Electrolytic capacitor and method for producing electrolytic capacitor

Abstract

Provided is a capacitor element comprising: an anode foil having a dielectric layer; a cathode foil; a separator interposed between the anode foil and the cathode foil; and an electrolyte interposed between the anode foil and the cathode foil and in contact with the separator. The electrolyte comprises an electroconductive component and a tacky component. The electroconductive component comprises an electroconductive polymer and a dopant. The anode foil and the separator are at least partly connected to each other by the electrolyte, the cathode foil and the separator are at least partly connected to each other by the electrolyte. The peel strength between the cathode foil and the separator is 3.0 N / mm or greater.

Description

Electrolytic capacitor and method for manufacturing the same

[0001] The present disclosure relates to electrolytic capacitors and methods for manufacturing electrolytic capacitors.

[0002] Known electrolytic capacitors include a wound assembly of an anode foil, a separator, and a cathode foil. One example of such an electrolytic capacitor includes a conductive polymer layer disposed in the wound assembly. The conductive polymer layer is formed, for example, by impregnating the wound assembly with a dispersion liquid containing a conductive polymer.

[0003] Patent Document 1 proposes a capacitor that includes "a processing element, the processing element including: an anode including a dielectric on a surface thereof and an anode conductive polymer layer on a surface thereof; a cathode including a cathode conductive polymer layer; a conductive separator between the anode and the cathode; an anode lead in electrical contact with the anode; and a cathode lead in electrical contact with the cathode."

[0004] Patent Document 2 proposes a "method for forming a solid electrolytic capacitor, comprising: preparing an anodized anode; and forming a conductive polymer layer on the anodized anode, wherein the conductive polymer layer comprises first particles comprising a conductive polymer and a polyanion; and second particles comprising the conductive polymer and the polyanion, the first particles having an average particle size of at least 1 micron to 10 microns, and the second particles having an average particle size of at least 1 nm to 600 nm." The conductive polymer layer may comprise an inner polymer layer and an outer polymer layer. The inner polymer layer is formed from a mixture containing nanoparticles of a conductive polymer and a polyanion in a solvent. The mixture may include at least one compound selected from the group consisting of a surfactant and an adhesion promoter.

[0005] Special table 2019-516241 publication Special table 2020-537350 publication

[0006] A first aspect of the present disclosure relates to a capacitor element. 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, and an electrolyte interposed between the anode foil and the cathode foil and in contact with the separator. The electrolyte includes a conductive component and an adhesive component. The conductive component includes a conductive polymer and a dopant. At least a portion of the space between the anode foil and the separator and at least a portion of the space between the cathode foil and the separator are connected by the electrolyte, and the peel strength between the cathode foil and the separator is 3.0 N / mm or more.

[0007] A second aspect of the present disclosure relates to an electrolytic capacitor, the electrolytic capacitor including the capacitor element according to the first aspect and a liquid component contained in voids within the capacitor element.

[0008] A third aspect of the present disclosure relates to a method for manufacturing an electrolytic capacitor. The method includes the steps of: (a) preparing an anode foil having a dielectric layer, a cathode foil, and a separator; (b) applying a coating liquid containing a conductive component and a liquid medium to at least one surface selected from the surface of the dielectric layer and the surface of the cathode foil and into voids in the separator; (c) removing at least a portion of the liquid medium from the coating liquid to deposit the conductive component on the at least one surface and into voids in the separator; (d) forming a capacitor element containing the conductive component by disposing the separator between the anode foil and the cathode foil; and (e) impregnating the capacitor element with a solution containing an adhesive component to form an electrolyte containing the conductive component and the adhesive component, thereby connecting at least a portion between the anode foil and the separator and at least a portion between the cathode foil and the separator with the electrolyte. The conductive component includes a conductive polymer and a dopant. The peel strength between the cathode foil and the separator is 3.0 N / mm or more.

[0009] A fourth aspect of the present disclosure relates to a method for manufacturing an electrolytic capacitor. The method includes the steps of: (a) preparing an anode foil having a dielectric layer, a cathode foil, and a separator; (b) applying a coating liquid containing a conductive component, an adhesive component, and a liquid medium to at least one surface selected from the surface of the dielectric layer and the surface of the cathode foil and into voids in the separator; (c) removing at least a portion of the liquid medium from the coating liquid to form an electrolyte containing the conductive component and the adhesive component on the at least one surface and in voids in the separator; and (d) forming a capacitor element containing the electrolyte by disposing the separator between the anode foil and the cathode foil, thereby connecting at least a portion between the anode foil and the separator and at least a portion between the cathode foil and the separator with the electrolyte. The conductive component includes a conductive polymer and a dopant. The peel strength between the cathode foil and the separator is 3.0 N / mm or greater.

[0010] According to the present disclosure, an electrolytic capacitor having a small rate of increase in equivalent series resistance (ESR) after heating at high temperatures can be obtained.

[0011] 1 is a diagram illustrating the configuration of an example of a peel strength measuring device; FIG. 2 is a side view schematically illustrating an electrolytic capacitor according to an embodiment of the present disclosure; FIG. 3 is an exploded perspective view schematically illustrating a capacitor element according to an embodiment of the present disclosure; and FIG. 4 is a diagram illustrating the relationship between peel strength and post-RF ESR relative value.

[0012] The problems in the prior art will be briefly described below.

[0013] In Patent Document 1, a capacitor is assembled using an anode on which a conductive polymer layer is formed. In this case, there is an interface between the anode and the cathode, where the conductive polymer layer and the electrode foil are not bonded to each other, or an interface between the conductive polymer layers themselves. Such an interface has a high resistance, which significantly increases the ESR of the electrolytic capacitor.

[0014] Patent Document 2 attempts to bond the interface between the conductive polymer layer and the electrode foil using a surfactant or an adhesion promoter, but such an interface is prone to peeling due to the action of the electrolyte or heat, causing deterioration due to heat such as reflow.

[0015] Furthermore, because the dispersion containing the conductive polymer has a high viscosity, even if the dispersion is impregnated into the wound body, a sufficient conductive polymer layer may not be formed inside the wound body. Insufficient formation of the conductive polymer layer can cause a decrease in initial capacity, an increase in ESR, a decrease in reliability, etc.

[0016] Hereinafter, embodiments according to the present invention will be described using examples, but the present invention 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 other materials may be applied as long as the invention according to the present disclosure can be implemented. In this specification, the expression "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 of numerical values ​​related to specific physical properties or conditions are exemplified, 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.

[0017] [Electrolytic Capacitor] A capacitor element according to a first aspect of the present disclosure includes an anode foil having a dielectric layer, a cathode foil, a separator, and an electrolyte. The separator is interposed between the anode foil and the cathode foil. The electrolyte is interposed between the anode foil and the cathode foil and is in contact with the separator. The electrolyte preferably contacts the anode foil, the cathode foil, and the separator over a sufficiently large contact area. This allows the electrolyte to form a sufficient conductive path between the anode foil and the cathode foil, reducing the ESR of the electrolytic capacitor and improving its reliability. The electrolytic capacitor may further include a liquid component contained in voids within the capacitor element.

[0018] In the manufacturing process, the electrolyte is preferably formed on at least one surface selected from the surface of the dielectric layer and the surface of the cathode foil, and is also preferably formed within the voids of the separator (i.e., the inner walls of the separator's constituent material surrounding the voids of the separator). This facilitates the formation of a strong conductive path via the electrolyte between the anode foil and the cathode foil. In the manufacturing process, the electrolyte is preferably formed at least on the surface of the dielectric layer of the anode foil and within the voids of the separator, and is more preferably formed on the surface of the cathode foil.

[0019] The electrolyte includes a conductive component and an adhesive component. The conductive component includes a conductive polymer and a dopant. The dopant is doped into the conductive polymer. At least a portion of the interface between the anode foil and the separator (hereinafter also referred to as the "anode foil / separator interface") and at least a portion of the interface between the cathode foil and the separator (hereinafter also referred to as the "cathode foil / separator interface") are connected by the electrolyte.

[0020] Here, the concept of connection includes adhesion. The adhesion phenomenon is exerted by the adhesive force of the electrolyte. The peel strength between the cathode foil and the separator can be used as an indicator of adhesive strength. By controlling the peel strength between the cathode foil and the separator to a predetermined value or higher, the rate of increase in ESR after heating at high temperatures can be significantly reduced. Specifically, the peel strength between the cathode foil and the separator is set to 3.0 N / mm or higher.

[0021] The peel strength (hereinafter also referred to as "peel strength CS") between the cathode foil and separator in a capacitor element is measured at any time after the anode foil / separator interface and the cathode foil / separator interface are connected by an electrolyte. In other words, it is sufficient that the peel strength CS reaches 3.0 N / mm or more at some point after the capacitor element is assembled. If a sufficiently large peel strength CS of 3.0 N / mm or more is achieved at some point, it is believed that the required sufficient level of peel strength CS can be maintained even if the peel strength CS subsequently fluctuates. Therefore, a sufficient conductive path formed by the electrolyte between the anode foil and the cathode foil is maintained, improving the reliability of the electrolytic capacitor.

[0022] The electrolyte layer is formed, for example, by forming a capacitor element containing a conductive component and then immersing the capacitor element in a solution containing an adhesive component. In this case, in order to sufficiently connect (or bond) the anode foil / separator interface and the cathode foil / separator interface with the electrolyte layer, the electrolyte layer is left to stand at 15 to 35°C for 12 hours or more after formation, and then the peel strength CS is measured.

[0023] The electrolyte layer is formed, for example, by applying a coating liquid containing a conductive component, an adhesive component, and a liquid medium to at least one surface selected from the surface of the dielectric layer and the surface of the cathode foil and into the voids of the separator, and then removing at least a portion of the liquid medium from the coating liquid. A separator is then placed between the anode foil and the cathode foil to form a capacitor element containing an electrolyte. In this case, the formed capacitor element is allowed to stand at 15 to 35°C for at least 12 hours before measuring the peel strength (CS).

[0024] The peel strength CS may be measured using a capacitor element removed from a completed electrolytic capacitor. When the electrolytic capacitor contains a liquid component and the capacitor element is impregnated with the liquid component, the peel strength CS may be measured using a capacitor element in a state where the liquid component is impregnated. Alternatively, the peel strength CS may be measured using a capacitor element from which at least a portion of the liquid component has been removed. Alternatively, the peel strength CS may be measured using a capacitor element in a dry state from which most of the liquid component (e.g., 90% by mass or more) has been removed. If the peel strength CS is 3.0 N / mm or more in either state, it can be said that a sufficient conductive path is formed between the anode foil and the cathode foil via the electrolyte.

[0025] A capacitor element is formed by winding an anode foil, a cathode foil, and a separator, with the separator disposed between the anode foil and the cathode foil. Hereinafter, such a capacitor element is also referred to as a wound body.

[0026] A capacitor element may be formed by stacking flat anode foils, flat cathode foils, and flat separators in one direction. Hereinafter, such a capacitor element is also referred to as a stack. For example, a stack may be formed by stacking multiple anode foils, multiple cathode foils, and multiple separators in one direction. In a typical example of a stack, the anode foils and cathode foils are alternately arranged, and separators are arranged between the anode foils and cathode foils.

[0027] <Method for measuring peel strength> (For wound body) The anode foil, together with the separator inside it, is peeled from the cathode foil located further inside the separator from the outer periphery of the wound body. As a result, a wound body sample is obtained in which the anode foil remains connected (adhered) to the separator on the outer periphery and the cathode foil has been peeled from the separator on the inner side (i.e., the wound body is partially unwound on the outer periphery).

[0028] If the outermost periphery of the wound body is an anode foil, the anode foil or the surface of a separator on its outer side will be disposed on the outer peripheral surface of the peeled anode foil. If the outermost periphery of the wound body is a cathode foil, the outer peripheral surface of the peeled anode foil will be disposed on the outer peripheral surface of the cathode foil or the surface of a separator on its outer side. Usually, the outermost periphery of the wound body is an anode foil, and in that case, a sample is obtained in which both of the pair of separators are connected (bonded) to the peeled anode foil.

[0029] Next, the surface of the sample facing the outer peripheral surface of the peeled anode foil is fixed to a predetermined feed sheet of the measuring device. Meanwhile, a predetermined drive device is used to pull the cathode foil peeled from the separator in a direction that forms an angle of 170 to 180° (preferably 175°) with the anode foil fixed to the feed sheet, continuously (for example, 60 seconds) at a constant speed (preferably 160 mm / min) to peel the cathode foil from the separator. The average tension (sampling interval: 0.01 seconds) at this time is measured as the peel strength.

[0030] FIG. 1 shows the configuration of an example of a peel strength measuring device. The measuring device is preferably designed to perform a test in accordance with JIS C0806-3:2014. Measuring device 20 includes feed sheet 21, feed rollers 22, and a recovery device 23. A surface of feed sheet 21 facing the outer periphery of peeled anode foil 11 is fixed by a fixture 24. Feed sheet 21 is fed in a first direction by feed rollers 22. Recovery device 23 recovers peeled cathode foil 12 while pulling it in a second direction opposite to the first direction. Recovery device 23 includes, for example, a take-up roller for winding up cathode foil 12. The feed speed of anode foil 11 by feed rollers 22 and the take-up speed of cathode foil 12 by recovery device 23 are controlled to prevent the position of capacitor element 10 from moving during measurement. As a measuring device having the above-mentioned configuration, for example, an embossed tape high speed peel strength tester (for example, "PTS-5000K") manufactured by EPI Co., Ltd. can be used.

[0031] (In the case of a laminate) A unit having three layers, i.e., an anode foil, a separator, and a cathode foil, is removed from the laminate. Separators may be attached (glued) to both sides of the anode foil and / or cathode foil of the unit. Next, a sample is obtained by peeling a portion of the cathode foil from the separator disposed between the anode foil and the cathode foil.

[0032] Next, a 180° peel test of the sample is performed in accordance with JIS K6854-2:1999. Specifically, the anode foil of the sample is fixed to a predetermined horizontal table of the measuring device using double-sided tape or the like. Meanwhile, the end of the cathode foil peeled from the separator is fixed to a horizontally movable jig. Then, the jig is driven to pull the cathode foil in a direction forming an angle of 180° with the anode foil, continuously peeling the cathode foil from the separator at a constant speed (preferably 160 mm / min). The tension at this time is measured as the peel strength. As the measuring device, for example, a digital force gauge (e.g., "FGP-1") manufactured by Nidec-Shimpo Corporation can be used.

[0033] The adhesive component constituting the electrolyte is not particularly limited, but may be, for example, at least one selected from the group consisting of sugar, sugar alcohol, epoxy resin, and polyvinyl alcohol. These are not only suitable as adhesive components, but also hardly reduce the performance of the electrolytic capacitor, do not affect the performance of the electrolytic capacitor, or may even improve the performance of the electrolytic capacitor.

[0034] Examples of sugars and sugar alcohols include mannitol, sorbitol, xylitol, pentaerythritol, trimethylolpropane, and derivatives thereof.

[0035] Examples of epoxy resins that can be used include biphenyl type epoxy resins, bisphenol A type epoxy resins, bisphenol F type epoxy resins, bisphenol AD ​​type epoxy resins, naphthalene type epoxy resins, glycidylamine type epoxy resins, phenol novolac type epoxy resins, phenolphthalein type epoxy resins, polyglycol-modified epoxy resins, polyolefin-modified bisphenol A type epoxy resins, alicyclic epoxy resins, dicyclopentadiene type epoxy resins, and polyether type epoxy resins.

[0036] Among sugars and sugar alcohols, at least one selected from the group consisting of xylitol and xylitol derivatives (hereinafter collectively referred to as "xylitol compounds") is particularly preferred. Xylitol compounds have a low melting point among sugar alcohols and excellent solubility in solvents. Even when used in large amounts, xylitol compounds are unlikely to precipitate during the manufacturing process or in the finished electrolytic capacitor.

[0037] Xylitol derivatives may be compounds in which some of the hydroxyl groups of xylitol are esterified, compounds in which some of the hydroxyl groups of xylitol are etherified, or compounds in which some of the hydroxyl groups of xylitol are anionized to form salts. However, the chemical structure of xylitol derivatives is not limited to these. The molar mass of the xylitol derivative may be in the range of 0.9 to 2 times the molar mass of xylitol (152.15 g / mol). The chemical formula of the xylitol derivative is the same as the chemical formula of xylitol (C ５ H ７ (OH) ５ ) can be used as a base, for example, C ５ H ７ (OH) ５-ａ X ａ (X may be an atom or group other than an OH group, and 1≦a≦4). X may be a halogen atom, an OM group (M is an alkali metal atom), OR (R is a hydrocarbon group having 5 or less carbon atoms, and at least one hydrogen atom of the hydrocarbon group may be substituted with a hydrophilic group such as a hydroxyl group or a carboxyl group, a halogen atom, or the like). It is preferable that X satisfies 1≦a≦3 or 1≦a≦2.

[0038] When the adhesive component is at least one first component selected from the group consisting of sugars and sugar alcohols, the mass content of the adhesive component (first component) in the total mass of the solid components of the electrolyte may be 30 mass% or more, 50 mass% or more, 30 mass% or more to 98 mass% or less, or 50 mass% or more to 93 mass% or less.

[0039] The solid component refers to a component that is solid at 35° C. or below. The solid component includes sugar, sugar alcohol, resin component, conductive component, etc. The same applies hereinafter.

[0040] Preferably, the mass content of the first component in the total mass of the solid components of the electrolyte is greater than the mass content of each of all other components in the electrolyte.

[0041] When the adhesive component is at least one selected from the group consisting of epoxy resins and polyvinyl alcohols, the mass content of the adhesive component in the total mass of the solid components of the electrolyte may be 50 mass% or less, 33 mass% or less, 30 mass% or less, or 1 mass% or more and 30 mass% or less.

[0042] When at least one first component selected from the group consisting of sugars and sugar alcohols and at least one second component selected from the group consisting of epoxy resins and polyvinyl alcohols are used as adhesive components, the total mass content of the adhesive components in the total mass of the solid components of the electrolyte may be 30% by mass or more, 50% by mass or more, 50% by mass to 98% by mass or less, or 50% by mass to 93% by mass or less. However, it is preferable that the mass content of the second component in the total mass of the solid components of the electrolyte is 50% by mass or less or 33% by mass or less, with the remainder being the first component. It is also desirable that the content of the first component be greater than the content of the second component.

[0043] When the adhesive component is at least one first component selected from the group consisting of sugars and sugar alcohols, the ratio (Ma / Mp) of the mass Ma of the adhesive component (first component) to the mass Mp of the conductive component is preferably at least 1, more preferably at least 2, and even more preferably at least 7. The ratio (Ma / Mp) is preferably at most 45, more preferably at most 20, and even more preferably at most 15. When these conditions are satisfied, the contact area between the electrolyte and the anode foil, cathode foil, and separator increases, and a sufficient conductive path through the electrolyte is easily formed between the anode foil and the cathode foil.

[0044] When the adhesive component is at least one second component selected from the group consisting of epoxy resin and polyvinyl alcohol, the ratio (Ma / Mp) of the mass Ma of the adhesive component (second component) to the mass Mp of the conductive component is preferably 0.01 or more and 10 or less, and may be 0.01 or more and 5 or less.

[0045] The larger the ratio (Ma / Mp), the larger the amount of adhesive component contained in the electrolyte. Except when the content of the adhesive component in the total mass of the solid components of the electrolyte is excessively high, the larger the ratio (Ma / Mp), the more likely it is that the contact area between the electrolyte and the anode foil, the cathode foil, and the separator will increase, and the more likely it is that a sufficient conductive path will be formed between the anode foil and the cathode foil via the conductive polymer layer.

[0046] <Method of determining the ratio (Ma / Mp)> The ratio (Ma / Mp) of the mass Ma of the adhesive component to the mass Mp of the conductive component can be determined, for example, by the following method. In the following, an example will be described in which the adhesive component is a water-soluble component.

[0047] (When the electrolytic capacitor does not contain liquid components) First, the cathode foil is separated from the capacitor element. The cathode foil has an electrolyte attached to it. Next, the water-soluble components are removed from the cathode foil with the electrolyte attached. Water-soluble components include sugars, sugar alcohols, and polyvinyl alcohol. Because the conductive components have different solubility in water than the water-soluble components, the conductive polymer and dopant can be separated from the other components using water.

[0048] For example, when a cathode foil is immersed in excess ion-exchanged water, the water-soluble components are thoroughly removed, and the foil is then dried, the dried cathode foil does not contain any water-soluble components. Therefore, the mass of the water-soluble components can be measured from the dry mass of the cathode foil before and after the removal of the water-soluble components.

[0049] The mass content of each component contained in the water-soluble component can be measured by various analytical methods such as gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS).

[0050] Furthermore, the cathode foil from which the water-soluble components have been removed can be subjected to thermal analysis using, for example, a differential scanning calorimeter, thereby measuring the mass content of the conductive components contained in the sample.

[0051] Using the above measurement results, the ratio (Ma / Mp) in the electrolyte of an electrolytic capacitor that does not contain a liquid component can be determined.

[0052] (When the electrolytic capacitor contains a liquid component) First, the cathode foil is separated from the capacitor element, and the liquid component is separated from the cathode foil. For example, the cathode foil is immersed in an excess solvent that has an affinity for the liquid component, and after the solvent is thoroughly removed, the dried cathode foil contains no liquid component. Thus, a cathode foil can be obtained to which an electrolyte that does not contain a liquid component is attached.

[0053] Thereafter, in the same manner as when the electrolytic capacitor does not contain any liquid components, the water-soluble components are removed from the cathode foil to which the electrolyte is attached, and the sample is dried. The sample is then subjected to thermal analysis using, for example, a differential scanning calorimeter, whereby the mass content of the conductive components contained in the sample can be measured.

[0054] On the other hand, the mass content of each component contained in the separated liquid component and water-soluble component can be measured by various analytical methods such as gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS).

[0055] Alternatively, the liquid component alone can be separated and analyzed to determine the mass content of each component contained in the liquid component.

[0056] Furthermore, by separating the cathode foil from the capacitor element and then drying it without washing, the mass content of the solvent contained in the liquid component in the cathode foil can be determined. The mass content of the solute contained in the liquid component in the cathode foil can be determined from the mass content of the solvent and the separately determined mass contents of each component contained in the liquid component.

[0057] Using the above measurement results, the ratio (Ma / Mp) in the electrolyte of the electrolytic capacitor containing the liquid component can be determined.

[0058] (When the adhesive component is an epoxy resin) First, a solid component is separated from the electrolyte. The solid component contains a conductive component and an adhesive component. The solid component is immersed in a solvent that has a high affinity for the conductive component and ultrasonically dispersed, thereby separating the conductive component into the solvent. The solid component is then recovered, and the change in mass is measured, allowing the ratio (Ma / Mp) of the mass of the adhesive component Ma to the mass of the conductive component Mp to be determined.

[0059] (Conductive Component) The conductive polymer constituting the conductive component is not particularly limited, but includes, for example, polypyrrole, polythiophene, polyfuran, polyaniline, polyacetylene, and derivatives thereof. Such 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. The conductive polymer may also be a copolymer of two or more monomers. The weight-average molecular weight of the conductive polymer is not particularly limited and may be, for example, in the range of 1,000 to 100,000. A preferred example of the conductive polymer is poly(3,4-ethylenedioxythiophene) (PEDOT).

[0060] The dopant constituting the conductive component is not particularly limited, but may be a dopant containing an acidic group or a polymeric dopant containing an acidic group. Examples of the acidic group include a sulfonic acid group and a carboxyl group. 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.

[0061] From the viewpoint of suppressing dedoping from the conductive polymer, it is preferable to use a polymer 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, etc. 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).

[0062] 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.

[0063] The dopant may be polystyrene sulfonic acid, and the conductive polymer may be poly(3,4-ethylenedioxythiophene). That is, the conductive polymer doped with a dopant may be poly(3,4-ethylenedioxythiophene) doped with polystyrene sulfonic acid.

[0064] (Liquid Component) The electrolytic capacitor may further include a liquid component contained in the voids within the capacitor element. That is, the electrolytic capacitor according to the present disclosure may be a solid electrolyte electrolytic capacitor or a solid-liquid hybrid electrolytic capacitor. 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. The liquid component may fill at least a portion of the voids within the capacitor element.

[0065] Examples of the liquid component include a solvent and an electrolyte solution. A solvent having a solute dissolved therein can be used as the liquid component. The liquid component may include a first component of the adhesive component as the solute. The solute may further include at least one selected from the group consisting of an acid, a base, and an electrolyte salt. The total mass content of all solutes in the liquid component is preferably 70 mass% or less, and more preferably 50 mass% or less.

[0066] The solvent of the liquid component may be an organic solvent, an ionic liquid, or a protic solvent. Among these, the liquid component preferably contains a protic solvent. By using a protic solvent, it is possible to swell the conductive component contained in the electrolyte. The liquid component may contain a protic solvent and a solvent other than a protic solvent. One type of solvent may be used alone, or two or more types may be mixed and used.

[0067] Examples of the solvent include polyhydric alcohols such as ethylene glycol, propylene glycol, glycerin, and polyglycerin, cyclic sulfones such as sulfolane (SL), lactones such as γ-butyrolactone (γBL), 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.

[0068] A polymer solvent may be used as the solvent. Examples of polymer solvents include polyalkylene glycol, polyalkylene glycol derivatives, and compounds in which at least one hydroxyl group in a polyhydric alcohol is 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.

[0069] Among these, the solvent preferably contains at least one selected from the group consisting of ethylene glycol, diethylene glycol, triethylene glycol, ethylene glycol condensates having a molecular weight of 250 or less, glycerin, γ-butyrolactone, and sulfolane.

[0070] The acid component may be a polycarboxylic acid or a monocarboxylic acid. Examples of the polycarboxylic acid include aliphatic polycarboxylic acids (saturated polycarboxylic acids such as oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, 1,6-decanedicarboxylic acid, and 5,6-decanedicarboxylic acid; unsaturated polycarboxylic acids such as maleic acid, fumaric acid, and itanoic acid), aromatic polycarboxylic acids (phthalic acid, isophthalic acid, terephthalic acid, trimellitic acid, and pyromellitic acid), and alicyclic polycarboxylic acids (cyclohexane-1,2-dicarboxylic acid and cyclohexene-1,2-dicarboxylic acid).

[0071] Examples of monocarboxylic acids 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).

[0072] Among these, maleic acid, phthalic acid, benzoic acid, pyromellitic acid, and resorcylic acid are thermally stable and are therefore preferably used.

[0073] An inorganic acid may be used as the acid component. Typical examples of inorganic acids include phosphoric acid, phosphorous acid, hypophosphorous acid, alkyl phosphate ester, boric acid, fluoroboric acid, tetrafluoroboric acid, hexafluorophosphoric acid, benzenesulfonic acid, and naphthalenesulfonic acid.

[0074] The acid component may be a complex compound of an organic acid and an inorganic acid, such as borodiglycolic acid, borodisoxalic acid, or borodisalicylic acid.

[0075] 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, or 1-methylbenzimidazole is preferred. By using these, a capacitor with excellent impedance performance can be obtained.

[0076] 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.

[0077] A tertiary amine may 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 be used as the base component.

[0078] 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. Examples of organic salts that may be used include trimethylamine maleate, triethylamine borodisalicylate, ethyldimethylamine phthalate, mono-1,2,3,4-tetramethylimidazolinium phthalate, and mono-1,3-dimethyl-2-ethylimidazolinium phthalate.

[0079] To prevent the dopant from being dedoped, 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).

[0080] Next, examples of components of the electrolytic capacitor according to the present disclosure will be further described, although the components of the electrolytic capacitor are not limited to the following examples.

[0081] (Anode Foil) Examples of anode foils include metal foils containing at least one valve metal such as titanium, tantalum, aluminum, and niobium. The anode foil 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.

[0082] A dielectric layer is formed on the surface of the anode foil. The dielectric layer may be formed by chemically treating the anode foil. In this case, the dielectric layer may contain an oxide of a valve metal (e.g., aluminum oxide). 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. In an electrolytic capacitor, a dielectric layer is preferably formed on the end surface of the anode foil. On the other hand, the end surface of the anode foil does not necessarily need to be coated with an electrolyte.

[0083] (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 subjected to a chemical conversion treatment as necessary. In an electrolytic capacitor, the end surface of the cathode foil may not be coated with electrolyte.

[0084] 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.

[0085] 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 above-mentioned 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, carbon black, etc.

[0086] (Separator) A porous sheet can be used for 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 μm 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.

[0087] (Exterior Body) The exterior body includes a case and / or a sealing resin. There is no limitation thereto, and known cases and sealing resins may be used. The sealing resin may include a thermosetting resin. Examples of thermosetting resins include epoxy resins, phenolic resins, silicone resins, melamine resins, urea resins, alkyd resins, polyurethanes, polyimides, unsaturated polyesters, etc. The sealing resin may include a filler, a curing agent, a polymerization initiator, and / or a catalyst, etc.

[0088] An example of an electrolytic capacitor according to the present disclosure will be specifically described below with reference to the drawings. The components described above can be applied to the components of the example described below. The components of the example described below can be modified based on the above description. The matters described below may also be applied to the above-described embodiment. In the example described below, components that are not essential for the electrolytic capacitor of the present disclosure may be omitted.

[0089] Fig. 2 is a cross-sectional view schematically illustrating an example of an electrolytic capacitor 100 according to this embodiment. Fig. 3 is a schematic view showing a portion of a capacitor element 10 included in the electrolytic capacitor 100 in an exploded view.

[0090] Electrolytic capacitor 100 includes capacitor element 10, bottomed case 101 that houses capacitor element 10, sealing member 102 that closes the opening of bottomed case 101, seat plate 103 that covers sealing member 102, lead wires 104A and 104B that extend from sealing member 102 and pass through seat plate 103, and lead tabs 105A and 105B that connect the lead wires to electrodes of capacitor element 10. The vicinity of the open end of bottomed case 101 is drawn inward, and the open end is curled so as to be crimped to sealing member 102.

[0091] Capacitor element 10 in this example is a wound body as shown in Fig. 3. The wound body includes anode foil 11 connected to lead tab 105A, cathode foil 12 connected to lead tab 105B, and separator 13. Capacitor element 10 (wound body) contains an electrolyte.

[0092] The anode foil 11 and the cathode foil 12 are wound with a separator 13 interposed therebetween. The outermost periphery of the wound body is fixed with a stop tape 14. Note that Fig. 3 shows a partially unfolded state of the wound body before the outermost periphery is fixed.

[0093] The electrolytic capacitor may have at least one capacitor element, or may have a plurality of capacitor elements, and the number of capacitor elements included in the electrolytic capacitor may be determined depending on the application.

[0094] The electrolytic capacitor according to the present disclosure can be manufactured by the manufacturing method (I) or the manufacturing method (II) described below. However, the electrolytic capacitor may also be manufactured by a method other than the manufacturing methods (I) and (II).

[0095] [Method (I) for Manufacturing Electrolytic Capacitor] A third aspect of the present disclosure relates to a method (I) for manufacturing an electrolytic capacitor. The method (I) for manufacturing an electrolytic capacitor includes, in this order: step (a) of preparing an anode foil having a dielectric layer, a cathode foil, and a separator; step (b) of applying a coating liquid containing a conductive component and a liquid medium to at least one surface selected from the surface of the dielectric layer and the surface of the cathode foil and to voids in the separator; step (c) of removing at least a portion of the liquid medium from the coating liquid to deposit the conductive component on at least one surface and in voids in the separator; step (d) of disposing the separator between the anode foil and the cathode foil to form a capacitor element containing the conductive component; and step (e) of impregnating the capacitor element with a solution containing an adhesive component to form an electrolyte containing the conductive component and the adhesive component, thereby connecting the anode foil / separator interface and the cathode foil / separator interface via the electrolyte. However, step (e) is controlled so that the peel strength (CS) between the cathode foil and the separator is 3.0 N / mm or more. The peel strength (CS) may be measured at any timing after step (e).

[0096] <Step (a)> The step of preparing an anode foil, a cathode foil, and a separator each having a dielectric layer is not particularly limited. The materials for the anode foil, the cathode foil, and the separator are also not particularly limited. The materials already described may be used for the anode foil, the cathode foil, and the separator.

[0097] <Step (b)> In step (b), the coating liquid may be applied to the surface of the dielectric layer and the separator, or the coating liquid may be applied to the surface of the cathode foil and the separator. Alternatively, the coating liquid may be applied to the surface of the dielectric layer, the surface of the cathode foil, and the separator. If necessary, the coating liquid is applied to the dielectric layers formed on both sides of the anode foil, and the coating liquid is applied to both sides of the cathode foil. A layer of a conductive component (conductive component layer) is formed at the location where the coating liquid is applied.

[0098] The coating method of the coating liquid is not limited, and may be a known method. For example, a method using a coater may be used, the coating liquid may be sprayed, or the object to be coated may be immersed in the coating liquid. Examples of the method using a coater include gravure coating and die coating.

[0099] In the gravure coating method, a coating liquid is applied to a transfer member such as a gravure roll, and excess coating liquid is removed from the transfer member. The coating liquid applied to the transfer member is then transferred to the anode foil, cathode foil, and separator, respectively, thereby forming a layer of coating liquid of uniform thickness on each of the anode foil, cathode foil, and separator. Methods for applying the coating liquid to the separator include methods for impregnating the separator with the coating liquid. The coating liquid applied to the separator penetrates into the separator, and the conductive polymer and dopant can be applied to the entire separator in the thickness direction.

[0100] The viscosity of the coating liquid may be, for example, 10 mPa·s or more (or 100 mPa·s or more) and 200 mPa·s or less. In this case, the coating liquid can be easily applied to the anode foil, the cathode foil, and the separator, and can easily be impregnated into the separator. The viscosity of the coating liquid is measured at room temperature (20°C) using a vibration viscometer (for example, VM-100A, manufactured by Sekonic Corporation).

[0101] In the conductive component, the dopant may be doped into the conductive polymer. The dopant may be an anion having a negative charge, and the conductive polymer may be a cation having a positive charge. The ionized dopant and the conductive polymer may interact with each other through Coulomb force. The conductive polymer doped with the dopant may be dispersed in the coating liquid in the form of particles.

[0102] The liquid medium preferably contains water. The liquid medium may contain an organic compound that does not boil at 100°C under 1 atmosphere (hereinafter also referred to as "organic compound (C)"). The liquid medium may contain one or more organic compounds (C). The organic compound (C) can be read as "at least one organic compound."

[0103] In this specification, unless otherwise specified, boiling point means the boiling point at 1 atmosphere. Examples of the organic compound (C) include organic compounds having a boiling point higher than 100°C. When the organic compound (C) has a boiling point, the boiling point may be 110°C or higher, 150°C or higher, or 200°C or higher, or 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., 150°C to 350°C).

[0104] In a preferred example of production method (I), the water content in the coating liquid is preferably 40% by mass or more (e.g., 50% by mass or more), and after the conductive component layer is formed, a solution containing an adhesive component or a liquid component (e.g., an electrolyte solution) can easily penetrate into the conductive component layer. When an organic compound (C) is used, the content of the organic compound (C) in the coating liquid may be 0% by mass or more and 10% by mass or less.

[0105] Water boils and evaporates at about 100°C at 1 atmosphere. On the other hand, the organic compound (C) is a compound that does not boil at 100°C at 1 atmosphere. Therefore, by heating the coating liquid at a temperature above 100°C at which the organic compound (C) does not boil or decompose, water can be removed from the coating liquid while the organic compound (C) remains. As a result, the organic compound (C) remains in the formed conductive component layer. In this case, a solution containing an adhesive component or a liquid component (e.g., an electrolyte solution) can easily penetrate the conductive component layer thereafter.

[0106] <Step (c)> In step (c), there is no limitation on the method for removing at least a portion of the liquid medium from the coating liquid. The liquid medium may be removed by heating and / or reducing pressure, and it is preferable to at least heat the coating liquid.

[0107] When heating is performed, it is preferable to remove a portion of the liquid medium 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 liquid medium. The heating temperature is preferably a temperature at which the organic compound (C) does not boil or decompose. When the organic compound (C) is a compound without a clear boiling point, it is preferable to heat at a temperature at which evaporation of the organic compound (C) is minimal and at which the organic compound (C) does not decompose. The heating temperature may be 100°C or higher, 120°C or higher, or 140°C or higher, and may be 200°C or lower, or 160°C or lower. The heating temperature may be in the range of 100°C to 200°C. The heating time is not particularly limited as long as it is a time that allows at least a portion of the liquid medium to be appropriately removed. An example heating time is in the range of 5 to 60 minutes.

[0108] When a conductive component is applied to one member, heating may be performed two or more times within a predetermined temperature range (for example, a temperature in the range of 100°C to 200°C). For example, when a conductive component is applied to dielectric layers formed on both sides of an anode foil, a coating liquid may be applied to one side and then heated, and then a coating liquid may be applied to the other side and then heated. A similar method can be applied when a conductive component is applied to both sides of a cathode foil.

[0109] <Step (d)> In step (d), a conductive component is applied to at least one of the anode foil and the cathode foil and the separator, and then the separator is disposed between the anode foil and the cathode foil, thereby forming a capacitor element containing the conductive component (step (d)).

[0110] <Step (e)> In step (e), the capacitor element is impregnated with a solution containing an adhesive component (hereinafter also referred to as "adhesive component solution"). This allows the conductive component to contain the adhesive component, thereby forming an electrolyte layer. The solvent of the adhesive component solution preferably contains at least water. 80% by mass or more, and even 90% by mass or more (preferably 100%) of the solvent of the adhesive component solution may be water. The solvent of the adhesive component solution may also contain an organic solvent. Examples of organic solvents that can be used include ethylene glycol, sulfolane, and γ-butyrolactone. The mass content of the adhesive component in the adhesive component solution is preferably 15% by mass to 60% by mass, and may be 10% by mass to 75% by mass.

[0111] There is no limitation on the method for impregnating the capacitor element with the adhesive component solution. For example, the capacitor element may be impregnated with the adhesive component by immersing at least a portion of the capacitor element in the adhesive component solution. The step of immersing at least a portion of the capacitor element in the adhesive component solution and the step of removing at least a portion of the solvent may be performed multiple times (for example, two or more times, or three or more times). The adhesive component solution may be heated to 40°C to 90°C. The step of removing at least a portion of the solvent may be performed by heating the capacitor element at, for example, 100°C or higher. The drying time may be, for example, five minutes or longer.

[0112] After forming the electrolyte layer in this manner, the capacitor element may be left to stand at 15 to 35°C for 12 hours or more to allow the anode foil / separator interface and the cathode foil / separator interface to be sufficiently connected (or bonded) by the electrolyte layer. The peel strength CS may be measured after the capacitor element has been left to stand.

[0113] After step (e), a step of impregnating the voids in the capacitor element with a liquid component may be further performed. In this case, a solid-liquid hybrid electrolytic capacitor can be obtained. The method for impregnating the voids in the capacitor element with the liquid component is not limited. For example, the capacitor element may be impregnated with the liquid component by immersing at least a portion of the capacitor element in the liquid component.

[0114] According to the manufacturing method (I), for example, in step (e), the step of impregnating at least a portion of the capacitor element with the adhesive component solution and the step of removing at least a portion of the solvent are performed one or more times (preferably two or more times or three or more times), thereby making it possible to control the peel strength between the cathode foil and the separator to be 3.0 N / mm or more.

[0115] A typical electrolytic capacitor includes a wound assembly of an anode foil, a separator, and a cathode foil. Such an electrolytic capacitor includes conductive components (conductive polymer and dopant) disposed within the wound assembly. The conductive components are disposed within the wound assembly by impregnating the wound assembly with a dispersion containing the conductive components.

[0116] However, because dispersions containing conductive components have high viscosity, even if the dispersion is impregnated into the wound body, it may not be possible to incorporate a sufficient amount of conductive component into the wound body. An insufficient amount of conductive component can result in a decrease in initial capacity, an increase in equivalent series resistance (ESR), a decrease in reliability, and the like. Furthermore, because the adhesive component is a solid, the viscosity of the adhesive component solution increases. If the adhesive component is added to the dispersion containing the conductive component, it becomes even more difficult to incorporate a sufficient amount of conductive component into the wound body.

[0117] On the other hand, the electrolytic capacitor manufacturing method (I) includes steps (b) and (c), in which a coating liquid is applied to at least one surface selected from the surface of the dielectric layer of the anode foil and the surface of the cathode foil, and the coating liquid is also applied to the voids of the separator. The coating liquid may be highly viscous due to the presence of a conductive component. However, when the coating liquid is applied to the surface of the dielectric layer or the surface of the cathode foil, for example, using a coater, a sufficient amount of conductive component can be deposited within the capacitor element. Similarly, the electrolytic capacitor manufacturing method (I) also includes steps (b) and (c), in which a coating liquid is applied to the surface of the separator, for example, using a coater, a sufficient amount of conductive component can be deposited within the voids of the separator (more precisely, the inner wall formed of the separator material surrounding the voids).

[0118] Furthermore, when a sugar alcohol such as a xylitol compound is used as the adhesive component in step (e) of the manufacturing method (I) of an electrolytic capacitor, the sugar alcohol has excellent solubility in solvents, allowing a sufficient amount of sugar alcohol to be contained within the conductive component. Sugar alcohols easily penetrate the conductive component. Xylitol compounds, in particular, easily penetrate the conductive component. Sugar alcohols or xylitol compounds easily penetrate the conductive components formed on each component, allowing electrolytes to adhere to each other. Therefore, a strong conductive path via the electrolyte can be formed between the anode foil and the cathode foil.

[0119] In production method (I), the conductive component layer can be formed as a combination of a first conductive component layer formed on the surface of the dielectric layer of the anode foil and / or the surface of the cathode foil, and a second conductive component layer formed in the voids of the separator.

[0120] The first conductive component layer and the second conductive component layer may contain the same conductive component or different conductive components. The first conductive component layer formed on the anode foil (on the dielectric layer) and the first conductive component layer and the second conductive component layer formed on the cathode foil may contain the same conductive component or different conductive components.

[0121] When a first conductive component layer is formed on the surface of an anode foil (or cathode foil), it is preferable that the first conductive component layer be formed on 80% or more (e.g., 90% or more) of the surface area on which the first conductive component layer is formed. The first conductive component layer is preferably formed on the entire surface of the electrode foil (anode foil, cathode foil) that contributes to the capacitance of the capacitor element. The area on which the second conductive component layer is formed on the separator is preferably 80% or more (e.g., 90% or more) of the separator's area, and may be formed on the entire separator. Here, the surface area of ​​the electrode foil (anode foil, cathode foil) refers to the area ignoring surface irregularities and can be calculated from the outline of the electrode foil. When the first conductive component layer is formed on both sides of the electrode foil, the surface area on which the first conductive component layer is formed is the sum of the areas of both sides.

[0122] The mass of the first conductive component layer per unit area is 0.01 mg / cm ２ or more, or 0.02 mg / cm ２ or more, and may be 0.5 mg / cm ２ or less than 0.3 mg / cm ２ The mass may be 0.1 mg / cm or less. ２ By doing so, the conductive component layer can be formed more uniformly. Note that when the first conductive component layer is formed on both sides of the electrode foil, the above mass per unit area is the mass of the layer formed on one side of the electrode foil.

[0123] The mass of the second conductive component layer per unit area is 0.02 mg / cm ２ or more, or 0.05 mg / cm ２ or more, and ２ or less than 1.0 mg / cm ２ The mass may be 0.3 mg / cm or less. ２ By doing so, the conductive component layer can be formed more uniformly.

[0124] The mass of the conductive component layer per unit area can be determined by the following method. First, five samples are prepared by cutting out a predetermined area from a member (electrode foil or separator) before the conductive component layer is formed, and the masses of the five samples are measured. Five samples are also prepared by cutting out a predetermined area from a member (electrode foil or separator) on which the conductive component layer has been formed, and the masses of the five samples are measured. The mass of the conductive component layer per unit area is determined using the predetermined area and the difference between the total mass of the five samples after the conductive component layer has been formed and the total mass of the five samples before the conductive component layer has been formed.

[0125] The above steps form a capacitor element containing an electrolyte. The capacitor element is then encapsulated in an outer casing, if necessary. In this manner, an electrolytic capacitor is manufactured. Note that manufacturing method (I) may include other steps as needed.

[0126] [Method (II) for Manufacturing Electrolytic Capacitor] A fourth aspect of the present disclosure relates to a method (II) for manufacturing an electrolytic capacitor. The method (II) for manufacturing an electrolytic capacitor includes, in order: (a) preparing an anode foil having a dielectric layer, a cathode foil, and a separator; (b) applying a coating liquid containing a conductive component, an adhesive component, and a liquid medium to at least one surface selected from the surface of the dielectric layer and the surface of the cathode foil and to voids in the separator; (c) forming an electrolyte containing the conductive component and the adhesive component in the at least one surface and voids in the separator by removing at least a portion of the liquid medium from the coating liquid; and (d) forming a capacitor element containing the electrolyte by disposing a separator between the anode foil and the cathode foil, thereby connecting the anode foil / separator interface and the cathode foil / separator interface with the electrolyte. Note that step (d) is controlled so that the peel strength (CS) between the cathode foil and the separator is 3.0 N / mm or greater. The peel strength (CS) may be measured at any time after step (d).

[0127] That is, manufacturing method (II) differs from manufacturing method (I) in that the adhesive component is contained in the coating liquid, and therefore the step of impregnating the capacitor element with the adhesive component solution (step (d) in manufacturing method (I)) does not need to be performed. Otherwise, the procedure of manufacturing method (II) is the same as manufacturing method (I). However, manufacturing method (II) may also perform step (d) of manufacturing method (I).

[0128] In step (b) of manufacturing method (II), a coating liquid is applied to at least one surface selected from the surface of the dielectric layer of the anode foil and the surface of the cathode foil, and the coating liquid is also applied into the voids of the separator. The coating liquid contains a conductive component and also an adhesive component, which can result in high viscosity. However, when the coating liquid is applied to the surface of the dielectric layer or the surface of the cathode foil, for example, using a coater, a sufficient amount of electrolyte layer can be formed within the capacitor element, and the adhesive component can be contained in the electrolyte layer at any mass content. Similarly, when the coating liquid is applied to the surface of the separator, for example, using a coater, a sufficient amount of electrolyte can be formed within the voids of the separator, and the adhesive component can be contained in the electrolyte at any mass content.

[0129] The peel strength CS may be measured after forming a capacitor element containing an electrolyte by disposing a separator between the anode foil and the cathode foil in step (d), and then leaving the capacitor element at rest at 15 to 35°C for 12 hours or more.

[0130] In the production method (II), if a step of impregnating the voids in the capacitor element with a liquid component is further carried out after the step (d), a solid-liquid hybrid electrolytic capacitor can be obtained.

[0131] As described above, in manufacturing methods (I) and (II), a conductive component layer can be formed by combining a first conductive component layer formed on the surface of the dielectric layer of the anode foil and / or the surface of the cathode foil with a second conductive component layer formed in the voids of the separator. According to manufacturing methods (I) and (II), a mixed region where a portion of the first conductive component layer and a portion of the second conductive component layer are mixed can be formed at the boundary between the first conductive component layer and the second conductive component layer. This is believed to be because the conductive component layer contains a sufficient amount of adhesive component, which penetrates the first and second conductive component layers and acts to fuse a portion of the first conductive component layer with a portion of the second conductive component layer. In other words, the first conductive component layer and the second conductive component layer can be bonded to each other. This forms a strong conductive path via the electrolyte between the anode foil and the cathode foil, reducing the ESR of the electrolytic capacitor and significantly improving its reliability.

[0132] (Adhesive component solution) Next, the adhesive component solution will be described in more detail. The adhesive component solution contains a liquid medium and an adhesive component. The liquid medium preferably contains water, and further contains an organic compound (C). If necessary, the adhesive component solution may contain other components. As the organic compound (C), an organic compound that is easily soluble in water can be preferably used. The organic compound (C) may be a compound that is miscible with water.

[0133] It is preferred that the majority of the adhesive component is a sugar and / or a sugar alcohol (e.g., a xylitol compound).It is preferred that 80% by mass or more (even 90% by mass or more) of the adhesive component contained in the adhesive component solution is a sugar and / or a sugar alcohol (e.g., a xylitol compound).

[0134] Examples of the organic compound (C) include compounds used as organic solvents. Examples of the organic compound (C) include polyhydric alcohols (excluding sugars and sugar alcohols) having two or more hydroxyl groups. Water in which the organic compound (C) is dissolved can be used as a dispersion medium for the conductive component. From one perspective, the coating liquid is a dispersion liquid in which particles of a conductive polymer doped with a dopant are dispersed, and the dispersion medium can be water in which the organic compound (C) and / or an adhesive component are dissolved.

[0135] Examples of the organic compound (C) include polyhydric alcohols (excluding sugars and sugar alcohols), sulfolane, γ-butyrolactone, boric acid esters, etc. The organic compound (C) may include at least one selected from the group consisting of polyhydric alcohols, sulfolane, γ-butyrolactone, and boric acid esters, or may be at least one of the above.

[0136] Examples of polyhydric alcohols include glycols, glycerins, etc. Examples of glycols include ethylene glycol, diethylene glycol, triethylene glycol, polyalkylene glycol (e.g., polyethylene glycol), polyoxyethylene polyoxypropylene glycol (ethylene oxide-propylene oxide copolymer), etc. Examples of glycerins include glycerin and polyglycerin, etc.

[0137] The organic compound (C) preferably contains at least one selected from the group consisting of ethylene glycol, diethylene glycol, triethylene glycol, ethylene glycol condensates having a molecular weight of 250 or less, glycerin, γ-butyrolactone, and sulfolane.

[0138] The total content of the adhesive component and the organic compound (C) in the adhesive component solution may be 1.0% by mass or more, 3.0% by mass or more, 5.0% by mass or more, or 10% by mass or more. This content may be 59.5% by mass or less, 45% by mass or less, 30% by mass or less, 25% by mass or less, 20% by mass or less, 15% by mass or less, or 10% by mass or less. This content may be in the range of 1 to 59.5% by mass, 3 to 59.5% by mass, or 5 to 59.5% by mass. Within any of these ranges, the upper limit may be 45%, 30%, 25%, 20%, 15%, or 10% by mass.

[0139] (Coating Liquid) Next, the coating liquid will be described in more detail. The coating liquid contains a conductive component and a liquid medium, and may contain an adhesive component. The liquid medium preferably contains water, and further contains an organic compound (C). If necessary, the coating liquid may contain other components. As the organic compound (C), an organic compound that is easily soluble in water can be preferably used. The organic compound (C) may be a compound that is miscible with water.

[0140] When the coating liquid contains an adhesive component, the majority of the adhesive component is preferably a sugar and / or a sugar alcohol (e.g., a xylitol compound), and it is preferable that 80% by mass or more (even 90% by mass or more) of the adhesive component contained in the coating liquid is a sugar and / or a sugar alcohol (e.g., a xylitol compound).

[0141] In order to suppress dedoping of the dopant from the conductive polymer, the pH of the coating liquid is preferably less than 7.0, and may be 6.0 or less or 5.0 or less. The pH of the coating liquid may be 1.0 or more, or 2.0 or more.

[0142] The conductive component (conductive polymer doped with a dopant) may be present in the coating liquid in the form of particles. In the volume-based particle size distribution of the conductive component particles, 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.

[0143] The mode of particle size of the conductive 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 content 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 component layer in the pores of the members (electrode foil and separator).

[0144] The water content in the coating liquid may be 40% by mass or more, 50% by mass or more, 70% by mass or more, 73% by mass or more, 78% by mass or more, 80% by mass or more, 88% by mass or more, 90% by mass or more, or 95% by mass or more. The water content may be 98% by mass or less, 95% by mass or less, 90% by mass or less, or 80% by mass or less. The water content may be in the range of 40 to 98% by mass or more, 50 to 98% by mass, 80 to 98% by mass, or 70 to 98% by mass. In any of these ranges, the upper limit may be 95% by mass, 90% by mass, or 80% by mass.

[0145] The content of the adhesive component and the organic compound (C) in the coating liquid may be 1.0% by mass or more, 3.0% by mass or more, 5.0% by mass or more, or 10% by mass or more. The content may be 59.5% by mass or less, 45% by mass or less, 30% by mass or less, 25% by mass or less, 20% by mass or less, 15% by mass or less, or 10% by mass or less. The content may be in the range of 1 to 59.5% by mass, 3 to 59.5% by mass, or 5 to 59.5% by mass. Within any of these ranges, the upper limit may be 45%, 30%, 25%, 20%, 15%, or 10% by mass.

[0146] The mass content of the conductive component in the coating liquid may be 0.5 mass% or more or 1.0 mass% or more, and may be 4.0 mass% or less, 3.0 mass% or less, or 2.0 mass% or less. The content may be in the range of 0.5 to 4.0 mass% or 1.0 to 4.0 mass%. Within either of these ranges, the upper limit may be 3.0 mass% or 2.0 mass%. In terms of excellent physical properties and stability over time of the coating liquid, and a good balance between the ESR and cost of the electrolytic capacitor, the content is preferably in the range of 1.0 to 3.0%.

[0147] There are no particular limitations on the mass of the dopant contained in the coating liquid, and it may be in the range of 0.1 to 5 times (for example, in the range of 0.5 to 3 times) the mass of the conductive polymer contained in the coating liquid.

[0148] The mass content of the adhesive component in the coating liquid is preferably 1 to 45 times, 1 to 15 times, 7 to 20 times, or 7 to 15 times the mass content of the conductive component in the coating liquid. Furthermore, in terms of excellent physical properties and stability over time of the coating liquid and a good balance between the ESR and cost of the electrolytic capacitor, the content is preferably in the range of 1.0 to 3.0%.

[0149] In the coating liquid, the ratio of water content:total content of adhesive component and organic compound (C):total content of conductive component may be (40 to 98):(1.0 to 59.5):(0.5 to 4.0), or may be (69.5 to 98):(1.0 to 30):(0.5 to 4.0).

[0150] The above-mentioned water content, total content of the adhesive component and the organic compound (C), and content of the conductive component can be combined arbitrarily as long as no contradiction occurs. One example of the coating liquid may satisfy one, two, three, or four conditions arbitrarily selected from the following conditions (1) to (6), or may satisfy all of the conditions.

[0151] (1) The water content is in the range of 50 to 98% by mass (e.g., 73 to 95% by mass), the total content of the adhesive component and the organic compound (C) is in the range of 3 to 30% by mass (e.g., 5 to 25% by mass), and the conductive component content is in the range of 0.5 to 4.0% by mass (e.g., 1.0 to 3.0% by mass). (2) The mass content of the adhesive component in the coating liquid is 1 to 45 times or 7 to 20 times the mass content of the conductive component in the coating liquid. (3) The organic compound (C) is a glycol (e.g., ethylene glycol, glycerin, or polyethylene glycol). (4) The electrolyte contains poly(3,4-ethylenedioxythiophene) and polystyrene sulfonic acid as conductive components. (5) The pH of the coating liquid is in the range of 1.0 to 6.0 (e.g., 2.0 to 5.0). (6) The conductive component is present in the coating liquid in the form of particles, and in the volume-based particle size distribution of the particles, the mode of particle size is in the range of 20 nm to 1000 nm (e.g., 20 nm to 200 nm or 20 nm to 100 nm). In the volume-based particle size distribution, the proportion (by volume) of particles with particle sizes in the range of 20 nm to 1000 nm (e.g., 20 nm to 200 nm or 20 nm to 100 nm) of the total particles may be 90% or more.

[0152] <<Supplementary Note>> The above description of the embodiment discloses the following techniques.

[0153] (Technology 1) A capacitor element comprising: an anode foil having a dielectric layer; a cathode foil; a separator interposed between the anode foil and the cathode foil; and an electrolyte interposed between the anode foil and the cathode foil and in contact with the separator, wherein the electrolyte includes a conductive component and an adhesive component, and the conductive component includes a conductive polymer and a dopant, at least a portion between the anode foil and the separator and at least a portion between the cathode foil and the separator are connected by the electrolyte, and a peel strength between the cathode foil and the separator is 3.0 N / mm or more.

[0154] (Technology 2) The capacitor element according to Technology 1, wherein the adhesive component is at least one selected from the group consisting of sugar, sugar alcohol, epoxy resin, and polyvinyl alcohol.

[0155] (Technology 3) The capacitor element according to Technology 1 or 2, wherein the adhesive component is at least one selected from the group consisting of sugars and sugar alcohols, and the mass content of the adhesive component in the total mass of solid components of the electrolyte is 50 mass% or more.

[0156] (Technology 4) The capacitor element according to Technology 1 or 2, wherein the adhesive component is at least one selected from the group consisting of epoxy resins and polyvinyl alcohols, and the mass content of the adhesive component in the total mass of solid components of the electrolyte is 50 mass% or less.

[0157] (Technology 5) The capacitor element according to any one of technologies 1 to 3, wherein the adhesive component is at least one selected from the group consisting of sugars and sugar alcohols, and the ratio (Ma / Mp) of the mass Ma of the adhesive component to the mass Mp of the conductive component is 7 or more and 15 or less.

[0158] (Technology 6) The capacitor element according to Technology 1, 2, or 4, wherein the adhesive component is at least one selected from the group consisting of epoxy resins and polyvinyl alcohols, and a ratio (Ma / Mp) of a mass Ma of the adhesive component to a mass Mp of the conductive component is 0.01 or more and 10 or less.

[0159] (Technology 7) An electrolytic capacitor comprising: the capacitor element according to any one of Technologies 1 to 6; and a liquid component contained in voids within the capacitor element.

[0160] (Technology 8) The electrolytic capacitor according to Technology 7, wherein the liquid component contains at least one selected from the group consisting of ethylene glycol, diethylene glycol, triethylene glycol, an ethylene glycol condensate having a molecular weight of 250 or less, glycerin, γ-butyrolactone, and sulfolane.

[0161] (Technology 9) The capacitor manufacturing method includes the steps of: (a) preparing an anode foil having a dielectric layer, a cathode foil, and a separator; (b) applying a coating liquid containing a conductive component and a liquid medium to at least one surface selected from a surface of the dielectric layer and a surface of the cathode foil, and into voids of the separator; (c) removing at least a part of the liquid medium from the coating liquid to adhere the conductive component to the at least one surface and into voids of the separator; (d) forming a capacitor element containing the conductive component by placing the separator between the anode foil and the cathode foil; and (e) impregnating the capacitor element with a solution containing an adhesive component to form an electrolyte containing the conductive component and the adhesive component, and connecting at least a part between the anode foil and the separator, and at least a part between the cathode foil and the separator by the electrolyte, in this order; the conductive component includes a conductive polymer and a dopant, a peel strength between the cathode foil and the separator of 3.0 N / mm or more.

[0162] (Technology 10) The method for producing an electrolytic capacitor according to Technology 9, further comprising, after the step (e), a step of impregnating voids in the capacitor element with a liquid component.

[0163] (Technology 11) A method for manufacturing an electrolytic capacitor, comprising the steps of: (a) preparing an anode foil having a dielectric layer, a cathode foil, and a separator; (b) applying a coating liquid containing a conductive component, an adhesive component, and a liquid medium to at least one surface selected from a surface of the dielectric layer and a surface of the cathode foil, and into voids of the separator; (c) forming an electrolyte containing the conductive component and the adhesive component on the at least one surface and in voids of the separator by removing at least a portion of the liquid medium from the coating liquid; and (d) forming a capacitor element containing the electrolyte by disposing the separator between the anode foil and the cathode foil, and connecting at least a portion between the anode foil and the separator, and at least a portion between the cathode foil and the separator, with the electrolyte, in this order; wherein the conductive component comprises a conductive polymer and a dopant; and wherein a peel strength between the cathode foil and the separator is 3.0 N / mm or more.

[0164] (Technology 12) The method for producing an electrolytic capacitor according to Technology 11, further comprising, after the step (d), a step of impregnating voids in the capacitor element with a liquid component.

[0165] [Examples] The present disclosure will be described in more detail below based on examples, but the present disclosure is not limited to these examples. In these examples, a plurality of electrolytic capacitors were produced and evaluated by the following method.

[0166] (Capacitor A1) An electrolytic capacitor was produced by the following method.

[0167] (a) 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 both sides was obtained.

[0168] 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.

[0169] 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.

[0170] (b) Preparation of Coating Liquid A dispersion (commercially available) in which particles (conductive component) of polyethylenedioxythiophene (PEDOT) doped with polystyrene sulfonic acid (PSS) were dispersed in water was prepared as a coating liquid.

[0171] (c) Formation of a Conductive Component Layer Using a gravure coater, the coating liquid was applied to one side of the anode foil (surface of the dielectric layer). A drying process was then performed to form a conductive component layer on one side of the anode foil (surface of the dielectric layer). The drying process was performed by heating the anode foil coated with the coating liquid at 125°C for 5 minutes. Next, a conductive component layer was formed on the other side of the anode foil (surface of the dielectric layer) in the same manner.

[0172] A conductive component layer was formed on both sides of the cathode foil in the same manner as that used for forming the conductive component layer on both sides of the anode foil. Also, a conductive component layer was formed on the separator by applying the coating liquid to the separator and then performing a drying process in the same manner as that used for forming the conductive component layer on both sides of the anode foil.

[0173] (d) Preparation of Capacitor Element The anode foil, cathode foil, and separator were each cut to a predetermined size. Anode lead tabs and cathode lead tabs were connected to the anode foil and cathode foil, respectively. Next, the anode foil and cathode foil were wound with the separator interposed therebetween. At this time, the ends of the outer surface of the wound body were fixed with winding tape. Anode lead wires and cathode lead wires were connected to the ends of each lead tab protruding from the wound body, respectively. The obtained wound body was again subjected to chemical conversion treatment, and a dielectric layer was formed on the end surface of the anode foil. In this way, a capacitor element was obtained.

[0174] (e) Impregnation with Adhesive Component Solution Xylitol, an adhesive component, was dissolved in ion-exchanged water to prepare a xylitol aqueous solution containing xylitol at a predetermined mass content. Next, the capacitor element was impregnated with the xylitol-containing solution, followed by a drying process, which allowed the conductive component layer to contain xylitol and form an electrolyte. The drying process was performed by heating the capacitor element at 135°C for 20 minutes. The impregnation with the xylitol aqueous solution and the drying process were repeated two or more times.

[0175] (f) Impregnation with Liquid Component An electrolyte solution (liquid component) was prepared by dissolving o-phthalic acid and triethylamine (base component) in a solvent at a total concentration of 25% by mass. The capacitor element was immersed in the electrolyte solution for 5 minutes in a reduced pressure atmosphere (40 kPa). This allowed the capacitor element to be impregnated with the electrolyte solution.

[0176] (g) Sealing of Capacitor Element The capacitor element containing 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 (Capacitor A1) was obtained.

[0177] (Capacitor A2) An electrolytic capacitor (capacitor A2) was produced in the same manner as capacitor A1, except that the xylitol concentration in the xylitol solution was changed.

[0178] (Capacitors A3 to A5, B1, B2) Except for changing the adhesive component to the component shown in Table 1, electrolytic capacitors (capacitors A3 to A5, B1, B2) were produced in the same manner as capacitor A1.

[0179] (Capacitors A6 to A7) Electrolytic capacitors (Capacitors A6 to A7) were produced in the same manner as Capacitor A1, except that at least a portion of the ion-exchanged water in the xylitol solution was replaced with a solvent (organic compound (C)) shown in Table 1.

[0180] (Capacitor C1) An electrolytic capacitor (capacitor C1) was produced in the same manner as capacitor A1, except that step (e) was omitted and the electrolyte was formed without including xylitol in the conductive component layer.

[0181] [Evaluation 1] (Peel Strength) The peel strength between the cathode foil and the separator was measured by the method described above, except for capacitor C1, whose peel strength was too small to be measured using the above-mentioned measuring device.

[0182] (Electrolyte Composition) The mass content (CX) of the adhesive component in the electrolyte, the mass content (CY) of the organic compound (C) in the electrolyte, and the ratio (Ma / Mp) of the mass Ma of the adhesive component to the mass Mp of the conductive component in the electrolyte were determined.

[0183] (ESR Measurement) The initial ESR of the initial electrolytic capacitor after the aging was measured. The measurement temperature was 20°C. Next, assuming reflow (RF), the electrolytic capacitor was heated at 200°C to 245°C for 70 seconds, and then the post-RF ESR was measured. The measurement temperature was 20°C. The relative value of the post-RF ESR, where the initial ESR is set to 1, is shown in Table 1.

[0184]

[0185] Capacitors B1, B2, and C1 are comparative examples, and the other capacitors are examples. Figure 4 shows the relationship between peel strength and post-RF ESR relative value. The results in Table 1 and Figure 4 indicate that the post-RF ESR relative values ​​of capacitor B1, which has a peel strength of 2.5 N / mm, and capacitor B2, which has a peel strength of 2.8 N / mm, are greater than the other capacitors with peel strengths of 3.0 N / mm or more. In other words, it can be seen that by setting the peel strength to 3.0 N / mm or more, an electrolytic capacitor with a small increase in post-RF ESR can be obtained.

[0186] The present disclosure can be used in solid electrolytic capacitors and solid-liquid hybrid electrolytic capacitors.

[0187] 10: Capacitor element 11: Anode foil 12: Cathode foil 13: Separator 14: Winding stop tape 20: Measuring device 21: Feeding sheet 22: Feeding roller 23: Recovery device 24: Fixing jig 100: Electrolytic capacitor 101: Bottomed case 102: Sealing member 103: Seat plate 104A, 104B: Lead wire 105A, 105B: Lead tab

Claims

1. Anode foil having a dielectric layer, Cathode foil and A separator interposed between the anode foil and the cathode foil, The system comprises an electrolyte interposed between the anode foil and the cathode foil and in contact with the separator, The electrolyte comprises a conductive component and an adhesive component. The conductive component comprises a conductive polymer and a dopant. At least a portion of the anode foil and at least a portion of the cathode foil are connected to the separator by the electrolyte. A capacitor element in which the peel strength between the cathode foil and the separator is 3.0 N / mm or more.

2. The capacitor element according to claim 1, wherein the adhesive component is at least one selected from the group consisting of sugar, sugar alcohol, epoxy resin, and polyvinyl alcohol.

3. The adhesive component is at least one selected from the group consisting of sugars and sugar alcohols. The capacitor element according to claim 1, wherein the mass content of the adhesive component in the total mass of the solid components of the electrolyte is 50% by mass or more.

4. The adhesive component is at least one selected from the group consisting of epoxy resin and polyvinyl alcohol. The capacitor element according to claim 1, wherein the mass content of the adhesive component in the total mass of the solid components of the electrolyte is 50% by mass or less.

5. The adhesive component is at least one selected from the group consisting of sugars and sugar alcohols. The capacitor element according to claim 1, wherein the ratio of the mass Ma of the adhesive component to the mass Mp of the conductive component (Ma / Mp) is 2 or more and 15 or less.

6. The adhesive component is at least one selected from the group consisting of epoxy resin and polyvinyl alcohol. The capacitor element according to claim 1, wherein the ratio of the mass Ma of the adhesive component to the mass Mp of the conductive component (Ma / Mp) is 0.01 or more and 10 or less.

7. A capacitor element according to claim 1, An electrolytic capacitor comprising a liquid component contained in the void within the capacitor element.

8. The electrolytic capacitor according to claim 7, wherein the liquid component comprises at least one selected from the group consisting of ethylene glycol, diethylene glycol, triethylene glycol, ethylene glycol condensate with a molecular weight of 250 or less, glycerin, γ-butyrolactone, and sulfolane.

9. Step (a) of preparing an anode foil having a dielectric layer, a cathode foil, and a separator, (b) A step of applying a coating liquid containing a conductive component and a liquid medium to at least one surface selected from the surface of the dielectric layer and the surface of the cathode foil, and into the void of the separator. (c) A step of removing at least a portion of the liquid medium from the coating liquid to deposit the conductive component onto the at least one surface and into the void of the separator, (d) A step of forming a capacitor element containing the conductive component by arranging the separator between the anode foil and the cathode foil, (e) A step of impregnating the capacitor element with a solution containing an adhesive component to form an electrolyte containing the conductive component and the adhesive component, and connecting at least a portion of the anode foil and at least a portion of the cathode foil to the separator with the electrolyte, This includes them in this order, The conductive component comprises a conductive polymer and a dopant. A method for manufacturing an electrolytic capacitor, wherein the peel strength between the cathode foil and the separator is 3.0 N / mm or more.

10. A method for manufacturing an electrolytic capacitor according to claim 9, further comprising the step of impregnating the void in the capacitor element with a liquid component after step (e).

11. Step (a) of preparing an anode foil having a dielectric layer, a cathode foil, and a separator, (b) A step of applying a coating liquid containing a conductive component, an adhesive component, and a liquid medium to at least one surface selected from the surface of the dielectric layer and the surface of the cathode foil, and into the void of the separator. (c) A step of removing at least a portion of the liquid medium from the coating liquid to form an electrolyte containing the conductive component and the adhesive component in the void of the at least one surface and the separator, (d) A step of forming a capacitor element including the electrolyte by arranging the separator between the anode foil and the cathode foil, and connecting at least a portion of the anode foil and at least a portion of the cathode foil to the separator with the electrolyte, This includes them in this order, The conductive component comprises a conductive polymer and a dopant. A method for manufacturing an electrolytic capacitor, wherein the peel strength between the cathode foil and the separator is 3.0 N / mm or more.

12. A method for manufacturing an electrolytic capacitor according to claim 11, further comprising the step of impregnating the void in the capacitor element with a liquid component after step (d).