Electrolytic capacitor and method of manufacturing the same

Abstract

To provide a method of manufacturing an electrolytic capacitor which improves conductivity and equivalent series resistance (ESR) of a porous part by coating a large part of a dielectric layer of an anode foil of the electrolytic capacitor with a conductive polymer, and to provide the electrolytic capacitor.SOLUTION: A method of manufacturing an electrolytic capacitor according to the present invention includes the steps of: preparing a fiber structural body; applying a conductive polymer-containing liquid containing a conductive polymer to the fiber structural body; and removing at least a part of the conductive polymer-containing liquid from the fiber structural body after the conductive polymer-containing liquid is applied to the fiber structural body, wherein an electric conductivity of the electrolytic solution at 30 °C. is 3. 0mS / cm or more.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an electrolytic capacitor comprising a conductive polymer as a cathode material and an electrolyte solution, and a method for manufacturing the same. [Background technology]

[0002] Capacitors used in electronic devices are required to have large capacitance and low equivalent series resistance (ESR) in the high frequency range. Electrolytic capacitors that use conductive polymers such as polypyrrole, polythiophene, polyfuran, and polyaniline as solid electrolytes are promising capacitors with large capacitance and low ESR.

[0003] Conventionally, the electrolytic capacitor is produced by impregnating a capacitor element with a dispersion containing a conductive polymer, because it does not require large equipment and the conductive polymer can be applied in the same manner as an electrolyte solution.

[0004] The most effective way to reduce ESR is to incorporate a conductive polymer into the separator. However, when a dispersion containing a conductive polymer is impregnated into a capacitor element, a large amount of the conductive polymer adheres to elements other than the separator, resulting in a large amount of conductive polymer being used and higher manufacturing costs. In other words, the conductive polymer cannot be efficiently attached to the necessary parts of the capacitor element, which is not cost-effective.

[0005] Therefore, Patent Document 1 proposes a method for producing an electrolytic capacitor using a separator to which a conductive polymer has been previously attached. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-207573 Summary of the Invention [Problem to be solved by the invention]

[0007] However, if the conductive polymer is attached only to the separator, most of the dielectric layer of the anode foil will not be covered with the conductive polymer, resulting in insufficient conductivity in the porous parts and insufficient current being drawn, ultimately making it difficult to achieve a low ESR. [Means for solving the problem]

[0008] A first aspect of the present invention relates to a method for manufacturing an electrolytic capacitor, the method comprising the steps of: preparing an anode foil, a cathode foil, and a fiber structure each having a porous portion with a dielectric layer; preparing a conductive polymer-containing liquid containing a conductive polymer component and a first solvent; applying the conductive polymer-containing liquid to the fiber structure and then removing at least a portion of the first solvent to form a separator; fabricating a capacitor element using the anode foil, the separator, and the cathode foil; and impregnating the capacitor element with an electrolyte solution, wherein the electrolyte solution has an electrical conductivity of 3.0 mS / cm or more at 30°C.

[0009] A second aspect of the present invention relates to an electrolytic capacitor manufactured by the above manufacturing method. [Effects of the Invention]

[0010] According to the present invention, in an electrolytic capacitor comprising a conductive polymer and an electrolyte solution as cathode materials, the amount of conductive polymer used can be reduced and a low ESR can be achieved. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a flowchart illustrating an example of a manufacturing method according to an embodiment of the present invention. [Figure 2] 1 is a side view schematically showing an electrolytic capacitor according to an embodiment of the present invention; [Figure 3] FIG. 2 is an exploded perspective view schematically showing a portion of the capacitor element according to the embodiment of the present invention. [Figure 4]1 is a graph showing the relationship between the ESR of an electrolytic capacitor and the electrical conductivity of an electrolyte. DETAILED DESCRIPTION OF THE INVENTION

[0012] The method for manufacturing an electrolytic capacitor according to the present disclosure includes: (i) forming a porous portion having a dielectric layer; (ii) preparing a conductive polymer-containing solution containing a conductive polymer component and a first solvent; and (iii) applying a conductive polymer-containing solution to the fiber structure. (iv) a step of fabricating a separator by removing at least a portion of the first solvent after applying the liquid; and (v) a step of fabricating a capacitor element using the anode foil, the separator, and the cathode foil. ) impregnating the capacitor element with an electrolyte solution, wherein the electrolyte solution has an electrical conductivity of 3.0 mS / cm or more at 30°C.

[0013] Hereinafter, an electrolytic capacitor comprising a conductive polymer and an electrolyte solution will also be referred to as a "hybrid electrolytic capacitor."

[0014] In the above manufacturing method, the step of impregnating the capacitor element with a conductive polymer corresponds to step (iii), which includes applying a conductive polymer-containing liquid to a fiber structure. Then, step (iv) is performed to fabricate a capacitor element using an anode foil, a separator, and a cathode foil. After the capacitor element is fabricated, no further process of impregnating the capacitor element with a conductive polymer component is required. For example, there is no need to impregnate the capacitor element with a conductive polymer-containing liquid, and such a step is usually not performed.

[0015] When the process of impregnating the capacitor element with a conductive polymer-containing liquid is not performed, the adhesion of a large amount of conductive polymer to elements other than the separator is prevented. As a result, the conductive polymer component can be efficiently attached to the separator, where the conductive polymer component is expected to have the greatest effect in reducing ESR. Efficient use of the conductive polymer allows for a reduction in its amount, thereby reducing manufacturing costs.

[0016] The above manufacturing method does not involve a step of actively impregnating the anode foil with a conductive polymer component, so the conductive polymer component cannot be expected to penetrate deep into the porous portion of the anode foil. While some of the conductive polymer component may migrate from the separator to the surface of the porous portion, most of the dielectric layer deeper than the surface is not covered with the conductive polymer component. In this structure, when using an electrolyte with a conductivity comparable to that typically used in hybrid electrolytic capacitors, it becomes difficult to draw sufficient current from the dielectric layer in the porous portion, ultimately resulting in an increase in ESR.

[0017] In hybrid electrolytic capacitors, the effect of the electrolyte's conductivity on the ESR is small, and the approach of improving the electrolyte's conductivity to reduce the ESR is generally considered ineffective.

[0018] In contrast, in hybrid electrolytic capacitors, where the dielectric layer is not easily covered with conductive polymer components deep in the porous portion, when an electrolyte with an electrical conductivity of 3.0 mS / cm or higher at 30°C is used, the ESR is significantly reduced, making it possible to draw sufficient current from the porous portion.

[0019] The function required of the electrolyte used in hybrid electrolytic capacitors is the ability to repair the dielectric layer. This function can be achieved even with an electrolyte that has almost no conductivity. Furthermore, in typical hybrid electrolytic capacitors, the effect of the electrolyte's electrical conductivity on the ESR is very small. For these reasons, the electrical conductivity of the electrolyte used in hybrid electrolytic capacitors has traditionally been set significantly lower than 3.0 mS / cm. In other words, an electrolyte with an electrical conductivity of 3.0 mS / cm or higher can be said to have a significantly high electrical conductivity.

[0020] In a typical hybrid electrolytic capacitor, after assembling a capacitor element including an anode foil, a process is performed in which the capacitor element is impregnated with a conductive polymer component. In this case, the conductive polymer component penetrates deep into the porous portion of the anode foil, and the dielectric layer formed in the deep pits can be coated with the conductive polymer component. While this structure is desirable from the perspective of current extraction, the area coated with the conductive polymer component tends to have a high leakage current (LC) because the dielectric layer is less likely to be repaired by the electrolyte in the area coated with the conductive polymer component. The manufacturing method according to the present disclosure can manufacture an electrolytic capacitor without the conductive polymer component penetrating deep into the porous portion of the anode foil, and is therefore very effective in obtaining an electrolytic capacitor with reduced LC.

[0021] The present disclosure also encompasses an electrolytic capacitor manufactured by the above manufacturing method (hereinafter also referred to as electrolytic capacitor X). Electrolytic capacitor X is an electrolytic capacitor with a good ESR and a reduced LC, and is therefore particularly advantageous over conventional aluminum electrolytic capacitors that do not contain a conductive polymer component but contain an electrolyte solution. Therefore, it is particularly useful in applications where conventional aluminum electrolytic capacitors are used.

[0022] A capacitor element generally includes an anode lead connected to an anode foil and a cathode lead connected to a cathode foil. A capacitor element is typically constructed by winding an anode foil having an anode lead and a cathode foil having a cathode lead, with a separator interposed therebetween. Because the anode lead and the cathode lead must be extended to the outside of the case of the electrolytic capacitor, the anode lead and the cathode lead each have a region that protrudes from the separator. When a conductive polymer-containing liquid is impregnated into the capacitor element, the conductive polymer component adheres to the regions of the anode lead and the cathode lead that protrude from the separator. The conductive polymer component also adheres to the end surfaces of the anode foil and the cathode foil.

[0023] On the other hand, if the process of impregnating the capacitor element with a conductive polymer-containing liquid is not performed, the chances of the conductive polymer component adhering to the areas of the anode and cathode leads that protrude from the separator are significantly reduced. Similarly, the chances of the conductive polymer component adhering to the end surfaces of the anode and cathode foils are also significantly reduced. For example, it is possible that the conductive polymer component peeled off from the separator may float in the electrolyte and then adhere to the areas of the leads that protrude from the separator or to the end surfaces of the anode and cathode foils. However, the amount of conductive polymer component that flows out of the separator is small. Therefore, whether or not the conductive polymer component originates from the separator can be determined from the amount of adhesion to the areas of the leads that protrude from the separator or the end surfaces of the anode and cathode foils, the state of the conductive polymer component (e.g., distribution state), etc.

[0024] In other words, in the case of electrolytic capacitor X, the areas of the anode lead and the cathode lead that protrude from the separator may not be substantially coated with the conductive polymer component. Similarly, the end faces of the anode foil and the cathode foil included in the capacitor element may not be substantially coated with the conductive polymer component. At least from this perspective, it is possible to determine whether electrolytic capacitor X is obtained by the manufacturing method according to the present disclosure.

[0025] Considering variations in the size of the capacitor element, the amount of conductive polymer component used, the manufacturing process, and so on, there are also variations in the area of ​​the lead that protrudes from the separator, the amount of conductive polymer component attached to the end face of the anode foil or cathode foil, and the state of the conductive polymer component. Therefore, it is difficult to clearly define the amount and state of the conductive polymer component attached to the relevant area using parameters. However, the percentage of the area of ​​the area covered by the conductive polymer component on at least one of the end faces of the anode foil and the cathode foil of electrolytic capacitor X can be, for example, 1.0% or less. The percentage of the area of ​​the area covered by the conductive polymer component can be calculated from the image data, for example, by analyzing the end face with an X-ray microanalyzer (XMA) and obtaining elemental mapping image data.

[0026] The mass Mp of the conductive polymer component carried by the anode foil of electrolytic capacitor X and the mass Ms of the conductive polymer component carried by the separator are usually significantly different. For example, Ms > Mp is satisfied, and it is preferable that Ms > 10.0 × Mp is satisfied. Typically, the void volume of the porous portion of the anode foil is larger than the void volume of the separator. Therefore, when a process of impregnating a capacitor element with a conductive polymer-containing liquid is performed as in the conventional case, the amount of conductive polymer carried by the anode foil is greater than the amount carried by the separator. In contrast, when the ESR is sufficiently reduced when Ms > Mp is satisfied, it can be said that the effective utilization rate of the conductive polymer is increased.

[0027] Here, Ms and Mp can be determined as the change in mass before and after combustion by disassembling the electrolytic capacitor, recovering the separator and anode foil, and burning the dry separator and anode foil. For example, Ms and Mp can be calculated by analyzing the separator and anode foil using thermogravimetric analysis (TGA). The TGA method measures, for example, the thermal change and sample loss when the temperature of a sample is increased at a constant rate. Based on these measurements, the mass of the conductive polymer component attached to the separator or anode foil can be calculated. Alternatively, the conductive polymer component may be separated and recovered from the separator using a method such as solvent extraction, and its mass may be measured.

[0028] When the thickness of the porous portion of the anode foil is T, the amount of conductive polymer component M1 present in the region from the surface of the porous portion to a depth D1 of T / 10 and the amount of conductive polymer component M2 present in the region from the depth D1 to a depth D2 of 2T / 10 from the surface of the porous portion preferably satisfy the relationship M1 > M2. It is even more preferable that M1 > 10.0 × M2. Here, M1 and M2 can be calculated from the image data obtained by analyzing a cross section of the anode foil in the thickness direction using X-ray microanalysis and obtaining elemental mapping image data.

[0029] Furthermore, when the thickness of the porous portion is T, the conductive polymer component may be substantially absent in a region deeper than a depth D3, which is T / 2 from the surface of the porous portion. The presence or absence of the conductive polymer component in a region deeper than the depth D3 can be confirmed by analyzing a cross section of the anode foil in the thickness direction by XMA.

[0030] [Manufacturing method of electrolytic capacitors] FIG. 1 is a flowchart showing an example of a method for manufacturing an electrolytic capacitor. Hereinafter, each step of the example of the method for manufacturing an electrolytic capacitor will be described. The manufacturing method includes: (i) forming a dielectric layer; (ii) preparing an anode foil, a cathode foil, and a fiber structure having a porous portion; (iii) preparing a conductive polymer-containing solution containing a conductive polymer component and a first solvent; and (iv) dissolving the conductive polymer component in the fiber structure. (iv) a step of applying a conductive polymer-containing liquid to the structure and then removing at least a portion of the first solvent to form a separator, (iv) a step of fabricating a capacitor element using the anode foil, the separator, and the cathode foil, and (v) a step of impregnating the capacitor element with an electrolytic solution, provided that: The electrolytic solution has an electrical conductivity of 3.0 mS / cm or more at 30°C.

[0031] (i) Step (S1) of preparing an anode foil, a cathode foil, and a fiber structure (ii) Anode foil As a raw material for the anode foil, for example, a metal foil containing a valve metal is prepared. The metal foil used as the anode foil has a porous portion. The porous portion may be formed, for example, by roughening the surface of the metal foil. By roughening, a plurality of projections and depressions are formed on the surface of the metal foil. For example, the metal foil can be roughened by etching the metal foil. The etching may be performed, for example, by direct current electrolysis or alternating current electrolysis.

[0032] Next, a dielectric layer is formed on the surface of the metal foil having a porous portion. The method for forming the dielectric layer is not particularly limited, but the metal foil having a porous portion may be subjected to a chemical conversion treatment. In the chemical conversion treatment, for example, the metal foil is immersed in a chemical conversion solution such as an ammonium adipate solution. Then, the metal foil may be heat-treated, or a voltage may be applied to the metal foil. This forms a chemical conversion coating as the dielectric layer. In this case, the dielectric layer may contain an oxide of a valve metal. However, the dielectric layer is not limited to this, and may be any layer that functions as a dielectric.

[0033] The valve metal may be at least one of titanium, tantalum, aluminum, niobium, etc. The anode foil may contain the valve metal in the form of an alloy containing the valve metal or a compound containing the valve metal.

[0034] (i-ii) Cathode foil The cathode foil is not particularly limited as long as it functions as a cathode. The cathode foil may be a metal foil. The type of metal is not particularly limited, and like the anode foil, it may be a valve metal or an alloy containing a valve metal.

[0035] For example, a metal foil containing a valve metal is prepared as the raw material for the cathode foil. The surface of the cathode foil may be roughened as needed. A dielectric layer (chemical conversion coating) may also be formed on the surface of the metal foil used as the cathode foil.

[0036] A conductive coating layer may be formed on the surface of the cathode foil by sputtering or vapor deposition. This reduces the contact resistance between the cathode foil and the conductive polymer component contained in the separator, which is advantageous for lowering the ESR. The material for forming the conductive coating layer is preferably carbon or a metal (e.g., titanium or nickel) with a lower ionization tendency than the valve metal (e.g., aluminum) that constitutes the cathode foil. Among these, titanium is preferably included in the material for forming the conductive coating layer. Titanium is stable and easily passivated (forms an oxide film) on the surface, and can improve the acid resistance of the cathode foil even when the electrolyte contains a large amount of acidic components.

[0037] Alternatively, an oxide coating layer may be formed on the surface of the cathode foil by chemical conversion. When the electrolyte contains a large amount of acid, it is preferable to form the oxide coating layer at a chemical conversion voltage of 5 V or more in order to improve acid resistance. This makes it easier to improve acid resistance even when the electrolyte contains a large amount of acid.

[0038] After forming a conductive coating layer on the surface of the cathode foil, a portion of the conductive coating layer may be chemically converted to form an oxide coating layer. Metals contained in the conductive coating layer include nickel, titanium, tantalum, and zirconium. Titanium, which has a high oxide dielectric constant, is particularly preferred from the viewpoint of increasing the combined capacitance of the anode foil and the cathode foil. In this case, to improve acid resistance, it is preferable to form the oxide coating on the surface of the conductive coating layer at a chemical conversion voltage of 2 V or more, more preferably 4 V or more.

[0039] After forming an oxide coating layer on the surface of the cathode foil, a conductive coating layer may be further formed on the oxide coating layer. In this case, if the electrolyte contains a large amount of acid, it is preferable to form the oxide coating on the surface of the cathode foil at a chemical conversion voltage of 5 V or more. In this case, titanium is preferable as the valve metal contained in the conductive coating layer.

[0040] The conductive coating layer can be formed by attaching a conductive inorganic material to the surface of the cathode foil. A gas-phase method may be used. Examples of gas-phase methods include chemical vapor deposition, vacuum deposition, sputtering, and ion plating. The gas-phase method is suitable for forming a conductive coating layer containing a deposited film of an inorganic material. For example, a conductive coating layer containing a metal nitride can be formed by the gas-phase method under a nitrogen gas atmosphere. Preferred inorganic materials for forming the deposited film include conductive carbon such as amorphous carbon, titanium, and the like. Examples of raw materials for the conductive carbon include graphite, hard carbon, soft carbon, and carbon black.

[0041] The conductive coating layer may be formed by applying a paste or slurry containing a conductive inorganic material and a binder to the surface of the cathode foil to form a coating film, and then drying the coating film. In this case, the binder may be removed by heat treatment of the coating film.

[0042] The thickness of the coating layer may be, for example, 5 nm or more and 200 nm or less, or 10 nm or more and 200 nm or less. The thickness of the coating layer can be measured by, for example, X-ray photoelectron spectroscopy (XPS method).

[0043] (i-iii) Fiber structure The fibrous structure is the raw material for the separator. The fibrous structure is not particularly limited as long as it is porous. Examples of the fibrous structure include woven fabrics, knitted fabrics, and nonwoven fabrics containing fibers. Cellulose, which is low-cost and retains electrolyte well, can be used as the fibrous structure. However, since cellulose tends to wrinkle immediately upon contact with a conductive polymer-containing liquid and shrink upon drying, a fibrous structure containing 50% by mass or more of synthetic fibers may be used. Alternatively, a fibrous structure containing a paper strength agent in addition to cellulose fibers may be used. By suppressing wrinkling of the separator, the conductive polymer-containing liquid adheres uniformly, resulting in a uniform thickness of the resulting separator. Therefore, variations in the withstand voltage and inter-electrode resistance of electrolytic capacitors are likely to be suppressed.

[0044] In a fiber structure containing 50% by mass or more of synthetic fibers (hereinafter referred to as a first fiber structure), the content of synthetic fibers may be 70% by mass or more of the fiber structure. The type of synthetic fiber is not particularly limited. In terms of strength and resistance to swelling with water, the synthetic fiber may include at least one type selected from the group consisting of nylon fiber, aramid fiber, acrylic fiber, and polyester fiber.

[0045] The first fibrous structure may contain cellulose. In consideration of electrolyte retention, the cellulose content may be 10% by mass or more of the fibrous structure. The cellulose content may be less than 50% by mass, 30% by mass or less, or 20% by mass or less.

[0046] In a fiber structure containing a paper strength agent together with cellulose fibers (hereinafter referred to as the second fiber structure), the type of paper strength agent is not particularly limited and may be a wet strength agent and / or a dry strength agent. These may be used alone or in combination. Examples of wet strength agents include at least one selected from the group consisting of urea-formaldehyde resin, melamine-formaldehyde resin, polyamide-polyamine epichlorohydrin, and polyvinylamine. Examples of dry strength agents include at least one selected from the group consisting of polyacrylamide, polyvinyl alcohol, starch, and carboxymethyl cellulose.

[0047] The paper strength agent may be added to the raw material of the second fibrous structure (for example, a slurry containing cellulose fibers), or may be applied to the second fibrous structure by spraying or the like.

[0048] When a paper strength agent is added, the second fibrous structure may contain cellulose in an amount of 40% by mass or more, or 70% by mass or more. The second fibrous structure may further contain synthetic fibers. The content of the synthetic fibers may be, for example, 10% by mass or more and 60% by mass or less of the second fibrous structure.

[0049] The density of each fiber structure is, for example, 0.2 g / cm 3 More than 0.45g / cm 3 Even in the case of a fiber structure having such a low density, if the fiber structure contains 50% by mass or more of synthetic fibers or contains a paper strength agent together with cellulose fibers, swelling of the fiber structure due to the conductive polymer component-containing liquid is likely to be suppressed. The density of the fiber structure (including the paper strength agent) is, for example, 0.25 g / cm 3 More than 0.40g / cm 3 It may be the following:

[0050] The thickness of each fiber structure is not particularly limited. The thickness of each fiber structure may be, for example, 20 μm or more and 100 μm or less, and preferably 30 μm or more and 60 μm or less. This makes it easier to prevent short circuits in the resulting electrolytic capacitor and to further improve the ESR reduction effect.

[0051] (ii) Step (S2) of preparing a conductive polymer-containing liquid The conductive polymer-containing liquid contains a first solvent and a conductive polymer component. The conductive polymer-containing liquid can be obtained, for example, by dispersing particles of the conductive polymer component in the first solvent, or by polymerizing a precursor monomer of the conductive polymer component in the first solvent to generate particles of the conductive polymer component in the first solvent.

[0052] The content of the conductive polymer component in the conductive polymer-containing liquid is not particularly limited. The conductive polymer component may be contained in the conductive polymer-containing liquid in an amount of 1% by mass or more and 15% by mass or less. When the content of the conductive polymer component is within this range, it becomes easy to attach a sufficient amount of the conductive polymer component to the fiber structure. In order to make it easier for even more of the conductive polymer component to be attached to the fiber structure, the content of the conductive polymer component may be 3% by mass or more.

[0053] The viscosity of the conductive polymer-containing liquid is not particularly limited. The viscosity of the conductive polymer-containing liquid measured at room temperature (20°C) using a vibration viscometer (for example, VM-100A manufactured by Sekonic Corporation) may be 10 mPa·s or more. The viscosity of the conductive polymer-containing liquid measured under the above conditions may be 40 mPa·s or more, or 50 mPa·s or more, or may be 200 mPa·s or less. A conductive polymer-containing liquid having a viscosity in this range is particularly suitable for coating methods.

[0054] The conductive polymer component includes a conductive polymer. Examples of the conductive polymer include polypyrrole, polythiophene, polyfuran, polyaniline, polyacetylene, polyphenylene, polyphenylene vinylene, polyacene, and polythiophene vinylene. These may be used alone or in combination of two or more kinds, or may be copolymers of two or more kinds of monomers.

[0055] In this specification, polypyrrole, polythiophene, polyfuran, polyaniline, etc. refer to polymers having polypyrrole, polythiophene, polyfuran, polyaniline, etc. as their basic skeletons, respectively. Therefore, polypyrrole, polythiophene, polyfuran, polyaniline, etc. may also include their respective derivatives. For example, polythiophene includes poly(3,4-ethylenedioxythiophene).

[0056] The conductive polymer component may further contain a dopant. The dopant may be a polyanion. Specific examples of polyanions include polyvinyl sulfonic acid, polystyrene sulfonic acid, polyallylsulfonic acid, polyacrylic sulfonic acid, polymethacrylic sulfonic acid, poly(2-acrylamido-2-methylpropanesulfonic acid), polyisoprene sulfonic acid, and polyacrylic acid. These may be used alone or in combination of two or more. Furthermore, these may be polymers of a single monomer or copolymers of two or more monomers. Among these, polyanions derived from polystyrene sulfonic acid are preferred.

[0057] The weight-average molecular weight of the polyanion contained in the conductive polymer component is not particularly limited. The weight-average molecular weight of the first polyanion may be, for example, 1,000 or more and 200,000 or less. A conductive polymer component containing such a polyanion is likely to be uniformly dispersed in the first solvent and to adhere to the separator. The weight-average molecular weight of the polyanion may be 1,000 or more and 70,000 or less. Even when a large amount of such a polyanion is contained, an excessive increase in viscosity of the conductive polymer-containing liquid is suppressed, and the amount of the conductive polymer adhering to the separator is likely to increase.

[0058] The conductive polymer component is dispersed in the first solvent, for example, in the form of particles. The average particle size of the conductive polymer component particles is not particularly limited and can be appropriately adjusted depending on the polymerization conditions, dispersion conditions, etc. For example, the average particle size of the conductive polymer component particles may be 0.01 μm or more and 0.5 μm or less. Here, the average particle size is the median diameter in the volume particle size distribution measured with a particle size analyzer using dynamic light scattering.

[0059] The first solvent may contain water or a non-aqueous solvent. A non-aqueous solvent is a general term for liquids other than water, including organic solvents and ionic liquids. Water may account for 50% by mass or more of the first solvent, 70% by mass or more, or 90% by mass or more. Examples of non-aqueous solvents used together with water include polar solvents (protic solvents and / or aprotic solvents).

[0060] Examples of protic solvents include alcohols such as methanol, ethanol, propanol, butanol, ethylene glycol (EG), propylene glycol, polyethylene glycol (PEG), diethylene glycol monobutyl ether, glycerin, 1-propanol, butanol, polyglycerin, sorbitol, mannitol, and pentaerythritol, and formaldehyde. Examples of aprotic solvents include amides such as N-methylacetamide, N,N-dimethylformamide, and N-methyl-2-pyrrolidone, esters such as methyl acetate and γ-butyrolactone (γBL), ketones such as methyl ethyl ketone, ethers such as 1,4-dioxane, sulfur-containing compounds such as dimethyl sulfoxide and sulfolane (SL), and carbonate compounds such as propylene carbonate.

[0061] When the first solvent contains the above-mentioned alcohols (particularly polyhydric alcohols and sugar alcohols), the electrical conductivity and the separator impregnation are likely to be increased. On the other hand, polyhydric alcohols and sugar alcohols tend to swell cellulose. The first and second fiber structures are also unlikely to swell in the first solvent containing such alcohols, and therefore wrinkles are suppressed.

[0062] (iii) Step (S3) of preparing a separator Next, the conductive polymer-containing liquid is applied to the fiber structure, and then at least a part of the first solvent is removed to produce a separator. From the viewpoint of improving the efficiency of the subsequent process of impregnating the capacitor element with the electrolyte solution, the separator may be maintained in a state containing the first solvent (i.e., in a wet state) during the period from when the conductive polymer-containing liquid is applied to the fiber structure to when the capacitor element is impregnated with the electrolyte solution.

[0063] By applying a conductive polymer-containing liquid to the fiber structure, which is the raw material for the separator, before fabricating the capacitor element, the conductive polymer component can be selectively contained in the separator, and the adhesion of a large amount of conductive polymer to elements other than the separator can be prevented. The conductive polymer component is mainly attached to the surface of the fibers that make up the fiber structure.

[0064] The method for applying the conductive polymer-containing liquid to the fiber structure is not particularly limited. The fiber structure may be impregnated with the conductive polymer-containing liquid, or the conductive polymer-containing liquid may be applied to the fiber structure by a coating method.

[0065] The coating method is a technique for applying a liquid substance to an object using a coater, such as a gravure coater, knife coater, comma coater, roll coater, die coater, or lip coater.

[0066] The amount of the conductive polymer-containing liquid applied to the fiber structure is not particularly limited. For example, the amount of the conductive polymer-containing liquid applied to the fiber structure is 0.02 mg / cm. 2More than 0.2mg / cm 2 Below that, 0.03 mg / cm 2 More than 0.1mg / cm 2 The conditions may be appropriately set so that the following conductive polymer component adheres.

[0067] The coating treatment with the conductive polymer-containing liquid may be performed on one or both sides of the fiber structure. The coating treatment with the conductive polymer-containing liquid may be performed multiple times on the same side of the fiber structure. This increases the amount of conductive polymer component that adheres. In this case, the drying treatment may be performed after multiple coating treatments are performed consecutively, or after each coating treatment.

[0068] When the separator is viewed from the normal direction of its main surface, for example, 50% or more of the area of ​​the main surface may be covered with the conductive polymer component. The area coverage by the conductive polymer component may be 60% or more, preferably 90% or more. The conductive polymer component may be disposed continuously or discontinuously on the surface of the separator. The area coverage is calculated using a separator cut to a predetermined size used in an electrolytic capacitor. The area coverage may be calculated by binarizing an image of the main surface of the component.

[0069] From the viewpoint of mass productivity, the process for producing a separator may be performed on a long fiber structure. When coating both sides of a long fiber structure, the coating is first performed on one side, followed by drying, and then the fiber structure is wound up on a roll. Then, while the fiber structure is unwound from the roll in a reversed direction, the other side is coated again using the same or a different coater.

[0070] The conductive polymer component may also be attached to components other than the separator of the capacitor element. For example, if the conductive polymer component is attached to the cathode foil, the self-repairing ability of the anode foil will not be impaired.

[0071] The first solvent is removed by a drying treatment such as heat drying or reduced pressure drying. The drying treatment is not particularly limited and may be appropriately set depending on the type of the first solvent, the amount of application, etc. In this case, the drying treatment may be performed to an extent that the first solvent is not completely removed.

[0072] When the capacitor element is impregnated with an electrolyte in a later process, if the conductive polymer component adheres to the separator along with the first solvent, the electrolyte is guided by the first solvent and easily penetrates into the separator's pores. This facilitates contact between the anode foil and cathode foil and the electrolyte, which is expected to improve the self-repairing performance of the anode foil and increase capacitance. Furthermore, when a long separator with the conductive polymer component adhered thereto is wound into a roll, the conductive polymer component is less likely to crack.

[0073] The long separator with the conductive polymer component attached thereto is cut before or during the process of fabricating the capacitor element, as are the other long components.

[0074] (iv) Step (S4) of producing a capacitor element A capacitor element can be obtained by stacking or rolling the anode foil and the cathode foil with a separator between them. In the case of a rolled capacitor element, the end of the cathode foil located on the outermost layer is fixed with a stop tape. If the anode foil has cut surfaces, the capacitor element may be further subjected to chemical conversion treatment (re-chemical conversion treatment) to form a dielectric layer on the cut surfaces.

[0075] (v) Step (S5) of impregnating the capacitor element with an electrolyte Next, the capacitor element is impregnated with the electrolytic solution. The method for impregnating the electrolytic solution is not particularly limited. At this time, the capacitor element may be impregnated with the electrolytic solution while the separator contains the first solvent. For example, it is desirable that the first solvent remains in an amount of 10 mass % or less relative to the amount contained in the conductive polymer-containing liquid immediately after the coating process.

[0076] The electrical conductivity of the electrolyte at 30°C may be 3.0 mS / cm or higher, but may also be 5.0 mS / cm or higher, or even 10 mS / cm or higher. Since it is difficult to increase the electrical conductivity of the electrolyte at 30°C above 100 mS / cm, 100 mS / cm can be considered the upper limit. The electrical conductivity of the electrolyte can be measured by immersing a container containing the electrolyte in a water bath to maintain the electrolyte at 30°C and using a commercially available electrical conductivity meter (e.g., EC METER CM-30R manufactured by TOA-DKK). The electrical conductivity can be measured by immersing a specified probe of the electrical conductivity meter in the electrolyte.

[0077] The electrolytic solution contains a second solvent and a solute. From the viewpoint of achieving the above-mentioned electrical conductivity, the electrolytic solution may contain 10% by mass or more of the solute, and further 20% by mass or more. As the solute, a salt of an acid component and a base component that ionically dissociates in the electrolytic solution is preferred because it has a high degree of dissociation. Since many conductive polymer components are stable in acidic electrolytic solutions, the acid component may be in excess. However, from the viewpoint of increasing the electrical conductivity of the electrolytic solution, it is most desirable to contain 1 equivalent of the base component per equivalent of the acid component in the electrolytic solution, and 0.8 equivalents or more and 1.2 equivalents or less of the base component per equivalent of the acid component may also be contained.

[0078] From the above, the pH of the electrolytic solution is preferably 5.0 or higher, and may be 7.0 or higher. However, from the viewpoint of preventing deterioration of the conductive polymer component, the pH of the electrolytic solution is desirably 8.5 or lower.

[0079] The acid component is preferably one that does not excessively increase the viscosity of the electrolyte, easily dissociates in the electrolyte, and generates anions that are easily mobile in the second solvent. Examples of such acid components include aliphatic sulfonic acids having 1 to 30 carbon atoms and aromatic sulfonic acids having 6 to 30 carbon atoms. Among aliphatic sulfonic acids, monovalent saturated aliphatic sulfonic acids (e.g., hexanesulfonic acid) are preferred. Among aromatic sulfonic acids, aromatic sulfonic acids having a hydroxy group or a carboxy group in addition to a sulfo group are preferred, specifically, oxyaromatic sulfonic acids (e.g., phenol-2-sulfonic acid) and sulfoaromatic carboxylic acids (e.g., p-sulfobenzoic acid, 3-sulfophthalic acid, 5-sulfosalicylic acid) are preferred.

[0080] Examples of other acid components include carboxylic acids. The carboxylic acid preferably includes an aromatic carboxylic acid (aromatic dicarboxylic acid) having two or more carboxyl groups. Examples of aromatic carboxylic acids include phthalic acid (ortho-isomer), isophthalic acid (meta-isomer), terephthalic acid (para-isomer), maleic acid, benzoic acid, salicylic acid, trimellitic acid, and pyromellitic acid. Among these, aromatic dicarboxylic acids such as phthalic acid (ortho-isomer) and maleic acid are more preferred. The carboxyl groups of aromatic dicarboxylic acids are stable and do not easily cause side reactions. Therefore, they exhibit the effect of stabilizing the conductive polymer component over a long period of time, which is advantageous for extending the life of the electrolytic capacitor. The carboxylic acid may also be an aliphatic carboxylic acid such as adipic acid.

[0081] The acid component may contain a complex compound of an organic acid and an inorganic acid from the viewpoint of thermal stability. Examples of the complex compound of an organic acid and an inorganic acid include borodisalicylic acid, borodioxalic acid, and borodiglycolic acid, which have high heat resistance.

[0082] The acid component may include inorganic acids such as boric acid, phosphoric acid, phosphorous acid, hypophosphorous acid, and phosphonic acid.

[0083] The concentration of the acid component contained in the electrolytic solution may be 5% by mass or more and 50% by mass or less, or may be 15% by mass or more and 35% by mass or less.

[0084] The base component is expected to promote dissociation of the acid component and also inhibit corrosion of the electrode foil. The base component is not particularly limited, but examples thereof include ammonia, primary amines, secondary amines, tertiary amines, quaternary ammonium compounds, and amidinium compounds. Examples of the amines include aliphatic amines, aromatic amines, and heterocyclic amines.

[0085] The concentration of the base component contained in the electrolytic solution may be 5% by mass or more and 50% by mass or less, or may be 10% by mass or more and 35% by mass or less.

[0086] Examples of the second solvent include water, sulfone compounds, lactone compounds, carbonate compounds, polyhydric alcohols, etc. Examples of sulfone compounds include sulfolane, dimethyl sulfoxide, and diethyl sulfoxide. Examples of lactone compounds include γ-butyrolactone and γ-valerolactone. Examples of carbonate compounds include dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), ethylene carbonate (EC), propylene carbonate (PC), and fluoroethylene carbonate (FEC). Examples of polyhydric alcohols include glycol compounds such as ethylene glycol (EG), diethylene glycol, triethylene glycol, propylene glycol, and polyethylene glycol (PEG); glycerin, etc. These may be used alone or in combination.

[0087] Among the above, at least one selected from the group consisting of water and lactone compounds is preferred as the second solvent because it has low viscosity and easily dissolves the solute (i.e., easily undergoes ionic dissociation). Water, in particular, is the most effective solvent for dissolving the solute. To prevent the second solvent from volatilizing, water may be combined with a polyhydric alcohol (e.g., EG, PEG).

[0088] The electrolytic solution may contain, for example, 5% by mass or more of water as a first solvent, 10% by mass or more, or 20% by mass or more of water. From the viewpoint of suppressing swelling of the electrolytic capacitor in a high-temperature environment, the water content in the electrolytic solution may be 70% by mass or less.

[0089] The electrolytic solution may contain, for example, 20% by mass or more of a lactone compound as a first solvent, 30% by mass or more, or 50% by mass or more of a lactone compound, and the second solvent may be 100% lactone compound.

[0090] (vi) Step (S6) of sealing the capacitor element The fabricated capacitor element is housed in, for example, a cylindrical case with a bottom. The case can be made of metals such as aluminum, stainless steel, copper, iron, or brass, or alloys of these. The capacitor element is then sealed by horizontally drawing the area near the open end of the case and crimping the open end to a sealing member to form a curl. Finally, a seat plate is placed on the curled portion, completing the electrolytic capacitor. An aging process may then be performed while applying a rated voltage.

[0091] FIG. 2 is a cross-sectional schematic diagram of an electrolytic capacitor according to the present disclosure, and FIG. 3 is a schematic view of a partially developed capacitor element of the electrolytic capacitor.

[0092] The electrolytic capacitor includes, for example, a capacitor element 10, a bottomed case 101 that houses capacitor element 10, a sealing member 102 that closes the opening of bottomed case 101, a seat plate 103 that covers sealing member 102, lead wires 104A and 104B that extend from sealing member 102 and pass through seat plate 103, and lead tabs 105A and 105B that connect the lead wires to electrodes of capacitor element 10. The vicinity of the open end of bottomed case 101 is drawn inward, and the open end is curled so as to be crimped to sealing member 102.

[0093] Capacitor element 10 is, for example, a wound body as shown in Fig. 3. The wound body includes anode foil 11 connected to lead tab 105A, cathode foil 12 connected to lead tab 105B, and separator 13. Separator 13 is formed with a first polymer layer and a second polymer layer, both of which are not shown.

[0094] The anode foil 11 and the cathode foil 12 are wound with a separator 13 interposed therebetween. The outermost periphery of the wound body is fixed with a stop tape 14. Note that Fig. 3 shows the wound body in a partially unfolded state before the outermost periphery is fixed.

[0095] The electrolytic capacitor may have at least one capacitor element, or may have a plurality of capacitor elements, the number of capacitor elements included in the electrolytic capacitor being determined depending on the intended use.

[0096] [Example] The present invention will be described in more detail below based on examples, but the present invention is not limited to these examples.

[0097] Example 1 An electrolytic capacitor with a rated voltage of 25V was fabricated as follows.

[0098] (a) Preparation of components An aluminum foil with a thickness of 100 μm was etched to roughen the surface, forming a 30 μm-thick porous portion on each side. The surface of the aluminum foil with the porous portion was then chemically treated to form a 40 nm-thick dielectric layer, thereby obtaining an anode foil.

[0099] A 50 μm thick aluminum foil was etched to roughen the surface, and a 10 nm thick dielectric layer was formed on the roughened aluminum foil surface by chemical conversion treatment.

[0100] A 50 μm thick nonwoven fabric was prepared as the raw material for the separator. The nonwoven fabric was made of cellulose and contained polyacrylamide as a paper strength enhancer. The density of the nonwoven fabric was 0.35 g / cm. 3 It was.

[0101] (b) Preparation of conductive polymer-containing solution 3,4-ethylenedioxythiophene and polystyrene sulfonic acid (PSS, weight average molecular weight 100,000) were dissolved in ion-exchanged water (first solvent) to prepare a mixed solution. Iron (III) sulfate (oxidant) was added while stirring the mixed solution to carry out a polymerization reaction. After that, the reaction The solution was dialyzed to remove unreacted monomers and oxidizing agent, and a conductive polymer-containing solution containing polyethylenedioxythiophene doped with approximately 5 mass % PSS (dopant) (PEDOT / PSS, conductive polymer component) was obtained.

[0102] The concentration of the conductive polymer component in the conductive polymer-containing liquid was 2% by mass. The viscosity of the conductive polymer-containing liquid measured at room temperature (20°C) using a vibration viscometer (VM-100A, manufactured by Sekonic Corporation) was 40 mPa s.

[0103] (c) Preparation of separator The conductive polymer-containing liquid was applied to both sides of the fiber structure using a gravure coater. After that, a drying process was performed to obtain a separator. The mass of the conductive polymer component per unit area of ​​the separator was 0.02 mg / cm. 2 The area coverage rate of one main surface of the separator with the conductive polymer component was 98%.

[0104] (d) Fabrication of capacitor elements The anode foil, cathode foil and separator were each cut to a predetermined size. Anode and cathode lead tabs were connected to the anode and cathode foils, respectively, and the anode and cathode foils were wound around the lead tabs, with a separator interposed between them. Anode and cathode lead wires were connected to the ends of each lead tab protruding from the wound assembly, respectively. The resulting wound assembly was again subjected to chemical conversion, forming a dielectric layer on the end surface of the anode foil. The ends of the outer surface of the wound assembly were secured with stop tape, yielding a capacitor element.

[0105] (e) Impregnation of electrolyte A mixed solvent containing water and ethylene glycol (EG) in a mass ratio of 15:85 was prepared as the second solvent. Orthophthalic acid (divalent) as the acid component and triethylamine as the base component were dissolved in the second solvent to prepare an electrolyte solution with a total solute concentration of 10 mass%. The equivalent ratio of orthophthalic acid to triethylamine was 1.0. The pH of the electrolyte solution was 6.2, and the electrical conductivity at 30°C was 3 mS / cm.

[0106] The capacitor element was immersed in the electrolytic solution in a reduced pressure atmosphere (40 kPa) for 5 minutes to impregnate the capacitor element with the electrolytic solution. When the capacitor element was impregnated with the electrolytic solution, the separator in the capacitor element was wet with water contained in the conductive polymer-containing solution.

[0107] (f) Encapsulation of capacitor elements The capacitor element impregnated with the electrolyte was sealed to complete the electrolytic capacitor (A1) as shown in Figure 2. After that, aging was carried out at 95°C for 90 minutes while applying the rated voltage.

[0108] <Evaluation> After aging, the ESR of electrolytic capacitor A1 was measured (measurement temperature: 20° C.) The evaluation results were shown as relative values ​​to the capacitance and ESR of electrolytic capacitor B1 produced in Comparative Example 1.

[0109] Comparative Examples 1 to 3, Examples 2 to 6 The electrical conductivity at 30°C was changed by varying the concentration of solute dissolved in the electrolyte. However, because the equivalent ratio of orthophthalic acid to triethylamine was maintained at 1.0, the pH of the electrolyte was in the range of 5.0 to 8.0.

[0110] 《Reference examples 1~9》 A capacitor element was assembled in the same manner as in Example 1, except that the conductive polymer-containing liquid was not applied to the fiber structure. The capacitor element was then immersed in a separately prepared conductive polymer-containing liquid (hereinafter referred to as the second conductive polymer-containing liquid) for 5 minutes in a reduced pressure atmosphere (40 kPa) to impregnate the capacitor element with the second conductive polymer-containing liquid. The capacitor element was then subjected to a drying treatment.

[0111] The dried capacitor elements were impregnated with an electrolytic solution and sealed in the same manner as in Comparative Examples 1 to 3 and Examples 1 to 6 to complete electrolytic capacitors (C1 to C9), which were evaluated in the same manner as above.

[0112] <Preparation of second conductive polymer-containing liquid> 3,4-ethylenedioxythiophene and polystyrene sulfonic acid (PSS, weight average molecular weight 100,000) were dissolved in ion-exchanged water to prepare a mixed solution. Iron (III) sulfate (oxidant) was added to the mixed solution while stirring, and a polymerization reaction was carried out. The reaction solution was then dialyzed. The unreacted monomer and the oxidizing agent were removed, and a second conductive polymer-containing liquid containing polyethylenedioxythiophene doped with approximately 5 mass % PSS (dopant) (PEDOT / PSS) was obtained.

[0113] The concentration of the conductive polymer component in the second conductive polymer-containing liquid was 1.5% by mass. The viscosity of the second conductive polymer-containing liquid measured at room temperature (20°C) using a vibration viscometer (VM-100A, manufactured by Sekonic Corporation) was 30 mPa s.

[0114] [Table 1]

[0115] The results of Table 1 are shown in Figure 4. Graph A shows the relationship between ESR and the electrical conductivity of the electrolyte for electrolytic capacitors B1 to B3 and A1 to A6. Graph B shows the relationship between ESR and the electrical conductivity of the electrolyte for electrolytic capacitors C1 to C9. It can be seen that when the separator is impregnated with a conductive polymer-containing solution rather than the capacitor element, the electrical conductivity of the electrolyte becomes extremely important. Specifically, when the electrical conductivity of the electrolyte is less than 3 mS / cm, the ESR increases sharply, whereas when the electrical conductivity is 3 mS / cm or higher, the ESR decreases significantly and converges to a sufficiently small ESR. On the other hand, for electrolytic capacitors C1 to C9, the ESR does not depend on the electrical conductivity of the electrolyte.

[0116] Comparative Examples 4 to 6 and Examples 7 to 12 Next, a second solvent containing 100% γ-butyrolactone was used to control the total concentration of solutes in the electrolyte solution, and electrolyte solutions with electrical conductivities at 30°C shown in Table 1 were prepared. The equivalent ratio of orthophthalic acid to triethylamine was 1.0. Except for using the above electrolyte solutions, electrolytic capacitors (B4 to B6 and A7 to A12) were completed in the same manner as in Comparative Examples 1 to 3 and Examples 1 to 6, and evaluated in the same manner as above. The results are shown in Table 2.

[0117] [Table 2]

[0118] From Table 2, it can be seen that the electrical conductivity and ESR of the electrolyte show a similar correspondence relationship regardless of the type of solvent in the electrolyte.

[0119] The electrolytic capacitors of Examples 1 to 6 were disassembled, and the areas of the anode lead and cathode lead that protruded from the separator were examined. Almost no adhesion of the conductive polymer component was observed. Furthermore, the capacitor elements were disassembled, and the end faces of the anode foil and cathode foil were examined. Almost no adhesion of the conductive polymer component was observed. On the other hand, the electrolytic capacitors of Reference Examples 4 to 9 were disassembled, and the areas of the anode lead and cathode lead that protruded from the separator were examined. Furthermore, the capacitor elements were disassembled, and the end faces of the anode foil and cathode foil were examined. Almost the entire end faces were coated with the conductive polymer component. [Industrial Applicability]

[0120] The present invention is highly superior to, for example, conventional aluminum electrolytic capacitors, and is useful in applications where conventional aluminum electrolytic capacitors have been used. [Explanation of symbols]

[0121] 100: Electrolytic capacitor 101: Bottomed case 102: Sealing member 103: Seat board 104A, 104B: Lead wires 105A, 105B: Lead tab 10: Capacitor element 11: Anode foil 12: Cathode foil 13: Separator 14: Winding tape

Claims

1. providing an anode foil, a cathode foil, and a fiber structure having a porous portion with a dielectric layer; preparing a conductive polymer-containing liquid containing a conductive polymer component and a first solvent; a step of applying the conductive polymer-containing liquid to the fiber structure and then removing at least a portion of the first solvent to prepare a separator; fabricating a capacitor element using the anode foil, the separator, and the cathode foil; and impregnating the capacitor element with an electrolyte solution. The method for producing an electrolytic capacitor, wherein the electrolytic solution has an electrical conductivity of 3.0 mS / cm or more at 30°C.

2. The method for producing an electrolytic capacitor according to claim 1 , wherein the electrolytic solution contains 10% by mass or more of a solute.

3. the electrolyte solution includes a second solvent; 3. The method for producing an electrolytic capacitor according to claim 1, wherein the second solvent contains at least one selected from the group consisting of water and lactone compounds.

4. The method for manufacturing an electrolytic capacitor according to claim 3 , wherein the electrolytic solution contains 5 mass % or more of the water as the first solvent.

5. The method for manufacturing an electrolytic capacitor according to claim 3 , wherein the electrolytic solution contains 20% by mass or more of the lactone compound as the first solvent.

6. The method for manufacturing an electrolytic capacitor according to any one of claims 1 to 5, wherein the pH of the electrolytic solution is 5 or more.

7. 7. The method for manufacturing an electrolytic capacitor according to claim 1, wherein in the step of impregnating the capacitor element with the electrolytic solution, the capacitor element is impregnated with the electrolytic solution in a state in which the separator contains the first solvent.

8. The method for manufacturing an electrolytic capacitor according to any one of claims 1 to 7, wherein the cathode foil has a chemical conversion coating.

9. 10. An electrolytic capacitor manufactured by the method of claim 1.

10. the capacitor element includes an anode lead connected to the anode foil and a cathode lead connected to the cathode foil; 10. The electrolytic capacitor according to claim 9, wherein the areas of the anode lead and the cathode lead that protrude from the separator are substantially not covered with the conductive polymer component.

11. 11. The electrolytic capacitor according to claim 9, wherein in the capacitor element, an end face of the anode foil and an end face of the cathode foil are substantially not covered with the conductive polymer component.

12. 12. The electrolytic capacitor according to claim 9, wherein a mass Mp of the conductive polymer component supported by the anode foil and a mass Ms of the conductive polymer component supported by the separator satisfy Ms > Mp.

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