JP2007123818A - Electrolytic capacitor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an unconventionally miniaturized electrolytic capacitor. <P>SOLUTION: This electrolytic capacitor contains an electrolyte containing a tetrafluoride aluminum salt or an electrolyte added with a compound for generating phosphate ions in a solution using a solvent containing water in an aqueous solution and a chelating agent, in a capacitor element provided with an electrode material in which a valve metal particle layer having an oxide film on its surface is formed on the surface of a base material so that its porosity is 20-60% and a specific surface area is 20×10<SP>3</SP>to 400×10<SP>3</SP>cm<SP>2</SP>/cm<SP>3</SP>, wherein the valve metal particles of a particle size of at least a range of 0.005-0.1 μm are mixed with a predetermined distribution or the particles of a particle size of not less than 0.2 μm are contained. Thus, the electrolytic capacitor can be unconventionally miniaturized. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an electrolytic capacitor, and more particularly to an electrolytic capacitor that is miniaturized.

  An electrolytic capacitor is generally a strip-like high-purity aluminum foil that is chemically or electrochemically etched to enlarge the surface of the aluminum foil, and this aluminum foil is converted into a chemical conversion solution such as an aqueous solution of ammonium adipate. The electrode lead-out means is connected to the anode electrode foil formed with a chemical conversion treatment inside to form an oxide film layer on the surface, and the cathode electrode foil made of high-purity aluminum foil subjected only to the etching treatment, and made of manila paper or the like A capacitor element is formed by winding through a separator. Then, after impregnating the electrolytic solution for driving the electrolytic capacitor, this capacitor element is housed in a bottomed cylindrical outer case made of aluminum or the like. A sealing body made of elastic rubber is attached to the opening of the outer case, and the outer case is sealed by drawing.

  Here, as an electrolytic solution for driving an electrolytic capacitor having high conductivity impregnated in a capacitor element, γ-butyrolactone is a main solvent, and an imidazolinium cation or an imidazole which is a cation obtained by quaternizing a cyclic amidine compound as a solute. A solution in which a salt containing a cation component as a cation component and an acid conjugate base as an anion component is dissolved is used (see Patent Documents 1 and 2).

Further, in such an aluminum electrolytic capacitor, in order to increase the capacitance, the effective surface area of the etching foil is expanded to improve the capacitance per unit area, and the effective surface area of the etching foil is increased. Etching technology is being developed. As such an etching technique, the composition of an etching solution and the development of a current waveform applied during etching have been performed. (Patent Documents 3 and 4)
JP 08-32440 A Japanese Patent Application Laid-Open No. 08-324411 JP 2005-203529 A JP 2005-203530 A

  By the way, such an electrolytic capacitor is used in an electronic information device typified by a mobile phone or a notebook personal computer. However, due to the recent progress in downsizing and weight reduction of the electronic information device, the electrolytic capacitor is also used. Miniaturization is required.

  The demand for such miniaturization has been met by increasing the capacity of the electrode foil, but even if the electrode foil has been increased in capacity, the impedance has increased due to the reduction in the area of the electrode foil. There is a point. That is, in the electronic information device, there is also a demand for reduction of impedance characteristics, and miniaturization must be realized while maintaining the impedance characteristics, and it has been difficult to satisfy this demand.

Therefore, an object of the present invention is to provide an electrolytic capacitor that can be reduced in size without impairing impedance characteristics.

The first electrolytic capacitor of the present invention has a valve metal particle layer having an oxide film on the surface with a porosity of 20 to 60% and a specific surface area of 20 × 10 ^{3 to} 400 × 10 ³ cm ² / cm ³ on the surface of the substrate. The capacitor element including the formed electrode material contains an electrolytic solution containing an aluminum tetrafluoride salt.

The second electrolytic capacitor of the present invention has a valve metal particle layer having an oxide film on the surface with a porosity of 20 to 60% and a specific surface area of 20 × 10 ^{3 to} 400 × 10 ³ cm ² / cm ³ on the surface of the substrate. The capacitor element having the formed electrode material is characterized by containing an electrolyte solution containing a compound that generates phosphate ions in an aqueous solution using a solvent containing water and a chelating agent.

The electrode material used for the electrolytic capacitor of the present invention is a base material having a valve metal particle layer having an oxide film on the surface with a porosity of 20 to 60% and a specific surface area of 20 × 10 ^{3 to} 400 × 10 ³ cm ² / cm ^3. It has an electrostatic capacity several times that of a conventional electrode foil.

In such an electrode material for electrolytic capacitors of the present invention, the electrode material in which the valve metal particle layer is formed with a porosity of 20 to 60% and a specific surface area of 30 × 10 ^{3 to} 400 × 10 ³ cm ² / cm ³ is The primary particles of the valve metal particles are mixed with a predetermined distribution in a particle size range of at least 0.005 to 0.1 μm. Capacitance is increased by particles having a small particle size, and voids can be secured by particles having a large particle size, so that clogging due to an oxide film generated by reaction with an electrolytic solution can be suppressed after an electrolytic capacitor is created. . Therefore, an electrode material having a large capacitance can be obtained by increasing the number of particles having a small particle diameter, and the stability of the capacitance can be increased by increasing the number of particles having a large particle diameter.

  Moreover, the electrode material for electrolytic capacitors of the present invention has a valve metal made of aluminum, and a valve metal particle layer having an oxide film on the surface has an Al / O composition ratio of 2.0 to 5.5. Furthermore, the bonding property between the valve metal particles is improved by the oxygen content of this composition ratio.

Next, the electrode material formed on the surface of the substrate with a valve metal particle layer having an oxide film on the surface having a porosity of 20 to 60% and a specific surface area of 20 × 10 ³ to 70 × 10 ³ cm ² / cm ³ is Since the valve metal particles include those having a particle diameter of 0.2 μm or more in the metal particle layer, a large gap can be provided between the valve metal particles. Therefore, when an anodic oxide film is formed by anodization, it is suppressed that the void is filled with the oxide film, and a high capacitance can be obtained.

  In the electrode material for electrolytic capacitors of the present invention, the valve metal is aluminum, and the Al / O composition ratio of the valve metal particle layer having an oxide film on the surface is 2.0 to 125. Furthermore, the bonding property between the valve metal particles is improved by the oxygen content of this composition ratio.

  The first electrolytic capacitor of the present invention using the above-mentioned electrode material of the present invention and the low specific resistance electrolytic solution containing aluminum tetrafluoride has good electrochemical stability between the electrode material and the electrolytic solution. Since the electrode material has a high capacitance, the foil area can be reduced and the size can be reduced. In addition, the use of an electrolyte with a low specific resistance does not impair the impedance characteristics, and it is an unprecedented size The electrolytic capacitor can be realized.

  Further, the second electrolysis of the present invention using a low specific resistance electrolytic solution including a compound that generates phosphate ions in an aqueous solution and an electrolytic solution to which a chelating agent is added using a solvent containing the electrode material of the present invention and water. Capacitors have good electrochemical stability between the electrode material and the electrolyte, and since the electrode material has a high capacitance, the foil area can be reduced and the size can be reduced. Since the liquid is used, impedance characteristics are not impaired, and an unprecedented small electrolytic capacitor can be realized.

Electrode capacitor electrode material used in the present invention is an electrode material having a valve metal particle layer having an oxide film on the surface, the porosity of the valve metal particle layer is 20 to 60%, preferably 25 to 55%, More preferably, it is 30 to 50%. The specific surface area is 30 × 10 ^{3 to} 400 × 10 ³ cm ² / cm ³ , preferably 70 × 10 ^{3 to} 400 × 10 ³ cm ² / cm ³ , more preferably 90 × 10 ^{3 to} 400 × 10 ^3. cm ² / cm ³ .

  The specific surface area is calculated from the capacitance and area of a plain foil on which a film having capacitance is formed on the electrode material of the present invention, and a similar film is formed. The porosity can be measured by a mercury intrusion method.

  In the electrode material, primary particles of the valve metal particles are mixed with a predetermined distribution within a particle diameter range of at least 0.005 to 0.1 μm. High capacitance can be obtained by such small particles, and voids can be secured by the large particles, so that clogging due to an oxide film generated by reaction with the electrolytic solution after the electrolytic capacitor is formed can be suppressed. Therefore, an electrode material having a large capacitance can be obtained by increasing the number of particles having a small particle diameter, and the stability of the capacitance can be increased by increasing the number of particles having a large particle diameter.

  In the electrode material, the valve metal is aluminum, and the Al / O composition ratio of the valve metal particle layer having an oxide film on the surface is 2.0 to 5.5. The Al / O composition ratio can be measured and calculated by GDS analysis.

  The electrode material is preferably used as a cathode, but may be subjected to cathodic conversion. Furthermore, it can also be used as an anode material for electrolytic capacitors by performing anodization at an extremely low pressure. As a chemical conversion method, a chemical conversion method similar to that of an aluminum foil for electrolytic capacitors can be used.

Next, the electrode material for electrolytic capacitors of the present invention is an electrode material having a valve metal particle layer having an oxide film on the surface, and the porosity of the valve metal particle layer is 20 to 60%, preferably 22 to 58. %, More preferably 25-55%. The specific surface area is 20 × 10 ³ to 70 × 10 ³ cm ² / cm ³ , preferably 30 × 10 ^{3 to} 60 × 10 ³ cm ² / cm ³ , more preferably 35 × 10 ^{3 to} 55 × 10 ^3. cm ² / cm ³ .

  Further, since the electrode material includes valve metal particles having an oxide film on the surface having a particle diameter of 0.2 μm or more in the valve metal particle layer, a large gap can be provided between the valve metal particles. Therefore, when an anodic oxide film is formed by anodization, it is suppressed that the void is filled with the oxide film, and a high capacitance can be obtained.

  In addition, the electrode material, the valve metal is aluminum, and the Al / O composition ratio of the valve metal particle layer having an oxide film on the surface is 2.0 to 125, so that the capacitance can be stable, Furthermore, the bondability between the valve metal particles is improved by the oxygen content of this composition ratio.

  The electrode material is preferably used as an anode material for electrolytic capacitors by anodizing. As a chemical conversion method, a chemical conversion method similar to that of an aluminum foil for electrolytic capacitors can be used.

  As the substrate, various metals and, in some cases, resin sheets can be used, but aluminum is preferable. The purity of aluminum is preferably 99 wt% to 99.999 wt%. The thickness of the substrate is preferably 15 to 200 μm.

  The electrode material as described above can be obtained by a normal vapor deposition method. In order to form a valve metal particle layer having an oxide film on the surface, vapor deposition is performed in an inert gas atmosphere containing oxygen. Argon, nitrogen, etc. can be used as the inert gas. The pressure of the inert gas is preferably 0.05 to 0.8 Pa, and the oxygen partial pressure is preferably 1/10 or less of the pressure of the inert gas.

  The first electrolytic capacitor of the present invention will be described below.

  The electrolytic solution used in the present invention contains an aluminum tetrafluoride salt, and the aluminum tetrafluoride salt is a salt containing aluminum tetrafluoride as an anionic component. As this salt, an ammonium salt, an amine salt, a quaternary ammonium salt, or a salt containing a quaternized cyclic amidinium ion as a cation component can be used.

  As amines constituting the amine salt, primary amines (methylamine, ethylamine, propylamine, butylamine, ethylenediamine, monoethanolamine, etc.), secondary amines (dimethylamine, diethylamine, dipropylamine, ethylmethylamine, diphenylamine, diethanolamine) Etc.) and tertiary amines (trimethylamine, triethylamine, tributylamine, triethanolamine, etc.). The quaternary ammonium constituting the quaternary ammonium salt includes tetraalkylammonium (tetramethylammonium, tetraethylammonium, tetrapropylammonium, tetrabutylammonium, methyltriethylammonium, dimethyldiethylammonium, etc.), pyridium (1-methyl Pyridium, 1-ethylpyridium, 1,3-diethylpyridium, etc.).

  Further, in a salt containing a quaternized cyclic amidinium ion as a cation component, the quaternized cyclic amidinium ion serving as a cation component quaternizes a cyclic compound having an N, N, N ′,-substituted amidine group. Examples of the cyclic compound having an N, N, N′-substituted amidine group include the following compounds. Imidazole monocyclic compounds (1-methylimidazole, 1-phenylimidazole, 1,2-dimethylimidazole, 1-ethyl-2-methylimidazole, 2-ethyl-1-methylimidazole, 1,2-diethylimidazole, 1,2 Imidazole homologues such as 1,4-trimethylimidazole, oxyalkyl derivatives such as 1-methyl-2-oxymethylimidazole, 1-methyl-2-oxyethylimidazole, nitro such as 1-methyl-4 (5) -nitroimidazole Derivatives, amino derivatives such as 1,2-dimethyl-5 (4) -aminoimidazole), benzoimidazole compounds (1-methylbenzimidazole, 1-methyl-2-benzylbenzimidazole, 1-methyl-5 (6 ) -Nitrobenzimidazole, etc.), 2-imidazoline (1-methylimidazoline, 1,2-dimethylimidazoline, 1,2,4-trimethylimidazoline, 1-methyl-2-phenylimidazoline, 1-ethyl-2-methylimidazoline, 1,4-dimethyl-2 -Ethyl imidazoline, 1-methyl-2-ethoxymethyl imidazoline, etc.), compounds having a tetrahydropyrimidine ring (1-methyl-1,4,5,6-tetrahydropyrimidine, 1,2-dimethyl-1,4,5, 6-tetrahydropyrimidine, 1,5-diazabicyclo [4,3,0] nonene-5, 1,8-diazabicyclo (5,4,0) -undecene-7, etc.).

  As the solvent used in the electrolytic solution of the present invention, a protic polar solvent, an aprotic solvent, and a mixture thereof can be used. Protic polar solvents include monohydric alcohols (ethanol, propanol, butanol, pentanol, hexanol, cyclobutanol, cyclopentanol, cyclohexanol, benzyl alcohol, etc.), polyhydric alcohols and oxyalcohol compounds (ethylene glycol) Propylene glycol, glycerin, methyl cellosolve, ethyl cellosolve, methoxypropylene glycol, dimethoxypropanol, etc.). Examples of aprotic polar solvents include amides (N-methylformamide, N, N-dimethylformamide, N-ethylformamide, N, N-diethylformamide, N-methylacetamide, N, N-dimethylacetamide, N-ethylacetamide, N, N-diethylacetamide, hexamethylphosphoricamide, etc.), lactones (γ-butyrolactone, δ-valerolactone, γ-valerolactone, etc.), sulfolanes (sulfolane, 3-methylsulfolane, 2 , 4-dimethylsulfolane, etc.), cyclic amides (N-methyl-2-pyrrolidone, etc.), carbonates (ethylene carbonate, propylene carbonate, isobutylene carbonate, etc.), nitriles (acetonitrile, etc.), sulfoxides (dimethylsulfoxide, etc.) , -Imidazolidinone series [1,3-dialkyl-2-imidazolidinone (1,3-dimethyl-2-imidazolidinone, 1,3-diethyl-2-imidazolidinone, 1,3-di (n-propyl ) -2-imidazolidinone, etc.), 1,3,4-trialkyl-2-imidazolidinone (1,3,4-trimethyl-2-imidazolidinone, etc.)] and the like. Among them, use of γ-butyrolactone is preferable because impedance characteristics are improved, and sulfolane, 3-methylsulfolane, and 2,4-dimethylsulfolane are preferable because high temperature characteristics are improved. Use of ethylene glycol improves withstand voltage characteristics. This is preferable.

  The solvent of the electrolytic solution for electrolytic capacitors of the present invention is preferably contained in an amount of 60 to 95 wt% from the viewpoint of obtaining an electrolytic solution having further excellent electrical conductivity, thermal stability, and voltage resistance.

  In the present invention using the above electrode material and electrolytic solution, since the electrode material has a high capacitance, the foil area can be reduced while having the same capacitance as the conventional one, and the electrolytic capacitor can be reduced in size. Can be planned. In addition, since the low specific resistance electrolytic solution is used and the impedance does not increase, a small electrolytic capacitor having the same capacitance as the conventional one can be realized.

Further, an insulating layer such as a ceramic coating layer made of Al ₂ O ₃ , SiO ₂ , ZrO ₂ or the like is formed on the surface of at least the contact portion of the cathode extraction means with the sealing rubber, or an ammonium borate aqueous solution, phosphoric acid An aluminum oxide layer formed by anodizing with an aqueous ammonium solution or an aqueous ammonium adipate solution can be formed.

    In the electrolytic capacitor of the present invention, the electrode material used as the cathode is a metal nitride selected from titanium nitride, zirconium nitride, tantalum nitride, niobium nitride, or a metal selected from titanium, zirconium, tantalum, niobium. Can be coated.

  The second electrolytic capacitor of the present invention will be described below.

    The electrolytic solution used in the present invention is obtained by adding a compound that generates phosphate ions in an aqueous solution and a chelating agent using a solvent containing water as a main component, the details of which are shown below.

  The electrolytic solution used in the present invention uses a solvent containing water as a main component, but the content of water is usually 35 to 100 wt%, preferably 35 to 65 wt%, more preferably 40 to 65 wt% of the entire solvent. It is. Below this range, the conductivity decreases.

  As the solvent, in addition to water, a protic polar solvent, an aprotic solvent, and a mixture thereof can be used. Protic polar solvents include monohydric alcohols (methanol, ethanol, propanol, butanol, hexanol, cyclohexanol, cyclopentanol, benzyl alcohol, etc.), polyhydric alcohols and oxyalcohol compounds (ethylene glycol, propylene glycol, glycerin). Methyl cellosolve, ethyl cellosolve, 1,3-butanediol, methoxypropylene glycol, etc.). Examples of aprotic solvents include amides (N-methylformamide, N, N-dimethylformamide, N-ethylformamide, N, N-diethylformamide, N-methylacetamide, hexamethylphosphoric amide, etc.), lactones, Typical examples include cyclic amides, carbonates (γ-butyrolactone, N-methyl-2-pyrrolidone, ethylene carbonate, propylene carbonate, etc.), nitriles (acetonitrile) oxides (dimethyl sulfoxide, etc.), and the like.

  And as a compound (phosphate ion generating compound) which produces | generates a phosphate ion in aqueous solution, the following compounds can be mentioned. The following are phosphorus compounds, phosphoric acid, phosphorous acid, hypophosphorous acid or salts thereof, and condensates or salts of these condensates.

  Examples of the phosphorus compounds or salts thereof include alkyl phosphates such as ethyl phosphate, diethyl phosphate, butyl phosphate, and dibutyl phosphate; phosphonic acid, 1-hydroxyethylidene-1,1-diphosphonic acid, aminotri And esters or derivatives of phosphonic acid or diphosphonic acid such as methylenephosphonic acid, phenylphosphonic acid; or phosphinic acid esters such as methylphosphinic acid, butyl phosphinate; and all salts thereof. Of these, dibutyl phosphate, 1-hydroxyethylidene-1,1-diphosphonic acid, or salts thereof are preferred. As salts of these phosphorus compounds, ammonium salts, aluminum salts, sodium salts, potassium salts, calcium salts and the like can be used.

  Further, condensed phosphoric acid which is a condensate of phosphoric acid or a salt thereof is used. Examples of the condensed phosphoric acid include linear condensed phosphoric acids such as pyrophosphoric acid, tripolyphosphoric acid and tetrapolyphosphoric acid, cyclic condensed phosphoric acids such as metaphosphoric acid and hexametaphosphoric acid, or such chain and cyclic condensed phosphoric acids. An acid bonded one can be used. And as a salt of these condensed phosphoric acids, ammonium salt, sodium salt, potassium salt, etc. can be used. Of these, pyrophosphoric acid, tripolyphosphoric acid, tetrapolyphosphoric acid and salts thereof are preferred, pyrophosphoric acid, tripolyphosphoric acid and salts thereof are more preferred, and tripolyphosphoric acid is most preferred. . As the salts of these condensates, ammonium salts, aluminum salts, sodium salts, potassium salts, calcium salts and the like can be used. Furthermore, phosphoric acid, phosphorous acid, hypophosphorous acid, and salts thereof can be used as the phosphate ion generating compound. These salts are ammonium, aluminum, sodium, calcium, and potassium salts. Phosphoric acid and its salts decompose in water to produce phosphate ions. In addition, phosphorous acid, hypophosphorous acid, and salts thereof are decomposed in an aqueous solution to form phosphite ions and hypophosphite ions, and then are oxidized to phosphate ions.

  And as a condensate other than the above condensed phosphoric acid, the above phosphorus compound, phosphorous acid, hypophosphorous acid, or a salt thereof, or these phosphorus compounds, phosphoric acid, phosphorous acid, hypophosphorous acid A salt condensate can be used. Furthermore, salts of these condensates can also be used. As the salt of the condensate, ammonium salt, aluminum salt, sodium salt, potassium salt, calcium salt and the like can be used.

  These are also phosphate ion-forming compounds that generate phosphate ions in an aqueous solution, or generate phosphite ions and hypophosphite ions, which are then oxidized to phosphate ions.

  Among these, phosphoric acid or a salt thereof that easily generates a phosphate ion, condensed phosphoric acid, or a derivative of phosphoric acid, for example, an ester of phosphoric acid or alkyl phosphoric acid is preferable. Furthermore, linear condensed phosphoric acid such as phosphoric acid, pyrophosphoric acid, tripolyphosphoric acid, or a salt thereof, which generates a large amount of phosphate ions relatively quickly with respect to the amount added, or a salt thereof is also preferable. In addition, the effect of the present invention can be obtained as long as it is a substance that generates phosphate ions in an aqueous solution other than these phosphate ion generating compounds.

  And the addition amount of these phosphate ion production | generation compounds is 0.01-3.0 wt% of the whole electrolyte solution, Preferably, it is 0.2-2.0 wt%. Outside this range, the effect is reduced.

  And as a chelating agent, the following are mentioned. That is, citric acid, tartaric acid, gluconic acid, malic acid, lactic acid, glycolic acid, α-hydroxybutyric acid, hydroxymalonic acid, α-methylphosphoric acid, α-hydroxycarboxylic acids such as dihydroxytartaric acid, γ-resorcylic acid, β- Resorcylic acid, trihydroxybenzoic acid, hydroxyphthalic acid, dihydroxyphthalic acid, phenol tricarboxylic acid, aluminone, aromatic hydroxycarboxylic acids such as eriochrome cyanine R, sulfocarboxylic acids such as sulfosalicylic acid, tannins such as tannic acid, dicyandiamide Guanidines such as galactose, saccharides such as glucose, lignins such as lignosulfonate, and ethylenediaminetetraacetic acid (EDTA), nitrilotriacetic acid (NTA), glycol etherdiaminetetraacetic acid (GEDTA), and diethyl Ntoriamin pentaacetic acid (DTPA), hydroxyethyl acid (HEDTA), an amino polycarboxylic acids, and their salts such as triethylenetetraminehexaacetic acid (TTHA). As these salts, ammonium salts, aluminum salts, sodium salts, potassium salts and the like can be used. Of these, preferred are tannic acid, trihydroxybenzoic acid, citric acid, tartaric acid, gluconic acid, aurin tricarboxylic acid, γ-resorcylic acid, DTPA, EDTA, GEDTA, HEDTA, TTHA, which easily chelate with aluminum. These salts are tannic acid, trihydroxybenzoic acid, citric acid, tartaric acid, γ-resorcylic acid and aurin tricarboxylic acid, DTPA, GEDTA, HEDTA, TTHA, or salts thereof.

  And the addition amount of these chelating agents is 0.01-3.0 wt% of the whole electrolyte solution, Preferably, it is 0.1-2.0 wt%. Outside this range, the effect is reduced.

  Moreover, as a solute of the electrolytic solution for an aluminum electrolytic capacitor used in the present invention, an ammonium salt, a quaternary ammonium salt, or an amine salt of a carboxylic acid such as adipic acid, formic acid, or benzoic acid can be used. The quaternary ammonium constituting the quaternary ammonium salt includes tetraalkylammonium (tetramethylammonium, tetraethylammonium, tetrapropylammonium, tetrabutylammonium, methyltriethylammonium, dimethyldiethylammonium, etc.), pyridium (1-methylpyridium). 1-ethylpyridium, 1,3-diethylpyridium, etc.). In addition, amines constituting the amine salt include primary amines (methylamine, ethylamine, propylamine, butylamine, ethylenediamine, monoethanolamine, etc.), secondary amines (dimethylamine, diethylamine, dipropylamine, ethylmethylamine, diphenylamine). , Diethanolamine, etc.) and tertiary amines (trimethylamine, triethylamine, tributylamine, 1,8-diazabicyclo (5,4,0) -undecene-7, triethanolamine, etc.).

  Furthermore, the following acids can also be used as the carboxylic acid. Decanedicarboxylic acids such as glutaric acid, succinic acid, isophthalic acid, phthalic acid, terephthalic acid, maleic acid, toluic acid, enanthic acid, malonic acid, 1,6-decanedicarboxylic acid, 5,6-decanedicarboxylic acid, It is a carboxylic acid such as octane dicarboxylic acid such as 7-octane dicarboxylic acid, azelaic acid or sebacic acid. In addition, boric acid, a polyhydric alcohol complex compound of boric acid obtained from boric acid and a polyhydric alcohol, and inorganic acids such as phosphoric acid, carbonic acid, and silicic acid can also be used. Among these, decanedicarboxylic acid, octanedicarboxylic acid, azelaic acid, sebacic acid, adipic acid, glutaric acid, succinic acid, benzoic acid, isophthalic acid, formic acid and other organic carboxylic acids, or boric acid and boric acid are preferred. It is a polyhydric alcohol complex compound. A salt containing a quaternized cyclic amidinium ion as a cation component can also be used. Examples of the acid serving as the anion component of this salt include phthalic acid, isophthalic acid, terephthalic acid, maleic acid, benzoic acid, toluic acid, enanthic acid, malonic acid, and the like.

  The quaternized cyclic amidinium ion serving as a cation component is a cation obtained by quaternizing a cyclic compound having an N, N, N′-substituted amidine group, and has an N, N, N′-substituted amidine group. Examples of the cyclic compound include the following compounds. Imidazole monocyclic compounds (1-methylimidazole, 1-phenylimidazole, 1,2-dimethylimidazole, 1-ethyl-2-methylimidazole, 1,2-dimethylimidazole, 1-ethyl-2-methylimidazole, 1,2 Imidazole homologues such as dimethylimidazole and 1,2,4-trimethylimidazole, oxyalkyl derivatives such as 1-methyl-2-oxymethylimidazole and 1-methyl-2-oxyethylimidazole, 1-methyl-4 (5 ) -Nitroimidazole and other nitro derivatives, 1,2-dimethyl-5 (4) -aminoimidazole and other amino derivatives), benzimidazole compounds (1-methylbenzimidazole, 1-methyl-2-benzimidazole, 1- Methyl-5 (6) -nitrobenzimidazole ), A compound having a 2-imidazoline ring (1-methylimidazoline, 1,2-dimethylimidazoline, 1,2,4-trimethylimidazoline, 1-methyl-2-phenylimidazoline, 1-ethyl-2-methyl-imidazoline, 1,4-dimethyl-2-ethylimidazoline, 1-methyl-2-ethoxymethylimidazoline, etc.), compounds having a tetrahydropyrimidine ring (1-methyl-1,4,5,6-tetrahydropyrimidine, 1,2-dimethyl) -1,4,5,6-tetrahydropyrimidine, 1,5-diazabicyclo [4,3,0] nonene-5, etc.).

  In the present invention using the above electrode material and electrolytic solution, since the electrode material has a high capacitance, the foil area can be reduced while having the same capacitance as the conventional one, and the electrolytic capacitor can be reduced in size. Can be planned. In addition, since the low specific resistance electrolyte is used and the impedance does not increase, a small electrolytic capacitor having the same capacitance as the conventional one can be realized.

The present invention will be described more specifically with reference to the following examples.
Example 1-1 Electrode of the present invention by depositing aluminum on a 25 μm 99.9 wt% aluminum sheet in an oxygen atmosphere at a pressure of 1/10 or less of nitrogen at a pressure of 0.1 Pa and nitrogen Made the material. The porosity of the metal particle layer of this electrode material was 45%, and the specific surface area was 2 × 10 ⁵ cm ² / cm ³ . A titanium nitride layer is formed on the surface of this electrode material and used as a cathode material.
Example 1-2 Electrode of the present invention by depositing aluminum on a 25 μm 99.9 wt% aluminum sheet in an oxygen atmosphere at a pressure of 1/10 or less of the pressure of nitrogen and the pressure of 0.3 Pa Made the material. The porosity of the metal particle layer of this electrode material was 45%, and the specific surface area was 5 × 10 ⁴ cm ² / cm ³ . Thereafter, anodization was performed in an aqueous solution of ammonium adipate to prepare an anode material.
(Comparative Example 1-1) Using a mixed solution of hydrochloric acid, sulfuric acid and nitric acid as an electrolyte, an alternating current having a frequency of 50 Hz or less and a current density of 1 A / cm ² or less was applied to a 99.9 wt% aluminum sheet. A cathode foil was prepared by performing an etching process so that the thickness was 25 μm, and a titanium nitride layer was formed on the surface.
(Comparative Example 1-2) Using a mixed solution of hydrochloric acid, sulfuric acid, and nitric acid as an electrolyte, an alternating current having a frequency of 20 Hz or less and a current density of 1 A / cm ² or less was applied to an aluminum sheet having a core thickness of 99.9 wt%. Was etched to 25 μm, and then formed in an aqueous solution of ammonium adipate to prepare an anode foil.

    In the first electrolytic capacitor of the present invention, electrode lead means are connected to these electrode materials and wound through a separator to form a capacitor element. Here, the ceramic coating layer was formed in the contact part with the sealing rubber of an electrode extraction means.

    The capacitor element configured as described above is impregnated with an electrolytic solution for driving an aluminum electrolytic capacitor. The capacitor element impregnated with this electrolytic solution is housed in an outer case made of bottomed cylindrical aluminum, a butyl rubber sealing body is inserted into the opening end of the outer case, and the end of the outer case is drawn. By doing so, the aluminum electrolytic capacitor is sealed.

    The electrolytic solution was composed of 55 parts of γ-butyrolactone and 35 parts of aluminum tetrafluoride in the examples, 75 parts of γ-butyrolactone and 25 parts of 1-ethyl-2,3-dimethylimidazolinium phthalate in the comparative example. The thing of was used.

  The initial values of these electrolytic capacitors and the results of the 105 ° C. load test are shown in Table 1.

    As described above, the first and second embodiments of the present invention are smaller in size while maintaining the characteristics of both capacitance and impedance as compared with the comparative example. Furthermore, Example 2 using the electrode material of the present invention for the anode has a large capacitance. As described above, it can be seen that the electrolytic capacitor of the present invention achieves miniaturization while maintaining the conventional capacitance and impedance.

      Next, the second electrolytic capacitor is connected to the above electrode material with an electrode drawing means and wound through a separator to form a capacitor element.

    The capacitor element configured as described above is impregnated with an electrolytic solution for driving an aluminum electrolytic capacitor. The capacitor element impregnated with this electrolytic solution is housed in an outer case made of bottomed cylindrical aluminum, a butyl rubber sealing body is inserted into the opening end of the outer case, and the end of the outer case is drawn. By doing so, the aluminum electrolytic capacitor is sealed.

    The electrolyte used in the examples was 40 parts of water, 50 parts of ethylene glycol, 8 parts of adipic acid, 1 part of diethylenetriaminepentaacetic acid, 1 part of ammonium dihydrogen phosphate, and pH adjusted with ammonia gas. A comparative example having a composition of 75 parts of γ-butyrolactone and 25 parts of 1-ethyl-2,3-dimethylimidazolinium phthalate was used.

  The initial values of these electrolytic capacitors and the results of the 105 ° C. load test are shown in (Table 2).

    As described above, the first and second embodiments of the present invention are smaller in size while maintaining the characteristics of both capacitance and impedance as compared with the comparative example. Furthermore, Example 2 using the electrode material of the present invention for the anode has a large capacitance. As described above, it can be seen that the electrolytic capacitor of the present invention achieves miniaturization while maintaining the conventional capacitance and impedance.

Claims (5)

In a capacitor element having an electrode material formed on the surface of a base material with a valve metal particle layer having an oxide film on the surface having a porosity of 20 to 60% and a specific surface area of 20 × 10 ^{3 to} 400 × 10 ³ cm ² / cm ³ An electrolytic capacitor containing an electrolytic solution containing an aluminum tetrafluoride salt. In a capacitor element having an electrode material formed on the surface of a base material with a valve metal particle layer having an oxide film on the surface having a porosity of 20 to 60% and a specific surface area of 20 × 10 ^{3 to} 400 × 10 ³ cm ² / cm ³ An electrolytic capacitor containing an electrolytic solution to which a compound that generates phosphate ions in an aqueous solution using a solvent containing water and a chelating agent are added. The electrolytic capacitor according to claim 1, wherein the valve metal particles are mixed with a predetermined distribution in a particle diameter range of at least 0.005 to 0.1 μm. The electrolytic capacitor according to claim 1, wherein the valve metal particles include those having a particle diameter of 0.2 μm or more. The electrolytic capacitor according to claim 1, wherein the valve metal is aluminum, and the Al / O composition ratio of the valve metal particle layer having an oxide film on the surface is 2.0 to 125.