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 the surface thereof, a cathode foil having an inorganic layer on the surface thereof, a separator, and a first conductive polymer layer held by the separator. The first conductive polymer layer contains a first conductive polymer. The proportion of the area of the first conductive polymer layer in the area of the surface of the separator is 80% or more. The first conductive polymer layer held by the separator is in close contact with the inorganic 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 Application Publication No. 2022-144278) describes "a solid electrolytic capacitor, characterized in that it comprises: a capacitor element formed by placing an anode foil and a cathode body opposite each other, a conductive polymer layer formed by impregnating a dispersion containing particles or powder of a conductive polymer and a solvent, and an electrolyte impregnated in the capacitor element, wherein the cathode body has a cathode foil and a carbon layer, the cathode foil is made of a valve metal and has an extended surface layer formed on its surface, the carbon layer is stacked on the extended surface layer and contacts the conductive polymer layer on the side opposite to the extended surface layer, and the amount of conductive polymer particles or powder contained in the extended surface layer is less than the amount of conductive polymer particles or powder contained in the surface side of the carbon layer facing the conductive polymer layer."

[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 Application Publication No. 2022-144278

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

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

[0011] The problem that the invention aims to solve

[0012] 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 cathode foil having an inorganic layer on its surface, a separator, and a first conductive polymer layer retained in the separator. The first conductive polymer layer contains a first conductive polymer, and the area of ​​the first conductive polymer layer accounts for more than 80% of the surface area of ​​the separator. The first conductive polymer layer retained in the separator is in close contact with the inorganic layer.

[0013] 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 and a cathode foil having an inorganic layer on its surface; a first polymer layer forming step of forming a first conductive polymer layer within the voids of a separator; a laminate forming step of forming a laminate comprising the anode foil, the cathode foil, and the separator disposed between the anode foil and the cathode foil; and a sealing step of sealing the first conductive polymer layer to the inorganic layer by impregnating the laminate with a liquid containing an organic solvent. The first polymer layer forming step includes: a first coating liquid application step of applying a first coating liquid containing the first conductive polymer and a first liquid medium to the voids of the separator; and a first liquid medium removal step of removing at least a portion of the first liquid medium from the first coating liquid, thereby forming the first conductive polymer layer within the voids of the separator.

[0014] According to this disclosure, it is possible to obtain an electrolytic capacitor containing liquid components and a conductive polymer layer with low equivalent series resistance (ESR). Attached Figure Description

[0015] Figure 1 This is a side view schematically illustrating an example of an electrolytic capacitor according to an embodiment of the present disclosure.

[0016] Figure 2 This is an exploded perspective view of a capacitor element schematically illustrating an example of an embodiment of the present disclosure.

[0017] Figure 3 An example of a device for measuring peel strength is shown schematically. Detailed Implementation

[0018] The following is a brief explanation of the problems in the existing technology.

[0019] 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).

[0020] Furthermore, when using a conductive polymer layer formed on the diaphragm, it becomes important to reduce the resistance between the conductive polymer layer and the cathode. If the resistance between the conductive polymer layer and the cathode foil is high, the ESR increases.

[0021] 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.

[0022] 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.

[0023] (Manufacturing method of electrolytic capacitor)

[0024] Hereinafter, the manufacturing method of this embodiment will sometimes be referred to as "manufacturing method (M)". Manufacturing method (M) includes a preparation step, a polymer layer forming step (first polymer layer forming step), a laminate forming step, and a bonding step. The polymer layer forming step, the laminate forming step, and the bonding step are performed sequentially. The preparation step is performed before the laminate forming step. The preparation step may be performed before the polymer layer forming step. Alternatively, a cathode foil with an inorganic layer on its surface may be prepared after the polymer layer forming step. Furthermore, an impregnation step may be included after the bonding step. Each step will be described below.

[0025] (Preparation process)

[0026] The preparation process involves preparing an anode foil having a dielectric layer on its surface and a cathode foil having an inorganic layer on its surface. The inorganic layer is a layer containing at least one of carbon, titanium, and nickel, and may be a layer composed of at least one of these materials.

[0027] Anode foil with a dielectric layer on its surface can be commercially available or formed by forming a dielectric layer on the surface of a metal foil (anode foil). Cathode foil with an inorganic layer on its surface can be commercially available or formed by forming an inorganic layer on the surface of a metal foil (cathode foil). The dielectric layer and inorganic layer can be formed by known methods. For example, the dielectric layer can be formed by oxidizing the surface of the metal foil (anode foil). The inorganic layer can be formed by vacuum evaporation or similar methods. Alternatively, the inorganic layer can be formed by coating a paste containing 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 2 The range (e.g., 70 mg / m²) 2 ~200mg / m 2(The scope is not specified). Examples of conductive carbon materials contained in the inorganic layer include graphite, hard carbon, soft carbon, carbon black, etc. Additionally, the inorganic layer can be a layer formed by vapor deposition of titanium or a layer formed using titanium oxide particles. Furthermore, the inorganic layer can be a layer formed by vapor deposition of nickel. 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" may be replaced with "carbon layer".

[0028] 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).

[0029] (Polymer layer formation process)

[0030] The polymer layer forming process includes a first polymer layer forming process that forms a first conductive polymer layer within the voids of the diaphragm. The polymer layer forming process may further include a second polymer layer forming process that forms a second conductive polymer layer on the surface of the dielectric layer (the dielectric layer formed on the surface of the anode foil). The first and second polymer layer forming processes can be performed either first or simultaneously.

[0031] The first polymer layer formation process includes: a first coating solution application process, which applies a first coating solution containing a first conductive polymer and a first liquid medium into the voids of the diaphragm; and a first liquid medium removal process, which forms a first conductive polymer layer into the voids of the diaphragm by removing at least a portion of the first liquid medium from the first coating solution. The second polymer layer formation process includes: a second coating solution application process, which applies a second coating solution containing a second conductive polymer and a second liquid medium to the surface of a dielectric layer (a dielectric layer formed on the surface of the anode foil); and a second liquid medium removal process, which forms a second conductive polymer layer on the surface of the dielectric layer by removing at least a portion of the second liquid medium from the second coating solution. The second conductive polymer layer is typically formed on both sides of the anode foil.

[0032] The first and second conductive polymers can be the same or different. They can each be contained in the coating solution as particles. Examples of conductive polymers will be described later.

[0033] The liquid medium is not particularly limited; any liquid medium suitable for forming the polymer layer can be used. Examples of liquid media include water, organic solvents (e.g., alcohols), and mixtures thereof. The first coating solution and / or the second coating solution can be a dispersion of conductive polymer particles dispersed in water.

[0034] The first liquid medium and / or the second 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) may be a single compound or may consist of multiple compounds.

[0035] The method of applying the coating liquid is not limited and can be achieved 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 adhered to a transfer member (gravure roller, etc.), and excess coating liquid is removed from the transfer member. Next, by transferring the coating liquid adhered to the transfer member to a designated member (anode foil, cathode foil, or diaphragm), a layer of coating liquid of uniform thickness can be adhered to that member. It should be noted that the method of applying the coating liquid to the diaphragm includes the method of impregnating the diaphragm with the coating liquid. The coating liquid applied to the diaphragm penetrates into the interior of the diaphragm, and a conductive polymer layer can be formed integrally in the thickness direction of the diaphragm. The viscosity of the coating liquid can, for example, be 10 mPa·s or more (e.g., 100 mPa·s or more) and 200 mPa·s or less. In this case, the coating solution is easily applied to the anode foil, cathode foil, and diaphragm, and easily penetrates the diaphragm. It should be noted that the viscosity of the coating solution is determined at room temperature (20°C) using a vibratory viscometer (e.g., SEKONIC, VM-100A).

[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, in subsequent sealing and impregnation processes, liquids containing organic solvents and liquid components (e.g., electrolytes) can easily penetrate into the conductive polymer layer. Consequently, in the sealing process, the adhesion between the first conductive polymer layer and the inorganic layer, as well as between the first and second conductive polymer layers, can be improved. Furthermore, the dielectric layer (oxide film) formation function of the liquid component is more readily utilized, reducing leakage current.

[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] In the first polymer layer formation step of the manufacturing method (M), the first conductive polymer layer is preferably formed such that the proportion of the area of ​​the first conductive polymer layer to the surface of the separator (hereinafter, sometimes referred to as "proportion R") is 80% or more. By setting the proportion R to 80% or more, ESR can be particularly reduced. Furthermore, by setting the proportion R to 80% or more, the adhesion between the first conductive polymer layer and the inorganic layer of the cathode foil can be particularly improved. The proportion R is preferably set to 90% or more, more preferably 95% or more, and particularly preferably 98% or more. By increasing the proportion R, ESR can be further reduced.

[0040] The ratio R is the ratio of the area of ​​the first conductive polymer layer occupying the surface of the membrane to the area of ​​the membrane, determined based on the membrane's dimensions. The ratio R can be obtained by acquiring an image of the surface of the membrane on which the first conductive polymer layer is formed and performing image processing on that image. Typically, the color of the first conductive polymer layer differs from the color of the membrane; therefore, by binarizing the image of the surface of the membrane on which the first conductive polymer layer is formed, the area of ​​the region on which the first conductive polymer layer is formed can be determined. Then, the ratio R can be calculated based on the area Sp of the region on which the first conductive polymer layer is formed and the area Ss of the membrane. It should be noted that the ratio R is calculated using the following formula.

[0041] R (%) = (Sp / Ss) × 100

[0042] The areal density of the first 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 5.0 mg / cm³ 2 Below, 1.0 mg / cm 2 Below, or 0.5 mg / cm 2 For example, the areal density of the first conductive polymer layer can be 0.05 mg / cm³. 2 Above and 1.0 mg / cm 2 The following describes how this configuration allows for the production of electrolytic capacitors with exceptionally low ESR. It should be noted that areal density refers to the mass per unit area.

[0043] The areal density of the second 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 5.0 mg / cm³ 2 Below, 1.0 mg / cm 2 Below, or 0.5 mg / cm 2 The following refers to the areal density of a second conductive polymer layer formed on both sides of the anode foil, where the second conductive polymer layer is formed on one side of the anode foil.

[0044] It should be noted that the areal density of the first conductive polymer layer can be determined using the following method. First, five samples are prepared by cutting the membrane before the formation of the first conductive polymer layer to a specified area, and the mass of these five samples is measured. Next, five samples are prepared by cutting the membrane with the first conductive polymer layer formed to the aforementioned specified area, and the mass of these samples is measured. The areal density of the first conductive polymer layer is determined using the difference between the total mass of the five samples after the formation of the first conductive polymer layer and the total mass of the five samples before the formation of the first conductive polymer layer, and the aforementioned specified area.

[0045] The ratio R can be varied by adjusting the viscosity of the coating liquid when applying the conductive polymer-containing liquid using a coating machine or similar device. Furthermore, the areal density of the conductive polymer layer can be controlled by the viscosity of the coating liquid. Alternatively, the areal density of the conductive polymer can be controlled by the concentration of the conductive polymer in the coating liquid and the coating amount. It should be noted that the viscosity of the coating liquid can be controlled by condensation or by using a thickener.

[0046] (Laminated body formation process)

[0047] The laminate formation process is a process of forming a laminate comprising an anode foil, a cathode foil, and a separator disposed between the anode foil and the cathode foil. The laminate formation process may be the following process: laminating the anode foil, the cathode foil, and the separator in such a manner that a separator is disposed between the anode foil and the cathode foil and a first conductive polymer layer is opposite to an inorganic layer, thereby forming a laminate comprising a first conductive polymer layer and a second conductive polymer layer.

[0048] 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.

[0049] 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.

[0050] (Sealing process)

[0051] The bonding process involves bonding the first conductive polymer layer to the inorganic layer by impregnating the laminate with a liquid containing an organic solvent (hereinafter, sometimes referred to as "liquid (L)"). At least a portion of the liquid (L) impregnated into the laminate is removed from the laminate after the bonding process. The method for removing the liquid (L) is not limited and heating or the like can be used. During the bonding process, the adhesion between the first conductive polymer layer formed on the diaphragm and the second conductive polymer layer formed on the dielectric layer is also improved.

[0052] 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 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, the capacitance of the anode foil can be extracted only. On the other hand, inorganic layers tend to repel water. Therefore, in conventional methods that form a conductive polymer layer by impregnating an aqueous dispersion of conductive polymers into the laminate (capacitor element), the conductive polymers have difficulty penetrating between the inorganic layer of the cathode foil and the anode foil in the laminate. Consequently, a uniform conductive polymer layer cannot be formed on the separator disposed between the cathode foil and the anode foil, leading to an increase in ESR. In the manufacturing method (M), a separator with a first conductive polymer layer pre-formed is used to form the laminate (capacitor element). Therefore, uneven distribution of conductive polymers within the separator can be suppressed. Furthermore, by using a liquid (L) containing an organic solvent for the bonding process, the conductive polymer is bonded to the inorganic layer without being repelled by the inorganic layer. For example, when a carbon layer is used as the inorganic layer, the conductive polymer becomes entangled with the carbon. Therefore, the first conductive polymer layer can be firmly bonded to the inorganic layer, reducing the resistance between them. As a result, electrolytic capacitors with low ESR can be manufactured.

[0053] 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 xylitol and xylitol derivatives.

[0054] 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 inorganic layer of 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).

[0055] The sugar alcohol can be at least one selected from mannitol, mannitol derivatives, xylitol, and xylitol derivatives, or only one of these at least one. Substance X can 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 inorganic layer of 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.

[0056] 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 it may contain only that one. By containing these substances in the liquid (L), the conductivity of the conductive polymer layer can be improved.

[0057] 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.

[0058] (Immersion process)

[0059] The manufacturing method (M) may include an impregnation step after the sealing step. The impregnation step is the process of impregnating a liquid component into the 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.

[0060] 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.

[0061] As described above, a capacitor element (e.g., 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 into an outer casing can also be performed.

[0062] It should be noted that the sealing process and the impregnation process can be performed simultaneously. In this case, liquid (L) is added to the liquid component (LC), allowing it to impregnate the laminate, and a portion of the liquid (L) is removed. However, performing the sealing process and the impregnation process separately allows for reliable sealing of the first conductive polymer layer to the inorganic layer during the sealing process, which is therefore preferable.

[0063] (Electrolytic capacitor)

[0064] 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).

[0065] An electrolytic capacitor (E) comprises a laminate and a liquid component (liquid component (LC)) impregnated into the laminate. The laminate comprises an anode foil having a dielectric layer on its surface, a cathode foil having an inorganic layer on its surface, a separator, a first conductive polymer layer held in the separator, and a second conductive polymer layer formed on the dielectric layer. The first conductive polymer layer contains a first conductive polymer. The second conductive polymer layer contains a second conductive polymer. The area R of the first conductive polymer layer in the surface area of ​​the separator is 80% or more. The first conductive polymer layer held in the separator is tightly bonded to the inorganic layer.

[0066] 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.

[0067] The areal density of the first conductive polymer layer can be within the above-mentioned range. For example, the areal density of the first conductive polymer layer can be 0.05 mg / cm³. 2 Above and 1.0 mg / cm 2 the following.

[0068] The first conductive polymer layer may contain at least one selected from sugars, sugar alcohols, epoxy resins, and polyvinyl alcohol. The sugar alcohol may contain at least one selected from xylitol and xylitol derivatives.

[0069] 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. The titanium-containing layer may contain at least one selected from titanium and titanium compounds.

[0070] As mentioned above, the laminate can be a wound body or a laminate other than a wound body.

[0071] The peel strength between the cathode foil and the separator can be 0.5 N / cm or higher, or 1.0 N / cm or higher. There is no particular upper limit to the peel strength. The peel strength can be measured using the method described in the examples. The peel strength between the cathode foil and the separator can be improved by performing a sealing process.

[0072] 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.

[0073] 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.

[0074] (Applying liquid)

[0075] The coating solution used in the polymer layer formation process may contain conductive polymers and water. The conductive polymer (conductive polymer component) may be contained in the coating solution in particle form. The coating solution may be an aqueous dispersion of the conductive polymer (conductive polymer component). 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 contain only that one. Organic compound (C) may contain at least one selected from glycols, glycerols, sugar alcohols, sulfolane, γ-butyrolactone, and borate esters, or may contain only that one.

[0076] 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.

[0077] 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).

[0078] 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).

[0079] 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.

[0080] 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.

[0081] 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.

[0082] 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.

[0083] The content of conductive polymer components 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. It should be noted that if the coating solution contains dopants, the mass of the dopants is included in the mass of the conductive polymer components.

[0084] 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.

[0085] 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.

[0086] (Liquid component (LC))

[0087] 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.

[0088] 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.

[0089] 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.

[0090] 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.

[0091] 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.).

[0092] 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).

[0093] Among them, maleic acid, phthalic acid, benzoic acid, pyromellitic acid, and resorcinol are heat-stable and are preferred.

[0094] 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.

[0095] 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.

[0096] 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.

[0097] 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.

[0098] 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.

[0099] 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).

[0100] 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.

[0101] 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.

[0102] 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.

[0103] (Anode foil)

[0104] 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.

[0105] 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.

[0106] 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.

[0107] (Cathode foil)

[0108] The cathode foil comprises a metal foil (e.g., aluminum foil). The metal constituting the 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 greater than 15 μm and less than 300 μm.

[0109] As described above, the cathode foil includes a coating layer on its surface. The coating layer is typically formed on both sides of the cathode foil. The coating layer includes at least an inorganic layer disposed on its outermost surface. The coating layer may consist of only an inorganic layer, or it may include an inorganic layer and other layers (e.g., a layer containing titanium).

[0110] (Diaphragm)

[0111] 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.

[0112] (outer body)

[0113] 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.

[0114] 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.

[0115] 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.

[0116] 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.

[0117] Capacitor element 10 is, for example, as Figure 1 The wound body is shown. The wound body includes an anode foil 11 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.

[0118] The capacitor element 10 is formed by winding a strip of anode foil 11 and a strip of cathode foil 12 together with a separator 13 in between. The outermost periphery of the wound is fixed by a winding fixing strip 14. It should be noted that... Figure 2 This indicates the unfolded state of a portion of the fixed winding before its outermost circumference.

[0119] 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.

[0120] (Postscript)

[0121] The following technologies are disclosed through the above description.

[0122] (Technology 1)

[0123] An electrolytic capacitor comprises a laminate and a liquid component impregnated in the laminate.

[0124] The aforementioned laminate includes an anode foil having a dielectric layer on its surface, a cathode foil having an inorganic layer on its surface, a separator, and a first conductive polymer layer retained in the separator.

[0125] The aforementioned first conductive polymer layer contains a first conductive polymer.

[0126] The area of ​​the first conductive polymer layer accounts for more than 80% of the surface area of ​​the diaphragm.

[0127] The first conductive polymer layer and the inorganic layer are tightly bonded to the diaphragm.

[0128] (Technology 2)

[0129] According to the electrolytic capacitor described in Technology 1, the areal density of the first conductive polymer layer is 0.05 mg / cm³. 2 Above and 1.0 mg / cm 2 the following.

[0130] (Technology 3)

[0131] According to the electrolytic capacitor described in technique 1 or 2, the first conductive polymer layer contains at least one selected from sugar, sugar alcohol, epoxy resin and polyvinyl alcohol.

[0132] (Technology 4)

[0133] According to the electrolytic capacitor described in Technique 3, the sugar alcohol comprises at least one selected from mannitol, mannitol derivatives, xylitol, and xylitol derivatives.

[0134] (Technology 5)

[0135] An electrolytic capacitor according to any one of techniques 1 to 4, wherein the inorganic layer contains at least one selected from carbon, titanium, and nickel.

[0136] (Technology 6)

[0137] According to any one of the techniques 1 to 5, the electrolytic capacitor wherein the aforementioned laminate is a wound body.

[0138] (Technology 7)

[0139] A method for manufacturing an electrolytic capacitor, comprising:

[0140] The preparation process involves preparing an anode foil with a dielectric layer on its surface and a cathode foil with an inorganic layer on its surface.

[0141] The first polymer layer forming process forms a first conductive polymer layer within the voids of the membrane.

[0142] The laminate formation process forms a laminate comprising the aforementioned anode foil, the aforementioned cathode foil, and a separator disposed between the aforementioned anode foil and the aforementioned cathode foil; and

[0143] The sealing process involves impregnating the laminated body with a liquid containing an organic solvent to seal the first conductive polymer layer onto the inorganic layer.

[0144] The first polymer layer formation process mentioned above includes:

[0145] The first coating application step involves applying a first coating solution containing a first conductive polymer and a first liquid medium into the pores of the diaphragm; and

[0146] The first liquid medium removal step involves removing at least a portion of the first liquid medium from the first coating liquid, thereby forming the first conductive polymer layer within the voids of the diaphragm.

[0147] (Technology 8)

[0148] According to the manufacturing method of the electrolytic capacitor described in Technique 7, the areal density of the first conductive polymer layer is 0.05 mg / cm³. 2 Above and 1.0 mg / cm 2 the following.

[0149] (Technology 9)

[0150] According to the manufacturing method of the electrolytic capacitor described in Technique 7 or 8, the liquid contains at least one selected from sugar, sugar alcohol, epoxy resin and polyvinyl alcohol.

[0151] (Technology 10)

[0152] According to the method for manufacturing an electrolytic capacitor as described in Technique 9, the sugar alcohol comprises at least one selected from mannitol, mannitol derivatives, xylitol, and xylitol derivatives.

[0153] (Technology 11)

[0154] According to any one of the methods for manufacturing an electrolytic capacitor described in art 7 to 10, the organic solvent contains at least one selected from ethylene glycol, diethylene glycol, triethylene glycol, and polyethylene glycol.

[0155] (Technology 12)

[0156] The method for manufacturing an electrolytic capacitor according to any one of techniques 7 to 11 further includes an impregnation step of impregnating the aforementioned laminated body with a liquid component.

[0157] The above liquid component contains 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.

[0158] (Technology 13)

[0159] According to any one of the methods for manufacturing an electrolytic capacitor described in art 7 to 12, the inorganic layer contains at least one selected from carbon, titanium, and nickel.

[0160] (Technology 14)

[0161] According to any one of the methods for manufacturing an electrolytic capacitor described in Artificial Intelligence techniques 7 to 13, the aforementioned laminated body is a wound body.

[0162] Example

[0163] 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.

[0164] (Capacitor A1)

[0165] An electrolytic capacitor (capacitor A1) is made using the following method.

[0166] (a) Preparation of constituent components

[0167] An aluminum foil (100 μm thick) 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 (50 μm thick) that becomes the cathode foil. These carbon layers are formed using a vacuum evaporation method.

[0168] 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.

[0169] (b) Formation of a conductive polymer layer

[0170] As the coating solution, a commercially available dispersion (prepared by dispersing polyvinyl sulfonic acid (PSS)-doped polyethylene dioxythiophene (PEDOT) particles in water is prepared. Next, using a gravure coating machine, the coating solution is applied to one side of the anode foil (the surface of the dielectric layer). Then, a drying process is performed, forming a conductive polymer layer on one side of the anode foil (the surface of the dielectric layer). The drying process is carried out by heating the anode foil coated with the coating solution at 125°C for 5 minutes. Next, a conductive polymer layer is formed on the other side of the anode foil (the surface of the dielectric layer) using the same method. The coating solution is then applied to a separator and dried, thereby forming a conductive polymer layer on the separator.

[0171] (c) Formation of the wound body (layered body)

[0172] The anode foil, cathode foil, and diaphragm are cut to specified sizes. Anode and cathode lead connectors are then attached to the anode and cathode foils, respectively. Next, the anode and cathode foils are wound together with the diaphragm in between. The ends of the outer surface of the wound are then secured with a winding retaining tape. Anode and cathode leads are attached to the ends of the lead connectors protruding from the wound. The resulting wound is then subjected to a chemical conversion treatment to form a dielectric layer on the end face of the anode foil. This yields a capacitor element.

[0173] (d) Sealing process

[0174] First, a liquid (L) is prepared. The liquid (L) is an aqueous solution containing polyethylene glycol. The concentration of polyethylene glycol is set to 10% by mass. Next, the liquid (L) is allowed to permeate the wound body, and the wound body is dried by heating. This causes the carbon layer (cathode foil) to adhere to the first conductive polymer layer, and the first conductive polymer layer to adhere to the second conductive polymer layer.

[0175] (e) Infiltration of liquid components

[0176] 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).

[0177] (f) Sealing of capacitor elements

[0178] 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).

[0179] (Capacitor C1)

[0180] Except for omitting the sealing process, the electrolytic capacitor (capacitor C1) is manufactured using the same methods and conditions as capacitor A1.

[0181] (evaluate)

[0182] 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 carbon layer of the cathode foil and the separator was measured using the following method. Additionally, the proportion R of the area of ​​the first conductive polymer layer on the surface of the separator was measured using the following method.

[0183] (1) Determination of peel strength

[0184] In this embodiment, firstly, the electrolytic capacitor is disassembled, and the winding body (capacitor element 10) is removed. Next, the anode foil is pulled from the outer periphery of the winding body, and a portion of the anode foil is peeled off from the winding body. Since the adhesion between the dielectric layer on the surface of the anode foil and the separator is higher than that between the cathode foil and the separator, the separator on the inner side of the peeled anode foil is peeled off from the cathode foil on its inner side while still in close contact with the anode foil.

[0185] Next, the peeled portion of the laminate 11A (the laminate of the anode foil and the diaphragm) and the peeled portion 12A of the laminate 11A in the cathode foil are respectively placed in the peel strength testing device. The testing device uses a high-speed peel strength tester (PTS-5000K) for embossed tape manufactured by EPI Corporation.

[0186] A schematic diagram of the configuration of an example of the measuring device 20 used in the peel strength determination is shown below. Figure 3 The testing apparatus is preferably of a specification capable of performing tests according to JIS (Japanese Industrial Standard) 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-off laminate 11A 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 by pulling the aforementioned portion 12A in a second direction opposite to the first direction. The recovery device 23 has a winding roller for winding the cathode foil 12. The conveying speed of the laminate 11A (anode foil 11 and diaphragm 13) based on the feed roller 22 and the winding speed of the cathode foil 12 based on the recovery device 23 are controlled so that the position of the capacitor element 10 does not move during the test.

[0187] In this embodiment, in the measuring device 20, the laminate 11A and the cathode foil 12 are pulled such that the angle between the direction of pulling the laminate 11A (anode foil 11 and diaphragm 13) fixed to the feed sheet 21 and the direction of pulling the cathode foil 12 by the recovery device 23 is approximately 175°. At this time, the laminate 11A and the cathode foil 12 are pulled for 60 seconds, causing the cathode foil 12 and the diaphragm 13 to peel off continuously at a certain speed (160 mm / min). Then, the force of pulling the cathode foil 12 at this time is measured at sampling intervals of 0.01 seconds. The average value of the measured force of pulling the cathode foil 12 is then taken as the peel strength.

[0188] (2) Determination of proportion R

[0189] The capacitor elements of capacitors A1 and C1 were disassembled, and their respective separators were removed. Additionally, for comparison, separator monomers without an attached conductive polymer layer were prepared. Samples measuring 2 cm × 5 cm were cut from each separator and evaluated. Specifically, firstly, the separators of capacitors A1 and C1, along with the separator monomers, were arranged and scanned using a scanner to obtain their images.

[0190] Next, the acquired images were binarized using image analysis software (Adobe Photoshop, a registered trademark). At this stage, the image of the membrane monomer was used as a reference, and binarization was performed by identifying areas with attached conductive polymers as black. The ratios RA1 and RC1 of capacitor A1 were calculated based on the binarized image.

[0191] The evaluation results are shown in Table 1.

[0192]

[0193] 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, in capacitor A1 with a high ratio R, the peel strength between the cathode foil and the separator is high, and the ESR is low.

[0194] Industrial availability

[0195] This disclosure can be used for electrolytic capacitors.

[0196] Explanation of reference numerals in the attached figures

[0197] 10: Capacitor Components

[0198] 11: Anode foil

[0199] 12: Cathode foil

[0200] 13: Diaphragm

[0201] 14: Winding and fixing tape

[0202] 100: Electrolytic capacitor

[0203] 101: With a bottom shell

[0204] 102: Sealing components

[0205] 103: Seat board

[0206] 104A, 104B: Lead wires

[0207] 105A, 105B: Lead wire connectors

Claims

1. An electrolytic capacitor comprising a laminate and a liquid component impregnated into said laminate, The laminate comprises an anode foil having a dielectric layer on its surface, a cathode foil having an inorganic layer on its surface, a separator, and a first conductive polymer layer retained in the separator. The first conductive polymer layer contains a first conductive polymer. The area of ​​the first conductive polymer layer accounts for more than 80% of the surface area of ​​the membrane. The first conductive polymer layer in the diaphragm is kept in close contact with the inorganic layer.

2. The electrolytic capacitor according to claim 1, wherein, The areal density of the first conductive polymer layer is 0.05 mg / cm³. 2 Above and 1.0 mg / cm 2 the following.

3. The electrolytic capacitor according to claim 1, wherein, The first conductive polymer layer contains at least one selected from sugar, sugar alcohol, epoxy resin and polyvinyl alcohol.

4. The electrolytic capacitor according to claim 3, wherein, The sugar alcohol comprises at least one selected from mannitol, mannitol derivatives, xylitol, and xylitol derivatives.

5. The electrolytic capacitor according to claim 1, wherein, The inorganic layer contains at least one selected from carbon, titanium, and nickel.

6. The electrolytic capacitor according to claim 1, wherein, The laminated body is a wound body.

7. A method for manufacturing an electrolytic capacitor, comprising: The preparation process involves preparing an anode foil with a dielectric layer on its surface and a cathode foil with an inorganic layer on its surface. The first polymer layer forming process forms a first conductive polymer layer within the voids of the membrane. The laminate formation process forms a laminate comprising the anode foil, the cathode foil, and the diaphragm disposed between the anode foil and the cathode foil; as well as The bonding process involves impregnating the laminate with a liquid containing an organic solvent, thereby bonding the first conductive polymer layer to the inorganic layer. The first polymer layer formation process includes: The first coating liquid application process involves applying a first coating liquid containing a first conductive polymer and a first liquid medium into the pores of the diaphragm. as well as The first liquid medium removal step involves removing at least a portion of the first liquid medium from the first coating liquid, thereby forming the first conductive polymer layer within the voids of the diaphragm.

8. The method for manufacturing an electrolytic capacitor according to claim 7, wherein, The areal density of the first conductive polymer layer is 0.05 mg / cm³. 2 Above and 1.0 mg / cm 2 the following.

9. The method for manufacturing an electrolytic capacitor according to claim 7, wherein, The liquid contains at least one selected from sugar, sugar alcohol, epoxy resin and polyvinyl alcohol.

10. The method for manufacturing an electrolytic capacitor according to claim 9, wherein, The sugar alcohol comprises at least one selected from mannitol, mannitol derivatives, xylitol, and xylitol derivatives.

11. The method for manufacturing an electrolytic capacitor according to claim 7, wherein, The organic solvent contains at least one selected from ethylene glycol, diethylene glycol, triethylene glycol, and polyethylene glycol.

12. The method for manufacturing an electrolytic capacitor according to claim 7, further comprising an impregnation step of impregnating the laminate with a liquid component. The liquid component contains 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.

13. The method for manufacturing an electrolytic capacitor according to claim 7, wherein, The inorganic layer contains at least one selected from carbon, titanium, and nickel.

14. The method for manufacturing an electrolytic capacitor according to claim 7, wherein, The laminated body is a wound body.

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