KR102337435B1 - Electrolytic capacitor and manufacturing method thereof - Google Patents

Abstract

An electrolytic capacitor having a negative electrode exhibiting high capacity is provided. A conductive base, a cathode having a conductive polymer layer provided on a surface of the conductive base, a base made of a valve metal, and a dielectric layer comprising an oxide of the valve metal provided on the surface of the base, wherein the dielectric layer and the cathode are conductive An electrolytic capacitor comprising an anode in which polymer layers are disposed to face each other and an ion conductive electrolyte filled in the space, wherein the electrolytic capacitor is in contact with the ion conductive electrolyte by applying a voltage between the anode and the cathode It is an electrolytic capacitor characterized by the conductive polymer layer of a negative electrode expressing redox capacity.

Description

Electrolytic capacitor and manufacturing method thereof

The present invention relates to an electrolytic capacitor having a negative electrode exhibiting high capacity and a method for manufacturing the same.

An electrolytic capacitor having an ion-conducting electrolyte (including electrolyte) is generally an anode in which an oxide film as a dielectric layer is provided on the surface of a valve metal foil such as aluminum, tantalum, niobium, etc. negative electrode) and a separator holding an ion conductive electrolyte as a true negative electrode disposed between the positive electrode and the negative electrode are accommodated in a sealed case, and those of a wound type, stacked type, etc. are widely used.

This electrolytic capacitor has the advantage of being small and having a large capacity compared to a plastic capacitor, a mica capacitor, etc., and by thickening the oxide film of the anode, the breakdown voltage of the capacitor can be improved. However, if the oxide film of the anode is thickened, the capacity of the electrolytic capacitor is lowered, and some of the advantages of small size and large capacity are lost. Therefore, various studies have been made for the purpose of improving the capacity without lowering the breakdown voltage of the electrolytic capacitor, for example, chemical or electrochemical etching treatment on the valve metal foil constituting the anode and cathode It has been studied to effectively increase the surface area of these valve metal foils by controlling the conditions for that, thereby increasing the capacity of not only the positive electrode but also the negative electrode.

In addition, in Patent Document 1 (Japanese Patent Publication No. 3-37293), in an aluminum electrolytic capacitor, if the etching is excessive, the dissolution of the surface of the aluminum foil into the etching solution proceeds at the same time, and on the contrary, the increase of the surface area of the foil is prevented, and etching As a negative electrode material that solves the problem that the capacity increase of the negative electrode is limited by this, the thickness consisting of titanium fine particles with an average particle diameter of 0.02 to 1.0 µm formed in an inert atmosphere such as argon or helium on the surface of an appropriately roughened aluminum foil A cathode material coated with a 0.2-5.0 μm titanium vapor deposition film is disclosed. According to this cathode material, since the surface of the titanium deposition film is finely roughened, an increase in the surface area of the cathode material is achieved and, further, an increase in the capacity of the aluminum electrolytic capacitor is achieved. Moreover, the cathode material excellent in durability is obtained by the titanium vapor deposition film.

Japanese Patent Publication No. Hei 3-37293

However, there is always a request for further improving the capacity per unit volume without lowering the breakdown voltage for the electrolytic capacitor. This request can be answered if the capacity of the anode can be significantly increased. If it is an electrolytic capacitor of the same rated capacity value, since the size of the cathode or the anode can be reduced, miniaturization of the electrolytic capacitor is achieved. Moreover, if it is an electrolytic capacitor of the same volume, the capacity|capacitance of an electrolytic capacitor can be increased, and high capacity|capacitance is achieved.

Accordingly, it is an object of the present invention to provide an electrolytic capacitor having a negative electrode that exhibits a high capacity and a method for manufacturing the same, which can meet the request for miniaturization and high capacity by increasing the capacity per unit volume of the electrolytic capacitor.

As a result of diligent studies by the inventors, when an electrolytic capacitor is constructed using a cathode in which a conductive polymer layer is formed on a conductive substrate, the conductive polymer layer in contact with the ion conductive electrolyte in the capacitor exhibits redox capacity, and per unit volume of the capacitor is used. The invention was completed by discovering that the capacity was significantly increased.

Therefore, the present invention first

A cathode having a conductive substrate and a conductive polymer layer provided on a surface of the conductive substrate;

an anode having a base made of a valve metal and a dielectric layer made of an oxide of the valve metal provided on a surface of the base, wherein the dielectric layer and the conductive polymer layer of the cathode are disposed to face each other with a space;

An electrolytic capacitor having an ion conductive electrolyte filled in the space,

It relates to an electrolytic capacitor characterized in that the conductive polymer layer of the negative electrode in contact with the ion conductive electrolyte by applying a voltage between the positive electrode and the negative electrode expresses a redox capacity.

The negative electrode which has a conductive polymer layer in the electrolytic capacitor of this invention shows the capacity|capacitance which increased remarkably by expression of redox capacity compared with the negative electrode which does not have a conductive polymer layer, Furthermore, the capacity per unit volume of an electrolytic capacitor significantly increases For the redox capacity to be expressed, the conductive polymer layer of the anode needs to be in direct contact with the ion conductive electrolyte, but the dielectric layer of the anode may be in direct contact with the ion conductive electrolyte or indirectly with the ion conductive electrolyte through another conductive material. You may be connected. In addition, the ion conductive electrolyte may be held in the separator. It is preferable that the conductive substrate of the cathode has a titanium vapor deposition film, and the conductive polymer layer is provided on the surface of the titanium vapor deposition film. The titanium-deposited film provides a cathode with excellent durability.

For the conductive polymer layer formed on the surface of the conductive base of the negative electrode, a known conductive polymer derived from a monomer having a π-conjugated double bond can be used without particular limitation, but the conductive polymer layer is poly(3,4-ethylene). dioxythiophene) (hereinafter, 3,4-ethylenedioxythiophene is denoted as "EDOT" and poly(3,4-ethylenedioxythiophene) is denoted as "PEDOT"). Since PEDOT shows high redox activity and is excellent also in heat resistance, it can be used preferably in this invention.

By using the negative electrode provided with the thin conductive polymer layer, the size of the negative electrode or the positive electrode can be reduced, and further, the capacity per unit volume of the electrolytic capacitor can be improved. It is preferable that the range of the thickness of the conductive polymer layer of a cathode is 200-2450 nm. When the thickness of the conductive polymer layer is less than 200 nm, the tendency for high temperature durability to decrease is confirmed, and when the thickness of the conductive polymer layer is thicker than 2450 nm, the temperature dependence of the capacity becomes large, and it becomes difficult to contribute to the miniaturization of the electrolytic capacitor.

The conductive polymer layer on the conductive substrate of the negative electrode may be formed by electrolytic polymerization, may be formed by chemical polymerization, or may be formed by applying a dispersion liquid containing particles of the conductive polymer to the surface of the conductive substrate. It is preferable to form by By electrolytic polymerization, a conductive polymer layer excellent in mechanical strength can be formed on the surface of the substrate from a small amount of monomer in a short time. Moreover, electrolytic polymerization can provide a thin, dense, uniform conductive polymer layer, and can obtain easily the suitable conductive polymer layer which has a thickness in the range of 200-2450 nm.

The present invention also provides a method for manufacturing the electrolytic capacitor of the present invention as described above,

A cathode forming step of forming a conductive polymer layer on the surface of a conductive substrate to obtain a cathode for the electrolytic capacitor;

an anode forming step of oxidizing the surface of a substrate made of a valve metal to form a dielectric layer made of an oxide of the valve metal to obtain an anode for the electrolytic capacitor; and

It relates to a method of manufacturing an electrolytic capacitor, comprising an electrolyte charging step of filling the space with an ion conductive electrolyte by opposing the conductive polymer layer of the negative electrode and the dielectric layer of the positive electrode with a space therebetween. In this method, it is preferable to perform formation of the conductive polymer layer in the said cathode formation process by electrolytic polymerization.

(Effects of the Invention)

According to the electrolytic capacitor of the present invention, by applying a voltage between the positive electrode and the negative electrode, the conductive polymer layer of the negative electrode in contact with the ion conductive electrolyte expresses a redox capacity, and the capacity per unit volume of the electrolytic capacitor is remarkably increased. Accordingly, it is possible to achieve miniaturization and high capacity of the electrolytic capacitor.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows the relationship between the film thickness of the PEDOT electrolytic polymerization film in a cathode, and capacity|capacitance.
Fig. 2 is a diagram showing a cyclic voltammogram in an electrolyte solution of a negative electrode having a PEDOT electrolytic polymerization film.
It is a figure which shows the relationship between the film thickness of the PEDOT electrolytic polymerization film of the negative electrode in an electrolytic capacitor, and the temperature change of capacitor|capacitor capacity|capacitance.

The electrolytic capacitor of the present invention has a conductive base, a cathode having a conductive polymer layer provided on the surface of the conductive base, a base made of a valve metal, and a dielectric layer made of an oxide of the valve metal provided on the surface of the base, An electrolytic capacitor comprising: an anode in which a dielectric layer and a conductive polymer layer of the cathode are disposed to face each other with a space; When the conductive polymer layer of the negative electrode in contact with the electrolyte expresses redox capacity, the capacity per unit volume of the electrolytic capacitor remarkably increases. This capacitor can be manufactured by the negative electrode formation process, positive electrode formation process, and electrolyte filling process shown below. Hereinafter, each process is demonstrated in detail.

(1) cathode forming process

The cathode in the electrolytic capacitor of this invention has an electroconductive base and the electroconductive polymer layer provided in the surface of the said electroconductive base. The conductive substrate can be used without particular limitation as long as it can be used as a current collector. For example, a valve metal foil such as aluminum, tantalum, niobium, titanium, or zirconium used for a cathode in a conventional electrolytic capacitor, or a valve metal foil to increase the surface area by chemical or electrochemical etching treatment Foil can be used as a base|substrate, and the oxide film may exist on the surface of these foils. In addition, a conductive material such as carbon, titanium, platinum, gold, silver, cobalt, nickel, iron is vacuum deposited, sputtering, ion plating, A base having a structure laminated by means of application or the like can also be suitably used. The oxide film on the valve metal foil may be a natural oxide film or a film formed by chemical conversion treatment using a chemical solution such as an aqueous ammonium borate solution, an aqueous ammonium adipate solution, or an aqueous ammonium phosphate solution. In addition, an alloy such as an aluminum-copper alloy may be used as the conductive substrate.

Aluminum is preferable as the valve metal. In addition, a substrate in which a titanium film is laminated on the surface of an aluminum foil subjected to an etching treatment as necessary or on the surface of an aluminum oxide film of an aluminum foil provided with an aluminum oxide film is preferable because it provides a cathode with excellent durability. A vapor deposition method is preferable as the formation method of the titanium film, and the titanium vapor deposition film may contain atoms in the ambient atmosphere in the vapor deposition process, and may contain, for example, nitrogen or carbon. Among them, a titanium-deposited film containing carbon is preferable because it provides a polymer film exhibiting stable characteristics in electrolytic polymerization shown below.

A conductive polymer layer is provided on the surface of the substrate. An electrolytic polymerization film or a chemical polymerization film may be sufficient as this conductive polymer layer, and it may form using the dispersion liquid containing at least the particle|grains of a conductive polymer and a dispersion medium.

The electrolytic polymerization film is formed by introducing the gas and a counter electrode into a polymerization solution containing at least a monomer, a supporting electrolyte, and a solvent, and applying a voltage between the substrate and the counter electrode. As the counter electrode, a plate or a mesh made of platinum, nickel, or steel can be used. Anions released from the supporting electrolyte in the course of electrolytic polymerization are included in the conductive polymer layer as a dopant.

As the solvent of the polymerization liquid for electrolytic polymerization, a solvent capable of dissolving a desired amount of a monomer and a supporting electrolyte and not adversely affecting the electrolytic polymerization can be used without any particular limitation. Examples include water, methanol, ethanol, isopropanol, butanol, ethylene glycol, acetonitrile, butyronitrile, acetone, methyl ethyl ketone, tetrahydrofuran, 1,4-dioxane, γ-butyrolactone, methyl acetate, ethyl acetate, and methyl benzoate, ethyl benzoate, ethylene carbonate, propylene carbonate, nitromethane, nitrobenzene, sulfolane, and dimethyl sulfolane. These solvents may be used independently and may mix and use 2 or more types. The use of a solvent containing water in an amount of 80% by mass or more of the total solvent, particularly a solvent consisting only of water, is preferable because a dense and stable electrolytic polymerization film can be obtained.

As a monomer contained in the polymerization liquid for electrolytic polymerization, a monomer having a π-conjugated double bond, which has been conventionally used for the production of a conductive polymer, can be used without particular limitation. Representative monomers are exemplified below. These monomers may be used independently and may be used as a mixture of 2 or more types.

First, thiophene and thiophene derivatives, for example, 3-alkylthiophene such as 3-methylthiophene and 3-ethylthiophene, 3,4-dimethylthiophene, 3,4-diethylthiophene, etc. 3-alkoxythiophene such as ,4-dialkylthiophene, 3-methoxythiophene and 3-ethoxythiophene, 3,4-dimethoxythiophene, 3,4-diethoxythiophene, etc. 3,4-alkylenedioxythiophene, 3,4-methyleneoxythiophene, such as dialkoxythiophene, 3,4-methylenedioxythiophene, EDOT, and 3,4-(1,2-propylenedioxy)thiophene 3,4-alkyleneoxythiathiophene, 3,4-methylenedithiathiophene, such as athiophene, 3,4-ethyleneoxythiathiophene, 3,4-(1,2-propyleneoxythia)thiophene, 3 3,4-alkylenedithiathiophene, such as ,4-ethylenedithiathiophene, 3,4-(1,2-propylenedithia)thiophene, thieno[3,4-b]thiophene, isopropylthiene and alkylthieno[3,4-b]thiophenes such as no[3,4-b]thiophene and t-butyl-thieno[3,4-b]thiophene.

In addition, pyrrole and pyrrole derivatives, for example, N-alkylpyrrole such as N-methylpyrrole and N-ethylpyrrole, 3-alkylpyrrole such as 3-methylpyrrole and 3-ethylpyrrole, 3-methoxypyrrole, 3- 3,4-dialkylpyrrole, 3,4-dialkylpyrrole, such as 3-alkoxypyrrole such as ethoxypyrrole, N-phenylpyrrole, N-naphthylpyrrole, 3,4-dimethylpyrrole, and 3,4-diethylpyrrole 3,4-dialkoxypyrroles such as methoxypyrrole and 3,4-diethoxypyrrole are exemplified. In addition, aniline and aniline derivatives such as 2,5-dialkylaniline such as 2,5-dimethylaniline and 2-methyl-5-ethylaniline, 2,5-dimethoxyaniline, 2-methoxy-5- 2,3,5-trialkoxyaniline, such as 2,5-dialkoxyaniline, such as ethoxyaniline, 2,3,5-trimethoxyaniline, 2,3,5-triethoxyaniline, 2,3, 2,3,5,6-tetraalkoxyaniline such as 5,6-tetramethoxyaniline, 2,3,5,6-tetraethoxyaniline, and furan and furan derivatives such as 3-methylfuran, 3 - 3-alkylfuran such as ethylfuran, 3,4-dialkylfuran such as 3,4-dimethylfuran and 3,4-diethylfuran, 3-alkoxyfuran such as 3-methoxyfuran and 3-ethoxyfuran 3,4-dialkoxyfuran such as furan, 3,4-dimethoxyfuran, and 3,4-diethoxyfuran;

As the monomer, it is preferable to use a monomer selected from the group consisting of thiophenes having a substituent at the 3-position and the 4-position. The substituents at the 3rd and 4th positions of the thiophene ring may form a ring together with the carbons at the 3rd and 4th positions. In particular, EDOT is preferable because it exhibits high redox activity and provides PEDOT excellent in heat resistance.

As a supporting electrolyte contained in the polymerization liquid for electrolytic polymerization, the compound which discharge|releases the dopant contained in the conventional conductive polymer can be used without limitation in particular. For example, in addition to inorganic acids such as boric acid, nitric acid, phosphoric acid, tungstophosphoric acid, molybdophosphoric acid, and organic acids such as acetic acid, oxalic acid, citric acid, ascortic acid, tartaric acid, squaric acid, rhodizonic acid, croconic acid, and salicylic acid methanesulfonic acid, dodecylsulfonic acid, trifluoromethanesulfonic acid, p-toluenesulfonic acid, dodecylbenzenesulfonic acid, 1,2-dihydroxy-3,5-benzenedisulfonic acid, naphthalenesulfonic acid, naphthalenedisulfonic acid, propylnaphthalenesulfonic acid , sulfonic acids such as butylnaphthalenesulfonic acid, and salts thereof. In addition, polycarboxylic acids such as polyacrylic acid, polymethacrylic acid, and polymaleic acid, polysulfonic acids such as polystyrenesulfonic acid and polyvinylsulfonic acid, and salts thereof can also be used as the supporting electrolyte.

In addition, borodisalicylic acid, borodioxalic acid, borodimalonic acid, borodisuccinic acid, borodiadipic acid, borodimaleic acid, borodiglycolic acid, borodilactic acid, borodihydroxyisobutyric acid, borodimalic acid, borodimalic acid Boron complexes, such as rhoditartaric acid, borodistric acid, borodiphthalic acid, borodihydroxybenzoic acid, borodimandelic acid, and borodibenzylic acid, Formula (I) or Formula (II)

[In the formula, m is an integer of 1 to 8, preferably an integer of 1 to 4, particularly preferably 2, and n is an integer of 1 to 8, preferably an integer of 1 to 4, particularly preferably means 2, and o means an integer of 2 or 3] and salts thereof can also be used as the supporting electrolyte.

Examples of the salt include alkali metal salts such as lithium salts, sodium salts and potassium salts, ammonium salts, ethylammonium salts and butylammonium salts, dialkylammonium salts such as diethylammonium salts and dibutylammonium salts, triethylammonium salts, tributylammonium salts, etc. Tetraalkylammonium salts, such as an alkylammonium salt, a tetraethylammonium salt, and a tetrabutylammonium salt, are illustrated.

These supporting electrolytes may be used alone or in mixture of two or more, depending on the type of supporting electrolyte, in an amount equal to or less than the saturation solubility in the polymerization solution, and a concentration at which a sufficient current for electrolytic polymerization is obtained; Preferably, it is used at a concentration of 10 mM or more with respect to 1 liter of water. When electrolytic polymerization of a thiophene monomer having substituents at the 3rd and 4th positions, preferably EDOT, in a solvent containing a lot of water, preferably only water, the boron complex and its salt, preferably borodisalicylic acid And when the salt is used, since the conductive polymer layer excellent in thermal stability is formed, it is preferable.

Electrolytic polymerization in electrolytic polymerization is performed by any one of a potential method, a constant current method, and a potential sweep method. In the case of the potentiostatic method, although it depends on the type of monomer, a potential of 1.0 to 1.5 V is suitable for a saturated calomel electrode. In the case of the constant current method, although it depends on the type of the monomer, a current value of 1 to 10000 μA/cm2 This is suitable, and in the case of the potential sweep method, it depends on the type of monomer, but it is suitable to sweep the range of 0 to 1.5 V with respect to the saturated calomel electrode at a rate of 5 to 200 mV/sec. The conductive polymer layer is preferably formed on the substrate with a thickness of 200 to 2450 nm by electrolytic polymerization. The polymerization temperature is not strictly limited, but is generally in the range of 10 to 60°C. The polymerization time is also not strictly limited, but is generally in the range of 1 minute to 10 hours.

The chemical polymerization film is formed by preparing a solution in which both a monomer and an oxidizing agent are dissolved in a solvent, and applying this solution to the surface of the conductive substrate by brush coating, drip coating, immersion coating, spray coating, etc. A liquid in which a monomer is dissolved and a liquid in which an oxidizing agent is dissolved in a solvent are prepared, and these liquids are alternately applied to the surface of the conductive substrate by brush application, drip application, immersion application, spray application, etc. can Examples of the solvent include water, methanol, ethanol, isopropanol, butanol, ethylene glycol, acetonitrile, butyronitrile, acetone, methyl ethyl ketone, tetrahydrofuran, 1,4-dioxane, γ-butyrolactone, acetic acid. Methyl, ethyl acetate, methyl benzoate, ethyl benzoate, ethylene carbonate, propylene carbonate, nitromethane, nitrobenzene, sulfolane, and dimethyl sulfolane can be used. These solvents may be used independently and may mix and use 2 or more types. As the monomer, a monomer having a ?-conjugated double bond, for example, a monomer exemplified for electrolytic polymerization can be used. These monomers may be used independently and may be used as a mixture of 2 or more types. As the monomer, a monomer selected from thiophenes having a substituent at the 3-position and the 4-position is preferable, and EDOT is particularly preferable. As the oxidizing agent, a trivalent iron salt such as iron(III) p-toluenesulfonate, iron(III) naphthalenesulfonate, or iron(III) anthraquinonesulfonate, or a persulfate such as ammonium peroxodisulfate or sodium peroxodisulfate, etc. can be used. and a single compound may be used and 2 or more types of compounds may be used. The polymerization temperature is not strictly limited, but is generally in the range of 10 to 60°C. The polymerization time is also not strictly limited, but is generally in the range of 1 minute to 10 hours.

In addition, the conductive polymer layer can also be formed by applying the dispersion liquid containing at least particle|grains of a conductive polymer and a dispersion medium to the surface of the said conductive base by means, such as application|coating and dripping, and drying. Examples of the dispersion medium in the dispersion liquid include water, methanol, ethanol, isopropanol, butanol, ethylene glycol, acetonitrile, butyronitrile, acetone, methyl ethyl ketone, tetrahydrofuran, 1,4-dioxane, γ- Butyrolactone, methyl acetate, ethyl acetate, methyl benzoate, ethyl benzoate, ethylene carbonate, propylene carbonate, nitromethane, nitrobenzene, sulfolane and dimethyl sulfolane can be used, but water is preferably used as the dispersion medium. The dispersion is, for example, added to water, a monomer, an acid or a salt thereof releasing a dopant, and an oxidizing agent, stirred until chemical oxidation polymerization is complete, followed by ultrafiltration, cation exchange, anion exchange, etc. It can be obtained by removing an oxidizing agent and a residual monomer by a purification means, and then performing dispersion treatment such as ultrasonic dispersion treatment, high-speed fluid dispersion treatment, high-pressure dispersion treatment, etc. if necessary. In addition, a monomer and an acid or a salt thereof that releases a dopant are added to water, electrolytic oxidation polymerization is carried out while stirring, and then residual monomers are removed by purification means such as ultrafiltration, cation exchange, and anion exchange, followed by ultrasonication if necessary. It can obtain by performing dispersion processing, such as a dispersion process, a high-speed fluid dispersion process, and a high pressure dispersion process. In addition, the liquid obtained by the chemical oxidation polymerization method or the electrolytic polymerization method described above is filtered to separate the aggregates, and after sufficient washing, it is added to water and subjected to dispersion treatment such as ultrasonic dispersion treatment, high-speed fluid dispersion treatment, high-pressure dispersion treatment, etc. can be obtained by Content of the particle|grains of the conductive polymer in a dispersion liquid is generally the range of 1.0-3.0 mass %, Preferably it is the range of 1.5 mass % - 2.0 mass %.

By using the negative electrode provided with the thin conductive polymer layer, the size of the negative electrode can be reduced, and furthermore, the capacity per unit volume of the capacitor can be improved. It is preferable that the range of the thickness of the conductive polymer layer of a cathode is 200-2450 nm. When the thickness of the conductive polymer layer is less than 200 nm, a tendency for high temperature durability to decrease is confirmed, and when the thickness of the conductive polymer layer is thicker than 2450 nm, the temperature dependence of the capacity becomes large, and it becomes difficult to contribute to the miniaturization of the electrolytic capacitor.

It is preferable to form the conductive polymer layer of a cathode by electrolytic polymerization. A conductive polymer layer excellent in mechanical strength can be formed on the surface of the conductive base by electrolytic polymerization from a small amount of monomer in a short time. In addition, electrolytic polymerization provides a thin, dense, and uniform conductive polymer layer, and a suitable conductive polymer layer having a thickness in the range of 200 to 2450 nm can be easily obtained. On the other hand, since the chemical polymerization film has a non-uniform film quality and has a thickness of about 3 μm even when thin, it is not suitable for downsizing the capacitor. In addition, in order to obtain a suitable conductive polymer layer having a thickness in the range of 200 to 2450 nm using the dispersion, it is complicated in general that the process of applying and drying the dispersion to the conductive substrate must be repeated. Further, although the reason is not clear at present, the electrolytic capacitor having a negative electrode having a conductive polymer layer obtained from the dispersion has a lower capacity and higher equivalent series resistance compared with an electrolytic capacitor having a negative electrode having an electrolytic polymerization film having the same thickness. could see that

(2) anode forming process

The anode in the electrolytic capacitor of the present invention has a base made of a valve metal such as aluminum, tantalum, niobium, titanium, or zirconium, and a dielectric layer made of an oxide of the valve metal provided on the surface of the base. As the substrate for the anode, it is preferable to increase the surface area by chemically or electrochemically etching the valve metal foil by a known method, and an aluminum foil to which the etching treatment is performed is particularly preferable. The dielectric layer on the surface of the substrate can be formed by a known method in which the substrate is subjected to chemical conversion treatment using a chemical solution such as an aqueous ammonium borate solution, an aqueous ammonium adipate solution, or an aqueous ammonium phosphate solution.

(3) Electrolyte filling process

In this step, the negative electrode obtained in the above negative electrode forming step and the positive electrode obtained in the above positive electrode forming step are arranged and combined so that the conductive polymer layer of the negative electrode and the dielectric layer of the positive electrode face each other with a space, and then the space is filled with an ion conductive electrolyte do.

As the ion conductive electrolyte, a known ion conductive electrolyte that does not have electronic conductivity can be used without particular limitation. First, an electrolyte solution used for a conventional electrolytic capacitor, for example, γ-butyrolactone, δ-valerolactone, ethylene glycol, ethylene glycol monomethyl ether, sulfolane, propylene carbonate, acetonitrile, a solvent such as water An electrolytic solution in which a solute such as phthalate, salicylate, benzoate, adipate, maleate, or borate is dissolved can be used. Examples of the salt include amidinium salts, imidazolinium salts, pyrimidinium salts, phosphonium salts, ammonium salts, amine salts, and alkali metal salts. A single compound or a mixture of 2 or more types may be sufficient as the solvent of electrolyte solution, A single compound may be sufficient as a solute, or 2 or more types of mixture may be sufficient as it. A gelling agent may be contained in these electrolyte solutions. Moreover, room temperature molten salt (ionic liquid) can be used as an ion conductive electrolyte.

For example, this process is carried out by impregnating the electrolyte or ionic liquid in a capacitor element formed by laminating the strip-shaped cathode and the anode through a separator so that the conductive polymer layer of the cathode and the dielectric layer of the anode face each other, and then winding the same. can do. In addition, this step can be carried out by impregnating the electrolytic solution or the ionic liquid into a capacitor element formed by laminating the cathode and the anode having a desired shape through a separator so that the conductive polymer layer of the cathode and the dielectric layer of the anode face each other. The electrolytic solution or the ionic liquid may be impregnated into a capacitor element in which a plurality of sets of cathodes and anodes are alternately stacked with a separator interposed therebetween so that the conductive polymer layer of the cathode and the dielectric layer of the anode face each other. As the separator, in addition to woven or nonwoven fabrics composed of cellulose fibers, such as manila paper, kraft paper, esparto paper, hemp paper, cotton paper, and their blended paper, synthetic fiber paper, glass paper, glass paper and Manila paper, kraft paper and mixed paper, etc. can be used. The impregnation with the electrolytic solution or the ionic liquid may be performed after the capacitor element is accommodated in an external case having an opening. If an electrolyte containing a gelling agent is used, the electrolyte can be made into a gel by heating the capacitor element after impregnating it with the electrolyte.

Further, this step may be carried out by filling the space formed by the spacer of a capacitor element formed by opposing the conductive polymer layer of the negative electrode and the dielectric layer of the positive electrode through an insulating spacer by filling the space formed by the spacer. In this form, as an ion conductive electrolyte, in addition to the electrolyte or ionic liquid, a gel electrolyte in which the electrolyte is absorbed, such as polyvinylidene fluoride, polyacrylonitrile, or the above-mentioned salt and polyethylene oxide, polymethacrylate, polyacrylate A solid electrolyte composed of a composite of a high molecular compound such as these can also be used. A gel or solid electrolyte may be laminated on the conductive polymer layer of the negative electrode, and then the positive electrode may be laminated on the electrolyte so that the dielectric layer is in contact.

In the present invention, the conductive polymer layer of the negative electrode needs to be in direct contact with the ion conductive electrolyte, and the conductive polymer layer of the negative electrode is not in direct contact with the positive electrode but is connected (conducted) to the positive electrode through the ion conductive electrolyte, but the dielectric layer of the positive electrode The silver may be in direct contact with the ion conductive electrolyte, or may be indirectly connected to the ion conductive electrolyte through another conductive material. As another suitable conductive material, a conductive polymer layer is mentioned. This conductive polymer layer can be formed by electrolytic polymerization or chemical polymerization on the surface of the dielectric layer of the anode after the anode is formed in the anode forming step, and a dispersion containing at least particles of the conductive polymer and a dispersion medium is applied to the anode. It can also be formed by applying to the surface of the dielectric layer of About this conductive polymer layer, since description regarding formation of the conductive polymer layer of the negative electrode mentioned above is suitable as it is, further description is abbreviate|omitted. When the conductive polymer layer is provided adjacent to the dielectric layer of the positive electrode, the conductive layer and the conductive polymer layer of the negative electrode are arranged to face each other with a space therebetween and combined, and then the space may be filled with an ion conductive electrolyte.

When a voltage is applied between the anode and the cathode of the capacitor element accommodated and sealed in the outer case, the redox capacity is expressed in the conductive polymer layer of the cathode in contact with the ion conductive electrolyte, so the capacity per unit volume of the electrolytic capacitor is remarkable. increase significantly An anion in the ion conductive electrolyte is introduced as a dopant into the conductive polymer layer of the negative electrode in the process of redox capacity expression.

Example

The present invention will be described using the following examples, but the present invention is not limited to the following examples.

(1) Preparation and capacity evaluation of negative electrode

cathode 1

50 ml of distilled water was introduced into a glass container and heated to 40°C. To this solution, 0.021 M EDOT and 0.08 M ammonium borodisalicylate were added in this order and stirred to obtain a polymerization solution for electrolytic polymerization in which all EDOT was dissolved.

An aluminum foil provided with an aluminum oxide film was punched with a projected area of 1 cm 2 , and a titanium vapor deposition film containing carbon was formed on the aluminum oxide film. An aluminum foil (gas, working electrode) provided with this titanium deposition film and a counter electrode of a SUS mesh having an area of 10 cm 2 were introduced into the above-described polymerization solution for electrolytic polymerization, and electrolytic polymerization was carried out under a condition of 100 μA/cm 2 . It was carried out for 3 minutes. The working electrode after polymerization was washed with water and dried at 100° C. for 30 minutes to obtain a cathode having a PEDOT layer thickness of 105 nm on the titanium vapor deposition film. In addition, the thickness of the PEDOT layer was carried out a plurality of times by changing the time of constant current electrolytic polymerization under the condition of 100 μA / ㎠, and the thickness of the PEDOT layer obtained in each experiment was measured using an atomic force microscope or a step meter. , It is a value obtained by deriving the relational expression between the thickness of the PEDOT layer and the amount of charge, and converting the charge amount of the electrolytic polymerization into the thickness of the PEDOT layer using the derived relational expression. Also in the following electrolytic polymerization experiment, the thickness of the PEDOT layer was calculated|required using the same relational expression.

Cathode 2

The thickness of the PEDOT layer on the titanium deposition film by repeating the manufacturing procedure of the cathode 1, except that, instead of carrying out the galvanostatic electrolytic polymerization under the condition of 100㎂/cm2 for 3 minutes, the galvanostatic electrolytic polymerization was performed under the condition of 100㎂/cm2 for 6 minutes. A cathode having a 210 nm was obtained.

Cathode 3

The thickness of the PEDOT layer on the titanium-deposited film was repeated by repeating the manufacturing procedure of the cathode 1, except that, instead of carrying out the constant current electrolytic polymerization under the condition of 100 μA/cm 2 for 3 minutes, the constant current electrolytic polymerization was performed at the condition of 100 μA/cm 2 for 10 minutes. A negative electrode having a value of 350 nm was obtained.

cathode 4

The thickness of the PEDOT layer on the titanium-deposited film was repeated by repeating the manufacturing procedure of the cathode 1, except that, instead of carrying out the constant current electrolytic polymerization under the condition of 100 μA/cm 2 for 3 minutes, the constant current electrolytic polymerization was performed under the condition of 100 μ A/cm 2 for 20 minutes. A negative electrode having a value of 700 nm was obtained.

cathode 5

The thickness of the PEDOT layer on the titanium-deposited film was repeated by repeating the manufacturing procedure of the cathode 1, except that, instead of carrying out the galvanostatic electrolytic polymerization under the condition of 100 μA/cm 2 for 3 minutes, the galvanostatic electrolytic polymerization was performed under the condition of 100 μA/cm 2 for 30 minutes. A cathode having a 1050 nm was obtained.

cathode 6

The thickness of the PEDOT layer on the titanium-deposited film was repeated by repeating the manufacturing procedure of the cathode 1, except that the galvanostatic electrolytic polymerization was performed for 50 minutes under the condition of 100 μA/cm 2 instead of the constant current electrolytic polymerization at the condition of 100 μA/cm 2 for 3 minutes A negative electrode with 1750 nm was obtained.

Cathode 7

The thickness of the PEDOT layer on the titanium-deposited film was repeated by repeating the manufacturing procedure of the cathode 1, except that, instead of carrying out the galvanostatic electrolytic polymerization under the condition of 100㎂/cm2 for 3 minutes, the galvanostatic electrolytic polymerization was performed under the condition of 100㎂/cm2 for 70 minutes. A cathode was obtained with a value of 2450 nm.

cathode 8

The thickness of the PEDOT layer on the titanium deposition film by repeating the manufacturing procedure of the cathode 1, except that, instead of carrying out the galvanostatic electrolytic polymerization under the condition of 100㎂/cm2 for 3 minutes, the galvanostatic electrolytic polymerization was performed under the condition of 100㎂/cm2 for 100 minutes. A cathode having a value of 3500 nm was obtained.

cathode 9

The thickness of the PEDOT layer on the titanium-deposited film was repeated by repeating the manufacturing procedure of the cathode 1, except that, instead of carrying out the constant current electrolytic polymerization under the condition of 100 μA/cm 2 for 3 minutes, the constant current electrolytic polymerization was performed under the condition of 100 μ A/cm 2 for 200 minutes. A negative electrode with 7000 nm was obtained.

Anodes 1 to 9 were introduced into an electrolyte solution in which an amidinium salt of phthalic acid was dissolved in γ-butyrolactone at a concentration of 15% by mass, and the capacity of each cathode at 120 Hz under the conditions of 30 ° C and 70 ° C was measured. . 1 shows the relationship between the thickness of the PEDOT layer and the capacity. In addition, the capacity|capacitance of the aluminum foil (base) provided with a titanium vapor deposition film was 39 F/cm<2>.

From Fig. 1, the capacity increases until the thickness of the PEDOT layer reaches 1050 nm in the measurement at 30 ° C and the measurement at 70 ° C. In the range of 1050 nm to 3500 nm, an approximately constant capacity value is obtained, , it can be seen that the capacitance slightly decreases when the thickness of the PEDOT layer exceeds 3500 nm. In addition, it was found that each cathode exhibited a significantly increased capacity value compared to that of the gas, and that even the cathode 1 (PEDOT layer: 105 nm) had a capacity of about 60 times the capacity of the gas at 30°C.

In order to elucidate the cause of the increase in the capacity of the negative electrode provided with the PEDOT layer, the electrochemical response of the negative electrode provided with the PEDOT layer was evaluated by a cyclic voltammogram. In the electrolyte solution described above, a cathode 2 as a working electrode and any one of the above gases, a platinum mesh having an area of 4 cm 2 as a counter electrode, and a silver-silver chloride electrode as a reference electrode were introduced, and the scanning potential range was changed to -0.8V to +0.4. It was set as V, and it evaluated by setting the scanning speed as 10 mV/s. The results are shown in FIG. 2 . As is evident from FIG. 2, neither oxidation nor reduction waves are confirmed in the cyclic voltammogram of the gas, but in the cyclic voltammogram of the cathode 2, oxidation waves and dedoping are shown in a very narrow range around -0.1 V. A reducing wave was confirmed. This indicates that a rapid charge/discharge reaction is occurring. Therefore, it was determined that the increase in the capacity of the negative electrode having the PEDOT layer was due to the expression of this redox capacity.

(2) Manufacturing and capacity evaluation of electrolytic capacitors

Example 1

50 ml of distilled water was introduced into a glass container and heated to 40°C. To this solution, 0.021 M EDOT and 0.08 M ammonium borodisalicylate were added in this order and stirred to obtain a polymerization solution for electrolytic polymerization in which all EDOT was dissolved. An aluminum foil provided with an aluminum oxide film was punched with a projected area of 2 cm 2 , and a titanium vapor deposition film containing carbon was formed on the aluminum oxide film to obtain a cathode substrate. Next, this cathode substrate (working electrode) and a counter electrode of SUS mesh having an area of 10 cm 2 were introduced into the above-described polymerization liquid for electrolytic polymerization, and constant current electrolytic polymerization was performed under the condition of 100 μA/cm 2 for 3 minutes. The working electrode after polymerization was washed with water and dried at 100° C. for 30 minutes to obtain a cathode having a PEDOT layer thickness of 105 nm on the titanium vapor deposition film.

After forming an aluminum oxide film by chemical conversion treatment on the surface of the aluminum foil subjected to etching treatment to increase the surface area, a hole was drilled with a projected area of 2 cm 2 to obtain an anode (capacity: 370 µF/cm 2 ). Next, a capacitor element in which the positive electrode and the negative electrode are laminated through a cellulosic separator is created, and the element is impregnated with an electrolyte solution obtained by dissolving amidinium salt of phthalic acid in γ-butyrolactone at a concentration of 15% by mass to laminate pack. did. Next, an aging treatment in which a voltage of 2.9 V was applied for 60 minutes was performed at a temperature of 110° C. to obtain a flat electrolytic capacitor. For this capacitor, the capacitance and equivalent series resistance were measured under the condition of 120 Hz.

Example 2

The procedure of Example 1 was repeated, except that the galvanostatic electrolytic polymerization was carried out for 6 minutes under the condition of 100 μA/cm 2 instead of the constant current electrolytic polymerization under the condition of 100 μA/cm 2 for 3 minutes. The thickness of the PEDOT layer on the titanium vapor deposition film in the cathode is 210 nm.

Example 3

The procedure of Example 1 was repeated, except that the galvanostatic electrolytic polymerization was carried out under the condition of 100 μA/cm 2 for 10 minutes instead of being carried out for 3 minutes under the condition of 100 μA/cm 2 . The thickness of the PEDOT layer on the titanium vapor deposition film in the cathode is 350 nm.

Example 4

The procedure of Example 1 was repeated, except that the galvanostatic electrolytic polymerization was carried out under the condition of 100 μA/cm 2 for 20 minutes instead of being carried out for 3 minutes under the condition of 100 μA/cm 2 . The thickness of the PEDOT layer on the titanium vapor deposition film in the cathode is 700 nm.

Example 5

The procedure of Example 1 was repeated, except that the galvanostatic electrolytic polymerization was carried out under the condition of 100 μA/cm 2 for 30 minutes instead of being carried out for 3 minutes under the condition of 100 μA/cm 2 . The thickness of the PEDOT layer on the titanium vapor deposition film in the cathode is 1050 nm.

Example 6

The procedure of Example 1 was repeated, except that the galvanostatic electrolytic polymerization was carried out for 50 minutes under the condition of 100 μA/cm 2 instead of the condition of 100 μA/cm 2 for 3 minutes. The thickness of the PEDOT layer on the titanium vapor deposition film in the cathode is 1750 nm.

Example 7

The procedure of Example 1 was repeated, except that the galvanostatic electrolytic polymerization was performed under the condition of 100 μA/cm 2 for 70 minutes instead of being carried out for 3 minutes under the condition of 100 μA/cm 2 . The thickness of the PEDOT layer on the titanium vapor deposition film in the cathode is 2450 nm.

Example 8

The procedure of Example 1 was repeated, except that the galvanostatic electrolytic polymerization was carried out under the condition of 100 μA/cm 2 for 100 minutes instead of being carried out for 3 minutes under the condition of 100 μA/cm 2 . The thickness of the PEDOT layer on the titanium vapor deposition film in the cathode is 3500 nm.

Example 9

200 μl of an aqueous dispersion (trade name: BAYTRON P: manufactured by HC Starck GmbH) containing commercially available particles of a complex of PEDOT and polystyrene sulfonate ions was cast on the negative electrode substrate used in Example 1, and spin at a rotation speed of 3000 rpm for 30 seconds did the coat. Then, it dried at 150 degreeC for 30 minutes, and obtained the cathode whose thickness of the PEDOT layer on a titanium vapor deposition film was about 100 nm. Next, a capacitor element in which the positive electrode used in Example 1 and the negative electrode were laminated via a cellulosic separator was created, and this element was impregnated with the electrolyte solution used in Example 1 and laminated. Next, an aging treatment in which a voltage of 2.9 V was applied for 60 minutes was performed at a temperature of 110° C. to obtain a flat electrolytic capacitor. The capacitance and equivalent series resistance were measured for this capacitor under the condition of 120 Hz.

Example 10

200 μl of an aqueous dispersion (trade name: BAYTRON P: manufactured by HC Starck GmbH) containing commercially available particles of a complex of PEDOT and polystyrene sulfonate ions was cast on the negative electrode substrate used in Example 1, and spin at a rotation speed of 3000 rpm for 30 seconds Coating was performed, followed by drying at 150°C for 30 minutes. This cast-drying process was repeated 6 more times to obtain a cathode having a thickness of the PEDOT layer on the titanium vapor deposition film of about 700 nm. The procedure of Example 9 was repeated except that this negative electrode was used in place of the negative electrode of Example 9.

Example 11

After apply|coating the ethanol solution containing 20 mass % EDOT on the negative electrode base|substrate used in Example 1, it dried at room temperature. Then, an ethanol solution containing iron(III) p-toluenesulfonate as an oxidizing agent at a concentration of 20% by mass was applied, dried at room temperature for 10 minutes, and then treated at a high temperature. This chemical oxidation polymerization process was repeated to obtain a cathode having a thickness of the PEDOT layer on the titanium vapor deposition film of about 5 μm. Next, a capacitor element in which the positive electrode used in Example 1 and the negative electrode were laminated via a cellulosic separator was created, and this element was impregnated with the electrolyte solution used in Example 1 and laminated. Next, an aging treatment in which a voltage of 2.9 V was applied for 60 minutes was performed at a temperature of 110° C. to obtain a flat electrolytic capacitor. For this capacitor, the capacitance and equivalent series resistance were measured under the condition of 120 Hz.

Example 12

50 ml of distilled water was introduced into a glass container, and 0.5 M pyrrole and 0.08 M ammonium borodisalicylate were added in this order and stirred at room temperature to obtain a polymerization solution for electrolytic polymerization in which all pyrroles were dissolved. An aluminum foil provided with an aluminum oxide film was punched with a projected area of 2 cm 2 , and a titanium vapor deposition film containing carbon was formed on the aluminum oxide film to obtain a cathode substrate. Next, this cathode base (working electrode) and a counter electrode of SUS mesh having an area of 10 cm 2 were introduced into the above-described polymerization solution for electrolytic polymerization, and constant current electrolytic polymerization was performed under the conditions of 100 μA/cm 2 for 10 minutes. The working electrode after polymerization was washed with water and then dried at 100° C. for 30 minutes to obtain a cathode having a polypyrrole layer thickness of 350 nm on the titanium vapor deposition film. Next, a capacitor element in which the positive electrode used in Example 1 and the negative electrode were laminated via a cellulosic separator was created, and this element was impregnated with the electrolyte solution used in Example 1 and laminated. Next, an aging treatment in which a voltage of 2.9 V was applied for 60 minutes was performed at a temperature of 110° C. to obtain a flat electrolytic capacitor. For this capacitor, the capacitance and equivalent series resistance were measured under the condition of 120 Hz.

Comparative Example 1

A capacitor element in which the negative electrode substrate used in Example 1 and the positive electrode used in Example 1 were laminated via a cellulosic separator was created, and this element was impregnated with the electrolyte solution used in Example 1 and laminated. Next, an aging treatment in which a voltage of 2.9 V was applied for 60 minutes was performed at a temperature of 110° C. to obtain a flat electrolytic capacitor. The capacity of this capacitor was measured under the condition of 120 Hz.

Comparative Example 2

The etched aluminum foil was punched in a projected area of 2 cm 2 to form a cathode. Next, a capacitor element in which this negative electrode and the positive electrode used in Example 1 were laminated via a cellulosic separator was created, and this element was impregnated with the electrolyte solution used in Example 1 and laminated. Next, an aging treatment in which a voltage of 2.9 V was applied for 60 minutes was performed at a temperature of 110° C. to obtain a flat electrolytic capacitor. For this capacitor, the capacitance and equivalent series resistance were measured under the condition of 120 Hz.

Comparative Example 3

The etched aluminum foil was punched with a projected area of 2 cm 2 , and titanium was vacuum-deposited under a nitrogen atmosphere to form a cathode. Next, a capacitor element in which this negative electrode and the positive electrode used in Example 1 were laminated via a cellulosic separator was created, and this element was impregnated with the electrolyte solution used in Example 1 and laminated. Next, an aging treatment in which a voltage of 2.9 V was applied for 60 minutes was performed at a temperature of 110° C. to obtain a flat electrolytic capacitor. The capacity of this capacitor was measured under the condition of 120 Hz.

The capacitance value (Cap) and equivalent series resistance (ESR) obtained in Table 1 are collectively shown.

As is apparent from Table 1, the electrolytic capacitors of Examples 1 to 8 having a cathode having a PEDOT layer obtained by electrolytic polymerization exhibit a significantly increased capacity compared with the conventional electrolytic capacitors of Comparative Examples 2 and 3, , showed a tendency to increase the capacitance of the capacitor as the thickness of the PEDOT layer increased. This result agrees well with the result shown in FIG. 1, and it can be seen that the increase in the capacitor capacity is due to the redox capacity of the negative electrode. Regarding the equivalent series resistance of the electrolytic capacitors of Examples 1 to 8, a value equal to or larger than the value of the equivalent series resistance in the conventional electrolytic capacitor of Comparative Example 2 is shown, and the thickness of the PEDOT layer is up to 2450 nm. Although the equivalent series resistance showed a tendency to decrease as the thickness increased, the equivalent series resistance also increased as the thickness increased. Moreover, even if it is the value of the equivalent series resistance of the capacitor|condenser of Example 1, there is no problem in particular practically. In addition, the electrolytic capacitor of Example 12 having a cathode having a polypyrrole layer obtained by electrolytic polymerization exhibited an equivalent capacity as compared with the electrolytic capacitor of Example 3 having a cathode having a PEDOT layer of the same thickness, and more It exhibited a low equivalent series resistance.

The electrolytic capacitors of Examples 9 and 10 having a cathode having a PEDOT layer obtained from the dispersion exhibit increased capacity compared to the conventional electrolytic capacitors of Comparative Examples 2 and 3, but having a PEDOT layer of the same thickness Compared with the electrolytic capacitors of Examples 1 and 4 provided with a negative electrode, it was limited to exhibiting a small capacity. Moreover, the equivalent series resistance of the electrolytic capacitors of Examples 9 and 10 was significantly increased compared with the equivalent series resistance of the electrolytic capacitors of Examples 1 and 4. The electrolytic capacitor of Example 11 having a cathode having a PEDOT layer obtained by chemical polymerization exhibited the largest capacity, but because it had a thick cathode, it was not suitable for manufacturing a small electrolytic capacitor. From these points, it was judged effective to form the conductive polymer layer of a negative electrode by electrolytic polymerization.

The electrolytic capacitors of Examples 1 to 5 provided with a cathode having a PEDOT layer obtained by electrolytic polymerization suitable for the manufacture of a small high-capacity electrolytic capacitor were subjected to a high-temperature load test in which a charge of 2.5 V was applied at 105° C. for 140 hours. Table 2 shows the ratio of the change in capacity after the load test to the capacity before the load test.

It can be seen from Table 2 that the electrolytic capacitor of Example 1 having a cathode having a PEDOT layer of 105 nm showed a large capacity change, but the capacity change rate of the electrolytic capacitor of Example 2 having a cathode having a PEDOT layer of 210 nm was - The electrolytic capacitor of Example 3 with a cathode having a PEDOT layer of 350 nm, the electrolytic capacitor of Example 4 with a cathode having a PEDOT layer of 700 nm, and a PEDOT layer of 1050 nm The capacity change rate of the electrolytic capacitor of Example 5 having a cathode having

Next, for the electrolytic capacitors of Examples 1 to 8 having a cathode having a PEDOT layer obtained by electrolytic polymerization suitable for the production of a small-sized high-capacity electrolytic capacitor, the capacitance value (Cap( -40°C)) and the capacity value (Cap(20°C)) at 20°C, and the ratio of {Cap(-40°C)-Cap(20°C)} to Cap(20°C) (this ratio is expressed as "ΔCap(-40°C/20°C)") as a measure, and the temperature dependence of the capacity was investigated. The obtained result is shown in FIG. The larger the absolute value of ΔCap (-40°C/20°C), the greater the temperature dependence of the capacity.

Therefore, from the results shown in Table 2 and FIG. 3, it was judged that it is preferable that the thickness of a conductive polymer layer is 200-2450 nm.

(industrial applicability)

An electrolytic capacitor having a small size and a large capacity was obtained by the present invention.

Claims (7)

A conductive substrate having a foil shape, and a cathode having a conductive polymer layer provided on a surface of the conductive substrate;
an anode comprising a substrate made of a valve metal and having a foil shape, and a dielectric layer made of an oxide of the valve metal provided on the surface of the base, wherein the dielectric layer and the conductive polymer layer of the cathode are disposed to face each other with a space;
An electrolytic capacitor having an ion conductive electrolyte filled in the space,
The conductive polymer layer in the cathode is an electrolytic polymerization film having a thickness in the range of 200 to 2450 nm,
An electrolytic capacitor, characterized in that by applying a voltage between the positive electrode and the negative electrode, the conductive polymer layer of the negative electrode in contact with the ion conductive electrolyte expresses a redox capacity. The method of claim 1,
The conductive substrate in the cathode includes a valve metal foil, an oxide film of a valve metal constituting the valve metal foil provided on the surface of the valve metal foil, and carbon, titanium, platinum, gold, provided on the surface of the oxide film , silver, cobalt, nickel, a base having a conductive film composed of a conductive material selected from the group consisting of iron,
The electrolytic capacitor in which the said conductive polymer layer is provided in the surface of the said conductive film. 3. The method of claim 2,
The electrolytic capacitor wherein the valve metal foil is an aluminum foil. 4. The method of claim 3,
The electrolytic capacitor wherein the conductive film is a titanium-deposited film containing nitrogen or carbon. 5. The method according to any one of claims 1 to 4,
An electrolytic capacitor in which the conductive polymer layer of the negative electrode is made of poly(3,4-ethylenedioxythiophene). A method for manufacturing the electrolytic capacitor of claim 1, comprising:
A cathode forming step of forming a conductive polymer layer with a thickness in the range of 200 to 2450 nm by electrolytic polymerization on the surface of a conductive substrate having a foil shape to obtain a cathode for the electrolytic capacitor;
an anode forming step of oxidizing the surface of a substrate made of a valve metal and having a foil shape to form a dielectric layer made of an oxide of the valve metal to obtain an anode for the electrolytic capacitor; and
and an electrolyte charging step of filling the space with an ion conductive electrolyte by making the conductive polymer layer of the negative electrode and the dielectric layer of the positive electrode face each other with a space therebetween. 7. The method of claim 6,
The conductive substrate used in the cathode forming step includes a valve metal foil, an oxide film of the valve metal constituting the valve metal foil provided on the surface of the valve metal foil, and carbon, titanium, platinum, provided on the surface of the oxide film , gold, silver, cobalt, nickel, a base having a conductive film composed of a conductive material selected from the group consisting of iron,
In the cathode forming step, a method for manufacturing an electrolytic capacitor in which the conductive polymer layer is formed on the surface of the conductive film.

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