Battery cell

Abstract

The invention relates to a battery cell (14) having a battery housing (26), in which a plurality of electrodes (20) are arranged. According to the invention, the cell housing (26) has an opening (28) which is covered by a gas-permeable membrane (30), the membrane (30) being covered on the outside by a covering element (34) in order to limit the entry of material into the cell housing (26).

Description

[0001] The invention relates to a battery cell. The battery cell has a battery housing in which a plurality of electrodes are arranged.

[0002] Motor vehicles are increasingly being driven at least partially by means of electric motors, so that they are designed as electric vehicles or hybrid vehicles. For energizing the electric motors, a high-voltage battery is usually used, which comprises a plurality of individual battery modules. The battery modules are usually structurally identical to one another and are electrically connected in series and / or in parallel with one another, so that the voltage applied to the high-voltage battery corresponds to a multiple of the voltage provided by means of each of the battery modules. Each battery module in turn comprises a plurality of battery cells, which are usually arranged in a common module housing and are electrically connected in series and / or in parallel with one another.

[0003] Each of the battery cells usually includes a plurality of galvanic cells. The galvanic cells each have two electrodes, namely an anode and a cathode, and a spacer arranged between them and an electrolyte with freely movable carriers. As such an electrolyte, a liquid is used, for example. In an alternative, the battery cell is designed as a solid-state battery and the electrolyte exists as a solid. The anode and cathode constituting the electrodes of the battery cell usually include a carrier that acts as a current collector. The active material is usually fastened to the carrier, and the active material is a component of a layer applied to the carrier, which is also referred to as a collector. In this case, it is possible that the electrolyte is already present in the layer, or that the electrolyte is introduced later. However, the active material is at least suitable for absorbing working ions, such as lithium ions. Depending on the use as an anode or cathode, different materials are used for the carrier and different types of materials of the layer are used.

[0004] In order to protect the galvanic cell, the galvanic cell is usually arranged in the battery housing of the battery cell, which is sometimes also called a battery cup (Zellebecher). With the help of the battery housing, the electrolyte and other components can also be protected from environmental influences. In order to provide a relatively large capacity with the help of the corresponding battery cell, a plurality of such galvanic cells are usually arranged in a common battery housing, usually up to 100 pieces. In order to make full use of the existing space relatively efficiently and simplify production, the individual components of the galvanic cell are designed to be planar and stacked in an overlapping manner along the stacking direction, so that a substantially square battery stack is formed. In the case of an alternative embodiment, for example, the spacer is designed to be strip-shaped and is respectively equipped with a plurality of electrodes on the opposite sides. The strip is wound into a roll, especially a so-called "winding core".

[0005] The battery housing is shaped according to the arrangement of the galvanic cells used. In this case, it is possible to design the battery housing to be rigid and, for example, to be made of aluminum. In this case, the shape of the battery housing is, for example, square. Such a battery cell is also referred to as a prismatic cell. In an alternative embodiment, the battery housing is created by means of a film surrounding the galvanic cells. Such a battery cell is also referred to as a so-called pouch cell.

[0006] When operating a battery cell, i.e. during charging and also during discharging, it is possible that gases are formed due to undesired chemical reactions. Due to the gases, the pressure in the battery housing increases, so that on the one hand some electrode regions can have poor ion conduction, which leads to performance losses of the battery cell. On the other hand, it is possible that the battery housing is deformed due to the increased pressure, so that in particular the environment of the battery cell is mechanically affected. At relatively high pressures, the battery housing ruptures, so that the electrolyte can escape and the entire battery cell is no longer ready for use. It is also possible that undesired chemical reactions of individual components of the battery cell with the environment occur.

[0007] In order to minimize this gas formation, a specific combination of various materials for the electrodes and electrolyte is required, which on the one hand increases the manufacturing costs. On the other hand, the selection of less reactive electrode materials is often accompanied by a reduction in capacity and / or energy density. As an alternative to this, additional elements are present in the battery housing, for example, by means of which the gases that occur are bound and / or converted. However, due to the additional elements, the weight of the battery cell and the installation space increase, so that the energy density is reduced.

[0008] The object of the present invention is to specify a particularly suitable battery cell in which the operational safety and / or the energy density are advantageously increased.

[0009] This object is achieved according to the invention by the features of claim 1. Advantageous developments and embodiments are the subject matter of the dependent claims.

[0010] The battery cell is designed to be rechargeable and is preferably a secondary battery. Preferably, the battery cell is a component of a motor vehicle in a specified state. The battery cell is suitable for this, in particular, is arranged and established for this. In a specified state, the battery cell is, for example, a component of an energy storage device of a motor vehicle, the energy storage device having a plurality of such battery cells. In this case, the battery cell is preferably divided into a plurality of battery modules, which are structurally identical to each other. The battery cells are arranged in particular in the housing of the energy storage device or the corresponding battery module and are electrically connected in parallel and / or in series with each other. Therefore, the voltage applied to the energy storage device / battery module is a multiple of the voltage provided by each of these battery cells. Here, all battery cells are preferably structurally identical to each other, which simplifies production.

[0011] The housing of the energy storage device or the corresponding battery module (which therefore in particular forms a complex (Verbund) of such a battery cell) is preferably made of metal, for example steel, such as stainless steel, or an aluminum alloy. For example, a die-casting process, a deep-drawing process, a casting process or an extrusion process are used for production. In particular, the housing of the energy storage device or the corresponding battery module is designed to be closed. An interface is suitably introduced into the housing of the energy storage device or the corresponding battery module, which interface forms the connection end of the energy storage device / battery module. The interface is electrically contacted with the battery cell here, so that as long as the corresponding plug is plugged into the connection end, electrical energy can be fed in and / or extracted from the battery cell outside the energy storage device.

[0012] The motor vehicle is preferably land-based and preferably has several wheels, of which at least one, preferably a plurality or all wheels are driven by means of a drive device. In particular, one of the wheels, preferably a plurality of wheels, is designed to be controllable. It is thus possible to move the motor vehicle independently of a specific roadway, such as a track or the like. It is expedient that the motor vehicle can be positioned substantially arbitrarily on a roadway, in particular made of asphalt, tar or concrete. The motor vehicle is, for example, a commercial vehicle, such as a truck (Lkw) or a bus. However, the motor vehicle is particularly preferably a passenger vehicle (Pkw).

[0013] The motor vehicle is suitably propelled by means of a drive device. For example, the drive device, in particular the main drive device, is at least partially designed in an electrical manner, and the motor vehicle is, for example, an electric vehicle. The electric motor is operated, for example, by means of an energy storage device, which is suitably designed as a high-voltage battery. A DC voltage is suitably provided by means of the high-voltage battery, wherein the voltage is, for example, between 200V and 800V and, for example, substantially 400V. Preferably, an electric inverter is arranged between the energy storage device and the electric motor, by means of which the energization of the electric motor is adjusted. In an alternative, the drive device additionally has an internal combustion engine, so that the motor vehicle is designed as a hybrid motor vehicle. In an alternative, the low-voltage power distribution network of the motor vehicle is fed by means of the energy storage device, and in particular a DC voltage of 12V, 24V or 48V is provided by means of the energy storage device.

[0014] In another alternative, the battery cell is a component of a ground transport vehicle, industrial equipment, handheld equipment, such as a tool, especially a cordless screwdriver. In another alternative, the battery cell is a component of an energy supply device and is used there, for example, as a so-called buffer battery. In another alternative, the battery cell is a component of a portable device, such as a portable mobile phone or other wearable device. It is also possible to use such a battery cell in the field of camping, model building or for other outdoor activities.

[0015] The battery cell has a plurality of electrodes, that is, for example, two or preferably more electrodes. In particular, the electrodes are divided into anodes and cathodes, wherein preferably half of the electrodes constitute the anode and the other half constitute the cathode. However, preferably there are more anodes than cathodes. In this case, it is particularly preferred that all anodes and all cathodes are structurally identical to each other, which simplifies manufacturing. For example, the electrode is designed to be planar and in particular has a carrier, which is also referred to as a collector. In particular, the corresponding carrier is formed by means of a metal film, which is coated with a layer at least in sections on one side or on both sides. For example, aluminum is used as the metal of the carrier / collector of the cathode, and copper is used as the metal of the collector of the anode.

[0016] In this case, the layer has a thickness of less than 1 mm. Suitably, the carrier has a thickness of less than 0.1 mm. Preferably, the corresponding layer has an active material, a binder and / or a conductive additive, such as conductive carbon black. The active material is used to absorb / emit working ions, such as lithium ions, and is suitable for this and is arranged and established for this. For example, lithium metal oxides (such as lithium cobalt (III) oxide (LiCoO2)), NMC (such as NMC622 or NMC811), NCA, LNMO or lithium-rich materials are used as active materials for the cathode. Alternatives are, for example, olivine, such as LFP. For example, graphite, Si-based materials or mixtures thereof, lithium metal or LTO are used for the anode.

[0017] In particular, the electrodes are substantially rectangular. For example, the electrodes are stacked overlappingly to form a battery stack, wherein the stacking direction is perpendicular to the extension direction of the electrodes arranged parallel to each other. In this case, the anode and the cathode are preferably alternated in the stacking direction of the battery stack. Suitably, the spacers of the battery stack are respectively arranged between adjacent electrodes, i.e., in particular between one of the anodes and one of the cathodes, respectively, and the spacers are preferably also designed to be planar. For example, all spacers are structurally identical to each other. In particular, the electrodes are stacked substantially flushly and overlappingly, wherein, for example, all anodes at least slightly extend beyond the cathode. Due to the stacking of the electrodes, the battery stack is thus also substantially square.

[0018] In an alternative embodiment, for example, all anodes, all cathodes or separators are formed by means of a common strip or they are fastened to a common strip. The strip itself is wound into a cylindrical shape or the like, so that a so-called "winding core" is formed.

[0019] The battery cell has a battery housing in which electrodes, for example a battery stack or a "jelly roll," are arranged. In particular, the battery housing surrounds the electrode at 0.1 dm 3 and 10dm 3 The volume between. For example, the battery housing is additionally at least partially filled with electrolyte. The battery housing is preferably designed to be rigid. In other words, the battery cell is in particular a prismatic battery. In particular, the battery housing is made of metal, such as aluminum, i.e. pure aluminum or an aluminum alloy. The battery housing has, for example, a square shape. Alternatively, the battery housing is designed to be flexible and, for example, at least partially constituted by means of a metal film, which is in particular coated on one side or on both sides. The electrodes are wrapped by means of the metal film, and the metal film is suitably sealed at the ends, so that electrolyte overflow and / or ambient air entering the battery housing are avoided.

[0020] The electrode is in particular arranged directly in the battery housing, so that the electrode, for example, directly or via another component rests against the inner wall of the battery housing and is therefore stabilized by means of the other component. At least the battery housing is directly used to protect the electrode and / or prevent the electrode / electrolyte from contacting the ambient air or other particles. In other words, the electrode in the battery housing is preferably not, at least not completely, surrounded by means of another component, so that the weight and material costs of the battery cell are reduced. In particular, there is no other housing in the battery housing by means of which the electrode is surrounded. Therefore, it is possible to substantially completely fill the battery housing with the electrode and one / more possible spacers.

[0021] Suitably, the battery housing has at least one or two notches through which the connection terminals are respectively guided. By means of one or more connection terminals, at least some of the electrodes arranged in the battery housing are electrically contacted, depending on the wiring of the electrodes, so that it is possible to feed electrical energy from outside the battery housing into the galvanic cell formed by means of the electrodes or to extract it from the galvanic cell formed by means of the electrodes through the one or more connection terminals. As long as only a single connection terminal is present, at least some of the electrodes are electrically contacted with the battery housing, so that the potential of the battery housing is predetermined by means of these electrodes. In particular, one or more connection terminals are electrically insulated from the battery housing, wherein the connection terminals are connected to the battery housing in a fluid-tight manner, so that electrolyte overflow is avoided in the area of ​​the connection terminals.

[0022] The battery housing has an opening which is designed, for example, to be circular or rectangular. In particular, the area of ​​the opening is between 50 μm 2 Up to 15mm 2 between, preferably between 0.2 mm 2 Up to 3mm 2 The opening is covered by means of a gas-permeable diaphragm. In particular, the diaphragm is rigidly connected to the battery housing so that a movement of the diaphragm relative to the battery housing is avoided. The diaphragm has a larger area than the opening so that the diaphragm completely overlaps the opening. In particular, the area of ​​the diaphragm is smaller than the area of ​​a possible side of the battery housing having the opening. In this way, material costs are reduced.

[0023] Preferably, the diaphragm is connected to the battery housing in a liquid-tight and / or gas-tight manner, so that liquid and / or gas entering the opening through the membrane and the battery housing is avoided. Particularly preferably, in this case the diaphragm is welded to the battery housing, appropriately using a circumferential weld. As an alternative to this, for example, the diaphragm is connected to the battery housing in a form-fitting and / or material-fitting manner, in particular adhesively bonded. In this case, the opening is suitably completely surrounded by means of an adhesive or a weld. For example, the connection is made directly adjacent to the opening, or a distance is formed between the opening and the connection of the diaphragm to the battery housing, such as an adhesive or a weld. Therefore, it is possible for gas to escape from the battery housing or enter the battery housing only through the opening, wherein the gas is also guided through the diaphragm.

[0024] In particular, the diaphragm is selected so that it is permeable to preferably at least CO, CO2, H2 and / or CH4. For example, the passage of such gases is not hindered or is only hindered to a relatively small extent by means of the diaphragm. However, the permeability of the diaphragm to moisture, in particular water vapor, is low. In particular, the diaphragm has a ratio of CO2 permeability to moisture permeability of at least 0.5 or at least 1 or at least 1.5. This ratio is preferably greater than 0.5 and less than 3. In summary, the diaphragm is designed so that the gas formed in the battery housing can pass through the diaphragm out of the battery housing through the opening, for which the opening is used. Here, the entry of moisture, in particular water vapor, into the battery housing is made difficult by means of the diaphragm.

[0025] The diaphragm itself is covered with a covering element on the outside, that is, offset outward relative to the battery housing. By means of the covering element, at least the part by which the covering opening of the diaphragm is covered in this case. In particular, the opening is covered by means of the covering element. In this case, it is possible that the covering element is also arranged in the battery housing, but offset in the direction of the opening relative to the diaphragm. Alternatively, the covering element is located outside the battery housing. For example, the covering element is against the battery housing and / or the diaphragm or is spaced apart from one or both of them. In particular, the covering element is at least partially rigid. The covering element is used to limit the entry of materials, especially moisture, especially water vapor into the battery housing, and is suitable for this, especially provided and established for this. Here, the entry of materials into the diaphragm is also preferably limited by means of a covering element. In other words, by means of the covering element, it is especially set: how much and / or whether a substance such as a liquid or preferably a gas enters the battery housing through the diaphragm and through the opening. In other words again, the opening is preferably closed at least temporarily by means of a covering element. At least the cover element is preferably designed such that the passage of gas through the membrane and the opening is limited or at least temporarily limited by means of the cover element and thus set. The cover element is preferably fluid-tight, for example always or at least when the cover element is in a specific state, for example a closed state. In other words, in this state, preferably due to the principle and / or construction, further conducting liquids, in particular water, are excluded as much as possible. If or as long as no gas is formed in the battery housing, the cover element is preferably in a specific state.

[0026] Due to the opening and the diaphragm, the escape of the gas formed in the battery housing is possible, so that the formation of excessive pressure in the battery housing is avoided, which may cause damage to the electrodes and / or the battery housing. Thereby improving operational safety. For this purpose, only a diaphragm and a cover element are required, for which only a relatively small space volume is required. In addition, it is possible to arrange the cover element outside the battery housing so that the energy density is not negatively affected. Due to the cover element, the diaphragm is at least partially protected from environmental influences outside the battery housing, so that damage to the diaphragm is avoided. Especially in a specific state when the gas entry and / or gas escape are completely prevented by means of the cover element, for example, particles from the environment are at least temporarily / partially away from the diaphragm by means of the cover element. Thus, the diaphragm is not loaded with liquid, especially water vapor, from outside the battery housing, so that despite the continued existence of the diaphragm to the liquid, even if the permeability is reduced, the liquid invasion is still completely prevented. Conversely, if gas can temporarily escape from the battery housing by means of the cover element, water can also penetrate the membrane during this period, but this is a relatively small amount that is substantially completely prevented by means of the membrane. Thus, water penetration into the battery housing is almost completely prevented.

[0027] The diaphragm is in particular made of a polymer and is for example a film, for example a polymer film. The diaphragm is suitably made of or consists of PTFE, ie polytetrafluoroethylene. The diaphragm expediently has a crystallinity between 85% and 100% and a viscosity of 0.2 g / cm 3 Up to 2g / cm 3 In the case of this material selection, gas permeability is given, wherein the penetration of moisture, especially water vapor, into the battery housing is prevented or at least made more difficult by means of the diaphragm. In particular, the diaphragm described in WO 2021 / 079163 A1 is used as the diaphragm.

[0028] For example, the opening is positioned arbitrarily at the battery housing. However, if the battery cell is designed as a pouch cell, the opening is particularly preferably located in the region of one of the ends of the cylindrical shape close to the collector, in which region in particular a possible film seal (for example on a so-called air bag) is located. In this case, the opening is expediently offset inwards from the respective end by at most one third of the maximum length of the battery housing.

[0029] If the battery cell is a prismatic battery, the opening is preferably located in the region of the end faces and / or narrow faces, which in particular are not parallel to the electrodes layered into a possible battery stack. As an alternative to this, the opening is located in a side of the battery housing that is parallel to the electrodes, but preferably in the edge region, i.e. offset inwardly from the edge by up to one third of the width of the side. Due to this position of the opening, the construction is simplified and there is no need to modify existing design drafts of the battery stack. In addition, the opening is thus arranged in the region of the formed gas accumulation, so that a relatively efficient transport of the gas through the opening can be achieved.

[0030] For example, the diaphragm is fastened to the outside of the battery housing. In this way, the internal space of the battery housing is not filled with the help of the diaphragm, so that a relatively large volume can be used for electrodes there. Thereby further ensuring the high capacity of the battery cell. However, the diaphragm is particularly preferably fastened to the inner wall of the battery housing. In this way, even if the pressure in the battery housing is relatively high, if the design of the diaphragm does not allow the gas to pass immediately, the diaphragm does not protrude excessively outward. Therefore, the diaphragm is stabilized by means of the inner wall, which increases robustness. In the case of overpressure, the diaphragm is also pressed against the inner wall, and thus prevents gas from passing between the battery housing and the diaphragm. Therefore, it is possible for gas to escape only through the diaphragm, which is thus carried out in a controlled manner. In summary, in particular, the diaphragm is arranged on the side of the battery housing that points outward or inward.

[0031] For example, the cover element is operated as a function of the temperature. In this case, the cover element is expediently designed such that at temperatures below a limit value, the ingress and / or egress of gas is completely prevented, so that the membrane is not loaded with fluid from outside the battery housing by means of the cover element. If, however, the temperature of the battery cell is greater than the limit value, the cover element is in particular designed such that the escape of gas from the battery cell is not prevented by means of the cover element. In other words, the membrane is released. However, it is therefore possible that moisture, in particular water vapor, reaches the membrane from outside the battery housing.

[0032] In this case, the limit value is expediently between 25° C. and 60° C. Due to this limit value, the cover element is in particular only dimensioned such that gas escape is possible when the battery cell is in operation, i.e. when electrical energy is fed into the battery cell and / or is extracted from the battery cell. Only in this time period is it possible for gas to form, which can escape. Conversely, when the battery cell is not required, the diaphragm is protected by means of the cover element.

[0033] Alternatively or in combination therewith, the cover element is actuated as a function of the pressure difference between the pressure outside the battery housing and the pressure in the space formed between the cover element and the diaphragm. In particular, the volume of the space is less than 4 cm 3 , 1cm 3 or 0.5cm3 The pressure in the space between the cover element and the diaphragm is, in particular, equal to the pressure in the battery housing or is slightly reduced by the diaphragm.

[0034] The cover element is especially operated so that if the pressure in the space is greater than the pressure outside the battery housing, for example, greater than 0.1 bar, 0.5 bar, 1 bar, 2 bar or 5 bar than the pressure outside the battery housing, the gas escapes from the battery housing is possible or at least simplified. Otherwise, the cover element is especially closed so that the gas escape is completely prevented. Here, the diaphragm is also protected from the influence of liquid from outside the battery housing by means of the cover element. Therefore, only when the pressure on the side of the cover element facing the inside of the battery housing increases compared with the pressure outside the battery housing, the protection of the diaphragm by means of the cover element is reduced. However, in this case, the flow direction of the gas points to the outside of the battery housing. Due to the flow direction of the gas, liquid intrusion is prevented until the diaphragm. If the pressure difference drops, the speed of the gas is also reduced, so that moisture, especially water vapor intrusion will be possible. However, the cover element is then closed again, which also prevents liquid intrusion.

[0035] For example, the covering element is a porous element or includes a porous element, wherein the pores are particularly open. For example, the porous element is a foam ceramic. By means of the porous element, the path length that the incoming gas must pass through is increased, so that an increased resistance is provided for the escaping gas. Therefore, the escape of gas from the battery housing is limited by means of the porous element. Due to the porous element, the intrusion of moisture, especially water vapor, is prevented or at least made difficult, especially due to the capillary effect. For example, the porous element is designed to be completely liquid and / or gas impermeable at least in a specific area, for example, at one side, so that the path to be passed for gas and liquid and therefore the fluid technology resistance are further increased. In particular, the side of the porous element opposite to the opening is designed so that the path to be passed for gas / liquid through the porous element is relatively long. In particular, the porous element is substantially square, which simplifies production.

[0036] The covering element particularly preferably comprises a valve or is constituted thereby. The valve is operated, for example, by means of an actuator, for example a piezoelectric actuator. It is therefore possible, in particular according to certain conditions, such as a possible pressure difference, to control the escape of gas from the battery housing. Preferably, the covering element has a sensor, according to which the actuator is controlled. Alternatively, the valve is, for example, spring-loaded and is in particular designed as a non-return valve. In particular, the valve is operated according to the pressure difference between the pressure existing outside the battery housing and the pressure in the space formed between the covering element and the diaphragm, i.e. when the pressure must exceed a certain limit value. In this case, it is possible to adapt to different fields of use and / or other presets by replacing the spring.

[0037] For example, the valve is a body that is impermeable to gases and liquids, which is, for example, diaphragm-shaped. For example, when the covering element / valve is in the closed state, the opening or the diaphragm is completely covered by the body. By means of a longitudinal displacement, in particular perpendicular to the extension direction of the body and / or the diaphragm, the covering element is transformed into an open state, and the body is preferably placed accordingly. Due to the longitudinal displaceability, even in the open state of the covering element, direct intrusion of liquid into the opening is prevented. Alternatively, the covering element is designed according to the type of a flap (Klappe), and is therefore placed in particular in a swingable manner relative to the battery housing and / or at the battery housing. For example, in this case, the possible body of the body is placed at the battery housing by means of a bearing (Lager) or a particularly preferably thin film movable joint (Filmscharnier). The construction is simplified in this way.

[0038] In an alternative to this, the covering element has a plastic, preferably polymer layer, which is applied, for example, directly to another body, for example a film. In this case, the polymer layer comprises a microstructure or nanostructure, that is, a structure with an extension between 100 μm and 1 nm. In particular, the structure is repeated periodically, so that a pattern is formed. In this way, production is simplified. The structure is, for example, a flap and / or a grass-like object. As far as grass-like structures are concerned, these are especially directed away from the interior of the battery housing, so that in the event of an increase in pressure outside the battery housing or in the event of liquid reaching the battery housing, the grass-like structures are pressed flat against the bottom of the polymer layer, so that the covering element is designed to be relatively tight. Alternatively or in combination therewith, the structure can be set, for example by applying a voltage, so that the passage of gases and liquids is enabled or prevented. Due to the microstructure or nanostructure, the mechanical robustness is increased and the space requirement is reduced.

[0039] In another alternative, the covering element has a plurality of cover wings, i.e., for example, two cover wings, three cover wings, four cover wings, five cover wings or more cover wings. Preferably, the number of cover wings is less than ten, so that the construction is simplified. The cover wings are connected to the battery housing, for example, they are fastened directly thereto or indirectly thereto via another element. In this case, the cover wings are connected to the battery housing at different points, i.e., at corresponding connection points, i.e., spaced apart from each other. In particular, the connection points surround the opening. Suitably, the cover wings are connected only on one side. The cover wings at least partially overlap with the diaphragm, i.e., in particular, also overlap with the opening, or at least overlap with a portion of the diaphragm by means of which the opening is covered. In addition, the cover wings cover each other. In other words, one of the cover wings at least partially covers one or more of the remaining cover wings.

[0040] The cover wings are designed to be flexible, i.e. elastically deformable. In particular, the cover wings are designed from a material that is impermeable to gases and liquids. Due to the flexible design of the cover wings, it is possible to bend them so that the diaphragm is released. In this case, the cover wings are mutually stabilized so that, on the one hand, an unintentional bending of one of the cover wings does not lead to the release of the diaphragm. The forces required for this are also relatively high. Due to the mutual overlap, there are also relatively large creepage distances, so that it is basically impossible for liquid to penetrate into the diaphragm between the cover wings and it is basically impossible for gas to escape here in the opposite direction to the cover wings that are in contact with the battery housing. However, by bending all or at least some of the cover wings upwards, it is possible to release the diaphragm and thus enable gas to escape.

[0041] Particularly preferably, the cover wing is connected to the outside of the battery housing so that pressing in of the cover wing, which could lead to damage to the diaphragm, is avoided. For example, the cover wing is designed so that in the event of an increase in pressure on the side of the diaphragm, it is bent so that gas can escape. As an alternative to this, the cover wing is made of two different materials, for example, which shrink differently when the temperature increases. Therefore, at increased temperatures, the cover wing is bent and the membrane and therefore the opening are also released.

[0042] Particularly preferably, the battery cell comprises a drying element for reducing the penetration of moisture into the battery housing through the opening. The drying element is suitable for this purpose, in particular is provided and designed for this purpose. Due to the drying element, moisture, such as, for example, water in a liquid or gaseous state, which penetrates despite the covering element, is thus bound, so that undesired reactions with electrodes arranged in the housing and / or any electrolyte are prevented. This further increases the operational safety. In particular, the drying element is designed such that the binding of water, in particular the absorption of water molecules, is achieved by means of the drying element.

[0043] For example, the drying element is arranged in the region of the opening and, for example, surrounds the opening. In particular, the drying element has a plurality of silicon-containing groups connected to the diaphragm. In other words, the diaphragm is functionalized with silicon-containing groups. Thus, the space requirement is reduced. Particularly preferably, the drying element is diaphragm-shaped and, for example, is loosely placed on the diaphragm or is spaced from the diaphragm. Due to the arrangement on the inner side of the diaphragm, only the part of the liquid, in particular water, that enters the interior of the battery housing through the diaphragm is blocked by means of the drying element. In other words, the diaphragm is first used to block moisture / liquid, and only then the drying element is used. This also enables the battery cell to be operated for a relatively long time without the functional mode of the drying element being abolished.

[0044] For example, the diaphragm is designed to be tear-resistant. However, the diaphragm is particularly preferably designed so that it tears when the pressure difference between the pressure outside the battery housing and the pressure inside the battery housing exceeds a limit value. In this way, damage to the battery housing is avoided. For example, the diaphragm tears completely and thus breaks. Expediently, the tearing only occurs when the limit value is exceeded. If the pressure difference falls below the limit value again, the tearing is in particular terminated. In this way, complete destruction of the diaphragm can be prevented.

[0045] For example, the battery cell has a plurality of openings, each of which is covered by means of a corresponding gas-permeable diaphragm, wherein each diaphragm is covered on the outside with an assigned covering element in order to limit the entry of moisture into the battery housing. For example, a plurality of or all of the openings are covered with the same covering element. In particular, in this case all openings / diaphragms / covering elements are structurally identical to one another and differ only in their position at the battery housing. Alternatively, for example, the covering element and / or the diaphragm are designed in different ways so that they are permeable in different ways and / or operated under different pressure differences or other conditions. Thereby increasing flexibility.

[0046] However, it is particularly preferred that the battery cell has only a single opening, which simplifies production. In particular, the diaphragm rests against the stabilizing element at least in the region of the opening and is fastened to the stabilizing element, for example. In other words, the stabilizing element at least partially covers the opening. The stabilizing element is preferably designed to be rigid and, for example, is made of metal. Preferably, the stabilizing element is appropriately fastened to the battery housing by means of welding. The stabilizing element has other openings, which are respectively covered by the opening. Therefore, the effective area available for the escape of gas from the battery housing is limited to the sum of the other openings, so that relatively large openings can also be selected without excessive gas escaping from the battery housing or liquid entering the battery housing.

[0047] Suitably, the stabilizing element is offset outwards compared to the diaphragm. Therefore, the maximum deformation of the diaphragm is predetermined by means of other openings and the diaphragm is thus stabilized. For example, the stabilizing element is designed so that the stabilizing element ruptures when the pressure difference between the pressure inside the housing and the pressure outside the battery housing increases. For this purpose, the stabilizing element has, for example, one or more rated breaking points, which are manufactured, for example, by means of laser or embossing. The pressure difference at which this aspect occurs can be set relatively accurately in this case. Alternatively or in combination with this, the stabilizing element is designed so that the stabilizing element ruptures when a specific temperature is exceeded. Due to the rupture, the diaphragm is no longer stabilized and is therefore also overloaded, so that the diaphragm is torn. Therefore, a relatively large volume of gas is possible through the opening. In particular, the covering element is also broken in this case or at least is set so that the gas escape is basically possible without obstruction. Thereby, the battery cell is deflated in a controlled manner and uncontrolled damage to the battery housing due to excessive pressure is avoided. Although the battery cell is damaged in this way and can no longer be used, the load on the environment is reduced. In other words, the diaphragm and the stabilizing element act in the manner of a rupture disk.

[0048] Alternatively to the previously described embodiment or in combination with the previously described embodiment, the battery housing appropriately has an integrated rated breaking point. The integrated rated breaking point is, for example, spatially separated from the opening, or, for example, the integrated rated breaking point has an opening. In another alternative, the rated breaking point is constituted by an opening. For example, the rated breaking point is a surface of the battery housing with a reduced wall thickness. Alternatively or in combination, the rated breaking point is, for example, a surface of the battery housing with a concave plate (Gravur) and / or a groove. In an improved embodiment, the rated breaking point is an additional opening in the battery housing that is closed with a rupture disk. In other words, the battery housing has an additional opening that is completely closed by means of a rupture disk. Suitably, the rated breaking point has a size between 0.01% and 50% of the area of ​​the battery housing. The rated breaking point preferably has a size between 0.1% and 40% of the area of ​​the entire battery housing and in particular between 0.3% and 30%. For example, the diaphragm has an area that is 50% larger than the opening.

[0049] For example, the diaphragm is arranged at the inwardly directed side of the battery housing. For example, here, the diaphragm outside the opening is not in complete physical contact with the battery housing. In an alternative, the diaphragm is partially spaced apart from the battery housing in a planar manner via a spacer.

[0050] In another alternative, the battery housing comprises, for example, an auxiliary opening closed with a rupture disk having an opening covered with a gas-permeable diaphragm. For example, the rupture disk is formed by reducing the wall thickness of the battery housing or is a component that is first separated from the battery housing and is fastened to the battery housing for installation. In particular, the possible rated breaking point is formed by means of the rupture disk. The diaphragm is preferably fastened to the outwardly pointing side of the rupture disk. Here, for example, on the outside, the diaphragm rests against another or possible stabilizing element, which has a plurality of additional openings. The stabilizing element is preferably fastened to the rupture disk in this case. In an alternative, the diaphragm is arranged on the inwardly pointing side of the rupture disk, wherein the diaphragm is partially supported in a planar manner on the rupture disk via a spacer.

[0051] The invention further relates to a combination of such a battery cell, wherein the combination is preferably a battery module or a high-voltage battery. The invention further relates to a motor vehicle, such as a passenger car (PKW), having such a battery cell, in particular such a combination. The battery cell is used in particular to energize a main drive of the motor vehicle.

[0052] The advantages and developments described in conjunction with the battery cell can also be transferred to the complex / motor vehicle and to one another and vice versa.

[0053] Embodiments of the present invention are explained in more detail below with reference to the accompanying drawings, in which:

[0054] Figure 1 A motor vehicle having a plurality of structurally identical battery cells is shown schematically in a simplified manner,

[0055] Figure 2 One of the battery cells with a battery housing is shown schematically in a sectional view,

[0056] Figure 3-6 A battery housing is schematically shown in sections at different pressures within the battery housing, the battery housing having an opening for the escape of gas, wherein the opening is covered with a gas-permeable membrane, and wherein the membrane is covered on the outside with a covering element in order to limit the escape of gas from the battery housing,

[0057] Figure 7 , Figure 8 An alternative embodiment of a battery cell is schematically shown in each case.

[0058] Fig. 9 , Fig.10 An alternative embodiment of a stabilization element is shown in each case in a top view.

[0059] Figure 11-13 An alternative embodiment of a battery cell is schematically shown in each case, and

[0060] Figure 14-17 Alternative embodiments of the cover element are respectively shown schematically.

[0061] In all the Figures, parts that correspond to one another are provided with the same reference symbols.

[0062] exist Figure 1 2 shows a motor vehicle 2 in the form of a passenger car (Pkw) in a schematically simplified manner. The motor vehicle 2 has a plurality of wheels 4, at least some of which are driven by means of a drive device 6 comprising an electric motor. The motor vehicle 2 is therefore an electric vehicle or a hybrid vehicle. The drive device 6 has an inverter, by means of which the electric motor is fed. The inverter of the drive device 6 is in turn energized by means of an energy storage device 8 in the form of a high-voltage battery. For this purpose, the drive device 6 is connected to an interface 10 of the energy storage device 8, which interface 10 is introduced into an energy storage device housing 12 of the energy storage device 8, which is made of stainless steel.

[0063] A plurality of battery modules of identical structure to each other, not shown in more detail, are arranged in the energy storage housing 12 of the energy storage 8, and each of the battery modules includes a plurality of battery cells 14. The battery cells 14 of each battery module are partially electrically connected in series with each other and partially electrically connected in parallel with each other. The battery modules are again electrically connected in series and / or in parallel with each other. The electrical connection (Verband) of the battery module is electrically contacted with the interface 10, so that when the drive device 6 is operated, the battery module and thus also the battery cell 14 are discharged or charged (regenerated). Due to the electrical connection, the voltage of 400V or 800V provided at the interface 10 is a multiple of the voltage provided by each of the battery modules and also by each of the battery cells 14.

[0064] exist Figure 2 In the figure, one of the battery cells 14 with the same structure is shown in a cross-sectional view. The battery cell 14 has a plurality of anodes 16 and cathodes 18, of which only two are shown respectively. The anodes 16 and cathodes 18 constituting the electrodes 20 of the battery cell 14 are respectively designed to be planar and alternately stacked in the battery stack, wherein the spacers not shown in more detail are arranged between the respectively adjacent anodes 16 and cathodes 18. The anode 16 protrudes beyond the cathode 18 on the common side, i.e., the respectively corresponding collector, which is formed by means of the corresponding metal film. In the area of ​​the protrusion, the corresponding collector has no other components, but in other areas, a layer is applied on the corresponding collector, which is also called a carrier, and the layer includes an active material. The cathode 18 also protrudes beyond the anode 16 in the same way, wherein the protrusion is located on the opposite side of the stack formed by means of the anode 16 and the cathode 18.

[0065] The protruding parts of the anode 16 and the cathode 18 are respectively welded to a busbar 22 (tab) made of copper. In this case, a common busbar 22 is assigned to the anode 16 and the cathode 18. The busbars 22 each have a connection end 24, which is guided through a battery housing 26 in which the anode 16 and the cathode 18 are arranged. In other words, the electrodes 20 are arranged in the battery housing 26. The battery housing 26 is designed to be rigid and is made of aluminum, i.e., a material containing aluminum. Therefore, the battery cell 14 is a prismatic battery. The battery housing 26 is filled with a liquid electrolyte that is not shown in more detail.

[0066] exist Figure 3-6 , a battery cell 14 is schematically shown in section during operation. The battery housing 26 has an opening 28 with a width of 50 mm. 2 In this case, the opening 28 is located in the same wall of the battery housing 26 in which the recess for one of the connection terminals 24 is also introduced. Apart from the opening 28, the battery housing 26 is designed to be fluid-tight and gas-tight. Thus, the area between the connection terminal 24 and the recess of the battery housing 26 assigned thereto is filled with a plastic that is not shown in greater detail.

[0067] The opening 28 is covered with a gas-permeable membrane 30, which is fastened to the inner wall 32 of the battery housing 26 with the opening 28, that is, fastened by welding or bonding. In the case of the example shown, the membrane 30 covers the entire inner wall 32 of the housing 26 and therefore also completely covers the opening 28. The membrane 30 is at least partially composed of PTFE. Therefore, it is relatively easy for gases such as H2, CO, CH4 and CO2 to escape through the membrane 30, while the passage of moisture, especially water vapor and other liquids is difficult in comparison. The membrane 30, that is, the part by which the opening 28 is covered, is covered with a covering element 34 on the outside relative to the battery housing 26. The covering element 34 is located at the outside of the battery housing 26 and is fastened to the battery housing. The covering element 34 is airtight and liquid-tight and is used to limit the entry of gases into the battery housing 26. The covering element 34 therefore completely prevents moisture, in particular water vapor, from the surroundings from penetrating into the opening 28 and thus also into the membrane 30 .

[0068] When operating the battery cell 14, it is possible that due to undesirable chemical reactions, for example due to a relatively high load or due to undesirable foreign particles, gases 36, such as H2, CO, CH4 and / or CO2, are formed in the battery housing 26. In this case, the gas 36 requires a larger volume than the reactants, so that the pressure in the battery housing 26 increases. Figure 4As shown in FIG, it is possible for gas 36 to enter through the membrane 30 into the opening 28 , ie into the space 38 formed between the cover element 34 and the membrane 30 , which space is defined in this embodiment by means of the opening 28 .

[0069] If the pressure difference between the pressure outside the battery housing 26 and the pressure in the space 38 exceeds a limit value, such as 0.5 bar, the cover element 34 is operated so that it is partially opened. As a result, gas escapes from the space 38 into the environment of the battery housing 26, such as in Figure 5 . Gas 36 also continues to flow from the interior of the battery housing 26 through the membrane 30 and the opening 28 into the environment. In this case, moisture is prevented from entering the battery housing 26 by means of the membrane 30 (see also below).

[0070] If the pressure difference between the pressure in the space 38 and the pressure outside the battery housing 26 decreases again due to the at least partial escape of the gas 36, the cover element 34 is closed again so that a further escape of the gas 36 from the space 38 and thus from the battery housing 26 no longer occurs, as in Figure 6 The membrane 30 is therefore then completely covered again by means of the covering element 34 , so that the penetration of moisture into the opening 28 is prevented.

[0071] Due to the construction of the battery cell 14, the entry of moisture from outside the battery cell 26 to the electrode 20 will only be possible when the cover element 34 is operated so that the passage of gas is possible. In this case, however, the gas 36 flows from the interior of the battery housing 26 to the outside, so that the intrusion of moisture is eliminated or at least greatly reduced due to the flow movement of the gas 36.

[0072] In an alternative embodiment, the cover element 34 is additionally or alternatively actuated solely as a function of the temperature of the battery cell 14. In this case, the cover element 34 is actuated such that when the temperature of the battery cell 14 exceeds a limit value, such as 40°C, an escape of the gas 36 is possible.

[0073] Furthermore, the diaphragm 30 is designed such that if the pressure difference between the pressure outside the battery housing 26 and the pressure inside the battery housing 26 exceeds a (further higher) limit value, the diaphragm tears. This limit value, i.e. the further limit value, is 10% to 25% lower than the maximum pressure load of the battery housing 26, i.e. the pressure difference at which irreversible destruction of the battery housing 26 occurs. The maximum pressure load is in particular between 6 bar and 8 bar. In other words, the diaphragm 30 acts as a rupture diaphragm, which tears to avoid destruction of the battery housing 26.

[0074] Thus, if a relatively large volume of gas 36 is formed, it enters the space 28, so that the cover element 34 is actuated. The pressure in the space 28 thus corresponds substantially to the pressure in the environment of the battery housing 26, i.e., outside the battery housing 26. If the pressure difference between the pressure in the space 28 and the pressure in the interior of the battery housing 26 then exceeds a further limit value, the diaphragm 30 tears in a controlled manner, so that the escape of the gas 36 from the interior of the battery housing 26 into the environment is accelerated due to the lack or reduced fluidic resistance of the diaphragm 30. Damage to the housing 26 due to excessive pressure in the interior of the battery housing 26 is thus avoided.

[0075] If the pressure difference drops below another limit value again, the tearing of the diaphragm 30 stops. Even if most of the gas 36 escapes, so that the pressure difference between the environment of the battery housing 26 and the pressure in the space 28 is below the limit value of 0.5 bar, the cover element 34 is actuated again so that the opening 28 is completely covered by means of the cover element. Thus, the penetration of moisture into the battery housing 26 is again avoided by means of the cover element 34. Therefore, the continued operation of the battery cell 14 is also possible, wherein however, due to the torn diaphragm 30, the penetration of liquid is at least temporarily and partially achieved.

[0076] exist Figure 7 It is shown in Figure 3 . In this variant, the battery cell 14 has a drying element 40. The drying element 40 is composed of silicon-containing groups and exists as a layer, with the help of which the diaphragm 30 is coated flatly on the inside, that is, in this variant, over the entire surface and is thus covered. In other words, the drying element 40 exists as a layer separated from the diaphragm 30. With the help of the drying element 40, the passage of the gas 36 is not hindered or only slightly hindered. However, with the help of the drying element 40, the moisture, that is, water (steam), that still reaches through the opening 28 and the diaphragm 30 is bound and / or absorbed so that it cannot reach the electrode 30 and / or the electrolyte. Therefore, the drying element 40 is used to reduce the moisture that penetrates into the battery housing 26 through the opening 28.

[0077] exist Figure 8 It is shown in Figure 3 Another modification of the illustrated battery cell 14 is shown. In this variant, the opening 28 is covered on the outside by means of a diaphragm 30, and the diaphragm 30 is fastened to the outside of the battery housing 26, i.e. fastened by means of welding or bonding. In addition, the battery cell 14 has a stabilizing element 42 made of metal. The stabilizing element 42 is designed to be planar and rests against the diaphragm 30 over the entire surface. Therefore, the diaphragm 30 also rests against the stabilizing element 42 in the area of ​​the opening 28. The diaphragm 30 is arranged here between the battery housing 26 and the stabilizing element 42, which is therefore offset outward relative to the diaphragm 30.

[0078] exist Fig. 9 and 10 In each of the figures, an embodiment of a stabilization element 42 is shown in a top view. They each have a plurality of further openings 44. Fig. 9 In the variant shown in , the other openings 44 are each separated from one another and provided by means of circular recesses. Fig.10 In the variant shown in FIG. 4 , the further openings 44 are strip-shaped.

[0079] The further openings 44 or at least a part of them are arranged above the openings 28 and thus cover the further openings with the openings 28. The stabilizing element 42 and thus also the diaphragm 30 are covered over the entire surface with the cover element 34, which is also arranged outside the battery housing 26. In the case of increased pressure in the battery housing 26 and in the case of at least partial opening of the cover element 34, the diaphragm 30 only slightly bulges outward in the region of the further openings 44, so that excessive deformation of the diaphragm 30 is avoided. Only when the pressure difference between the interior of the battery housing 26 and the environment of the battery housing 26 exceeds another limit value, namely 6 bar to 8 bar, does the stabilizing element 42 break, so that the diaphragm 30 is no longer stabilized with the help of the stabilizing element. The diaphragm is thus torn, so that a relatively large volume of gas 36 can escape unhindered.

[0080] exist Fig.11 , a variant of the cover element 34 is shown in a top view. The cover element 34 has a plurality of cover wings 46, which are connected at connection points 48 spaced apart from each other, i.e. fastened to the battery housing 26. The connection points 48 surround the opening 28, and the cover wings 46 are arranged so that they at least partially cover each other and the opening 28 at the ends opposite the respective connection points 48 and thus also cover the diaphragm 30. The cover wings 46 are designed to be flexible and are made of a polymer, for example. When the pressure difference exceeds a limit value, the cover wings 46 are lifted from the battery housing 26 at the free ends spaced apart from the respective connection points 48 due to the increased pressure, so that gas can escape, otherwise the cover wings 46 are flat against the battery housing 26. If the pressure difference is lower, however, gas is prevented from escaping from the battery housing 26 and / or moisture from the outside of the battery housing 26 from entering the opening 28 or at least the diaphragm 30 due to the relatively large creepage distance, which is provided by means of the overlap. In an alternative embodiment, the cover wing 46 is made of two different materials with different temperature characteristics. Here, the material of the part of the cover wing 46 facing the outside of the battery housing 26 is selected so that when the temperature rises, the material shrinks more. Therefore, at an increased temperature, the cover wing 46 deforms, so that the opening 28 and thus the diaphragm 30 are exposed.

[0081] exist Fig.12 , a cell 14 is again schematically shown in a simplified manner in sections in a sectional view. In this variant, the opening 28 is again covered on the outside by means of a diaphragm 30. The diaphragm 30 is again completely covered by means of a cover element 34, which comprises a porous element 50, i.e. a foam ceramic or a foam material. The porous element 50 has a plurality of open pores, which are not shown in greater detail. Gas can pass through due to these pores, wherein the gas passage is restricted due to the increased fluid resistance.

[0082] On the side opposite to the membrane 30, the square porous element 50 is provided with a layer 52, which is designed to be completely fluid-tight. By means of the layer 52, it is ensured that the escaping gas 36 takes a relatively long path to escape through the porous element 50, wherein the structural size of the cover element 34 is not excessively increased. By means of the layer 52, it is also ensured that the escaping water also reaches the opening 28 only after a relatively long path through the porous element 50, which is delayed relatively long due to the capillary effect.

[0083] exist Fig.13 In, according to Fig.12 Another design of a battery cell 14 is shown. Here, the diaphragm 30 is also arranged on the outside of the battery housing 26 and covers the opening 28. The cover element 34 is also arranged on the outside of the housing 26. The cover element 34 includes a valve 54 and is formed by the valve in the embodiment shown. The valve 54 has a fluid-impermeable body 56, which is shaped so that when the body 5 is against the battery housing 26 at the edge side, the entire diaphragm 30 is closed by means of the body. The body 56 is made of plastic and is placed in a longitudinally displaceable manner perpendicular to the surface of the diaphragm 30 by means of a guide device not shown in more detail. In addition, the body is supported at the stop 58 by means of a plurality of springs 60, wherein the body 56 is located between the stop 58 and the diaphragm 30. The spring 60 is designed so that as long as the pressure difference between the pressure in the housing 26 and the environment of the battery housing 26 is less than a limit value of 0.5 bar, the body 56 is pressed against the diaphragm 30 and the battery housing 26 by means of the spring. If the limit value is exceeded, the body 56 is spaced apart from the diaphragm 30 due to the pressure, counter to the force applied by means of the spring 60 , so that the gas 36 can escape.

[0084] In a variant not shown in greater detail, the spring 60 is replaced by an actuator or an actuator is additionally present. When certain conditions, such as a certain temperature increase, exist, the actuator, such as a piezoelectric actuator or a magnetic element, is actuated to space the body 56 from the diaphragm 30 .

[0085] exist Fig.14, an alternative embodiment of the valve 54 is shown. In this embodiment, the body 56 is pivotably mounted on another component of the cover element 34 or the battery housing 26 by means of a movable joint 62, such as a film movable joint. In a variant, the valve 54 is designed as a non-return valve, so that liquid reaching the body 56 from the outside causes the valve 54 to close. In a variant that is not shown in more detail, the body 56 is also loaded by means of a spring 60 that is not shown in more detail, and if the pressure difference is less than a limit value, the body 56 is pressed or pulled into a closed position by means of the spring 60. In another variant that is not shown, the body 56 is additionally or alternatively actuated by means of an actuator.

[0086] exist Fig.15 and 16 A modified form of the covering element 34 is shown in . In an alternative, the polymer layer 64 is applied to a component separate therefrom, or a further diaphragm is formed by means of the polymer layer 64. The polymer layer 64 has a bottom 66, to which a plurality of nanostructures 68 are fastened. The nanostructures 68 are each spaced 200 nm apart from one another and are arranged in a repeating pattern. Each nanostructure 68 has a pin 70 fastened to the bottom 66 and pointing away from it, to which a thickening 72 is connected at a free end opposite to the bottom 66. The extension of the thickening 72 depends on the applied voltage. In the normal state of the covering element 34, i.e. when no voltage is applied, the thickening 20 expands so that respectively adjacent thickenings 20 are in contact with one another, so that passage of gas 36 is impossible, as in Fig.15 If a voltage is applied, the thickened portion 72 contracts, so that adjacent thickened portions 20 are spaced apart from each other. Therefore, the gas 36 can pass through, as shown in Fig.16 as shown in .

[0087] exist Fig.17 , a modification of the cover element 34 is shown, which is also formed by means of a polymer layer 64. However, in this modification, the nanostructure 68 is designed as micrograss. In other words, each bolt 70 only stands alone from the bottom 66 and the bolt is designed to be relatively flexible. In this case, as in the previous embodiment, the bolt 70 is away from the battery housing 26 or points outward. In the case of droplets arriving from the outside, the bolt 70 is bent to the bottom 66 so that the bolts 70 are stacked and abut against each other. Therefore, moisture is avoided from passing. Once the moisture is removed, the bolt 70 basically takes the original position again. In the case of a bolt 70 oriented in a straight line, it is always possible for the gas 36 to pass from the opposite direction.

[0088] In a variant not shown in more detail, the shape of the pegs 70 is changed and they are designed, for example, to be shortened and / or conical. In a variant not shown in more detail, the pegs 70 are enlarged so that the polymer layer 64 has microstructures instead of nanostructures 68. In other words, the size of the pegs 70 and their distances from one another are increased. However, the shape of the pegs 70 is essentially unchanged.

[0089] The present invention is not limited to the above-described embodiments. On the contrary, other variants of the present invention may also be derived therefrom by those skilled in the art without departing from the subject matter of the present invention. In particular, all individual features described in conjunction with the various embodiments may also be combined with one another in other ways without departing from the subject matter of the present invention.

[0090] Reference numerals list

[0091] 2 Motor Vehicles

[0092] 4 wheels

[0093] 6 Drive device

[0094] 8 Energy storage device

[0095] 10 Interface

[0096] 12 Energy storage housing

[0097] 14 Battery Cells

[0098] 16 Anode

[0099] 18 Cathode

[0100] 20 Electrodes

[0101] 22 Bus

[0102] 24 Connector

[0103] 26 Battery housing

[0104] 28 Opening

[0105] 30 Diaphragm

[0106] 32 Inner wall

[0107] 34 Covering elements

[0108] 36 Gas

[0109] 38 Space

[0110] 40 Drying element

[0111] 42 Stabilizing elements

[0112] 44 Other openings

[0113] 46 Cover Wing

[0114] 48 Connection Points

[0115] 50 Porous elements

[0116] 52 floors

[0117] 54 valve

[0118] 56 body

[0119] 58 Stopper

[0120] 60 Spring

[0121] 62 movable joints

[0122] 64 Polymer layer

[0123] 66 bottom

[0124] 68 Nanostructure

[0125] 70 bolts

[0126] 72 Thickening

Claims

1. A battery cell (14) having a battery housing (26), in which a plurality of electrodes (20) are arranged and in which the battery housing has an opening (28), which is covered with a gas-permeable membrane (30), wherein the membrane (30) is covered on the outside with a covering element (34) in order to limit the ingress of material into the battery housing (26).

2. The battery unit (14) according to claim 1, characterized in that: The diaphragm (30) is fastened to the inner wall (32) of the battery housing (26).

3. The battery cell (14) according to claim 1 or 2, characterized in that: The cover element (34) is operated according to a pressure difference between a pressure outside the battery housing (26) and a pressure in a space (38) formed between the cover element (28) and the membrane (30).

4. The battery unit (14) according to any one of claims 1 to 3, characterized in that: The cover element (34) comprises a valve (54).

5. The battery unit (14) according to any one of claims 1 to 3, characterized in that: The cover element (34) comprises a polymer layer (64) having a microstructure or nanostructure (68).

6. The battery unit (14) according to any one of claims 1 to 3, characterized in that: The cover element (34) comprises a plurality of flexible cover wings (46) which overlap each other and at least partially overlap the diaphragm (30), and the cover wings (46) are connected to the battery housing (26) at intervals from each other.

7. The battery cell (14) according to any one of claims 1 to 6, characterized in that A drying element (40) is used to reduce moisture that penetrates into the battery housing (26) through the opening (28).

8. The battery unit (14) according to claim 7, characterized in that: The membrane (30) is covered on the inner side flatly by the drying element (40).

9. The battery unit (14) according to any one of claims 1 to 8, characterized in that: The diaphragm (30) is designed such that it tears when the pressure difference between the pressure outside the battery housing (26) and the pressure inside the battery housing (26) exceeds a limit value.

10. The battery unit (14) according to any one of claims 1 to 9, characterized in that: The membrane (30) lies in the region of the opening (28) against a stabilizing element (42), which has a plurality of further openings (44)) which are each covered by the opening (28).

Images