Capacitor

Abstract

The utility model relates to a capacitor comprising a capacitive element arranged in a housing, in which a gas dissipation element is arranged in or on the housing, and / or in which the capacitor has an electrolyte comprising an organic acid having a pKa of 4.1 or higher, and / or in which the capacitor has an OMS of 20% or higher.

Description

Technical Field

[0001] This application relates to a capacitor and a method of forming such a capacitor. Background Technology

[0002] There is a high demand for capacitors with high volumetric efficiency. This means there is a high demand for increasing capacitance while maintaining capacitor size, or miniaturizing capacitors while maintaining capacitance.

[0003] In this context, the inventors of the present invention have discovered that at least some capacitors with high volumetric efficiency tend to have a shorter lifespan under the same operating conditions as capacitors with lower volumetric efficiency. Summary of the Invention

[0004] Therefore, the object of this application is to provide a capacitor that can have an improved lifespan. According to another object, a capacitor that can have improved volumetric efficiency can be provided.

[0005] The capacitors of each embodiment help to at least partially overcome some of the above-described problems or at least partially contribute to achieving at least one of the above-described objectives.

[0006] Advantageous embodiments are provided in the examples of further embodiments.

[0007] Several features are disclosed below, which, when used individually, can provide the benefits described above or other benefits as described below. However, in particular, synergistic effects and additional benefits can be achieved when they are combined.

[0008] According to an embodiment applicable to all other embodiments described below, a capacitor is described having a capacitor element and a housing, the capacitor element being arranged in the housing.

[0009] According to an embodiment, the capacitor element can be configured to store charge during capacitor operation. For example, the capacitor element can be configured to charge and discharge during capacitor operation. For example, the capacitor element may include a cathode and an anode. The cathode and anode can be electrically contacted through conductive elements (such as wires or leads). The cathode and anode are generally not limited.

[0010] According to an embodiment that may be preferred for use in other embodiments, the capacitor element may be a wound element, wherein the anode and cathode are wound. For example, the wound element may be a cylindrical wound element or a flat wound element.

[0011] According to an embodiment that is also preferred for other embodiments, the capacitor can be an electrolytic capacitor. In this case, the electrolyte is arranged between the anode and the cathode. For example, a separator impregnated or impregnated with the electrolyte can be arranged between the anode and the cathode. The separator is not limited, except that it should be configured to be impregnated or impregnated in the electrolyte and it should not be conductive. The separator can comprise or be composed of a cellulose-based material (such as paper). In an electrolytic capacitor, it may be preferred that the anode has an oxide on its surface that provides at least partial chemical and electrical isolation between the anode and the electrolyte. The electrolyte can have a water content of at least 2 wt%.

[0012] Electrolytic capacitors preferably have a wound element as described above. Specifically, the wound element may include cathode and anode foils wound around each other and separated by a separator impregnated with electrolyte. For example, the capacitor is an aluminum electrolytic capacitor. For example, the wound element is partially or completely immersed in a liquid electrolyte.

[0013] Typically, the anode and cathode are not limited. According to an embodiment, the anode may be an etched anode comprising aluminum or composed of aluminum.

[0014] According to embodiments that are generally preferred for use in various embodiments and particularly for winding elements and / or electrolytic capacitor embodiments, the anode may be a so-called sintered anode. Herein and hereinafter, the term "sintered anode" refers to any anode that includes a sintered portion.

[0015] According to an embodiment, the sintered anode may include valve metal. Preferably, the sintering portion includes one or more valve metals. In this case, one or more different types of valve metal particles are sintered together in the sintering portion.

[0016] The inventors of this invention have discovered that sintering the anode may help increase the volumetric efficiency of the capacitor. In particular, an improved volumetric efficiency can be observed compared to etched electrodes.

[0017] Valve metal is understood in a general technical sense and is not limited thereto. For example, valve metal includes at least aluminum, titanium, tantalum, niobium, tungsten, chromium, zirconium, hafnium, zinc, vanadium, bismuth, or antimony. In particular, aluminum, tantalum, and vanadium are preferred. Aluminum is the most preferred.

[0018] According to an embodiment, the anode can be a sintered block anode, meaning that in this case, most of the volume of the anode can be composed of sintered material. In this case, the sintered material block can be contacted via lead terminals or the like.

[0019] According to embodiments that are preferred or even more preferred than those described herein, the sintered anode may also have a substrate in addition to the sintered portion. This substrate portion comprises a conductive material. In this case, the sintered portion may be disposed on the main surface of the substrate. For example, and preferably, the substrate may be a foil, and the sintered portion may be a sintered layer disposed on the main surface of the foil. Even more preferably, the two opposing main surfaces of the substrate foil may be covered by a sintered layer. This arrangement can allow for a higher specific capacitance of 15% to 30% compared to an etched anode.

[0020] According to an embodiment, the anode (in the case of either etched or sintered anode) has a passivation layer on its surface. This passivation layer may be an oxide layer.

[0021] According to embodiments that may be preferred, but are not limited to, sintered anodes, the average thickness of the anode can be at least 80 μm. The inventors have found that this average thickness helps to provide improved mechanical stability to the anode, which makes handling and manufacturing easier.

[0022] The capacitor housing can accommodate the capacitor element. For example, and preferably, it is configured to mechanically stabilize the capacitor and / or protect the capacitor element from external forces or harmful substances that may damage the capacitor during operation.

[0023] According to an embodiment, the housing may include an outer shell and a cover that encloses the outer shell. For example, the outer shell is configured to mechanically stabilize the capacitor. In particular, the housing includes a cavity for arranging the capacitor element. For example, the housing may have an opening for inserting the capacitor element into the cavity during capacitor manufacturing. The shape of the housing is not limited. For example, the housing may be cylindrical, having a bottom surface and an open end facing the bottom surface, wherein the open end forms an opening. In particular, the housing may be configured to protect the capacitor element from external forces or harmful substances that may damage the capacitor during operation.

[0024] The housing can be configured to electrically insulate the capacitor element from the external environment. Alternatively, the housing can be configured to be in electrical contact with the capacitor element. For example, the housing is conductive and electrically connected to an anode or cathode. Furthermore, the housing can be configured as a heat sink, such that heat generated by the capacitor element during operation is effectively transferred and dissipated from the capacitor element. For example, the capacitor element is in thermal contact with the housing. For example, the housing can include or be composed of a metal (e.g., aluminum). Alternatively or additionally, the housing can include or be composed of, for example, plastic or a polymer.

[0025] For example, the cover and the housing form a sealed cavity in which the capacitor element is disposed. Specifically, the cavity is sealed by arranging or mounting the cover over an opening in the housing. Furthermore, at least one conductive element (such as a wire or lead) for electrical contact with the capacitor element may be disposed in or integrated into the cover. For example, the cover may be made of metal, plastic, glass, cardboard, or rubber, or may be composed of metal, plastic, glass, cardboard, or rubber.

[0026] The inventors of this invention have discovered that gases can form in encapsulated capacitors, and particularly in electrolytic capacitors, during manufacturing or operation. This gas formation can increase the internal pressure of the capacitor, potentially hindering its operation or damaging it, and thus affecting its lifespan. This effect is particularly pronounced in capacitors that typically have high volumetric efficiency, as electrically unused volume can be avoided, which can compensate for gas formation. However, this effect is especially significant for capacitors with sintered anodes. For example, during charging or discharging, electrochemical processes can generate gases such as H2, CO2, methane, ethane, or other low-molecular-weight gases inside the capacitor. Therefore, the internal pressure of the capacitor may increase during operation. If the internal pressure becomes too high, the capacitor may, for example, be damaged or rupture.

[0027] The inventors of this invention believe that sintered anodes are particularly prone to cracking within or on the sintered body. They believe such cracking may be due to mechanical stress, such as during production (e.g., winding of winding elements). This can lead to cracks visible to the naked eye. Furthermore, thermal stress (e.g., due to temperature changes) can also cause cracking. The inventors have observed that sintered anodes appear to be more sensitive to thermal stress. Freezing and thawing of the electrolyte can also lead to additional cracking.

[0028] The inventors observed that the increased gas formation may be related to the aforementioned cracks in some way. Their theory is that the cracks are reaction zones where gas can form, for example, due to chemical reactions. The inventors believe that chemical or electrochemical processes can generate gas at the crack locations, both in the absence of applied voltage and during voltage-bearing operation. Furthermore, the cracks appear to increase leakage current, which could also contribute to gas formation. Additionally, the presence of the cracks appears to make the electrode more sensitive to aqueous electrolytes.

[0029] According to an embodiment, a gas dissipation element is arranged inside or on the housing. The gas dissipation element is configured to reduce the gas pressure within the capacitor. For the reasons stated above, having a gas dissipation element is generally useful in capacitors with high volumetric efficiency (but particularly in capacitors with sintered anodes). The gas dissipation element can be configured to immediately reduce the gas pressure within the capacitor when the capacitor is sealed or otherwise hermetically sealed. This can occur after a sealing step during production (such as when the housing is closed with a lid in the example above). Even more relevantly, the gas dissipation element can be configured to reduce the gas pressure within the capacitor during operation.

[0030] Preferably, under normal operating conditions, the gas dissipation element is configured to reduce gas pressure in a non-destructive manner rather than through a destructive burst pressure release system.

[0031] Specifically, a gas can be generated within the housing during capacitor operation. This gas can escape from the housing through a gas dissipation element. For example, if the partial pressure of the gas inside the cavity is greater than the partial pressure of the gas outside the cavity, the gas can diffuse or permeate out of the housing through the gas dissipation element. The gas dissipation element can preferably be configured such that liquids (such as electrolytes) cannot permeate or diffuse through the gas dissipation element as easily as gases. More preferably, the gas dissipation element is configured such that no electrolyte can permeate through it during the technically relevant time period. In other words, in this case, the liquid can be tightly sealed, for example, within the housing.

[0032] According to a modification of the previous embodiment, the gas dissipation element can be placed in or above a through-hole in the housing. The through-hole can be formed in the wall of the housing. Here and throughout the application, the term "wall" is not limited to a side wall, but can also be a bottom wall or a top wall. Generally, the location of the through-hole and, correspondingly, the location of the gas dissipation element, is not limited. Furthermore, more than one gas dissipation element can be implemented in this manner in a capacitor. Generally, the through-hole can be any type of opening that forms a connection between the interior and exterior of the housing. Specifically, the through-hole can be a hole or opening that completely penetrates the housing. The through-hole can have any shape.

[0033] According to an embodiment, if the capacitor has a winding element, it may be preferable to arrange the gas dissipation element on the top or bottom side of the housing facing the winding element. The top or bottom side of the winding element can be understood as the side exposing the edge of the winding foil. In this configuration, gas formed in the roll can be discharged from the roll toward the edge of the winding foil and can be effectively discharged from the housing through the gas dissipation element.

[0034] According to an embodiment, if the gas dissipation element is placed in a through-hole in the housing, a portion of the gas dissipation element protrudes into the opening. This can have the advantage of making it easier to anchor the gas dissipation element in the housing in a mechanically stable manner.

[0035] In this case, according to an embodiment, a portion of the gas dissipation element may protrude beyond the opening, and either internally, but more preferably externally, protruding beyond the surface level of the inner or outer surface of the housing.

[0036] According to a preferred embodiment, the gas dissipation element may be flush with the housing, at least inside or outside the housing. More preferably, the gas dissipation element may be flush with both the inside and outside of the housing. The advantage of being flush with the inside of the housing is that the gas dissipation element does not reduce the internal volume of the housing. This unoccupied internal volume can be filled by a winding element, thereby improving volumetric efficiency, or it can act as a buffer volume to reduce the impact of generated gas. Being flush with the outside of the housing simplifies the external profile of the capacitor, making it easier to integrate into applications. Furthermore, this can help avoid protrusions on the outside of the housing, which, for example, could be jammed by sharp or protruding external objects during capacitor installation, potentially damaging the housing or the gas dissipation element.

[0037] According to an embodiment, if the gas dissipation element is placed above a through-hole in the housing, this may mean that a portion of the gas dissipation element is not arranged within the through-hole. In this case, this portion of the gas dissipation element may be arranged on the outer or inner surface of the housing or cover, and above the through-hole.

[0038] Here, and elsewhere in this document, the inner surface is the surface facing the capacitor element, while the outer surface is the surface opposite the inner surface. Specifically, neither the outer nor the inner surface includes the sidewalls of the through-hole.

[0039] Specifically, in the preceding embodiments, the gas dissipation element may partially or preferably completely cover the through-hole. Similarly, the gas dissipation element may cover multiple through-holes in the housing that are close to each other. For example, the gas dissipation element may cover one, two, or more through-holes, or any number of through-holes. For example, the gas dissipation element may completely cover the array of through-holes. For example, the gas dissipation element may be directly arranged or disposed on or above at least one through-hole.

[0040] According to an embodiment, the contact surface of the housing wall includes a surface structure configured to improve the bonding between a portion of the gas dissipation element in contact with the contact surface and the contact surface. In this case, the gas dissipation element is chemisorbed onto the housing. This mode of bonding or attaching the gas dissipation element to or onto the housing is advantageous because it allows for the formation of a mechanically stable connection.

[0041] According to embodiments where the gas dissipation element is at least partially arranged within the through-hole, a portion or all of the surface structure can be established on the surface portion of the through-hole, i.e., on the through-hole wall within the housing wall. According to embodiments, it is preferable that the entire inner circumference of the through-hole has the surface structure. This may, but does not necessarily, mean that the entire surface of the through-hole has the surface structure, but rather that preferably at least one closed-loop region of the inner surface of the through-hole has the surface structure. This helps ensure a complete seal of the through-hole.

[0042] According to an embodiment, the through-hole may have a stepped structure, which has at least one step. By having a stepped structure, the surface area of ​​the structured contact surface of the through-hole can be increased.

[0043] According to an embodiment of the gas dissipation element, in this embodiment, the gas dissipation element is placed above a through-hole, and a surface structure can be formed on the inner or outer surface of the housing. For example, in this case, the surface structure can completely surround the through-hole. For example, the surface structure includes a surface region with increased surface roughness. For example, the surface structure includes one or more recessed portions or is composed of one or more recessed portions. In particular, the recess can completely surround the through-hole, or the through-hole can be formed inside the recess. For example, the depth of the recess is at most half the thickness of the housing or cover.

[0044] According to another embodiment of the capacitor, the gas dissipation element can be chemically adsorbed onto the housing. For example, in this case, no adhesive is used to attach the gas dissipation element to the housing. Specifically, a direct chemical bond can be formed between the gas dissipation element and the housing, thereby forming a liquid-tight seal. The chemical bond can be, for example, a primary bond (such as a covalent bond, ionic bond, or metallic bond) or a secondary bond (such as a dipole-dipole interaction, hydrogen bond, or van der Waals bond).

[0045] Compared to gas dissipation elements that are mechanically clamped within a through-hole, gas dissipation elements with chemisorption mean that the manufacturing process can be simplified by arranging the gas dissipation elements to seal the through-hole, thereby reducing production costs. Furthermore, the overall thickness of the housing and the gas dissipation element can be advantageously reduced because, for example, a component for clamping the gas dissipation element may not be necessary.

[0046] According to embodiments of the capacitor, the gas dissipation element may include or be composed of a gas diffusion layer. Specifically, gas generated inside the capacitor during operation may diffuse or permeate through or diffuse within the gas diffusion layer. The gas permeability of the gas dissipation element to H2 is preferably, for example, between 10 and 10. 10 cm 2 / (s×atm) and 10 13 cm2 Between / (s×atm).

[0047] According to a further embodiment of the capacitor, the gas dissipation element may include or be composed of at least one of the following materials: polymer, metal-organic framework, or silicon. For example, the gas dissipation element includes or is composed of a gas diffusion layer, wherein the latter includes or is composed of: such as polymer, silicone, metal-organic framework, silicon, silicon nitride, or silicon carbide.

[0048] According to a further embodiment of the capacitor, the thickness of the gas dissipation element can be between 0.1 mm and 2.5 mm, including 0.1 mm and 2.5 mm. The thickness of the gas dissipation element can also be between 0.1 mm and 3 mm, including 0.1 mm and 3 mm. For example, the thickness of the gas diffusion layer is between 0.1 mm and 2.5 mm, including 0.1 mm and 2.5 mm. Specifically, thickness refers to the spatial dimension in the direction parallel to the through-hole. In other words, thickness refers to the spatial dimension in the direction parallel to the central axis of the through-hole.

[0049] According to a further embodiment of the capacitor, the total thickness of the housing wall and the gas dissipation element can be a maximum of 2.5 mm. Specifically, this total thickness can refer to the combined thickness of the gas dissipation element and the housing. This is particularly preferred when a through-hole is established in the housing.

[0050] According to a further embodiment of the capacitor, the total thickness of the housing and the gas dissipation element can be a maximum of 3.5 mm. Specifically, the total thickness can refer to the combined thickness of the gas dissipation element and the cover. This is particularly preferred when a through-hole is established in the housing.

[0051] According to a further embodiment, the gas dissipation element is configured to allow molecules with a molecular weight less than 60 Da (unit: Dalton; equal to atomic mass unit u) to pass through it. Specifically, H2 can penetrate or permeate through the gas dissipation element.

[0052] According to another embodiment, the gas dissipation element may have an active portion configured to reduce the gas pressure inside the capacitor and a passive portion configured to provide a mechanical connection between the housing and the active portion. This simplifies the manufacture or installation of the gas dissipation element because the function of establishing contact or connection with the housing is separate from the function of allowing gas to diffuse or permeate out of the housing. The above description of the gas dissipation element can be applied to the active portion in the same manner, wherever applicable. In particular, the active portion may include the materials defined above for the gas dissipation element. The passive portion may include or consist of any of the following: silicone resin, acrylate resin, polyurethane resin, synthetic rubber, natural rubber, latex, fluoropolymer. However, in a general sense, the active portion is not necessarily made of a different material than the passive portion. In the most general sense, the active and passive portions refer only to the functions described above. These can be achieved by different materials or by different portions based on shrinkage or geometry.

[0053] According to an embodiment, the active portion of the gas dissipation element can be cylindrical. This shape may be advantageous in manufacturing.

[0054] According to an embodiment, the active portion of the gas dissipation element can be configured to irreversibly rupture from or irreversibly disconnect from the passive portion in the event of a pressure increase that cannot be compensated for by the non-destructive pressure reduction capability of the gas dissipation element. This has the advantage that the gas dissipation element constructed in this way can non-destructively reduce pressure, and if a sudden pressure increase cannot be compensated for by the aforementioned diffusion- or permeation-based mechanisms, it can also rupture and prevent high-pressure buildup, which could not only damage the capacitor but also other components in the device that houses the capacitor, or other components that could otherwise pose a hazard. Therefore, a gas dissipation element constructed in this manner can supplement or even replace the function of a separate emergency pressure relief system.

[0055] According to another embodiment, the silicon (element symbol Si) portion in the gas dissipation element can be 5 wt% or higher. Similarly, in the case where the gas dissipation element has active and passive portions, the silicon portion in the active portion can be 5 wt% or higher. The inventors of the present invention have discovered that when the gas dissipation element or the active portion has a silicon portion higher than 5 wt%, gas dissipation can be increased and pressure can be reduced more quickly. This is particularly important for both the active and passive portions because the active volume is reduced here compared to the case where the entire gas dissipation element has active properties. This reduced active volume can be at least partially compensated by having said amount of silicon.

[0056] According to an embodiment, the active volume of the gas dissipation element or the volume of the active portion of the gas dissipation element can be 0.05 mm. 3Or higher. The inventors unexpectedly discovered that, utilizing the active volume, the formed gas could be effectively transported out of the casing. More preferably, the active volume is 0.055 mm. 3 Or higher, or even 0.058mm 3 Or even higher. This even improves upon the advantages mentioned above.

[0057] According to embodiments that can be combined with, but are not limited to, embodiments having gas dissipation elements, at least a portion of the capacitor element is impregnated or submerged in an electrolyte. Furthermore, the electrolyte comprises an organic acid having a pKa of 4.1 or higher. Here, the organic acid can be any acid that is considered an organic molecule in a general chemical understanding. The organic acid can be, in particular, an organic Brønsted acid. Acids. "4.1 or higher pKa" can be understood as acids with a proton or lower acidic proton having a pKa of 4.1. Of course, the statement "electrolytes include organic acids having a pKa of 4.1 or higher" can mean that the electrolyte includes one or more organic acids having a pKa of 4.1 or higher. The inventors have found that pKas of 4.2 or higher, 4.3 or higher, 4.4 or higher, or 4.5 or higher can also effectively help suppress gas formation.

[0058] The inventors of this invention have discovered that organic acids with a pKa of 4.1 or higher help reduce leakage current and gas formation rate. This is particularly important for sintered anodes, especially aluminum-containing sintered anodes. This may also be particularly advantageous for other aluminum-containing anodes. This method can synergistically complement the embodiments described above with gas dissipation elements. The inventors believe that organic acids may help passivate cracks. The inventors believe that the acid helps form oxides on the exposed metal of the crack. Furthermore, the inventors believe that by making the pKa 4.1 or higher, the acid is not too strong and is unlikely to cause unwanted side reactions. The inventors believe that at a pKa of 4.1 or higher, the acid is too weak to dissolve the metal of the electrode, but strong enough to passivate cracks.

[0059] Regarding the mechanism, the inventors believe that acids with low pKa values ​​readily transform into ions through deprotonation, resulting in high ion density on the surface. They suggest that this may lead to side reactions and potentially oxide decomposition when the applied voltage increases. Conversely, acids with higher pKa values ​​create crystalline oxide layers with low leakage current and high dielectric strength.

[0060] According to embodiments, the pKa range of the organic acid is preferably 4.1 ≤ pKa ≤ 5.5. The inventors have found that an upper limit of 5.5 helps to more effectively reduce gas formation compared to pKa values ​​higher than 5.5. The inventors believe that acids falling within the pKa range defined herein possess a certain acidity that is advantageously neither too acidic nor too weak; that is, an upper limit of 5.5 helps to make the acid more likely to be strong enough to help passivate cracks. The inventors have found that, with pKa upper limits of 5.2, 5.1, or 5.0, the suppression of gas formation can be reduced even more effectively.

[0061] According to embodiments, the organic acid can be a carboxylic acid, wherein the pKa of the proton of the carboxylic acid is 4.1 or higher, or falls within the aforementioned pKa range. The inventors have found that carboxylic acids can provide the aforementioned properties and are unlikely to cause unwanted side reactions.

[0062] According to examples, the organic acid can be at least a dicarboxylic acid having a pKa1 of 4.1 or higher. The term "at least a dicarboxylic acid" includes all individual dicarboxylic acids and carboxylic acids with more carboxyl groups. The latter can be referred to as polycarboxylic acids. "pKa1" represents the pKa value of the first deprotonation reaction in a base titration. The above properties can be applied to pKa1 al, such as in examples specifically concerning the range.

[0063] According to embodiments, linear dicarboxylic acids can be used, wherein multiple carbon atoms having arbitrary substituents are arranged between acid groups. For example, and preferably, the groups between the acid groups can be methylene (-CH2-). For example, the dicarboxylic acid can have HOOC-(CH2). n -COOH structure. n can in principle be any natural number, including 0. More preferably, n is greater than or equal to 4. The inventors have found that having at least four methylene groups between the carboxyl groups helps the second proton also maintain sufficient acidity to support the suppression of gas formation. For example, dicarboxylic acids are not limited to, but can be, adipic acid, octanoic acid, azelaic acid, sebacic acid, undecanoic acid, dodecanoic acid, and tridecanoic acid. The pKa1 values ​​of these can be used in place of the given ranges above.

[0064] According to the examples, esters of at least dicarboxylic acids may be used, wherein one carboxylic acid group is retained. The pKa values ​​defined above also apply to these. For example, esters of the dicarboxylic acids listed above may be used.

[0065] According to other embodiments, dimer acids (i.e., polymeric unsaturated fatty acids) or trimer acids (i.e., polymeric unsaturated fatty acids) can be used. The pKa values ​​defined above can also be applied to these.

[0066] According to the embodiments, the concentration of the organic acid can be at least 0.1 wt%. This can mean that the concentration of one organic acid with a pKa of 4.1 or higher is at least 0.1 wt%. This can also mean that the concentration of all organic acids present in the electrolyte with a pKa of 4.1 or higher is at least 0.1 wt%. The latter is preferred. This concentration range is particularly preferred for carboxylic acids, and even more preferred for at least dicarboxylic acids or the aforementioned esters. The inventors have found that a concentration of 0.1 wt% or higher helps to improve the suppression of gas formation. The inventors believe that this concentration helps to effectively oxidize cracks.

[0067] According to the embodiments, the upper limit of the concentration range of at least dicarboxylic acid can be 12 wt%. The above-mentioned advantages are observed in the range of 0.1 wt% to 12 wt%, and negative effects are unlikely to occur.

[0068] According to embodiments, the electrolyte may include a polyol. Even more preferably, the main component of the electrolyte is a polyol. The inventors have found that by containing a polyol in the electrolyte, the gas formation suppression effect of the acid described above can be particularly preferred. A preferred example of a polyol is ethylene glycol.

[0069] According to another embodiment, another capacitor comprising a capacitive element arranged in a housing is described. In this capacitor, the volume occupied by the anode is 20% or higher relative to the total volume within the housing. This volume portion may be referred to as the occupied anode metal space, abbreviated as "OMS". The inventors have found that volumetric efficiency can be improved by having an OMS of 20% or higher. This advantage can be combined synergistically with other embodiments described herein. However, the inventors have found that an OMS higher than 20% may affect the capacitor's lifespan. The inventors speculate that an OMS higher than 20% may reduce the buffer volume that can compensate for gas formation. Therefore, in this case, applying the measures described above to extend the capacitor's lifespan may be advantageous.

[0070] The inventors discovered that in some cases where OMS exceeds 20%, the maximum lifespan of a capacitor at 105°C may be limited to 2000 hours. The measures described above may help achieve a longer capacitor lifespan. In certain applications requiring a minimum lifespan exceeding, for example, 2000 hours, this could allow the use of capacitors with OMS exceeding 20%.

[0071] According to another embodiment, a method for manufacturing a capacitor is provided. The capacitor described above can be manufactured by this method. The aforementioned properties and advantages may apply. The method includes providing a housing. The properties of the housing described above may apply. The housing has a through-hole. In this case, this opening may be referred to as a first opening. The housing here includes an outer shell and a cover.

[0072] Furthermore, the method includes arranging a gas dissipation element in or above a through-hole or first opening. This can have the aforementioned properties. The gas dissipation element is chemisorbed onto a contact surface of the housing. The contact surface includes a surface structure configured to improve the bonding between the housing and the gas dissipation element. As a further step, a capacitor element having an anode is arranged in the housing, the anode comprising a sintered valve metal. Additionally, before or after arranging the capacitor element in the housing, the capacitor element is impregnated with or immersed in an electrolyte. The capacitor element is sealed within the housing by placing a cap over a cap opening in the housing. The cap opening can be a second opening configured to be closed by the cap.

[0073] According to embodiments of the method, the step of arranging the gas dissipation element in or above the through-hole or the first opening may include bonding the gas dissipation element housing. For example, an adhesive may be used to bond the gas dissipation element to the housing.

[0074] According to another embodiment of the method which may be added to or replace the application of the previous embodiments, the step of arranging the gas dissipation element in or above the through-hole or first opening may include directly bonding the gas dissipation element to the housing. Specifically, no adhesive is used here to form a liquid-tight seal between the housing and the gas dissipation element. For example, primary, secondary, or van der Waals bonds are formed between the gas dissipation element and the housing or between the gas dissipation element and the cap.

[0075] According to another embodiment of the method, during the step of arranging the gas dissipation element in or above the through-hole or first opening, the gas dissipation element can be chemically adsorbed onto the housing. Specifically, in this case, a chemical reaction can bond the gas diffusion element to the housing.

[0076] According to another embodiment of the method, the step of arranging the gas dissipation element in or above the through-hole or the first opening may include arranging the gas dissipation element in an viscous form in or above the through-hole or the first opening, and subsequently curing or hardening the gas dissipation element. For example, in this case, the gas dissipation element may include a gas diffusion unit, such as a layer comprising a resin. For example, the resin is applied and subsequently cured using heat or ultraviolet radiation. Attached Figure Description

[0077] Further advantageous embodiments and methods for producing capacitors will become apparent from the exemplary embodiments described below in conjunction with the accompanying drawings. However, the invention is not limited to these exemplary embodiments. Furthermore, the embodiments are depicted at least in part in the schematic drawings. These schematic drawings are not to scale, and absolute and relative dimensions may be depicted in a distorted manner. Instead, individual elements may be shown exaggeratedly for better representation and / or better understanding. Therefore, absolute or relative dimensions cannot be derived from the schematic depictions unless otherwise stated. Identical, similar, or identical elements are indicated by the same reference numerals in the drawings.

[0078] Figure 1 A schematic cross-section of a first exemplary embodiment of the capacitor is shown.

[0079] Figure 2 A schematic cross-section of a second exemplary embodiment of the capacitor is shown.

[0080] Figure 3 A schematic cross-section of a third exemplary embodiment of the capacitor is shown.

[0081] Figure 4 A schematic cross-section of a fourth exemplary embodiment of the capacitor is shown.

[0082] Figure 5 A schematic cross-section of a fifth exemplary embodiment of the capacitor is shown.

[0083] Figure 6 A schematic lower cross-section of a sixth exemplary embodiment of the capacitor is shown.

[0084] Figure 7 A lower schematic cross-section of a seventh exemplary embodiment of the capacitor is shown.

[0085] Figure 8 A schematic cross-section of the emergency venting operation of a seventh exemplary embodiment of the capacitor is shown.

[0086] Figure 9 A top view of the capacitor's individual emergency vent is shown.

[0087] Figure 10 It shows Figure 9 A schematic cross-section of the capacitor's individual emergency vent shown.

[0088] Figure 11 It shows Figure 9 and 10 The diagram shows a schematic cross-section of the emergency venting action of the capacitor's individual emergency vent. Detailed Implementation

[0089] according to Figure 1 The capacitor 1 of the first exemplary embodiment shown includes a capacitor element 2 disposed in a housing consisting of an outer casing 3 sealed with a cover 4. The outer casing 3 has a cylindrical shape and is made of a metal (such as aluminum). The cover 4 is made of, for example, rubber. Furthermore, two conductive elements 10 for electrical contact with the capacitor element 2 are embedded in the cover 4.

[0090] The capacitor 1 shown here is an electrolytic capacitor. Capacitor element 2 is a wound element, wherein the anode, cathode, and separator are wound into a roll. The anode is a sintered anode, which has sintered aluminum particle layers on both sides of the aluminum foil substrate. Compared to etched foil, the sintered anode can provide improved specific capacitance.

[0091] Although not explicitly depicted, the winding element is wound such that the flat surface faces the cylindrical sidewall of the housing 3, while the edge of the winding foil faces the bottom of the housing 3 and the cover 4. This allows gas to migrate more easily to the bottom or cover, as the flat surface of the winding foil does not impede gas migration.

[0092] The electrolyte is primarily composed of ethylene glycol. In addition, the electrolyte contains dicarboxylic acids with pKa1 between 4.1 and 5.0, such as adipic acid, octanoic acid, azelaic acid, sebacic acid, undecanoic acid, dodecanoic acid, and tridecanoic acid. The total concentration of all dicarboxylic acids satisfying 4.1 ≤ pKa1 ≤ 5.0 ranges from 0.1 to 12 wt%.

[0093] The outer casing 3 has a through-hole 5 in its bottom surface opposite the cover 4. The through-hole 5 penetrates the cover. The through-hole 5 has a circular shape and a diameter between 1 mm and 5 mm. The through-hole 5 is covered by a gas dissipation element 6, which is configured to reduce the gas pressure inside the capacitor 1 during operation. Specifically, during operation of the capacitor 1, gases (such as H2) generated by electrochemical processes during the charging or discharging of the capacitor element 2 can escape from the inside of the capacitor 1 through the through-hole 5 and the gas dissipation element 6. Since the through-hole 5 and the gas dissipation element 6 are arranged in the bottom of the outer casing 3, as described above, gas can easily migrate to the gas dissipation element due to the orientation of the winding element and the bottom relative to each other.

[0094] The occupied anode metal space (abbreviated as "OMS"; the proportion of the volume occupied by the anode relative to the total volume within the housing) is 20% or higher. This achieves optimal volumetric efficiency.

[0095] In this first exemplary embodiment, the gas dissipation element 6 is a gas diffusion layer 6 composed of, for example, silicone resin. The gas dissipation element 6 is chemisorbed onto the outer surface 7 of the housing 3. The chemisorbed portion is formed by roughening the surface of that portion. The outer surface 7 of the housing 3 faces the inner surface 8 of the housing 3, wherein the inner surface 8 faces the capacitor element 2. In particular, for example, the gas dissipation element 6 is not clamped within the through hole 5. Since no mechanical components for clamping the gas dissipation element 6 are required, the total thickness TD of the housing 3 and the gas dissipation element 6 can be advantageously reduced. Specifically, the total thickness TD of the housing 3 and the gas dissipation element 6 is at most 2.5 mm, while the thickness D of the gas dissipation element 6 is between 0.1 mm and 2.5 mm. The volume of the gas dissipation element 6 is 0.058 mm. 3 Or higher.

[0096] The arrangement of the gas dissipation element 6 outside the housing allows for a free internal volume inside the housing, which can be used to increase the winding element and thus increase volumetric efficiency, or it can be used as a buffer volume that can compensate for gas formation in addition to the compensating properties of the gas dissipation element 6.

[0097] In addition to the following differences Figure 2 The second exemplary embodiment shown is the same as the first exemplary embodiment. Compared with the first exemplary embodiment, Figure 2 The capacitor 1 of the second exemplary embodiment includes a gas dissipation element 6 disposed on the inner surface 8 of the housing 3. By disposing the gas dissipation element 6 on the inner surface 8 of the housing 3, the probability of debonding or delamination of the housing 3 and the gas dissipation element 6 during operation of the capacitor 1 can be reduced.

[0098] In addition to the following differences Figure 3 The third exemplary embodiment shown is the same as the first exemplary embodiment. Compared with the first exemplary embodiment, Figure 3 The capacitor 1 in the third exemplary embodiment has a through-hole 5 disposed in the cover 4 instead of in the housing 3. A gas dissipation element 6 is bonded to the outer surface 8 of the cover 4 opposite to the capacitor element 2. Furthermore, this orientation allows the formed gas to easily migrate to the dissipation element 6.

[0099] In addition to the following differences Figure 4 The fourth exemplary embodiment shown is the same as the first exemplary embodiment. Compared to the first exemplary embodiment, according to... Figure 4 The capacitor 1 in the fourth exemplary embodiment has a plurality of through holes 5 arranged in the bottom surface of the housing 3. The plurality of through holes 5 are arranged in a regular array. The plurality of through holes 5 are completely covered by the gas dissipation element 6.

[0100] By arranging multiple through holes 5 in the housing 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 arranging multiple through holes 5 in the housing instead of a larger single through hole 5, the mechanical stability of the housing 3 can be advantageously improved.

[0101] Figure 5 The fifth exemplary embodiment shown has a combination of the properties of the first and third exemplary embodiments. (Regarding...) Figure 1 Compared to the capacitor 1 described in the exemplary embodiments, according to Figure 5 In an exemplary embodiment, the capacitor 1 has an additional through-hole 5 arranged in the cover 4, which is completely covered by the second gas diffusion element 6.

[0102] Figure 6 The lower portion of the sixth exemplary embodiment is shown. This can replace the lower portion in any of the exemplary embodiments described above. Here, the gas dissipation element 6 is completely disposed within the through-hole 5. Furthermore, the through-hole 5 has a stepped profile. This is achieved by having a first through-hole portion 5a and a second through-hole portion 5b. The first through-hole portion is a cylindrical hole with the dimensions defined above for a through-hole according to the first exemplary embodiment. The second through-hole portion 5b is a recess with a diameter wider than the first through-hole portion 5a. As depicted, the second through-hole portion may have a tapered edge, but this is not necessary in this embodiment. The second through-hole portion 5b is a centrally symmetrical portion of a cone and is oriented centrally symmetrically with respect to the cylindrical first through-hole portion 5a. The second through-hole portion 5b may also have a cylindrical profile. This stepped profile can be considered as a surface structure.

[0103] The gas dissipation element has a shape complementary to the through-hole 5 and is completely disposed within the through-hole 5. It is flush with both the inner surface 8 and the outer surface 7 of the cover 3. This has the advantage of maximizing the internal volume and having no protruding edges on the outside of the housing.

[0104] At least the horizontal surface of the recessed second through-hole portion can be roughened to have a surface structure. The gas dissipation element can be chemically adsorbed into the through-hole, and particularly onto the horizontal surface of the second through-hole portion 5b of the through-hole.

[0105] This configuration can, of course, replace, such as... Figure 3 Or the configuration shown in 5, wherein the gas dissipation element is implemented on one side of the cover.

[0106] Figure 7The lower part of the seventh exemplary embodiment is shown. This can replace the lower part in any of the exemplary embodiments described above. This configuration is substantially the same as the configuration described for the sixth exemplary embodiment. However, the gas dissipation element 6 has an active portion 6a and a passive portion 6b.

[0107] The active portion 6a is realized in the first through-hole portion 5a and has its dimensions, but extends through the entire thickness of the gas dissipation element 6. The passive portion 6b is established above the horizontal surface of the recessed second through-hole portion 6b. The passive portion 6b is chemisorbed onto said horizontal surface. Furthermore, the passive portion 6b provides a mechanical connection that holds the active portion 6a in place. Typically, the active and passive portions can be made of the same material, and their functions can be defined by the arrangement of the portions in the through-hole 5.

[0108] Alternatively, the active portion 6a and the passive portion 6b can be made of different materials. In this case, the active portion can be composed of Si. The passive portion 6b can be composed of silicone resin. Other preferred materials may be acrylate resin, polyurethane resin, synthetic rubber, natural rubber, latex, or fluorinated polymer. In this case, the passive portion 6b can be fixed to the housing 3 by vulcanization, overmolding, or chemical bonding. The active portion can be bonded to the passive portion with polymer adhesive.

[0109] Figure 8 A schematic cross-section of the emergency venting action of a seventh exemplary embodiment of the capacitor is shown. The connection between the passive portion 6b and the active portion 6a can be relatively weak and is designed to withstand normal noncritical pressure buildup caused by slow gas formation. This slow gas formation can be compensated for by the non-destructive gas release function of the gas dissipation element. However, in the event of a sudden large accumulation of gas within the housing, the gas may not be able to leave through the gas dissipation element quickly enough by diffusion or permeation, and a dangerous pressure may build up. In this case, the connection between the active portion 6a and the passive portion 6b can be designed to rupture, and an irreversible emergency venting can occur, as indicated by the gas plume 11. Thus, the capacitor is destroyed, but other components or personnel are protected.

[0110] exist Figures 9 to 11 A separate emergency gas release vent 12 is shown. It can be implemented as a thinned area within the housing. In addition to... Figure 7 and Figure 8 In addition to the above setup, the exhaust port can also be constructed. However, more preferably, according to Figure 7 and Figure 8 This configuration can help reduce the need for an additional emergency gas release vent 12. For example... Figure 11As can be seen, the additional emergency gas release vent 12 can also be designed to release suddenly accumulated pressure in a destructive manner, as indicated by a ruptured valve and gas plume 11.

[0111] refer to

[0112] 1 capacitor

[0113] 2 capacitor components

[0114] 3. Outer shell

[0115] 4 lids

[0116] 5 through holes

[0117] 5a First through hole section

[0118] 5b Second Through Hole Section

[0119] 6 Gas dissipation elements

[0120] 6a Active Part

[0121] 6b Passive Part

[0122] 7. Outer surface

[0123] 8 Inner Surface

[0124] 10 conductive elements

[0125] 11 Gas plumes

[0126] 12 separate emergency gas release vents

[0127] D thickness

[0128] TD total thickness

Claims

1. A capacitor comprising a capacitive element disposed in a housing, wherein The capacitor element has an anode comprising sintered valve metal. At least a portion of the capacitor element is impregnated with or submerged in an electrolyte. Gas dissipation elements are arranged in or on the housing. The gas dissipation element is configured to diffuse or permeate gas out of the housing when the partial pressure of the gas inside the housing is greater than the partial pressure of the gas outside the housing. The gas dissipation element is also configured to prevent the electrolyte from permeating through. The gas dissipation element has an active portion and a passive portion, the passive portion providing a mechanical connection between the housing and the active portion, wherein the active portion and the passive portion form a stepped profile, and the diameter of the passive portion is wider than that of the active portion, and the active portion of the gas dissipation element is configured to irreversibly rupture from or irreversibly disconnect from the passive portion in the event of a pressure increase that cannot be compensated by the non-destructive pressure reduction capability of the gas dissipation element.

2. The capacitor of claim 1, wherein the volume occupied by the anode is 20% or more of the total volume within the housing.

3. The capacitor according to claim 1 or 2, wherein the volume of the active portion of the gas dissipation element is 0.05 mm². 3 Or higher.

4. The capacitor of claim 1, wherein the active portion of the gas dissipation element is cylindrical.

5. The capacitor according to claim 1 or 2, wherein the valve metal is Al or includes Al.

6. The capacitor according to claim 1 or 2, wherein the average thickness of the anode is at least 80 μm.

7. The capacitor according to claim 1 or 2, wherein, The gas dissipation element is disposed inside or on the housing such that the contact surface of the housing includes a surface structure that bonds the portion of the gas dissipation element in contact with the contact surface and the contact surface, and wherein the gas dissipation element is chemically adsorbed onto the housing.

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