Manufacturing method of electrolytic capacitor, and electrolytic capacitor

Abstract

To provide a manufacturing method of electrolytic capacitor capable of improving reliability while reducing equivalent series resistance (ESR).SOLUTION: A manufacturing method of an electrolytic capacitor includes: a preparation step of preparing an electrode foil 21 having a core 22 and a porous part 23 and an electrode lead 60; a pressing step of crushing the porous part 23 by pressing at least the electrode foil 21; joining step of, after the pressing step, joining the electrode foil 21 to the electrode lead 60; and an electrode group forming step of forming an electrode group using the electrode foil 21 joined with the electrode lead 60.SELECTED DRAWING: Figure 4

Description

[Technical field]

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

[0002] Conventionally, a wound electrolytic capacitor is known that includes an electrode group formed by winding an anode foil and a cathode foil with a separator interposed therebetween (for example, Patent Document 1). The electrolytic capacitor of Patent Document 1 includes a case that houses the electrode group, an anode lead that is connected to the anode foil and leads out of the case, and a cathode lead that is connected to the cathode foil and leads out of the case. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2017-175091 A Summary of the Invention [Problem to be solved by the invention]

[0004] At least the surface of the anode foil is usually roughened to increase the capacitance of the electrolytic capacitor. When an anode lead is connected to such a roughened surface (i.e., a low-density area), the connection strength is likely to be low and the connection resistance is likely to be high. The decrease in the connection strength leads to a decrease in the reliability of the electrolytic capacitor. Moreover, the increase in the connection resistance leads to an increase in the equivalent series resistance (ESR) of the electrolytic capacitor. In this situation, one of the objectives of the present disclosure is to improve the reliability and reduce the ESR. [Means for solving the problem]

[0005] One aspect of the present disclosure relates to a method for manufacturing an electrolytic capacitor, the method including: a preparation step of preparing an electrode foil having a core portion and a porous portion and an electrode lead, a pressing step of pressing at least the electrode foil to crush the porous portion, a joining step of joining the electrode lead to the electrode foil after the pressing step, and an electrode group formation step of forming an electrode group using the electrode foil to which the electrode lead is joined.

[0006] Another aspect of the present disclosure relates to an electrolytic capacitor comprising an electrode group including an electrode foil having a core portion and a porous portion and an electrode lead joined to the electrode foil, wherein a density of the porous portion in a joining region of the electrode foil where the electrode lead is joined is higher than a density of the porous portion in a region of the electrode foil other than the joining region. Effect of the Invention

[0007] According to the present disclosure, it is possible to improve reliability and reduce ESR. [Brief description of the drawings]

[0008] [Figure 1] 1 is a cross-sectional view illustrating a schematic diagram of an example of an electrolytic capacitor according to the present disclosure. [Diagram 2] FIG. 2 is an exploded perspective view showing a schematic diagram of an electrode group. [Diagram 3] FIG. 4 is an enlarged cross-sectional view conceptually showing a joint portion between an anode foil and an anode lead. [Figure 4] 4 is an enlarged cross-sectional view for explaining a pressing step and a joining step in the first embodiment. FIG. [Diagram 5] FIG. 11 is an enlarged cross-sectional view for explaining a pressing step and a joining step in the second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] The manufacturing method of the electrolytic capacitor and the embodiment of the electrolytic capacitor according to the present disclosure will be described below with reference to examples. However, the present disclosure is not limited to the examples described below. In the following description, specific numerical values ​​and materials may be exemplified, but other numerical values ​​and materials may be applied as long as the effects of the present disclosure are obtained.

[0010] (Method of manufacturing electrolytic capacitor) The method for manufacturing an electrolytic capacitor according to the present disclosure includes a preparation step, a pressing step, a bonding step, and an electrode group forming step. Note that the term "electrolytic capacitor" may be read as a "solid electrolytic capacitor" or a "solid-liquid hybrid electrolytic capacitor", and the term "capacitor" may be read as a "capacitor".

[0011] In the preparation step, electrode foils and electrode leads are prepared. Here, the term "preparation" encompasses both the gathering of already completed parts and the fabrication of new parts. Furthermore, "preparing parts A and B" does not only encompass the case where both parts are gathered or fabricated, but also the case where one of parts A and B is an already completed part and the other of parts A and B is a part to be newly fabricated.

[0012] The electrode foil has a core and a porous portion. The core and the porous portion may be composed of a valve metal or an alloy or compound containing a valve metal. Examples of the valve metal include aluminum, tantalum, and niobium. The porous portion has a lower density than the core, and may be formed, for example, by etching the surface of the electrode foil. The porous portion may have a large number of fine pores extending in the thickness direction of the electrode foil, or may have a large number of fine pores formed in a sponge-like shape. The electrode foil may be an anode foil or a cathode foil. When the electrode foil is an anode foil, at least a part of the porous portion may be covered with a dielectric layer (for example, an oxide of the valve metal).

[0013] The electrode lead may have a lead tab and a lead wire extending from the lead tab. The electrode lead may be made of a metal (e.g., aluminum, an aluminum alloy, copper, or a copper alloy). A coating (hereinafter also referred to as an oxide coating) formed by chemical conversion treatment may be formed on the surface of the electrode lead. The electrode lead may be an anode lead or a cathode lead.

[0014] In the pressing step, at least the electrode foil is pressed to crush the porous portion. A known pressing device can be used in the pressing step. In the pressing step, the electrode foil may be pressed in its thickness direction. In the pressing step, a part of the porous portion may be crushed. Hereinafter, the part of the porous portion that is crushed in the pressing step may be referred to as the "crushed portion." The thickness of the crushed portion may be, for example, 5% or more and 95% or less of the thickness of the porous portion excluding the crushed portion.

[0015] In the joining step, after the pressing step, an electrode lead is joined to the electrode foil. In the joining step, the electrode lead may be joined to a portion of the electrode foil including the crushed portion. In the joining step, a lead tab of the electrode lead may be joined to the electrode foil. The joining method is not particularly limited, and may be, for example, ultrasonic welding, laser welding, or resistance welding.

[0016] In this way, by joining the electrode lead to the electrode foil with the porous portion crushed, the electrode lead can be joined to a higher density portion compared to when the porous portion is not crushed. This makes it possible to increase the joining strength between the electrode foil and the electrode lead and reduce the joining resistance between the electrode foil and the electrode lead. In other words, it is possible to improve the reliability of the joining and reduce the ESR of an electrolytic capacitor including an electrode foil with such an electrode lead joined (hereinafter also referred to as an electrode foil assembly).

[0017] In the electrode group forming step, an electrode group is formed using an electrode foil (electrode foil assembly) to which an electrode lead is joined. The electrode group may include at least one of an electrode foil assembly for an anode and an electrode assembly for a cathode. The electrode group may be a wound electrode group. The electrode group may include a separator interposed between the anode foil and the cathode foil. The separator may be composed of, for example, a woven fabric, a nonwoven fabric, or a porous sheet such as a microporous membrane. The separator may be impregnated with a liquid component or an electrolytic solution, or may be impregnated with a solid electrolyte (for example, a solid electrolyte containing a conductive polymer).

[0018] In the pressing process, only the electrode foil may be pressed. In this case, the electrode lead is not crushed, so there is no need to consider deformation of the electrode lead due to pressing. Therefore, the porous part of the electrode foil can be crushed with a large pressure as necessary. However, if the electrode lead is excessively deformed, the electrode lead cannot be used in an electrolytic capacitor.

[0019] In the pressing step, the electrode foil and the electrode lead placed thereon may be pressed. In this case, since the electrode foil and the electrode lead are pressed in a state where they are aligned in advance, there is no need to perform such alignment separately when moving to the joining step after the pressing step. Therefore, the manufacturing process can be simplified.

[0020] In the pressing process, the electrode foil may be pressed with a pressure of 0.02 GPa or more and 2 GPa or less. By pressing the electrode foil with a pressure in this range, the porous portion can be crushed to a necessary and sufficient degree. Specifically, even if the electrode foil is pressed with a pressure of less than 0.02 GPa, the porous portion may not be crushed sufficiently, and if the electrode foil is pressed with a pressure of more than 2 GPa, the electrode foil may be damaged.

[0021] In the joining step, the electrode lead may be joined to the electrode foil by ultrasonic welding. In this way, when a dielectric layer is formed on the surface of the porous portion (for example, when the electrode foil is an anode foil), the electrode lead can be joined to the electrode foil while removing the dielectric layer by ultrasonic vibration. In addition, when an oxide film is formed on the surface of the electrode lead, the electrode lead can be joined to the electrode foil while removing the oxide film by ultrasonic vibration.

[0022] The method for manufacturing an electrolytic capacitor may further include a chemical conversion step of performing a chemical conversion treatment on the electrode foil after the bonding step. In this way, if the electrode foil has a dielectric layer, damage to the dielectric layer caused in the bonding step can be repaired, and leakage current of the electrolytic capacitor can be reduced.

[0023] (Electrolytic capacitor) The electrolytic capacitor according to the present disclosure includes an electrode group having an electrode foil and an electrode lead. The electrode foil has a core portion and a porous portion. The electrode lead is joined to the electrode foil. The electrode foil may be the same electrode foil as described above, and the electrode lead may be the same electrode lead as described above. The electrode foil may be an anode foil or a cathode foil. The electrode group may be a wound type electrode group and may further include a separator interposed between the anode foil and the cathode foil.

[0024] The density of the porous portion of the bonded region of the electrode foil where the electrode lead is bonded (hereinafter also referred to as a first density) is higher than the density of the porous portion of the region of the electrode foil other than the bonded region (hereinafter also referred to as a non-bonded region) (hereinafter also referred to as a second density). Since the electrode lead is bonded to the relatively dense region of the electrode foil, it is possible to increase the bonding strength and reduce the bonding resistance. As a result, it is possible to improve the reliability of the electrolytic capacitor and reduce the ESR.

[0025] The porous portion having the first density may be formed, for example, by pressing an electrode foil. The porous portion having the first density has smaller (or substantially non-existent) micropores than the porous portion having the second density, but a textured portion in which traces of micropores are observed is considered to be a porous portion. The first density may be, for example, 1.05 times or more and 1.4 times or less than the second density.

[0026] In the electrode foil, the porous portion of the bonding region may be thinner than the porous portion of the region other than the bonding region (non-bonded region). Since the electrode lead is bonded to the porous portion of the bonding region, the thickness of the portion of the electrode foil assembly corresponding to the bonding region is likely to be greater than the thickness of the portion of the non-bonded region. In contrast, in this configuration, the porous portion of the bonding region is thinner than the porous portion of the non-bonded region, so that the above-mentioned thickness difference is reduced in the electrode foil assembly. This is particularly suitable when forming a wound-type electrode group using the electrode foil assembly. The thickness of the porous portion of the bonding region may be, for example, 5% or more and 95% or less of the thickness of the porous portion of the non-bonded region.

[0027] The electrode lead may have an oxide coating having a thickness of 100 nm or more. With this configuration, the oxide coating can suppress leakage current in the electrode lead. In addition, since the electrode lead is a member having no etching layer, high bonding strength can be achieved.

[0028] The surface of the bonding region of the electrode foil (hereinafter also referred to as the foil surface) and the surface of the region of the electrode lead corresponding to the bonding region (hereinafter also referred to as the lead surface) may each have an uneven shape. The foil surface and the lead surface may each be exposed to the outside of the electrode foil assembly. The pitch of the uneven shape of the foil surface (e.g., the distance between adjacent convex portions) may be smaller or larger than the pitch of the uneven shape of the lead surface. Furthermore, both pitches may be equal to each other. The height difference of the uneven shape of the foil surface (e.g., the height direction distance between the apex of the convex portion and the lowest point of the concave portion) may be smaller or larger than the height difference of the uneven shape of the lead surface. Furthermore, both height differences may be equal to each other.

[0029] As described above, according to the present disclosure, by joining an electrode lead to an electrode foil having a high-density porous portion, it is possible to improve the reliability of an electrolytic capacitor and reduce the ESR.

[0030] In the following, an example of the manufacturing method of an electrolytic capacitor and an electrolytic capacitor according to the present disclosure will be specifically described with reference to the drawings. The above-mentioned steps and components can be applied to the manufacturing method of an electrolytic capacitor and the steps and components of the electrolytic capacitor of the example described below. The manufacturing method of an electrolytic capacitor and the steps and components of the electrolytic capacitor of the example described below can be modified based on the above description. In addition, the matters described below may be applied to the above embodiment. Among the manufacturing method of an electrolytic capacitor and the steps and components of the electrolytic capacitor of the example described below, steps and components that are not essential to the manufacturing method of an electrolytic capacitor and the electrolytic capacitor according to the present disclosure may be omitted. Note that the figures shown below are schematic and do not accurately reflect the shape and number of actual members.

[0031] First Embodiment A first embodiment of the present disclosure will be described below. First, an electrolytic capacitor 10 of the present embodiment will be described, and then a method for manufacturing the electrolytic capacitor of the present embodiment will be described.

[0032] (Electrolytic capacitor) As shown in FIG. 1 to FIG. 3, the electrolytic capacitor 10 of this embodiment includes an electrode group 20, a bottomed case 30 that houses the electrode group 20, a sealing member 40 that closes the opening of the bottomed case 30, a seat plate 50 that covers the sealing member 40, lead wires 61, 71 that are led out from the sealing member 40 and pass through the seat plate 50, and lead tabs 62, 72 that connect the lead wires 61, 71 to the electrodes of the electrode group 20. The vicinity of the open end of the bottomed case 30 is drawn inward, and the open end is curled to crimp the sealing member 40. One of the lead wires 61 and the lead tab 62 constitutes an anode lead 60, and the other of the lead wires 71 and the lead tab 72 constitutes a cathode lead 70. The anode lead 60 and the cathode lead 70 have an oxide coating (not shown) with a thickness of 100 nm or more. The anode lead 60 is an example of an electrode lead.

[0033] The electrode group 20 is, for example, a wound body as shown in FIG. 2. The wound body includes an anode foil 21 connected to a lead tab 62 of an anode lead 60, a cathode foil 24 connected to a lead tab 72 of a cathode lead 70, and a separator 25 interposed between the anode foil 21 and the cathode foil 24. As shown in FIG. 3, the anode foil 21 includes a core portion 22, a porous portion 23, and a dielectric layer (not shown) formed on the surface of the porous portion 23. The density of the porous portion 23 is lower than the density of the core portion 22 (hereinafter, also referred to as a third density). A conductive polymer layer (not shown) containing a conductive polymer is formed on the surface of the dielectric layer. The anode foil 21 is an example of an electrode foil.

[0034] Examples of conductive polymers include polypyrrole, polythiophene, polyfuran, polyaniline, polyacetylene, and derivatives thereof. The derivatives include polymers having polypyrrole, polythiophene, polyfuran, polyaniline, and polyacetylene as a basic skeleton. For example, derivatives of polythiophene include poly(3,4-ethylenedioxythiophene). These conductive polymers may be used alone or in combination. The conductive polymer may be a copolymer of two or more monomers. The weight-average molecular weight of the conductive polymer is not particularly limited, and may be in the range of, for example, 1,000 to 100,000. A preferred example of the conductive polymer is poly(3,4-ethylenedioxythiophene) (PEDOT).

[0035] The conductive polymer may be doped with a dopant. From the viewpoint of suppressing dedoping from the conductive polymer, it is preferable to use a polymer dopant as the dopant. Examples of polymer dopants include polyvinyl sulfonic acid, polystyrene sulfonic acid, polyallyl sulfonic acid, polyacryl sulfonic acid, polymethacryl sulfonic acid, poly(2-acrylamido-2-methylpropane sulfonic acid), polyisoprene sulfonic acid, polyacrylic acid, and the like. These may be used alone or in combination of two or more. At least a part of these may be added in the form of a salt. A preferred example of the dopant is polystyrene sulfonic acid (PSS). The weight average molecular weight of the dopant is not particularly limited. From the viewpoint of facilitating the formation of a homogeneous conductive polymer layer, the weight average molecular weight of the dopant may be in the range of 1000 to 100,000.

[0036] The electrolytic capacitor 10 may include a liquid component (e.g., an electrolyte) impregnated in the electrode group 20. Examples of the liquid component include a nonaqueous solvent and an electrolyte. The electrolyte may be a mixture of a nonaqueous solvent and an ionic substance (solute, e.g., an organic salt) dissolved therein. The nonaqueous solvent may be an organic solvent or an ionic liquid. Examples of the nonaqueous solvent that can be used include ethylene glycol, propylene glycol, sulfolane, γ-butyrolactone, and N-methylacetamide. Examples of the organic salt include trimethylamine maleate, triethylamine borodisalicylate, ethyldimethylamine phthalate, mono-1,2,3,4-tetramethylimidazolinium phthalate, and mono-1,3-dimethyl-2-ethylimidazolinium phthalate. In this specification, the liquid component may be a component that is liquid at room temperature (25°C) or a component that is liquid at the temperature at which the electrolytic capacitor is used.

[0037] The anode foil 21 and the cathode foil 24 are wound with a separator 25 interposed therebetween. The outermost periphery of the wound body is fixed with a stop tape 26. Note that Fig. 2 shows a partially unfolded state of the wound body before the outermost periphery is fixed.

[0038] As shown in FIG. 3, the density (first density) of the porous portion 23 in the bonding region R1, which is the region of the anode foil 21 to which the anode lead 60 is bonded, is higher than the density (second density) of the porous portion 23 in the region (non-bonded region R2) other than the bonding region R1 of the anode foil 21. The first density may be lower than the above-mentioned third density. In the anode foil 21, the porous portion 23 in the bonding region R1 is thinner than the porous portion 23 in the non-bonded region R2. The above-mentioned oxide film may be removed from the portion of the anode lead 60 bonded to the bonding region R1. FIG. 3 is a cross-sectional view taken along a cross section perpendicular to the longitudinal direction of the anode foil 21.

[0039] (Method of manufacturing electrolytic capacitor) The manufacturing method for the electrolytic capacitor of this embodiment can be used to manufacture, for example, electrolytic capacitor 10 of this embodiment, and includes a preparation step, a pressing step, a joining step, and an electrode group formation step. Note that, although the joining of anode foil 21 and anode lead 60 will be described below, a similar method may be applied to the joining of cathode foil 24 and cathode lead 70.

[0040] In the preparation step, anode foil 21 having core portion 22 and porous portion 23, and anode lead 60 are prepared.

[0041] 4, in the pressing step, only the anode foil 21 is pressed with a pressing member 80 provided in the pressing machine to crush the porous portion 23, thereby forming the crushed portion 23a. In the pressing step, the anode foil 21 may be pressed with a pressure of 0.02 GPa or more and 2 GPa or less.

[0042] In the joining step, as shown in FIG. 4, after the pressing step, an ultrasonic horn 90 provided in the ultrasonic welding machine is used to join the anode lead 60 to the crushed portion 23a of the anode foil 21 by ultrasonic welding.

[0043] In the electrode group forming step, anode foil 21 to which anode lead 60 is joined, cathode foil 24 to which cathode lead 70 is joined, and separator 25 are stacked and wound together to form wound-type electrode group 20.

[0044] Second Embodiment A second embodiment of the present disclosure will be described. The method for manufacturing an electrolytic capacitor of this embodiment differs from the first embodiment in the pressing step. Specifically, as shown in Fig. 5, in the pressing step of this embodiment, a pressing member 80 included in a pressing machine is used to press the anode foil 21 and the anode lead 60 placed thereon. The other configurations are the same as those of the first embodiment, and therefore will not be described.

[0045] <Additional Notes> The above description of the embodiments discloses the following techniques. (Technology 1) a preparation step of preparing an electrode foil having a core portion and a porous portion and an electrode lead; a pressing step of pressing at least the electrode foil to crush the porous portion; a joining step of joining the electrode lead to the electrode foil after the pressing step; an electrode group forming step of forming an electrode group using the electrode foil to which the electrode lead is joined; A method for manufacturing an electrolytic capacitor comprising the steps of: (Technology 2) The method for producing an electrolytic capacitor according to technique 1, wherein in the pressing step, only the electrode foil is pressed. (Technology 3) The method for producing an electrolytic capacitor according to technique 1, wherein in the pressing step, the electrode foil and the electrode lead overlapped thereon are pressed. (Technology 4) 4. The method for producing an electrolytic capacitor according to any one of Techniques 1 to 3, wherein in the pressing step, the electrode foil is pressed with a pressure of 0.02 GPa or more and 2 GPa or less. (Technology 5) 5. The method for producing an electrolytic capacitor according to any one of Techniques 1 to 4, wherein in the joining step, the electrode lead is joined to the electrode foil by ultrasonic welding. (Technology 6) An electrode foil having a core portion and a porous portion; an electrode lead joined to the electrode foil; An electrode group having An electrolytic capacitor, wherein the density of the porous portion in a bonding region of the electrode foil where the electrode lead is bonded is higher than the density of the porous portion in a region of the electrode foil other than the bonding region. (Technology 7) The electrolytic capacitor according to claim 6, wherein in the electrode foil, the porous portion in the bonding region is thinner than the porous portion in a region other than the bonding region. (Technology 8) The electrolytic capacitor according to claim 6 or 7, wherein the electrode lead has an oxide coating having a thickness of 100 nm or more. EXAMPLES

[0046] The electrode foil assemblies of Examples 1 to 3 and Comparative Examples 1 and 2 shown below were evaluated for the bond strength and bond resistance between the electrode foil and the electrode lead (hereinafter simply referred to as bond strength and bond resistance). Note that, in order to evaluate the bond strength, with the electrode lead of the electrode foil assembly fixed to a balance, portions of the electrode foil on both sides of the electrode lead were pulled, and the maximum value measured by the balance until the electrode foil and the electrode lead were separated was taken as the bond strength.

[0047] Example 1 An electrode foil having a thickness of 115 μm and a porous portion having a thickness of about 40 μm was prepared, and pressed at a pressure of 0.02 GPa. An electrode lead having a 28 nm thick oxide film was then ultrasonically bonded to the electrode foil to obtain an electrode foil assembly. The density of the porous portion after pressing was 1.05 times that of the porous portion before pressing. In this electrode foil assembly, the bonding strength was 6.2 N, and the bonding resistance was 0.64 mΩ.

[0048] Example 2 An electrode foil having a thickness of 115 μm and a porous portion having a thickness of about 40 μm was prepared, and pressed at a pressure of 0.1 GPa. An electrode lead having a 28 nm thick oxide film was then ultrasonically bonded to the electrode foil to obtain an electrode foil assembly. The density of the porous portion after pressing was 1.08 times that of the porous portion before pressing. In this electrode foil assembly, the bonding strength was 8.3 N, and the bonding resistance was 0.62 mΩ.

[0049] Example 3 An electrode foil having a thickness of 115 μm and a porous portion having a thickness of about 40 μm was prepared, and pressed at a pressure of 2 GPa. An electrode lead having a 28 nm thick oxide film was then ultrasonically bonded to the electrode foil to obtain an electrode foil assembly. The density of the porous portion after pressing was 1.4 times that of the porous portion before pressing. In this electrode foil assembly, the bonding strength was 10.4 N and the bonding resistance was 0.58 mΩ.

[0050] Comparative Example 1 An electrode foil having a thickness of 115 μm and a porous portion having a thickness of about 40 μm was prepared, and an electrode lead having a 28 nm thick oxide film was ultrasonically bonded to the electrode foil without pressing the electrode foil to obtain an electrode foil assembly. In this electrode foil assembly, the bonding strength was less than 1 N and the bonding resistance was 0.65 mΩ.

[0051] Comparative Example 2 An electrode foil having a thickness of 115 μm and a porous portion having a thickness of about 40 μm was prepared, and an electrode lead having a 28 nm thick oxide film was connected to the electrode foil by crimping (a connection method in which a part of the electrode lead is crimped to the electrode foil) without pressing the electrode foil to obtain an electrode foil assembly. In this electrode foil assembly, the joint strength was 5.93 N and the joint resistance was 0.63 mΩ.

[0052] As described above, the electrode foil assemblies of Examples 1 to 3 had higher bonding strength than the electrode foil assemblies of Comparative Examples 1 and 2. In addition, the electrode foil assemblies of Examples 2 and 3 had lower bonding resistance than the electrode foil assemblies of Comparative Examples 1 and 2. When comparing only those that used ultrasonic bonding, all of the electrode foil assemblies of Examples 1 to 3 had higher bonding strength and lower connection resistance than the electrode foil assembly of Comparative Example 1. [Industrial Applicability]

[0053] The present disclosure can be used for a manufacturing method of an electrolytic capacitor and for an electrolytic capacitor. [Explanation of symbols]

[0054] 10: Electrolytic capacitor 20: Electrode group 21: Anode foil (electrode foil) 22: Core 23: Porous part 23a: Crushed part 24: Cathode foil 25: Separator 26: Winding tape 30: Bottomed case 40: Sealing member 50: Seat board 60: Anode lead (electrode lead) 61: Lead wire 62: Lead tab 70: Cathode lead 71: Lead wire 72: Lead tab 80: Press material 90: Ultrasonic horn R1: Junction area R2: Non-bonded area

Claims

1. a preparation step of preparing an electrode foil having a core portion and a porous portion and an electrode lead; a pressing step of pressing at least the electrode foil to crush the porous portion; a joining step of joining the electrode lead to the electrode foil after the pressing step; an electrode group forming step of forming an electrode group using the electrode foil to which the electrode lead is joined; A method for manufacturing an electrolytic capacitor comprising the steps of:

2. The method for producing an electrolytic capacitor according to claim 1 , wherein in the pressing step, only the electrode foil is pressed.

3. The method for producing an electrolytic capacitor according to claim 1 , wherein the electrode foil and the electrode lead overlapping the electrode foil are pressed in the pressing step.

4. The method for producing an electrolytic capacitor according to any one of claims 1 to 3, wherein in the pressing step, the electrode foil is pressed with a pressure of 0.02 GPa or more and 2 GPa or less.

5. 4. The method for manufacturing an electrolytic capacitor according to claim 1, wherein in the joining step, the electrode lead is joined to the electrode foil by ultrasonic welding.

6. An electrode foil having a core portion and a porous portion; an electrode lead joined to the electrode foil; An electrode group having An electrolytic capacitor, wherein the density of the porous portion in a bonding region of the electrode foil where the electrode lead is bonded is higher than the density of the porous portion in a region of the electrode foil other than the bonding region.

7. 7. The electrolytic capacitor according to claim 6, wherein in the electrode foil, the porous portion in the bonding region is thinner than the porous portion in a region other than the bonding region.

8. 8. The electrolytic capacitor according to claim 6, wherein the electrode lead has an oxide film having a thickness of 100 nm or more.

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