Electrolytic capacitor

Abstract

The disclosed electrolytic capacitor comprises: a wound capacitor element formed by winding a laminate, a liquid component impregnated in the capacitor element, and a bottomed cylindrical shell housing the capacitor element and the liquid component. The laminate comprises: an anode foil having a dielectric layer on its surface, a cathode foil opposite the dielectric layer of the anode foil, a spacer between the anode foil and the cathode foil, and a conductive polymer held in the spacer. In a cross-section of the capacitor element perpendicular to the winding axis, the ratio of the combined cross-sectional area of ​​the anode foil and the cathode foil to the cross-sectional area of ​​the capacitor element is 55% or more.

Description

[0001] Cross-reference of related applications

[0002] This application claims priority to Japanese Patent Application No. 2023-202785, filed on November 30, 2023, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This application relates to electrolytic capacitors. Background Technology

[0004] Previously, wound electrolytic capacitors (e.g., Patent Document 1) were known to have capacitor elements formed by winding an anode foil and a cathode foil with a spacer between them. The electrolytic capacitor in Patent Document 1 has such a capacitor element and a bottomed cylindrical housing that houses the capacitor element and the liquid components.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: International Publication No. 2018 / 181088 Summary of the Invention

[0008] The problem that the invention aims to solve

[0009] When ripple current (AC charging and discharging current) flows through an electrolytic capacitor, the capacitor element, which has internal resistance (equivalent series resistance: ESR), heats up. This heat causes evaporation of liquid components, increases ESR, and shortens the lifespan of the electrolytic capacitor. This phenomenon becomes more pronounced as the ripple current increases. In this context, this application provides an electrolytic capacitor that improves heat dissipation.

[0010] Methods for solving problems

[0011] One aspect of this application relates to an electrolytic capacitor. The electrolytic capacitor comprises: a wound capacitor element formed by winding a laminate, a liquid component impregnated in the capacitor element, and a bottomed cylindrical housing housing the capacitor element and the liquid component. The laminate comprises: an anode foil having a dielectric layer on its surface, a cathode foil opposite the dielectric layer of the anode foil, a spacer between the anode foil and the cathode foil, and a conductive polymer held in the spacer. In a cross-section of the capacitor element perpendicular to the winding axis, the ratio of the combined cross-sectional area of ​​the anode foil and the cathode foil to the cross-sectional area of ​​the capacitor element is 55% or more.

[0012] Invention Effects

[0013] According to this application, the heat dissipation of electrolytic capacitors can be improved.

[0014] While novel features of the invention are described in the appended technical solutions, the invention, in terms of both its structure and content, along with its other objects and features, can be better understood from the following detailed description with reference to the accompanying drawings. Attached Figure Description

[0015] Figure 1 This is a cross-sectional view schematically illustrating an example of the electrolytic capacitor of this application.

[0016] Figure 2 It is a schematic exploded three-dimensional view of a capacitor element.

[0017] Figure 3 This is a graph showing the heat dissipation properties of the electrolytic capacitors in each embodiment and comparative example. Detailed Implementation

[0018] The following describes embodiments of the electrolytic capacitor of this application using examples. However, this application is not limited to the examples described below. In the following description, specific values ​​and materials are sometimes illustrated, but other values ​​and materials can also be applied as long as the effects of this application can be obtained.

[0019] The electrolytic capacitor of this application comprises a capacitor element, a liquid component, and a bottomed cylindrical casing. Furthermore, as described later, the capacitor element has a conductive polymer held in place by a spacer. That is, the electrolytic capacitor of this application is a so-called solid-liquid hybrid electrolytic capacitor.

[0020] A capacitor element is a wound capacitor element formed by winding a laminate. The laminate has an anode foil, a cathode foil, a spacer, and a conductive polymer. The anode foil has a dielectric layer on its surface. The cathode foil is opposite the dielectric layer of the anode foil. The spacer is located between the anode foil and the cathode foil. The conductive polymer is held in the spacer.

[0021] The anode foil and cathode foil are each formed in a strip (or elongated sheet) shape. The anode foil and cathode foil each have a core and a porous portion made of a valve-acting metal or an alloy or compound containing a valve-acting metal. Examples of valve-acting metals include aluminum, tantalum, and niobium. The porous portion has a lower density than the core, and is formed, for example, by etching the surfaces of the anode foil and cathode foil. At least a portion of the porous portion of the anode foil is covered by the aforementioned dielectric layer (e.g., an oxide of the valve-acting metal).

[0022] The spacer is formed in the form of a strip (or elongated sheet). The spacer can be wider than the anode foil and cathode foil. The width direction of the spacer is parallel to the winding axis of the capacitor element. The spacer is made of porous sheets such as woven fabric, nonwoven fabric, or microporous membrane. In addition to conductive polymers, liquid components are impregnated in the spacer.

[0023] 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, but may range from 1,000 to 100,000. A preferred example of a conductive polymer is poly(3,4-ethylenedioxythiophene) (PEDOT).

[0024] 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, polyacrylic acid sulfonic acid, polymethacrylic acid 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). The weight-average molecular weight of the dopant is not particularly limited. From the viewpoint of easily forming a homogeneous conductive polymer layer, the weight-average molecular weight of the dopant is preferably in the range of 1,000 to 100,000.

[0025] A liquid component is impregnated into the capacitor element. The liquid component can be an electrolyte. Examples of liquid components include non-aqueous solvents and electrolytes. The electrolyte can be a mixture of a non-aqueous solvent and an ionic substance (solute, such as an organic salt) dissolved therein. The non-aqueous solvent can be an organic solvent or an ionic liquid. Examples of non-aqueous solvents include ethylene glycol, propylene glycol, sulfolane, γ-butyrolactone, and N-methylacetamide. 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. It should be noted that, in this specification, the liquid component can 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.

[0026] A bottomed cylindrical housing houses the capacitor elements and the liquid components. The housing can be made of metal (e.g., aluminum or aluminum alloy). The housing may have an opening that can be sealed by a sealing member.

[0027] As a feature of the electrolytic capacitor of this application, in a cross-section of the capacitor element perpendicular to the winding axis, the ratio of the total cross-sectional area of ​​the anode foil and the cathode foil to the cross-sectional area of ​​the capacitor element is 55% or more. This ratio can be, for example, 55% or more and 85% or less, preferably 55% or more and 80% or less. Here, the cross-sectional area of ​​the capacitor element is the area of ​​a cross-section perpendicular to the winding axis at any point in the central region of the capacitor element when the capacitor element is divided into three equal parts along its winding axis direction. Regarding the cross-sectional area of ​​the capacitor element, the maximum diameter of this cross-section is set as D. max And let the minimum diameter of this cross section be D. min Approximately as π·{(D) max +D min ) / 2} 2 / 4=π·(D max +D min ) 2 / 16 is calculated. That is, in this specification, the cross-sectional area of ​​the capacitor element in this section is approximately calculated as the area of ​​a circle whose diameter is the average of the maximum and minimum diameters of this section. This section includes the cross-sections of the helical anode foil, cathode foil, and spacer. Furthermore, the total cross-sectional area of ​​the anode foil and cathode foil (i.e., the sum of the cross-sectional areas of the anode foil and the cathode foil) accounts for more than 55% of the cross-sectional area of ​​the capacitor element. It should be noted that the cross-sectional area of ​​the anode foil (and cathode foil) is calculated as follows: the capacitor element is disassembled, and the thickness and length of the anode foil (and cathode foil) in this section are measured, and the area is approximately calculated as the product of these two. At this time, the thickness of the anode foil (and cathode foil) is calculated as the average of the measured thicknesses at any 5 points, and the length of the anode foil (and cathode foil) is the maximum length measured along its length direction.

[0028] Here, the thermal conductivity of the anode foil and cathode foil is higher than that of the spacer. In the electrolytic capacitor of this application, the capacitor element is configured as described above, resulting in anode and cathode foils with high thermal conductivity occupying a large volume. Therefore, when ripple current flows through the electrolytic capacitor, even if heat is generated inside the capacitor element, this heat can be efficiently dissipated towards the outside of the capacitor element. Furthermore, it has been found that this improvement in heat dissipation is significantly enhanced by setting the aforementioned ratio to 55% or more. Details regarding this will be described later; by setting this ratio to 55% or more, the heat dissipation performance of the electrolytic capacitor can be significantly improved.

[0029] The outermost periphery of the capacitor element can be made of cathode foil. In this case, compared to the case where the outermost periphery of the capacitor element is made of spacers, the heat generated inside the capacitor element can be dissipated towards the outside of the capacitor element more efficiently.

[0030] At least a portion of the spacer can contact the inner bottom surface of the housing. In this case, heat generated inside the capacitor element can be efficiently transferred to the housing via this contact portion. Therefore, the heat dissipation performance of the electrolytic capacitor can be further improved.

[0031] The ratio of the capacitor element's diameter (maximum diameter) to the inner diameter of the casing can be 85% or more but less than 100%. When this ratio is 85% or more, the distance between the outer circumferential surface of the capacitor element and the inner circumferential surface of the casing becomes sufficiently small, enabling efficient heat transfer between them. Therefore, the heat dissipation performance of the electrolytic capacitor can be further improved.

[0032] The materials for both the anode and cathode foils can include aluminum. In this case, heat dissipation can be achieved efficiently.

[0033] The liquid component may contain polyols. In this case, the degradation of conductive polymers caused by heating can be suppressed. Polyols are organic compounds containing two or more hydroxyl groups. Examples of polyols include glycols, glycerols, and sugar alcohols. Polyols can be hydrocarbon compounds substituted with two or more hydroxyl groups. Polyols are preferably soluble in water. The molecular weight of polyols can be, for example, 500 or less. Examples of glycols include alkylene glycols (ethylene glycol, propylene glycol, etc.), diethylene glycol, triethylene glycol, polyalkylene glycols (e.g., polyethylene glycol), polyoxyethylene-polyoxypropylene glycol (ethylene oxide-propylene oxide copolymer), etc. Examples of glycerols include glycerol and polyglycerol, etc. Examples of sugar alcohols include mannitol, xylitol, sorbitol, erythritol, and pentaerythritol, etc. A preferred example of a polyol is ethylene glycol.

[0034] As described above, according to this application, by increasing the ratio of the total cross-sectional area of ​​the anode foil and cathode foil to the overall cross-sectional area within a specified cross-section of the capacitor element, the heat dissipation of the electrolytic capacitor can be improved. Furthermore, according to this application, the degradation of the capacitor element can be suppressed, and the lifespan of the electrolytic capacitor can be extended.

[0035] Hereinafter, an example of an electrolytic capacitor according to this application will be specifically described with reference to the accompanying drawings. The above-described components can be applied to the components of the electrolytic capacitor in the example described below. The components of the electrolytic capacitor in the example described below can be modified based on the above description. Furthermore, the matters described below can also be applied to the above-described embodiments. In the components of the electrolytic capacitor in the example described below, non-essential components of the electrolytic capacitor of this application can be omitted. It should be noted that the figures shown below are schematic and do not accurately reflect the actual shape and number of components.

[0036] like Figure 1 and Figure 2 As shown, the electrolytic capacitor 10 of this embodiment includes: a wound capacitor element 20 formed by winding a laminated body; a liquid component (not shown) impregnated in the capacitor element 20; a bottomed cylindrical housing 30 housing the capacitor element 20 and the liquid component; a sealing member 40 blocking the opening of the housing 30; a base plate 50 covering the sealing member 40; leads 61 and 71 extending from the sealing member 40 and passing through the base plate 50; and lead connectors 62 and 72 connecting the leads 61 and 71 to the electrodes of the capacitor element 20. The housing 30 is drawn inward near the opening end, and the opening end is rolled to tighten the sealing member 40. One lead 61 and lead connector 62 constitute an anode lead 60, and another lead 71 and lead connector 72 constitute a cathode lead 70.

[0037] Capacitor element 20 is as follows Figure 2 The wound body shown is constructed as described above by winding a laminate. The laminate includes: an anode foil 21 connected to the lead connector 62 of the anode lead 60, a cathode foil 22 connected to the lead connector 72 of the cathode lead 70, a spacer 23 between the anode foil 21 and the cathode foil 22, and a conductive polymer (not shown) held in the spacer 23. The anode foil 21 has a dielectric layer (not shown) on its surface. The cathode foil 22 is sandwiched between the dielectric layer of the anode foil 21 and the spacer 23. The cathode foil 22 has a conductive polymer layer (not shown) containing the conductive polymer formed on the surface of the dielectric layer. The materials of the anode foil 21 and the cathode foil 22 preferably include aluminum. The liquid component preferably includes a polyol. The liquid component can be an electrolyte.

[0038] The anode foil 21 and cathode foil 22 are wound together with a spacer 23 in between. The outermost periphery of the capacitor element 20 is formed by the cathode foil 22 and is fixed by a winding fixing tape 25. It should be noted that... Figure 2This indicates the partially unfolded state of the capacitor element 20 before its outermost periphery is fixed. At least a portion of the spacer 23 preferably contacts the inner bottom surface of the housing 30. The ratio of the diameter (maximum diameter) of the capacitor element 20 to the inner diameter of the housing 30 is preferably 85% or more and less than 100%.

[0039] In the cross-section (or cross-sectional area) of the capacitor element 20 perpendicular to the winding axis, the ratio of the total cross-sectional area of ​​the anode foil 21 and the cathode foil 22 to the cross-sectional area of ​​the capacitor element 20 is 55% or more. This significantly improves the heat dissipation of the electrolytic capacitor 10. It should be noted that this ratio can be 55% or more and 85% or less, preferably 55% or more and 80% or less. By setting the preferred upper limit of this ratio to 85% or 80%, the thickness of the spacer is ensured to a certain extent, improving the impregnation of the conductive polymer, thereby suppressing the increase in ESR of the electrolytic capacitor 10.

[0040] Postscript

[0041] The following technology has been disclosed through the above description of the embodiments.

[0042] (Technology 1)

[0043] An electrolytic capacitor comprising:

[0044] A wound capacitor element formed by winding a laminated body.

[0045] The liquid components impregnated in the above-mentioned capacitor elements, and

[0046] A bottomed cylindrical housing that houses the aforementioned capacitor elements and the aforementioned liquid components.

[0047] The above-mentioned laminated body has:

[0048] Anode foil with a dielectric layer on its surface,

[0049] The cathode foil opposite the dielectric layer of the anode foil,

[0050] The spacer between the anode foil and the cathode foil, and

[0051] The conductive polymer held in the aforementioned spacer

[0052] In the cross-section of the capacitor element perpendicular to the winding axis, the ratio of the total cross-sectional area of ​​the anode foil and the cathode foil to the cross-sectional area of ​​the capacitor element is 55% or more.

[0053] (Technology 2)

[0054] According to the electrolytic capacitor described in Technique 1, the outermost periphery of the capacitor element is composed of the cathode foil.

[0055] (Technology 3)

[0056] According to the electrolytic capacitor described in Art 1 or 2, at least a portion of the spacer is in contact with the inner bottom surface of the housing.

[0057] (Technology 4)

[0058] According to any one of the techniques 1 to 3, the ratio of the diameter of the capacitor element to the inner diameter of the housing is 85% or more and less than 100%.

[0059] (Technology 5)

[0060] According to any one of the techniques 1 to 4, the electrolytic capacitor is made of aluminum, wherein the anode foil and the cathode foil are made of aluminum.

[0061] (Technology 6)

[0062] An electrolytic capacitor according to any one of techniques 1 to 5, wherein the liquid component comprises a polyol.

[0063] Example

[0064] The heat dissipation performance of the electrolytic capacitors of Examples 1-6 and Comparative Examples 1-12 shown below was evaluated. Furthermore, the evaluation of heat dissipation performance was performed based on the magnitude of the heat dissipation coefficient β of each electrolytic capacitor obtained according to steps 1-4 below.

[0065] (Step 1) Fabricate an electrolytic capacitor and determine the relationship between its ESR and temperature (the surface temperature of the casing) (i.e., the temperature characteristics of the ESR).

[0066] (Step 2) Mount the electrolytic capacitor onto the substrate.

[0067] (Step 3) With a thermocouple mounted on the surface of the casing (specifically, the top surface), apply a ripple current to the electrolytic capacitor. Then, leave it in standby mode until the temperature obtained from the thermocouple stabilizes, and calculate the temperature rise based on the difference between the stable temperature and the ambient temperature. Perform these processes for various ripple currents.

[0068] (Step 4) Let R (unit: Ω) be the ESR of the electrolytic capacitor after heating, which is obtained from the temperature characteristics of ESR in Step 1; let I (unit: A) be the effective value of the ripple current applied in Step 3; and let S (unit: cm²) be the surface area of ​​the electrolytic capacitor casing. 2And set the temperature rise calculated in step 3 as ΔT (unit: °C), so that S·ΔT corresponds to the horizontal axis (x-axis) and R·I 2 The slope corresponding to the vertical axis (y-axis) is used as the heat dissipation coefficient β (unit: W / (℃·cm)). 2 And thus obtained.

[0069] Example 1

[0070] The heat dissipation performance of the electrolytic capacitor corresponding to Embodiment 1, namely, an electrolytic capacitor in which the ratio of the total cross-sectional area of ​​the anode foil and cathode foil to the cross-sectional area of ​​the capacitor element (hereinafter referred to as the area ratio) in the cross-section perpendicular to the winding axis of the capacitor element is 55.2%, the outermost periphery of the capacitor element is composed of cathode foil, at least a portion of the spacer is in contact with the inner bottom surface of the housing, and the ratio of the diameter of the capacitor element to the inner diameter of the housing is 85% or more and less than 100%, was evaluated. The heat dissipation coefficient β of the electrolytic capacitor of Comparative Example 9 was set to 1.00, and the heat dissipation coefficient of the electrolytic capacitor of Embodiment 1 was 1.29.

[0071] Example 2

[0072] The heat dissipation performance of the electrolytic capacitor corresponding to Embodiment 1, namely, an electrolytic capacitor with an area ratio of 55.6%, an outermost periphery of the capacitor element composed of cathode foil, at least a portion of the spacer in contact with the inner bottom surface of the casing, and a ratio of the diameter of the capacitor element to the inner diameter of the casing of 85% or more and less than 100%, was evaluated. The heat dissipation coefficient β of the electrolytic capacitor of Comparative Example 9 was set to 1.00, and the heat dissipation coefficient of the electrolytic capacitor of Example 2 was 1.33.

[0073] Example 3

[0074] The heat dissipation performance of the electrolytic capacitor corresponding to Embodiment 1, namely, an electrolytic capacitor with an area ratio of 55.8%, an outermost periphery of the capacitor element composed of cathode foil, at least a portion of the spacer in contact with the inner bottom surface of the casing, and a ratio of the diameter of the capacitor element to the inner diameter of the casing of 85% or more and less than 100%, was evaluated. The heat dissipation coefficient β of the electrolytic capacitor of Comparative Example 9 was set to 1.00, and the heat dissipation coefficient of the electrolytic capacitor of Example 3 was 1.35.

[0075] Example 4

[0076] The heat dissipation performance of the electrolytic capacitor corresponding to Embodiment 1, namely, an electrolytic capacitor with an area ratio of 56.7%, an outermost periphery of the capacitor element composed of cathode foil, at least a portion of the spacer in contact with the inner bottom surface of the casing, and a ratio of the diameter of the capacitor element to the inner diameter of the casing of 85% or more and less than 100%, was evaluated. The heat dissipation coefficient β of the electrolytic capacitor of Comparative Example 9 was set to 1.00, and the heat dissipation coefficient of the electrolytic capacitor of Example 4 was 1.43.

[0077] Example 5

[0078] The heat dissipation performance of the electrolytic capacitor corresponding to Embodiment 1, namely, an electrolytic capacitor with an area ratio of 57.1%, an outermost periphery of the capacitor element composed of cathode foil, at least a portion of the spacer in contact with the inner bottom surface of the casing, and a ratio of the diameter of the capacitor element to the inner diameter of the casing of 85% or more and less than 100%, was evaluated. The heat dissipation coefficient β of the electrolytic capacitor of Comparative Example 9 was set to 1.00, and the heat dissipation coefficient of the electrolytic capacitor of Example 5 was 1.49.

[0079] Example 6

[0080] The heat dissipation performance of the electrolytic capacitor corresponding to Embodiment 1, namely, an electrolytic capacitor with an area ratio of 57.5%, an outermost periphery of the capacitor element composed of cathode foil, at least a portion of the spacer in contact with the inner bottom surface of the housing, and a ratio of the diameter of the capacitor element to the inner diameter of the housing of 85% or more and less than 100%, was evaluated. The heat dissipation coefficient β of the electrolytic capacitor of Comparative Example 9 was set to 1.00, and the heat dissipation coefficient of the electrolytic capacitor of Example 6 was 1.53.

[0081] Comparative Example 1

[0082] The heat dissipation performance of an electrolytic capacitor with an area ratio of 54.7%, an outermost periphery of the capacitor element composed of cathode foil, and at least a portion of the spacer in contact with the inner bottom surface of the casing was evaluated. The heat dissipation coefficient β of the electrolytic capacitor of Comparative Example 9 was set to 1.00, and the heat dissipation coefficient of the electrolytic capacitor of Comparative Example 1 was 1.25.

[0083] Comparative Example 2

[0084] The heat dissipation performance of an electrolytic capacitor with an area ratio of 54.2%, an outermost periphery of the capacitor element composed of cathode foil, and at least a portion of the spacer in contact with the inner bottom surface of the casing was evaluated. The heat dissipation coefficient β of the electrolytic capacitor of Comparative Example 9 was set to 1.00, and the heat dissipation coefficient of the electrolytic capacitor of Comparative Example 2 was 1.19.

[0085] Comparative Example 3

[0086] The heat dissipation performance of an electrolytic capacitor with an area ratio of 53.7%, an outermost periphery of the capacitor element composed of cathode foil, and at least a portion of the spacer in contact with the inner bottom surface of the casing was evaluated. The heat dissipation coefficient β of the electrolytic capacitor of Comparative Example 9 was set to 1.00, and the heat dissipation coefficient of the electrolytic capacitor of Comparative Example 3 was 1.15.

[0087] Comparative Example 4

[0088] The heat dissipation performance of an electrolytic capacitor with an area ratio of 53.6%, an outermost periphery of the capacitor element composed of cathode foil, and at least a portion of the spacer in contact with the inner bottom surface of the casing was evaluated. The heat dissipation coefficient β of the electrolytic capacitor of Comparative Example 9 was set to 1.00, and the heat dissipation coefficient of the electrolytic capacitor of Comparative Example 4 was 1.15.

[0089] Comparative Example 5

[0090] The heat dissipation performance of an electrolytic capacitor with an area ratio of 53.2%, an outermost periphery of the capacitor element composed of cathode foil, and at least a portion of the spacer in contact with the inner bottom surface of the casing was evaluated. The heat dissipation coefficient β of the electrolytic capacitor of Comparative Example 9 was set to 1.00, and the heat dissipation coefficient of the electrolytic capacitor of Comparative Example 5 was 1.13.

[0091] Comparative Example 6

[0092] The heat dissipation performance of an electrolytic capacitor with an area ratio of 52.3%, an outermost periphery of the capacitor element composed of cathode foil, and at least a portion of the spacer in contact with the inner bottom surface of the casing was evaluated. The heat dissipation coefficient β of the electrolytic capacitor of Comparative Example 9 was set to 1.00, and the heat dissipation coefficient of the electrolytic capacitor of Comparative Example 6 was 1.08.

[0093] Comparative Example 7

[0094] The heat dissipation performance of an electrolytic capacitor with an area ratio of 52.1%, an outermost periphery of the capacitor element composed of cathode foil, and at least a portion of the spacer in contact with the inner bottom surface of the casing was evaluated. The heat dissipation coefficient β of the electrolytic capacitor of Comparative Example 9 was set to 1.00, and the heat dissipation coefficient of the electrolytic capacitor of Comparative Example 7 was 1.07.

[0095] Comparative Example 8

[0096] The heat dissipation performance of an electrolytic capacitor with an area ratio of 51.6%, an outermost periphery of the capacitor element composed of cathode foil, and at least a portion of the spacer in contact with the inner bottom surface of the casing was evaluated. The heat dissipation coefficient β of the electrolytic capacitor of Comparative Example 9 was set to 1.00, and the heat dissipation coefficient of the electrolytic capacitor of Comparative Example 8 was 1.04.

[0097] Comparative Example 9

[0098] The heat dissipation performance of an electrolytic capacitor with an area ratio of 51.1%, an outermost periphery of the capacitor element consisting of cathode foil, and at least a portion of the spacer in contact with the inner bottom surface of the casing was evaluated. The heat dissipation coefficient β of the electrolytic capacitor in Comparative Example 9 was 1.00 (reference value).

[0099] Comparative Example 10

[0100] The heat dissipation performance of an electrolytic capacitor with an area ratio of 51.1%, an outermost periphery of the capacitor element composed of cathode foil, and a spacer not in contact with the inner bottom surface of the casing was evaluated. The heat dissipation coefficient β of the electrolytic capacitor of Comparative Example 9 was set to 1.00, and the heat dissipation coefficient of the electrolytic capacitor of Comparative Example 10 was 0.86.

[0101] Comparative Example 11

[0102] The heat dissipation performance of an electrolytic capacitor with an area ratio of 51.1%, an outermost periphery of the capacitor element consisting of spacers, and at least a portion of the spacers in contact with the inner bottom surface of the casing was evaluated. The heat dissipation coefficient β of the electrolytic capacitor of Comparative Example 9 was set to 1.00, and the heat dissipation coefficient of the electrolytic capacitor of Comparative Example 11 was 0.95.

[0103] Comparative Example 12

[0104] The heat dissipation performance of an electrolytic capacitor with an area ratio of 49.9%, an outermost periphery of the capacitor element composed of cathode foil, and at least a portion of the spacer in contact with the inner bottom surface of the casing was evaluated. The heat dissipation coefficient β of the electrolytic capacitor of Comparative Example 9 was set to 1.00, and the heat dissipation coefficient of the electrolytic capacitor of Comparative Example 12 was 0.95.

[0105] The above evaluation results are presented in the form of a graph that aligns the area ratio with the horizontal axis and the relative value of the heat dissipation coefficient β with the vertical axis. Figure 3 According to the graph (especially the difference in slope between the two approximate straight lines corresponding to the multiple white circles in the chart), it can be seen that by setting the area ratio to above 55%, the heat dissipation coefficient β increases significantly, meaning the heat dissipation performance of the electrolytic capacitor is significantly improved. It should be noted that... Figure 3 In the comparison example, black circle (●) represents the reference value, white triangle (△) represents the comparison example 10 in which the spacer does not contact the housing, white quadrilateral (□) represents the comparison example 11 in which the outermost periphery of the capacitor element is composed of spacers, and white circle (○) represents all other embodiments and comparison examples.

[0106] Industrial availability

[0107] This application can be used in electrolytic capacitors.

[0108] Preferred embodiments of the present invention have been described, but such disclosure should not be interpreted as restrictive. Various modifications and alterations will be readily apparent to those skilled in the art upon reading the above disclosure. Therefore, the appended technical solutions should be interpreted as encompassing all modifications and alterations without departing from the true spirit and scope of the invention.

[0109] Explanation of reference numerals in the attached figures

[0110] 10: Electrolytic capacitors

[0111] 20: Capacitor Components

[0112] 21: Anode foil

[0113] 22: Cathode foil

[0114] 23: Spacer

[0115] 25: Winding and fixing tape

[0116] 30: Shell

[0117] 40: Sealing components

[0118] 50: Seat plate

[0119] 60: Anode lead

[0120] 61: Lead wire

[0121] 62: Lead wire connector

[0122] 70: Cathode lead

[0123] 71: Lead wire

[0124] 72: Lead wire connector

Claims

1. An electrolytic capacitor comprising: A wound capacitor element formed by winding a laminated body. The liquid components permeating the capacitor element, and A bottomed cylindrical housing that houses the capacitor element and the liquid component. The laminate has: Anode foil with a dielectric layer on its surface, The cathode foil opposite the dielectric layer of the anode foil, The spacer between the anode foil and the cathode foil, and The conductive polymer held in the spacer In the cross-section of the capacitor element perpendicular to the winding axis, the ratio of the total cross-sectional area of ​​the anode foil and the cathode foil to the cross-sectional area of ​​the capacitor element is 55% or more.

2. The electrolytic capacitor according to claim 1, wherein, The outermost periphery of the capacitor element is formed by the cathode foil.

3. The electrolytic capacitor according to claim 1 or 2, wherein, At least a portion of the spacer is in contact with the inner bottom surface of the housing.

4. The electrolytic capacitor according to claim 1 or 2, wherein, The ratio of the diameter of the capacitor element to the inner diameter of the housing is more than 85% and less than 100%.

5. The electrolytic capacitor according to claim 1 or 2, wherein, The materials of the anode foil and the cathode foil contain aluminum.

6. The electrolytic capacitor according to claim 1 or 2, wherein, The liquid component contains polyols.

Images