dimethylamino-4-formyl-1,3-dimethyl 1,4,5,6-tetrahydropyrimidinium, 2-dimethylamino-3-formylmethyl-1-methyl-1,4,5,6-tetrahydropyrimidinium, 2-dimethylamino-3-hydroxy Ethyl-1-methyl-1,4,5,6-tetrahydropyrimidinium, 2-dimethylamino-4-hydroxymethyl-1,3-dimethyl-1,4 (6) -dihydropyrimidinium, and the like.

  The amidinium cation and guanidinium cation may be used alone or in combination of two or more.

Of these, preferred as amidinium cations are imidazoliniums, and particularly preferred are 1,2,3,4-tetramethylimidazolinium, 1,2,3-trimethylimidazolinium, 1-ethyl-2,3-dimethylimidazolinium.
Preferred as the guanidinium cation are guanidiniums having an imidazolinium skeleton, and particularly preferred are 2-dimethylamino-1,3,4-trimethylimidazolinium, 2-dimethylamino-1,3- Dimethylimidazolinium, 2-dimethylamino-1-ethyl-3-methylimidazolinium.

  An antioxidant can also be added to the electrolyte. As this antioxidant, there are phenol compounds, amine compounds, silane compounds, quinone compounds, carboxylic acid compounds, especially phenol, methylphenol, ethylphenol, pyrogallol, hydroquinone, pyrocatechol, tocophenol, butylhydroxyanisole, dibutylhydroxyl. By using an aromatic compound such as toluene, benzoic acid, salicylic acid, resorcinic acid, or benzotriazole, it is easy to resonance-stabilize electrons that contribute to oxidative degradation and improve the antioxidant effect. In connection with this, since the fall of the electrical conductivity of the electroconductive separator by oxidation deterioration can be suppressed, it is preferable as an antioxidant added in electrolyte solution.

  By adding an antioxidant into the electrolyte, the expected effect of the antioxidant is to suppress the oxidative deterioration of the conductive polymer layer and to suppress the increase in ESR with the passage of time of the electrolytic capacitor. In addition to this, in addition to this, it is possible to make the effect of the above-described electrolyte solution more prominent due to the excess of the acid component.

  Furthermore, an additive can also be added to the electrolytic solution. These additives include phosphorus compounds (such as phosphate esters), boric acid compounds (boric acid, complex compounds of boric acid and polysaccharides such as mannitol and sorbit), boric acid and polyhydric alcohols (ethylene Glycol, glycerin, etc.) and nitro compounds (o-nitrobenzoic acid, m-nitrobenzoic acid, p-nitrobenzoic acid, o-nitrophenol, m-nitrophenol, p-nitrophenol, etc.). . Adding these additives may increase the spark voltage of the electrolyte and may be preferable.

  In addition, an antioxidant is added to an acid-excess electrolytic solution to suppress oxidative deterioration of the conductive polymer layer and to suppress an increase in ESR over time of the electrolytic capacitor. In addition to this, it is possible to obtain the effect of the period, and in addition to this, the effect of setting the above-described electrolytic solution in excess of acid can be made more remarkable.

Example Using the electrolytic solutions of Examples 1 to 8 shown in Table 1, the ESR change in the high temperature test of the electrolytic capacitor shown in FIGS. 1 and 2 was measured. The results are shown in Table 1. ESR was measured with PRECISION LCR METER 4284A manufactured by HEWLETT PACKARD, and the measurement circuit used the AC bridge method. Measurement conditions are a frequency of 100 kH and a voltage of 0.5 Vrms. In the high-temperature test of the electrolytic capacitor, the ESR after assembling the electrolytic capacitor and the ESR after 1000 hours in a 6.3 V load test in an atmosphere of 105 ° C. were measured.

As is apparent from Table 1, by including an acid component in the electrolyte component of the driving electrolyte in excess of the base component, the ESR change in the high-temperature test of the electrolytic capacitor is significantly improved compared to the comparative example. It was. In particular, the electrolytic capacitors of Examples 7 to 8 to which an antioxidant is added are not clarified at present for the reason. However, the acid component and the antioxidant probably form a hydrogen bond as a result of the aromatic compound. This is considered to be based on the principle that the anti-oxidant is activated and the ability to suppress deterioration is increased.

  The electrolytic capacitor using the electrolytic solution for electrolytic capacitor according to the present invention can suppress the dedoping phenomenon and suppress an increase in ESR with the passage of time of the electrolytic capacitor, and is particularly useful as an electrolytic capacitor used in a high frequency region. is there.

It is a disassembled perspective view of the capacitor | condenser element used for this invention Example. It is sectional drawing of the electrolytic capacitor by this invention Example.

Explanation of symbols

1 Anodized foil 2 Opposite cathode foil 3 Separator 4 Winding tape 51 Anode lead wire 52 Cathode lead wire 61 Anode lead tab 62 Cathode lead tab 7 Capacitor element 8 Exterior case 9 Rubber packing

Claims (7)

A conductive polymer layer is formed in a capacitor element formed by winding an anodized foil and a counter cathode foil through a separator, and a gap between the conductive polymer layer is impregnated with an electrolytic solution. An electrolytic solution for an electrolytic capacitor used for an electrolytic capacitor, wherein the molar ratio of an acid component and a base component that are electrolyte components of the electrolytic solution is acid excess. Furthermore, the electrolyte solution of Claim 1 which added antioxidant. The electrolytic solution according to claim 1 or 2, having a pH of 2 to 7. The electrolyte solution according to any one of claims 1 to 3, wherein the acid component of the electrolyte is an organic carboxylic acid. The electrolyte solution according to any one of claims 1 to 4, wherein the basic component of the electrolyte is an amidinium cation and / or a guanidinium cation. The electrolytic solution according to claim 5, wherein the amidinium cation is an imidazolinium cation. The conductive polymer layer is formed in a capacitor element formed by winding the anodized foil and the counter cathode foil through a separator, and the gap between the conductive polymer layers is defined in any one of claims 1 to 6. An electrolytic capacitor, which is impregnated with the electrolytic solution described above.

Images