Electrolytic capacitor and method for manufacturing electrolytic capacitor

Abstract

The electrolytic capacitor includes a laminate and a liquid component impregnated into the laminate. The laminate includes an anode foil having a dielectric layer formed on a surface thereof, a cathode foil, a separator, and a conductive polymer layer formed in the separator. The anode foil and the cathode foil are laminated with the separator interposed therebetween. In a log differential pore volume distribution curve of the separator on which the conductive polymer layer is formed, the log differential pore volume of the maximum peak is in the range of 1.0-2.3 cm3 / g.

Description

Technical Field

[0001] The present application relates to an electrolytic capacitor and a method for manufacturing an electrolytic capacitor. Background Art

[0002] Known electrolytic capacitors include capacitor elements having a solid electrolyte layer impregnated with an electrolyte. For example, Claim 1 of Patent Document 1 (International Publication No. 2011 / 099261) states, "An electrolytic capacitor comprising a capacitor element, an electrolyte impregnated into the capacitor element, and an outer casing enclosing the capacitor element and the electrolyte, wherein the capacitor element comprises an anode foil having a dielectric layer on its surface, a cathode foil, a separator interposed between the anode foil and the cathode foil, and a solid electrolyte layer in contact with the dielectric layer of the anode foil and the cathode foil, wherein the electrolyte contains a low-volatility solvent that is at least one of a polyalkylene glycol and a polyalkylene glycol derivative."

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: International Publication No. 2011 / 099261 Summary of the Invention

[0006] One aspect of the present application relates to an electrolytic capacitor. The electrolytic capacitor comprises a laminate and a liquid component impregnated into the laminate, wherein the laminate comprises an anode foil having a dielectric layer formed on its surface, a cathode foil, a separator, and a conductive polymer layer formed within the separator, wherein the maximum peak of the log differential pore volume distribution curve of the separator having the conductive polymer layer is within a range of 1.0 to 2.3 cm 3 / g range.

[0007] Another aspect of the present application relates to a method for manufacturing an electrolytic capacitor. The method is a method for manufacturing an electrolytic capacitor comprising an anode foil and a cathode foil having a dielectric layer formed on their surfaces, the method comprising: step (i) forming a conductive polymer layer in a separator using a coating liquid containing a conductive polymer component; step (ii) stacking the anode foil, the cathode foil, and the separator in a manner such that the separator is arranged between the anode foil and the cathode foil, thereby forming a laminate comprising the conductive polymer layer; and step (iii) impregnating the laminate with a liquid component, wherein in step (i), the maximum log differential pore volume of the log differential pore volume distribution curve of the separator having the conductive polymer layer formed thereon is within a range of 1.0 to 2.3 cm 3The conductive polymer layer is formed in a range of 1:1 / g.

[0008] According to the present application, an electrolytic capacitor including a conductive polymer and a liquid component and having a low ESR can be obtained. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 It is a cross-sectional view schematically showing an example of the electrolytic capacitor according to the present embodiment.

[0010] Figure 2 It is schematically represented Figure 1 An exploded perspective view of an example of a capacitor element used in an electrolytic capacitor.

[0011] Figure 3 It is a graph showing the results of Examples.

[0012] Figure 4 This is a graph showing an example of a log differential pore volume distribution curve. DETAILED DESCRIPTION

[0013] In electrolytic capacitors using a conductive polymer and a liquid component (electrolyte, etc.), there is a demand for reducing the equivalent series resistance (ESR). The present application provides an electrolytic capacitor comprising a conductive polymer and a liquid component and having low ESR.

[0014] Hereinafter, embodiments of the present invention will be described with examples, but the present invention is not limited to the examples described below. In the following description, specific numerical values ​​and materials are sometimes illustrated, but other numerical values ​​and other materials may also be applied as long as the invention of the present application can be implemented. In this specification, a description such as "numerical value A to numerical value B" includes numerical value A and numerical value B, and may be renamed as "above numerical value A and below numerical value B". In the following description, when the lower limit and upper limit of numerical values ​​for specific physical properties, conditions, etc. are illustrated, as long as the lower limit is not above the upper limit, any of the illustrated lower limits may be arbitrarily combined with any of the illustrated upper limits.

[0015] (Electrolytic capacitors)

[0016] The electrolytic capacitor of this embodiment is sometimes referred to as "electrolytic capacitor (E)" hereinafter. The electrolytic capacitor (E) includes a laminate and a liquid component impregnated into the laminate. The liquid component is sometimes referred to as "liquid component (L)" hereinafter. The laminate includes an anode foil having a dielectric layer formed on its surface, a cathode foil, a separator, and a conductive polymer layer formed within the separator. In the log differential pore volume distribution curve of the separator having the conductive polymer layer formed thereon, the log differential pore volume of the maximum peak is between 1.0 and 2.3 cm 3The log differential pore volume of the maximum peak may be hereinafter referred to as "maximum peak volume Vmax". The separator having the conductive polymer layer formed thereon may be hereinafter referred to as "polymer layer-containing separator".

[0017] A conductive polymer component and a liquid component (L) are placed between the anode and cathode foils of an electrolytic capacitor (E). This allows the electrolytic capacitor (E) to exhibit high performance. To achieve these high performances, a certain amount of conductive polymer must be placed between the anode and cathode foils. Previously, attempts have been made to place a larger amount of conductive polymer between the anode and cathode foils. However, as a result of these studies, the inventors of this application have discovered that increasing the amount of conductive polymer can reduce the ESR. Furthermore, the inventors of this application have discovered that by setting the maximum peak volume Vmax in the log differential pore volume distribution curve of a separator formed with a conductive polymer layer to a value within a predetermined range, the ESR can be significantly reduced. This application is based on these new insights.

[0018] The maximum peak volume Vmax of the spacer containing the polymer layer is 1.0 cm 3 / g, or 1.2cm 3 / g or more. The maximum peak volume Vmax is 2.3cm 3 / g or less, and can also be 1.8cm 3 / g or less. The maximum peak volume Vmax can be between 1.2 and 2.3 cm 3 / g range, 1.0~1.8cm 3 / g range, or 1.2~1.8cm 3 / g range.

[0019] It can be considered that by setting the maximum peak volume Vmax to 1.0 cm 3 / g or more, the liquid component (L) easily penetrates into the interior of the separator. As a result, it is believed that the liquid component (L) is well dispersed in the separator, and the ESR is reduced. It is believed that by setting the maximum peak volume Vmax to 2.3cm 3 / g or less, it is possible to suppress an increase in ESR due to an excessively small amount of the conductive polymer component.

[0020] The average pore diameter at which the log differential pore volume distribution curve reaches the maximum peak volume Vmax may be, for example, in the range of 1 μm to 50 μm, 1 μm to 30 μm, 5 μm to 30 μm, or 5 μm to 10 μm.

[0021] The log differential pore volume distribution curve (dV / d(logD)) is obtained by dividing the differential pore volume dV by the logarithm of the difference d(logD) of the pore diameter and plotting this value against the average pore diameter for each interval. The log differential pore volume distribution curve can be obtained for pores with diameters ranging from 1 μm to 100 μm. The log differential pore volume distribution curve is the log differential pore volume distribution curve for a dry polymer layer-containing separator. Specifically, the maximum peak volume Vmax is determined by measuring the log differential pore volume distribution curve of a polymer layer-containing separator that has not been impregnated with a liquid component (L). The log differential pore volume distribution curve can be measured using mercury porosimetry, as described in the Examples.

[0022] To measure the log differential pore volume distribution curve of a polymer layer-containing separator within an electrolytic capacitor, first remove the polymer layer-containing separator from the capacitor and immerse it in ethanol to cleanse the liquid component. The cleaned separator is then heated at 100°C for 1 hour to dry it. The log differential pore volume distribution curve is then measured.

[0023] The log differential pore volume of the maximum peak in the log differential pore volume distribution curve of a single separator (a separator without a conductive polymer layer formed thereon) (hereinafter sometimes referred to as "maximum peak volume Vs") may be 2.5 cm 3 / g or above, or 2.9cm 3 / g or more, and can be 10cm 3 / g or less, or 8cm 3 / g or less.

[0024] The laminate may further include a second conductive polymer layer formed on at least one surface selected from the dielectric layer (the surface of the anode foil) and the surface of the cathode foil. The conductive polymer component constituting the conductive polymer layer (the first conductive polymer layer) formed in the separator may be the same as or different from the conductive polymer component constituting the second conductive polymer layer. In the case where the conductive polymer layer is formed on both the surface of the dielectric layer and the cathode foil, the conductive polymer components forming these two conductive polymer layers may be the same or different. The conductive polymer layers formed on each component may contain the same conductive polymer component or may be composed of the same conductive polymer component. The first conductive polymer layer and the second conductive polymer layer may be in contact at the interface. At their interface, there may be a mixed region where the first conductive polymer layer and the second conductive polymer layer are mixed.

[0025] The electrolytic capacitor (E) may contain an organic compound (C) impregnated into the conductive polymer layer formed in the separator. The organic compound (C) is an organic compound that does not boil at 100°C under 1 atmosphere. Examples of the organic compound (C) will be described later.

[0026] (Method for Manufacturing Electrolytic Capacitors)

[0027] Hereinafter, the method for manufacturing an electrolytic capacitor according to this embodiment may be referred to as "manufacturing method (M)." The electrolytic capacitor (E) can be manufactured using the manufacturing method (M). However, the electrolytic capacitor (E) may also be manufactured using methods other than the manufacturing method (M). Since the matters described for the electrolytic capacitor (E) can be applied to the manufacturing method (M), duplicate descriptions may be omitted. The matters described for the manufacturing method (M) can also be applied to the electrolytic capacitor (E).

[0028] Manufacturing method (M) is a method for manufacturing an electrolytic capacitor comprising an anode foil and a cathode foil with a dielectric layer formed on their surfaces. Manufacturing method (M) sequentially comprises steps (i), (ii), and (iii). These steps are described below.

[0029] (Process (i))

[0030] Step (i) is a step of forming a conductive polymer layer in the separator using a coating liquid containing a conductive polymer component. In step (i), the maximum peak volume Vmax in the log differential pore volume distribution curve of the separator formed with the conductive polymer layer is set to a value between 1.0 and 2.3 cm 3 The conductive polymer layer is formed in a range of 1:1 / g.

[0031] In step (i), a conductive polymer layer is formed on the separator before the laminate is loaded. Therefore, unlike the method of impregnating the laminate with the coating liquid after the laminate is formed, in step (i), more conductive polymer components can be arranged in the separator. However, the inventors of the present application found that if too much conductive polymer component is arranged in the separator, the ESR may increase. The reason is not clear at present, but it can be considered that if too much conductive polymer component is arranged in the separator, the liquid component (L) will not fully penetrate into the separator, and as a result, the affinity of the conductive polymer component to the surface of the electrode foil (the dielectric layer on the surface of the anode foil, the surface of the cathode foil) is reduced. On the other hand, if too little conductive polymer component is arranged in the separator, the effect of reducing ESR brought about by the conductive polymer component becomes smaller, and the ESR increases. By making the maximum peak volume Vmax of the separator containing the polymer layer be between 1.0 and 2.3 cm as described above. 3By forming the conductive polymer layer in a range of 1 / g, the ESR can be reduced.

[0032] Step (i) may include step (ia) and step (ib). Step (ia) is a step of applying a coating liquid containing a conductive polymer component and a liquid medium to the separator. Step (ib) is a step of removing at least a portion of the liquid medium from the applied coating liquid to form a conductive polymer layer within the separator.

[0033] The liquid medium may contain water or may be water. Examples of the conductive polymer component will be described later. The conductive polymer component may be dispersed in the coating liquid in the form of particles.

[0034] The coating method of the coating liquid is not limited and can be applied by a known method. For example, a method using a coating machine can be used, the coating liquid can be sprayed, or the coated object can be immersed in the coating liquid. Examples of methods using a coating machine include gravure coating, die coating, etc. It should be noted that the method of applying the coating liquid to the spacer includes a method of impregnating the spacer with the coating liquid. The coating liquid applied to the spacer penetrates into the interior of the spacer and can form a conductive polymer layer in the entire thickness direction of the spacer.

[0035] The method for removing the liquid medium in step (ib) is not limited. The removal of the liquid medium can be carried out by heating and / or reducing pressure, preferably at least heating. The heating temperature can be 100°C or higher, 120°C or higher, or 140°C or higher, and can be 200°C or lower, or 160°C or lower. The heating temperature can 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 can appropriately remove a portion of the liquid medium. In one example, the heating time is in the range of 5 to 60 minutes.

[0036] The maximum peak volume Vmax of the spacer containing the polymer layer can be changed by changing the concentration of the conductive polymer component in the coating liquid, the coating amount of the coating liquid, and the maximum peak volume Vs of the independent spacer. The maximum peak volume Vs of the independent spacer can be changed by changing the void ratio of the independent spacer that does not form a conductive polymer layer. By increasing the concentration of the conductive polymer component in the coating liquid, the maximum peak volume Vmax can be reduced. By increasing the coating amount of the coating liquid, the maximum peak volume Vmax can be reduced. By reducing the maximum peak volume Vs of the independent spacer, the maximum peak volume Vmax can be reduced. For example, by reducing the void ratio of the spacer, the maximum peak volume Vmax can be reduced.

[0037] As described above, a second conductive polymer layer can be formed on at least one surface (S) selected from the dielectric layer (the surface of the anode foil) and the surface of the cathode foil. The second conductive polymer layer can be formed using the same method as described in steps (ia) and (ib) above.

[0038] In step (i), a conductive polymer layer can be formed on the surface of the dielectric layer (the dielectric layer on the anode foil), the surface of the cathode foil, and the separator. This configuration allows the conductive polymer layer to be formed continuously from the dielectric layer to the cathode foil facing the dielectric layer.

[0039] Hereinafter, the conductive polymer layer formed in the separator may be referred to as a “first conductive polymer layer.” The first conductive polymer layer may be formed on the surface of the fiber or microporous membrane constituting the separator.

[0040] The first conductive polymer layer and the second conductive polymer layer may be composed of the same conductive polymer component or different conductive polymer components. The first conductive polymer layer formed within the separator, the second conductive polymer layer formed on the anode foil (on the dielectric layer), and the second conductive polymer layer formed on the cathode foil may be composed of the same conductive polymer component or different conductive polymer components. In one example, they contain the same conductive polymer component.

[0041] (Process (ii))

[0042] Step (ii) is a step of forming a laminate including a conductive polymer layer by laminating an anode foil, a cathode foil, and a separator with the separator disposed between the anode foil and the cathode foil.

[0043] The method for forming the laminate is not limited, and the laminate can be formed using known methods. The laminate can be a wound body. In this case, in step (ii), the wound body can be formed by winding the anode foil, cathode foil, and separator with the separator disposed between the anode foil and the cathode foil. In the wound body, the anode foil, cathode foil, and separator are stacked in the radial direction of the wound body.

[0044] The laminate can also be formed by stacking a flat anode foil, a flat cathode foil, and a flat separator in one direction. For example, a plurality of anode foils, a plurality of cathode foils, and a plurality of separators can be stacked in one direction to form the laminate. In a typical example of such a laminate, the anode foils and the cathode foils are alternately arranged, and the separator is arranged between the anode foils and the cathode foils.

[0045] (Process (iii))

[0046] Step (iii) is a step of impregnating the laminate (e.g., the conductive polymer layer in the laminate) with a liquid component. The liquid component is the liquid component (L) described above. The method for impregnating the laminate with the liquid component (L) is not limited. For example, the laminate can be impregnated with the liquid component (L) by immersing at least a portion of the laminate in the liquid component (L). Alternatively, the laminate can be placed in an outer packaging and then the liquid component (L) can be injected into the outer packaging to impregnate the laminate (L). Examples of the liquid component (L) will be described later.

[0047] (Coating liquid)

[0048] The coating liquid used in step (i) comprises a conductive polymer component and a liquid medium. The coating liquid may also contain other components as needed. The liquid medium may contain water or be water alone. The coating liquid may be a dispersion of particles of the conductive polymer component.

[0049] The conductive polymer component may contain a conductive polymer or may consist solely of a conductive polymer. Alternatively, the conductive polymer component may contain a conductive polymer and a dopant.

[0050] Examples of conductive polymers include polypyrrole, polythiophene, polyfuran, polyaniline, polyacetylene and their derivatives. The derivatives include polymers with polypyrrole, polythiophene, polyfuran, polyaniline and polyacetylene as the basic skeleton. For example, derivatives of polythiophene include poly(3,4-ethylenedioxythiophene) and the like. These conductive polymers can be used alone or in combination. In addition, the conductive polymer can be a copolymer of two or more monomers. The weight average molecular weight of the conductive polymer is not particularly limited, for example, it can be in the range of 1000 to 100000. A preferred example of a conductive polymer is poly(3,4-ethylenedioxythiophene) (PEDOT).

[0051] The conductive polymer may be doped with a dopant. From the perspective of suppressing dedoping from the conductive polymer, a polymer dopant is preferably used as the dopant. Examples of polymer dopants include polyvinylsulfonic acid, polystyrenesulfonic acid, polyallylsulfonic acid, polyacrylic acid sulfonic acid, polymethacrylic acid sulfonic acid, poly(2-acrylamide-2-methylpropanesulfonic acid), polyisoprenesulfonic acid, and polyacrylic acid. 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 a dopant is polystyrenesulfonic acid (PSS).

[0052] The dopant may be a dopant containing an acidic group or a polymer dopant containing an acidic group. Examples of acidic groups include sulfonic acid groups and carboxyl groups. A polymer dopant containing an acidic group is a polymer (polymer) in which at least a portion of its structural units contain an acidic group. Examples of such polymer dopants include the polymer dopants mentioned above.

[0053] The weight average molecular weight of the dopant is not particularly limited, but from the viewpoint of facilitating the formation of a uniform conductive polymer layer, the weight average molecular weight of the dopant can be set in the range of 1,000 to 100,000.

[0054] The dopant may be polystyrenesulfonic acid, and the conductive polymer may be poly(3,4-ethylenedioxythiophene). In other words, the conductive polymer component may be poly(3,4-ethylenedioxythiophene) doped with polystyrenesulfonic acid.

[0055] When using a conductive polymer doped with a dopant, the pH of the coating solution is preferably less than 7.0 to suppress dedoping of the dopant, but may be 6.0 or less or 5.0 or less. The pH of the coating solution may be 1.0 or more or 2.0 or more.

[0056] The conductive polymer component may be present in the coating liquid in the form of particles. In the volume-based particle size distribution of the conductive polymer component particles, the mode of the particle diameter may be 10 nm or greater, or 20 nm or greater, and 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.

[0057] The water content in the coating liquid may be 50% by mass or more, 80% by mass or more, 90% by mass or more, 94% by mass or more, 95% by mass or more, 96% by mass or more, or 97% by mass or more. The water content may also be 99.5% by mass or less. The water content may be in the range of 50-99.5% by mass, 94-99.5% by mass, 95-99.5% by mass, 96-99.5% by mass, or 97-99.5% by mass.

[0058] The content of the conductive polymer component in the coating liquid can be 0.5% by mass or more, or 1.0% by mass or more, and can be 6.0% by mass or less, 5.0% by mass or less, 4.0% by mass or less, 3.0% by mass or less, or 2.0% by mass or less. The content can be in the range of 0.5 to 6.0% by mass, or in the range of 1.0 to 6.0% by mass. In any of these ranges, the upper limit can be set to 5.0% by mass, 4.0% by mass, 3.0% by mass, or 2.0% by mass. From the perspective of excellent physical properties of the coating liquid and its stability over time, 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%. It should be noted that when the coating liquid contains a dopant, the mass of the dopant is included in the mass of the conductive polymer component.

[0059] The mass of the dopant contained in the coating liquid is not particularly limited, and may be in the range of 0.1 to 5 times (eg, 0.5 to 3 times) the mass of the conductive polymer contained in the coating liquid.

[0060] (Liquid content (L))

[0061] Examples of the liquid component (L) used in step (iii) include non-aqueous solvents and electrolytes. The electrolyte can include a non-aqueous solvent and a solute dissolved in the non-aqueous solvent. It should be noted that in this specification, the liquid component (L) may be a component that is liquid at room temperature (25°C) or at the temperature at which the electrolytic capacitor is used.

[0062] The nonaqueous solvent used in the liquid component (L) may be an organic solvent, an ionic liquid, or a protic solvent. Examples of nonaqueous solvents include polyols such as ethylene glycol, propylene glycol, and 1,3-butanediol; 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.

[0063] In addition, a polymer solvent can also be used as a non-aqueous solvent. Examples of polymer solvents include polyalkylene glycol, derivatives of polyalkylene glycol, compounds in which at least one hydroxyl group in a polyol is replaced with a polyalkylene glycol (including derivatives), etc. Specifically, examples of polymer solvents include polyethylene glycol (PEG), polyethylene glycol glycerol ether, polyethylene glycol diglycerol ether, polyethylene glycol sorbitol ether, polypropylene glycol, polypropylene glycol glycerol ether, polypropylene glycol diglycerol ether, polypropylene glycol sorbitol ether, polybutylene glycol, etc. Examples of polymer solvents further include ethylene glycol-propylene glycol copolymers, ethylene glycol-butylene glycol copolymers, propylene glycol-butylene glycol copolymers, etc. The non-aqueous solvent can be used alone or as a mixture of two or more.

[0064] The liquid component (L) may contain a non-aqueous solvent and an alkaline component (base) dissolved in the non-aqueous solvent. Alternatively, the liquid component (L) may contain a non-aqueous solvent and an alkaline component and / or an acid component (acid) dissolved in the non-aqueous solvent.

[0065] As the acid component, polycarboxylic acids and monocarboxylic acids can be used. Examples of the polycarboxylic acids 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); and unsaturated polycarboxylic acids such as maleic acid, fumaric acid, and itaconic acid), aromatic polycarboxylic acids (such as phthalic acid, isophthalic acid, terephthalic acid, trimellitic acid, and pyromellitic acid), and alicyclic polycarboxylic acids (such as cyclohexane-1,2-dicarboxylic acid and cyclohexene-1,2-dicarboxylic acid).

[0066] Examples of the monocarboxylic acid include aliphatic monocarboxylic acids (having 1 to 30 carbon atoms) ([saturated monocarboxylic acids, such as formic acid, acetic acid, propionic acid, butyric acid, isobutyric acid, valeric acid, hexanoic acid, heptanoic acid, octanoic acid, nonanoic 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 hydroxycarboxylic acids (such as salicylic acid, mandelic acid, and resorcinol).

[0067] Among them, maleic acid, phthalic acid, benzoic acid, pyromellitic acid, and resorbic acid are preferably used because they are thermodynamically stable.

[0068] Inorganic acids may also be used as the acid component. Representative examples of inorganic acids include phosphoric acid, phosphorous acid, hypophosphorous acid, alkyl phosphates, boric acid, fluoroboric acid, tetrafluoroboric acid, hexafluorophosphoric acid, benzenesulfonic acid, and naphthalenesulfonic acid. Furthermore, composite compounds of organic and inorganic acids may also be used as the acid component. Examples of such composite compounds include boron diglycolic acid, boron dioxalic acid, and boron disalicylic acid.

[0069] 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 (pyrimidine compound, imidazoline compound). Specifically, preferred are 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-ethylimidazoline, 1,4-dimethyl-2-ethylimidazoline, 1-methyl-2-heptylimidazoline, 1-methyl-2-(3'heptyl)imidazoline, 1-methyl-2-dodecylimidazoline, 1,2-dimethyl-1,4,5,6-tetrahydropyrimidine, 1-methylimidazole, and 1-methylbenzimidazole. Using these compounds can produce capacitors with excellent impedance performance.

[0070] A quaternary salt of a compound having an alkyl-substituted amidine group can also be used as the base component. Examples of such base components include imidazole compounds, benzimidazole compounds, and alicyclic amidine compounds (pyrimidine compounds, imidazoline compounds) quaternized with an alkyl or arylalkyl group having 1 to 11 carbon atoms. Specifically, preferred are 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-ethylimidazolinium, 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-tetrahydropyrimidinium, 1,3-dimethylimidazolium, 1-methyl-3-ethylimidazolium, and 1,3-dimethylbenzimidazolium. By using these, a capacitor having excellent impedance performance can be obtained.

[0071] Alternatively, tertiary amines 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-containing amines (dimethylaniline, methylethylaniline, diethylaniline, etc.). Among these, trialkylamines are preferred due to their improved conductivity, and more preferably, the base component contains at least one selected from trimethylamine, dimethylethylamine, methyldiethylamine, and triethylamine. Alternatively, secondary amines such as dialkylamines, primary amines such as monoalkylamines, and ammonia may also be used as the base component.

[0072] The liquid component (L) 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 cation contains an organic substance. Examples of organic salts include trimethylamine maleate, triethylamine borodisalicylate, ethyldimethylamine phthalate, mono-1,2,3,4-tetramethylimidazolinium phthalate, and mono-1,3-dimethyl-2-ethylimidazolinium phthalate.

[0073] To suppress dedoping of the dopant, the pH of the liquid component (L) may be set to less than 7.0 or less than 5.0, or may be set to 1.0 or more, or 2.0 or more. The pH may be set to 1.0 or more and less than 7.0 (e.g., in the range of 2.0 to 5.0).

[0074] The liquid component (L) preferably contains a protic solvent. A high effect can be obtained by containing a protic solvent in the liquid component (L). The liquid component (L) may contain a solvent other than the protic solvent in addition to the protic solvent.

[0075] The protic solvent may contain at least one selected from glycols, glycerol, polyglycerol, and sugar alcohols, or may be the at least one. The protic solvent may be composed of only one compound or may contain a plurality of compounds.

[0076] The organic compound (C) and the liquid component (L) may contain the same compound. For example, they may contain the same protic solvent, the same polyol, the same diol (such as ethylene glycol), or the same sugar alcohol.

[0077] The manufacturing method (M) may include the steps (x) and (y) in sequence between the steps (ii) and (iii). By performing the steps (x) and (y), the ESR can be further reduced.

[0078] (Process (x))

[0079] Step (x) involves impregnating the conductive polymer layer in the laminate with a liquid containing water and an organic compound (C) that does not boil at 100°C under 1 atmosphere (101325 Pa). This liquid may be hereinafter referred to as "liquid (S)." The main component (content: 50% by mass or greater) of the liquid (S) may be water.

[0080] The method for impregnating the conductive polymer layer with the liquid (S) is not limited. For example, the conductive polymer layer can be impregnated with the liquid (S) by immersing at least a portion of the laminate in the liquid (S). By setting the maximum peak volume Vmax within the above range, the liquid (S) easily permeates the conductive polymer layer, and ESR can be particularly reduced.

[0081] (Liquid(s))

[0082] As described above, the liquid (S) contains water and the organic compound (C). The liquid (S) may consist solely of water and the organic compound (C), or may contain other components. An organic compound that is readily soluble in water is preferably used as the organic compound (C). The organic compound (C) may be a compound miscible with water. Examples of the organic compound (C) include compounds used as organic solvents. Examples of the organic compound (C) include polyols having two or more hydroxyl groups.

[0083] The liquid (S) may or may not contain a conductive polymer. Since the liquid (S) acts on the conductive polymer layer, it is preferred that the liquid (S) contain substantially no conductive polymer. For example, the conductive polymer content in the liquid (S) may be less than 0.5% by mass or less than 0.1% by mass. If the liquid (S) contains a conductive polymer component, the conductive polymer component contained in the conductive polymer layer and the conductive polymer component contained in the liquid (S) may be the same or different.

[0084] Unless otherwise specified, the boiling point in this specification refers to the boiling point at 1 atmosphere. Examples of the organic compound (C) include organic compounds having a boiling point higher than 100°C. If 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 within the range of 110°C to 400°C (e.g., 150°C to 350°C).

[0085] Examples of the organic compound (C) include polyols, sulfolane, γ-butyrolactone, and boric acid esters. The organic compound (C) may contain at least one selected from the group consisting of polyols, sulfolane, γ-butyrolactone, and boric acid esters, or may be the at least one selected from the group consisting of glycols, glycerols, sugar alcohols, sulfolane, γ-butyrolactone, and boric acid esters, or may be the at least one selected from the group consisting of glycols, glycerols, sugar alcohols, sulfolane, γ-butyrolactone, and boric acid esters.

[0086] Examples of polyols include glycols, glycerols, and sugar alcohols. Examples of glycols include ethylene glycol, diethylene glycol, triethylene glycol, polyalkylene glycols (e.g., polyethylene glycol), polyoxyethylene polyoxypropylene glycol (ethylene oxide-propylene oxide copolymer), etc. Examples of glycerols include glycerol and polyglycerol. Examples of sugar alcohols include mannitol, xylitol, sorbitol, erythritol, and pentaerythritol.

[0087] The organic compound (C) may be a protic solvent. Examples of protic solvents will be described later. As the organic compound (C), diols (such as ethylene glycol) are preferred in terms of obtaining high effects.

[0088] The water content in the liquid (S) is, for example, 40% by mass or more, and may be 50% by mass or more, 70% by mass or more, 90% by mass or more, or 95% by mass or more. This content is preferably 99% by mass or less, or 98% by mass or less, and may also be 95% by mass or less, 90% by mass or less, 80% by mass or less, or 50% by mass or less. This content may be in the range of 40% to 99% by mass, 50% to 99% by mass, 70% to 99% by mass, or 90% to 99% by mass. Within any of these ranges, as long as the lower limit is not greater than the upper limit, the upper limit may be replaced by 98% by mass, 95% by mass, 90% by mass, 80% by mass, or 50% by mass.

[0089] The content of the organic compound (C) in the liquid (S) may be 1% by mass or more, 2% by mass or more, 3% by mass or more, 5% by mass or more, 10% by mass or more, or 20% by mass or more. The content may be 60% by mass or less, 50% by mass or less, 40% by mass or less, or 30% by mass or less. The content may be in the range of 1-60% by mass, 2-60% by mass, 3-60% by mass, 5-60% by mass, or 10-60% by mass. Within any of these ranges, the upper limit may be 50% by mass, 30% by mass, 25% by mass, or 20% by mass. The content is preferably in the range of 2-50% by mass, and more preferably in the range of 5-50% by mass.

[0090] In the liquid (S), the content rate (mass %) of water and the content rate (mass %) of the organic compound (C) may be in the range of water content rate:organic compound (C) content rate = 99:1 (or 98:2) to 50:50 (or 60:40).

[0091] (Process (y))

[0092] Step (y) is a step of removing a portion of the liquid impregnated into the conductive polymer layer so that the organic compound (C) remains in the conductive polymer layer. The time between step (x) and step (y) is not particularly limited; step (y) may be performed immediately after step (x). Alternatively, step (y) may be performed after a period of time ranging from 1 to 360 minutes (e.g., 5 to 180 minutes) has passed since step (x).

[0093] If all of the liquid (S) is removed, the conductive polymer layer shrinks significantly. Excessive shrinkage of the conductive polymer layer increases the equivalent series resistance (ESR) of the electrolytic capacitor. Furthermore, if the conductive polymer layer shrinks significantly, causing the dielectric film formed on the surface of the anode foil to be covered with dense conductive polymer, the liquid component (L), described later, becomes less likely to come into contact with the surface of the dielectric layer. As a result, the liquid component (L) cannot fully function to form the dielectric layer (oxide film), potentially causing increased leakage current or short circuits. By removing the liquid (S) while leaving only the organic compound (C), it is possible to manufacture an electrolytic capacitor with low ESR and leakage current, resulting in high reliability.

[0094] Steps (x) and (y) are preferably performed so that the mass of the organic compound (C) in the conductive polymer layer, as a result of step (y), is greater than the mass of the water in the conductive polymer layer. Specifically, after step (y) and before the other steps, the mass of the organic compound (C) in the conductive polymer layer is preferably greater than the mass of the water in the layer. If the amount of water remaining in the conductive polymer layer increases, the characteristics of the electrolytic capacitor deteriorate. Therefore, in step (y), it is preferred to remove a portion of the liquid (S) so that the amount of water remaining in the conductive polymer layer is reduced.

[0095] Removal of the liquid (S) can be performed by heating and / or reducing pressure, with at least heating being preferred. When heating is performed, it is preferred to remove a portion of the liquid (S) by heating the laminate 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 (S). The heating temperature is preferably a temperature at which the organic compound (C) does not boil or decompose. If the organic compound (C) does not have a clear boiling point, heating is preferably performed at a temperature at which evaporation of the organic compound (C) is minimal and decomposition of the organic compound (C) is minimized. The heating temperature may be 100°C or higher, 120°C or higher, or 140°C or higher, and may be 250°C or lower, 200°C or lower, or 160°C or lower. The heating temperature may be in the range of 100-200°C (e.g., 100-160°C). The heating time is not particularly limited, as long as a portion of the liquid (S) can be adequately removed. An example heating time is 5-60 minutes.

[0096] Steps (x) and (y) can be performed so that the ratio Wc / Wp of the mass Wc of the organic compound (C) remaining in the conductive polymer layer to the mass Wp of the conductive polymer component in the conductive polymer layer is 1.0 to 20. The ratio Wc / Wp can be 1.0 to 20, 1.2 to 1.2, or 2.0 to 2.0, and 20 to 20, or 18 to 18. The ratio Wc / Wp can also be 1.0 to 20, 1.2 to 18, or 2.0 to 18. By setting the ratio Wc / Wp to 2.0 to 18, an electrolytic capacitor with particularly excellent characteristics can be obtained. To increase Wc / Wp, it is sufficient to increase the content of the organic compound (C) in the liquid (S) or to increase the amount of liquid (S) applied.

[0097] In step (y), a portion of the liquid (S) is removed so that the ratio of the mass Ww of water in the conductive polymer layer to the mass Wc of the organic compound (C) in the conductive polymer layer, Ww / Wc, is less than 1. Ww / Wc can be 0 or greater, 0.001 or greater, 0.1 or greater, or 0.2 or greater, and can be 0.9 or less, 0.8 or less, 0.5 or less, 0.2 or less, 0.1 or less, or 0.005 or less. To reduce Ww / Wc, for example, methods such as increasing the content of the organic compound (C) in the liquid (S), reducing the water content in the liquid (S), or performing step (y) under conditions where water is preferentially evaporated can be used.

[0098] The mass Ww can be measured by Karl Fischer titration, and the mass Wp can be calculated from the concentration of the conductive polymer component in the dispersion (coating liquid) containing the conductive polymer component and the mass of the dispersion used to form the conductive polymer layer.

[0099] The mass Wc is calculated according to the following steps. First, the mass W0 (initial) of the laminate (capacitor element) is measured after the laminate formation step and before the liquid application step. Next, the mass W1 (after treatment) of the laminate is measured after the liquid application and removal steps. The mass Wc can then be calculated based on the difference (W1-W0) between the post-treatment mass W1 and the initial mass W0. If most of the water in the liquid (S) impregnating the laminate is removed by the removal step, the mass difference (W1-W0) can be considered as the mass Wc. It should be noted that the mass Ww of the water remaining in the conductive polymer layer can also be determined using Karl Fischer titration, with (W1-W0-Ww) being Wc.

[0100] The following describes an example of the structure and components of an electrolytic capacitor (E). This example includes a capacitor element, an outer package, an anode lead terminal, and a cathode lead terminal. It should be noted that the structure and components of an electrolytic capacitor (E) are not limited to the following example.

[0101] An electrolytic capacitor (E) comprises a laminate and a liquid component (L) impregnated into the laminate. The laminate comprises a conductive polymer layer. The laminate functions as a capacitor element. The laminate comprises an anode foil with a dielectric layer formed on its surface, a cathode foil, and a separator positioned between the anode and cathode foils. The anode and cathode foils face each other with the separator interposed therebetween. Electrolytic capacitors (E) typically include an outer casing to enclose the laminate.

[0102] An electrolytic capacitor includes at least one capacitor element, and may include a plurality of capacitor elements. The number of capacitor elements included in the electrolytic capacitor may be determined according to the intended use.

[0103] (Anode foil)

[0104] Examples of anode foil include metal foil containing at least one valve metal such as titanium, tantalum, aluminum, and niobium. Alternatively, a metal foil containing a valve metal (e.g., aluminum foil) may be used. The anode foil may contain the valve metal in the form of an alloy or compound containing the valve metal. The thickness of the anode foil may be between 15 μm and 300 μm. The surface of the anode foil may be roughened by etching or the like.

[0105] A dielectric layer is formed on the surface of the anode foil. The dielectric layer can be formed by subjecting the anode foil to a chemical conversion treatment. In this case, the dielectric layer can include a valve metal oxide (e.g., aluminum oxide). It should be noted that the dielectric layer can be formed of a dielectric other than a valve metal oxide, as long as it functions as a dielectric.

[0106] In an electrolytic capacitor, a conductive polymer layer may not be formed on the end surface of the anode foil. On the other hand, a dielectric layer is preferably formed on the end surface of the anode foil.

[0107] (Cathode foil)

[0108] The cathode foil is not particularly limited as long as it functions as a cathode. Examples of 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 between 15 μm and 300 μm. The surface of the cathode foil may be roughened or subjected to a chemical treatment as needed.

[0109] The cathode foil may include a conductive coating. When the metal foil used in the cathode foil includes a valve-action metal, the coating may include carbon and at least one metal with a lower ionization tendency than the valve-action metal. This facilitates improving the acid resistance of the metal foil. When the metal foil includes aluminum, the coating may include at least one selected from carbon, nickel, titanium, tantalum, and zirconium. For cost and electrical resistance considerations, the coating may include nickel and / or titanium.

[0110] The thickness of the coating layer may be 5 nm or more, or 10 nm or more, and may be 200 nm or less. The coating layer may be formed by vapor-depositing or sputtering the aforementioned metal onto the metal foil. Alternatively, the coating layer may be formed by vapor-depositing a conductive carbon material onto the metal foil, or by applying a carbon paste containing the conductive carbon material onto the metal foil. Examples of conductive carbon materials include graphite, hard carbon, soft carbon, carbon black, and the like.

[0111] (Spacer)

[0112] A porous sheet can be used as the spacer. Examples of porous sheets include woven fabrics, non-woven fabrics, and microporous membranes. A preferred example of a porous sheet is a non-woven fabric. The thickness of the spacer is not particularly limited and can be in the range of 10 to 300 μm. Examples of materials for the spacer include cellulose, polyethylene terephthalate, polybutylene terephthalate, polyphenylene sulfide, vinylon, nylon, aromatic polyamide, polyimide, polyamideimide, polyetherimide, rayon, and glass.

[0113] (Outer packaging)

[0114] The outer packaging body includes an outer shell and / or a sealing resin. The outer shell and sealing resin are not limited thereto, and known outer shells and sealing resins can be used. The sealing resin can include a thermosetting resin. Examples of thermosetting resins include epoxy resins, phenolic resins, silicone resins, melamine resins, urea resins, alkyd resins, polyurethanes, polyimides, and unsaturated polyesters. The sealing resin can also include fillers, curing agents, polymerization initiators, and / or catalysts.

[0115] An example of this embodiment is described below in detail with reference to the accompanying drawings. The components of the example described below can be applied to the components described above. Furthermore, the components of the example described below can be modified based on the above description. Furthermore, the matters described below can be applied to the above embodiment. Furthermore, in the example described below, components that are not essential to the electrolytic capacitor of this application can be omitted.

[0116] (Implementation Method 1)

[0117] Figure 1 1 is a cross-sectional view schematically showing an electrolytic capacitor 100 according to an example of the first embodiment. Figure 2 1 is a schematic diagram showing a partial development of capacitor element 10 included in electrolytic capacitor 100 .

[0118] Electrolytic capacitor 100 includes a capacitor element 10, a bottomed case 101 housing capacitor element 10, a sealing member 102 sealing the opening of bottomed case 101, a base plate 103 covering sealing member 102, leads 104A and 104B extending from sealing member 102 and penetrating base plate 103, and lead tabs 105A and 105B connecting the leads to electrodes of capacitor element 10. The area near the open end of bottomed case 101 is drawn inward and then crimped to secure the open end to sealing member 102.

[0119] The capacitor element 10 is, for example, Figure 1 The wound body is shown. 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 (wound body) 10 includes a conductive polymer layer (not shown) formed within separator 13. The maximum peak volume Vmax of separator 13 formed with the conductive polymer layer is within the above range. Electrolytic capacitor 100 includes a liquid component (L) (e.g., an electrolyte solution) impregnated into capacitor element 10.

[0120] A dielectric layer (not shown) is formed on the surface of the anode foil 11. 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 by a winding fixing tape 14. Figure 2 The diagram shows a partially unfolded state before the outermost circumference of the wound body is fixed.

[0121] (Note)

[0122] The following technologies are disclosed through the above description.

[0123] (Technique 1)

[0124] An electrolytic capacitor comprising a laminate and a liquid component impregnated into the laminate.

[0125] The laminate includes an anode foil having a dielectric layer formed on its surface, a cathode foil, a separator, and a conductive polymer layer formed in the separator.

[0126] The anode foil and the cathode foil are stacked with the separator interposed therebetween.

[0127] In the log differential pore volume distribution curve of the separator having the conductive polymer layer formed thereon, the log differential pore volume of the maximum peak is in the range of 1.0 to 2.3 cm 3 / g range.

[0128] (Technique 2)

[0129] A method for manufacturing an electrolytic capacitor, comprising an anode foil and a cathode foil having a dielectric layer formed on their surfaces, the method comprising:

[0130] Step (i), forming a conductive polymer layer in the spacer using a coating liquid containing a conductive polymer component;

[0131] Step (ii) of laminating the anode foil, the cathode foil, and the separator with the separator disposed between the anode foil and the cathode foil to form a laminate including the conductive polymer layer; and

[0132] Step (iii), impregnating the above-mentioned laminate with a liquid component,

[0133] In the step (i), the maximum peak of the log differential pore volume distribution curve of the separator having the conductive polymer layer formed thereon is 1.0 to 2.3 cm 3 The conductive polymer layer is formed in a range of 1:1 / g.

[0134] (Technique 3)

[0135] According to the manufacturing method described in technology 2,

[0136] Between the above steps (ii) and (iii), the method further comprises:

[0137] Step (x), impregnating the conductive polymer layer with a liquid containing water and an organic compound that does not boil at 100° C. under 1 atmosphere; and

[0138] Step (y) of removing a portion of the liquid impregnated into the conductive polymer layer so that the organic compound remains in the conductive polymer layer.

[0139] [Example]

[0140] Hereinafter, the present application will be described in further detail based on examples, but the present application is not limited to the examples. In these examples, a plurality of electrolytic capacitors were produced and evaluated using the following method.

[0141] (Capacitor A1)

[0142] First, prepare the anode foil, cathode foil, and separator containing a polymer layer. Aluminum foil with a roughened surface by etching is used for the anode foil. A dielectric layer (aluminum oxide layer) is formed on the surface of the aluminum foil by chemical conversion treatment. Aluminum foil is used for the cathode foil.

[0143] The polymer layer-containing spacer was prepared according to the following procedure. A spacer made of natural cellulose was used. The maximum peak volume Vs in the log differential pore volume distribution curve of the spacer alone was 2.9 cm 3 / g. A coating liquid containing a conductive polymer component was applied to the separator and then dried, thereby forming a conductive polymer layer within the separator. A separator containing a polymer layer was thus obtained. The coating liquid used was a dispersion of the conductive polymer component in water. The conductive polymer component used was poly(3,4-ethylenedioxythiophene) (PEDOT) doped with polystyrenesulfonic acid (PSS).

[0144] Then, the separator containing the polymer layer, the anode foil having the dielectric layer formed on its surface, and the cathode foil are wound to form a capacitor element. At this time, the components are wound so that the separator is disposed between the anode foil and the cathode foil.

[0145] Next, the capacitor element is immersed in a liquid (S) containing water and an organic compound (C) that does not boil at 100°C at 1 atmosphere, thereby allowing the liquid (S) to permeate the capacitor element. In this manner, the conductive polymer layer is impregnated with the liquid (S). Polyethylene glycol is used as the organic compound (C).

[0146] Then, the capacitor element was heated to remove water in the capacitor element so that the organic compound (C) remained in the conductive polymer layer. The heating was performed at a temperature of 135° C. for 20 minutes.

[0147] The capacitor element is then immersed in the liquid component (L) to allow the liquid component (L) to permeate the capacitor element (laminated body). The capacitor element is then heated. The anode foil of the capacitor element is then subjected to a chemical conversion treatment.

[0148] The laminated body having undergone the above steps was sealed in an outer package, thereby producing capacitor A1.

[0149] (Capacitors A2 to A4, C1 to C3)

[0150] Capacitors A2-A4 and C1-C3 were fabricated using the same conditions and methods as capacitor A1, except that the maximum peak volume Vmax of the polymer layer-containing separator was varied as shown in Table 1. The maximum peak volume Vmax was varied by varying the mass of the conductive polymer component contained in the separator. The same separator used in the fabrication of capacitor A1 was used.

[0151] (evaluate)

[0152] (1) Determination of maximum peak volume Vmax

[0153] The maximum peak volume Vmax of the separator having the conductive polymer layer formed thereon was measured by the following method. First, a sample having a size of approximately 100 mm × 10 mm (area: 10 cm 2 The sample was folded and placed in a measuring cell, where the pore distribution was determined using mercury intrusion porosimetry. The measurement was performed using an AutoPore V manufactured by Micromeritics. A log differential pore volume distribution curve was obtained from the measurement. The log differential pore volume of the maximum peak (maximum peak volume Vmax) was then determined from this distribution curve. Figure 4 9 shows the results of measuring the log differential pore volume distribution of an example of a polymer layer-containing separator used in an electrolytic capacitor (E).

[0154] (2) Measurement of the equivalent series resistance (ESR) of electrolytic capacitors

[0155] The ESR of the fabricated electrolytic capacitor was measured.

[0156] The evaluation results are shown in Table 1. In addition, the relationship between the maximum peak volume Vmax and ESR shown in Table 1 is shown in Figure 3 middle.

[0157] [Table 1]

[0158]

[0159] Capacitors A1 to A4 are electrolytic capacitors (E) manufactured using the manufacturing method (M). Capacitors C1 to C3 are comparative examples. Figure 3 As shown, by making the maximum peak volume Vmax between 1.0 and 2.3 cm 3The ESR of capacitors C1 to C3 whose maximum peak capacitance Vmax is not within this range is high.

[0160] Industrial applicability

[0161] This application can be used for electrolytic capacitors.

[0162] Description of Reference Numerals

[0163] 10 Capacitor element, 11 Anode foil, 12 Cathode foil, 13 Separator, 14 Winding and fixing tape, 100 Electrolytic capacitor, 101 Case with bottom, 102 Sealing member.

Claims

1. An electrolytic capacitor comprising a laminate and a liquid component impregnated into the laminate, The laminate includes an anode foil having a dielectric layer formed on its surface, a cathode foil, a separator, and a conductive polymer layer formed in the separator. The anode foil and the cathode foil are stacked with the separator interposed therebetween. In the log differential pore volume distribution curve of the separator having the conductive polymer layer formed thereon, the log differential pore volume of the maximum peak is at 1.0 cm 3 / g~2.3cm 3 / g range.

2. A method for manufacturing an electrolytic capacitor comprising an anode foil and a cathode foil having a dielectric layer formed on their surfaces, the method comprising: Step (i), forming a conductive polymer layer in the spacer using a coating liquid containing a conductive polymer component; Step (ii) of laminating the anode foil, the cathode foil, and the separator with the separator disposed between the anode foil and the cathode foil to form a laminate including the conductive polymer layer; as well as Step (iii), impregnating the layered product with a liquid component, In the step (i), the maximum peak of the log differential pore volume distribution curve of the separator having the conductive polymer layer formed thereon is located at 1.0 cm 3 / g~2.3cm 3 The conductive polymer layer is formed in a range of 1:1 / g.

3. The manufacturing method according to claim 2, wherein: Between the steps (ii) and (iii), the method further comprises: (x) impregnating the conductive polymer layer with a liquid containing water and an organic compound that does not boil at 100° C. under 1 atmosphere; and Step (y) of removing a portion of the liquid impregnated into the conductive polymer layer so that the organic compound remains in the conductive polymer layer.

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