Electrolytic capacitor

Abstract

To provide an electrolytic capacitor and an electrolytic capacitor module having excellent heat resistance.SOLUTION: An electrolytic capacitor 100 includes a capacitor element 10 and a liquid component. The capacitor element includes an anode body including a dielectric layer on its surface, and a conductive polymer covering a part of the dielectric layer. The liquid component includes a sugar alcohol component and a polyalkylene glycol component as a solvent, and a solute. The sugar alcohol component includes at least one selected from the group consisting of a sugar alcohol having four or more hydroxy groups and a derivative thereof. A content of the sugar alcohol component in the liquid component is 8.7 mass% or more. A content (mass%) of the polyalkylene glycol component in the liquid component is larger than the content (mass%) of the sugar alcohol component in the liquid component. Viscosity at 20°C of the liquid component is 200 mPa s or more.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to an electrolytic capacitor, a method for manufacturing the same, and an electrolytic capacitor module.

Background Art

[0002] As a capacitor that is small, has a large capacitance, and has a low ESR (equivalent series resistance), an electrolytic capacitor including an anode body having a dielectric layer, a conductive polymer covering at least a part of the dielectric layer, and an electrolytic solution is regarded as promising. As the electrolytic solution, a liquid component such as a non-aqueous solvent or a solution in which a solute is dissolved in a non-aqueous solvent is used.

[0003] Patent Document 1 proposes using an electrolytic solution containing a sugar alcohol derivative having a valency of four or more in a solid electrolytic capacitor.

[0004] Patent Document 2 proposes filling a void in a capacitor element in which a solid electrolyte layer containing sorbitol or sorbitol and a polyhydric alcohol is formed with an electrolytic solution containing ethylene glycol. The electrolytic solution may contain sorbitol.

[0005] Patent Document 3 includes a first introduction step of introducing a dispersion liquid containing a particulate conductive polymer compound and a first water-soluble compound into a capacitor element, and a liquid polyethylene glycol, water, and a second water-soluble compound so as to surround the solid electrolyte layer formed by the first introduction step. In the production of a solid electrolytic capacitor having a second introduction step of introducing a water-soluble polymer solution containing the same, in the second introduction step, a water-soluble polymer solution not containing a particulate conductive polymer compound is used, and the same substance as the first water-soluble compound is used as the second water-soluble compound. Here, the first water-soluble compound is one having a molecular weight of 100 or more and less than 200 and having four or more hydroxyl groups, diglycerin, or both.

Prior Art Documents

Patent Documents

[0006] Patent Document 1 Japanese Patent Application Laid-Open No. 2018-110233 Patent Document 2 Japanese Patent Application Laid-Open No. 2014-123685 Patent Document 3 Japanese Patent No. 6535409 SUMMARY OF THE INVENTION PROBLEMS TO BE SOLVED BY THE INVENTION

[0007] Since electrolytic capacitors may be used in a high-temperature environment depending on the application, high heat resistance is required. MEANS FOR SOLVING THE PROBLEMS

[0008] [Technology 1] One aspect of the present disclosure includes a capacitor element and a liquid component, The capacitor element includes an anode body having a dielectric layer on a surface thereof, and a conductive polymer covering a part of the dielectric layer, The liquid component includes a sugar alcohol component and a polyalkylene glycol component, The sugar alcohol component includes at least one selected from the group consisting of sugar alcohols having four or more hydroxy groups and derivatives thereof, and relates to an electrolytic capacitor. [Technology 2] In the electrolytic capacitor according to Technology 1, the content of the sugar alcohol component in the liquid component is 5% by mass or more and 70% by mass or less. [Technology 3] In the electrolytic capacitor according to Technology 1 or 2, the content of the polyalkylene glycol component in the liquid component is more than the content of the sugar alcohol component in the liquid component. [Technology 4] The electrolytic capacitor according to any one of Technologies 1 to 3, wherein the sugar alcohol component includes at least one selected from the group consisting of mannitol, sorbitol, erythritol, pentaerythritol, and derivatives thereof. [Technology 5] The content of the polyalkylene glycol component in the liquid component is 30% by mass or more and 95% by mass or less, and the electrolytic capacitor according to any one of Technologies 1 to 4. [Technology 6] The weight average molecular weight of the polyalkylene glycol component is 200 or more and 2000 or less, and the electrolytic capacitor according to any one of Technologies 1 to 5. [Technology 7] The liquid component contains a solute at a concentration of 0.5% by mass or more, and the electrolytic capacitor according to any one of Technologies 1 to 6. [Technology 8] The viscosity of the liquid component at 20 °C is 200 mPa·s or more, and the electrolytic capacitor according to any one of Technologies 1 to 7. [Technology 9] A container having an opening and containing the capacitor element and the liquid component, A sealing body for sealing the opening, and further comprising, The sealing body contains an elastic polymer, The ratio of the elastic polymer in the sealing body is 10% by mass or more, and the electrolytic capacitor according to any one of Technologies 1 to 8. [Technology 10] The elastic polymer is cross-linked with at least one cross-linking agent selected from the group consisting of phenolic resins and peroxides, and the electrolytic capacitor according to Technology 9. [Technology 11] Guaranteed to be used at a temperature of 120 °C for 2000 hours or more, and the electrolytic capacitor according to any one of Technologies 1 to 10.

[0009] [Technology 12] Another aspect of the present disclosure relates to an electrolytic capacitor module including a plurality of electrolytic capacitors according to any one of Technologies 1 to 11 connected in parallel. [Technology 13] The allowable current is 20 A or more, and the electrolytic capacitor module according to Technology 12.

[0010] [Technology 14] Still another aspect of the present disclosure is a method for manufacturing an electrolytic capacitor including a capacitor element having a dielectric layer on a surface and a conductive polymer covering a part of the dielectric layer, and a liquid component, A step of preparing a liquid component containing a sugar alcohol component and a polyalkylene glycol component; A conductive polymer impregnation step of impregnating the dielectric layer with the conductive polymer; After the conductive polymer impregnation step, a liquid component impregnation step of impregnating the liquid component into the capacitor element, The sugar alcohol component includes at least one selected from the group consisting of sugar alcohols having four or more hydroxy groups and derivatives thereof, and relates to a method for manufacturing an electrolytic capacitor. [Technical 15] The preparation step includes a step of dissolving the sugar alcohol component in the polyalkylene glycol component, and relates to a method for manufacturing an electrolytic capacitor according to Technical 14. [Technical 16] Before the liquid component impregnation step, a step of making the viscosity of the liquid component less than 200 mPa·s, and relates to a method for manufacturing an electrolytic capacitor according to Technical 14 or 15.

Effects of the Invention

[0011] An electrolytic capacitor and an electrolytic capacitor module excellent in heat resistance can be provided.

Brief Description of the Drawings

[0012]

Figure 1

Figure 2

Modes for Carrying Out the Invention

[0013] When an electrolytic capacitor having a liquid component containing a non-aqueous solvent is used in a high-temperature environment, the non-aqueous solvent is likely to evaporate, and it is difficult to obtain sufficient durability. Therefore, it is preferable to use a liquid component containing a non-aqueous solvent having a relatively high boiling point. However, when the boiling point of the non-aqueous solvent is high, the viscosity of the liquid component increases, and it may be difficult to impregnate the capacitor element. In addition, when such a non-aqueous solvent is used, the dissociability of the solute may decrease, and it may be difficult to ensure the characteristics of the electrolytic capacitor. Further, when the number of consecutive carbon atoms in the molecular chain of the non-aqueous solvent increases, the affinity with the elastic polymer contained in the sealing body increases, and the sealing body is likely to swell with the non-aqueous solvent. When an electrolytic capacitor with a swollen sealing body by a non-aqueous solvent is exposed to a high-temperature environment, the deterioration of the sealing body progresses and the durability decreases. Conventionally, various non-aqueous solvents have been cited as those used in the liquid component of the electrolytic capacitor, but it is very difficult to obtain a liquid component having an excellent balance of the above characteristics.

[0014] In the electrolytic capacitor according to one aspect of the present disclosure, in an electrolytic capacitor including a capacitor element containing a conductive polymer, a liquid component containing a sugar alcohol component and a polyalkylene glycol component is used. Here, the sugar alcohol component includes at least one selected from the group consisting of sugar alcohols having four or more hydroxy groups and derivatives thereof. Such a sugar alcohol component has high hydrophilicity but low solubility in non-aqueous solvents, and is actually difficult to use in the liquid component of an electrolytic capacitor. However, by combining such a sugar alcohol component and a polyalkylene glycol component, the dissolution of the sugar alcohol component becomes easy, the viscosity of the liquid component can be suppressed to be relatively low, and high dissociability of the solute can be ensured. Therefore, it can be used as the liquid component of an electrolytic capacitor. And such a liquid component, by containing a sugar alcohol component, is difficult to volatilize even in a high-temperature environment, and is difficult to swell the sealing body. Therefore, high heat resistance of the electrolytic capacitor can be ensured. Further, a sugar alcohol or a derivative thereof having four or more hydroxy groups can enhance the orientation of the conductive polymer contained in the capacitor element as compared with glycerin or the like, and thereby enhance the conductivity of the conductive polymer. Also, generally, when a component having many hydroxy groups is used for the liquid component, it becomes easy to permeate the sealing body. However, by using the sugar alcohol component as described above, a large amount of the sugar alcohol component remains in the liquid component even in a high-temperature environment. Therefore, high orientation of the conductive polymer can be maintained.

[0015] Hereinafter, the configuration of the electrolytic capacitor and the method for manufacturing the electrolytic capacitor will be described in more detail.

[0016] [Electrolytic Capacitor] The electrolytic capacitor includes a capacitor element and a liquid component. The electrolytic capacitor usually includes a container that houses the capacitor element and the liquid component, and a sealing body that seals the container.

[0017] (Liquid Component) (Sugar Alcohol Component) The sugar alcohol component contains at least one selected from the group consisting of sugar alcohols having four or more hydroxy groups and their derivatives (hereinafter sometimes referred to as the first sugar alcohol component). The sugar alcohol component may contain a sugar alcohol component other than the first sugar alcohol component (the second sugar alcohol component). From the viewpoint of easily ensuring the effects of the sugar alcohol component, the ratio of the first sugar alcohol component in the sugar alcohol component is preferably 50% by mass or more, and may be 75% by mass or more or 90% by mass or more. The sugar alcohol component may be composed only of the first sugar alcohol component.

[0018] Examples of the sugar alcohol having four or more hydroxy groups (hereinafter sometimes referred to as the first sugar alcohol) include monosaccharide alcohols and disaccharide alcohols. Examples of the first sugar alcohol include sorbitol, mannitol, erythritol, pentaerythritol, trehalose, arabinitol, ribitol, xylitol, galactitol, rhamnitol, isomaltose, maltitol, lactitol, palatinose, and their reduced forms (for example, reduced palatinose).

[0019] The number of hydroxy groups of the first sugar alcohol may be, for example, 10 or less, or 8 or less.

[0020] The number of hydroxy groups of the derivative of the first sugar alcohol is not particularly limited. The derivative may not have a hydroxy group, or may have more hydroxy groups than the corresponding first sugar alcohol. The number of hydroxy groups of the derivative may be, for example, 0 to 10, 0 to 8, 1 to 8, or 2 to 8. Examples of the derivative include esters in which at least a part of the hydroxy groups of the first sugar alcohol are esterified, alkylene oxide adducts of the first sugar alcohol, and the like. Examples of the ester include organic acid esters (such as acetylated sugar alcohol). More specifically, examples of the alkylene oxide adduct include an adduct in which one molecule of alkylene oxide is added to one hydroxy group for at least a part of the hydroxy groups. Examples of the alkylene oxide include C 2-4 alkylene oxide, and C 2-3 alkylene oxide or ethylene oxide is preferred. When the alkylene oxide adduct contains a plurality of alkylene oxide units, at least two alkylene oxide units may be of the same type, or the types of all alkylene oxide units may be different.

[0021] The liquid component may contain one type of first sugar alcohol component or two or more types of first sugar alcohol components. From the viewpoint of facilitating the orientation of the conductive polymer, it is preferable to use a first sugar alcohol component having hydroxy groups on at least two adjacent carbon atoms. Examples of the first sugar alcohol component include mannitol, sorbitol, erythritol, pentaerythritol, and derivatives thereof. As the derivative, an alkylene oxide adduct is preferred. These first sugar alcohol components are easy to swell the conductive polymer and easy to orient the conductive polymer. Therefore, the film repair effect of the dielectric layer can be enhanced and the ESR can be reduced.

[0022] Examples of the second sugar alcohol component include xylitol or its derivatives. Examples of xylitol include glycerin. Examples of derivatives include esters in which at least some of the hydroxy groups of xylitol are esterified, adducts in which alkylene oxide is added to at least some of the hydroxy groups of xylitol, polyglycerin or its derivatives. Note that polyglycerin or its derivatives are generally not classified as sugar alcohols, but in this specification, for convenience, these are included in the second sugar alcohol component. Examples of polyglycerin include those having a repeating number of glycerin of 2 or more and 12 or less. Examples of derivatives of polyglycerin include esters in which at least some of the hydroxy groups are esterified and adducts in which alkylene oxide is added to at least some of the hydroxy groups. For esters and alkylene oxide adducts, reference can be made to the description of derivatives of the first sugar alcohol component. The liquid component may contain one kind of the second sugar alcohol component or two or more kinds.

[0023] The content of the sugar alcohol component in the liquid component is, for example, 5% by mass or more, preferably 10% by mass or more, and may be 15% by mass or more, 20% by mass or more, 25% by mass or more, or 30% by mass or more. When the content of the sugar alcohol component is in such a range, in addition to being easily swollen by the conductive polymer, the orientation of the conductive polymer is easily enhanced. Further, by relatively lowering the ratio of other components, the effect of suppressing the swelling of the sealing body by the liquid component is enhanced. The content of the sugar alcohol component in the liquid component is preferably 70% by mass or less, more preferably 50% by mass or less, and may be 40% by mass or less, 35% by mass or less, or 30% by mass or less. When the content of the sugar alcohol component is in such a range, the viscosity of the liquid component can be kept low and it is easy to ensure high dissociability of the solute. These lower limit values and upper limit values can be arbitrarily combined.

[0024] (Polyalkylene glycol component) As the polyalkylene glycol component, any component having a repeating structure of alkylene oxide may be used. Examples of the alkylene oxide include C 2-4 alkylene oxide, and C 2-3 alkylene oxide may also be used. Specific examples of the alkylene oxide include ethylene oxide, propylene oxide, trimethylene oxide, butylene oxide and the like. The polyalkylene glycol component may contain one kind of alkylene oxide unit, or may contain two or more kinds of alkylene oxide units. The polyalkylene glycol component containing two or more kinds of alkylene oxide units may contain, for example, an ethylene oxide unit and a C 3-4 alkylene oxide unit. When a polyalkylene glycol component containing two or more kinds of alkylene oxide units is used, the effect of reducing the viscosity of the liquid component is enhanced.

[0025] Examples of the polyalkylene glycol component include polyalkylene glycol, a copolymer containing two or more kinds of alkylene oxide units, and a polyalkylene oxide adduct of a polyhydric alcohol. Examples of the polyhydric alcohol include glycerin, trimethylolpropane, and the sugar alcohols exemplified for the first sugar alcohol. In the polyalkylene oxide adduct, two or more polyalkylene oxide chains may be the same polyalkylene oxide chain, or all the polyalkylene oxide chains may be different.

[0026] The liquid component may contain one kind of polyalkylene glycol component, or may contain two or more kinds of polyalkylene glycol components.

[0027] The weight average molecular weight (Mw) of the polyalkylene glycol component is, for example, 150 or more, preferably 200 or more. When Mw is within such a range, it is easy to dissolve the sugar alcohol component, and even though the liquid component contains the sugar alcohol component, the viscosity of the liquid component can be kept low. In addition, the effect of suppressing the volatilization of the liquid component can be enhanced. Mw is, for example, 3000 or less, and may be 2000 or less, 1000 or less, or may be 800 or less, 600 or less. When Mw is within such a range, the viscosity of the liquid component can be further suppressed to be lower. These lower limit values and upper limit values can be arbitrarily combined.

[0028] In addition, in this specification, the weight average molecular weight (Mw) is a value in terms of polystyrene measured by gel permeation chromatography (GPC). Note that GPC is usually measured using a polystyrene gel column and water / methanol (volume ratio 8 / 2) as the mobile phase.

[0029] The content of the polyalkylene glycol component in the liquid component is, for example, 30% by mass or more, preferably 50% by mass or more, 60% by mass or more, 65% by mass or more, or 70% by mass or more. In this case, the solubility of the sugar alcohol component can be increased, and even though the sugar alcohol component is contained, the viscosity of the liquid component can be kept lower. The content of the polyalkylene glycol component in the liquid component is, for example, 95% by mass or less, preferably 90% by mass or less, and may be 85% by mass or less, 80% by mass or less, 75% by mass or less, 70% by mass or less, 60% by mass or less, or 50% by mass or less. In this case, even when an electrolytic capacitor is used in a high-temperature environment, swelling of the sealing body due to the liquid component can be more effectively suppressed. These lower limit values and upper limit values can be arbitrarily combined.

[0030] The content of the polyalkylene glycol component in the liquid component is preferably more than the content of the sugar alcohol component. Thereby, it becomes easy to dissolve the sugar alcohol component, and it becomes easy to ensure high dissociation of the solute in the liquid component, so that the film repair effect of the dielectric layer can be enhanced.

[0031] (Non-aqueous solvent) The liquid component may contain a non-aqueous solvent other than the sugar alcohol component and the polyalkylene glycol component. Examples of the non-aqueous solvent include sulfone compounds, lactone compounds, carbonate compounds, and polyhydric alcohols other than the sugar alcohol component and the polyalkylene glycol component.

[0032] Examples of the sulfone compound include sulfolane, dimethyl sulfoxide, and diethyl sulfoxide. Examples of the lactone compound include γ-butyrolactone and γ-valerolactone. Examples of the carbonate compound include dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, ethylene carbonate, propylene carbonate, and fluoroethylene carbonate. Examples of the polyhydric alcohol include alkylene glycols (such as ethylene glycol and propylene glycol) and trimethylolpropane.

[0033] The liquid component may contain one of these non-aqueous solvents or may contain two or more thereof.

[0034] From the viewpoint of enhancing the effect of suppressing the swelling of the sealing body by the liquid component, the content of such a non-aqueous solvent in the liquid component is preferably 10% by mass or less, more preferably 5% by mass or less or 1% by mass or less.

[0035] (Solute) The liquid component may contain a solute. Examples of the solute include an acid component and a base component. The liquid component preferably contains at least an acid component. When the conductive polymer component contains a dopant, the acid component in the electrolyte suppresses the dedoping phenomenon of the dopant and stabilizes the conductivity of each polymer component. Further, even when the dopant is dedoped from the conductive polymer component, the acid component of the electrolyte is redoped at the site of the dedoping trace, so that the ESR is likely to be maintained low. The electrolyte may contain a base component together with the acid component. At least a part of the acid component is neutralized by the base component. Therefore, while increasing the concentration of the acid component, corrosion of the electrode by the acid component can be suppressed.

[0036] Examples of the acid component include carboxylic acids, sulfur-containing acids (such as sulfuric acid and sulfonic acid), boron-containing acids (such as boric acid, halogenated boric acid (such as tetrafluoroboric acid), or partial esters thereof), phosphorus-containing acids (such as phosphoric acid, halogenated phosphoric acid (such as hexafluorophosphoric acid), phosphonic acid, phosphinic acid, or partial esters thereof), nitric acid, and nitrous acid. As the acid component, a condensate of a carboxylic acid and an inorganic acid (such as boric acid and phosphoric acid) may be used. The liquid component may contain one kind of acid component or two or more kinds of acid components.

[0037] As the acid component, carboxylic acids, sulfonic acids, condensates of carboxylic acids and inorganic acids, etc. are preferable. Examples of the sulfonic acid include aliphatic sulfonic acids having 1 to 30 carbon atoms and aromatic sulfonic acids having 6 to 30 carbon atoms. Examples of the carboxylic acid include aliphatic carboxylic acids and aromatic carboxylic acids. Among them, aromatic carboxylic acids are relatively stable. Also, polycarboxylic acids having two or more hydroxy groups are preferable. Specifically, as the aromatic carboxylic acid, phthalic acid, pyromellitic acid, etc. can be used. Among them, phthalic acid is preferable.

[0038] As the condensate of a carboxylic acid and an inorganic acid, a condensate of a carboxylic acid and boric acid is preferable. Specifically, as such a condensate, borodisalicylic acid, borodiglycolic acid, borodioxalic acid, etc. can be used.

[0039] Examples of the basic component include ammonia, amines (specifically, primary amines, secondary amines, and tertiary amines), quaternary ammonium compounds, and amidinium compounds. The liquid component may contain one kind of the basic component or two or more kinds thereof.

[0040] The amine may be aliphatic, aromatic, or heterocyclic. Examples of the amine include methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, ethylenediamine, N,N-diisopropylethylamine, tetramethylethylenediamine, hexamethylenediamine, spermidine, spermine, amantadine, aniline, phenethylamine, toluidine, pyrrolidine, piperidine, piperazine, morpholine, imidazole, pyridine, pyridazine, pyrimidine, pyrazine, 4-dimethylaminopyridine, etc. Examples of the quaternary ammonium compound include amidine compounds (including imidazole compounds).

[0041] The liquid component may contain the acid component and the basic component in a free state, respectively, or in the form of a salt. The liquid component may contain an organic salt. Examples of the organic salt include those in which at least one of the acid component and the basic component is organic. Examples of the organic salt that may be used include trimethylamine maleate, triethylamine phthalate, ethyldimethylamine phthalate, mono-1,2,3,4-tetramethylimidazolinium phthalate, mono-1,3-dimethyl-2-ethylimidazolinium phthalate, and triethylamine borodisalicylate.

[0042] The pH of the liquid component is preferably 4 or less, and may be 3.8 or less, or 3.6 or less. By setting the pH of the electrolytic solution within such a range, the deterioration of the conductive polymer component is likely to be suppressed. The pH is preferably 1.0 or more.

[0043] The concentration of the solute in the liquid component is, for example, 0.1% by mass or more, preferably 0.5% by mass or more. When the concentration of the solute is in such a range, by combining with the sugar alcohol component and the polyalkylene glycol component, the solute can be dissociated with high dissociability in the liquid component, and high film restorability of the dielectric layer can be ensured. The concentration of the solute is preferably 25% by mass or less, more preferably 15% by mass or less. When the concentration of the solute is in such a range, dedoping of the dopant can be suppressed. These lower limit values and upper limit values can be arbitrarily combined.

[0044] (Others) The water content in the liquid component may be less than 1.5% by mass or 1% by mass or less, preferably less than 0.5% by mass, and may be 0.1% by mass or less or 0.01% by mass or less. Although the sugar alcohol component generally has high solubility in water, by combining with the polyalkylene glycol component, the water content in the liquid component can be reduced to at least easily dissolve the sugar alcohol component in the polyalkylene glycol component by heating. And, although the sugar alcohol component has high crystallinity, once it is dissolved in the polyalkylene glycol component, precipitation is suppressed. Note that the water content is the content in the liquid component of the electrolytic capacitor in the initial state.

[0045] The liquid component containing the sugar alcohol component tends to have a relatively high viscosity at 20°C, but by combining with the polyalkylene glycol component, the sugar alcohol component can be dissolved in the polyalkylene glycol component by heating. The viscosity of the liquid component at 20°C is, for example, 200 mPa·s or more, and may be 500 mPa·s or more. Even when the viscosity of the liquid component at 20°C is in such a range, the viscosity can be reduced by heating. Therefore, the liquid component can be easily impregnated into the conductive polymer of the capacitor element, it becomes easier to ensure high film restorability of the dielectric layer, and it becomes easier to orient the conductive polymer to ensure high conductivity.

[0046] In this specification, the viscosity of the liquid component can be measured using a vibrating viscometer. As the vibrating viscometer, for example, the vibrating viscometer VM-100A manufactured by CBC is used. (Capacitor element) The capacitor element includes at least an anode body having a dielectric layer on its surface and a conductive polymer covering a part of the dielectric layer.

[0047] (Anode body) The anode body can include valve action metal, an alloy containing valve action metal, and a compound containing valve action metal, etc. These materials can be used alone or in combination of two or more. As the valve action metal, for example, aluminum, tantalum, niobium, and titanium are preferably used. An anode body with a porous surface can be obtained, for example, by roughening the surface of a base material (such as a foil-shaped or plate-shaped base material) containing valve action metal by etching or the like. Also, the anode body may be a molded body of particles containing valve action metal or a sintered body thereof. Note that the sintered body has a porous structure.

[0048] (Dielectric layer) The dielectric layer is formed by anodizing the valve action metal on the surface of the anode body by a forming treatment or the like. The dielectric layer only needs to be formed so as to cover at least a part of the anode body. The dielectric layer is usually formed on the surface of the anode body. Since the dielectric layer is formed on the porous surface of the anode body, it is formed along the inner wall surface of the holes and depressions (pits) on the surface of the anode body.

[0049] The dielectric layer contains an oxide of the valve action metal. For example, when tantalum is used as the valve action metal, the dielectric layer contains Ta2O5, and when aluminum is used as the valve action metal, the dielectric layer contains Al2O3. Note that the dielectric layer is not limited to this, as long as it functions as a dielectric. When the surface of the anode body is porous, the dielectric layer is formed along the surface of the anode body (including the inner wall surface of the holes).

[0050] (Conductive polymer layer) The conductive polymer adheres so as to cover part of the dielectric layer to form a conductive polymer layer. The conductive polymer constitutes at least part of the cathode body in the electrolytic capacitor. The conductive layer polymer layer may further contain at least one of a dopant and an additive, if necessary.

[0051] Examples of the conductive polymer include polypyrrole, polythiophene, polyfuran, polyaniline, polyacetylene, polyphenylene, polyphenylene vinylene, polyacene, polythiophene vinylene, etc. These may be used alone, or in combination of two or more, or may be copolymers of two or more monomers.

[0052] In this specification, polypyrrole, polythiophene, polyfuran, polyaniline, etc. each mean a polymer having polypyrrole, polythiophene, polyfuran, polyaniline, etc. as a basic skeleton. Therefore, derivatives of polypyrrole, polythiophene, polyfuran, polyaniline, etc. may be included. For example, polythiophene includes poly(3,4-ethylenedioxythiophene), etc.

[0053] The dopant may be a polyanion. Specific examples of the polyanion include polyvinyl sulfonic acid, polystyrene sulfonic acid, polyallyl sulfonic acid, polyacrylic sulfonic acid, polymethacrylic sulfonic acid, poly(2-acrylamido-2-methylpropanesulfonic acid), polyisoprene sulfonic acid, polyacrylic acid, etc. These may be used alone, or in combination of two or more. Also, these may be polymers of single monomers, or copolymers of two or more monomers. Among them, polyanions derived from polystyrene sulfonic acid are preferred.

[0054] The conductive polymer layer can be formed, for example, by chemically polymerizing and / or electrolytically polymerizing a raw material monomer on the dielectric layer. Alternatively, it can be formed by bringing a solution in which a conductive polymer is dissolved or a dispersion in which a conductive polymer is dispersed into contact with the dielectric layer. The conductive polymer layer only needs to be formed so as to cover at least a part of the dielectric layer.

[0055] For the cathode body as well, a metal foil may be used in the same manner as the anode body. The type of metal is not particularly limited, but it is preferable to use a valve metal such as aluminum, tantalum, niobium or an alloy containing a valve metal. If necessary, the surface of the metal foil may be roughened. A formation film may be provided on the surface of the metal foil, or a film of a metal (dissimilar metal) or a non-metal different from the metal constituting the metal foil may be provided. Examples of the dissimilar metal or non-metal include a metal such as titanium and a non-metal such as carbon.

[0056] (Separator) When a metal foil is used for the cathode body, a separator may be disposed between the metal foil and the anode body. The separator is not particularly limited, and for example, a non-woven fabric containing fibers of cellulose, polyethylene terephthalate, vinylon, polyamide (for example, aliphatic polyamide, aromatic polyamide such as aramid) may be used.

[0057] (Others) The electrolytic capacitor may be of a wound type, or may be either a chip type or a multilayer type. The configuration of the capacitor element may be selected according to the type of the electrolytic capacitor. (Container) As the material of the container, for example, a metal such as aluminum, stainless steel, copper, iron, brass or an alloy thereof can be used. The shape of the container is not particularly limited as long as it can accommodate the capacitor element and the liquid component. (Sealing body) The sealing body is not particularly limited as long as it can seal the opening of the container. The sealing body usually contains an elastic polymer. The sealing body may further contain a crosslinking agent, additives, etc. that crosslink the elastic polymer.

[0058] As the elastic polymer, an insulating one is used. Examples of the elastic polymer include butyl rubber, isoprene rubber, silicone rubber, fluororubber, ethylene propylene rubber, chlorosulfonated polyethylene rubber (such as Hypalon (trademark) rubber), etc. The sealing body may contain one kind of elastic polymer or two or more kinds.

[0059] Although the elastic polymer has high sealing performance, its heat resistance is not sufficient. In a high-temperature environment, it oxidizes and deteriorates, becoming brittle, and the sealing function of the sealing body deteriorates. An electrolytic capacitor may be assumed to be used in a high-temperature environment, such as in or near the engine room of a vehicle (such as an automobile). In an electrolytic capacitor containing a liquid component, if the affinity of the liquid component for the elastic polymer is high, the elastic polymer is likely to swell due to the liquid component. The elastic polymer swollen by the liquid component is more likely to deteriorate in a high-temperature environment. According to the present disclosure, by using the above liquid component, the deterioration of the elastic polymer contained in the sealing body can be effectively suppressed, and an electrolytic capacitor with excellent heat resistance can be obtained.

[0060] The proportion of the elastic polymer in the sealing body is, for example, 10% by mass or more, and may be 20% by mass or more. When the proportion of the elastic polymer is in such a range, the sealing body is likely to deteriorate in a high-temperature environment. Even in such a case, by using the above liquid component, the deterioration of the elastic polymer can be suppressed, and high heat resistance of the electrolytic capacitor can be ensured. From the viewpoint of easily ensuring the strength of the sealing body, the proportion of the elastic polymer is preferably 50% by mass or less or 40% by mass or less. In addition, when the elastic polymer is crosslinked with a crosslinking agent, the proportion of the elastic polymer is the proportion of the elastic polymer containing the crosslinking agent.

[0061] The elastic polymer constituting the sealing body is usually crosslinked with a crosslinking agent. In particular, an electrolytic capacitor provided with a sealing body containing an elastic polymer crosslinked with at least one crosslinking agent selected from the group consisting of phenolic resins (such as alkylphenol resin oligomers) and peroxides (such as organic peroxides) is particularly suitable for use in applications that require particularly high heat resistance. Even when such a sealing body is used, if a conventional liquid component is used, deterioration of the sealing body may not be suppressed due to swelling of the liquid component in a high-temperature environment. According to the present disclosure, even when such a sealing body assumed to be used in a high-temperature environment is used because the above liquid component is used, deterioration of the sealing body is suppressed and high heat resistance can be ensured.

[0062] The additive may include, for example, at least one selected from the group consisting of a reinforcing agent (such as carbon such as carbon black), an antioxidant, an anti-aging agent, a crosslinking agent, a crosslinking accelerator, a dispersion aid, a modifier, a vulcanizing agent, a vulcanization aid, and a processing aid.

[0063] The electrolytic capacitor has high heat resistance and can guarantee use in a high-temperature environment. For example, the electrolytic capacitor can guarantee use for 2000 hours or more at a temperature of 120 ° C (or 150 ° C). Further, the electrolytic capacitor is also suitable for applications arranged in the engine room of a vehicle or in the vicinity thereof where high durability and heat resistance are required.

[0064] The present disclosure also includes an electrolytic capacitor module including a plurality of the above-described electrolytic capacitors. The electrolytic capacitor module may include a plurality of electrolytic capacitors connected in parallel. When a current of 20 A or more flows through an electrolytic capacitor module in which a plurality of conventional electrolytic capacitors are connected in parallel, the temperature of the electrolytic capacitor becomes a high temperature of 100° C. or more (sometimes 120° C. or more or 150° C. or more) due to the ESR of each electrolytic capacitor, and it becomes unusable. In some cases, a large current such as 50 A or more or 100 A or more may flow through the entire module. Since the electrolytic capacitor of the present disclosure has excellent heat resistance, a plurality of electrolytic capacitors are connected in parallel to form an electrolytic capacitor module, and even when a current of 20 A or more (or 50 A or more or 100 A or more) flows through the entire module, long-term use (specifically, 1000 hours or more, preferably 1500 hours or more, more preferably 2000 hours or more) can be guaranteed. The allowable current of such an entire electrolytic capacitor module may be 20 A or more, or may be 50 A or more or 100 A or more.

[0065] FIG. 1 is a schematic cross-sectional view of the electrolytic capacitor according to the present embodiment, and FIG. 2 is a schematic view of a part of the capacitor element related to the electrolytic capacitor developed.

[0066] The electrolytic capacitor includes, for example, a capacitor element 10, a bottomed case 101 that houses the capacitor element 10 and a liquid component (not shown), a sealing body 102 that closes the opening of the bottomed case 101, a seat plate 103 that covers the sealing body 102, lead wires 104A and 104B that are led out from the sealing body 102 and penetrate the seat plate 103, and lead tabs 105A and 105B that connect the lead wires and the electrodes of the capacitor element 10. The vicinity of the open end of the bottomed case 101 is inwardly tapered, and the open end is curled so as to be caulked to the sealing body 102.

[0067] The capacitor element 10 is, for example, a wound body as shown in FIG. 2. The wound body includes an anode body 11 connected to a lead tab 105A, a cathode body 12 connected to a lead tab 105B, and a separator 13. A conductive polymer layer (not shown) is formed on the anode body 11. And at least the conductive polymer layer of the capacitor element 10 is impregnated with a liquid component.

[0068] The anode body 11 and the cathode body 12 are wound with the separator 13 interposed therebetween. The outermost periphery of the wound body is fixed by a winding tape 14. Note that FIG. 2 shows a partially unfolded state before fixing the outermost periphery of the wound body.

[0069] The electrolytic capacitor only needs to have at least one capacitor element, and may have a plurality of capacitor elements. The number of capacitor elements included in the electrolytic capacitor may be determined according to the application.

[0070] [Manufacturing Method of Electrolytic Capacitor] The electrolytic capacitor is manufactured by a manufacturing method including at least a step of preparing the above liquid component, a conductive polymer impregnation step of impregnating a dielectric layer with a conductive polymer, and a liquid component impregnation step of impregnating the capacitor element with the liquid component after the conductive polymer impregnation step. The manufacturing method of the electrolytic capacitor may include a step of adjusting the viscosity of the liquid component prior to the liquid component impregnation step. The manufacturing method of the electrolytic capacitor may further include a step of preparing a capacitor element and a step of sealing the capacitor element.

[0071] An example of the manufacturing method of the electrolytic capacitor will be described below. (1) Step of preparing the capacitor element 10 (i) Step of preparing the anode body 11 and the cathode body 12 having a dielectric layer For the raw materials of the anode body 11 and the cathode body 12, a metal foil formed of a valve-acting metal is used. In the case of the anode body 11, the surface of the metal foil is roughened by an etching process or the like, and a plurality of irregularities are formed on the surface of the metal foil. Next, a dielectric layer is formed on the surface of the roughened metal foil by a forming process or the like. If necessary, the surface of the cathode body 12 may be roughened.

[0072] (ii) Preparation of the wound body The anode body 11 and the cathode body 12 are wound with a separator 13 interposed therebetween to prepare a wound body. A winding tape 14 is disposed on the outer surface of the cathode body 12 located on the outermost layer of the wound body to fix the end portion of the cathode body 12. If necessary, a further forming process is performed on the wound body.

[0073] (iii) Step of forming the capacitor element 10 The capacitor element 10 can be formed by impregnating the dielectric layer with a conductive polymer (conductive polymer impregnation step). For example, a liquid conductive polymer dispersion is impregnated into the dielectric layer to form a film of the conductive polymer covering at least a part of the dielectric layer. Thereby, the capacitor element 10 in which the conductive polymer is disposed between the anode body 11 and the cathode body 12 is obtained. The step of applying the polymer dispersion to the surface of the dielectric layer may be repeated two or more times.

[0074] The conductive polymer dispersion includes, for example, a conductive polymer and a liquid medium in which the conductive polymer is dispersed. Examples of the liquid medium include water, an organic liquid medium, or a mixture thereof. The conductive polymer dispersion may further contain at least one of a dopant and an additive, if necessary. When the conductive polymer dispersion contains a sugar alcohol component, it is difficult for the dispersion to penetrate into the dielectric layer and it is difficult to impregnate the dielectric layer with the conductive polymer. Therefore, it is preferable that the conductive polymer dispersion does not contain a sugar alcohol component.

[0075] (2) Step of preparing the liquid component The liquid component can be prepared by mixing the constituent components of the liquid component. The sugar alcohol component has low solubility in non-aqueous solvents, but by combining it with the polyalkylene glycol component, a liquid component in which the sugar alcohol component is uniformly dissolved can be prepared. Note that this step may be performed before the liquid component impregnation step, before or after the preparation of the capacitor element, or during the preparation of the capacitor element.

[0076] More specifically, this step may include a step of dissolving the sugar alcohol component in the polyalkylene glycol component. By heating the sugar alcohol component and the polyalkylene glycol component to a temperature higher than the melting points of these components and lower than or equal to the boiling point or decomposition temperature, the sugar alcohol component can be dissolved in the polyalkylene glycol component. When the liquid component contains other components (such as solutes, other non-aqueous solvents, etc.), other components may coexist at the stage of dissolving the sugar alcohol component. Once the sugar alcohol component is dissolved in the polyalkylene glycol component, it is difficult to precipitate even when cooled. Therefore, when the liquid component contains other components, after dissolving the sugar alcohol component in the polyalkylene glycol component by heating, it can be cooled and then other components can be mixed.

[0077] The heating temperature is, for example, 30°C or higher and 200°C or lower, and may be 50°C or higher and 100°C or lower.

[0078] (3) Step of adjusting the viscosity of the liquid component Prior to the impregnation step, the viscosity of the liquid component may be adjusted. The viscosity of the liquid component is adjusted, for example, by adjusting the temperature of the liquid component. More specifically, the viscosity may be adjusted by heating the liquid component. Note that this step may also be performed in the step of preparing the liquid component. More specifically, the liquid component may be prepared under heating, and when the viscosity becomes low, it may be impregnated into the capacitor element 10.

[0079] In this process, it is preferable that the viscosity of the liquid component to be impregnated is less than 200 mPa·s, and more preferably 100 mPa·s or less or 70 mPa·s or less. By combining the sugar alcohol component and the polyalkylene glycol component, the viscosity of the liquid component can be adjusted to such a range by heating. Thereby, the liquid component can be easily impregnated into the conductive polymer of the capacitor element, it becomes easier to ensure the high film restorability of the dielectric layer, and it becomes easier to ensure high conductivity by orienting the conductive polymer.

[0080] The temperature of the liquid component to be impregnated may be, for example, 10°C or higher and 120°C or lower, or may be 20°C or higher and 100°C or lower or 20°C or higher and 70°C or lower. By heating the liquid component, the temperature of the liquid component to be impregnated may be adjusted to a temperature of 50°C or higher and 120°C or lower, 50°C or higher and 100°C or lower, or 50°C or higher and 70°C or lower.

[0081] (4) Liquid component impregnation process In this process, the capacitor element 10 may be impregnated with the liquid component. Thereby, an electrolytic capacitor having a conductive polymer and a liquid component is obtained. The liquid component may be impregnated into the capacitor element 10, for example, by accommodating the capacitor element 10 and the liquid component in a container, or may be impregnated by immersing the capacitor element 10 in the liquid component, or may be impregnated by dropping the liquid component onto the capacitor element 10.

[0082] (5) Step of sealing the capacitor element The capacitor element 10 is housed in the bottomed case 101 such that the lead wires 104A and 104B are located on the opening side of the bottomed case 101. The bottomed case 101 also houses the liquid component. Next, if the opening of the bottomed case 101 is closed with a sealing body 102 through which each lead wire passes, the opening end is caulked to the sealing body 102 and curled, and the seat plate 103 is arranged on the curled portion, an electrolytic capacitor as shown in FIG. 1 is completed.

[0083] In the above embodiment, a wound-type electrolytic capacitor has been described. However, the scope of application of the present invention is not limited to the above, and it can also be applied to other electrolytic capacitors, for example, chip-type electrolytic capacitors using a sintered body of metal as the anode body, or laminated-type electrolytic capacitors using a metal plate as the anode body.

Examples

[0084] Hereinafter, the present invention will be specifically described based on examples and comparative examples, but the present invention is not limited to the following examples.

[0085] 《Fabrication of Electrolytic Capacitors E1 to E16 and C1 to C4》 A wound-type electrolytic capacitor (diameter 10 mm × L (length) 10 mm) with a rated voltage of 25 V and a rated capacitance of 330 μF was fabricated. The following describes the specific manufacturing method of the electrolytic capacitor.

[0086] (Preparation of Anode Body) The aluminum foil with a thickness of 100 μm was subjected to an etching treatment to roughen the surface of the aluminum foil. Then, a dielectric layer was formed on the surface of the aluminum foil by a chemical conversion treatment. The chemical conversion treatment was performed by immersing the aluminum foil in an ammonium adipate solution and applying a voltage of 180 V thereto. Then, the aluminum foil was cut to prepare the anode body.

[0087] (Preparation of Cathode Body) The aluminum foil with a thickness of 50 μm was subjected to an etching treatment to roughen the surface of the aluminum foil. Then, the aluminum foil was cut to prepare the cathode body.

[0088] (Fabrication of Wound Body) An anode lead tab and a cathode lead tab were connected to the anode body and the cathode body, respectively, and the anode body and the cathode body were wound around each other via a separator while incorporating the lead tabs. An anode lead wire and a cathode lead wire were respectively connected to the ends of each lead tab protruding from the wound body. The produced wound body was subjected to a formation treatment again, and a dielectric layer was formed on the cut end of the anode body. Next, the end of the outer surface of the wound body was fixed with a winding tape to produce a wound body.

[0089] (Preparation of Polymer Dispersion) 3,4-Ethylenedioxythiophene and polystyrene sulfonic acid (PSS, weight average molecular weight 100,000), which is a polymer dopant, were dissolved in ion-exchanged water to prepare a mixed solution. While stirring the mixed solution, iron(III) sulfate (oxidizing agent) dissolved in ion-exchanged water was added to carry out a polymerization reaction. After the reaction, the obtained reaction solution was dialyzed to remove unreacted monomers and excess oxidizing agent, and a polymer dispersion containing polyethylene dioxythiophene (PEDOT / PSS) doped with about 5% by mass of PSS was obtained.

[0090] (Formation of Solid Electrolyte Layer) In a reduced-pressure atmosphere (40 kPa), the wound body was immersed in the polymer dispersion contained in a predetermined container for 5 minutes, and then the wound body was pulled out from the polymer dispersion. Next, the wound body impregnated with the polymer dispersion was dried in a drying furnace at 150°C for 20 minutes to form a solid electrolyte layer composed of a conductive polymer layer covering at least a part of the dielectric layer. A capacitor element was formed in this way.

[0091] (Preparation of Liquid Component) The sugar alcohol component and the polyalkylene glycol component shown in Table 1 were mixed, and the mixture was heated to 95°C with stirring to dissolve the sugar alcohol component. Triethylamine phthalate was added as a solute to the resulting mixed solvent so that the concentration was 15% by mass, and they were mixed. The liquid component was prepared in this way.

[0092] For electrolytic capacitors C1 to C4, the non-aqueous solvents shown in Table 1 were used as the liquid component.

[0093] (Assembly of Electrolytic Capacitor) The liquid component was heated to 60 °C or higher to adjust the viscosity to less than 200 mPa·s. 200 mg of the liquid component with adjusted viscosity was accommodated in the case together with the capacitor element, and the capacitor element was impregnated with the liquid component over 5 minutes in a reduced-pressure atmosphere (40 kPa). The opening of the case was sealed using a sealing body to complete the electrolytic capacitor as shown in FIG. 1. Thereafter, an aging treatment was performed at 130 °C for 2 hours while applying the rated voltage. The viscosity of the liquid component was measured using a vibration viscometer VM-100A manufactured by CBC Co., Ltd.

[0094] As the sealing body, a disk-shaped elastic member containing butyl rubber, which was obtained by kneading a butyl polymer, a peroxide-based crosslinking agent, and an additive and molding using a mold, was used. As the additive, a reinforcing material (carbon black), a crosslinking accelerator, a dispersion aid (stearic acid), a hindered phenol-based antioxidant, and a modifier (silane coupling agent) were used. The usage amounts of the respective components were adjusted so that the content of butyl rubber, which is an elastic polymer component in the sealing body, would be the value in Table 1.

[0095] [Evaluation 1] (Measurement of ESR and Residual Amount of Liquid Component) Using an LCR meter, the ESR (initial ESR) at a frequency of 100 kHz / Ω of the obtained electrolytic capacitor was measured. Also, in order to evaluate the long-term reliability, it was held at 145 °C for 2000 hours while applying the rated voltage, and the increase rate (ΔESR) of the ESR was confirmed. ΔESR was expressed as the ratio (Z / Z0 × 100%) of the ESR (Z) of the electrolytic capacitor after holding at 145 °C to the initial value (Z0). ESR (Z) was measured in the same manner as in the case of the initial ESR using the electrolytic capacitor after holding at 145 °C.

[0096] After confirming the increase rate of the ESR, the electrolytic capacitor was disassembled, the liquid component was recovered, and the mass (g) was determined. The residual amount of the liquid component was expressed as the ratio (m / m0 × 100%) of the mass (m) of the liquid component after holding at 145 °C to the mass (m0) of the initial liquid component.

[0097] The evaluation results are shown in Table 1.

[0098]

Table 1

Industrial Applicability

[0099] The electrolytic capacitor of the present disclosure can be used as a hybrid type electrolytic capacitor. The electrolytic capacitor is particularly suitable for applications that require high heat resistance. However, the applications of the electrolytic capacitor are not limited to these.

Explanation of Signs

[0100] 100: Electrolytic capacitor 101: Bottomed case 102: Sealing body 103: Base plate 104A, 104B: Lead wires 105A, 105B: Lead tabs 10: Capacitor element 11: Anode body 12: Cathode body 13: Separator 14: Winding tape

Claims

1. A capacitor element and a liquid component, wherein the capacitor element includes an anode body having a dielectric layer on its surface and a conductive polymer covering a part of the dielectric layer, the liquid component includes a sugar alcohol component and a polyalkylene glycol component as solvents and a solute, the sugar alcohol component includes at least one selected from the group consisting of sugar alcohols having four or more hydroxy groups and their derivatives, the content of the sugar alcohol component in the liquid component is 8.5% by mass or more, the content (% by mass) of the polyalkylene glycol component in the liquid component is more than the content (% by mass) of the sugar alcohol component in the liquid component, an electrolytic capacitor, wherein the viscosity of the liquid component at 20°C is 200 mPa·s or more.

2. A method for manufacturing an electrolytic capacitor including a capacitor element including an anode body having a dielectric layer on its surface and a conductive polymer covering a part of the dielectric layer and a liquid component, comprising: a preparation step of preparing a liquid component including a sugar alcohol component and a polyalkylene glycol component as solvents and a solute; a conductive polymer impregnation step of impregnating the anode body having the dielectric layer with the conductive polymer; after the conductive polymer impregnation step, a liquid component impregnation step of impregnating the capacitor element with the liquid component, wherein the sugar alcohol component includes at least one selected from the group consisting of sugar alcohols having four or more hydroxy groups and their derivatives, the content of the sugar alcohol component in the liquid component is 8.5% by mass or more, the viscosity of the liquid component at 20°C is 200 mPa·s or more, the content (% by mass) of the polyalkylene glycol component in the liquid component is more than the content (% by mass) of the sugar alcohol component in the liquid component, and in the liquid component impregnation step, the liquid component is heated and impregnated into the capacitor element in a state where the viscosity of the liquid component is lower than the viscosity of the liquid component at 20°C.

3. A capacitor element and a liquid component, wherein the capacitor element includes an anode body having a dielectric layer on its surface and a conductive polymer covering a part of the dielectric layer, the liquid component includes a sugar alcohol component and a polyalkylene glycol component as solvents and a solute, The sugar alcohol component includes at least one selected from the group consisting of sugar alcohols having four or more hydroxy groups and derivatives thereof, the total of the content of the sugar alcohol component in the liquid component and the content of the polyalkylene glycol component in the liquid component is 68% by mass or more, the content (% by mass) of the polyalkylene glycol component in the liquid component is more than the content (% by mass) of the sugar alcohol component in the liquid component, an electrolytic capacitor, wherein the viscosity of the liquid component at 20°C is 200 mPa·s or more.

4. A method for manufacturing an electrolytic capacitor including a capacitor element including an anode body having a dielectric layer on a surface and a conductive polymer covering a part of the dielectric layer, and a liquid component, a preparation step of preparing a liquid component including a sugar alcohol component and a polyalkylene glycol component as solvents and a solute, a conductive polymer impregnation step of impregnating the anode body having the dielectric layer with the conductive polymer, after the conductive polymer impregnation step, a liquid component impregnation step of impregnating the capacitor element with the liquid component, the sugar alcohol component includes at least one selected from the group consisting of sugar alcohols having four or more hydroxy groups and derivatives thereof, the total of the content of the sugar alcohol component in the liquid component and the content of the polyalkylene glycol component in the liquid component is 68% by mass or more, the content (% by mass) of the polyalkylene glycol component in the liquid component is more than the content (% by mass) of the sugar alcohol component in the liquid component, the viscosity of the liquid component at 20°C is 200 mPa·s or more, In the liquid component impregnation step, the liquid component is heated and impregnated into the capacitor element in a state where the viscosity of the liquid component is lower than the viscosity of the liquid component at 20°C. A method for manufacturing an electrolytic capacitor.

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