Method for manufacturing electrolytic capacitor, electrolytic capacitor, first processing solution, and second processing solution

Abstract

This method for manufacturing an electrolytic capacitor comprises: a step for preparing a first processing solution containing a first conductive polymer component; a step for preparing a second processing solution containing a second conductive polymer component; a step for coating a separator with the first processing solution such that the first conductive polymer component is adhered thereto; a step for coating at least one of an anode foil and a cathode foil comprising a dielectric layer with the second processing solution such that the second conductive polymer component is adhered thereto; a step for producing a capacitor element by sequentially laminating the anode foil, the separator, and the cathode foil; and a step for immersing the capacitor element in a liquid component. The first processing solution either contains less than 10 mass% of a first polyhydric alcohol or does not substantially contain thereof. The second processing solution contains 10 mass% or more of a second polyhydric alcohol.

Description

Method for manufacturing electrolytic capacitor, electrolytic capacitor, first treatment liquid, and second treatment liquid

[0001] The present disclosure relates to a method for manufacturing an electrolytic capacitor, an electrolytic capacitor, a first treatment liquid, and a second treatment liquid.

[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] Patent Document 1 discloses "a method for manufacturing an electrolytic capacitor, comprising the steps of: preparing an electrode foil; preparing a first conductive polymer dispersion containing a first conductive polymer component and a first dispersion medium; applying the first conductive polymer dispersion to a surface of the electrode foil by a coating method, and then removing at least a portion of the first dispersion medium to form a first conductive polymer layer containing the first conductive polymer component; and fabricating a capacitor element using the electrode foil on which the first conductive polymer layer has been formed."

[0004] Patent Document 2 describes a capacitor element manufacturing method comprising the steps of: preparing an anode foil, a cathode foil, and a fiber structure each having a dielectric layer; preparing a conductive polymer dispersion liquid containing a conductive polymer component and a dispersion medium; applying the conductive polymer dispersion liquid to the fiber structure and then removing at least a portion of the dispersion medium to prepare a separator; and sequentially laminating the anode foil, the separator, and the cathode foil to prepare a capacitor element, wherein the dispersion medium contains water, the fiber structure contains 50% by mass or more of synthetic fibers, and the density of the fiber structure is 0.2 g / cm. ３ Above, 0.45g / cm ３ "A method for manufacturing an electrolytic capacitor, wherein the manufacturing cost is less than 100%."

[0005] International Publication No. WO 2020 / 158780 International Publication No. WO 2020 / 158783

[0006] One aspect of the present disclosure relates to a method for manufacturing an electrolytic capacitor. The method includes the steps of: preparing an anode foil, a cathode foil, and a separator each having a dielectric layer; preparing a first treatment liquid containing a first conductive polymer component; preparing a second treatment liquid containing a second conductive polymer component; applying the first treatment liquid to the separator to adhere the first conductive polymer component; applying the second treatment liquid to at least one of the anode foil and the cathode foil to adhere the second conductive polymer component; and, after the second conductive polymer component adhering step, sequentially stacking the anode foil, the separator with the first conductive polymer component adhered thereto, and the cathode foil to form a capacitor element; and impregnating the capacitor element with a liquid component. The first treatment liquid may contain or is substantially free of a first polyhydric alcohol, and the first treatment liquid contains 0% by mass or more and less than 10% by mass of the first polyhydric alcohol. The second treatment liquid contains a second polyhydric alcohol, and the content of the second polyhydric alcohol in the second treatment liquid is 10% by mass or more.

[0007] Another aspect of the present disclosure relates to an electrolytic capacitor. The electrolytic capacitor includes a capacitor element and a liquid component. The capacitor element includes an anode foil including a dielectric layer, a cathode foil, a separator interposed between the anode foil and the cathode foil, a first conductive polymer component adhered to the separator, and a second conductive polymer component adhered to at least one of the anode foil and the cathode foil. The first conductive polymer component has higher solubility in water than the second conductive polymer component.

[0008] Another aspect of the present disclosure relates to a first treatment liquid applied to a separator constituting a capacitor element of an electrolytic capacitor including a capacitor element and a liquid component. The first treatment liquid includes a first conductive polymer component and either contains or is substantially free of a first polyhydric alcohol, and the content of the first polyhydric alcohol in the first treatment liquid is 0% by mass or more and less than 10% by mass. The first conductive polymer component adhered to the separator by application of the first treatment liquid to the separator migrates to another adjacent conductive polymer component during impregnation of the capacitor element with the liquid component.

[0009] Yet another aspect of the present disclosure relates to a second treatment liquid used together with the first treatment liquid and applied to at least one of an anode foil and a cathode foil constituting a capacitor element of an electrolytic capacitor including a capacitor element and a liquid component, the second treatment liquid including a second conductive polymer component and a second polyhydric alcohol, and a content of the second polyhydric alcohol in the second treatment liquid being 10 mass% or more.

[0010] According to the present disclosure, the ESR of an electrolytic capacitor can be reduced.

[0011] 1 is a cross-sectional view schematically illustrating an electrolytic capacitor according to an embodiment of the present disclosure;

[0012] Before describing the embodiments of the present disclosure, we will briefly explain the problems in the prior art. A capacitor element is fabricated by applying a dispersion of a conductive polymer component to the surfaces of an anode foil, a cathode foil, and a separator, respectively, to adhere the conductive polymer component, and then placing the separator between the anode foil and the cathode foil. However, the interfacial resistance between the anode foil and the separator and the cathode foil is high, which can increase the ESR.

[0013] The following describes embodiments of the present disclosure using examples, but the present disclosure is not limited to the examples described below. In the following description, specific numerical values ​​and materials may be exemplified, but other numerical values ​​and materials may be applied as long as the effects of the present disclosure are obtained. In this specification, the term "numerical value A to numerical value B" includes numerical value A and numerical value B and can be read as "numerical value A or more and numerical value B or less." In the following description, when lower and upper limits are exemplified for numerical values ​​of specific physical properties or conditions, any of the exemplified lower limits and any of the exemplified upper limits can be arbitrarily combined, as long as the lower limit is not equal to or greater than the upper limit. When multiple materials are exemplified, one of the materials may be selected and used alone, or two or more materials may be used in combination.

[0014] The present disclosure also encompasses combinations of two or more features arbitrarily selected from the appended claims, i.e., two or more features arbitrarily selected from the appended claims can be combined unless a technical contradiction arises.

[0015] [Method for Manufacturing Electrolytic Capacitor] A method for manufacturing an electrolytic capacitor according to an embodiment of the present disclosure includes first to seventh steps.

[0016] First step: Prepare an anode foil, a cathode foil, and a separator each having a dielectric layer.

[0017] Step 2: Preparing a first treatment liquid containing a first conductive polymer component. The first treatment liquid contains or is substantially free of a first polyhydric alcohol, and the content of the first polyhydric alcohol in the first treatment liquid is 0% by mass or more and less than 10% by mass.

[0018] Step 3: Preparing a second treatment liquid containing a second conductive polymer component. The second treatment liquid contains a second polyhydric alcohol, and the content of the second polyhydric alcohol in the second treatment liquid is 10% by mass or more.

[0019] Fourth step: The first treatment liquid is applied to the separator to adhere the first conductive polymer component. By the fourth step, a first conductive polymer layer containing the first conductive polymer component is formed on at least the surface of the separator.

[0020] Fifth step: A second treatment liquid is applied to at least one of the anode foil and the cathode foil to adhere the second conductive polymer component, and a second conductive polymer layer containing the second conductive polymer component is formed on at least one of the surfaces of the anode foil and the cathode foil by the fifth step.

[0021] Sixth step: The anode foil, the separator to which the first conductive polymer component is attached, and the cathode foil are laminated in this order to prepare a capacitor element.

[0022] Seventh step: The capacitor element is impregnated with the liquid component.

[0023] Hereinafter, the second treatment liquid applied to the anode foil will also be referred to as the "second-A treatment liquid." The second treatment liquid applied to the cathode foil will also be referred to as the "second-B treatment liquid." The second-A treatment liquid contains a second-A conductive polymer component as the second conductive polymer component and a second-A polyhydric alcohol as the second polyhydric alcohol. The second-B treatment liquid contains a second-B conductive polymer component as the second conductive polymer component and a second-B polyhydric alcohol as the second polyhydric alcohol. The second-A treatment liquid and the second-B treatment liquid may have the same liquid composition or different liquid compositions. The second treatment liquid may be applied only to the anode foil, only to the cathode foil, or to both the anode foil and the cathode foil. The anode foil, the cathode foil, and the separator will also be collectively referred to as the "components." The anode foil and the cathode foil will also be collectively referred to as the "electrode foil."

[0024] The polyhydric alcohol contributes to improving the crystallinity (orientation) of the conductive polymer component and thereby improving the conductivity, and also contributes to improving the adhesion (impregnation) of the conductive polymer component to the component members.

[0025] By adding a large amount (10% by mass or more) of the second polyhydric alcohol to the second treatment liquid, the crystallinity of the second conductive polymer component is improved, and the conductivity of the second conductive polymer component is improved. Furthermore, the second conductive polymer component has high adhesiveness to the electrode foil surface, and the second conductive polymer component remains firmly attached to the electrode foil surface even after impregnation with the liquid component. Electrode foil to which the second conductive polymer component is attached using the second treatment liquid is advantageous in terms of reducing ESR and increasing capacity, particularly in the low-frequency range.

[0026] The first treatment liquid contains a small amount (less than 10% by mass) of the first polyhydric alcohol, or the first treatment liquid is substantially free of the first polyhydric alcohol. Therefore, the first conductive polymer component has relatively low adhesion to the separator surface. Therefore, in the seventh step (impregnation step of the capacitor element with the liquid component), the liquid component is impregnated between the electrode foil and the separator, and the first conductive polymer component (particularly the first conductive polymer component adhered to the outer surface of the separator) migrates to the second conductive polymer component. This forms numerous conductive paths between the first conductive polymer component adhered to the separator surface and the second conductive polymer component adhered to the electrode foil surface, reducing the interfacial resistance between the electrode foil and the separator.

[0027] From the above, it is possible to obtain an electrolytic capacitor with a low ESR by using the first treatment liquid for coating the separator and the second treatment liquid for coating the electrode foil.

[0028] (First Step) An anode foil, a cathode foil, and a separator each having a dielectric layer are prepared. These components will be described below.

[0029] (Anode foil with dielectric layer) Examples of the anode foil include metal foils containing at least one valve metal such as titanium, tantalum, aluminum, and niobium, and may be a metal foil of a valve metal (e.g., aluminum foil). 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. The thickness of the anode foil may be 15 μm or more and 300 μm or less. The surface of the anode foil may be roughened by etching or the like. The anode foil with a roughened surface has a core portion and a porous portion continuous with the core portion.

[0030] A dielectric layer is formed on the surface of the anode foil. The dielectric layer is formed, for example, by chemically treating the anode foil. In this case, the dielectric layer may contain an oxide of a valve metal (e.g., aluminum oxide). When chemically treating an anode foil having a porous portion on its surface, the dielectric layer is formed so as to cover the metal skeleton that constitutes the porous portion. Note that the dielectric layer may be formed of any dielectric other than an oxide of a valve metal as long as it functions as a dielectric.

[0031] In an electrolytic capacitor, the end surface of the anode foil does not necessarily have to be provided with a conductive polymer layer, but it is preferable that the end surface of the anode foil has a dielectric layer formed thereon.

[0032] (Cathode foil) The cathode foil is not particularly limited as long as it functions as a cathode. Examples of the cathode foil include metal foil (e.g., aluminum foil). The type of metal is not particularly limited, and may be a valve metal or an alloy containing a valve metal. The thickness of the cathode foil may be 15 μm or more and 300 μm or less. The surface of the cathode foil may be roughened or chemically treated as necessary.

[0033] The cathode foil may include a conductive coating layer. When the metal foil includes a valve metal, the coating layer may include carbon and at least one metal having a lower ionization tendency than the valve metal. This facilitates improving the acid resistance of the metal foil. When the metal foil includes aluminum, the coating layer may include at least one selected from the group consisting of carbon, nickel, titanium, tantalum, and zirconium. In particular, the coating layer may include nickel and / or titanium, which are low in cost and resistance.

[0034] The thickness of the coating layer may be 5 nm or more, 10 nm or more, or 200 nm or less. The coating layer may be formed by vapor deposition or sputtering of the metal on the metal foil. Alternatively, the coating layer may be formed by vapor deposition of a conductive carbon material on the metal foil or by applying a carbon paste containing a conductive carbon material. Examples of conductive carbon materials include graphite, hard carbon, soft carbon, and carbon black.

[0035] (Separator) A porous sheet can be used as the separator. Examples of porous sheets include woven fabric, nonwoven fabric, and microporous membrane. The thickness of the separator is not particularly limited and may be in the range of 10 to 300 μm. Examples of separator materials include cellulose, polyethylene terephthalate, polybutylene terephthalate, polyphenylene sulfide, vinylon, nylon, aromatic polyamide, polyimide, polyamideimide, polyetherimide, rayon, glass, etc.

[0036] (Second Step) (First Treatment Liquid) In the second step, a first treatment liquid containing a first conductive polymer component is prepared. The first treatment liquid is applied to a capacitor element and a separator constituting the capacitor element of an electrolytic capacitor containing a liquid component.

[0037] The first treatment liquid contains a first polyhydric alcohol or is substantially free of the first polyhydric alcohol. The term "substantially free of the first polyhydric alcohol" means that the content of the first polyhydric alcohol is below the detection limit of an analytical device (such as a liquid chromatography analytical device). From the viewpoint of reducing ESR, the content of the first polyhydric alcohol in the first treatment liquid is 0% by mass or more and less than 10% by mass, and preferably 0% by mass or more and 5% by mass or less.

[0038] The first conductive polymer component is dispersed (or dissolved) in the first treatment liquid. The first treatment liquid may contain water as a dispersion medium (or solvent), or may contain water and a first polyhydric alcohol. The first polyhydric alcohol may be a compound used as an organic solvent, or may be a mixed dispersion medium (mixed solvent) of water and the first polyhydric alcohol. Water in which the first polyhydric alcohol is dissolved may be used as the dispersion medium (or solvent). The dispersion medium (or solvent) may contain components other than water and the first polyhydric alcohol. The other components may include a non-aqueous solvent exemplified as a liquid component.

[0039] In the first treatment liquid, the mass of the first polyhydric alcohol is preferably less than 5 times the mass of the first conductive polymer component, and more preferably 2.5 times or less the mass of the first conductive polymer component.

[0040] (Third Step) (Second Treatment Liquid) In the third step, a second treatment liquid containing a second conductive polymer component is prepared. The second treatment liquid is used together with the first treatment liquid and is applied to the electrode foil that constitutes the capacitor element of an electrolytic capacitor containing a capacitor element and a liquid component. That is, the second-A treatment liquid is applied to the anode foil, and the second-B treatment liquid is applied to the cathode foil.

[0041] The second treatment liquid contains a second conductive polymer and a second polyhydric alcohol. From the viewpoint of reducing ESR, the content of the second polyhydric alcohol in the second treatment liquid is 10% by mass or more, and preferably 10% by mass or more (or 15% by mass or more) and 30% by mass or less.

[0042] The second conductive polymer component is dispersed (or dissolved) in the second treatment liquid. The second treatment liquid may contain water and a second polyhydric alcohol as a dispersion medium (or solvent). The second polyhydric alcohol may be a compound used as an organic solvent, or may be a mixed dispersion medium (mixed solvent) of water and the second polyhydric alcohol. Water in which the second polyhydric alcohol is dissolved may be used as the dispersion medium (or solvent). The dispersion medium (or solvent) may contain components other than water and the second polyhydric alcohol. The other components may include a non-aqueous solvent exemplified as a liquid component.

[0043] In the second treatment liquid, the mass of the second polyhydric alcohol is preferably 5 to 30 times the mass of the second conductive polymer component, more preferably 5 to 25 times the mass of the second conductive polymer component, and even more preferably 7 to 15 times the mass of the second conductive polymer component.

[0044] The polyhydric alcohol and conductive polymer component used in the treatment liquids (first treatment liquid and second treatment liquid) will be described below.

[0045] (Polyhydric Alcohol) The polyhydric alcohol preferably contains at least one selected from the group consisting of glycol compounds, glycerin compounds, and sugar alcohol compounds. In this case, the conductive polymer component is likely to swell. The second polyhydric alcohol may be the same compound as the first polyhydric alcohol, or a compound different from the first polyhydric alcohol.

[0046] Examples of glycol compounds include ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, polyalkylene glycols (e.g., polyethylene glycol), polyoxyethylene polyoxypropylene glycol (ethylene oxide-propylene oxide copolymer), etc. Examples of glycerin compounds include glycerin and polyglycerin, etc. Examples of sugar alcohol compounds include mannitol, xylitol, sorbitol, erythritol, and pentaerythritol, etc. Among these, ethylene glycol is preferred from the viewpoints of affinity with the treatment liquid and film-forming properties of the conductive polymer component.

[0047] The boiling point of the polyhydric alcohol may be higher than 100° C., or may be 110° C. or higher, 150° C. or higher, or 200° C. or higher, or may be 400° C. or lower, 300° C. or lower, 250° C. or lower, or 200° C. or lower. The boiling point may be in the range of 110° C. to 400° C. (e.g., in the range of 150° C. to 350° C.).

[0048] (Conductive Polymer Component) The conductive polymer component may contain a conductive polymer and may be composed of only a conductive polymer. Alternatively, the conductive polymer component may contain a conductive polymer and a dopant. The second conductive polymer component may be the same compound as the first conductive polymer component, or may be a compound different from the first conductive polymer component.

[0049] Examples of conductive polymers include polypyrrole, polythiophene, polyfuran, polyaniline, polyacetylene, and derivatives thereof. These derivatives include polymers with polypyrrole, polythiophene, polyfuran, polyaniline, and polyacetylene as their basic skeletons. For example, polythiophene derivatives include poly(3,4-ethylenedioxythiophene). These conductive polymers may be used alone or in combination. Furthermore, the conductive polymer may be a copolymer of two or more monomers. The weight-average molecular weight of the conductive polymer is not particularly limited and may be in the range of 1,000 to 100,000, for example. One preferred example of a conductive polymer is poly(3,4-ethylenedioxythiophene) (PEDOT).

[0050] The conductive polymer may be doped with a dopant. From the viewpoint of suppressing dedoping from the conductive polymer, it is preferable to use a polymer dopant as the dopant. Examples of polymer dopants include polyvinyl sulfonic acid, polystyrene sulfonic acid, polyallylsulfonic acid, polyacrylic sulfonic acid, polymethacrylic sulfonic acid, poly(2-acrylamido-2-methylpropanesulfonic acid), polyisoprene sulfonic acid, polyacrylic acid, and the like. These may be used alone or in combination of two or more. At least a portion of these may be added in the form of a salt. A preferred example of the dopant is polystyrene sulfonic acid (PSS).

[0051] The dopant may be a dopant containing an acidic group, or may be a polymeric dopant containing an acidic group. Examples of the acidic group include a sulfonic acid group, a carboxyl group, etc. The polymeric dopant containing an acidic group is a polymer in which at least some of the constituent units contain an acidic group. Examples of such polymeric dopants include the polymeric dopants described above.

[0052] The weight-average molecular weight of the dopant is not particularly limited, but may be in the range of 1,000 to 100,000 in order to facilitate the formation of a homogeneous conductive polymer layer.

[0053] The dopant may be polystyrene sulfonic acid, and the conductive polymer may be poly(3,4-ethylenedioxythiophene). That is, the conductive polymer component may be poly(3,4-ethylenedioxythiophene) doped with polystyrene sulfonic acid.

[0054] When a conductive polymer doped with a dopant is used, the pH of the treatment solution is preferably less than 7.0, and may be 6.0 or less or 5.0 or less, in order to suppress dedoping of the dopant. The pH of the treatment solution may be 1.0 or more, or 2.0 or more.

[0055] The conductive polymer component may be present in the treatment liquid in the form of particles. In the volume-based particle size distribution of the particles of the conductive polymer component, the mode of particle size may be 10 nm or more, or 20 nm or more, or may be 1000 nm or less, 500 nm or less, 200 nm or less, or 100 nm or less. The volume-based particle size distribution can be determined using a laser diffraction / scattering particle size distribution analyzer.

[0056] The mode of particle size of the conductive polymer component particles may be in the range of 20 nm to 200 nm (e.g., in the range of 20 nm to 100 nm). Furthermore, in the volume-based particle size distribution, the volume-based proportion of particles with particle sizes in the range of 20 nm to 100 nm may be 90% or more of the total. These ranges facilitate the formation of a conductive polymer layer containing the conductive polymer component in the pores of the members (electrode foil and separator).

[0057] The content of the conductive polymer component in the treatment solution may be 0.5% by mass or more, or 1.0% by mass or more, and may be 4.0% by mass or less, 3.0% by mass or less, or 2.0% by mass or less. The content may be in the range of 0.5 to 4.0% by mass, or 1.0 to 4.0% by mass. Within any of these ranges, the upper limit may be 3.0% by mass or 2.0% by mass. From the viewpoints of excellent physical properties and stability over time of the treatment solution, and a good balance between the ESR of the electrolytic capacitor and cost, the content is preferably in the range of 1.0 to 3.0%. Note that, when the treatment solution contains a dopant, the mass of the dopant is included in the mass of the conductive polymer component.

[0058] (Steps 4 and 5) A treatment liquid is applied to each component, and the conductive polymer component is adhered to the surface of the component. This forms a conductive polymer layer containing the conductive polymer component on the surface of the component. After application, the coating may be dried to remove at least a portion of the dispersion medium (solvent). The drying may be performed by heating or under reduced pressure.

[0059] In the fourth step, a first treatment liquid is applied to the separator, and a first conductive polymer component is adhered thereto. This forms a first conductive polymer layer containing the first conductive polymer component on the separator surface. In the fifth step, a second treatment liquid is applied to the electrode foil, and a second conductive polymer component is adhered thereto. That is, a second-A treatment liquid is applied to the anode foil (dielectric layer), and a second-A conductive polymer component is adhered thereto. This forms a second-A conductive polymer layer containing the second-A conductive polymer component on the anode foil surface (on the dielectric layer). A second-B treatment liquid is applied to the cathode foil, and a second-B conductive polymer component is adhered thereto. This forms a second-B conductive polymer layer containing the second-B conductive polymer component on the cathode foil surface.

[0060] The method for applying the treatment liquid is not limited, and application may be performed by a known method. For example, a method using a coater may be used, the treatment liquid may be sprayed, or the object to be applied may be immersed in the treatment liquid. Examples of methods using a coater include gravure coating and die coating. Note that methods for applying the first treatment liquid to the separator include a method in which the separator is impregnated with the first treatment liquid. The first treatment liquid applied to the separator permeates into the separator, and a first conductive polymer layer may be formed over the entire thickness of the separator.

[0061] The fourth and / or fifth steps may include a step (a) of removing a part of the dispersion medium (or solvent) after application of the treatment liquid so that the polyhydric alcohol remains in the conductive polymer layer. In this case, excessive shrinkage of the formed conductive polymer layer can be suppressed, and the impregnation of the liquid component can be improved.

[0062] The method for removing the dispersion medium (or solvent) from the treatment liquid is not particularly limited, as long as it is possible to remove a portion of the dispersion medium (or solvent) so that the polyhydric alcohol remains in the conductive polymer layer. The dispersion medium (or solvent) may be removed by heating and / or reducing pressure, and it is preferable to at least heat the dispersion medium (or solvent).

[0063] When heating is performed, it is preferable to remove a portion of the dispersion medium (or solvent) by heating at a temperature of 100°C or higher. Heating at a temperature of 100°C or higher allows for rapid removal of water from the treatment solution. The heating temperature is preferably a temperature at which the polyhydric alcohol does not boil or decompose. When the polyhydric alcohol is a compound without a clear boiling point, it is preferable to heat at a temperature at which evaporation of the polyhydric alcohol is minimal and the polyhydric alcohol does not decompose. The heating temperature may be 100°C or higher, 120°C or higher, or 140°C or higher, or 200°C or lower, or 160°C or lower. The heating temperature may be in the range of 100°C to 200°C. There are no particular limitations on the heating time, as long as it is a time that allows for adequate removal of a portion of the dispersion medium (or solvent). An example heating time is in the range of 5 to 60 minutes.

[0064] When forming the second-A conductive polymer layer on the dielectric layers formed on both sides of the anode foil, the treatment solution may be applied to one surface and then heated, and the treatment solution may be applied to the other surface and then heated. A similar method can be applied when forming the second-B conductive polymer layer on both sides of the cathode foil.

[0065] For example, step (a) may be performed so that the mass of the polyhydric alcohol in the conductive polymer layer is greater than the mass of water in the conductive polymer layer. In this case, the conductive polymer component is likely to swell in a treatment liquid with a high water content, and the swollen state is likely to be maintained to some extent while the conductive polymer layer is formed. In step (7), the liquid component is likely to be impregnated into the second conductive polymer layer.

[0066] (Step 6) An anode foil having a second conductive polymer component attached thereto, a separator having a first conductive polymer component attached thereto, and a cathode foil having a second conductive polymer component attached thereto are sequentially laminated to produce a capacitor element. The capacitor element includes a solid electrolyte containing the first conductive polymer component and the second conductive polymer component. Hereinafter, the separator having the first conductive polymer component attached thereto will also be referred to as "separator S." The anode foil having the second conductive polymer component attached thereto will also be referred to as "anode foil P." The cathode foil having the second conductive polymer component attached thereto will also be referred to as "cathode foil N."

[0067] In the sixth step, a wound body may be obtained by winding the anode foil P and the cathode foil N with a separator S interposed between the anode foil P and the cathode foil N. In the sixth step, a laminate may be obtained by stacking the anode foil P and the cathode foil N with a separator S interposed between the anode foil P and the cathode foil N.

[0068] (Seventh Step) The capacitor element is impregnated with a liquid component. The liquid component impregnation step (seventh step) includes a step of causing the first conductive polymer component to migrate into the second conductive polymer component, thereby increasing the conductive paths between the second conductive polymer component and the first conductive polymer component.

[0069] The liquid component protects the conductive polymer component and suppresses oxidative degradation of the conductive polymer component. The decrease in conductivity due to oxidative degradation of the conductive polymer component is suppressed, and an increase in ESR due to the decrease in conductivity is suppressed. Furthermore, the liquid component repairs defects in the dielectric layer, suppressing an increase in leakage current due to defects in the dielectric layer.

[0070] (Liquid Component) The liquid component impregnated in the capacitor element may be a non-aqueous solvent or an electrolytic solution. The electrolytic solution contains a non-aqueous solvent and a solute (e.g., a salt described below) dissolved in the non-aqueous solvent. In this specification, the liquid component may be a component that is liquid at room temperature (25°C) or a component that is liquid at the temperature at which the electrolytic capacitor is used.

[0071] The non-aqueous solvent used in the liquid component may be an organic solvent, an ionic liquid, or a protic solvent. Examples of the non-aqueous solvent include polyhydric alcohols such as ethylene glycol and propylene glycol, cyclic sulfones such as sulfolane, lactones such as γ-butyrolactone, amides such as N-methylacetamide, N,N-dimethylformamide, and N-methyl-2-pyrrolidone, esters such as methyl acetate, carbonate compounds such as propylene carbonate, ethers such as 1,4-dioxane, ketones such as methyl ethyl ketone, and formaldehyde.

[0072] Furthermore, a polymer solvent may be used as the non-aqueous solvent. Examples of polymer solvents include polyalkylene glycol, polyalkylene glycol derivatives, and compounds in which at least one hydroxyl group in a polyhydric alcohol has been substituted with polyalkylene glycol (including derivatives). Specific examples of polymer solvents include polyethylene glycol (PEG), polyethylene glycol glyceryl ether, polyethylene glycol diglyceryl ether, polyethylene glycol sorbitol ether, polypropylene glycol, polypropylene glycol glyceryl ether, polypropylene glycol diglyceryl ether, polypropylene glycol sorbitol ether, and polybutylene glycol. Further examples of polymer solvents include ethylene glycol-propylene glycol copolymers, ethylene glycol-butylene glycol copolymers, and propylene glycol-butylene glycol copolymers. One type of non-aqueous solvent may be used alone, or two or more types may be used in combination.

[0073] In order to prevent the dopant from being dedoped, the liquid component may contain an acid component, such as a polycarboxylic acid or a monocarboxylic acid.

[0074] Examples of the polycarboxylic acid include aliphatic polycarboxylic acids ([saturated polycarboxylic acids, for example, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, 1,6-decanedicarboxylic acid, 5,6-decanedicarboxylic acid]; [unsaturated polycarboxylic acids, for example, maleic acid, fumaric acid, itanoic acid]), aromatic polycarboxylic acids (for example, phthalic acid, isophthalic acid, terephthalic acid, trimellitic acid, pyromellitic acid), and alicyclic polycarboxylic acids (for example, cyclohexane-1,2-dicarboxylic acid, cyclohexene-1,2-dicarboxylic acid, etc.).

[0075] Examples of the monocarboxylic acid include aliphatic monocarboxylic acids (having 1 to 30 carbon atoms) ([saturated monocarboxylic acids such as formic acid, acetic acid, propionic acid, butyric acid, isobutyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, lauric acid, myristic acid, stearic acid, and behenic acid]; [unsaturated monocarboxylic acids such as acrylic acid, methacrylic acid, and oleic acid]), aromatic monocarboxylic acids (such as benzoic acid, cinnamic acid, and naphthoic acid), and oxycarboxylic acids (such as salicylic acid, mandelic acid, and resorcylic acid).

[0076] Among these, maleic acid, phthalic acid, benzoic acid, pyromellitic acid, and resorcylic acid are thermally stable and are therefore preferably used.

[0077] An inorganic acid may be used as the acid component. Typical examples of inorganic acids include phosphoric acid, phosphorous acid, hypophosphorous acid, alkyl phosphate esters, boric acid, fluoroboric acid, tetrafluoroboric acid, hexafluorophosphoric acid, benzenesulfonic acid, and naphthalenesulfonic acid. Alternatively, a composite compound of an organic acid and an inorganic acid may be used as the acid component. Examples of such composite compounds include borodiglycolic acid, borodisalic acid, and borodisalicylic acid.

[0078] The liquid component may contain a base component in addition to the acid component. The base component may be a compound having an alkyl-substituted amidine group, such as an imidazole compound, a benzimidazole compound, or an alicyclic amidine compound (a pyrimidine compound, an imidazoline compound). Specifically, 1,8-diazabicyclo[5,4,0]undecene-7, 1,5-diazabicyclo[4,3,0]nonene-5, 1,2-dimethylimidazolinium, 1,2,4-trimethylimidazoline, 1-methyl-2-ethyl-imidazoline, 1,4-dimethyl-2-ethylimidazoline, 1-methyl-2-heptylimidazoline, 1-methyl-2-(3'heptyl)imidazoline, 1-methyl-2-dodecylimidazoline, 1,2-dimethyl-1,4,5,6-tetrahydropyrimidine, 1-methylimidazole, and 1-methylbenzimidazole are preferred. By using these, a capacitor with excellent impedance performance can be obtained.

[0079] The base component may be a quaternary salt of a compound having an alkyl-substituted amidine group. Examples of such base components include imidazole compounds, benzimidazole compounds, and alicyclic amidine compounds (pyrimidine compounds, imidazoline compounds) quaternized with an alkyl group or arylalkyl group having 1 to 11 carbon atoms. Specifically, 1-methyl-1,8-diazabicyclo[5,4,0]undecene-7, 1-methyl-1,5-diazabicyclo[4,3,0]nonene-5, 1,2,3-trimethylimidazolinium, 1,2,3,4-tetramethylimidazolinium, 1,2-dimethyl-3-ethyl-imidazolinium, 1,3,4-trimethyl-2-ethylimidazolinium, 1,3-dimethyl-2-heptylimidazolinium, 1,3-dimethyl-2-(3'heptyl)imidazolinium, 1,3-dimethyl-2-dodecylimidazolinium, 1,2,3-trimethyl-1,4,5,6-tetrahydropyrimidium, 1,3-dimethylimidazolium, 1-methyl-3-ethylimidazolium, 1,3-dimethylbenzimidazolium is preferred. By using these, a capacitor with excellent impedance performance can be obtained.

[0080] Tertiary amines may also be used as the base component. Examples of tertiary amines include trialkylamines (trimethylamine, dimethylethylamine, methyldiethylamine, triethylamine, dimethyl-n-propylamine, dimethylisopropylamine, methylethyl-n-propylamine, methylethylisopropylamine, diethyl-n-propylamine, diethylisopropylamine, tri-n-propylamine, triisopropylamine, tri-n-butylamine, tri-tert-butylamine, etc.), and phenyl group-containing amines (dimethylphenylamine, methylethylphenylamine, diethylphenylamine, etc.). Among these, trialkylamines are preferred in terms of increasing conductivity, and it is more preferable to include at least one selected from the group consisting of trimethylamine, dimethylethylamine, methyldiethylamine, and triethylamine. Furthermore, secondary amines such as dialkylamines, primary amines such as monoalkylamines, and ammonia may also be used as the base component.

[0081] The liquid component may contain a salt of an acid component and a base component. The salt may be an inorganic salt and / or an organic salt. An organic salt is a salt in which at least one of the anion and the cation contains an organic substance. The organic salt is preferably an amine salt of an organic acid. Examples of organic salts include trimethylamine maleate, triethylamine borodisalicylate, triethylamine phthalate, ethyldimethylamine phthalate, mono-1,2,3,4-tetramethylimidazolinium phthalate, and mono-1,3-dimethyl-2-ethylimidazolinium phthalate.

[0082] To prevent dopant dedoping, the pH of the liquid component may be less than 7.0 or less than 5.0, or may be 1.0 or more, or 2.0 or more. The pH may be 1.0 or more and less than 7.0 (for example, in the range of 2.0 to 5.0).

[0083] The liquid component preferably contains a protic solvent, which makes it possible to particularly swell the conductive polymer layer.

[0084] The liquid component may contain a tertiary polyhydric alcohol as a protic solvent. The tertiary polyhydric alcohol preferably contains at least one selected from the group consisting of glycol compounds, glycerin compounds, and sugar alcohol compounds. The tertiary polyhydric alcohol may be the same compound as at least one of the first polyhydric alcohol and the second polyhydric alcohol. The first to third polyhydric alcohols may be the same compound.

[0085] (Other) The manufacturing method may include a step of sealing the capacitor element impregnated with the liquid component. For example, the capacitor element and the liquid component may be housed in a bottomed case, a sealing member may be placed in the opening of the bottomed case, a horizontal drawing process may be performed near the open end of the bottomed case, the open end may be crimped to the sealing member to form a curl, and a seat plate may be placed on the curled portion. In this manner, an electrolytic capacitor may be obtained. The electrolytic capacitor may then be subjected to an aging process while applying a rated voltage.

[0086] [Electrolytic Capacitor] An electrolytic capacitor according to an embodiment of the present disclosure includes a capacitor element and a liquid component. The capacitor element includes an anode foil having a dielectric layer, a cathode foil, a separator interposed between the anode foil and the cathode foil, a first conductive polymer component adhered to the separator, and a second conductive polymer component adhered to the anode foil and the cathode foil. The first conductive polymer component has a higher solubility in water than the second conductive polymer component. In other words, the first conductive polymer component adheres less to the separator surface than the second conductive polymer component adheres to the electrode foil surface. The electrolytic capacitor is obtained by a manufacturing method according to an embodiment of the present disclosure.

[0087] A separator having a first conductive polymer component adhered thereto and previously dried at 105° C. for 30 minutes is immersed in water at 25° C. for 10 minutes and then dried again at 105° C. for 30 minutes. The mass change rate R of the separator before and after immersion is preferably 20% by mass or more, or may be 30% by mass or more, or may be 30% by mass or more and 60% by mass or less. In this case, the adhesion of the first conductive polymer component to the separator surface is low enough that the first conductive polymer component can migrate into the second conductive polymer component so as to fill the gap between the electrode foil and the separator after impregnation with the liquid component.

[0088] At least one of the anode foil and the cathode foil to which the second conductive polymer component is attached is immersed in water at 25° C. for 10 minutes and then dried again at 105° C. for 30 minutes. The mass change rate R of at least one of the anode foil and the cathode foil before and after immersion is preferably less than 2% by mass, more preferably 1% by mass or less. In this case, the adhesion of the second conductive polymer component to the electrode foil surface is high enough that the second conductive polymer component remains firmly attached to the electrode foil surface even after impregnation with the liquid component.

[0089] The mass change rate R of the components (separator, anode foil, cathode foil) to which the conductive polymer component is attached before and after immersion can be determined as follows.

[0090] The component is dried at 105°C for 30 minutes, and then its mass M1 is measured. Next, the component is immersed in water at 25°C for 10 minutes, and then dried at 105°C for 30 minutes. The mass M2 of the dried component is measured. Using the obtained M1 and M2, the mass change rate R is calculated using the following formula (1).

[0091] Mass change rate R={(M1-M2) / M1}×100 (1) By applying the first treatment liquid to the separator surface, a first conductive polymer layer containing a first conductive polymer component is formed on the separator surface. The electrical conductivity of the first conductive polymer layer (first conductive polymer component) may be, for example, 0.1 S / cm or less, or 0.05 S / cm or less.

[0092] By applying the second treatment liquid to the surface of the electrode foil, a second conductive polymer layer containing a second conductive polymer component is formed on the surface of the electrode foil. The electrical conductivity of the second conductive polymer layer (second conductive polymer component) may be 0.5 S / cm or more, 3 S / cm or more, or 10 S / cm or more.

[0093] The electrical conductivity of the first conductive polymer layer is the electrical conductivity of the surface of a sample obtained by applying the treatment liquid used to form the first conductive polymer layer to a separator, thoroughly drying the coating, and removing the dispersion medium (or solvent).The electrical conductivity of the second conductive polymer layer is the electrical conductivity of the surface of a sample obtained by applying the treatment liquid used to form the second conductive polymer layer to an electrode foil, thoroughly drying the coating, and removing the dispersion medium (or solvent).The electrical conductivity is determined in accordance with the "Test Method for Resistivity of Conductive Plastics Using the Four-Probe Method" of Japanese Industrial Standards (JIS K 7194).The measuring instrument can be a low resistivity meter, a PSP probe, an ESP probe, or the like.

[0094] The mass of the liquid component is preferably 20 times or more the total mass of the first conductive polymer component and the second conductive polymer component (the secondA conductive polymer component and the secondB conductive polymer component). The mass of the liquid component is more preferably 80 times or more the total mass of the first conductive polymer component and the second conductive polymer component (the secondA conductive polymer component and the secondB conductive polymer component). In this case, the liquid component can be sufficiently impregnated between the separator having the first conductive polymer component attached to its surface and the electrode foil having the second conductive polymer component attached to its surface, allowing the first conductive polymer component to migrate to the second conductive polymer component. Furthermore, the liquid component can sufficiently protect the conductive polymer component.

[0095] The capacitor element may be a laminate formed by laminating, in this order, an anode foil having the second-A conductive polymer component attached thereto, a separator having the first conductive polymer component attached thereto, and a cathode foil having the second-B conductive polymer component attached thereto. Alternatively, the capacitor element may be a wound body formed by winding an anode foil having the second-A conductive polymer component attached thereto and a cathode foil having the second-B conductive polymer component attached thereto, with a separator having the first conductive polymer component attached thereto interposed therebetween. The electrolytic capacitor may include one capacitor element or multiple capacitor elements.

[0096] 1 is a cross-sectional view schematically illustrating an electrolytic capacitor according to an embodiment of the present disclosure, and FIG. 2 is a perspective view showing a partially developed wound body.

[0097] The electrolytic capacitor 200 includes a wound body 100 as a capacitor element. The wound body 100 is formed by winding an anode foil 10 having a second-A conductive polymer component attached thereto and a cathode foil 20 having a second-B conductive polymer component attached thereto, with a separator 30 having a first conductive polymer component attached thereto interposed between the anode foil 10 and the cathode foil 20. The wound body 100 is impregnated with a liquid component (not shown).

[0098] One end of each of lead tabs 50A and 50B is connected to anode foil 10 and cathode foil 20, respectively, and lead tabs 50A and 50B are wound to form wound body 100. Lead wires 60A and 60B are connected to the other ends of lead tabs 50A and 50B, respectively.

[0099] A stop tape 40 is disposed on the outer surface of the cathode foil 20 located at the outermost layer of the wound body 100, and the ends of the cathode foil 20 are fixed by the stop tape 40. When the anode foil 10 is prepared by cutting it from a large foil, the wound body 100 may further be subjected to a chemical conversion treatment in order to provide a dielectric layer on the cut surface.

[0100] Electrolytic capacitor 200 includes sealing member 212 that closes the opening of closed-end case 211, and seat plate 213 that covers sealing member 212. Wound body 100 is housed in closed-end case 211 so that lead wires 60A and 60B are located on the opening side of closed-end case 211. Lead wires 60A and 60B are led out from sealing member 212 and pass through seat plate 213. Closed-end case 211 can be made of a metal such as aluminum, stainless steel, copper, iron, or brass, or an alloy of these metals.

[0101] A sealing member 212 is placed at the opening of a bottomed case 211 that houses the wound body 100, the open end of the bottomed case 211 is crimped to the sealing member 212 to form a curl, and a seat plate 213 is placed on the curled portion, thereby sealing the wound body 100 inside the bottomed case 211. The sealing member 212 may be made of any insulating material, and is preferably an elastic material. As the elastic material, a material with excellent heat resistance, such as silicone rubber or fluororubber, is preferred.

[0102] EXAMPLES The present disclosure will be described in more detail below based on examples, but the present disclosure is not limited to these examples. Electrolytic capacitors of examples and comparative examples were fabricated according to the following procedure.

[0103] (Preparation of Components) An aluminum foil (thickness: 100 μm) was subjected to an etching treatment to roughen the surface of the aluminum foil. The roughened surface of the aluminum foil was subjected to a chemical conversion treatment to form a dielectric layer. In this way, an anode foil having a dielectric layer formed on its surface was obtained.

[0104] An aluminum foil (thickness: 50 μm) was subjected to an etching treatment to roughen the surface of the aluminum foil, thereby obtaining a cathode foil.

[0105] A nonwoven fabric (thickness: 50 μm) was prepared as a separator. The nonwoven fabric was composed of 50% by mass of synthetic fibers (25% by mass of polyester fibers and 25% by mass of aramid fibers) and 50% by mass of cellulose, and contained polyacrylamide as a paper strength agent. The density of the nonwoven fabric was 0.35 g / cm. ３ It was.

[0106] (Preparation of first treatment liquid) A first treatment liquid containing a first conductive polymer component, water, and a first polyhydric alcohol was prepared. The contents of each component in the first treatment liquid were as shown in Table 1.

[0107] (Preparation of 2A treatment liquid) A 2A treatment liquid containing a 2A conductive polymer component, water, and a 2A polyhydric alcohol was prepared. The contents of each component in the 2A treatment liquid were as shown in Table 2.

[0108] (Preparation of 2B treatment liquid) A 2B treatment liquid containing a 2B conductive polymer component, water, and a 2B polyhydric alcohol was prepared. The contents of each component in the 2B treatment liquid were as shown in Table 3.

[0109] Poly(3,4-ethylenedioxythiophene) (PEDOT) doped with polystyrene sulfonic acid (PSS) (hereinafter referred to as "PEDOT / PSS") was used for the first conductive polymer component, the secondA conductive polymer component, and the secondB conductive polymer component, respectively.

[0110] Ethylene glycol was used as the first polyhydric alcohol, the second A polyhydric alcohol, and the second B polyhydric alcohol.

[0111] (Formation of Conductive Polymer Layer) Using a gravure coater, the first treatment liquid was applied to both sides of the separator, and the coating was dried to form a first conductive polymer layer. The drying treatment was performed by heating the separator coated with the first treatment liquid at 125°C for 5 minutes. In this way, a separator S was produced in which a first conductive polymer layer was formed on the surface (in which the first conductive polymer component was adhered). Separators S1 to S7 were produced using the first treatment liquid shown in Table 1.

[0112]

[0113] Using a gravure coater, the 2A treatment liquid was applied to both sides of an anode foil having a dielectric layer, and the coating was dried to form a 2A conductive polymer layer. The drying treatment was performed by heating the anode foil coated with the 2A treatment liquid at 125°C for 5 minutes. In this manner, an anode foil P was produced, with a 2A conductive polymer layer formed on its surface (with the 2A conductive polymer component adhered thereto). Anode foils P1 to P7 were produced using the 2A treatment liquids shown in Table 2.

[0114]

[0115] Using the same method as for the anode foil, a 2B conductive polymer layer was formed on both sides of the cathode foil using the 2B treatment solution. In this way, cathode foil N was produced, with the 2B conductive polymer layer formed on the surface (with the 2B conductive polymer component adhered). Cathode foils N1 to N7 were produced using the 2B treatment solution shown in Table 3.

[0116]

[0117] (Fabrication of Capacitor Element) The anode foil P, cathode foil N, and separator S were each cut to a predetermined size. Anode lead tabs and cathode lead tabs were connected to the anode foil P and cathode foil N. Next, the anode foil P and cathode foil N were wound with the separator S interposed between the anode foil P and cathode foil N. An anode lead wire and a cathode lead wire were connected to the ends of each lead tab protruding from the wound body. The resulting wound body was again subjected to chemical conversion treatment, and a dielectric layer was formed on the end surface of the anode foil (aluminum foil). The ends of the outer surface of the wound body were fixed with winding tape. In this way, a capacitor element was obtained.

[0118] (Impregnation of Liquid Component) Triethylamine phthalate was dissolved in ethylene glycol at a concentration of 25% by mass to prepare an electrolyte solution. The capacitor element was immersed in the electrolyte solution for 5 minutes in a reduced pressure atmosphere (40 kPa). In this way, the capacitor element (laminate) was impregnated with the electrolyte solution.

[0119] (Sealing of Capacitor Element) The capacitor element impregnated with the electrolytic solution was sealed to produce an electrolytic capacitor as shown in Fig. 1. Then, aging was performed at 95°C for 90 minutes while applying a voltage. In this way, an electrolytic capacitor was obtained.

[0120] In producing the above capacitor elements, electrolytic capacitors were obtained using the components (separator S, anode foil P, cathode foil N) shown in Tables 4 to 7. Note that A1 to A4 in Table 4, A11 to A12 in Table 5, and A21 to 22 in Table 6 are examples, and B1 to B3 in Table 4, B11 to B14 in Table 5, B21 to B24 in Table 6, and B31 to B37 in Table 7 are comparative examples.

[0121]

[0122]

[0123]

[0124]

[0125] [Evaluation of Each Component] (Mass Change Rate of Each Component Before and After Immersion in Water) The mass change rate R of each component, i.e., the anode foil P, the cathode foil N, and the separator S, before and after immersion in water was determined by the method described above. The determined mass change rates R are shown in Tables 1 to 3.

[0126] S1 to S4, which were produced using a first treatment liquid with a first polyhydric alcohol content of less than 10% by mass (5% by mass or less), had a mass change rate R of 20% by mass or more, which was larger than S5 to S7, which were produced using a first treatment liquid with a first polyhydric alcohol content of 10% by mass or more, indicating that the first conductive polymer component is more likely to migrate into the secondA conductive polymer component and the secondB conductive polymer component when the liquid component is impregnated into the capacitor element.

[0127] P5 to P7, which were produced using a second A treatment liquid with a second A polyhydric alcohol content of 10% by mass or more, had a mass change rate R of less than 2% by mass, which was smaller than P1 to P4, which were produced using a second A treatment liquid with a second A polyhydric alcohol content of less than 10% by mass, indicating high adhesion of the second A conductive polymer component.

[0128] In N5 to N7, which were produced using a second B treatment liquid in which the content of the second B polyhydric alcohol was 10% by mass or more, the mass change rate R was less than 2% by mass, which was smaller than that of N1 to N4, which were produced using a second B treatment liquid in which the content of the second B polyhydric alcohol was less than 10% by mass, indicating that the adhesion of the second B conductive polymer component was high.

[0129] In addition, in S1 to S4, the mass of the first polyhydric alcohol in the first treatment liquid was less than five times the mass of the first conductive polymer component. In P5 to P7, the mass of the second A polyhydric alcohol in the second A treatment liquid was five times or more the mass of the second A conductive polymer component. In N5 to N7, the mass of the second B polyhydric alcohol in the second B treatment liquid was five times or more the mass of the second B conductive polymer component.

[0130] (Electrical Conductivity of Conductive Polymer Layer Formed on the Surface of Each Component) The electrical conductivity of the conductive polymer layer formed on the surface of each component was determined by the method described above. The determined electrical conductivities are shown in Tables 1 to 3.

[0131] In S1 to S4, which were produced using a first treatment liquid in which the content of the first polyhydric alcohol was less than 10% by mass (5% by mass or less), the electrical conductivity of the first conductive polymer layer formed on the surface of the separator was lower, at 0.1 S / cm or less, compared to S5 to S7, which were produced using a first treatment liquid in which the content of the first polyhydric alcohol was 10% by mass or more.

[0132] In P5 to P7, which were produced using a 2A treatment liquid in which the content of the 2A polyhydric alcohol was 10% by mass or more, the electrical conductivity of the 2A conductive polymer layer formed on the surface of the anode foil was higher, at 0.5 S / cm or more, compared to P1 to P4, which were produced using a 2A treatment liquid in which the content of the 2A polyhydric alcohol was less than 10% by mass.

[0133] In N5 to N7, which were produced using a 2B treatment liquid in which the content of the 2B polyhydric alcohol was 10% by mass or more, the electrical conductivity of the 2B conductive polymer layer formed on the surface of the cathode foil was higher, at 0.5 S / cm or more, compared to N1 to N4, which were produced using a 2B treatment liquid in which the content of the 2B polyhydric alcohol was less than 10% by mass.

[0134] [Evaluation of Electrolytic Capacitor: Measurement of ESR] The ESR (mΩ) of the electrolytic capacitor was measured at frequencies of 100 kHz and 120 Hz using a four-terminal LCR meter in an environment of 20° C. The measurement results are shown in Tables 4 to 7.

[0135] A1 to A4, A11 to A12, and A21 to 22 exhibited lower ESR in both the high-frequency and low-frequency regions than B1 to B3, B11 to B13, B21 to B23, and B31 to B37. A1 to A4, A11 to A12, and A21 to 22 used a separator S produced using a first treatment solution containing less than 10% by mass of a first polyhydric alcohol, and an anode foil P and a cathode foil N produced using a second treatment solution containing 10% by mass or more of a second polyhydric alcohol.

[0136] In addition, in A1 to A4, A11 to A12, and A21 to 22, the mass of the liquid component was 20 times or more the total mass of the first conductive polymer component, the secondA conductive polymer component, and the secondB conductive polymer component.

[0137] <<Supplementary Note>> The above description of the embodiment discloses the following techniques.

[0138] (Technology 1) A capacitor element manufacturing method includes the steps of: preparing an anode foil, a cathode foil, and a separator each having a dielectric layer; preparing a first treatment liquid containing a first conductive polymer component; preparing a second treatment liquid containing a second conductive polymer component; applying the first treatment liquid to the separator to adhere the first conductive polymer component; applying the second treatment liquid to at least one of the anode foil and the cathode foil to adhere the second conductive polymer component; after the step of adhering the second conductive polymer component, sequentially stacking the anode foil, the separator to which the first conductive polymer component has been adhered, and the cathode foil to form a capacitor element; and impregnating the capacitor element with a liquid component; wherein the first treatment liquid contains or is substantially free of a first polyhydric alcohol; the content of the first polyhydric alcohol in the first treatment liquid is 0% by mass or more and less than 10% by mass; and The method for manufacturing an electrolytic capacitor, wherein the content of the second polyhydric alcohol in the second treatment liquid is 10 mass % or more.

[0139] (Technology 2) The method for producing an electrolytic capacitor according to Technology 1, wherein the step of impregnating with the liquid component includes a step of causing the first conductive polymer component to migrate into the second conductive polymer component to increase the conductive paths between the second conductive polymer component and the first conductive polymer component.

[0140] (Technology 3) The method for manufacturing an electrolytic capacitor according to Technology 1 or 2, wherein the first polyhydric alcohol and the second polyhydric alcohol each contain at least one selected from the group consisting of a glycol compound, a glycerin compound, and a sugar alcohol compound.

[0141] (Technology 4) The method for producing an electrolytic capacitor according to any one of Technologies 1 to 3, wherein the liquid component contains a tertiary polyhydric alcohol.

[0142] (Technology 5) The method for producing an electrolytic capacitor according to Technology 4, wherein the third polyhydric alcohol includes at least one selected from the group consisting of a glycol compound, a glycerin compound, and a sugar alcohol compound.

[0143] (Technology 6) The method for producing an electrolytic capacitor according to any one of Technologies 1 to 5, wherein the liquid component contains an amine salt of an organic acid.

[0144] (Technology 7) The method for manufacturing an electrolytic capacitor according to any one of Technologies 1 to 6, wherein in the first treatment solution, the mass of the first polyhydric alcohol is less than five times the mass of the first conductive polymer component.

[0145] (Technology 8) The method for manufacturing an electrolytic capacitor according to any one of Technologies 1 to 7, wherein in the second treatment solution, the mass of the second polyhydric alcohol is 5 times or more and 25 times or less the mass of the second conductive polymer component.

[0146] (Technology 9) An electrolytic capacitor comprising: a capacitor element; and a liquid component, wherein the capacitor element comprises: an anode foil having a dielectric layer; a cathode foil; a separator interposed between the anode foil and the cathode foil; a first conductive polymer component adhered to the separator; and a second conductive polymer component adhered to at least one of the anode foil and the cathode foil, wherein the first conductive polymer component has a higher solubility in water than the second conductive polymer component.

[0147] (Technology 10) An electrolytic capacitor according to Technology 9, wherein the separator having the first conductive polymer component adhered thereto and previously dried at 105°C for 30 minutes is immersed in water at 25°C for 10 minutes and then dried again at 105°C for 30 minutes, the mass change rate of the separator before and after the immersion is 20% by mass or more; and at least one of the anode foil and the cathode foil having the second conductive polymer component adhered thereto and previously dried at 105°C for 30 minutes is immersed in water at 25°C for 10 minutes and then dried again at 105°C for 30 minutes, the mass change rate of at least one of the anode foil and the cathode foil before and after the immersion is less than 2% by mass.

[0148] (Technology 11) The electrolytic capacitor according to Technology 9 or 10, wherein the first conductive polymer component has an electrical conductivity of 0.1 S / cm or less, and the second conductive polymer component has an electrical conductivity of 0.5 S / cm or more.

[0149] (Technology 12) The electrolytic capacitor according to Technology 9, wherein the mass of the liquid component is 20 times or more the total mass of the first conductive polymer component and the second conductive polymer component.

[0150] (Technology 13) A first treatment liquid is applied to a separator constituting a capacitor element of an electrolytic capacitor including a capacitor element and a liquid component, the first treatment liquid containing a first conductive polymer component and containing or substantially not containing a first polyhydric alcohol, the content of the first polyhydric alcohol in the first treatment liquid being 0 mass % or more and less than 10 mass %, and the first conductive polymer component adhered to the separator by application of the first treatment liquid to the separator migrates to another adjacent conductive polymer component when the liquid component is impregnated into the capacitor element.

[0151] (Technology 14) A second treatment liquid is used together with the first treatment liquid according to Technology 13, and is applied to at least one of an anode foil and a cathode foil constituting a capacitor element of an electrolytic capacitor including a capacitor element and a liquid component, the second treatment liquid including a second conductive polymer component and a second polyhydric alcohol, and the content of the second polyhydric alcohol in the second treatment liquid is 10 mass % or more.

[0152] The method for manufacturing an electrolytic capacitor according to the present disclosure is suitable for use in electrolytic capacitors that require a low ESR.

[0153] 10: Anode foil, 20: Cathode foil, 30: Separator, 40: Winding tape, 50A, 50B: Lead tabs, 60A, 60B: Lead wires, 100: Wound body, 200: Electrolytic capacitor, 211: Bottomed case, 212: Sealing member, 213: Seat plate

Claims

1. providing an anode foil, a cathode foil, and a separator, each having a dielectric layer; preparing a first treatment liquid containing a first conductive polymer component; preparing a second treatment liquid containing a second conductive polymer component; applying the first treatment liquid to the separator to adhere the first conductive polymer component; applying the second treatment liquid to at least one of the anode foil and the cathode foil to adhere the second conductive polymer component; a step of laminating the anode foil, the separator to which the first conductive polymer component has been attached, and the cathode foil in this order to produce a capacitor element, after the step of attaching the second conductive polymer component; impregnating the capacitor element with a liquid component; the first treatment liquid contains or is substantially free of a first polyhydric alcohol; a content of the first polyhydric alcohol in the first treatment liquid is 0% by mass or more and less than 10% by mass; the second treatment liquid contains a second polyhydric alcohol, The method for manufacturing an electrolytic capacitor, wherein the content of the second polyhydric alcohol in the second treatment liquid is 10 mass % or more.

2. A method for manufacturing an electrolytic capacitor as described in claim 1, wherein the process of impregnating the capacitor element with the liquid component includes a process of migrating the first conductive polymer component into the second conductive polymer component to increase the conductive path between the second conductive polymer component and the first conductive polymer component.

3. 2. The method for manufacturing an electrolytic capacitor according to claim 1, wherein the first polyhydric alcohol and the second polyhydric alcohol each contain at least one compound selected from the group consisting of a glycol compound, a glycerin compound, and a sugar alcohol compound.

4. The method for manufacturing an electrolytic capacitor according to claim 1 , wherein the liquid component includes a tertiary polyhydric alcohol.

5. 5. The method for producing an electrolytic capacitor according to claim 4, wherein the third polyhydric alcohol includes at least one selected from the group consisting of a glycol compound, a glycerin compound, and a sugar alcohol compound.

6. The method for producing an electrolytic capacitor according to claim 4 , wherein the liquid component includes an amine salt of an organic acid.

7. 2. The method for manufacturing an electrolytic capacitor according to claim 1, wherein the mass of the first polyhydric alcohol in the first treatment solution is less than five times the mass of the first conductive polymer component.

8. 2. The method for manufacturing an electrolytic capacitor according to claim 1, wherein the mass of the second polyhydric alcohol in the second treatment liquid is 5 times or more and 25 times or less the mass of the second conductive polymer component.

9. a capacitor element and a liquid component, The capacitor element is an anode foil having a dielectric layer; A cathode foil; a separator interposed between the anode foil and the cathode foil; a first conductive polymer component attached to the separator; a second conductive polymer component attached to at least one of the anode foil and the cathode foil; Equipped with The electrolytic capacitor, wherein the first conductive polymer component has higher solubility in water than the second conductive polymer component.

10. the separator having the first conductive polymer component adhered thereto and previously dried at 105°C for 30 minutes is immersed in water at 25°C for 10 minutes, and then dried again at 105°C for 30 minutes, the mass change rate R of the separator before and after the immersion is 20 mass% or more, 10. The electrolytic capacitor according to claim 9, wherein at least one of the anode foil and the cathode foil having the second conductive polymer component adhered thereto is immersed in water at 25°C for 10 minutes and then dried again at 105°C for 30 minutes, and a mass change rate R of at least one of the anode foil and the cathode foil before and after the immersion is less than 2 mass%.

11. the electrical conductivity of the first conductive polymer component is 0.1 S / cm or less; 10. The electrolytic capacitor according to claim 9, wherein the second conductive polymer component has an electrical conductivity of 0.5 S / cm or more.

12. 10. The electrolytic capacitor according to claim 9, wherein the mass of the liquid component is 20 times or more the total mass of the first conductive polymer component and the second conductive polymer component.

13. a first treatment liquid for forming an electrolytic capacitor, the first treatment liquid including a capacitor element and a liquid component, the first treatment liquid being applied to a separator constituting the capacitor element; a first conductive polymer component; containing or substantially free of a first polyhydric alcohol; a content of the first polyhydric alcohol in the first treatment liquid is 0% by mass or more and less than 10% by mass; The first conductive polymer component adhered to the separator by applying the first treatment liquid to the separator migrates to another adjacent conductive polymer component when the capacitor element is impregnated with the liquid component.

14. A second treatment liquid for forming an electrolytic capacitor comprising a capacitor element and a liquid component, said second treatment liquid being used together with the first treatment liquid of claim 13 and being applied to at least one of an anode foil and a cathode foil constituting said capacitor element; a second conductive polymer component and a second polyhydric alcohol; The second treatment liquid has a content of the second polyhydric alcohol of 10% by mass or more.