阅读说明：本技术 电解电容器及其制造方法 (Electrolytic capacitor and method for manufacturing the same ) 是由 福井齐 于 2018-04-26 设计创作，主要内容包括：电解电容器具备阳极体、在上述阳极体上形成的电介质层、以及在上述衍生物层上形成的固体电解质层。上述固体电解质层包含导电性高分子,上述导电性高分子包含自掺杂型的聚(3,4-乙烯二氧噻吩)类。(The electrolytic capacitor includes an anode body, a dielectric layer formed on the anode body, and a solid electrolyte layer formed on the derivative layer. The solid electrolyte layer contains a conductive polymer, and the conductive polymer contains a self-doping type poly (3, 4-ethylenedioxythiophene).)

1. An electrolytic capacitor comprising an anode body, a dielectric layer formed on the anode body, and a solid electrolyte layer formed on the derivative layer,

the solid electrolyte layer contains a conductive polymer,

the conductive polymer contains self-doping poly (3, 4-ethylenedioxythiophene).

2. The electrolytic capacitor as recited in claim 1, wherein the self-doping type poly (3, 4-ethylenedioxythiophene) has a sulfonic acid group or a salt thereof.

3. The electrolytic capacitor according to claim 1 or 2, wherein the solid electrolyte layer comprises a first conductive polymer layer comprising a first conductive polymer formed on the dielectric layer, and a second conductive polymer layer comprising a second conductive polymer formed on the first conductive polymer layer,

the first conductive polymer is the self-doping type poly (3, 4-ethylenedioxythiophene).

4. The electrolytic capacitor as recited in claim 3, wherein the second conductive polymer is a non-self-doping type conductive polymer.

5. The electrolytic capacitor as recited in claim 3 or 4, wherein the second conductive polymer is polypyrrole.

6. The electrolytic capacitor according to any one of claims 3 to 5, wherein the thickness of the first conductive polymer layer is thinner than the thickness of the second conductive polymer layer.

7. A method of manufacturing an electrolytic capacitor, comprising:

preparing an anode body having a dielectric layer formed thereon; and

a step of forming a solid electrolyte layer containing a self-doping type poly (3, 4-ethylenedioxythiophene) on the dielectric layer,

the step of forming the solid electrolyte layer includes: and a step of forming a first conductive polymer layer containing the self-doped poly (3, 4-ethylenedioxythiophene) compound as a first conductive polymer by attaching a first liquid composition containing the self-doped poly (3, 4-ethylenedioxythiophene) compound to the dielectric layer.

8. The method for manufacturing an electrolytic capacitor according to claim 7, wherein the step of forming the solid electrolyte layer further comprises: and a step of forming the second conductive polymer layer including the second conductive polymer by attaching a second liquid composition including the second conductive polymer or a precursor thereof to the first conductive polymer layer.

Technical Field

An electrolytic capacitor including an anode body, a dielectric layer formed on the anode body, and a solid electrolyte layer formed on the derivative layer and containing a conductive polymer is expected as a capacitor having a small volume, a large capacity, and a small Equivalent Series Resistance (ESR).

Patent document 1 proposes a solid electrolytic capacitor including a conductive polymer layer containing a self-doping type conductive polymer having an isothianaphthene skeleton. Patent document 2 proposes a solid electrolytic capacitor including an amine-containing layer and a conductive polymer layer containing a self-doping type conductive polymer such as polyaniline sulfonic acid or poly (isothianaphthenediyl-sulfonate).

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2007-110074

Patent document 1: international publication No. 2013/081099 single file

Disclosure of Invention

Problems to be solved by the invention

However, the ESR in a high-temperature environment may increase depending on the type of the conductive polymer.

Means for solving the problems

One aspect of the present invention relates to an electrolytic capacitor including an anode body, a dielectric layer formed on the anode body, and a solid electrolyte layer formed on the derivative layer,

the solid electrolyte layer contains a conductive polymer,

the conductive polymer contains self-doping poly (3, 4-ethylenedioxythiophene).

Further, another aspect of the present invention relates to a method for manufacturing an electrolytic capacitor, including:

preparing an anode body having a dielectric layer formed thereon; and

a step of forming a solid electrolyte layer containing a self-doping type poly (3, 4-ethylenedioxythiophene) on the dielectric layer,

the step of forming the solid electrolyte layer includes a step of forming a first conductive polymer layer containing the self-doped poly (3, 4-ethylenedioxythiophene) compound as a first conductive polymer by attaching a first liquid composition containing the self-doped poly (3, 4-ethylenedioxythiophene) compound to the dielectric layer.

Effects of the invention

According to the present invention, an electrolytic capacitor capable of maintaining a low ESR even in a high-temperature environment and a method for manufacturing the same can be provided.

Drawings

Fig. 1 is a schematic cross-sectional view of an electrolytic capacitor according to an embodiment of the present invention.

Detailed Description

[ electrolytic capacitor ]

An electrolytic capacitor according to an embodiment of the present invention includes an anode body, a dielectric layer formed on the anode body, and a solid electrolyte layer formed on the derivative layer.

(solid electrolyte layer)

In this embodiment, the solid electrolyte layer contains a conductive polymer, and the conductive polymer contains a self-doping type poly (3, 4-ethylenedioxythiophene) (first conductive polymer).

The self-doping type conductive polymer (poly (3, 4-ethylenedioxythiophene) and the like) means: a conductive polymer having an anionic group directly or indirectly bonded to a skeleton (e.g., a poly (3, 4-ethylenedioxythiophene) skeleton) of the conductive polymer via a covalent bond. The anionic group of the conductive polymer itself functions as a dopant for the conductive polymer, and is therefore called a self-doping type. Anionic groups include, for example, acidic groups (acid type) or conjugated anionic groups thereof (salt type).

Conventionally, polyaniline having an anionic group, polyisothianaphthene having an anionic group, and the like have been used as self-doping type conductive polymers. However, when an electrolytic capacitor including a solid electrolyte layer containing self-doped polyaniline or self-doped polyisothianaphthene is exposed to a high-temperature environment, the ESR increases. This is considered to be because: in a high-temperature environment, the conductivity of the solid electrolyte layer decreases, or the solid electrolyte layer is cracked to lower the stability of the film shape, or the adhesion at the interface between the layer containing the self-doping type conductive polymer and the layer adjacent thereto decreases.

In contrast, according to the present embodiment, by using the self-doping type poly (3, 4-ethylenedioxythiophene) (first conductive polymer), the increase in ESR in a high-temperature environment can be suppressed as compared with the case of using polyaniline and polyisothianaphthene. This is considered to be because: the skeleton of the first conductive polymer has higher heat resistance than polyaniline and the like, and the first conductive polymer is less likely to deteriorate in a high-temperature environment. By using the first conductive polymer, deterioration of the solid electrolyte layer is suppressed even under a high-temperature environment, and cracking or breaking of the solid electrolyte layer can be suppressed. As a result, it is considered that: since the increase in resistance of the solid electrolyte layer is suppressed and high conductivity can be maintained, the increase in ESR in a high-temperature environment is suppressed. The first conductive polymer is supposed to have low heat resistance because it contains more ether bonds than polyisothianaphthenes. Contrary to this guess, it is considered that the increase in ESR in the high-temperature environment is suppressed in the present embodiment because: since the first conductive polymer contains a large number of ether bonds, high adhesion at the interface between the layer containing the first conductive polymer and the layer adjacent to the layer can be easily maintained.

The first conductive polymer contains, for example, poly (3, 4-ethylenedioxythiophene) having an anionic group. Examples of the anionic group include a sulfonic acid group, a carboxyl group, a phosphoric acid group, a phosphonic acid group, and salts thereof (e.g., salts with inorganic bases and salts with organic bases). The poly (3, 4-ethylenedioxythiophene) may have 1 kind of anionic group, or may have 2 or more kinds of anionic groups. The anionic group is preferably a sulfonic acid group or a salt thereof, and may be a combination of a sulfonic acid group or a salt thereof and an anionic group other than a sulfonic acid group or a salt thereof.

The poly (3, 4-ethylenedioxythiophene) includes homopolymers of 3, 4-Ethylenedioxythiophene (EDOT), copolymers of EDOT and other copolymerizable monomers, and derivatives thereof (e.g., substituted compounds). These polymers having an anionic group and derivatives thereof are first conductive polymers.

The weight average molecular weight of the first conductive polymer is not particularly limited, but is, for example, 1000 or more and 1000000 or less.

The solid electrolyte layer may include a first conductive polymer layer containing a first conductive polymer formed on the dielectric layer, and a second conductive polymer layer containing a second conductive polymer formed on the first conductive polymer layer. The second conductive polymer layer may be a single layer or may be composed of a plurality of layers. When there is a region where the first conductive polymer layer is not formed on the dielectric layer, the second conductive polymer layer may be formed on the dielectric layer in this region.

The first conductive polymer layer may contain a conductive polymer other than the first conductive polymer (for example, a non-self-doping conductive polymer described later), but the content of the first conductive polymer is preferably large. The ratio of the first conductive polymer contained in the first conductive polymer layer to the entire conductive polymer may be, for example, 90 mass% or more, or 100 mass%.

The first conductive polymer has an anionic group, but the first conductive polymer layer may contain a dopant as needed. As dopants, for example, anions and/or polyanions can be used. In the first conductive polymer layer, anions and/or polyanions may form a conductive polymer complex together with the conductive polymer. In the present specification, the conductive polymer composite means: the conductive polymer is doped with anions and/or polyanions, or is bonded with anions, or is bonded with polyanions through anionic groups of the polyanions.

Examples of the anion include, but are not particularly limited to, sulfate ion, nitrate ion, phosphate ion, borate ion, and organic sulfonate ion. The anion may be contained in the first conductive polymer layer in the form of a salt.

The polyanion has an anionic group such as a sulfonic acid group, a carboxyl group, a phosphoric acid group, a phosphonic acid group, or a salt thereof. The polyanion may have one kind of anionic group, or may have two or more kinds. The anionic group is preferably a sulfonic acid group or a salt thereof, and may be a combination of a sulfonic acid group or a salt thereof and an anionic group other than a sulfonic acid group or a salt thereof. Examples of the polyanion include polyvinylsulfonic acid, polystyrenesulfonic acid, polyallylsulfonic acid, polypropylenesulfonic acid, polymethacrylsulfonic acid, poly (2-acrylamido-2-methylpropanesulfonic acid), polyisoprene sulfonic acid, polyacrylic acid, and salts thereof. These may be used alone or in combination of two or more. Further, they may be homopolymers or copolymers of two or more monomers. Among them, polystyrene sulfonic acid (PSS) is preferable.

The weight average molecular weight of the polyanion is, for example, 1000 or more and 1000000 or less.

The content of the dopant in the first conductive polymer layer is, for example, 0 to 40 parts by mass, preferably 0 to 10 parts by mass or 0.1 to 10 parts by mass, relative to 100 parts by mass of the first conductive polymer.

The second conductive polymer is generally a conductive polymer different from the first conductive polymer, and is preferably a non-self-doping conductive polymer. The non-self-doping type conductive polymer refers to: a conductive polymer having no anionic group (specifically, a sulfonic acid group, a carboxyl group, a phosphoric acid group, a phosphonic acid group, and salts thereof) directly or indirectly bonded to the skeleton of the conductive polymer through a covalent bond.

As the non-self-doping type conductive polymer, polypyrrole, polythiophene, polyaniline, and the like are preferable. These may be used alone, two or more of them may be used in combination, or a copolymer of two or more of them may be used. In the present specification, polypyrrole, polythiophene, polyaniline, and the like mean a polymer having polypyrrole, polythiophene, polyaniline, and the like as a basic skeleton, respectively. Accordingly, polypyrrole, polythiophene, polyaniline, and the like can include respective derivatives (substituents having substituents other than anionic groups, and the like). For example, polythiophenes include poly (3, 4-ethylenedioxythiophene) (PEDOT) and the like. Among these, polypyrrole (including its derivatives) is preferable from the viewpoint of achieving both high heat resistance and high moisture resistance.

The weight average molecular weight of the second conductive polymer is not particularly limited, and is, for example, 1000 or more and 1000000 or less. When the second conductive polymer layer is composed of a plurality of layers, the second conductive polymers contained in the respective layers may be the same or different.

The second conductive polymer layer may further contain a dopant. As dopants, for example, anions and/or polyanions are used. The anion and the polyanion may be selected from the ions described for the first conductive polymer layer. In the second conductive polymer layer, anions and polyanions may form a conductive polymer composite together with the conductive polymer.

The thickness of the first conductive polymer layer is preferably smaller than that of the second conductive polymer layer. This is because: it is possible to cover as many regions as possible of the dielectric layer surface formed along the surface of the anode body (specifically, the surface including the inner wall surfaces of the pores and recesses of the anode body) with the first conductive polymer layer, and it is possible to easily obtain high heat resistance and reduce leakage current by forming the second conductive polymer layer having a large thickness.

The thickness of each layer can be confirmed by an electron micrograph of a cross section of the solid electrolyte layer in the thickness direction.

The solid electrolyte layer may further contain an alkali component as necessary. The alkali component may be contained in the first conductive polymer layer and/or the second conductive polymer layer. As the alkali component, an inorganic alkali compound, an organic alkali compound, or the like is used. Examples of the inorganic basic compound include metal hydroxides such as ammonia, sodium hydroxide, and calcium hydroxide. The organic base compound is preferably an amine compound or the like. The amine compound is preferably an aliphatic amine, a cyclic amine, or the like. The alkali component may be used alone or in combination of two or more. In the solid electrolyte layer, the alkali component may form a salt with the conductive polymer and/or the dopant.

The solid electrolyte layer may further contain other components within a range not impairing the effects of the present invention.

(Anode body)

The anode body contains a valve metal, an alloy containing a valve metal, or the like. As the valve metal, for example, aluminum, tantalum, niobium, and titanium are preferably used. The valve-acting metal may be used alone or in combination of two or more. The anode body is obtained by roughening the surface of a base material (foil-shaped or plate-shaped base material or the like) containing a valve metal by, for example, etching. The anode body may be a molded body containing particles of a valve metal or a sintered body thereof. The sintered body has a porous structure. That is, when the anode body is a sintered body, the entire anode body may become porous.

(dielectric layer)

The dielectric layer is formed by anodizing the valve metal on the surface of the anode by chemical conversion treatment or the like. The dielectric layer comprises an oxide of a valve action metal. For example, when tantalum is used as the valve metal, the dielectric layer contains Ta₂O₅When aluminum is used as the valve metal, the dielectric layer contains Al_lO₃. The dielectric layer is not limited to this, and may be any material that functions as a dielectric. When the surface of the anode body is porous, the dielectric layer is formed along the surface of the anode body (including the surface of the pores of the anode body and the inner wall surface of the recess).

Fig. 1 is a sectional view schematically showing the structure of an electrolytic capacitor according to an embodiment of the present invention. As shown in fig. 1, an electrolytic capacitor 1 includes: a capacitor element 2; a resin sealing material 3 for sealing the capacitor element 2; and an anode terminal 4 and a cathode terminal 5 each having at least a part thereof exposed to the outside of the resin sealing material 3. The anode terminal 4 and the cathode terminal 5 may be made of metal such as copper or copper alloy. The resin sealing material 3 has a substantially cubic outer shape, and the electrolytic capacitor 1 also has a substantially cubic outer shape. As a material of the resin sealing material 3, for example, an epoxy resin can be used.

Capacitor element 2 includes anode element 6, dielectric layer 7 covering anode element 6, and cathode portion 8 covering dielectric layer 7. Cathode portion 8 includes solid electrolyte layer 9 covering dielectric layer 7 and cathode lead layer 10 covering solid electrolyte layer 9. The cathode lead layer 10 has a carbon layer 11 and a silver paste layer 12.

Anode element 6 includes a region facing cathode portion 8 and a region not facing cathode portion 8. In the region of the anode body 6 not facing the cathode portion 8, an insulating separation layer 13 is formed in a band-like shape in a portion adjacent to the cathode portion 8 so as to cover the surface of the anode body 6, thereby restricting the contact between the cathode portion 8 and the anode body 6. In a region of anode element 6 not facing cathode portion 8, the other part is electrically connected to anode terminal 4 by welding. Cathode terminal 5 is electrically connected to cathode portion 8 via adhesive layer 14 made of a conductive adhesive.

As the anode element 6, an anode element in which the surface of a base material (such as a foil-shaped or plate-shaped base material) containing a valve metal is roughened can be used. For example, an anode body obtained by roughening the surface of an aluminum foil by etching treatment may be used. The dielectric layer 7 contains, for example, Al₂O₃Such as aluminum oxide.

Principal surfaces 4S and 5S of the anode terminal 4 and the cathode terminal 5 are exposed from the same surface of the resin sealing material 3. The exposed surface is used for solder connection or the like with a substrate (not shown) on which the electrolytic capacitor 1 is to be mounted.

The carbon layer 11 may be formed using a conductive carbon material such as graphite, for example, as long as it has conductivity. For the silver paste layer 12, for example, a composition containing silver powder and a binder resin (epoxy resin or the like) can be used. The structure of the cathode lead layer 10 is not limited to this, and may be any structure having a current collecting function.

The solid electrolyte layer 9 is formed so as to cover the dielectric layer 7. The solid electrolyte layer 9 does not necessarily need to cover the entire (entire) surface of the dielectric layer 7, and may be formed so as to cover at least a part of the dielectric layer 7.

Dielectric layer 7 is formed along the surface of anode element 6 (including the inner wall surface of the hole). The surface of dielectric layer 7 has a concave-convex shape corresponding to the surface shape of anode body 6. The solid electrolyte layer 9 is preferably formed to fill the irregularities of the dielectric layer 7.

The electrolytic capacitor of the present invention is not limited to the electrolytic capacitor having the above-described configuration, and can be applied to electrolytic capacitors having various configurations. Specifically, the present invention can be applied to a wound electrolytic capacitor, an electrolytic capacitor using a sintered body of a metal powder as an anode body, and the like.

[ method for producing electrolytic capacitor ]

The method for manufacturing an electrolytic capacitor according to an embodiment of the present invention includes: a step (first step) of preparing an anode body having a dielectric layer formed thereon; and a step (second step) of forming a solid electrolyte layer containing a first conductive polymer on the dielectric layer. The second process includes: and forming a first conductive polymer layer including the first conductive polymer by adhering a first liquid composition including the first conductive polymer to the dielectric layer. The second process may further include: and a step of forming a second conductive polymer layer containing a second conductive polymer by attaching a second liquid composition containing the second conductive polymer or a precursor thereof to the first conductive polymer layer. The method for manufacturing an electrolytic capacitor may further include a step of preparing an anode body before the first step. In addition, the manufacturing method may further include a step of forming a cathode lead-out layer.

Hereinafter, each step will be described in more detail.

(step of preparing Anode body)

In this step, the anode body is formed by a known method according to the type of the anode body.

The anode body can be prepared by, for example, roughening the surface of a foil-like or plate-like base material containing a valve metal. The roughening may be carried out by forming irregularities on the surface of the substrate, and for example, by etching (for example, electrolytic etching) the surface of the substrate.

Further, a powder of a valve metal is prepared, and the powder is molded into a desired shape (for example, a block shape) in a state where one end side in the longitudinal direction of the anode lead of the rod-shaped body is embedded in the powder, thereby obtaining a molded body. By sintering this molded body, an anode body having a porous structure in which one end of an anode lead is embedded can be formed.

(first step)

In the first step, a dielectric layer is formed on the anode body. The dielectric layer is formed by anodizing the anode body. The anodic oxidation can be performed by a known method, for example, chemical conversion treatment. The formation treatment may be performed as follows: for example, the surface of the anode element is impregnated with the chemical conversion solution by immersing the anode element in the chemical conversion solution, and a voltage is applied between the anode element serving as an anode and a cathode immersed in the chemical conversion solution. As the chemical solution, for example, a phosphoric acid aqueous solution or the like is preferably used.

(second Process)

In the second step, a solid electrolyte layer is formed so as to cover at least a part of the dielectric layer. Since the solid electrolyte layer contains at least the first conductive polymer layer containing the first conductive polymer, at least the first conductive polymer layer is formed in the second step. The first conductive polymer layer is formed using a first liquid composition containing a first conductive polymer. In the second step, after the first conductive polymer layer is formed, a second liquid composition may be attached to the first conductive polymer layer to form a second conductive polymer layer. The manufacturing method according to the present embodiment may include a step of preparing a first liquid composition before the step of forming the first conductive polymer layer. The production method may further include a step of preparing a second liquid composition before the step of forming the second conductive polymer layer.

(Process for preparing the first liquid composition)

In this step, a first liquid composition containing a first conductive polymer and a dispersion medium or solvent is prepared. As the first conductive polymer, the conductive polymers exemplified above can be used. The first liquid composition may contain a polyanion, a base component, and/or further other components as necessary.

The first liquid composition is, for example, a dispersion (solution) of a first conductive polymer. The first liquid composition may include a conductive polymer complex of a first conductive polymer and a polyanion. The average particle diameter of the particles of the conductive polymer (or conductive polymer composite) in the first liquid composition is, for example, 5nm to 800 nm. The average particle diameter of the conductive polymer (or the conductive polymer composite) can be determined from a particle diameter distribution by, for example, a dynamic light scattering method.

Examples of the dispersion medium (solvent) used in the first liquid composition include water, an organic solvent, and a mixture thereof. Examples of the organic solvent include monohydric alcohols such as methanol, ethanol, and propanol; polyhydric alcohols such as ethylene glycol and glycerin; or aprotic polar solvents such as N, N-dimethylformamide, dimethyl sulfoxide, acetonitrile, acetone, and benzonitrile.

The first liquid composition can be obtained by, for example, subjecting a precursor of the first conductive polymer to oxidative polymerization in a dispersion medium (solvent). Examples of the precursor include a monomer constituting the first conductive polymer and/or an oligomer in which a plurality of monomers are linked. The first liquid composition containing the conductive polymer composite can be obtained by subjecting a precursor of the first conductive polymer to oxidative polymerization in a dispersion medium (solvent) in the presence of a dopant.

(Process for Forming first conductive Polymer layer)

The first conductive polymer layer can be formed by attaching a first liquid composition to the dielectric layer. The first conductive polymer layer includes: for example, the step a is a step of immersing the anode body having the dielectric layer formed thereon in the first liquid composition, or a step of applying and dropping the first liquid composition to the anode body having the dielectric layer formed thereon, followed by drying. The step a may be repeated a plurality of times.

(Process for preparing second liquid composition)

The second liquid composition contains a second conductive polymer or a precursor thereof, a dispersion medium (solvent), and a dopant as needed. As the second conductive polymer and the dopant, those exemplified above can be used. Examples of the precursor of the second conductive polymer include a monomer constituting the second conductive polymer and/or an oligomer in which some monomers are linked. As the dispersion medium (solvent), those exemplified for the first liquid composition can be used. The second liquid composition may further comprise a base component and/or other components.

As the second liquid composition, for example, a dispersion (solution) of the second conductive polymer or a dispersion (solution) of a conductive polymer composite of the second conductive polymer and the dopant can be used. The second liquid composition may be prepared according to the case of the first liquid composition.

The second conductive polymer layer can be formed by chemical polymerization or electrolytic polymerization. In the case of chemical polymerization, for example, the second conductive polymer layer is formed using a second liquid composition containing a precursor of the second conductive polymer, a dispersion medium (or a solvent), an oxidizing agent, and if necessary, a dopant. In the case of electrolytic polymerization, for example, the second conductive polymer layer is formed using a second liquid composition containing a precursor of the second conductive polymer, a dispersion medium (or a solvent), and if necessary, a dopant.

(Process for Forming second conductive Polymer layer)

The second conductive polymer layer can be formed by attaching the second liquid composition to the first conductive polymer layer.

When a dispersion (or solution) containing a second conductive polymer is used as the second liquid composition, the step of forming the second conductive polymer layer includes: for example, the step b of immersing the first conductive polymer layer in the second liquid composition, or applying and dropping the second liquid composition to the first conductive polymer layer, followed by drying. The step b may be repeated a plurality of times.

In the case where the second conductive polymer layer is formed by chemical polymerization, the second conductive polymer layer forming step includes: and a step c of immersing the first conductive polymer layer in the second liquid composition, or applying and dropping the second liquid composition to the first conductive polymer layer to adhere the second liquid composition to the first conductive polymer layer, and then heating the resultant. The precursor of the second conductive polymer is polymerized by heating to form a second conductive polymer layer. The step c may be repeated a plurality of times.

In the case of forming the second conductive polymer layer by electrolytic polymerization, the step of forming the second conductive polymer layer includes: and a step of immersing the first conductive polymer layer in the second liquid composition, and supplying power from the supply electrode with the first conductive polymer layer as an electrode. In this step, the precursor of the second conductive polymer is polymerized to form the second conductive polymer layer.

After the chemical polymerization or electrolytic polymerization, a cleaning treatment may be performed as needed.

In order to form the second conductive polymer layer having a sufficient thickness, the average particle diameter of the conductive polymer (or conductive polymer composite) particles used in the second conductive polymer layer may be larger than the average particle diameter of the conductive polymer (or conductive polymer composite) particles used in the first conductive polymer layer. For the same purpose, the second liquid composition may contain a conductive polymer (or conductive polymer composite) having a higher solid content than the first liquid composition. Further, the number of steps b and c can be increased for the same purpose, and the feeding time can be prolonged or the current can be increased in the electrolytic polymerization.

(step of Forming cathode lead-out layer)

In this step, a carbon layer and a silver paste layer are sequentially laminated on the surface (preferably of the formed solid electrolyte layer) of the anode body obtained in the second step, thereby forming a cathode lead layer.