Capacitor and method for manufacturing a capacitor

Abstract

This specification describes a capacitor (1) comprising a capacitive element (2) provided in a case (3) sealed with a cover (4), wherein the case (3) or cover (4) includes at least one through-hole (5) covered with a gas venting element (6) configured to reduce the internal gas pressure of the capacitor (1) during its operation, the gas venting element (6) being provided on the outer surface (7) or inner surface (8) of the case (3) or cover (4), the outer surface (7) or inner surface (8) each including a surface structure (9) configured to improve the bonding between the gas venting element (6) and the outer surface (7) or inner surface (8), and the gas venting element (6) being chemically adsorbed to the case (3) or cover (4). Furthermore, this specification describes a method for manufacturing the capacitor (1).

Description

Technical Field

[0001] This specification describes a capacitor and a method for manufacturing a capacitor.

Background Art

[0002] For example, in a switch-mode power supply, a capacitor having a high CV coefficient and a long life may be used. Here, the CV coefficient corresponds to a value obtained by dividing the product of the capacitance and the operating voltage by the volume of the capacitor, and determines the volume efficiency of the capacitor. In particular, the life of a high-CV capacitor is limited by gas generation or electrolyte degradation. For example, the capacitance of an anode element is inversely proportional to the formation voltage of the anodic oxide layer, and the formation voltage of the anodic oxide layer is proportional to the thickness of the anodic oxide layer. However, when the formation voltage decreases, the leakage current flowing through the anodic oxide layer increases exponentially, which may increase the amount of gas that can be generated inside the capacitor. In addition, in a high-CV capacitor, there may not be enough free volume space to accommodate such gas. As a result, the pressure inside the capacitor may increase during operation, damaging or destroying the capacitor and shortening its life accordingly. For example, German Patent Application Publication No. 102015119844 discloses a capacitor provided with a safety vent.

[0003] At least one object of a specific embodiment is to provide a capacitor with an improved life. At least one another object of a specific embodiment is to provide a method for manufacturing a capacitor with an improved life. These objects are achieved by the capacitor and the method for manufacturing a capacitor described in the independent claims.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

[0005] Advantageous embodiments and further developments of capacitors and methods for manufacturing capacitors are described in the dependent claims. [Means for solving the problem]

[0006] According to one embodiment, the capacitor includes a capacitive element provided in a case sealed with a cover.

[0007] In particular, capacitive elements are configured to store charge during the operation of a capacitor. For example, capacitive elements can be charged and discharged during the operation of a capacitor. For example, a capacitive element includes a cathode element and an anode element that are physically separated by a dielectric element. The cathode element and the anode element may be electrically in contact by a conductive element such as a wire or lead.

[0008] For example, the case is configured to mechanically stabilize the capacitor. In particular, the case includes a cavity for housing the capacitive element. For example, the case has an opening for inserting the capacitive element into the cavity during the manufacturing of the capacitor. For example, the case has a cylindrical shape with a bottom surface and an open end surface opposite the bottom surface, the open end surface forming the opening. In particular, the case protects the capacitive element from external forces or harmful substances that could damage the capacitor during operation.

[0009] The case may be configured to electrically isolate the capacitive element from the environment outside the case. Alternatively, the case may be configured to make electrical contact with the capacitive element. For example, the case may be conductive and electrically connected to the anode or cathode element. The case may also be configured as a heat sink so that heat generated by the capacitive element during operation is efficiently transferred and dissipated from the capacitive element. For example, the capacitive element may be in thermal contact with the case.

[0010] For example, the cover and case form a sealed cavity for housing a capacitive element. In particular, the cavity is sealed by providing or attaching the cover to the opening of the case. At least one conductive element, such as a wire or lead, for electrical contact with the capacitive element may be provided inside the cover or incorporated into the cover. For example, the cover may include or consist of metal, plastic, glass, rigid paper, or rubber.

[0011] According to one embodiment of the capacitor, the case or cover includes at least one through-hole covered with a gas release element configured to reduce the gas pressure inside the capacitor during its operation.

[0012] For example, a case or cover may include one, two, three, or more through-holes. In particular, if a case or cover includes two or more through-holes, the through-holes may be grouped into one area of ​​the case or one area of ​​the cover. For example, the distance between adjacent through-holes is less than the diameter of a single through-hole. In particular, multiple through-holes may form a regular arrangement. For example, one or more through-holes may also be provided within the case and within the cover.

[0013] The following describes the characteristics of a single through-hole. For example, these characteristics are applicable to a single through-hole, most through-holes, or all through-holes. In particular, the through-hole extends completely through the case so that gas can escape from the cavity through the through-hole. For example, the through-hole has a circular, elliptical, oblong, curved, square, rectangular, or polygonal cross-section. For example, the diameter of the through-hole is 0.1 mm to 10 mm, preferably 0.5 mm to 6 mm. Here, and in the following sections, diameter refers to the maximum linear dimension of the cross-section of the through-hole.

[0014] For example, through-holes are provided on the bottom surface of the case. Here, and in the following sections, the bottom surface is located on the opposite side of the cavity opening, through which the capacitive element is inserted into the cavity during the manufacture of the capacitor. In particular, the bottom surface is flat. Alternatively or additionally, through-holes are provided on the sides of the case. In particular, the sides are provided intersecting or perpendicular to the bottom surface. For example, the sides are curved.

[0015] In particular, the gas dissipation element completely covers at least one through-hole. For example, the gas dissipation element completely covers one or more through-holes, or more through-holes. For example, the gas dissipation element completely covers an array of through-holes. For example, the gas dissipation element is provided or positioned directly on or above at least one through-hole. In other words, the gas dissipation element is not provided completely inside at least one through-hole. For example, if both the case and the cover include through-holes, the capacitor may include two or more gas dissipation elements, with at least one gas dissipation element used in the case and one gas dissipation element used in the cover.

[0016] In particular, gases that may be generated inside the sealed cavity formed by the case and cover during the operation of the capacitor can escape from the cavity through at least one through-hole and gas venting element. For example, if the partial gas pressure inside the cavity is greater than the partial gas pressure outside the cavity, the gas can diffuse or permeate out of the cavity through the gas venting element. In particular, liquids such as electrolytes cannot permeate through the gas venting element. In other words, liquids, for example, are sealed inside the cavity.

[0017] According to at least one further embodiment of the capacitor, the gas dissipation element is provided on the outer or inner surface of the case or cover. Here, and in the following parts, the inner surface is the surface facing the capacitive element, and the outer surface is the surface opposite to the inner surface. In particular, neither the outer nor the inner surface includes the side walls of the through-hole.

[0018] According to at least one further embodiment of the capacitor, the outer or inner surface includes a surface structure configured to improve the coupling between the gas dissipation element and the outer or inner surface. For example, the surface structure completely encloses a through-hole. For example, the surface structure includes a surface region with increased surface roughness. For example, the surface structure includes or consists of one or more recesses. In particular, the recess completely encloses a through-hole, or the through-hole is formed inside the recess. For example, the depth of the recess is at most half the thickness of the case or cover.

[0019] According to at least one further embodiment of the capacitor, the gas venting element is chemically adsorbed to the case or cover. For example, no adhesive is used when attaching the gas venting element to the outer or inner surface. In particular, a direct chemical bond is formed between the gas venting element and the case or cover so that a liquid-tight seal is formed. For example, the chemical bond may be a primary bond, a secondary bond, or a van der Waals bond.

[0020] According to one embodiment, the capacitor includes a capacitive element provided in a case sealed with a cover, the case or cover includes at least one through-hole covered with a gas venting element configured to reduce the gas pressure inside the capacitor during the operation of the capacitor, the gas venting element is provided on the outer or inner surface of the case or cover, the outer or inner surface each includes a surface structure configured to improve the bonding between the gas venting element and the outer or inner surface, and the gas venting element is chemically adsorbed to the case or cover.

[0021] The capacitor disclosed in this specification is based on the idea of extending the life of a high CV capacitor by providing a gas diffusion element that reduces the internal pressure of the capacitor during operation. For example, when charging or discharging the capacitor, gases such as H2, CO2, ethane, ethylene or other low molecular weight gases can be generated inside the capacitor by an electrochemical process. As a result, the internal pressure of the capacitor may increase during operation. For example, if the internal pressure of the capacitor becomes too large, the capacitor may be damaged or broken. Advantageously, with the gas diffusion element, such gases can escape from the capacitor, thereby reducing the internal pressure of the capacitor. Therefore, the life of the capacitor is prolonged. Also, for example, the liquid electrolyte remains sealed inside the capacitor.

[0022] Also, for example, compared with a gas diffusion element mechanically clamped inside a through-hole, providing the gas diffusion element so as to cover the through-hole can simplify the manufacturing process, thereby reducing the manufacturing cost. Also, for example, since an element for clamping the gas diffusion element inside the through-hole is not required, the total thickness of the case and the gas diffusion element can be advantageously reduced.

[0023] According to at least one further embodiment of the capacitor, the gas diffusion element comprises or consists of a gas diffusion layer. In particular, gases generated inside the capacitor during operation may diffuse or permeate through the gas diffusion layer or soak into the gas diffusion layer. For example, the gas permeability of the gas diffusion element to H2 is 10 10 cm 2 / (s·atm) to 10 13 cm 2 / (s·atm).

[0024] According to at least one further embodiment of the capacitor, the gas diffusion element comprises or consists of at least one of a polymer, a metal organic framework or a silicon material. For example, the gas diffusion element comprises or consists of a gas diffusion layer, for example, the gas diffusion layer comprises or consists of a polymer, silicone, metal organic framework, silicon, silicon nitride or silicon carbide.

[0025] According to at least one further embodiment of the capacitor, the gas diffusion element extends at least partially into the through-hole. For example, the gas diffusion layer covers the through-hole and comprises a polymer that extends partially or completely into the through-hole. For example, the through-hole may be partially or completely filled with a polymer.

[0026] According to at least one further embodiment of the capacitor, the thickness of the gas diffusion element is 0.1 mm to 2.5 mm. The thickness of the gas diffusion element may take a value of 0.1 mm to 3 mm. For example, the thickness of the gas diffusion layer is 0.1 mm to 2.5 mm. In particular, the thickness refers to the spatial dimension in a direction parallel to the through-hole. In other words, the thickness refers to the spatial dimension in a direction parallel to the central axis of the through-hole.

[0027] According to at least one further embodiment of the capacitor, when the case includes a through-hole, the total thickness of the case and the gas diffusion element is at most 2.5 mm. In particular, the total thickness refers to the total thickness of the gas diffusion element and the case.

[0028] According to at least one further embodiment of the capacitor, when the cover includes a through-hole, the total thickness of the cover and the gas diffusion element is at most 3.5 mm. In particular, the total thickness refers to the total thickness of the gas diffusion element and the cover.

[0029] According to at least one further embodiment of the capacitor, molecules with a molecular weight of less than 60 Da can penetrate the gas diffusion element. In particular, H2 can penetrate or permeate the gas diffusion element.

[0030] According to at least one further embodiment of the capacitor, the case includes or is made of a metal such as aluminum. Alternatively or additionally, for example, the case includes or is made of a plastic or polymer.

[0031] According to at least one further embodiment of the capacitor, the capacitive element is a wound element containing a liquid electrolyte with a water content of at least 2% by weight. In particular, the wound element includes a cathode foil and an anode foil wound around each other and separated by a dielectric. For example, the capacitor is an aluminum electrolytic capacitor. For example, the wound element is partially or completely immersed in the liquid electrolyte.

[0032] According to at least one further embodiment of the capacitor, the volume filling ratio of the capacitor is at least 75%. In particular, the volume filling ratio refers to the ratio of the volume of the wound element to the volume of the cavity formed by the case and cover.

[0033] According to at least one further embodiment of the capacitor, the anode formation coefficient of the capacitor is up to 1.55. In particular, the anode formation coefficient corresponds to the ratio of the voltage at which the anodic oxide layer is formed to the nominal voltage of the capacitor. For example, the nominal voltage refers to the maximum operating voltage applied between the anode and cathode of the capacitor during operation. In particular, a higher anode formation coefficient results in a longer capacitor lifespan.

[0034] For example, an anode element such as an anode foil includes an anodic oxide layer on its surface, and the formation voltage of the anodic oxide layer corresponds to the thickness of the anodic oxide layer. For example, the formation voltage can be measured by immersing the anode element together with the counter electrode in a liquid electrolyte and applying a constant current to the anode element. The constant current is applied until the voltage between the anode element and the counter electrode saturates to the maximum value corresponding to the formation voltage.

[0035] In particular, the formation voltage is measured in a stainless steel tank acting as the counter electrode at a temperature of 90°C using a liquid electrolyte containing demineralized water, boric acid, and ammonium pentaborate. Also, for example, the area of ​​the anode element is 20 cm². 2 Therefore, the current density of the constant current is 0.5 mA / cm². 2 That is the case.

[0036] According to at least one further embodiment of the capacitor, the nominal voltage of the capacitor is at least 350V.

[0037] According to at least one further embodiment of the capacitor, the gas dissipation element is electrically insulated.

[0038] According to at least one further embodiment of the capacitor, the dielectric strength of the gas dissipation element is at least 1.2 kV / mm.

[0039] Furthermore, this specification describes a method for manufacturing capacitors. In particular, this method can be used to manufacture the capacitors described above. All the characteristics of the capacitors are disclosed in relation to the method for manufacturing the capacitors, and vice versa.

[0040] According to one embodiment of a method for manufacturing a capacitor, a case and a cover are provided, one of which includes at least one through-hole. The case and the cover may each also include at least one through-hole.

[0041] According to a further embodiment of the method for manufacturing a capacitor, at least one through-hole is covered with a gas venting element, which is configured to reduce the gas pressure inside the capacitor during its operation. If the case and cover each contain at least one through-hole, at least two separate gas venting elements may be provided to cover the respective through-holes in the case and cover.

[0042] According to a further embodiment of the method for manufacturing a capacitor, the gas dissipation element is chemically adsorbed onto the outer or inner surface of the case or cover, and the outer or inner surface includes a surface structure configured to improve the bonding between the gas dissipation element and the outer or inner surface.

[0043] In a further embodiment of the method for manufacturing a capacitor, the capacitive element is provided within a case. For example, the capacitive element includes a wound element comprising an anode foil and a cathode foil wound around each other. In particular, the case includes a cavity, and the wound element is inserted into the cavity.

[0044] According to a further embodiment of the method for manufacturing a capacitor, the case is sealed with a cover. For example, the cover is pressed against the case or pressed into the cavity. For example, the cover is pressed into the cavity with a curling tool such that the edges of the case curl toward the cover when the cover is pressed into the cavity. In particular, the cover is pressed against the case or pressed into the cavity such that a liquid-proof seal or an air-proof seal is formed between the case and the cover.

[0045] According to one embodiment, the method for manufacturing a capacitor is: Step a) providing a case and cover, one of which includes at least one through hole, Step b) covering at least one through-hole with a gas release element, wherein the gas release element is configured to reduce the gas pressure inside the capacitor during capacitor operation, and the gas release element is chemically adsorbed to the outer or inner surface of the case or cover, and the outer or inner surface includes a surface structure configured to improve the bond between the gas release element and the outer or inner surface, respectively. Step c) involves providing a capacitive element inside the case, This includes step d) sealing the case with a cover.

[0046] Preferably, the steps of the capacitor manufacturing method are carried out in the order of a) to d) described above.

[0047] According to a further embodiment of the method, the step of covering at least one through-hole includes the step of adhering a gas venting element to the outer or inner surface of the case or cover so as to cover the through-hole. For example, an adhesive is used to adhering the gas venting element to the outer or inner surface of the case or cover.

[0048] According to a further embodiment of the method, the step of covering at least one through-hole includes the step of directly bonding the gas venting element to the outer or inner surface of the case or cover such that the through-hole is completely covered. In particular, no adhesive is used when forming a liquid-tight seal between the outer surface and the gas venting element, or between the inner surface and the gas venting element. For example, a primary bond, a secondary bond, or a van der Waals bond is formed between the gas venting element and the case, or between the gas venting element and the cover.

[0049] According to a further embodiment of the method, the gas diffusion element is a gas diffusion layer that is chemically adsorbed onto the case or cover in the step of covering at least one through-hole. In particular, the gas diffusion layer is bonded to the case or cover by a chemical reaction when it is adsorbed onto the case or cover.

[0050] According to a further embodiment of the method, the step of covering at least one through-hole includes arranging a gas-releasing element in a viscous form across the through-hole, and then curing or solidifying the gas-releasing element. For example, the gas-releasing element consists of a gas diffusion layer containing a resin. For example, the resin is applied to the entire through-hole and cured using heat or ultraviolet light. [Brief explanation of the drawing]

[0051] Further advantageous embodiments and further embodiments of capacitors and methods for manufacturing capacitors will become apparent from the following exemplary embodiments described in relation to the drawings.

[0052] [Figure 1] Figure 1 shows a schematic cross-sectional view of a first capacitor according to a different exemplary embodiment. [Figure 2]Figure 2 shows a schematic cross-sectional view of a second capacitor according to a different exemplary embodiment. [Figure 3] Figure 2 shows a schematic cross-sectional view of a third capacitor according to a different exemplary embodiment. [Figure 4] Figure 4 shows a schematic cross-sectional view of a fourth capacitor according to a different exemplary embodiment. [Figure 5] Figure 5 shows a schematic cross-sectional view of a fifth capacitor according to a different exemplary embodiment. [Figure 6] Figure 6 shows a schematic cross-sectional view of a sixth capacitor according to a different exemplary embodiment. [Modes for carrying out the invention]

[0053] Elements that are identical, similar, or have the same effect are indicated by the same symbol in the figures. The proportions of the figures and the elements shown in the figures are not considered to be to scale. Rather, individual elements may be exaggerated and shown larger for better representation and / or understanding.

[0054] The capacitor 1 in the exemplary embodiment shown in Figure 1 includes a capacitive element 2 housed within a case 3 sealed by a cover 4. The case 3 is cylindrical and made of a metal such as aluminum. For example, the cover 4 is made of rubber. Two conductive elements 10 that electrically contact the capacitive element 2 are embedded in the cover 4.

[0055] Case 3 has a through-hole 5 on its bottom surface opposite to the cover 4. The through-hole 5 is circular in shape with a diameter of 1 mm to 5 mm. The through-hole 5 is covered by a gas release element 6 configured to reduce the gas pressure inside the capacitor 1 during operation. In particular, gases such as H2 generated by the electrochemical process when the capacitive element 2 is charged or discharged during the operation of the capacitor 1 can escape from inside the capacitor 1 through the through-hole 5 and the gas release element 6.

[0056] For example, the gas dissipation element 6 is a gas diffusion layer 6 made of silicone. The gas dissipation element 6 is chemically adsorbed onto the outer surface 7 of the case 3. The outer surface 7 of the case 3 is on the opposite side from the inner surface 8 of the case 3, which faces the capacitive element 2. In particular, for example, the gas dissipation element 6 is not clamped inside the through hole 5. Since no mechanical element is required to clamp the gas dissipation element 6, the total thickness TD of the case 3 and the gas dissipation element 6 can be advantageously reduced. In particular, the total thickness TD of the case 3 and the gas dissipation element 6 is a maximum of 2.5 mm, and the thickness D of the gas dissipation element 6 is 0.1 mm to 2.5 mm.

[0057] Compared to the capacitor 1 described with respect to the exemplary embodiment in Figure 1, the capacitor 1 according to the exemplary embodiment in Figure 2 includes a gas release element 6 provided on the inner surface 8 of the case 3. For example, by providing the gas release element 6 on the inner surface 8 of the case 3, the possibility of the case 3 and the gas release element 6 separating or delamination occurring during the operation of the capacitor 1 can be reduced.

[0058] Compared to the capacitor 1 described with respect to the exemplary embodiment in Figure 1, the capacitor 1 according to the exemplary embodiment in Figure 3 has a through-hole 5 located in a cover 4 rather than a case 3. The gas release element 6 is coupled to the outer surface 8 of the cover 4, which faces away from the capacitive element 2.

[0059] Compared to the capacitor 1 described with respect to the exemplary embodiment in Figure 1, the capacitor 1 according to the exemplary embodiment in Figure 4 has a plurality of through-holes 5 provided on the bottom surface of the case 3. The plurality of through-holes 5 are arranged in a regular pattern. The plurality of through-holes 5 are completely covered by a gas release element 6.

[0060] By providing multiple through-holes 5 within the case 3, the cross-sectional area of ​​each of the multiple through-holes 5 can be reduced compared to a single through-hole 5, while maintaining the overall gas permeability of the multiple through-holes 5. In particular, by providing multiple through-holes 5 within the case, rather than one large through-hole 5, the mechanical stability of the case 3 can be advantageously improved.

[0061] Compared to the capacitor 1 described with respect to the exemplary embodiment in Figure 1, the capacitor 1 according to the exemplary embodiment in Figure 5 has an additional through-hole 5 located within the cover 4 and completely covered by a second gas diffusion element 6.

[0062] Figure 6 shows a portion of the case 3 of a capacitor 1 according to a further exemplary embodiment. Similar to the capacitor 1 described in relation to Figure 1, the capacitor shown in Figure 6 has a through hole 5 provided on the bottom surface of the case 3. In addition, the outer surface 7 of the case has a surface structure 9 in the form of a recess 9 that completely encloses the through hole 5.

[0063] The gas venting element 6 is a gas diffusion layer formed inside the recess 9 so as to completely cover the through hole 5. Furthermore, the gas venting element 6 extends into the through hole 5, completely filling it. The gas venting element 6 is made of silicone chemically adsorbed onto the case 3. Specifically, the gas venting element 6 is formed by placing silicone resin inside the recess 9 and the through hole 5, and then curing it.

[0064] The present invention is not limited to the exemplary embodiments as described above. Rather, the present invention encompasses all new features and all combinations of features, in particular all combinations of features in the claims and all combinations of features in the exemplary embodiments, even if such features or such combinations of features themselves are not expressly described in the claims or exemplary embodiments. [Explanation of Symbols]

[0065] 1 Capacitor 2 Capacitive elements 3 cases 4 Covers 5 Through hole 6. Gas emission elements 7 External surface 7 Inner 9 Surface structure 10 Conductive elements D Thickness TD Total Thickness

Claims

1. A capacitor (1) including a capacitive element (2) provided inside a case (3) sealed by a cover (4), The capacitor (1) comprises a case (3) or a cover (4) including at least one through-hole (5) covered with a gas release element (6) configured to reduce the gas pressure inside the capacitor (1) during operation, wherein the gas release element (6) is provided on the outer surface (7) or inner surface (8) of the case (3) or the cover (4), and the outer surface (7) or inner surface (8) each includes a surface structure (9) configured to improve the bond between the gas release element (6) and the outer surface (7) or inner surface (8), and the gas release element (6) is chemically adsorbed to the case (3) or the cover (4).

2. The capacitor (1) according to the preceding claim, wherein the gas dissipation element (6) includes or consists of a gas diffusion layer.

3. The capacitor (1) according to any one of the preceding claims, wherein the gas dissipation element (6) comprises at least one of a polymer, a metal-organic structure, or a silicon material.

4. The condenser (1) according to any one of the preceding claims, wherein the gas dissipation element (6) extends at least partially into the through hole (5).

5. The capacitor (1) according to any one of the preceding claims, wherein the thickness (D) of the gas dissipation element is 0.1 mm to 2.5 mm.

6. If the case (3) includes the through hole (5), the total thickness (TD) of the case (3) and the gas release element (6) is a maximum of 2.5 mm, or, The capacitor (1) according to any one of the preceding claims, wherein the cover (4) includes the through hole (5), and the total thickness (TD) of the cover (4) and the gas release element (6) is a maximum of 3.5 mm.

7. The capacitor (1) according to any one of the preceding claims, wherein molecules with a molecular weight of less than 60 Da can penetrate the gas release element (6).

8. The case (3) is a capacitor (1) according to any one of the preceding claims, comprising a metal.

9. The capacitor (1) according to any one of the preceding claims, wherein the capacitive element (2) is a wound element containing a liquid electrolyte with a water content of at least 2% by weight.

10. The capacitor (1) according to any one of the preceding claims, wherein the volume filling rate of the capacitor (1) is at least 75%.

11. The capacitor (1) according to any one of the preceding claims, wherein the anode foil formation coefficient of the capacitor (1) is a maximum of 1.

55.

12. The capacitor (1) according to any one of the preceding claims, wherein the nominal voltage of the capacitor (1) is at least 350V.

13. The gas dissipation element is electrically insulated, the capacitor (1) according to any one of the preceding claims.

14. The capacitor (1) according to any one of the preceding claims, wherein the dielectric strength of the gas dissipation element is at least 1.2 kV / mm.

15. Step a) provides a case (3) and cover (4) on one side which include at least one through hole (5), Step b) covering at least one of the through holes (5) with a gas release element (6), wherein the gas release element (6) is configured to reduce the gas pressure inside the capacitor (1) during the operation of the capacitor (1), the gas release element (6) is chemically adsorbed to the outer surface (7) or inner surface (8) of the case (3) or the cover (4), and the outer surface (7) or the inner surface (8) includes a surface structure (9) configured to improve the bond between the gas release element (6) and the outer surface (7) or the inner surface (8), Step c) providing a capacitive element (2) inside the case (3), A method for manufacturing a capacitor (1), comprising step d) sealing the case (3) with the cover (4).

16. The method according to claim 15, wherein in step b), the gas release element (6) is placed across the through hole (5) in a viscous form, and then hardened or solidified.

Images