Battery cell

Abstract

The present invention relates to a battery cell (14) having a cell housing (26), wherein a plurality of electrodes (20) are arranged in the cell housing (26). The cell housing (26) has a wall (28) with a target breaking region (30), and the target breaking region (30) has an opening (32) covered by a gas-permeable membrane (36). A recess (38) reaching the opening (32) is introduced into the wall (28) of the target breaking region (30).

Description

Technical Field

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

[0002] The number of automobiles that are at least partially driven by an electric motor is increasing, and such automobiles are configured as electric vehicles or hybrid vehicles. In order to supply power to the electric motor, a high-voltage battery including a plurality of individual battery modules is usually used. The battery modules often have the same structure as each other and are electrically connected in series and / or in parallel to each other. As a result, the voltage applied to the high-voltage battery corresponds to a multiple of the voltage supplied by each of the battery modules. Each battery module itself usually has a plurality of battery cells arranged in a common module housing, and these battery cells are electrically connected in series and / or in parallel to each other.

[0003] Each of the battery cells further usually includes 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 containing freely movable charge carriers. For example, a liquid is used as such an electrolyte. In an alternative form, the battery cell is configured 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 current conductor. Usually, an active material is fixed to the support here, and this active material is a constituent member of a layer deposited on the support, also called a conductor. In this case, an electrolyte may already exist in the layer, or the electrolyte may be introduced later. However, at least the active material is suitable for absorbing operating ions, such as lithium ions. Depending on the use as an anode or a cathode, different materials are used for the support, and different materials are used for the layers respectively.

[0004] To protect the galvanic element, this galvanic element is usually arranged within a cell housing, which is also commonly referred to as the cell cup of a battery cell. Also, the cell housing protects the electrolyte from environmental influences. To provide a relatively large capacity for each battery cell, generally, blocks of up to 100 such galvanic elements are arranged within a common cell housing. To more efficiently utilize the existing space and further simplify manufacturing, the individual components of the galvanic element are formed in a planar shape and 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 formed in a strip shape, and a plurality of electrodes are provided on each of the opposing side portions. The strip is wound to form a roll, particularly forming a so-called "jelly roll". Thus, the galvanic element is wound to form a cylindrical shape.

[0005] Depending on the arrangement during use of the galvanic element, the cell housing is shaped. Here, such a cell housing can be formed rigidly, for example, made from aluminum. In that case, the shape of the cell housing is, for example, cuboid. Such a battery cell is also referred to as a prismatic cell. In an alternative embodiment, the cell housing is made by a film provided around the galvanic element. Such a battery cell is also referred to as a pouch cell.

[0006] During the operation of the battery cell, that is, during charging and discharging, gas may be generated based on unwanted chemical reactions. This gas causes the pressure within the cell housing to increase. As a result, on the one hand, the disconnection of the contact of the individual electrodes may occur, which may lead to output loss of the battery cell. On the other hand, due to the increased pressure, deformation of the cell housing may occur, and as a result, there is a risk of mechanical influence particularly on the periphery of the battery cell. When the pressure is relatively high, the cell housing may rupture and the electrolyte may flow out, rendering the entire battery cell no longer usable. Also, unwanted chemical reactions may occur between the individual components of the battery cell and the surroundings.

[0007] To avoid such gas formation, a special selection of the individual materials of the electrodes is required, which on the one hand increases the manufacturing costs. On the other hand, in the case of such materials, the capacity of the battery cell decreases. Instead, for example, additional elements for converging and / or converting the generated gas are provided in the cell housing. In another variation, the cell housing is configured more robustly so that a pressure that would damage the cell housing during operation of the battery cell is never achieved. However, since the additional elements or the robust structure of the cell housing further increase the structural space and weight of the battery cell, the energy density decreases.

[0008] The object underlying the present invention is to provide a particularly suitable battery cell in which the operating safety and / or the energy density is advantageously increased and the manufacturing costs are conveniently reduced.

[0009] Based on the present invention, the above object is solved by the features according to claim 1. Advantageous developments and configurations are the subject of each dependent claim.

[0010] The battery cell is configured in particular to be rechargeable and is conveniently a secondary battery. Preferably, the battery cell is a component of a motor vehicle in a defined state. For this purpose, the battery cell here is suitable for a motor vehicle and is in particular provided and configured for use in a motor vehicle. In a defined state, the battery cell is, for example, a component of an energy accumulator of a motor vehicle having a plurality of such battery cells as described above. Here, preferably, the battery cell is divided into a plurality of battery modules having the same structure as each other. The battery cells are arranged in particular within the housing of the energy accumulator or of each battery module and are electrically connected to each other in parallel and / or in series. Accordingly, the voltage applied to the energy accumulator / battery module is a multiple of the voltage supplied by each of the battery cells. In this case, advantageously, all the battery cells have the same structure as each other, which facilitates manufacturing.

[0011] Therefore, the housing of an energy accumulator or each battery module forming a composite of battery cells as described above is preferably made of metal, i.e., steel, such as stainless steel or an aluminum alloy. For manufacturing, for example, die-casting, deep drawing, injection press or extrusion press is used. In particular, the housing of the energy accumulator or each battery module is configured in a closed state. Conveniently, an interface for forming terminals of the energy accumulator / battery module is introduced into the housing of the energy accumulator or each battery module. The interface is electrically connected in contact with the battery cell, whereby supply of electrical energy and / or extraction of electrical energy of the battery cell from outside the energy accumulator are possible while a corresponding plug is inserted into the terminal.

[0012] The motor vehicle is preferably a land vehicle and preferably has a predetermined number of wheels, at least one of these wheels, preferably a plurality or all, being driven by a drive device. In particular, one of the plurality of wheels, preferably a plurality, is configured to be controllable. Therefore, the motor vehicle is movable without depending on a specific driving path, such as a rail or the like. Here, conveniently, it is possible to place the motor vehicle substantially arbitrarily, in particular on a driving path built of asphalt, tar or concrete. The motor vehicle is, for example, a commercial vehicle such as a truck (Lkw) or a bus. However, particularly preferably, the motor vehicle here is a passenger car (Pkw). Alternatively, the motor vehicle is, for example, a boat, an airplane, a helicopter, a multicopter, a bicycle (electric assist bicycle) or a motorcycle.

[0013] The driving device conveniently causes the vehicle to move forward. For example, the driving device here, especially the main drive mechanism, is at least partially electrically configured, and the vehicle is, for example, an electric vehicle. The electric motor is driven, for example, by an energy storage device configured preferably as a high-voltage battery. The high-voltage battery supplies a DC voltage which is preferably, for example, between 200 V and 800 V, for example substantially 400 V. Preferably, a converter for adjusting the power supply to the electric motor is arranged between the energy storage device and the electric motor. As an alternative, the driving device may additionally have an internal combustion engine, whereby the vehicle may be configured as a hybrid vehicle. In an alternative form, the energy storage device supplies power to the low-voltage on-board power network of the vehicle, and in particular supplies a DC voltage of 12 V, 24 V or 48 V.

[0014] In another alternative form, the battery cell is a component of a forklift, industrial equipment, for example tools, especially a handheld device such as a battery-powered driver. In another alternative form, the battery cell is a component of an energy supply unit, where it is used, for example, as a so-called buffer battery. In a further alternative form, the battery cell is a component of a portable device, for example a mobile phone or other wearable device. The battery cell here can also be used in the camping field, model construction field or other outdoor activities.

[0015] The battery cell has a plurality of electrodes, i.e., for example two electrodes or preferably three or more electrodes. In particular, these electrodes are divided into an anode and a cathode, where advantageously, half of these electrodes form the anode and the other half forms the cathode. However, preferably, there is one more anode than cathode. Particularly preferably, all the anodes and all the cathodes have the same structure as each other, which facilitates manufacturing. The electrodes are configured, for example, in a planar shape and in particular have a support, also referred to as a conductor. In particular, each support is formed using a metal foil whose one or both sides are at least partially coated with a layer. For example, aluminum is used as the metal of the support / conductor of the cathode, and copper is used as the metal of the conductor of the anode.

[0016] In this case, the layer has a thickness of less than 1 mm. Advantageously, the support has a thickness of less than 0.1 mm. Preferably, each layer has an active material, a binder, and / or a conductive additive, such as conductive carbon black. The active material is used for the absorption of operating ions such as lithium ions, is suitable for such absorption, and is provided and configured therefor. As the active material, for the cathode, a lithium metal oxide, such as lithium cobalt(III) oxide (LiCoO2), NMC, such as NMC622 or NMC811, NCA, LMNO, or LFP is used, and / or for the anode, LTO or graphite is used on an Si basis.

[0017] In particular, the electrodes are substantially rectangular. The electrodes are, for example, stacked vertically to form a cell stack, where the stacking direction is perpendicular to the extending direction of the electrodes arranged parallel to each other. At this time, the anode and the cathode are preferably arranged alternately in the stacking direction of the cell stack. Conveniently, one separator of the cell stack is arranged between adjacent electrodes, that is, in particular between one of the anodes and one of the cathodes, and the separators of the cell stack are also preferably configured in a planar shape in the same way. For example, all the separators have the same structure as each other. In particular, the electrodes are stacked vertically so as to form substantially the same plane, where, for example, all the anodes protrude at least slightly beyond the cathodes. Particularly preferably, in this case, the protruding part is enlarged on one of the two side parts. Similarly preferably, the cathode also protrudes beyond the anode on one side part, and the (enlarged) protruding parts are arranged on the opposite side parts of the cell stack. In this way, the contact connection between the anode and the cathode and other components becomes easy. For this reason, based on the stacking of the electrodes, the cell stack also becomes substantially rectangular parallelepiped-shaped.

[0018] In an alternative configuration, for example, all the anodes, all the cathodes or the separators are formed by or fixed to one common strip. Since the strip itself is wound in a cylindrical shape or a shape similar thereto, a so-called "jelly roll" is formed.

[0019] The battery cell has a cell housing, and in this cell housing, electrodes, that is, for example, a cell stack or a "jelly roll" are arranged. Appropriately, the cell housing has a base body in which the electrodes are arranged. Here, the base body is formed, for example, in a pot shape and is closed by a cover of the cell housing. By doing so, the arrangement of the electrodes becomes easy. In particular, the cell housing, preferably the base body, has a volume of 0.1 dm 3 ~10 dm 3Its volume is enclosed. For example, additionally, the cell housing is at least partially filled with electrolyte or the electrolyte is, for example, already partially formed by the respective active materials. The cell housing, in particular the optionally provided base body, is preferably formed rigidly. In other words, the battery cell is a prismatic cell. In particular, the cell housing, preferably the base body and / or the optionally provided cover, is manufactured from metal, such as aluminum, i.e. pure aluminum or an aluminum alloy. The cell housing, in particular the base body, has, for example, a cuboid shape. Instead of this, the cell housing and preferably the base body may be configured flexibly and may be formed, for example, at least partially, in particular on one or both sides, using a metal foil coated with a coating. Since the metal foil is wound around the electrodes and the ends of the metal foil are conveniently sealed, the outflow of the electrolyte and / or the ingress of ambient air into the cell housing are avoided.

[0020] Since the electrodes are arranged directly in the cell housing in particular, they abut, for example, directly or via another member, against the inner wall of the cell housing and are thus stabilized by the cell housing. At least, the cell housing is used to directly protect the electrodes and / or to prevent contact between the electrodes or the electrolyte and the ambient air or other particles. In other words, the electrodes in the cell housing are preferably not at least completely surrounded by another member, so that the weight and material costs of the battery cell are reduced. In particular, there is no separate housing surrounding the electrodes in the cell housing. Thus, it is possible to substantially completely fill the cell housing with the electrodes and optionally provided separators.

[0021] Preferably, the cell housing has at least one or two through-holes, and one terminal is electrically connected through each of these through-holes. One or more terminals electrically contact-connect at least some of the electrodes arranged in the cell housing, whereby electrical energy can be supplied from outside the cell casing to the galvanic element formed by the electrodes and / or electrical energy can be taken out from the galvanic element via one or more terminals. If there is only a single terminal, at least some of the plurality of electrodes are electrically contact-connected to the cell housing, and as a result, the potential of the cell housing is set by this electrode. In particular, one or more terminals are electrically insulated from the cell housing, where the terminal is fluid-tightly connected to the cell housing, so that the outflow of the electrolyte in the region of the terminal is avoided.

[0022] The cell housing, in particular the optionally provided base body, has a wall with a target break region. In other words, the wall has a target fracture region. In this case, the wall is formed, for example, flat, or curved or non-flat. Thus, the target fracture region covers a specific surface of the cell housing, in particular of the base body, i.e. a part of the wall. The target fracture region is configured such that when there is a predetermined pressure difference, a break occurs between the inside and the outside of the cell housing, and as a result, in particular, a mass exchange between the inside and the surroundings of the cell housing becomes possible. In this case, the break of the target fracture region is irreversible. For example, when a pressure difference, hereinafter also particularly referred to as burst pressure, is exceeded, the target fracture region is completely destroyed or only partially destroyed. In particular in this case, the area of the target fracture region that breaks and thus opens depends on the actually occurring pressure difference.

[0023] In this case, the cell housing is configured such that when the burst pressure is exceeded, it first breaks in a target fracture region, i.e., only in a part of the wall, while the remaining components of the cell housing, especially those of the base body, remain undamaged. The remaining components are damaged only when a larger pressure difference occurs, and in this case, they break in a particularly uncontrolled state. The burst pressure is preferably smaller than the pressure difference between the pressure inside the cell housing and the pressure outside the cell housing, and is selected such that the destruction (e.g., complete burst or fracture) of the cell housing occurs in an uncontrolled state. Preferably, the burst pressure is 70% - 90%, 75% - 85% or 80% of the above-mentioned pressure difference.

[0024] The target fracture region has an opening, particularly in the central region, i.e., at a position offset inward from the edge of the target fracture region. Preferably, the distance from the opening to the edge of the target fracture region is greater than 1 / 4 of the extent of the target fracture region in each direction. In particular, the opening is exactly located at the center of the target fracture region. The area of the opening is smaller than the area of the target fracture region, and in particular, smaller than 50%, 20%, 10%, 5%, 1% or 0.1% of the area of the target fracture region.

[0025] The opening is covered by a gas-permeable membrane. In particular, the membrane is firmly, i.e., immovably, attached to the cell housing, preferably the base body and / or the target breaking region, so that movement of the membrane relative to the cell housing or the base body is avoided. The area of the membrane is at least equal to the area of the opening, or preferably is formed larger than the opening so that the membrane completely overlaps the opening. Preferably, the membrane is arranged so that liquid and / or gas is prevented from passing between the membrane and the target breaking region. In other words, the membrane is attached to the cell housing in a gas-tight and liquid-tight manner, for example directly or via another component. For this purpose, particularly preferably, the membrane is welded to the cell housing, for example the target breaking region, preferably by a circumferential welding seam. For this purpose, for example, ultrasonic welding, laser welding or thermal welding methods are used. Instead of this, for example, the membrane is attached to the cell housing by form-fit and / or material-fit, in particular adhesively. In this case, the opening is preferably completely surrounded by an adhesive or a welding seam. For example, the attachment can be carried out so as to be in direct contact with the opening, or can also be carried out so as to be spaced apart between the opening and the attachment of the membrane to the cell housing, for example from the opening to the adhesive part or the welding seam part. Thus, the outflow of gas from or into the cell housing is only possible through the said opening, where the gas is also conducted through the membrane.

[0026] In particular, the membrane is selected to be permeable to CO, CO2, H2, and / or CH4. For example, the membrane hardly or only relatively slightly blocks the passage of these gases. However, the permeability of the membrane is advantageously significantly lower with respect to moisture, especially water vapor. In particular, the ratio of the CO2 permeability to the moisture permeability of the membrane is at least 0.5, at least 1, or at least 1.5. Preferably, the above ratio is greater than 0.5 and less than 3. In particular, the membrane acts as a barrier against the ingress of moisture, especially water vapor, into the cell housing. In summary, the membrane is configured such that these gases generated within the cell housing can reach outside the cell housing through the opening, and for this purpose, the opening is utilized. Here, the membrane makes it difficult or significantly reduces the ingress of moisture and liquid, especially water, into the cell housing.

[0027] The membrane is particularly manufactured from a polymer, for example, manufactured as a film, for example, a polymer film. Preferably, the membrane is manufactured from or consists of PTFE, i.e., polytetrafluoroethylene. Conveniently, the membrane has a crystallinity of 85% to 100% and a density of 0.2 g / cm 3 to 2 g / cm 3 In such a case of material selection, gas permeability is obtained, and in this case, the membrane prevents or at least makes it difficult for moisture, especially water vapor, to enter the cell housing. Membranes suitable for battery applications are described in International Publication No. WO 2021 / 079163. For example, the membrane is formed flat. By doing so, the manufacturing is simplified and the weight is reduced.

[0028] The wall having the target breaking area is provided with a recess, and thus, this recess is located in the target breaking area. In particular, in this case, the recess is located only in the target breaking area. Due to the recess, the strength of the wall, i.e., the wall thickness, is reduced, and in this case, the recess is provided only locally. Preferably, the recess extends along a section formed, for example, in a linear, wavy, curved or other shape. Preferably, the recess is formed in a vertically elongated shape. For example, the recess is a notch and particularly has a V-shaped cross-section. Instead of this, the recess may be formed in the form of a bead or a groove. Since the recess reaches the opening, at least a part of the edge of the opening has shifted to the recess and / or has a part of the recess.

[0029] Based on the gas-permeable membrane, substantially continuous degassing of the cell housing is possible, thereby avoiding or slowing down the formation of a pressure difference between the pressure outside the cell housing and the pressure inside the cell housing, particularly based on the undesired generation of gas inside the cell housing during the operation of the battery cell. At this time, based on the relatively small area of the opening, on the one hand, the mechanical integrity of the cell housing is reduced only slightly. On the other hand, only in this area, the intrusion of foreign substances into the cell housing, such as moisture or liquid, is basically possible, but this is with a relatively low probability. Therefore, a relatively reliable operation of the battery cell is possible over a relatively long period, thereby improving the operation safety. In other words, if there is no obstacle to the operation of the battery cell, due to the substantially continuous degassing through the membrane, gas is not excessively collected in the cell housing, so the pressure difference between the periphery of the cell housing and the inside of the cell housing remains relatively small.

[0030] However, for example, during overload, based on an undesirable chemical reaction within the cell housing, the pressure difference rises relatively strongly and rapidly. As a result, if the generated gas cannot be sufficiently discharged through the opening and the membrane, the target rupture area ruptures, and the cell housing is opened at a specified location, i.e., the target rupture area. Therefore, uncontrolled damage to the cell housing and its uncontrolled impact on the surroundings are avoided. Rather, such ruptures occur only in the area of the target rupture area, so the incorporation conditions of the battery cell can be adapted to this area. Thereby, the operating safety is improved.

[0031] In this case, the break or tear starts in the area of the recess that forms the mechanical weak part of the wall. Since the recess reaches the opening, the initial force cost for this is reduced. Therefore, on the one hand, the recess reaching the opening ensures that when the burst pressure is exceeded, a tear always actually occurs in the target rupture area, thereby improving safety. On the other hand, based on the recess reaching the opening, a tear or break starts at the opening and extends along the recess. For this reason, the shape of the tear is also set. For this reason, when the burst pressure is only slightly exceeded, the target rupture area does not completely tear, but only cracks partially along the recess, so in some cases, the subsequent operation of the battery cell is also possible.

[0032] For example, the target rupture area has a reduced wall strength compared to the rest of the wall. In this case, however, the wall strength is further reduced in the area of the recess, i.e., the wall thickness is reduced. This ensures that when the burst pressure is exceeded, the wall tears only in the area of the target rupture area. Alternatively, the target rupture area may have a wall thickness substantially equal to the rest of the wall, excluding any recesses or other local wall thickness reductions that may occur. This makes manufacturing easier. Also, when mechanical loads occur during installation, no damage occurs, thus increasing robustness.

[0033] Particularly preferably, the target breaking region is integral with the remaining part of the wall and is preferably integrally formed with the remaining part of the wall in a primary molding. In other words, the target breaking region is not formed by an initially separate structural part inserted into the recess of the corresponding wall. This facilitates manufacturing. For example, the recess can already be obtained during the primary molding of the wall or, preferably, later, for example, by etching, laser or engraving. By doing so, the manufacturing of the battery cell becomes easier. To manufacture the battery cell, in particular, first a cell housing having a wall (as a whole) is produced, and for this purpose, for example, an extrusion molding method is used. Then openings and recesses are introduced into the wall, and thus these openings and recesses are not produced by the primary molding of the wall. Next, the openings are covered by a membrane, and this membrane is preferably fixed to the cell housing.

[0034] For example, the membrane is fixed to the outer surface of the cell housing / wall, for example, the outer surface of the target breaking region or the base body provided optionally. By doing so, since the inner chamber of the cell housing is not filled by the membrane, a relatively large volume for the electrodes is available in this inner chamber. Thus, the capacity of the battery cell is increased. Also, by doing so, the area of the membrane can be selected to be larger than the area of the opening. Thereby, after the gas passes through the opening, an enlarged surface for the gas to pass through the membrane becomes available.

[0035] In an alternative form, the membrane is disposed on a surface facing the inside of the target rupture region. In other words, the membrane is offset inward of the cell housing with respect to the target rupture region. By doing so, even when the pressure inside the cell housing is relatively high and immediate gas passage based on the configuration of the membrane is not possible, the membrane does not expand excessively outward. In this case, the membrane is at least partially pressed against the surface facing the inside of the target rupture region. Therefore, the membrane is stabilized by the target rupture region, which enhances robustness. Also, gas passage between the target rupture region and the membrane is prevented, thereby enhancing the sealing property in this region.

[0036] Preferably, the opening is covered by another gas-permeable and hydrophobic membrane, i.e., a membrane that repels at least water. Preferably, particularly when the material of this other membrane is also exposed to air or present in the ambient air, the contact angle of the material of this other membrane with respect to water is greater than 80°, greater than 90° or greater than 100°. Therefore, by this other membrane, moisture is blocked from the membrane, making it even more difficult for moisture to penetrate into the cell housing. Moreover, at least by this other membrane, moisture entering from the outside is also blocked.

[0037] For example, the target rupture region or the opening is optionally positioned in the cell housing. However, particularly preferably, the target rupture region or the opening is located in the region of the cylindrical end close to the conductor in which the film provided in some cases is sealed (e.g., in a so-called gas pocket) when the battery cell is configured as a pouch cell. Here, the target rupture region or the opening is preferably offset inward by up to 1 / 3 of the maximum length of the cell housing from each end at most.

[0038] When the battery cell is a rectangular cell, preferably, the target breaking region or the opening is present in the region of the end face and / or the narrow-width face, but the end face and / or the narrow-width face are not particularly parallel to the electrodes laminated on the cell stack provided as the case may be. Instead, the opening may be in the edge region of the cell housing that is parallel to the electrodes, preferably offset inward from the edge by up to one-third of the width. Based on the position of such an opening, the structure becomes simple and there is no need to change the existing design of the cell stack. Therefore, further, the target breaking region / opening is arranged in the region where the generated gas is collected, thereby enabling more efficient discharge of the gas through the opening.

[0039] The target breaking region is formed, for example, in a stadium shape, a circular shape, or a rectangular shape. In particular, the area of the target breaking region is 0.01 cm 2 ~20 cm 2 , preferably 0.1 cm 2 ~10 cm 2 . Preferably, the target breaking region has a size of 0.01% to 50% of the area of the cell housing. Preferably, the target breaking region has a size of 0.1% to 40%, particularly 0.3% to 30% of the total area of the cell housing. For example, the membrane has an area 50% larger than the opening. Preferably, the opening has an area of 50 μm 2 ~15 mm 2 , advantageously an area of 0.2 mm 2 ~3 mm 2 .

[0040] Preferably, the target breaking region is defined by another recess. In other words, the edge of the target breaking region is at least partially formed by another recess, and thus at the edge of the target breaking region, the wall thickness is locally reduced by the other recess. Therefore, due to the other recess, the wall is similarly structurally weakened, so that even when the burst pressure is exceeded, a crack enters along the other recess, and thereby the target breaking region is opened even on the edge side.

[0041] For example, due to the above-mentioned another recess, only a part of the edge of the target breaking region is formed. Therefore, when the burst pressure is exceeded, the wall tears along the above-mentioned another recess, and tearing along the part of the edge of the target breaking region that does not have the above-mentioned another recess is suppressed. Therefore, even when the above-mentioned another recess is completely torn, the component of the target breaking region remains on the wall and curves outward, thereby forming a kind of film hinge. Therefore, the uncontrolled movement of the individual fragments of the wall is avoided, thereby preventing damage to the structural part surrounding the periphery. Instead of this, the above-mentioned another recess may extend annularly, and the entire target breaking region may be surrounded by this another recess. Here, when the burst pressure is exceeded and the entire another recess tears, the entire target breaking region detaches from the remaining part of the wall, thereby enabling relatively rapid pressure compensation. Therefore, further destruction of the cell housing in an uncontrolled state is avoided, improving the operating safety.

[0042] For example, the recess is arranged at a distance from another recess. However, particularly preferably, the recess reaches another recess. In other words, the two recesses are transitioning into each other. Therefore, when the burst pressure is exceeded, the tearing of the recess starts at the opening and this tearing is led to another recess, whereby this another recess subsequently tears in the same way. In summary, the tearing of the target breaking region starts at the opening, extends along the recess to another recess, and subsequently extends along this another recess. In this way, the cost of the force required for the initial tearing of another recess is reduced. Therefore, it is guaranteed that the target breaking region tears at least partially on the circumferential surface side, thereby releasing a relatively large part of the wall. Thereby, relatively rapid pressure compensation is realized.

[0043] For example, the angle formed between the recess and another recess is arbitrary, or for example, it is 90°. However, particularly preferably, the angle formed between the recess and another recess is greater than 110°, that is, the angle in the region of the transition portion. Conveniently, the angle is greater than 140° or greater than 170°. In this case, the intersection of the recess and another recess forms the vertex of the angle. By doing so, it is ensured that the breakage of the recess propagates to another recess, and the cost of the force for the initiation of the breakage of another recess is reduced. For example, the above-mentioned recess and / or another recess are linear in the region where they are in contact with each other. However, particularly preferably, the transition portion between them is curved. By doing so, the cost of the force for the initiation of the breakage of another recess is further reduced, so that once the breakage starts, this breakage will surely continue immediately.

[0044] For example, the target breakage region has only the recess and optionally another recess. However, particularly preferably, additional recesses reaching the opening are provided on the wall of the target breakage region. Here, due to the additional recesses, local wall thickness reduction portions are similarly formed. Therefore, when the burst pressure is exceeded, the target breakage region is also opened along the additional recesses, and thus most of the target breakage region is released relatively quickly, enabling rapid pressure compensation. Preferably, the additional recesses are located on the side opposite to the opening with respect to the above-mentioned recess. In particular, the above-mentioned recess and the additional recess form an angle, and here, the opening forms the vertex of an angle greater than 160° or greater than 170°. Preferably, the angle here is 180°. Preferably, the above-mentioned recess and the additional recess are formed in an S shape and are connected to each other point-symmetrically with respect to, for example, the opening. For this reason, when the burst pressure is exceeded, a relatively large area is quickly released.

[0045] Preferably, when additional recesses are provided, these additional recesses also reach up to another recess. Thus, the rupture of the other recess starts at two different locations, namely in the region of the intersection with the recess and in the region of the intersection with the additional recess, and the area that is released within a predetermined time due to the rupture / breakage is further enlarged. For example, only the above-mentioned recess and the said additional recess are provided, and these recesses reach up to the opening. Particularly preferably, another additional recess as described above is provided, and this another additional recess also reaches up to the opening, so that after the burst pressure is exceeded, the area released within a predetermined time is further enlarged.

[0046] For example, the cell housing has only a single opening covered by a membrane. Alternatively, the cell housing may have a plurality of such openings each covered by a membrane. In this case, the membranes are formed, for example, continuously or corresponding (separate) membranes are associated with each of the openings. In this case, particularly preferably, these membranes are introduced into the same wall.

[0047] Thus, in summary, the battery cell has, in addition to the opening, a second opening and possibly yet another opening. For example, the second opening is arranged outside the target rupture region. However, particularly preferably, the second opening is a component of the target rupture region and is arranged particularly symmetrically with respect to the opening. In this case, the second opening is covered by a membrane or another second membrane, so that in this case too gas passage is possible, but the ingress of moisture into the cell housing is avoided. For example, the edge surrounding the second opening remains intact. In other words, the region around the second opening has a certain wall thickness.

[0048] However, particularly preferably, a second recess reaching the second opening is introduced into the wall of the target rupture region. For example, the second opening and / or the second recess is formed with the same structure as the opening or the recess. Alternatively, the second opening and / or the second recess may be different, for example, in terms of their dimensions, so that different optimizations can be performed. Therefore, based on the second opening and the second recess, when the burst pressure is exceeded, the target rupture region also ruptures at that location. Thus, after the burst pressure is exceeded, the area released within a predetermined time is further enlarged, and moreover, no excessive structural weakness of the cell housing occurs during normal operation, nor does ingress of foreign particles into the battery cell occur. Also, the manufacturing cost increases little or not at all, and the second opening and the second recess are introduced into the wall, particularly in the same working step as the opening and the recess.

[0049] For example, an additional second recess reaching the second opening is provided, whereby further tearing in various directions starting from the second opening is performed. When another recess is provided, particularly the second recess reaches this another recess, whereby tearing is guided to this another recess through the second recess.

[0050] For example, the region of the wall between two openings is not damaged. However, particularly preferably, the two openings are connected by a connecting recess. In other words, a connecting recess is introduced into the wall, that is, a local wall thickness reduction part is similarly formed, where the connecting recess extends between the two openings, that is, reaches both of the two openings. Therefore, when the burst pressure is exceeded at the connecting recess, the region between the two openings ruptures, where the tearing particularly starts from the two openings. Here, the speed at which a specific area is released after the burst pressure is exceeded is further increased. For example, the connecting recess is linear, or particularly preferably, wavy or curved. In this way, the length of the connecting recess is increased, so that the gas passage region is enlarged after the burst pressure is exceeded, and thus relatively rapid pressure compensation can be performed. Particularly preferably, a plurality of such second openings and corresponding second recesses are provided.

[0051] In particular, the dimensions of the membrane are smaller than those of the target breaking region (overall). In other words, the target breaking region completely covers the membrane. By doing so, the material cost is reduced. Also, the area of the membrane can be optimized with respect to the required size and the connection to the target breaking region / cell housing, regardless of the dimensions of the target breaking region. Further, after the recesses and openings in the target breaking region are torn, at least a part of the surface covered by the target breaking region will no longer be covered by the membrane, so relatively unobstructed pressure compensation can be performed there. Alternatively, the dimensions of the membrane are larger than those of the target breaking region, and the membrane overlaps the target breaking region. By doing so, even when the membrane is fixed to the cell housing, especially its edge side, there is no impact on the target breaking region.

[0052] For example, the target breaking region includes yet another auxiliary recess that is spaced apart from the above-mentioned opening or another opening. The auxiliary recess extends, for example, to another recess among the existing recesses or is spaced apart from these recesses. The auxiliary recesses that form the structural weak parts of the target breaking region set the shape of the tear, in particular, so that the target breaking region is opened in a desired form. For example, each recess of the target breaking region is different from each other. However, particularly preferably, these recesses have substantially the same depth, which facilitates manufacturing. In this way, when the burst pressure is exceeded, tears without difference occur in these recesses. Therefore, even if one of the recesses malfunctions, it will not affect the remaining part of the structure. Instead of or in combination with this, the cross-sections of the recesses are the same as each other, so that the recesses can also be manufactured using the same tool. As another alternative, at least one of the plurality of recesses may have a different depth respectively. Here, the progress of the tear in the target breaking region can be set and adapted, for example, to the structure surrounding the battery cell in the mounted state.

[0053] The present invention further relates to a composite of such battery cells, preferably a battery module or a high-voltage battery. Furthermore, the present invention relates to an automobile, such as a passenger car (Pkw), comprising such battery cells, in particular such a composite. The battery cells are used in particular for supplying power to the main drive of the automobile.

[0054] The advantages and developments described in connection with the battery cells are significantly transferable to the composite / automobile and vice versa, and the advantages and developments described in connection with the composite / automobile are also significantly transferable to the battery cells.

[0055] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

Brief Description of the Drawings

[0056]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

[0057] Corresponding members are denoted by the same reference numerals throughout the figures.

[0058] FIG. 1 schematically shows a motor vehicle 2 in the form of a passenger car (Pkw). The motor vehicle 2 has a predetermined number of wheels 4, and at least some of these wheels are driven by a drive device 6 including an electric motor. That is, 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 further 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 introduced into an energy accumulator housing 12 of the energy accumulator 8 formed of stainless steel.

[0059] Although not shown in detail, a plurality of battery modules having the same structure are arranged in the energy accumulator housing 12 of the energy accumulator 8, and these battery modules each include a plurality of battery cells 14. The battery cells 14 of each battery module are here partially electrically connected in series with each other and partially electrically connected in parallel with each other. Some of the plurality of battery modules are further electrically connected in series with each other and also electrically connected in parallel with each other. The electrical composite of the battery modules is electrically contact-connected to 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). Based on the electrical connection, the 400V voltage supplied to the interface 10 becomes a multiple of the voltage supplied by each of the battery modules and also by each of the battery cells 14.

[0060] Figure 2 shows a cross-section 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 anodes 16 and cathodes 18 forming the electrodes 20 of the battery cell 14 are each configured in a planar shape and are alternately laminated to form a cell stack, where 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 one conductor is formed by each metal foil. In this case, in the region of the protrusion, each conductor does not include another component, but in other regions, a layer is deposited on each conductor including an active material, also referred to as a support. The cathode 18 also protrudes beyond the anode 16, and here, there is a protrusion on the opposite side of the stack formed by the anode 16 and the cathode 18.

[0061] The protrusions of the anode 16 and the cathode 18 are welded to corresponding bus bars 22 each made of copper. In this case, each one of the plurality of bus bars 22 is associated with the anode 16 and the cathode 18. The bus bar 22 has one terminal 24 each, and the terminal 24 is electrically connected through a rectangular parallelepiped cell housing 26 in which the anode 16 and the cathode 18 are disposed inside. The cell housing 26 is made of aluminum rigidly. Therefore, the battery cell 14 is a square cell. The cell housing 26 is filled with a liquid electrolyte (not shown in detail).

[0062] The cell housing 26 has a wall 28 having a target break region 30, and the wall 28 is 5 cm 2has an area. The target rupture area 30 is configured to rupture when a pressure difference exceeding 1 bar burst pressure occurs between the pressure outside the cell housing 26 and the pressure inside the cell housing 26. As a result, the cell housing 26 is opened and pressure compensation is performed. The burst pressure is, in this case, 90% of the maximum pressure load of the cell housing 26, i.e., 90% of the pressure difference at which irreversible and uncontrolled destruction of the cell housing 26 occurs.

[0063] FIG. 3 shows a schematic plan view of the target rupture area 30, and FIG. 4 shows a schematic cross-sectional view. The target rupture area 30, which is integrally formed with the rest of the wall 28, is stadium-shaped and has an opening 32 and a second opening 34 that penetrate the entire target rupture area 30, i.e., the wall 28. Inside, the opening 32 and the second opening 34 are covered by a gas-permeable membrane 36, which is fixed, for example, by welding, inside the wall 28, i.e., inside the target rupture area 30. In this case, the dimensions of the membrane 36 are smaller than those of the target rupture area 30, but the passage of particles from the inside to the outside of the cell housing 26 and vice versa is only possible through the membrane 36. Since the membrane 36 is formed of PTFE, the ingress of moisture into the cell housing 26 is avoided by the membrane 36. However, it is possible to let, for example, CH4 flow out of the cell housing 26 through the membrane 36 and the opening 32 and the second opening 34.

[0064] In the target rupture area 30, a recess 38 reaching up to the opening 32, i.e., a recess 38 reaching inside the wall 28, is introduced. The recess 38 has a wavy or curved extension characteristic and reaches up to the opening 32. In this case, the recess 38 is partially covered by the membrane 36, and the membrane 36 partially fills the recess 38. The recess 38 is a local wall thickness reduction part of the wall 28 in the target rupture area 30. In this case, the cross-section of the recess 38 is rectangular in the illustrated example.

[0065] Furthermore, the wall 28 of the target breaking region 30 is provided with two additional recesses 40 that reach up to the opening 32, and these recesses 40 also have a wavy or curved extending characteristic in the same manner. The depth of the additional recesses 40 corresponds to the depth of the recesses 38 and is formed in the same manner as the recesses 38 in other respects. In this case, one of the additional recesses 40 is arranged point-symmetrically with respect to the recesses 38 with respect to the opening 32. Thus, the recesses 38 and the said additional recesses 40 are in contact with each other at an angle of 180° at the opening 32. The remaining additional recesses 40 extend at an angle of 90° with respect to the opening, rotationally symmetric with respect to the recesses 38 or the other additional recesses 40.

[0066] Also, the wall 28 of the target breaking region 30 is provided with a second recess 42 that reaches up to the second opening 34, and this second recess 42 has substantially the same structure as the recesses 38 but is offset with respect to the second opening 34. In other words, the extending characteristic of the second recess 42 is equal to the extending characteristic of the recesses 38. Further, two additional second recesses 44 are associated with the second opening 34, and these recesses are introduced into the wall 28 in the target breaking region 30 and reach up to the second opening 34. One of the additional second recesses 44 is point-symmetric with respect to the second recess 42 with respect to the second opening 34, and the remaining additional second recesses 44 are rotationally symmetric with respect to the second recess 42 at an angle of 90° respectively, and the other additional second recesses 44 are rotationally symmetric at an angle of 90° with respect to the second opening 42. The recesses 38 and the additional recesses 40 and the second recess 42 and the additional second recesses 44 always have the same cross-section, the same length, and the same extending characteristic, and here, only the orientation and / or the corresponding relationship with respect to each opening 32, 34 are different.

[0067] The target breaking region 30 is defined by another recess 46 surrounding it, and thus this another recess 46 forms the edge of the target breaking region 30. Therefore, the extending characteristic of the said another recess 46 is stadium-shaped, and in this case, the cross-section of the said another recess 46 corresponds to the cross-section of the recess 38. The recess 38 and the additional recess 40 and the second recess 42 and the additional second recess 44 reach up to the another recess 46 and are transitioning into this another recess 46. In this case, based on the curved extending characteristics of the recess 38, the additional recess 40, the second recess 42, and the additional second recess 44, the angle formed by these and the another recess 46 is greater than 110° at the intersection point, and there is a substantially continuous transition portion.

[0068] Furthermore, a connecting recess 48 reaching up to the opening 32 and the second opening 34 is introduced inside the wall 28. In other words, the two openings 32, 34 are connected by the connecting recess 48. The depth and cross-sectional area of the connecting recess 48 correspond to each value of the recess 38. The extending characteristic of the connecting recess 48 is wavy, abutting at an angle of 180° against one of the additional recesses 40 at the opening 32 and similarly abutting at an angle of 180° against one of the additional second recesses 44 at the second opening 34.

[0069] During the operation of the battery cell 14, gas may be generated in the cell housing 26 based on an undesirable chemical reaction. Since such gas can reach the outside from the cell housing 26 through the membranes 36 and the two openings 32, 34, an excessive pressure increase does not occur. Here, when a malfunction or an excessive load occurs, the rate of gas discharge may become insufficient to suppress the pressure increase in the cell housing 26. When the pressure difference between the inside and the outside of the cell housing 26 exceeds the limit value, i.e., the burst pressure, the target rupture region 30 starts to rupture starting from the opening 32, along the recess 38 and the additional recess 40, and also along the connecting recess 48. Also, the target rupture region 30 ruptures along the second recess 42, the additional second recess 44 and the connecting recess 48 starting from the second opening 34. Since the wall thickness is locally reduced, the force cost for starting the rupture is reduced, so that the rupture is always started when the burst pressure is exceeded. Based on the rupture, the area for gas outflow increases, so that the pressure increase is suppressed. If the pressure does not increase further, the rupture stops and the target rupture region 30 remains partially open.

[0070] In addition, even when there is a relatively serious functional failure and the pressure difference further increases, the rupture stops. In this case, the rupture occurs until the entire recess 38, the additional recess 40, the connection recess 48, the second recess 42, and the additional second recess 44 are completely ruptured. The rupture migrates from these recesses to another recess 46, so that another recess 46 also begins to rupture, that is, it ruptures at six different locations. Based on the migration from the individual recesses 38, 40, 42, 44 to another recess 46, in the illustrated example, another recess 46 ruptures clockwise. When another recess 46 is completely ruptured, the individual components of the target rupture region 30 are separated from the remaining part of the wall 28 and peeled off from the wall based on the overpressure in the cell housing 26. That is, there is a relatively large area for pressure compensation, whereby the pressure increase in this case at least stops. Thus, it is prevented that the cell housing 26 ruptures in an uncontrolled state. Therefore, even if the battery cell 14 becomes unusable, other structural parts of the vehicle 2 located around the battery cell 14 are not damaged.

[0071] Figures 5 to 11 show different embodiments of the target rupture region 30 according to the illustration of Figure 3, and these embodiments are always in a stepped shape. Also, each target rupture region 30 is defined by a different recess 46. In the variation shown in Figure 5, the membranes 36 and the two openings 32, 34 are not changed. The connection recess 48, the additional recess 40, and the additional second recess 44 are not provided. The first recess 38 and the second recess 42 are provided so as to reach each opening 32, 34. Here, these openings are formed linearly and extend in the direction of another recess 46 so as to be away from the other opening 32, 34 respectively. At this time, the recess 38 and the second recess 42 are arranged spaced apart from another recess 46. In this embodiment, the surface opened by the rupture of the two recesses 38, 42 first is defined. Therefore, if the pressure increase is relatively small, the operation of the battery cell 14 can continue. Only when the pressure difference is relatively large does another recess 46 rupture, whereby the entire target rupture region 30 is released.

[0072] The deformation mode shown in FIG. 6 of the target fracture region 30 is based on the variation shown in FIG. 5. The difference from FIG. 5 is that the recess 38 and the second recess 42 are extended and formed in a curved state on the end side, so that these recesses are each opened to another recess 46 through a curved portion. Therefore, after the recess 38 or the second recess 42 is completely fractured, the fracture is guided to another recess 46 through each intersection with another recess 46. Thereby, substantially continuous fracture and release of the target fracture region 30 are performed.

[0073] Another deformation mode is shown in FIG. 7. Also in this case, the two openings 32, 34, the membrane 36 and another recess 46 exist without change. The recess 38 further reaches from the opening 32 to another recess 46, and one additional recess 40 is provided symmetrically with respect to the recess 38 with respect to the opening 32. The extending characteristics of the recess 38 and the additional recess 40 are linear here and perpendicular to the extending characteristics of the longitudinal axis of the stadium-shaped target fracture region 30. In other words, the recess 38 and the additional recess 40 each open to another recess 46 at an angle of 90°. The second recess 42 is configured corresponding to the recess 38, and there is one additional second recess 44 formed to correspond to the additional recess 40. In this variation, after the other recesses 38, 40, 42, 44 are completely fractured, another recess 46 starts from the intersections with the other recesses 38, 40, 42, 44 and fractures in two directions, whereby the speed at which another recess 46 is completely fractured is increased.

[0074] The variations shown in FIG. 8 of the target breaking region 30 substantially correspond to the variations shown in FIG. 7. Only another recess 46 is changed and is no longer annular. In other words, yet another recess 46 is divided into two partial sections, and the target breaking region 30 substantially continuously transitions to the remaining portion of the wall 28 at two different locations. These two locations are located at opposite ends along the longitudinal axis of the target breaking region 30, and in this case, the target breaking region 30 is configured axially symmetrically with respect to the longitudinal axis. Based on the interrupted configuration of another recess 46, a part of the components of the target breaking region 30 remains in the remaining portion of the wall 28 even after a complete fracture. These components of the target breaking region 30 curve outward based on the pressure difference with respect to the cell housing 26. In this way, the formation of splits that can cause an undesired interaction with the surrounding components in the battery cell 14 is avoided.

[0075] FIG. 9 shows another embodiment of the target breaking region 30, where the two openings 32, 34 and the membrane 36 are provided without change. The two openings 32, 34 are linear and are connected by a connecting recess 48 extending along the longitudinal axis of the stadium-shaped target breaking region 30. With respect to the opening 32, on the side opposite to the connecting recess 48, a recess 38 curved in an S shape opens into the opening 32. The opposite end of the recess 38 opens into another recess 46. The second recess 42 is configured symmetrically to this and is also S-shaped, so it opens into the second opening 34 at the end of the second opening 34 opposite to the connecting recess 48. Another recess 46 is formed in a shortened manner, starting and opening into the recesses 38 and the second recess 42. Thus, when all the recesses 38, 42, 46, 48 are fractured, a part of the portion of the target breaking region 30 also remains in the remaining portion of the wall 28.

[0076] FIG. 10 shows another embodiment of the target breaking region 30, where another recess 46 is also formed in a ring shape. The membrane 36 is also provided without change. Since the second opening 34 is omitted, only the opening 32 disposed at the center of the target breaking region 30 exists. The linearly formed recess 38 and the linearly formed additional recess 40 open into the opening 32 on opposite sides of each other, that is, at an angle of 180° to each other. The recess and the additional recess 40 each open into another recess 46 at an angle of 120°. In this variation, the manufacture of the target breaking region 30 is simplified.

[0077] FIG. 11 shows the last embodiment of the target breaking region 30, where another recess 46 and the opening 32 are not changed compared to the above-described example. Also, the recess 38 and the additional recess 40 are provided, and these recesses 38, 40 extend linearly and are located on the surface opposite to the side with respect to the opening 32. However, here, the recess 38 and the additional recess 40 are arranged perpendicular to the extension of the target breaking region 30, and thus intersect another recess 46 at an angle of 90°. The membrane 36 is formed to extend in the longitudinal direction and covers the second opening 34 disposed outside the target breaking region 30. Another opening 50 is introduced into the wall 28 symmetrically with respect to the second opening 34 with respect to the mirror surface, and this another opening 50 is also covered by the extended membrane 36. In such a variation as shown in the figure, gas outflow is possible over the entire three openings 32, 34, 50. When the target breaking region 30 tears, the second opening 34 and the other opening 50 are not affected. In the example shown in the figure, the membrane 36 is configured to be narrower than the target breaking region 30. In a variation not shown in detail, the membrane 36 is enlarged, and the entire target breaking region 30 is covered by this membrane 36. Such a configuration of the membrane 36 can also be used in other examples among the above-described examples.

[0078] The variations shown in FIG. 12 substantially correspond to the embodiment shown in FIG. 3. Only the membrane 36 is enlarged, whereby the membrane 36 is larger than the target breaking region 30. Also, the membrane 36 completely overlaps the target breaking region 30.

[0079] The present invention is not limited to the embodiments described above. Rather, those skilled in the art can derive a plurality of other variations of the present invention from these embodiments without departing from the subject matter of the present invention. Furthermore, all the 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.

Explanation of reference numerals

[0080] 2 Automobile 4 Wheels 6 Drive device 8 Energy accumulator 10 Interface 12 Energy accumulator housing 14 Battery cell 16 Anode 18 Cathode 20 Electrode 22 Bus bar 24 Terminal 26 Cell housing 28 Wall 30 Target breaking region 32 Opening 34 Second opening 36 Membrane 38 Recess 40 Additional recess 42 Second recess 44 Additional second recess 46 Another recess 48 Connection recess 50 Another opening

Claims

1. A battery cell (14) having a cell housing (26), wherein a plurality of electrodes (20) are arranged in the cell housing (26), and the cell housing (26) has a wall (28) having a target breaking region (30), wherein the target breaking region (30) has an opening (32) covered by a gas-permeable membrane (36), and a recess (38) reaching the opening (32) is introduced into the wall (28) of the target breaking region (30). Battery cell (14).

2. The battery cell (14) according to claim 1, wherein the target breaking region (30) is defined by another recess (46).

3. The battery cell (14) according to claim 2, wherein the another recess (46) extends annularly.

4. The battery cell (14) according to claim 2 or 3, wherein the recess (38) reaches the another recess (46).

5. The battery cell (14) according to claim 4, wherein an angle formed between the recess (38) and the another recess (46) is greater than 110°.

6. The battery cell (14) according to any one of claims 1 to 5, wherein an additional recess (40) reaching the opening (32) is provided in the wall (28) of the target breaking region (30).

7. The battery cell (14) according to any one of claims 1 to 6, wherein the target breaking region (30) has a second opening (34), and a second recess (42) reaching the second opening (34) is introduced into the wall (28) of the target breaking region (30).

8. The battery cell (14) according to claim 7, wherein the two openings (32, 34) are connected by a connecting recess (48).

9. The battery cell (14) according to any one of claims 1 to 8, wherein the dimension of the membrane (36) is smaller than the dimension of the target breaking region (30).

Images