Battery cell

Abstract

The present invention relates to a battery cell (14) comprising a cell casing (26) in which a plurality of electrodes (20) are arranged. The cell casing has an opening (28) covered by a gas-permeable diaphragm (30), and the diaphragm (30) is covered from the outside by a cover element (34) that restricts the entry of substances into the cell casing (26).

Description

Technical Field

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

[0002] Automobiles are increasingly being driven at least partially by electric motors, and thus such automobiles are configured as electric vehicles or hybrid vehicles. For power supply to the electric motor, a high-voltage battery including a plurality of individual battery modules is usually considered. The battery modules often have the same structure as each other and are electrically connected in series and / or in parallel with each other. As a result, the voltage applied to the high-voltage battery corresponds to several times the voltage provided by each battery module. Each battery module itself often has a plurality of battery cells arranged in a common module casing, and these battery cells are electrically connected in series and / or in parallel with each other.

[0003] Each battery cell also usually has a plurality of galvanic elements. These galvanic elements each have two electrodes, namely an anode and a cathode, a separator arranged therebetween, and an electrolyte having freely movable charge carriers. For example, a liquid is used as such an electrolyte. Alternatively, the battery cell is formed as a solid battery, and the electrolyte exists as a solid. The anode and cathode forming the electrodes of the battery cell usually include a support that functions as a conductor. An active material, which is a component of a layer deposited on the support, also commonly called a conductor, is attached to this conductor. In this case, an electrolyte already exists in this layer or can be introduced later. However, at least the active material is suitable for absorbing working ions, such as lithium ions. Depending on the use as an anode or a cathode, different materials are used for the support, and various types of layer materials are used.

[0004] To protect the galvanic element, the galvanic element is usually placed inside the cell casing of a battery cell, often also called a cell cup in many cases. Also, the cell casing protects the electrolyte, but also other components, from the influence of the environment. To provide a relatively large capacity by each battery cell, usually a plurality of such galvanic elements, usually up to 100, are placed in one common cell casing. To utilize the existing space relatively efficiently and to simplify manufacturing, the individual components of the galvanic element are configured in a planar shape and are stacked on top of each other in the stacking direction, thereby forming a substantially cuboid cell stack. In an alternative embodiment, for example, the separator is configured in a strip shape and a plurality of electrodes are provided on opposite surfaces respectively. This strip is wound up to form a roll, especially a so-called "Jelly Roll".

[0005] Depending on the use and arrangement of the galvanic element, the cell casing is shaped. In this case, the cell casing can be configured to be rigid and can be manufactured, for example, from aluminum. In this case, the shape of the cell casing is, for example, a cuboid shape. A battery cell of such a type is also called a prismatic cell. In an alternative embodiment, the cell casing is made of a film coated around the galvanic element. A battery cell of such a type is also called a so-called pouch cell.

[0006] During operation of the battery cell, i.e., during charging and discharging, there is a risk that gas is generated based on unwanted chemical reactions. Based on this, the pressure within the cell casing increases, and as a result, on the one hand, some electrode regions may have poor ion conduction, and as a result, output losses of the battery cell occur. On the other hand, due to the increased pressure, the cell casing may deform, which may mechanically affect especially the surroundings of the battery cell. When the pressure is relatively high, the cell casing may rupture, which may cause the electrolyte to leak out and the entire battery cell to become unusable. There is also a risk of unwanted chemical reactions between the individual components of the battery cell and the surroundings.

[0007] To minimize such gas formation, a special combination of the individual materials of the electrodes and the electrolyte is required, which on the one hand increases the manufacturing costs. On the other hand, the selection of a less reactive electrode material often involves a reduction in the capacity density and / or the energy density. Alternatively, for example, additional elements are provided within the cell casing to bind and / or react with the generated gas. However, due to the additional elements in the cell casing, the construction space and the weight of the battery cell also increase, so the energy density is reduced.

[0008] The underlying problem of the present invention is to provide a particularly suitable battery cell with advantageously improved operational reliability and / or energy density.

[0009] According to the present invention, this problem is solved by the characterizing part of claim 1. Advantageous developments and configurations are the subject of the dependent claims.

[0010] The battery cell is configured to be rechargeable in particular and is preferably a secondary battery. Preferably, the battery cell is a component of a motor vehicle in a predetermined state. The battery cell is suitable therefor, in particular provided and adjusted. In the predetermined state, the battery cell is, for example, a component of an energy accumulator of a motor vehicle, and this energy accumulator has a plurality of battery cells of such a type. Preferably, in this case, these battery cells are also divided into a plurality of battery modules of the same structure as each other. The battery cells are arranged, in particular, within the casing of the energy accumulator or each battery module and are electrically connected to each other in parallel and / or in series. Thus, the voltage applied to the energy accumulator / battery module is several times the voltage provided by each of the battery cells. Preferably, in this case, all the battery cells have the same structure as each other, which facilitates manufacture.

[0011] Therefore, in particular, the casing of the energy accumulator or each battery module, which forms such a composite of battery cells, is preferably manufactured from metal, for example steel such as special steel, or an aluminum alloy. For manufacture, for example, die-casting, deep drawing, casting press or extrusion press is used. In particular, the casing of the energy accumulator or each battery module is configured to be closed. Preferably, an interface forming the terminals of the energy accumulator / battery module is attached within the casing of the energy accumulator or each battery module. In this case, since the interface is in electrical contact with the battery cells, the supply of electrical energy and / or the extraction of electrical energy from the battery cells is possible from the outside of the energy accumulator if a corresponding connector is inserted into the terminals.

[0012] The motor vehicle is preferably a land vehicle, preferably having a specific number of wheels, and at least one of these wheels, in a suitable form a plurality or all of the wheels, is driven by a single drive device. In particular, one, preferably a plurality of the wheels are configured to be controllable. Thus, the motor vehicle is movable without depending on a specific driving path, such as a rail or the like. In this case, preferably, the motor vehicle can be positioned substantially arbitrarily on a driving path, in particular made of asphalt, tar or concrete. The motor vehicle is, for example, a commercial vehicle such as a goods vehicle (Lkw: Lastkraftwagen) or a bus. However, particularly preferably, this motor vehicle is a passenger car (Pkw: Personenkraftwagen).

[0013] By means of the drive device, preferably, the motor vehicle is caused to move forward. For example, the drive device, in particular the main drive device, is at least partially electrically configured, and the motor vehicle is, for example, an electric vehicle. The electric motor is driven, for example, by an energy accumulator configured as a high-voltage battery in a suitable form. By means of the high-voltage battery, preferably a DC voltage is supplied, and this voltage is, for example, between 200 V and 800 V, for example substantially 400 V. Preferably, an electric converter for regulating the power supply to the electric motor is arranged between the energy accumulator and the electric motor. Alternatively, the drive device has an additional internal combustion engine, whereby the motor vehicle is configured as a hybrid motor vehicle. Alternatively, the low-voltage on-board power supply network of the motor vehicle is supplied with power by the energy accumulator, and the energy accumulator provides, in particular, a DC voltage of 12 V, 24 V or 48 V.

[0014] In a further alternative form, the battery cell is a component of an industrial vehicle, industrial equipment, such as tools, in particular a handheld device such as a rechargeable driver. In a further alternative form, the battery cell is a component of an energy supply unit, where, for example, it is used as a so-called buffer battery. In a further alternative form, the battery cell is a component of a portable device, such as a mobile phone, or other wearable devices. Such battery cells can also be used in the camping field, in the model-making field, or for other outdoor activities.

[0015] The battery cell has a plurality of electrodes, i.e., for example, two or preferably more electrodes. In particular, these electrodes are divided into an anode and a cathode, in which case, preferably, half of these electrodes form the anode and the other half form the cathode. However, preferably, there is one more anode than cathode. Particularly preferably, in this case, all the anodes and all the cathodes have the same structure as each other, which simplifies manufacturing. The electrodes are configured, for example, in a planar shape and in particular have a support, also called a conductor. In particular, each support is formed by a metal foil that is at least partially covered by a layer on one or both sides. As the metal of the support / conductor of the cathode, for example, aluminum is used, and as the metal of the conductor of the anode, copper is used.

[0016] In this case, the layer has a thickness of less than 1 mm. Preferably, the thickness of the support is less than 0.1 mm. Preferably, each layer has a conductive additive such as an active material, a binder, and / or conductive carbon black. The active material is used to absorb / releases working ions such as lithium ions, and is suitable, provided, and adjusted for this purpose. As the active material, for the cathode, for example, lithium metal oxides such as lithium cobalt(III) oxide (LiCoO2), NMC, such as NMC622 or NMC811, NCA, LNMO, or Li-rich materials are used. Alternatively, it is a pyrophyllite such as LEP, for example. For the anode, for example, graphite, Si-based materials or mixtures thereof, lithium metal, or LTO are used.

[0017] In particular, the electrodes are substantially rectangular. The electrodes are, for example, stacked on top of each other to form a cell stack, in which case the stacking direction is perpendicular to the extending direction of the electrodes arranged parallel to each other. In this case, the anode and the cathode preferably appear alternately in the stacking direction of the cell stack. Preferably, one separator of the cell stack is arranged between adjacent electrodes, i.e., in particular between one anode and one cathode, and this separator is preferably also configured planar. For example, all the separators have the same structure as each other. In particular, these electrodes are stacked substantially flush with each other, in which case, for example, all the anodes protrude at least slightly beyond the cathode. Therefore, based on the fact that the electrodes are stacked, the cell stack is also substantially rectangular.

[0018] In an alternative embodiment, for example, all the anodes, all the cathodes, or the separators are formed by one common strip, or they are attached to one common strip. Since the strip itself is rolled into a cylindrical shape or the like, a so-called "jelly roll" is formed.

[0019] The battery cell has a cell casing inside which the electrodes are arranged, i.e., for example, a cell stack or a "jelly roll" is arranged. In particular, the cell casing surrounds a volume of 0.1 dm 3 ~10 dm 3 . For example, additionally, the cell casing is at least partially filled with an electrolyte. The cell casing is preferably configured to be rigid. In other words, the battery cell is, in particular, a prismatic cell. In particular, the cell casing is made of a metal, for example aluminum, i.e., pure aluminum or an aluminum alloy. The cell casing has, for example, a cuboid shape. Alternatively, the cell casing is configured to be flexible and is formed, for example, at least partially, in particular on one or both sides, by a metal foil that is coated. Since the metal foil is wound around the electrodes and the ends of the metal foil are preferably sealed, the outflow of the electrolyte and / or the inflow of ambient air into the cell casing are avoided.

[0020] The electrodes are arranged directly inside the cell casing in particular, whereby the electrodes are applied, for example, directly or via another component, against the inner wall of the cell casing and are thus stabilized by the inner wall. At least, the cell casing serves for the direct protection of the electrodes and / or for preventing contact between the electrodes / electrolyte and the ambient air or other particles. In other words, the electrodes inside the cell casing are preferably not at least completely surrounded by another component, so that the weight and material costs of the battery cell are reduced. In particular, there is no other casing inside the cell casing that surrounds the electrodes. Therefore, it is possible to fill the cell casing substantially completely with the electrodes and, optionally, with a separator that is provided.

[0021] In a suitable form, the cell casing has at least one or two through holes, through which one terminal is respectively guided. By one or more terminals, at least some of the electrodes arranged in the cell casing are electrically contact-connected according to the wiring of the electrodes, so that through one or more terminals, electrical energy can be supplied from the outside of the cell casing to the galvanic element formed by the electrodes and / or electrical energy can be taken out from the galvanic element. When only one terminal is provided, at least some of the electrodes are electrically contacted with the cell casing, and thereby the potential of the cell casing is preset by this electrode. In particular, one or more terminals are electrically insulated from the cell casing, and these terminals are fluid-tightly connected to the cell casing, so that the outflow of the electrolyte is avoided in the area of the terminals.

[0022] The cell casing has an opening configured, for example, in a circular or rectangular shape. In particular, the area of the opening is 50 μm 2 ~15 mm 2 , preferably 0.2 mm 2 ~3 mm 2 The opening is covered by a gas-permeable diaphragm. In particular, since the diaphragm is firmly bonded to the cell casing, the movement of the diaphragm relative to the cell casing is prevented. Since the diaphragm has an area larger than that of the opening, the diaphragm completely overlaps the opening. In particular, the area of the diaphragm is smaller than the area of the surface of the cell casing having the opening, if any. Thereby, the material cost is reduced.

[0023] Preferably, the coupling of the diaphragm to the cell casing is made liquid-tight and / or gas-tight, so that liquid and / or gas is prevented from flowing through between the diaphragm and the cell casing and into the opening. In this case, particularly preferably, the diaphragm is welded to the cell casing with a circumferential weld seam in a suitable form. Alternatively, for example, the diaphragm is joined to the cell casing in a form-fitting and / or material-fitting manner, in particular adhesively. In this case, the opening is preferably completely surrounded by the adhesive or the weld seam. For example, the coupling is carried out directly adjacent to the opening, or a space is formed between the opening and the coupling of the diaphragm to the cell casing, for example the adhesive or the weld seam. Thus, the outflow of gas from the cell casing or the inflow of gas into the cell casing is only possible through the opening, and the gas is guided through the diaphragm.

[0024] In particular, the diaphragm is preferably selected to be permeable at least to CO, CO2, H2 and / or CH4. For example, the passage of such gases through the diaphragm is not blocked at all or only blocked to a relatively small extent by the diaphragm. However, the permeability of the diaphragm is relatively low with respect to moisture, in particular water vapor. In particular, the ratio of the CO2 permeability of the diaphragm to the moisture permeability is at least 0.5 or at least 1 or at least 1.5. Preferably, this ratio is greater than 0.5 and less than 3. In short, the diaphragm is configured such that such gases generated within the cell casing can pass through the diaphragm and reach outside the cell casing through the opening, and for this purpose the opening is utilized. In this case, the diaphragm makes it difficult for moisture, in particular water vapor, to enter the cell casing.

[0025] The diaphragm itself is covered by a cover element that is shifted outwardly, i.e., towards the outside with respect to the cell casing. In this case, at least the part of the diaphragm that covers the opening is covered by the cover element. In particular, the opening is covered by the cover element. In this case, the cover element may also be arranged inside the cell casing, but the cover element is shifted in the direction of the opening with respect to the diaphragm. Alternatively, the cover element is located outside the cell casing. For example, the cover element is in contact with the cell casing and / or the diaphragm, or is spaced apart from one or both of them. In particular, the cover element is at least partially rigid. The cover element serves to restrict the entry of substances into the cell casing, particularly moisture, particularly water vapor, and is suitable and particularly provided and adjusted for this purpose. In this case, the entry of substances into the diaphragm is also preferably restricted by the cover element. In other words, the cover element adjusts, in particular, the amount and / or whether a substance such as a liquid or preferably a gas flows into the cell casing through the diaphragm and the opening. Again in other words, the cover element preferably closes the opening, at least temporarily. At least, the cover element is preferably configured such that the gas flow through the diaphragm and the opening is restricted or at least temporarily restricted by this cover element, and thus adjusted. Preferably, the cover element is fluid-tight, for example, always or at least when in a predetermined state such as when the cover element is in a closed state. In other words, in this state, further flow of liquid, particularly water, is preferably sufficiently excluded in principle and / or due to the structure. The cover element is preferably in a predetermined state as long as no gas is formed inside the cell casing.

[0026] Based on the opening and the diaphragm, the outflow of gas occurring within the cell casing is possible, thereby avoiding the generation of excessive pressure within the cell casing that could cause damage to the electrodes and / or the cell casing. Thus, the operating reliability is improved. For this purpose, only a diaphragm and a cover element that require a relatively small space volume are needed. Furthermore, since the cover element can be arranged outside the cell casing, it does not unfavorably affect the energy density. Based on the cover element, the diaphragm is at least partially protected against environmental influences from outside the cell casing, thus preventing damage to the diaphragm. Also, in particular, in a predetermined state where the cover element completely blocks the inflow and / or outflow of gas, the cover element separates particles from the surrounding environment, for example, at least temporarily / partially, from the diaphragm. Thus, the diaphragm is not loaded with liquid, especially water vapor, from outside the cell casing, and although the permeability of the diaphragm to liquid is reduced but still persists, the intrusion of liquid is completely blocked. On the other hand, when the cover element temporarily allows the outflow of gas from the cell casing, during this period, for example, the intrusion of water into the diaphragm is also possible, but this is a relatively small amount and is substantially completely retained by the diaphragm. Thus, the intrusion of water into the cell casing is almost completely blocked.

[0027] The diaphragm is especially made of a polymer, for example, a film, such as a polymer film. In a suitable form, the diaphragm is made of or consists of PTFE, that is, polytetrafluoroethylene. Preferably, the diaphragm has a crystallinity of 85% to 100% and 0.2 g / cm 3 ~2 g / cm 3has a density. When selecting such materials, gas permeability is provided. In this case, the diaphragm prevents or at least makes it difficult for moisture, especially water vapor, to enter the cell casing. In particular, as the diaphragm, the diaphragm described in International Publication No. WO 2012 / 079163 is used.

[0028] For example, the opening is arbitrarily positioned in the cell casing. However, particularly preferably, when the battery cell is configured as a pouch cell, the opening is located in a region near the conductor at one of the cylindrical ends, in a region where the foil that may exist is particularly sealed (for example, on the so-called gas pocket). In this case, the opening is preferably shifted inward from each end by up to 1 / 3 of the maximum length of the cell casing.

[0029] When the battery cell is a prismatic cell, preferably, the opening is present particularly in a region of the end face and / or the narrow-width face that is not parallel to the electrodes that may be stacked to form a cell stack. Alternatively, the opening is located on the side surface of the cell casing that is parallel to the electrodes, but preferably in the edge region, that is, shifted inward from the edge by up to 1 / 3 of the width of this side surface. Such a position of the opening simplifies the structure and does not require changing the existing design of the cell stack. Therefore, further, the opening is arranged in a region where the generated gas accumulates, thereby enabling relatively efficient discharge of the gas through the opening.

[0030] For example, the diaphragm is attached to the outer surface of the cell casing. As a result, the interior space of the cell casing is not filled with the diaphragm, and thus a relatively large volume is provided here for the electrodes. Therefore, the high capacity of the battery cell is still guaranteed. However, particularly preferably, the diaphragm is attached to the inner wall of the cell casing. Thereby, even when the pressure inside the cell casing is relatively high, based on the configuration of the diaphragm, the diaphragm will not bulge excessively outward when rapid gas flow-through is impossible. Therefore, the diaphragm is stabilized by the inner wall, thereby enhancing its robustness. Furthermore, the diaphragm is pressed against the inner wall under excessive pressure, and thus the gas flow between the cell casing and the diaphragm is blocked. As a result, only the outflow of gas through the diaphragm is possible, and thus this is carried out in a controlled manner. In short, particularly the diaphragm is arranged on the surface of the cell casing facing outward or inward.

[0031] For example, the cover element is operated depending on the temperature. In this case, the cover element is preferably configured such that gas inflow and / or gas outflow are completely blocked at a temperature below the threshold value, thereby preventing the diaphragm from being loaded by fluid from the outside of the cell casing by the cover element. On the contrary, when the temperature of the battery cell is higher than the threshold value, the cover element is particularly adjusted such that gas outflow from the cell casing is not blocked by this cover element. In other words, the diaphragm is released. However, as a result, moisture, particularly water vapor, may reach the diaphragm from the outside of the cell casing.

[0032] In this case, the boundary value is preferably 25 °C to 60 °C. Therefore, based on such a boundary value, the cover element is adjusted such that gas can escape only when the battery cell is operating, i.e., only when electrical energy is supplied to the battery cell and / or withdrawn from the battery cell. Only during this period is there a possibility of the generation of gas to be escaped. On the other hand, when the battery cell is not required, the diaphragm is protected by the cover element.

[0033] Alternatively or in combination with this, the cover element is operated in response to the differential pressure between the pressure outside the cell casing and the pressure in the space formed between the cover element and the diaphragm. In particular, the volume of this space is less than 4 cm 3 less than, 1 cm 3 less than or 0.5 cm 3 less than. The pressure in the space between the cover element and the diaphragm is in particular the same as the pressure inside the cell casing or slightly lower than this based on the diaphragm.

[0034] The cover element is operated in particular such that gas can flow out of the cell casing or at least can do so more easily when the pressure in this space is greater than the pressure outside the cell casing, for example by 0.1 bar, 0.5 bar, 1 bar, 2 bar or 5 bar. Otherwise, the cover element is in particular closed, thereby completely preventing gas outflow. In this case, the diaphragm is also protected by the cover element against liquid from outside the cell casing. Thus, the protection of the diaphragm by the cover element is reduced only when the pressure on the side of the cover element facing the inside of the cell casing is increased compared to the pressure outside the cell casing. However, in this case, the gas flow direction is directed towards the outside of the cell casing. Thus, based on the gas flow direction, the ingress of liquid up to the diaphragm is prevented. When the differential pressure decreases, the gas velocity also decreases, so that ingress of moisture, in particular water vapor, may become possible. However, in this case, the cover element is closed again, thereby likewise preventing the ingress of liquid.

[0035] For example, the cover element is a porous element or includes a porous element, in which case the pores are particularly open. For example, the porous element is a foamed ceramic. The porous element increases the path length through which the gas must travel, thereby increasing the resistance to the outflowing gas. Thus, the gas outflow from the cell casing is restricted by the porous element. In this case, based on the porous element, the ingress of moisture, particularly water vapor, is also prevented or at least made difficult, particularly based on capillary action. For example, the porous element is configured to be completely liquid-impermeable and / or gas-impermeable at least in a predetermined region, for example on one side, thereby further increasing the distance that the gas and liquid must travel and thus the fluid-technical resistance. Thus, in particular, the side of the porous element opposite the opening is configured such that the distance that the gas / liquid must travel is made relatively long by the porous element. In particular, the porous element is substantially cuboid in shape, which facilitates manufacture.

[0036] Particularly preferably, the cover element includes a valve or is formed by a valve. This valve is operated using an actuator such as a piezo actuator, for example. Thereby, it is possible to control the gas outflow from the cell casing depending on specific conditions, particularly a differential pressure that may occur in some cases, for example. Preferably, the cover element has a sensor and the actuator is controlled depending on the sensor. Alternatively, the valve is spring-loaded, for example, and is particularly configured as a check valve. In this case, the valve is operated depending on the differential pressure between the pressure existing particularly outside the cell casing and the pressure in the space formed between the cover element and the diaphragm, i.e., when the pressure exceeds a predetermined boundary value. In this case, by replacing the spring, adaptation to various different fields of use and / or other settings becomes possible.

[0037] For example, the valve is a non-permeable body for gases and liquids, such as a diaphragm-shaped / diaphragm-form body. By means of this body, for example, when the cover element / valve is in the closed state, the opening or diaphragm is completely covered. By moving longitudinally, particularly in a direction perpendicular to the direction of extension of the body and / or the diaphragm, the cover element is shifted to the open state, and this body is preferably supported accordingly. In this case, based on the longitudinal movement, even in the open state of the cover element, direct ingress of liquid into the opening is prevented. Alternatively thereto, the cover element is configured in the form of a flap and is thus rotatable, in particular with respect to the cell casing, and / or is supported by the cell casing. For example, in this case, the body that may be present is supported by the cell casing by means of a bearing or particularly preferably by means of a film hinge. This simplifies the structure.

[0038] Alternatively thereto, the cover element has a polymer layer that is directly adhered to another body, preferably plastic, for example in the form of a film. In this case, the polymer layer includes microstructures or nanostructures, i.e., structures having an extension of 100 μm to 1 nm. In particular, since this structure is periodically repeated, one pattern is formed. This facilitates manufacturing. The structures are, for example, flaps and / or turf-like members. In the case of turf-like members, these are particularly directed away from the inside of the cell casing, so that when the pressure outside the cell casing is increased or when liquid impinges on the cell casing, this structure is pressed flat against the bottom of the polymer layer, so that the cover element is configured relatively tightly. Alternatively or in combination therewith, the structure is adjustable, for example by applying a voltage, whereby the passage of gases and liquids is made possible or blocked. The microstructures or nanostructures improve the mechanical robustness and reduce the required space.

[0039] In another alternative embodiment, the cover 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 10, whereby the structure is simplified. The cover wings are coupled to the cell casing, i.e., for example, directly attached to the cell casing or indirectly attached via another element. In this case, the cover wings are coupled to the cell casing at different locations from each other, i.e., at their respective attachment points, i.e., spaced apart from each other. In particular, these attachment points surround the opening. In a suitable form, the cover wings are simply attached on one side. The cover wings at least partially overlap the diaphragm, i.e., in particular also the opening or at least the part of the diaphragm covering the opening. Furthermore, the cover wings overlap each other. In reduction, each one of the cover wings of the cover wings at least partially covers one or more of the other cover wings.

[0040] The cover wings are configured to be flexible, i.e., elastically deformable. In particular, the cover wings are composed of a gas-impermeable and liquid-impermeable material. Based on the flexible configuration of the cover wings, the cover wings can be bent, whereby the diaphragm is released. In this case, the cover wings are stabilized with respect to each other, so that on the one hand, an unintentional bending of one of the cover wings does not cause the release of the diaphragm. The force required for this is also relatively high. Furthermore, based on the mutual overlap, a relatively large creepage distance is provided, so that the ingress of liquid between the cover wings is substantially prevented from reaching the diaphragm. In this case, the outflow of gas in the reverse direction is substantially prevented in the cover wings applied to the cell casing. However, by bending all the cover wings or at least some of the cover wings, the diaphragm can be released and thus gas outflow can be enabled.

[0041] Particularly preferably, since the cover wing is coupled to the outer surface of the cell casing, pushing in of the cover wing that may damage the diaphragm is avoided. For example, the cover wing is configured to be bent when the pressure rises on the side of the diaphragm, thereby enabling gas outflow. Alternatively, the cover wing is made of, for example, two different materials that contract in different ways when the temperature rises. Thus, when the temperature rises, the cover wing is bent, and as a result, the diaphragm and thus the opening are also released.

[0042] Particularly preferably, the battery cell has a drying element for reducing moisture that enters the cell casing through the opening. For this purpose, the drying element is suitable, particularly provided and adjusted. Thus, moisture such as water in a liquid or gaseous state that enters despite the cover element is bound based on the drying element, preventing an undesirable reaction with the electrodes and / or optionally the electrolyte arranged in the casing. Thereby, the operating reliability is further improved. In particular, the drying element is configured such that water binding, particularly absorption of water molecules, is performed by 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 coupled to the diaphragm. In other words, the diaphragm is functionalized with silicon-containing groups. Thus, the required space is reduced. Particularly preferably, the drying element is diaphragm-shaped and, for example, loosely placed on the diaphragm or spaced from the diaphragm. Based on being arranged on the inner surface of the diaphragm, only the portion of the liquid, particularly water, that reaches the inside of the cell casing through the diaphragm is retained by the drying element. In other words, first the diaphragm is used to retain the moisture / liquid, and only subsequently is the drying element used. Thus, relatively long-term operation of the battery cell is also possible without loss of function of the drying element.

[0044] For example, the diaphragm is formed to have tear resistance. However, particularly preferably, the diaphragm is configured such that when the differential pressure between the pressure outside the cell casing and the pressure inside the cell casing exceeds a boundary value, the diaphragm tears. Thereby, damage to the cell casing is avoided. For example, the diaphragm tears completely and thus breaks. Preferably, tearing occurs only when the boundary value is exceeded. When the differential pressure falls below the boundary value again, the tearing particularly ends. Thereby, complete destruction of the diaphragm is avoided.

[0045] For example, the battery cell has a plurality of openings, each of which is correspondingly covered by a gas-permeable diaphragm, and each diaphragm is covered from the outside by a correspondingly arranged cover element for restricting the entry of moisture into the cell casing. For example, a plurality or all of the openings are covered by the same cover element. Particularly in this case, all the openings / diaphragms / cover elements have the same structure as each other, and only their positions in the cell casing are different from each other. Alternatively, for example, the cover element and / or the diaphragm are each configured differently, and thus the cover element and / or the diaphragm each have different permeabilities and / or are each operated under different differential pressures or other conditions. Therefore, flexibility is improved.

[0046] However, particularly preferably, the battery cell has only one opening, which facilitates manufacturing. In particular, the diaphragm is in contact with the stabilizing element, at least in the region of the opening, and is, for example, attached to the stabilizing element. In other words, the stabilizing element at least partially covers the opening. The stabilizing element is preferably configured to be rigid and is, for example, manufactured from metal. Preferably, the stabilizing element is fixed to the cell casing in a suitable manner, by welding for example. The stabilizing element has another opening which is covered by the respective opening. Thereby, the effective area available for gas outflow from the cell casing is limited to the sum of the other openings, so that a relatively large opening can also be selected, in which case there will be no excessive gas outflow or inflow of liquid into the cell casing.

[0047] In a suitable form, the stabilizing element is shifted outward compared to the diaphragm. Thus, another opening defines the maximum deformation of the diaphragm, thereby stabilizing the diaphragm. For example, the stabilizing element is configured to break when the differential pressure between the pressure inside the casing and the pressure outside the cell casing is increased. For this purpose, the stabilizing element has, for example, one or more target breaking points, which are manufactured, for example, by laser or embossing. The differential pressure at which this occurs can in this case be adjusted relatively precisely. Alternatively or in combination with this, the stabilizing element is configured to break when a predetermined temperature is exceeded. Based on the breakage, the diaphragm is no longer stabilized and thus is similarly overloaded, so the diaphragm tears. As a result, a relatively large volume of gas can flow through the opening. In particular, the cover element is in this case also adjusted to break or at least to allow gas outflow substantially unhindered. Thus, controlled degassing of the battery cell is carried out and uncontrolled destruction of the cell casing due to excessive pressure is avoided. The battery cell will certainly be damaged thereby and will no longer be usable, but the load on the surroundings is reduced. In other words, the diaphragm and the stabilizing element act in the form of a rupture disk.

[0048] Alternatively or in combination with the above-described embodiments, the cell casing, in a suitable form, has an incorporated target break location. The incorporated target break location is, for example, spatially separated from the opening or, for example, the incorporated target break location has an opening. In another alternative embodiment, the target break location is formed by the opening. For example, the target break location has a surface of the cell casing where the wall thickness is reduced. Alternatively or in combination, the target break location has a surface of the cell casing provided with, for example, indentations and / or notches. In a developed form, the target break location is an additional opening in the cell casing that is closed by a rupture disk. In other words, the cell casing has an additional opening that is completely closed by a rupture disk. In a suitable form, the target break location has a size of 0.01% to 50% of the area of the cell casing. Preferably, the target break location has a size of 0.1% to 40%, particularly 0.3% to 30% of the area of the complete cell casing. For example, the diaphragm has an area 50% larger than the opening.

[0049] For example, the diaphragm is disposed on the inwardly facing surface of the cell casing. In this case, for example, the diaphragm is outside the opening and is not in complete physical contact with the cell casing. In an alternative embodiment, the diaphragm is spaced from the cell casing at a partial surface via a spacer.

[0050] In another alternative embodiment, the cell casing has, for example, an auxiliary opening which is closed by a bursting disc having an opening covered by a gas-permeable diaphragm. The bursting disc is formed, for example, by reducing the wall thickness of the cell casing or is initially a separate component from the cell casing and is attached to the cell casing for assembly. In particular, the bursting disc forms a target breaking point which may be present in some cases. Preferably, the diaphragm is attached to the outward-facing surface of the bursting disc. In this case, for example from the outside, the diaphragm is applied to another or possibly existing stabilizing element which has a plurality of additional openings. Preferably in this case, the stabilizing element is attached to the bursting disc. In an alternative embodiment, the diaphragm is arranged on the inward-facing surface of the bursting disc and the diaphragm is supported on the bursting disc in part via a spacer.

[0051] The invention further relates to a composite of such battery cells, which is preferably a battery module or a high-voltage battery. Furthermore, the invention relates to a motor vehicle, such as a passenger car (PKW), comprising battery cells of such a type, in particular a composite of such a type. The battery cells are used in particular for supplying power to the main drive of the motor vehicle.

[0052] The advantages and developments described with respect to the battery cell are transferred, as appropriate, to the composite / motor vehicle and vice versa, and also to each other.

[0053] Embodiments of the invention are described in detail below with reference to the drawings.

Brief Description of the Drawings

[0054]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

Figure 15

Figure 16

Figure 17

[0055] Parts corresponding to each other are marked with the same reference numerals in all the drawings.

[0056] Figure 1 schematically shows a motor vehicle 2 in the form of a passenger car (Pkw). The motor vehicle 2 has a plurality of wheels 4, and at least some of these wheels are driven by a drive device 6 including an electric motor. Accordingly, the motor vehicle 2 is an electric vehicle or a hybrid vehicle. The drive device 6 has a converter for supplying power to the electric motor. The converter of the drive device 6 is also supplied with power by an energy accumulator 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 accumulator 8, which is inserted into an energy accumulator casing 12 of the energy accumulator 8 formed of special steel.

[0057] Inside the energy accumulator casing 12 of the energy accumulator 8, a plurality of battery modules (not shown in detail) having the same structure are arranged, and these battery modules each include a plurality of battery cells 14. The battery cells 14 of each battery module are, in this case, partially electrically connected in series with each other and partially electrically connected in parallel with each other. The battery modules are also electrically connected in series with each other and / or in parallel. The electrical composite of the battery modules is brought into electrical contact with the interface 10, whereby during operation of the drive device 6, the battery modules, and thus the battery cells 14, are discharged or charged (regenerated). In this case, based on the electrical connection, the 400 V voltage provided at the interface 10 is several times the voltage provided by each battery module and also by each battery cell 14.

[0058] FIG. 2 shows a cross-sectional view of one of the battery cells 14 having the same structure as each other. The battery cell 14 has a plurality of anodes 16 and cathodes 18, and only two of each of these are shown. The anode 16 and the cathode 18 forming the electrode 20 of the battery cell 14 are each configured in a planar shape and are alternately stacked on each other to form a cell stack. In this case, a separator (not shown in detail) is disposed between each adjacent anode 16 and cathode 18. The anode 16 protrudes beyond the cathode 18 on a common one side, that is, each conductor formed by each metal sheet is not present. In this case, in the region of the protrusion, each conductor is released from other components, but in other regions, a layer containing an active material is adhered to each conductor, also called a support. The cathode 18 also protrudes beyond the anode 16. In this case, there are protrusions on the opposite sides of the stack formed by the anode 16 and the cathode 18.

[0059] The protrusions of the anode 16 and the cathode 18 are each welded to a bus bar 22 (tab) made of copper. In this case, one common bus bar 22 is assigned to each of the anode 16 and the cathode 18. The bus bar 22 has one terminal 24 each, and this terminal is guided through a cell casing 26 in which the anode 16 and the cathode 18 are disposed. In other words, the electrode 20 is disposed inside the cell casing 26. The cell casing 26 is configured to be rigid and is made of aluminum, that is, a material containing aluminum. Therefore, the battery cell 14 is a rectangular cell. The cell casing 26 is filled with a liquid electrolyte (not shown in detail).

[0060] FIGS. 3 to 6 schematically show a partially cross-sectional view of the battery cell 14 during operation. The cell casing 26 has an area of 50 mm 2It has an opening 28. In this case, the opening 28 is located on the same wall of the cell casing 26 that also provides a through-hole for one of the terminals 24. Except for the opening 28, the cell casing 26 is configured to be liquid-tight and gas-tight. Therefore, the region between the terminal 24 and the through-hole in the cell casing 26 that is arranged corresponding to this terminal is filled with plastic, which is not shown in detail.

[0061] The opening 28 is covered by a gas-permeable diaphragm 30, which is fixed to the inner wall 32 of the cell casing 26 having the opening 28, specifically by welding or adhesion. In the illustrated example, the diaphragm 30 covers the entire inner wall 32 of the casing 26 and thus also completely covers the opening 28. The diaphragm 30 is at least partially made of PTFE. Therefore, the passage of gases such as H2, CO, CH4, and CO2 through the diaphragm 30 is relatively easy, while the passage of moisture, especially water vapor, and other liquids is made difficult compared to this. The diaphragm 30, that is, the part covering the opening 28, is covered by a cover element 34 on the outside with respect to the cell casing 26. The cover element 34 is located on the outer surface of the cell casing 26 and is attached to the cell casing. The cover element 34 is gas-tight and liquid-tight and functions to limit the inflow of gas into the cell casing 26. Therefore, the cover element 34 completely prevents the intrusion of moisture, especially water vapor, from the surroundings into the opening 28 and thus into the diaphragm 30.

[0062] During operation of the battery cell 14, for example, due to a relatively high load or an undesirable chemical reaction based on undesirable foreign particles, gases 36 such as H2, CO, CH4, and / or CO2 may be formed within the cell casing 26. In this case, since the gas 36 requires a larger volume than the reaction materials, the pressure inside the cell casing 26 increases. As shown in FIG. 4, the gas 36 may flow through the diaphragm 30 into the opening 28, that is, into the space 38 defined by the opening 28 in this embodiment, which is formed between the cover element 34 and the diaphragm 30.

[0063] When the differential pressure between the pressure outside the cell casing 26 and the pressure in the space 38 exceeds a boundary value of, for example, 0.5 bar, the cover element 34 is operated, whereby the cover element is partially opened. Accordingly, gas outflow from the space 38 to the surroundings of the cell casing 26 is effected as shown in FIG. 5. Another gas 36 also flows out from the inside of the cell casing 26 to the surroundings through the diaphragm 30 and the opening 28. In this case, the diaphragm 30 prevents the entry of moisture into the cell casing 26 (see also below).

[0064] Since the gas 36 has been at least partially discharged, when the differential pressure between the pressure in the space 38 and the pressure outside the cell casing 26 drops again, as shown in FIG. 6, the cover element 34 is closed again, so that no further outflow of the gas 36 from the space 38 and thus from the cell casing 26 occurs. Accordingly, thereafter again, the diaphragm 30 is completely covered by the cover element 34, so that the entry of moisture into the opening 28 is prevented.

[0065] Based on the structure of the battery cell 14, the ingress of moisture from the outside of the battery cell 26 into the electrode 20 is only possible if the cover element 34 is operated to allow gas flow. However, in this case, since the gas 36 flows from the inside to the outside of the cell casing 26, based on the flow movement of the gas 36, the ingress of moisture is prevented or at least significantly reduced.

[0066] In an alternative embodiment, the operation of the cover element 34 is additionally or alternatively performed solely depending on the temperature of the battery cell 14. In this case, when the temperature of the battery cell 14 exceeds a threshold value, for example 40 °C, the cover element 34 is operated, thereby enabling the escape of the gas 36.

[0067] The diaphragm 30 is further configured to rupture when the differential pressure between the pressure outside the cell casing 26 and the pressure inside the cell casing 26 exceeds (another, higher) threshold value. This threshold value, i.e., another threshold value, is 10% - 25% lower than the maximum pressure load of the cell casing 26, i.e., the differential pressure at which irreversible damage to the cell casing 26 occurs. This other threshold value is, in particular, between 6 bar and 8 bar. In other words, the diaphragm 30 acts as a rupture diaphragm that ruptures to avoid damage to the cell casing 26.

[0068] That is, when a relatively large volume of gas 36 is formed, this gas enters the space 38, thereby operating the cover element 34. As a result, the pressure in the space 38 substantially corresponds to the pressure surrounding the cell casing 26, i.e., the pressure outside the cell casing 26. When the differential pressure between the pressure in the space 38 and the pressure inside the cell casing 26 exceeds another threshold value, the diaphragm 30 ruptures while being controlled. As a result, based on the elimination or reduction of the fluid-technical resistance of the diaphragm 30, the escape of the gas 36 from the inside to the outside of the cell casing 26 is accelerated. Thus, damage to the casing 26 due to excessive pressure inside the cell casing 26 is avoided.

[0069] When the differential pressure drops below another threshold value again, the rupture of the diaphragm 30 stops. Most of the gas 36 escapes, so that even when the differential pressure between the surroundings of the cell casing 26 and the pressure in the space 38 drops below the threshold value of 0.5 bar, the cover element 34 is operated again, and thereby the opening 28 is completely covered by the cover element. Thus, the ingress of moisture into the cell casing 26 is again prevented by the cover element 34. Thus, further operation of the battery cell 14 is possible, but based on the rupture of the diaphragm 30, the ingress of liquid becomes at least temporarily and partially possible.

[0070] FIG. 7 shows a variant of the battery cell 14 shown in FIG. 3. In this embodiment, the battery cell 14 has a drying element 40. The drying element 40 consists of a silicon-containing group and is provided as a layer, by which the diaphragm 30 is covered in a planar manner on the inside, i.e., entirely in this embodiment, and thus covered. In other words, the drying element 40 exists as a layer separate from the diaphragm 30. Depending on the drying element 40, the passage of the gas 36 is hardly or only slightly impeded. However, the moisture, i.e., water (vapor), which still reaches through the opening 28 and the diaphragm 30, is bound and / or absorbed by the drying element 40 and thus cannot reach the electrodes 30 and / or the electrolyte. Thus, the drying element 40 serves to reduce the moisture entering the cell casing 26 through the opening 28.

[0071] FIG. 8 shows another variant of the battery cell 14 shown in FIG. 3. In this embodiment, the opening 28 is covered on the outer surface by a diaphragm 30, which is fixed to the outer surface of the cell casing 26, specifically by welding or gluing. Further, the battery cell 14 has a stabilizing element 42 made of metal. The stabilizing element 42 is configured in a planar shape and is entirely applied to the diaphragm 30. Thus, the diaphragm 30 is also applied to the stabilizing element 42 in the region of the opening 28. In this case, the diaphragm 30 is arranged between the cell casing 26 and the stabilizing element 42, and thus the stabilizing element is offset outwardly with respect to the diaphragm 30.

[0072] FIGS. 9 and 10 show embodiments of the stabilizing element 42 in plan view, respectively. This embodiment has a plurality of different openings 44, respectively. In the embodiment shown in FIG. 9, the different openings 44 are provided by circular cutouts, respectively, separately from each other. In the embodiment shown in FIG. 10, the different openings 44 are strip-shaped.

[0073] At least a part of the other opening 44 or the other opening is arranged above the opening 28, and thus the other opening is covered by the opening 28. The stabilizing element 42, and thus also the diaphragm 30, is entirely covered by a cover element 34 arranged outside the cell casing 26 as well. When the pressure inside the cell casing 26 rises and the cover element 34 is at least partially opened, the diaphragm 30 bulges slightly outward only in the region of the other opening 44, thereby avoiding excessive deformation of the diaphragm 30. The stabilizing element 42 breaks only when the differential pressure between the inside and the surroundings of the cell casing 26 exceeds another threshold value, namely 6 bar to 8 bar. Thus, the stabilizing element 42 no longer stabilizes the diaphragm 30, and thus the diaphragm tears, thereby enabling the escape of a relatively large volume of gas 36 without being hindered.

[0074] FIG. 11 shows an embodiment of the cover element 34 in a plan view. The cover element 34 has a plurality of cover wings 46, and these cover wings 46 are each connected, i.e., attached, to the cell casing 26 at connection points 48 spaced apart from each other. The connection points 48 surround the opening 28, and the cover wings 46 are arranged at the ends opposite to their respective connection points 48 so as to at least partially cover each other and the opening 28, and thus also the diaphragm 30. The cover wings 46 are configured to be flexible and are made of, for example, a polymer. When the differential pressure exceeds a threshold value, based on the pressure being increased, the cover wings 46 are lifted from the cell casing 26 at the free ends spaced apart from their respective connection points 48, where otherwise these cover wings are in planar contact, so that gas outflow becomes possible. On the other hand, when the differential pressure is relatively small, the gas outflow from the inside of the cell casing 26 and / or the ingress of moisture from the outside of the cell casing 26 into the opening 28 or at least to the diaphragm 30 is blocked based on the relatively large creepage distance provided by the overlap. In an alternative embodiment, the cover wings 46 are made of two different materials having different temperature characteristics. In this case, the material of the portion of the cover wings 46 facing the outer surface of the cell casing 26 is selected such that the cover wings contract strongly when the temperature rises. As a result, at high temperatures, the cover wings 46 are deformed such that the opening 28, and thus the diaphragm 30, is released.

[0075] Figure 12 again shows the battery cell 14 partially in a schematic cross-section. In this embodiment, the opening 28 is again covered from the outside by the diaphragm 30. The diaphragm 30 is also completely covered by the cover element 34, which includes a porous element 50, i.e., a foamed ceramic or a foamed material. The porous element 50 has a plurality of pores that are open but not shown in detail. Through these pores, the flow of gas is possible, in which case the flow of gas is restricted by an increased hydrodynamic resistance.

[0076] On the side opposite to the diaphragm 30, the cuboid porous element 50 is provided with a layer 52 that is completely fluid-tight. This layer 52 ensures that the outflowing gas 36 takes a relatively long path through the porous element 50 in order to flow out, in which case the structural size of the cover element 34 does not become excessively large. Also, the layer 52 ensures that the impinging water similarly reaches the opening 28 only after a relatively long path through the porous element 50, which is relatively significantly delayed based on capillary action.

[0077] FIG. 13 shows another configuration of the battery cell 14 according to FIG. 12. Also in this case, the diaphragm 30 is arranged on the outer surface of the cell casing 26 and covers the opening 28. The cover element 34 is also arranged on the outer surface of the casing 26. The cover element 34 has a valve 54 and is formed by the valve in the illustrated embodiment. The valve 54 has a fluid-impermeable body 56 which is shaped such that when the body 56 abuts against the cell casing 26 at the edge side, the complete diaphragm 30 is surrounded by the body. This body 56 is manufactured from plastic and is supported so as to be longitudinally movable in a direction perpendicular to the surface of the diaphragm 30 by a guide (not shown in detail). Further, this body is supported by a stopper 58 by a plurality of springs 60. In this case, the body 56 is located between the stopper 58 and the diaphragm 30. The springs 60 are configured such that as long as the differential pressure between the pressure inside the casing 26 and the surroundings of the cell casing 26 is less than a boundary value of 0.5 bar, the body 56 is pressed against the diaphragm 30 and the cell casing 26 by this spring. When this boundary value is exceeded, based on the pressure, the body 56 is separated from the diaphragm 30 against the force applied by the springs 60, thereby enabling the escape of the gas 36.

[0078] In an embodiment not shown in detail, the springs 60 are replaced by an actuator or an actuator is additionally provided. An actuator such as a piezo actuator or a magnet element is operated to separate the body 56 from the diaphragm 30 when a predetermined condition such as a predetermined temperature rise occurs.

[0079] FIG. 14 shows an alternative embodiment of the valve 54. In this case, the body 56 is pivotally supported by a hinge 62, for example a film hinge, on another component of the cover element 34 or the cell casing 26. In one aspect, the valve 54 is configured as a check valve, such that liquid coming into contact with the body 56 from the outside closes the valve 54. In an aspect not shown in detail, the body 56 is further loaded by a spring 60, not shown in detail, and when the differential pressure is less than a threshold value, the body 56 is pushed or pulled by this spring into the closed position. In another aspect not shown, the body 56 is additionally or alternatively operated by an actuator.

[0080] FIGS. 15 and 16 show variants of the cover element 34. In an alternative aspect, a polymer layer 64 is deposited on a separate component or another diaphragm is formed by the polymer layer 64. The polymer layer 64 has a bottom surface 66 to which a plurality of nanostructures 68 are attached. These nanostructures 68 are each arranged in a repeating pattern at intervals of 200 nm relative to each other. Each nanostructure 68 has a pin 70 attached to the bottom surface 66 and facing away from the bottom surface, and a thickness portion 72 is coupled to the pin at the free end opposite the bottom surface 66. The dimensions of the thickness portion 72 depend on the applied voltage. In the normal state of the cover element 34, i.e., when no voltage is applied, the thickness portions 72 bulge such that adjacent thickness portions 72 contact each other, thereby making the flow of gas 36 impossible as shown in FIG. 15. In contrast, when a voltage is applied, the thickness portions 72 contract, causing adjacent thickness portions 72 to be spaced apart from each other. As a result, as shown in FIG. 16, the flow of gas 36 is made possible.

[0081] FIG. 17 similarly shows a variant of the cover element 34 formed by the polymer layer 64. However, in this case, the nanostructure 68 is configured as a fine turf-like member. In other words, only the individual pins 70 project from the bottom 66, and these pins are configured to be relatively flexible. In this case, as in the case of the above-described embodiment, the pins 70 face away from the cell casing 26 or outward. When a droplet collides from the outside, the pins 70 are bent toward the bottom surface 66, whereby the pins 70 overlap each other and come into contact with each other. As a result, the passage of moisture is blocked. As soon as the moisture is removed, the pins 70 substantially resume their original positions. The reverse flow of the gas 36 is always possible at the pins 70 directed straight.

[0082] In an embodiment not shown in detail, the shape of the pins 70 is changed, and these pins are, for example, shortened and / or configured in a conical shape. In an embodiment not shown in detail, the pins 70 are enlarged, whereby the polymer layer 64 has a microstructure instead of the nanostructure 68. In other words, the size and the mutual spacing of the pins 70 are enlarged. However, the shape of the pins 70 is not substantially changed with respect to this.

[0083] The present invention is not limited to the above-described embodiments. Rather, those skilled in the art can also derive other aspects of the present invention from here without departing from the subject matter of the present invention. Furthermore, all individual features described in particular in connection with the individual embodiments can be combined with each other in other forms without departing from the subject matter of the present invention.

Description of Reference Numerals

[0084] 2 Automobile 4 Wheel 6 Drive device 8 Energy accumulator 10 Interface 12 Energy accumulator casing 14 Battery cell 16 Anode 18 Cathode 20 Electrode 22 Busbar 24 Terminal 26 Cell casing 28 Opening 30 Diaphragm 32 Inner wall 34 Cover element 36 Gas 38 Space 40 Drying element 42 Stabilizing element 44 Another opening 46 Cover wing 48 Junction point 50 Porous element 52 Layer 54 Valve 56 Body 58 Stopper 60 Spring 62 Hinge 64 Polymer layer 66 Bottom surface 68 Nanostructure 70 Pin 72 Thick part

Claims

1. A battery cell (14), comprising a cell casing (26) in which a plurality of electrodes (20) are arranged, the cell casing having an opening (28) covered by a gas-permeable diaphragm (30), the diaphragm (30) being covered from the outside by a cover element (34) for restricting the entry of substances into the cell casing (26).

2. The battery cell (14) according to claim 1, wherein the diaphragm (30) is attached to the inner wall (32) of the cell casing (26).

3. The battery cell (14) according to claim 1 or 2, wherein the cover element (34) is operated in response to a differential pressure between the pressure outside the cell casing (26) and the pressure in a space (38) formed between the cover element (34) and the diaphragm (30).

4. The battery cell (14) according to any one of claims 1 to 3, wherein the cover element (34) has a valve (54).

5. The battery cell (14) according to any one of claims 1 to 3, wherein the cover element (34) has a polymer layer (64) containing a microstructured or nanostructured body (68).

6. The battery cell (14) according to any one of claims 1 to 3, wherein the cover element (34) has a plurality of flexible cover wings (46) that overlap each other and at least partially overlap the diaphragm (30), the cover wings being spaced apart from each other and coupled to the cell casing (26).

7. The battery cell (14) according to any one of claims 1 to 6, wherein a drying element (40) is provided for reducing moisture entering the cell casing (26) through the opening (28).

8. The battery cell (14) according to claim 7, wherein the diaphragm (30) is covered on the inside in a planar manner by the drying element (40).

9. The diaphragm (30) of the battery cell (14) according to any one of claims 1 to 8 is configured to rupture when the differential pressure between the pressure outside the cell casing (26) and the pressure inside the cell casing (26) exceeds a threshold value.

10. The diaphragm (30) is applied to a stabilizing element (42) in the region of the opening (28), the stabilizing element having a plurality of other openings (44), each of the other openings being covered by the opening (28), of the battery cell (14) according to any one of claims 1 to 9.

Images