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 on a surface thereof, a separator laminated on the anode foil, a cathode foil, and a conductive polymer layer formed on a surface of the dielectric layer and in a gap of the separator. The anode foil and the separator are bonded by the conductive polymer layer.

Description

Technical Field

[0001] This disclosure relates to electrolytic capacitors and methods for manufacturing electrolytic capacitors. Background Technology

[0002] Electrolytic capacitors are known as windings comprising an anode foil, a separator, and a cathode foil. One example of such an electrolytic capacitor includes a conductive polymer layer disposed within the winding. The conductive polymer layer can be formed by impregnating the winding with a dispersion containing conductive polymers. Various schemes have been proposed for electrolytic capacitors comprising a conductive polymer layer.

[0003] Claim 1 of Patent Document 1 (Japanese Patent No. 6911910) describes "an electrolytic capacitor, characterized in that a solid electrolyte layer is formed in a capacitor element formed by winding an anode electrode foil and a cathode electrode foil with a separator in between, the solid electrolyte layer using particles containing conductive polymers and a dispersion of conductive polymer compounds containing sorbitol or sorbitol and polyols, and containing 60 to 92 wt% of the sorbitol or sorbitol and polyols, and the voids in the capacitor element in which the solid electrolyte layer is formed are filled with an electrolyte containing 10 wt% or more ethylene glycol in the solvent."

[0004] Claim 1 of Patent Document 2 (Japanese Patent Publication No. 2019-516241) describes "a capacitor comprising a processed element, the processed element comprising: an anode having a dielectric on its surface and an anode conductive polymer layer on the surface of the dielectric; a cathode having a cathode conductive polymer layer; a conductive membrane between the anode and the cathode; an anode lead electrically in contact with the anode; and a cathode lead electrically in contact with the cathode."

[0005] Claim 1 of Patent Document 3 (International Publication No. 2021 / 125182) describes "a hybrid electrolytic capacitor, characterized in that it comprises a cathode, an anode, and a composite electrolyte layer, wherein the cathode has a cathode substrate made of a valve metal, an oxide layer disposed on the surface of the cathode substrate and made of an oxide of the valve metal, an inorganic conductive layer disposed on the surface of the oxide layer and comprising an inorganic conductive material, and an organic conductive layer disposed on the surface of the inorganic conductive layer and comprising a conductive polymer; the anode has an anode substrate made of a valve metal, and a dielectric layer disposed on the surface of the anode substrate and made of an oxide of the valve metal constituting the anode substrate; the composite electrolyte layer has a solid electrolyte layer disposed between and in contact with the organic conductive layer of the cathode and the dielectric layer of the anode and comprising particles of conductive polymer, and an electrolyte filling the particles of conductive polymer in the solid electrolyte layer."

[0006] Existing technical documents

[0007] Patent documents

[0008] Patent Document 1: Japanese Patent No. 6911910

[0009] Patent Document 2: Japanese Patent Publication No. 2019-516241

[0010] Patent Document 3: International Publication No. 2021 / 125182 Summary of the Invention

[0011] One aspect of this disclosure relates to an electrolytic capacitor comprising a laminate and a liquid component impregnated within the laminate. The laminate comprises an anode foil having a dielectric layer on its surface, a separator laminated thereon on the anode foil, a cathode foil, and a conductive polymer layer formed on the surface of the dielectric layer and within the voids of the separator. The anode foil and the separator are bonded together via the conductive polymer layer.

[0012] Another aspect of this disclosure relates to a method for manufacturing an electrolytic capacitor. The manufacturing method includes: a preparation step of preparing an anode foil having a dielectric layer on its surface; a laminate formation step of forming a laminate comprising the anode foil, a separator bonded to the anode foil, and a conductive polymer layer; a first laminate formation step of forming a first laminate comprising the anode foil, the separator, and the conductive polymer layer by cutting the laminate to a first width; and a second laminate formation step of forming a second laminate by laminating the first laminate with a cathode foil having a second width such that the separator is disposed between the anode foil and the cathode foil. The above-mentioned laminate formation process includes: a coating liquid application process, in which a coating liquid containing a conductive polymer and a liquid medium is applied to the surface of the dielectric layer and the voids of the separator while the anode foil and the separator are overlapped; and a liquid medium removal process, in which at least a portion of the liquid medium is removed from the coating liquid, thereby forming the conductive polymer layer on the surface of the dielectric layer and the voids of the separator, and the anode foil and the separator are bonded together, thereby forming the laminate.

[0013] According to this disclosure, it is possible to obtain an electrolytic capacitor containing liquid components and a conductive polymer layer with low ESR. Attached Figure Description

[0014] Figure 1 This is a side view schematically illustrating an example of an electrolytic capacitor according to an embodiment of the present disclosure.

[0015] Figure 2This is an exploded perspective view of a capacitor element schematically illustrating an example of an embodiment of the present disclosure.

[0016] Figure 3A This is a cross-sectional view of one step in a process that schematically illustrates an example of a method for forming the second layer (capacitor element).

[0017] Figure 3B It is a schematic representation of... Figure 3A A cross-sectional view of an example of a subsequent process.

[0018] Figure 3C It is a schematic representation of... Figure 3B A cross-sectional view of an example of a subsequent process.

[0019] Figure 4 A schematic representation of a device for measuring peel strength. Detailed Implementation

[0020] The following is a brief explanation of the problems in the existing technology.

[0021] Because dispersions containing conductive polymers have high viscosity, even when the dispersion penetrates the wound material, a sufficiently conductive polymer layer may not form inside the wound material. This inadequate formation of the conductive polymer layer can contribute to an increase in the equivalent series resistance (ESR).

[0022] Furthermore, when using a conductive polymer layer formed on the separator, improving the adhesion between the conductive polymer layer and the anode foil becomes important. If the adhesion between the conductive polymer layer and the anode foil is low, the ESR of the electrolytic capacitor becomes high, and the reliability of the electrolytic capacitor decreases.

[0023] The reduction of ESR in electrolytic capacitors has been a long-standing pursuit. This disclosure provides an electrolytic capacitor comprising a liquid component and a conductive polymer layer, which is capable of reducing ESR.

[0024] The following examples illustrate embodiments of the present invention, 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 materials can be applied as long as the invention disclosed herein can be implemented. In this specification, the phrase "numerical value A to numerical value B" includes both numerical value A and numerical value B, and can be replaced with "numerical value A or higher and numerical value B or lower." In the following description, when lower and upper limits of numerical values ​​related to specific physical properties, conditions, etc., are illustrated, any of the illustrated lower limits can be arbitrarily combined with any of the illustrated upper limits, as long as the lower limit is not higher than the upper limit.

[0025] (Manufacturing method of electrolytic capacitor)

[0026] Hereinafter, the manufacturing method of this embodiment will sometimes be referred to as "manufacturing method (M)". The manufacturing method (M) sequentially includes a preparation step, a laminate formation step, a first laminate formation step, and a second laminate formation step. Alternatively, an impregnation step may be included after the second laminate formation step. These steps will be described later.

[0027] In manufacturing a wound-type electrolytic capacitor having a conductive polymer layer disposed between the anode foil and the cathode foil, conventional methods involve impregnating the wound capacitor element with an aqueous dispersion of the conductive polymer. However, in this method, the amount of aqueous dispersion that can impregnate the wound is limited, making it difficult to form a sufficient amount of conductive polymer layer. On the other hand, in manufacturing method (M), since the conductive polymer layer is formed before forming the wound, a sufficient amount of conductive polymer layer can be easily formed. Furthermore, in manufacturing method (M), by forming the conductive polymer layer, the anode foil and the separator are tightly bonded to form a laminate. Then, the laminate and the cathode foil are used to form a wound. Therefore, misalignment between the anode foil and the separator is less likely to occur, and a highly reliable laminate can be easily manufactured.

[0028] (Preparation process)

[0029] The preparation process involves preparing an anode foil with a dielectric layer on its surface. The anode foil with the dielectric layer can be a commercially available product, or it can be formed by forming the dielectric layer on the surface of a metal foil (anode foil). The dielectric layer can be formed using known methods. For example, the dielectric layer can be formed by oxidizing the surface of the metal foil (anode foil).

[0030] (Laminated wafer formation process)

[0031] The laminate formation process is a process of forming a laminate comprising an anode foil, a separator bonded to the anode foil, and a conductive polymer layer. The laminate formation process includes a coating application process and a liquid dielectric removal process. The resulting laminate is cut to the width used in a capacitor element in a subsequent first laminate formation process. Therefore, the widths of the anode foil and separator used in the laminate formation process are greater than the widths of the anode foil and separator in the capacitor element. In the laminate formation process, the separator is bonded to at least one side of the anode foil, for example, it may be bonded to both sides of the anode foil. When the separator is bonded to both sides of the anode foil, the separator can be bonded to both sides of the anode foil simultaneously, or the separator can be bonded to one side of the anode foil and then another separator can be bonded to the other side.

[0032] The coating process involves applying a coating solution containing a conductive polymer and a liquid medium to the surface of the dielectric layer (the dielectric layer on the surface of the anode foil) and the voids of the separator while the anode foil and separator are overlapped. The liquid medium removal process involves removing at least a portion of the liquid medium from the coating solution, thereby forming a conductive polymer layer on the surface of the dielectric layer and in the voids of the separator, and then bonding the anode foil and separator together to form a laminate. Examples of conductive polymers will be described later.

[0033] There are no particular limitations on the liquid medium; any liquid medium suitable for forming a polymer layer can be used. Examples of liquid media include water, organic solvents (such as alcohols), and mixtures thereof. The coating solution can be a dispersion of conductive polymer particles dispersed in water.

[0034] The liquid medium may contain water and an organic compound that does not boil at 100°C under 1 atmosphere (101325 Pa). Hereinafter, this organic compound will sometimes be referred to as "organic compound (C)". Organic compound (C) can be a single compound or a combination of multiple compounds.

[0035] There is no limitation on the method of applying the coating liquid; it can be applied using known methods. For example, it can be done using a coating machine, by spraying the coating liquid, or by impregnating the object to be coated in the coating liquid. Examples of methods using a coating machine include gravure coating and die coating. In one example of gravure coating, firstly, the coating liquid is applied to a transfer member (such as a gravure roller), and then excess coating liquid is removed from the transfer member. Next, by transferring the coating liquid applied to the transfer member to a designated member (anode foil, cathode foil, or diaphragm), a layer of coating liquid of uniform thickness can be applied to that member. The viscosity of the coating liquid can be, for example, 10 mPa·s or more (e.g., 100 mPa·s or more) and 200 mPa·s or less. In this case, it is easy to apply the coating liquid to the anode foil, cathode foil, or diaphragm, and it is easy to impregnate the diaphragm with the coating liquid. It should be noted that the viscosity of the coating liquid is determined at room temperature (20°C) using a vibratory viscometer (e.g., SEKONIC, VM-100A). It should be noted that the method of applying the coating solution to the diaphragm includes a method of impregnating the diaphragm with the coating solution. The coating solution applied to the diaphragm penetrates into the interior of the diaphragm and reaches the dielectric layer on the surface of the anode foil. As a result, a conductive polymer layer is formed integrally on the surface of the dielectric layer and in the thickness direction of the diaphragm. By forming a conductive polymer layer, the adhesion between the anode foil (more specifically, the dielectric layer on the surface of the anode foil) and the diaphragm is significantly improved.

[0036] The method for removing at least a portion of the liquid medium from the coating liquid is not particularly limited and can be performed by heating, etc. When the coating liquid contains an organic compound (C), heating can be performed so that the organic compound (C) remains in the polymer layer. For example, when the coating liquid contains an organic compound (C) and water (liquid medium), by heating the coating liquid at a temperature above 100°C where the organic compound (C) does not boil or decompose, water can be removed from the coating liquid, while the organic compound (C) remains in the polymer layer. The heating temperature can be above 100°C, above 120°C, or above 140°C, or below 200°C or below 160°C. 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 sufficient to remove a portion of the liquid medium. An example heating time is in the range of 5 to 60 minutes.

[0037] By leaving organic compounds (C) in the conductive polymer layer, shrinkage of the conductive polymer layer during the removal of the liquid medium from the coating solution can be reduced. As a result, liquid components (e.g., electrolytes) can easily penetrate into the conductive polymer layer during subsequent impregnation processes. Consequently, the dielectric layer (oxide film) formation function of the liquid components can be fully utilized, and leakage current is reduced.

[0038] In a preferred example of the manufacturing method (M), the liquid medium of the coating solution is removed such that the water content in the coating solution is 40% by mass or more (e.g., 50% by mass or more), and the mass of the organic compound (C) in the conductive polymer layer is greater than the mass of the water in the conductive polymer layer. If the water content in the coating solution is high, the electrolyte can easily penetrate into the conductive polymer layer after it is formed.

[0039] (First layer of the stacked body formation process)

[0040] The first laminate forming process is a process of forming a first laminate comprising an anode foil, a separator, and a conductive polymer layer by cutting the laminate sheet to a first width. The width W0 of the laminate sheet can be more than twice the first width W1 of the first laminate. When the width W0 is more than twice the first width W1, multiple first laminates can be formed from the laminate sheet by cutting the laminate sheet. The method of cutting the laminate sheet is not limited, and known methods can be used. For example, a slitting machine used for cutting metal foil can be used to cut the laminate sheet. The width of the separator and the width of the anode foil are substantially the same as the first width W1 of the first laminate. In this specification, width refers to the length in a direction orthogonal to the length direction. In addition, the width of the components (first laminate and cathode foil) used in the formation of the winding body refers to the length in a direction parallel to the winding axis of the winding body.

[0041] The first width W1 is not limited and is selected according to the type and application of the electrolytic capacitor. The first width W1 can be 2.0mm or more, or 5.0mm or more, or less than 20mm or less than 12mm.

[0042] When cutting the laminate, the cut surface of the anode foil is exposed. Preferably, a dielectric layer is formed on the exposed surface after cutting through subsequent chemical conversion treatment or the like. In the first laminate, a diaphragm is attached to one or both sides of the anode foil.

[0043] (Second layer stacking process)

[0044] The second laminate formation process involves laminating a first laminate with a cathode foil having a second width by placing a diaphragm between the anode foil and the cathode foil. The width W2 of the cathode foil (the second width W2) can be smaller than the first width W1 of the first laminate. In this case, in the second laminate formation process, the first laminate and the cathode foil are laminated such that the end edge of the cathode foil in the width direction is positioned further inward than the end edge of the first laminate in the width direction. That is, the first laminate and the cathode foil are positioned such that the two end edges of the cathode foil in the width direction are located between the two end edges of the first laminate without contacting the two end edges of the first laminate. As a result, short circuits between the anode foil and the cathode foil can be suppressed.

[0045] There is no limitation on the method for forming the laminate; it can be formed by known methods. The laminate can be a wound body. In this case, during the laminate forming process, the anode foil, cathode foil, and diaphragm can be wound together by placing a diaphragm between the anode foil and the cathode foil to form a wound body. In the wound body, the anode foil, cathode foil, and diaphragm are stacked in the radial direction of the wound body.

[0046] A laminate can be formed by stacking a flat anode foil, a flat cathode foil, and a flat diaphragm in one direction. For example, multiple anode foils, multiple cathode foils, and multiple diaphragms can be stacked in one direction to form a laminate. In a typical example of this laminate, the anode foils and cathode foils are arranged alternately, and the diaphragm is disposed between the anode foils and cathode foils.

[0047] The difference (W1-W2) between the first width W1 of the first laminate and the second width W2 of the cathode foil can be 0.5 mm or more, or 1.0 mm or more, or 2.0 mm or less, 1.5 mm or less, or 1.2 mm or less. The difference (W1-W2) can be in the range of 0.5 mm to 1.2 mm. By setting the difference (W1-W2) to 0.5 mm or more, short circuits can be particularly suppressed. By setting the difference (W1-W2) to 1.0 mm or less, the decrease in electrostatic capacitance can be suppressed.

[0048] (Immersion process)

[0049] The manufacturing method (M) may further include an impregnation step after the second laminate formation step. The impregnation step is the process of impregnating a liquid component into the second laminate. Hereinafter, this liquid component is sometimes referred to as "liquid component (LC)". The method of impregnating the liquid component (LC) into the laminate is not limited. For example, the liquid component (LC) can be impregnated into the laminate by immersing at least a portion of the laminate in the liquid component (LC). The liquid component (LC) can be an electrolyte.

[0050] The liquid component (LC) may contain at least one selected from ethylene glycol, diethylene glycol, triethylene glycol, ethylene glycol condensates with a molecular weight of less than 250, glycerol, γ-butyrolactone, and sulfolane. By including these compounds in the liquid component (LC), the voltage withstand capability of the capacitor can be improved.

[0051] As described above, a capacitor element impregnated with a liquid component (LC) can be obtained. Then, other processes can be performed as needed. For example, a process of encapsulating the capacitor element impregnated with the liquid component (LC) into an outer casing can be performed.

[0052] The manufacturing method (M) may sequentially include a liquid application step and a removal step after the second laminate formation step and before the impregnation step. The liquid application step is the step of impregnating a liquid (hereinafter, sometimes referred to as "liquid (L)") into the laminate. The removal step is the step of removing at least a portion of the liquid (L) impregnated into the second laminate. The liquid (L) may be a liquid comprising water as a main component and an organic compound (C) that does not boil at 100°C under 1 atmosphere. In this case, the removal step may be a step of removing a portion of the aforementioned liquid impregnated into the laminate such that the mass of the organic compound (C) in the laminate is greater than the mass of the water in the laminate. Alternatively, the liquid (L) may be a liquid containing an organic solvent.

[0053] The liquid used in the liquid application process can be a liquid obtained by removing the conductive polymer components from the coating liquid used in the laminate formation process. The liquid impregnation in the liquid application process can be performed using a method exemplified for the coating liquid application process in the laminate formation process. The liquid removal in the removal process can be performed using a method exemplified for the liquid medium removal process in the laminate formation process. By performing the liquid application and removal processes, the adhesion between the conductive polymer layer and the cathode foil can be improved.

[0054] When the cathode foil is composed solely of metal foil (e.g., aluminum foil), an oxide layer forms on the surface of the metal foil, and the cathode foil also generates electrostatic capacitance. As a result, due to the combined capacitance of the anode foil and the cathode foil, the overall capacitance of the capacitor sometimes decreases. This problem can be suppressed by covering the surface of the metal foil with an inorganic layer, etc. That is, by forming an inorganic layer, only the capacitance of the anode foil can be drawn out. On the other hand, if the adhesion between the conductive polymer layer and the inorganic layer is low, the ESR becomes high. By performing the above-described liquid-applying process, the adhesion between the conductive polymer layer and the inorganic layer can be improved.

[0055] Inorganic layers tend to repel water. Therefore, in conventional methods that form conductive polymer layers by impregnating an aqueous dispersion of conductive polymers into a laminate (capacitor element), the conductive polymers have difficulty penetrating between the inorganic layer of the cathode foil and the anode foil within the laminate. Consequently, a uniform conductive polymer layer cannot be formed on the separator disposed between the cathode and anode foils, leading to an increase in ESR. In the manufacturing method (M), a separator with a pre-formed conductive polymer layer is used to form the laminate (capacitor element). Therefore, uneven distribution of conductive polymers within the separator can be suppressed.

[0056] The areal density of the conductive polymer layer can be 0.05 mg / cm³. 2 Above, 0.1 mg / cm 2 Above, or 0.3 mg / cm 2 The above can be 1.0 mg / cm³ 2 Below, or 0.5 mg / cm 2 For example, the areal density of the conductive polymer layer can be 0.05 mg / cm³. 2 Above and 1.0 mg / cm 2 The following describes how an electrolytic capacitor with exceptionally low ESR can be obtained based on this configuration. It should be noted that areal density refers to the mass per unit area. The areal density of the conductive polymer layer can be controlled by the concentration of the conductive polymer in the coating solution and the coating amount.

[0057] It should be noted that the areal density of the conductive polymer layer can be determined using the following method. First, five samples are prepared by cutting the anode foil and diaphragm before forming the laminate to a specified area, and the mass of these five samples is measured. Next, five samples are prepared by cutting the laminate with the conductive polymer layer formed to the aforementioned specified area, and the mass of these samples is measured. The areal density of the conductive polymer layer is determined by using the difference between the total mass of the five samples after the conductive polymer layer is formed and the total mass of the five samples before the conductive polymer layer is formed, along with the aforementioned specified area.

[0058] In an electrolytic capacitor manufactured by manufacturing method (M), the cathode foil may have an inorganic layer on its surface, and a conductive polymer layer may be bonded to the inorganic layer.

[0059] The peel strength between the anode foil and the diaphragm can be 1.0 N / cm or higher, 2.0 N / cm or higher, or 2.9 N / cm or higher. There is no particular upper limit to the peel strength. The peel strength can be measured using the methods described in the examples.

[0060] (Electrolytic capacitor)

[0061] Hereinafter, the electrolytic capacitor of this embodiment will sometimes be referred to as "electrolytic capacitor (E)". The electrolytic capacitor (E) can be manufactured using the manufacturing method (M) described above. The matters described in the manufacturing method (M) can be applied to the electrolytic capacitor (E), therefore repeated descriptions are sometimes omitted. The matters described in the electrolytic capacitor (E) can also be applied to the manufacturing method (M).

[0062] An electrolytic capacitor (E) comprises a laminate and a liquid component impregnated into the laminate. The laminate includes an anode foil having a dielectric layer on its surface, a separator laminated to the anode foil, a cathode foil, and a conductive polymer layer formed on the surface of the dielectric layer and within the voids of the separator. The anode foil and the separator are bonded together via the conductive polymer layer. The width of the cathode foil (second width W2) may be smaller than the width of the anode foil (first width W1). It should be noted that the width of the separator is substantially the same as the first width W1 of the anode foil.

[0063] According to the electrolytic capacitor (E), the effects described in the manufacturing method (M) can be obtained. For example, according to the configuration of the electrolytic capacitor (E), the ESR can be reduced.

[0064] In an electrolytic capacitor (E), the areal density of the conductive polymer layer can be within the aforementioned range. For example, the areal density of the conductive polymer layer can be 0.05 mg / cm³. 2 Above and 1.0 mg / cm 2 the following.

[0065] In an electrolytic capacitor (E), the cathode foil may have an inorganic layer on its surface. In this case, the conductive polymer layer is preferably bonded tightly to the inorganic layer.

[0066] As described above, the peel strength between the anode foil and the separator can be 1.0 N / cm or higher. As described above, the laminate can be a wound laminate or a laminate other than a wound laminate.

[0067] The following describes examples of materials and components used in the manufacturing method (M) and the electrolytic capacitor (E). However, the materials and components used in the manufacturing method (M) and the electrolytic capacitor (E) are not limited to the examples described below.

[0068] In this specification, the term "conductive polymer component" is sometimes used. When the conductive polymer is undoped, the conductive polymer component consists of the conductive polymer itself. When the conductive polymer is doped, the conductive polymer component consists of both the conductive polymer and the dopant.

[0069] (Applying liquid)

[0070] The coating solution used in the polymer layer formation process may contain conductive polymers and water. The conductive polymers (conductive polymer components) may be contained in the coating solution in the form of particles. The coating solution may be an aqueous dispersion of the conductive polymers (conductive polymer components).

[0071] The coating solution may contain other components (e.g., organic compound (C)). Organic compound (C) may contain at least one selected from polyols, sulfolane, γ-butyrolactone, and borate esters, or may be only one of these at least one. Organic compound (C) may contain at least one selected from glycols, glycerols, sugar alcohols, sulfolane, γ-butyrolactone, and borate esters, or may be only one of these at least one.

[0072] 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), and polyoxyethylene-polyoxypropylene glycol (ethylene oxide-propylene oxide copolymer). Examples of glycerols include glycerol and polyglycerol. Examples of sugar alcohols include mannitol, xylitol, sorbitol, erythritol, and pentaerythritol.

[0073] Examples of conductive polymers include polypyrrole, polythiophene, polyfuran, polyaniline, polyacetylene, and their derivatives. These derivatives include polymers with polypyrrole, polythiophene, polyfuran, polyaniline, and polyacetylene as their basic backbone. For example, derivatives of polythiophene include poly(3,4-ethylenedioxythiophene). These conductive polymers can be used alone or in combination. Furthermore, conductive polymers can also be copolymers of two or more monomers. The weight-average molecular weight of conductive polymers is not particularly limited, and can, for example, range from 1,000 to 100,000. A preferred example of a conductive polymer is poly(3,4-ethylenedioxythiophene) (PEDOT).

[0074] Conductive polymers can be doped with dopants. From the viewpoint of suppressing dedoping from conductive polymers, polymeric dopants are preferred as dopants. Examples of polymeric dopants include polyvinyl sulfonic acid, polystyrene sulfonic acid, polyallyl sulfonic acid, polypropylene sulfonic acid, polymethyl methacrylate sulfonic acid, poly(2-acrylamido-2-methylpropanesulfonic acid), polyisoprene sulfonic acid, polyacrylic acid, etc. They can be used alone or in combination of two or more. At least a portion of them can be added in the form of salts. A preferred example of a dopant is polystyrene sulfonic acid (PSS).

[0075] The dopant can be polystyrene sulfonic acid, and the conductive polymer can be poly(3,4-ethylenedioxythiophene). That is, the conductive polymer component can be poly(3,4-ethylenedioxythiophene) doped with polystyrene sulfonic acid.

[0076] When using conductive polymers doped with dopants, the pH of the coating solution is preferably less than 7.0, but can also be below 6.0 or 5.0, in order to suppress dopant dedoping. The pH of the coating solution can be above 1.0 or above 2.0.

[0077] The water content in the coating solution can be 40% or more by mass, 50% or more by mass, 80% or more by mass, 90% or more by mass, or 95% or more by mass. The water content can be less than 98% by mass, less than 95% by mass, less than 90% by mass, or less than 80% by mass.

[0078] The content of organic compound (C) in the coating solution can 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. It can be less than 30% by mass, less than 20% by mass, less than 15% by mass, or less than 10% by mass. The content of conductive polymer component in the coating solution can be 0.5% by mass or more, or 1.0% by mass or more, or less than 4.0% by mass, less than 3.0% by mass, or less than 2.0% by mass. This content can be in the range of 0.5% to 4.0% by mass or 1.0% to 4.0% by mass. Within any of these ranges, the upper limit can be set to 3.0% by mass or 2.0% by mass. From the perspective of excellent physical properties of the coating solution and its stability over time, and a good balance between the ESR of the electrolytic capacitor and cost, this content is preferably in the range of 1.0% to 3.0%. It should be noted that when the coating solution contains dopants, the mass of the dopants is included in the mass of the conductive polymer component.

[0079] There is no particular limitation on the mass of the dopant contained in the coating solution, and it can be in the range of 0.1 to 5 times (e.g., 0.5 to 3 times) the mass of the conductive polymer contained in the coating solution.

[0080] In the coating solution, the content of water: the content of organic compound (C): the content of conductive polymer component = 40~98: 1.0~59.5: 0.5~4.0, or the content of water: the content of organic compound (C): the content of conductive polymer component = 69.5~98: 1.0~30: 0.5~4.0.

[0081] (Liquid component (LC))

[0082] Examples of liquid components (LC) used in the impregnation process include non-aqueous solvents and electrolytes. The electrolyte may be a solution containing a non-aqueous solvent and a solute dissolved in the non-aqueous solvent. It should be noted that, in this specification, the liquid component (LC) 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.

[0083] The non-aqueous solvents used in liquid components (LC) can be organic solvents, ionic liquids, or protic solvents. Examples of non-aqueous solvents include polyols such as ethylene glycol and propylene glycol, 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, carbonates such as propylene carbonate, ethers such as 1,4-dioxane, ketones such as methyl ethyl ketone, and formaldehyde.

[0084] In addition, polymeric solvents can also be used as non-aqueous solvents. Examples of polymeric solvents include polyalkylene glycols, derivatives of polyalkylene glycols, and compounds in which at least one hydroxyl group in a polyol is replaced by a polyalkylene glycol (including its derivatives). Specifically, examples of polymeric 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, and polybutanediol. Examples of polymeric solvents also include copolymers of ethylene glycol and propylene glycol, copolymers of ethylene glycol and butanediol, and copolymers of propylene glycol and butanediol. One non-aqueous solvent can be used alone, or two or more can be used in combination.

[0085] Liquid components (LC) may contain non-aqueous solvents and base components (bases) dissolved in non-aqueous solvents. Alternatively, liquid components (LC) may also contain non-aqueous solvents and base and / or acid components (acids) dissolved in non-aqueous solvents.

[0086] As acid components, both polycarboxylic acids and monocarboxylic acids can be used. Examples of the aforementioned polycarboxylic acids include aliphatic polycarboxylic acids ([saturated polycarboxylic acids, such as oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, octanoic acid, azelaic acid, sebacic acid, 1,6-decanedicarboxylic acid, 5,6-decanedicarboxylic acid]; [unsaturated polycarboxylic acids, such as maleic acid, fumaric acid, itaconic acid]), aromatic polycarboxylic acids (such as phthalic acid, isophthalic acid, terephthalic acid, trimellitic acid, pyromellitic acid), and alicyclic polycarboxylic acids (such as cyclohexane-1,2-dicarboxylic acid, cyclohexene-1,2-dicarboxylic acid, etc.).

[0087] Examples of the aforementioned monocarboxylic acids include aliphatic monocarboxylic acids (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, behenic acid]; [unsaturated monocarboxylic acids, such as acrylic acid, methacrylic acid, oleic acid]), aromatic monocarboxylic acids (such as benzoic acid, cinnamic acid, naphtholic acid), and hydroxycarboxylic acids (such as salicylic acid, mandelic acid, resorcinol acid).

[0088] Among them, maleic acid, phthalic acid, benzoic acid, pyromellitic acid, and resorcinol are heat-stable and are preferred.

[0089] Inorganic acids can be used as the acid component. Representative examples of inorganic acids include phosphoric acid, phosphorous acid, hypophosphite, alkyl phosphates, boric acid, fluoroboric acid, tetrafluoroboric acid, hexafluorophosphate, benzenesulfonic acid, and naphthalenesulfonic acid. Alternatively, complex compounds of organic and inorganic acids can also be used as the acid component. Examples of such complex compounds include borodiethylene glycol acid, borodioxalic acid, and borodisalicylic acid.

[0090] The base component can be a compound with an alkyl-substituted amidine group, such as imidazole compounds, benzimidazole compounds, alicyclic amidine compounds (pyrimidine compounds, imidazoline compounds), etc. Specifically, 1,8-diazabicyclo[5,4,0]undec-7-ene, 1,5-diazabicyclo[4,3,0]non-5-ene, 1,2-dimethylimidazolineon, 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-methylimidazolium, and 1-methylbenzimidazole can be obtained. By using them, capacitors with excellent impedance performance can be obtained.

[0091] As a base component, quaternary salts of compounds having alkyl-substituted amidine groups can be used. Examples of such base components include imidazole compounds, benzimidazole compounds, and alicyclic amidine compounds (pyrimidine compounds, imidazole kinase compounds) that have been quaternized by alkyl or aryl alkyl groups having 1 to 11 carbon atoms. Specifically, 1-methyl-1,8-diazabicyclo[5,4,0]undec-7-ene, 1-methyl-1,5-diazabicyclo[4,3,0]non-5-ene, 1,2,3-trimethylimidazolinium, 1,2,3,4-tetramethylimidazolinium, 1,2-dimethyl-3-ethylimidazolinium, and 1,3,4-trimethyl-2-ethylimidazolinium are preferred. Imidazoline, 1,3-dimethyl-2-heptylimidazoline, 1,3-dimethyl-2-(3'-heptyl)imidazoline, 1,3-dimethyl-2-dodecylimidazoline, 1,2,3-trimethyl-1,4,5,6-tetrahydropyrimidine, 1,3-dimethylimidazoline, 1-methyl-3-ethylimidazoline, and 1,3-dimethylbenzimidazolium. By using these, capacitors with excellent impedance properties can be obtained.

[0092] Alternatively, tertiary amines can 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 from the perspective of increasing conductivity, and it is more preferable that they contain at least one selected from trimethylamine, dimethylethylamine, methyldiethylamine, and triethylamine. In addition, secondary amines such as dialkylamines, primary amines such as monoalkylamines, and ammonia can also be used as the base component.

[0093] Liquid components (LC) may contain salts of both acidic and basic components. The salts can be inorganic and / or organic. Organic salts are those in which at least one of the anion and cation contains an organic compound. Examples of organic salts include trimethylamine maleate, triethylamine borosalicylate, ethyldimethylamine phthalate, mono-1,2,3,4-tetramethylimidazoline phthalate, and mono-1,3-dimethyl-2-ethylimidazoline phthalate.

[0094] To suppress dopant dedoping, the pH of the liquid component (LC) can be set to less than 7.0 or below 5.0, or to above 1.0 or above 2.0. This pH can be set to above 1.0 and less than 7.0 (e.g., in the range of 2.0 to 5.0).

[0095] The liquid component (LC) preferably contains a protic solvent. By using a protic solvent, the conductive polymer layer can be particularly swollen. In addition to a protic solvent, the liquid component (LC) may also contain solvents other than protic solvents.

[0096] A protic solvent may contain at least one selected from glycols, glycerol, polyglycerol, and sugar alcohols, or it may consist of only one of these at least one compounds. A protic solvent may consist of only one compound or it may contain multiple compounds.

[0097] Organic compounds (C) and liquid components (LC) can contain the same compounds. For example, they can contain the same polyols, the same diols (ethylene glycol, etc.), and the same sugar alcohols.

[0098] (Liquid (L))

[0099] The liquid (L) may be a liquid containing the aforementioned organic compound (C) and water. In this case, it is preferable to remove water from the laminate after the liquid (L) has permeated into the laminate, while the organic compound (C) remains within the laminate. The organic compound (C) may be at least one selected from mannitol, mannitol derivatives, xylitol, and xylitol derivatives.

[0100] The liquid (L) may contain at least one selected from sugars, sugar alcohols, epoxy resins, and polyvinyl alcohol (hereinafter, sometimes referred to as "substance X"). By containing substance X in the liquid (L), the adhesion between the conductive polymer layer and the cathode foil can be improved. The content of substance X in the liquid (L) may be in the range of 10% by mass to 70% by mass (e.g., 30% by mass to 50% by mass).

[0101] The sugar alcohol may include at least one selected from mannitol, mannitol derivatives, xylitol, and xylitol derivatives, or may be only one of these at least one. Substance X may be at least one selected from mannitol, mannitol derivatives, xylitol, and xylitol derivatives. Mannitol, mannitol derivatives, xylitol, and xylitol derivatives have the effect of acting as an adhesive to tightly bond the conductive polymer layer to the cathode foil. Examples of xylitol derivatives include compounds in which a portion of the hydroxyl group of xylitol is esterified, compounds in which a portion of the hydroxyl group of xylitol is etherified, and compounds in which a portion of the hydroxyl group of xylitol is anionized to form a salt. Examples of mannitol derivatives include compounds in which a portion of the hydroxyl group of mannitol is esterified, compounds in which a portion of the hydroxyl group of mannitol is etherified, and compounds in which a portion of the hydroxyl group of mannitol is anionized to form a salt.

[0102] The organic solvent contained in the liquid (L) may contain at least one selected from ethylene glycol, diethylene glycol, triethylene glycol, and polyethylene glycol, or only one of these at least one. By containing these in the liquid (L), the adhesion between the conductive polymer layer and the cathode foil can be improved, and the ESR can be reduced.

[0103] A preferred example of a liquid (L) is a liquid containing xylitol in at least one organic solvent selected from triethylene glycol and polyethylene glycol.

[0104] (Anode foil)

[0105] Examples of anode foils include metal foils containing at least one valve metal such as titanium, tantalum, aluminum, and niobium, or metal foils containing a valve metal (e.g., aluminum foil). The anode foil may contain the valve metal in the form of an alloy 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.

[0106] A dielectric layer is formed on the surface of the anode foil. This dielectric layer can be formed by chemically converting the anode foil. In this case, the dielectric layer may contain an oxide of the valve metal (e.g., aluminum oxide). It should be noted that the dielectric layer can function as a dielectric, or it can be formed from a dielectric material other than an oxide of the valve metal.

[0107] In electrolytic capacitors, a conductive polymer layer may not be formed on the end face of the anode foil. On the other hand, it is preferable to form a dielectric layer on the end face of the anode foil.

[0108] (Cathode foil)

[0109] The cathode foil comprises a metal foil (e.g., aluminum foil). The metal constituting the metal foil can be a valve metal or an alloy containing a valve metal. The surface of the metal foil can be roughened by etching or the like. The thickness of the cathode foil can be 15 μm or more and 300 μm or less. A conductive polymer layer can be formed on the surface of the cathode foil. The conductive polymer layer can be formed by the same method as described in the above-described coating application step and liquid medium removal step.

[0110] As described above, the cathode foil can have an inorganic layer on its surface. The cathode foil with the inorganic layer can be a commercially available product, or it can be formed by forming an inorganic layer on the surface of a metal foil (cathode foil). The inorganic layer can be formed by known methods. For example, the inorganic layer can be formed by vacuum evaporation or the like. Alternatively, the inorganic layer can also be formed by coating a paste containing at least one of carbon (especially conductive carbon materials), titanium, and nickel onto the metal foil (cathode foil) and then drying it. The amount of inorganic layer can be 50 mg / m³. 2 ~300mg / m 2The range (e.g., 70 mg / m²) 2 ~200mg / m 2 (The scope is not specified). Examples of carbon (especially conductive carbon materials) contained in the inorganic layer include graphite, hard carbon, soft carbon, carbon black, etc. Additionally, when the inorganic layer contains titanium, it can be a layer deposited with titanium or a layer formed from titanium oxide particles. The inorganic layer can also be a carbon layer. A carbon layer is a layer containing carbon, and can be a layer with a carbon content of 50% by mass or more. In this specification, "inorganic layer" can be replaced with "carbon layer".

[0111] The cathode foil may comprise a metal foil, an inorganic layer, and a titanium-containing layer disposed between the inorganic layer and the metal foil. An example cathode foil has a laminated structure of inorganic layer / titanium-containing layer / metal foil (e.g., aluminum foil) / titanium-containing layer / inorganic layer. The titanium-containing layer may contain at least one material selected from titanium and titanium compounds. Examples of titanium compounds include titanium nitride, titanium oxide, titanium-aluminum alloys, titanium carbonate, etc. The method for forming the titanium-containing layer is not limited and can be formed by known methods. For example, the titanium-containing layer can be formed by physical vapor deposition methods such as vacuum evaporation or sputtering. The deposition amount of the titanium-containing layer can be 200 mg / m³. 2 ~500mg / m 2 The range (e.g., 250 mg / m²) 2 ~400mg / m 2 (the scope).

[0112] (Diaphragm)

[0113] The diaphragm can be made of porous sheet material. Examples of porous sheet materials include woven fabrics, nonwoven fabrics, and microporous membranes. The thickness of the diaphragm is not particularly limited and can range from 10 to 300 μm. Examples of diaphragm materials include cellulose, polyethylene terephthalate, polybutylene terephthalate, polyphenylene sulfide, vinylon, nylon, aromatic polyamides, polyimides, polyamide-imides, polyether-imides, rayon, and glass.

[0114] (outer body)

[0115] The laminate and liquid component (LC) are housed within an outer casing. The outer casing comprises a housing and / or a sealing resin. It is not limited to this; known housings and sealing resins may also be used. The sealing resin may comprise 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 contain fillers, curing agents, polymerization initiators, and / or catalysts, etc.

[0116] Hereinafter, an example of the present disclosure will be specifically described with reference to the accompanying drawings. The aforementioned constituent elements can be applied to the constituent elements of the example described below. Furthermore, the constituent elements of the example described below can be modified based on the above description. Additionally, the matters described below can be applied to the embodiments described above. Furthermore, in one example described below, constituent elements that are not essential to the electrolytic capacitor of the present disclosure can be omitted.

[0117] Figure 1 This is a schematic cross-sectional view of an electrolytic capacitor 100, illustrating an example of this embodiment. Figure 2 This is a schematic diagram obtained by unfolding a portion of the capacitor element 10 contained in the electrolytic capacitor 100.

[0118] The electrolytic capacitor 100 includes a capacitor element 10, a bottom housing 101 for housing the capacitor element 10, a sealing member 102 that blocks the opening of the bottom housing 101, a base plate 103 covering the sealing member 102, leads 104A and 104B extending from the sealing member 102 and through the base plate 103, and lead connectors 105A and 105B connecting the leads to the electrodes of the capacitor element 10. The bottom housing 101 is drawn inward near the opening end, and the opening end is rolled in a manner that tightens it against the sealing member 102.

[0119] Capacitor element 10 is, for example, as Figure 1 The wound body is shown. The wound body includes an anode foil connected to lead connector 105A, a cathode foil 12 connected to lead connector 105B, and a separator 13. The capacitor element 10 (wound body) includes a conductive polymer layer (not shown). The conductive polymer layer may contain an organic compound (C). The electrolytic capacitor 100 includes a liquid component (LC) (e.g., electrolyte) impregnated into the capacitor element 10.

[0120] The capacitor element 10 is formed by winding a strip-shaped first laminate 11y having a first width W1 with a strip-shaped cathode foil 12 having a second width W2. The first laminate 11y includes an anode foil, a separator attached to the anode foil, and a conductive polymer layer. The first laminate 11y and the cathode foil 12 are wound such that a separator 13 is disposed between the anode foil and the cathode foil 12. The outermost periphery of the wound is fixed by a winding fixing tape 14. It should be noted that... Figure 2 This indicates the unfolded state of a portion of the fixed winding before its outermost circumference.

[0121] An electrolytic capacitor may have at least one capacitor element or multiple capacitor elements. The number of capacitor elements in an electrolytic capacitor is determined by its intended use.

[0122] exist Figures 3A-3CThe cross-sectional view schematically illustrates an example of a method for forming the second layer (capacitor element). First, as... Figure 3A As shown, the anode foil 11a is overlapped with the diaphragm 13a. It should be noted that a dielectric layer (not shown) is formed on both sides of the anode foil 11a. Next, the above-described coating application process and liquid medium removal process are performed to form... Figure 3B The laminate 11x shown comprises an anode foil 11a and a separator 13b in which a conductive polymer layer is formed within the voids. The conductive polymer layer is integrally formed on the surface of the dielectric layer and within the voids of the separator. As a result, the anode foil 11a is bonded to the separator 13b. Furthermore, by similarly performing the above-described coating process and liquid medium removal process on the surface opposite to the surface of the anode foil 11a to which the separator 13b is bonded, the anode foil 11a is bonded to the separator 13b.

[0123] Next, as Figure 3C As shown, a laminate 11x with a separator 13b bonded to both sides of the anode foil 11a is cut to a first width W1, thereby forming a first laminate 11y comprising the anode foil 11, a conductive polymer layer, and a separator 13 (13b). Next, a second laminate can be obtained by laminating the first laminate 11y with a cathode foil 12 having a second width W2. For example, as... Figure 2 As shown, the first layer 11y is wound with the cathode foil 12.

[0124] (Postscript)

[0125] The following technologies are disclosed through the above description.

[0126] (Technology 1)

[0127] An electrolytic capacitor comprises a laminate and a liquid component impregnated in the laminate.

[0128] The above-mentioned stacked body includes:

[0129] Anode foil with a dielectric layer on its surface;

[0130] A diaphragm laminated on the aforementioned anode foil;

[0131] cathode foil; and

[0132] A conductive polymer layer formed on the surface of the dielectric layer and within the pores of the diaphragm.

[0133] The anode foil and the diaphragm are bonded together through the conductive polymer layer.

[0134] (Technology 2)

[0135] According to the electrolytic capacitor described in Technique 1, the width of the cathode foil is smaller than the width of the anode foil.

[0136] (Technology 3)

[0137] According to the electrolytic capacitor described in technique 1 or 2, the areal density of the aforementioned conductive polymer layer is 0.05 mg / cm³. 2 Above and 1.0 mg / cm 2 the following.

[0138] (Technology 4)

[0139] According to any one of the techniques 1 to 3, the electrolytic capacitor wherein the cathode foil has an inorganic layer on its surface.

[0140] The aforementioned conductive polymer layer is tightly bonded to the aforementioned inorganic layer.

[0141] (Technology 5)

[0142] According to any one of the techniques 1 to 4, the peel strength between the anode foil and the separator is 1.0 N / cm or more.

[0143] (Technology 6)

[0144] According to any one of the techniques 1 to 5, the width of the anode foil is the same as the width of the diaphragm.

[0145] (Technology 7)

[0146] An electrolytic capacitor according to any one of techniques 1 to 6, wherein the aforementioned laminated body is a wound body.

[0147] (Technology 8)

[0148] A method for manufacturing an electrolytic capacitor, comprising:

[0149] Preparation process: Prepare an anode foil with a dielectric layer on its surface;

[0150] The laminate forming process forms a laminate comprising the aforementioned anode foil, a diaphragm bonded to the aforementioned anode foil, and a conductive polymer layer;

[0151] The first laminate formation process involves cutting the laminated sheet to a first width to form a first laminate comprising the anode foil, the diaphragm, and the conductive polymer layer; and

[0152] The second laminate formation process involves laminating the first laminate with a cathode foil having a second width by placing the diaphragm between the anode foil and the cathode foil, thereby forming the second laminate.

[0153] The above-mentioned laminated wafer forming process includes:

[0154] The coating process involves applying a coating containing a conductive polymer and a liquid medium to the surface of the dielectric layer and the voids of the separator while the anode foil and the separator are overlapped; and

[0155] The liquid medium removal process involves removing at least a portion of the liquid medium from the coating liquid, thereby forming the conductive polymer layer on the surface of the dielectric layer and within the voids of the diaphragm, and then bonding the anode foil to the diaphragm to form the laminate.

[0156] (Technology 9)

[0157] According to the manufacturing method of the electrolytic capacitor described in Technique 8, the second width of the cathode foil is smaller than the first width of the first laminate.

[0158] (Technology 10)

[0159] According to the manufacturing method of the electrolytic capacitor described in Technique 8 or 9, the areal density of the aforementioned conductive polymer layer is 0.05 mg / cm³. 2 Above and 1.0 mg / cm 2 the following.

[0160] (Technology 11)

[0161] According to any one of the methods for manufacturing an electrolytic capacitor described in art 8 to 10, the cathode foil has an inorganic layer on its surface.

[0162] The aforementioned conductive polymer layer is tightly bonded to the aforementioned inorganic layer.

[0163] (Technology 12)

[0164] According to any one of the methods for manufacturing an electrolytic capacitor described in art 8 to 11, the peel strength between the anode foil and the separator is 1.0 N / cm or more.

[0165] (Technology 13)

[0166] According to any one of the methods for manufacturing an electrolytic capacitor described in Artificial Intelligence 8 to 12, the second layer is a wound layer.

[0167] Example

[0168] The present disclosure will now be described in more detail based on embodiments, but the disclosure is not limited to these embodiments. In this embodiment, a plurality of electrolytic capacitors are fabricated and evaluated using the following method.

[0169] (Capacitor A1)

[0170] An electrolytic capacitor (capacitor A1) is made using the following method.

[0171] (a) Preparation of constituent components

[0172] An aluminum foil (thickness: 100 μm) is etched to roughen its surface. The roughened surface is then chemically converted to form a dielectric layer. This yields an anode foil with dielectric layers on both sides. Carbon layers are then formed on both sides of an aluminum foil (thickness: 50 μm) that becomes the cathode foil. These carbon layers are formed using a vacuum evaporation method.

[0173] As a diaphragm, a nonwoven fabric (50 μm thick) is prepared. The nonwoven fabric used is a nonwoven fabric composed of polyester fiber, aramid fiber and cellulose.

[0174] (b) Formation of laminated sheets

[0175] As a coating solution, a dispersion (commercially available product) is prepared by dispersing polyvinyl sulfonic acid (PSS)-doped polyethylene dioxythiophene (PEDOT) particles in water.

[0176] Next, with the anode foil and separator overlapped, a coating solution is applied to the separator, thereby imparting the coating solution to the surface of the dielectric layer of the anode foil and the voids of the separator. Next, the anode foil and separator coated with the coating solution are heated at 125°C for 5 minutes, thereby removing the liquid dielectric from the applied coating solution. This heating forms a conductive polymer layer on the surface of the dielectric layer and within the voids of the separator, and the anode foil and separator are then bonded together. In this embodiment, the separator is bonded to both sides of the anode foil. This results in a laminated sheet.

[0177] (c) Formation of the first and second layers

[0178] Next, a first laminate with a first width W1 (10 mm) is formed by cutting the laminated sheet. Then, the first laminate and a cathode foil with a second width W2 (9 mm) are wound together with a diaphragm positioned between the anode and cathode foils, thereby forming a wound body (second laminate). At this time, the ends of the outer surface of the wound body are secured with a winding fixing tape. It should be noted that before forming the wound body, an anode lead connector is connected to the anode foil, and a cathode lead connector is connected to the cathode foil.

[0179] Next, anode and cathode leads are connected to the ends of the lead connectors protruding from the winding body. The resulting winding body is then subjected to another chemical conversion treatment to form a dielectric layer on the end face of the anode foil. This yields a capacitor element.

[0180] (d) Infiltration of liquid components

[0181] An electrolyte (liquid component) is prepared by dissolving phthalic acid and triethylamine (base component) in ethylene glycol (solvent) at a combined concentration of 25% by mass. The capacitor element is then immersed in the electrolyte for 5 minutes under reduced pressure (40 kPa). This allows the electrolyte to permeate the capacitor element (laminated structure).

[0182] (e) Sealing of capacitor elements

[0183] The capacitor element impregnated with electrolyte is sealed to manufacture such a process. Figure 1 The electrolytic capacitor shown was then aged at 95°C for 90 minutes while a voltage was applied. This produced the electrolytic capacitor (capacitor A1).

[0184] (Capacitor C1)

[0185] Except for the differences in the formation methods of the conductive polymer layer and the winding body, the electrolytic capacitor (capacitor C1) is manufactured using the same methods and conditions as capacitor A1. The conductive polymer layer formed on the dielectric layer on the surface of the anode foil is formed by applying the coating solution used in capacitor A1 onto the dielectric layer and then drying it. The conductive polymer layer formed within the pores of the separator is formed by applying the coating solution used in capacitor A1 onto the separator and then drying it. That is, in the manufacture of capacitor C1, the conductive polymer layer on the dielectric layer and the conductive polymer layer within the separator are formed separately, and the anode foil and separator are not bonded together.

[0186] The wound body is formed by winding an anode foil with a conductive polymer layer, a cathode foil with a conductive polymer layer, and a separator, with a separator disposed between the anode foil and the cathode foil. The dimensions of these components are set to be the same as those of the components used in capacitor A1. After the wound body is made, capacitor C1 is made using the same methods and conditions as capacitor A1.

[0187] (evaluate)

[0188] The equivalent series resistance (ESR) of the fabricated electrolytic capacitor was measured. Furthermore, the fabricated electrolytic capacitor was disassembled, and the peel strength between the anode foil (more specifically, the dielectric layer on the surface of the anode foil) and the separator was measured using the following method.

[0189] (1) Determination of peel strength

[0190] In this embodiment, firstly, the electrolytic capacitor is disassembled and the winding body (capacitor element 10) is removed. Next, the anode foil 11 is pulled from the outer periphery of the winding body, and a portion of the anode foil 11 is peeled off from the winding body, so that the diaphragm 13 that is sealed to the anode foil 11 is separated from the anode foil 11.

[0191] A summary of the composition of the measuring device 20 used in the peel strength determination is shown below. Figure 4 The testing apparatus is preferably of a specification capable of performing tests according to JIS C0806-3:2014. The testing apparatus 20 includes a feed sheet 21, a feed roller 22, and a recovery device 23. The outer peripheral surface of the peeled anode foil 11 is fixed to the feed sheet 21 by a fixing clamp 24. The feed sheet 21 is fed in a first direction by the feed roller 22. The recovery device 23 recovers the cathode foil 12 and diaphragm 13, from which the anode foil 11 has been peeled, in a second direction opposite to the first direction. The recovery device 23 has a winding roller for winding the cathode foil 12 and diaphragm 13. The conveying speed of the anode foil 11 based on the feed roller 22 and the winding speed of the cathode foil 12 and diaphragm 13 based on the recovery device 23 are controlled so that the position of the capacitor element 10 does not move during the test.

[0192] The anode foil 11 to be peeled off is fixed to the feed sheet, and the cathode foil 12 and diaphragm 13 with the anode foil 11 peeled off are placed in the recycling device 23. The measuring device uses a high-speed peel strength tester (PTS-5000K) for embossed tape manufactured by EPI Corporation.

[0193] In this embodiment, the anode foil 11, cathode foil 12, and diaphragm 13 are pulled in the measuring device 20 such that the angle between the direction in which the anode foil 11, fixed to the feed sheet 21, is pulled and the direction in which the cathode foil 12 and diaphragm 13 are pulled by the recovery device 23 is approximately 175°. At this time, the anode foil 11 and diaphragm 13 are pulled for 60 seconds, causing the anode foil 11 and diaphragm 13 to peel off continuously at a certain speed (160 mm / min). Then, the force pulling the cathode foil 12 at this time is measured at sampling intervals of 0.01 seconds. The average value of the measured force pulling the cathode foil 12 is then taken as the peel strength.

[0194] The evaluation results are shown in Table 1.

[0195]

[0196] Capacitor A1 is an electrolytic capacitor (E) of this disclosure manufactured by manufacturing method (M). Capacitor C1 is a comparative example. As shown in Table 1, capacitor A1 has high peel strength between the anode foil and the separator and low ESR.

[0197] Industrial availability

[0198] This disclosure can be used for electrolytic capacitors.

[0199] Explanation of reference numerals in the attached figures

[0200] 10: Capacitor element (second layer)

[0201] 11: Anode foil

[0202] 11a: Anode foil

[0203] 11x: Stacked wafers

[0204] 11y: First layer of stacked body

[0205] 12: Cathode foil

[0206] 13, 13a, 13b: Diaphragm

[0207] 100: Electrolytic capacitor

Claims

1. An electrolytic capacitor comprising a laminate and a liquid component impregnated into the laminate, the laminate comprising: an anode foil having a dielectric layer on a surface thereof; a separator laminated to the anode foil; a cathode foil; and a conductive polymer layer formed in a space of the separator and on a surface of the dielectric layer, the anode foil and the separator being attached via the conductive polymer layer.

2. The electrolytic capacitor of claim 1, wherein, The cathode foil has a width smaller than that of the anode foil.

3. The electrolytic capacitor of claim 1, wherein, The surface density of the conductive polymer layer is 0.05 mg / cm 2 The surface density of the conductive polymer layer is 0.05 mg / cm 2 The surface density of the conductive polymer layer is 0.05 mg / cm 4. The electrolytic capacitor of claim 1, wherein, The cathode foil has an inorganic layer on a surface thereof, the conductive polymer layer and the inorganic layer being attached to each other.

5. The electrolytic capacitor of claim 1, wherein, A peeling strength between the anode foil and the separator is 1.0 N / cm or more.

6. The electrolytic capacitor of claim 1, wherein, The anode foil has a width identical to that of the separator.

7. The electrolytic capacitor of claim 1, wherein, The laminate is a wound body.

8. A method of manufacturing an electrolytic capacitor, comprising: a preparation step of preparing an anode foil having a dielectric layer on a surface thereof; a laminate sheet forming step of forming a laminate sheet comprising the anode foil, a separator attached to the anode foil, and a conductive polymer layer; a first laminate forming step of forming a first laminate comprising the anode foil, the separator, and the conductive polymer layer by cutting the laminate sheet into a first width; and a second laminate forming step of forming a second laminate by laminating the first laminate with a cathode foil having a second width in a manner that the separator is disposed between the anode foil and the cathode foil, the laminate sheet forming step comprising: a coating liquid imparting step of imparting a coating liquid containing a conductive polymer and a liquid medium to a surface of the dielectric layer and a space of the separator in a state that the anode foil and the separator are overlapped; and a liquid medium removing step of forming the conductive polymer layer in the surface of the dielectric layer and the space of the separator by removing at least a part of the liquid medium from the coating liquid, and attaching the anode foil and the separator, thereby forming the laminate sheet. The second width of the cathode foil is smaller than the first width of the first laminate. The cathode foil has an inorganic layer on a surface thereof, 9. The method of manufacturing an electrolytic capacitor according to claim 8, wherein, the conductive polymer layer and the inorganic layer being attached to each other.

10. The method of manufacturing an electrolytic capacitor according to claim 8, wherein, The surface density of the conductive polymer layer is 0.05 mg / cm 2 The surface density of the conductive polymer layer is 0.05 mg / cm 2 The surface density of the conductive polymer layer is 0.05 mg / cm 11. The method of manufacturing an electrolytic capacitor as claimed in claim 8, wherein, A peeling strength between the anode foil and the separator is 1.0 N / cm or more. The second laminate is a wound body.

12. The method of manufacturing an electrolytic capacitor as claimed in claim 8, wherein, ​ 13. The method of manufacturing an electrolytic capacitor as claimed in claim 8, wherein, ​

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