Battery storage system for an electric vehicle and use of a battery storage system in emergency operation

Abstract

Battery storage system (10) for an electric vehicle (5),- wherein the battery storage system (10) comprises a housing (30), an energy storage cell arrangement (35) with at least one electrical energy storage cell (80) and an emergency protection layer (40, 130),- wherein the housing (30) at least partially encloses a housing interior (56),- wherein the energy storage cell arrangement (35) and the emergency protection layer (40, 130) are arranged in the housing interior (56),- wherein the emergency protection layer (40, 130) is thermally coupled to the energy storage cell arrangement (35) and / or the housing (30),- wherein the emergency protection layer (40, 130) comprises a salt-containing first material with a first melting temperature greater than 600 °C,- wherein the emergency protection layer (40, 130) is designed to, in the event of a thermal emergency and heating of the emergency protection layer (40, 130) to a temperature greater than 600 °C, - characterized by,that- the housing (30) has a housing cover (50),- wherein the housing cover (50) has an inner wall (105) and an outer wall (100),- wherein the outer wall (100) at least partially delimits the housing interior (56),- wherein the inner wall (105) is arranged on the inside of the outer wall (100) and divides the housing interior (56) into a cell space (115) and a layer space (110),- wherein the energy storage cell arrangement (35) is arranged in the cell space (115),- wherein the emergency protection layer (40, 130) is arranged in the layer space (110).

Description

The invention relates to a battery storage system for an electric vehicle according to claim 1 and the use of a battery storage system in an emergency operation according to claim 7. A battery storage system for an electric vehicle is known, comprising a housing and an energy storage cell arrangement with multiple energy storage cells. The energy storage cells are enclosed within the housing and protected from environmental influences such as moisture. The housing can be made of a thermally conductive metallic material. In the event of a vehicle fire, the fire can spread to the energy storage cell arrangement. From DE 10 2022 120 234 A1, a heat barrier component for an electrochemical cell is known, comprising a functional material. The functional material comprises a hydrate of a metal carbonate and / or a hydrate of a metal phosphate. The functional material is designed to release water vapor at a first temperature of approximately 100 °C and to decompose at a second temperature of approximately 300 °C to release a gaseous flame retardant. Energy storage system known from DE 10 2017 008 102 A1. The energy storage system comprises a housing in which several storage cells are arranged, the storage cells being thermally insulated from one another by means of a device arranged between the storage cells. The device is designed such that the storage cells are spaced apart from one another, and the device is made of a temperature-resistant elastic material. From US 2021 / 0013460A1, a fire-resistant laminate is known which has a base material and a fire-resistant resin layer arranged on at least one side of the base material. The fire-resistant resin layer consists of a fire-resistant resin composition, wherein the composition comprises a resin and at least one fire-resistant additive selected from the group consisting of an endothermic agent, a flame retardant, and a thermally expandable layered inorganic substance, and wherein the softening point or melting point of the base material is 300°C or higher. German patent DE 10 2020 007 327 A1 discloses a multi-layered protective element for the thermal and electrical insulation of a battery, a battery with such a protective element, and the use of the protective element to prevent the escape of flames or sparks from a battery. The protective element comprises a carrier layer made of a silicate fabric and a protective layer made of phlogopite. The object of the invention is to provide a particularly fire-resistant battery storage system and an improved method for emergency operation of the battery storage system. This problem is solved by means of a battery storage system according to claim 1 and a use of the battery system in an emergency operation according to claim 7. Advantageous embodiments are specified in the dependent claims. A particularly fire-resistant battery storage system for an electric vehicle can be provided by a battery storage system comprising a housing, an energy storage cell assembly with at least one electrical energy storage cell, and an emergency protection layer. The housing encloses at least a partial interior space, within which the energy storage cell assembly and the emergency protection layer are located. The emergency protection layer is thermally coupled to the energy storage cell assembly and / or the housing. The emergency protection layer comprises a salt-containing primary material with a primary melting point greater than 600 °C. The emergency protection layer is designed to melt upon the occurrence of a thermal emergency and its heating to a temperature greater than 600 °C. The housing comprises a housing cover with an inner wall and an outer wall, the outer wall at least partially delimiting the housing interior. The inner wall is located on the inside of the outer wall and divides the housing interior into a cell space and a layer space. The energy storage cell arrangement is located in the cell space, while the emergency protection layer is located in the layer space. By dividing the housing interior into the cell space and the layer space, the layer space can be sealed fluid-tight from the housing interior. Furthermore, by arranging the emergency protection layer in the layer space, the layer can also be introduced into the layer space using an inlet method. This design has the advantage of making the manufacture of the battery storage system particularly simple. Furthermore, this design has the advantage that, in the event of a vehicle fire outside the battery storage system, while the battery storage system is heated externally by the fire in the housing area, the heat impacting the housing is temporarily absorbed and stored by the emergency protective layer as it melts. This prevents unwanted heating and potential overheating of the energy storage cell array. This ensures that, particularly when lithium-ion cells are used as energy storage cells, a fire that may spread within the vehicle does not also ignite the lithium-ion cells, and provides emergency services with an additional window of time to extinguish the fire and initiate external cooling of the battery storage system. Furthermore, the emergency protection layer ensures that, for example in the event of a defect, particularly thermal overheating of at least one of the energy storage cells, the heat generated by the energy storage cell arrangement is quickly absorbed by the emergency protection layer close to the cell, thereby cooling the energy storage cell arrangement and potentially preventing a vehicle fire. It is particularly advantageous if the emergency protection layer is located at least on the side of the battery storage system facing the passenger compartment, in order to be able to evacuate the vehicle occupants in the passenger compartment in an emergency. In a further embodiment, the emergency protective layer comprises at least one of the following salt-containing first materials: sodium chloride, fluorine-containing salt, boron-containing salt, or halogen-containing salt. Sodium chloride-containing salt has the advantage of being inexpensive and easy to use. In particular, it can be easily pressed into the emergency protective layer. Fluorine-containing, boron-containing, or halogen-containing salt also exhibits excellent fire-resistant properties and is particularly well-suited for extinguishing lithium fires. In a further embodiment, the housing comprises at least one of the following second materials: aluminum, copper, or an aluminum alloy. Additionally or alternatively, the second housing material has a second melting point of less than 600 °C, in particular less than or equal to 550 °C. By using the emergency protection layer, the melting point of the housing can be lower than the first melting point of the salt-containing first material. This makes light metals particularly suitable for use in the housing, allowing the battery storage system to be designed to be especially lightweight thanks to the emergency protection layer. Furthermore, existing standards and requirements for the fire resistance of the housing can also be met with the second material having a second melting point of less than 600 °C in conjunction with the emergency protection layer. In a further embodiment, the battery storage system comprises a cell contacting system arranged on the energy storage cell assembly, which electrically contacts at least one of the energy storage cells. The emergency protection layer is located between the cell contacting system and the housing. This arrangement has the particular advantage that, in the event of a defect in the cell contacting system—for example, if a contact resistance between the energy storage cells and the cell contacting system decreases over the lifetime of the battery storage system, perhaps due to an assembly error combined with vibrations—the emergency protection layer can thermally insulate and, if necessary, cool local hotspots on the cell contacting system, thereby preventing unwanted heating of energy storage cells adjacent to the hotspot. In another embodiment, the emergency protection layer is block-shaped or shell-like and / or comprises at least some sections of the first material in powder form. The block-shaped design has the advantage of being particularly easy to install in the battery storage system. In particular, the emergency protection layer can, for example, be placed on top of the cell contacting system. Alternatively, the emergency protection layer, with its trough-like shape, can at least partially accommodate and enclose the energy storage cell arrangement. The powder-like design has the advantage that the emergency protection layer can be poured into the interior of the housing, filling even small cracks and crevices. Additionally, the emergency protection layer can be particularly elastic and provide vibration damping. In a further embodiment, the energy storage cell arrangement comprises several energy storage cells spaced apart from one another. A gap is arranged between two nearest energy storage cells, with the emergency protection layer located in this gap. The emergency protection layer can, in particular, be in powder form within the gap. Arranging the emergency protection layer in the gap has the advantage that it is positioned very close to the cells, resulting in a particularly short heat transfer path between the emergency protection layer and the energy storage cell. In particular, this effectively prevents local overheating of individual energy storage cells by the emergency protection layer. An improved method for the emergency operation of a battery storage system can be provided by providing a battery storage system. The battery storage system comprises the housing, the energy storage cell assembly with at least one electrical energy storage cell, and the emergency protection layer. The housing encloses at least the interior of the housing, in which the energy storage cell assembly and the emergency protection layer are located. The emergency protection layer is thermally coupled to the energy storage cell assembly and / or the housing. The emergency protection layer comprises the salt-containing first material with a first melting point greater than 600 °C. In emergency operation, the emergency protection layer is heated, at least in certain areas, to a temperature greater than 600 °C. The emergency protection layer melts, at least in certain sections, and protects the energy storage cell assembly.In this process, powdered particles of the first material of the emergency protection layer are melted, and when the emergency protection layer cools below the first melting temperature, the powdered particles are bonded together. This design has the advantage that a large amount of heat can be absorbed by the emergency protection layer through melting, which would otherwise overheat the energy storage cell assembly in an emergency. Therefore, if heat penetrates the battery storage system from the outside, the energy storage cell assembly can be thermally protected from the incoming heat and cooled by the melting process, thus preventing it from catching fire. Conversely, if the energy storage cell assembly is generating heat, vehicle occupants inside the vehicle can be protected by the energy absorbed by the emergency protection layer, and a vehicle fire potentially caused by the energy storage cell assembly can also be prevented. This design also has the advantage that the battery storage system is particularly easy to repair after an emergency, since the damaged area or the former hotspot can be easily located simply due to the melted first material and the interconnected powdered particles of the first material. In another embodiment, heat is introduced into the housing interior via the housing, whereby the heat introduced into the housing interior heats the emergency protection layer to a temperature greater than 600 °C. The emergency protection layer protects the energy storage cell arrangement from the heat, at least temporarily. This thermally insulates the energy storage cell arrangement from the housing. In an emergency, the energy storage cell assembly heats up and warms the emergency protection layer to a temperature exceeding 600 °C. The emergency protection layer absorbs at least some of this heat and stores it by melting. This layer protects the housing from the heat generated by the energy storage cell assembly, at least temporarily. This design has the advantage that the housing, made from a second material with a significantly lower melting point than that of the emergency protection layer, can be manufactured. This allows the use of lightweight metals for the housing, resulting in a particularly light battery storage system. The invention is explained in more detail below with reference to the figures. Figure 1 shows a schematic representation of an electric vehicle with a battery system according to a first embodiment; Figure 2 shows an exploded view of the battery system shown in Figure 1; Figure 3 shows a schematic sectional view along a section plane AA shown in Figure 1 through the battery storage system shown in Figure 1; Figure 4 shows a sectional view along the section plane AA shown in Figure 1 through a battery storage system 10 according to a second embodiment; Figure 5 shows a sectional view along the section plane AA shown in Figure 1 through a battery storage system according to a third embodiment; and Figure 6 shows a schematic sectional view through a vehicle with a battery storage system according to a fourth embodiment. The following figures refer to a coordinate system for ease of understanding. This coordinate system has an x-axis (longitudinal direction), a y-axis (transverse direction), and a z-axis (vertical direction). The coordinate system can, for example, be right-handed. Fig. 1 shows a schematic representation of an electric vehicle 5. The electric vehicle 5 can, for example, be configured as a fully electric vehicle or as a hybrid vehicle. The electric vehicle 5 comprises a battery storage system 10 according to a first embodiment and a drive system 15, which is electrically connected to the battery storage system 10 by means of a first high-current connection 20. The battery storage system 10 is, for example, configured as a traction battery to supply the drive system 15 with electrical energy for propelling the vehicle 5 via the first high-current connection. Furthermore, the vehicle 5 can have a charging port 25 which is electrically connected to the battery storage system 10 by means of a second high-current connection 26 in order to electrically charge the battery storage system 10. In particular, the charging port 25 can be configured to be connected to an HPC charger in order to fast-charge the battery storage system 10. The drive system 15 preferably has a first axle 60 and a second axle 65, wherein at least one of the two axles 60, 65 is driven. A drive motor 70 can be arranged on the axle 60, 65. In this embodiment, for example, both axles 60, 65 are driven, so that the vehicle 5 is configured as an all-wheel-drive vehicle. The battery storage system 10 is arranged in the longitudinal direction (x-direction), which corresponds to the longitudinal direction of the vehicle 5, between the first axle 60 and the second axle 65. In Fig. 1, a passenger compartment 75 is furthermore arranged at least partially between the two axes 60, 65, wherein the passenger compartment 75 is also arranged above the battery storage system 10 in the z-direction. Due to its longitudinal extension, the battery storage system 10 is, for example, arranged below the passenger compartment 75 over large parts of it. The battery storage system 10 comprises a housing 30, an energy storage cell arrangement 35, an emergency protection layer 40 and a cell contacting system 45. The housing 30 has a housing cover 50 (not shown in Fig. 1) and, for example, a housing shell 55. The housing cover 50 and the housing shell 55 enclose a housing interior 56. The energy storage cell arrangement 35, the emergency protection layer 40, and the cell contacting system 45 are arranged in the housing interior 56. The energy storage cell arrangement 35 comprises at least one, preferably several, energy storage cells 80. The energy storage cells 80 are arranged side by side. The energy storage cell 80 can be configured as a lithium-ion cell or a lithium iron phosphate cell. The energy storage cell 80 can also be configured, for example, as a supercapacitor. The geometric configuration of the energy storage cell 80 can be, for example, a cylindrical cell, a punch cell, or a prismatic cell. In this embodiment, one or more electrical energy storage cells 80 are electrically interconnected in series and / or parallel and / or series-parallel by means of cell connectors (not shown in Fig. 1) of the cell contacting system 45.The cell contacting system 45 also provides information about at least one operating parameter of the energy storage cell arrangement 35, for example a temperature and / or an electrical voltage, to a battery management system of the battery storage system 10 in order to ensure safe operation of the battery storage system 10 during both charging and discharging. In this embodiment, the cell contacting system 45 is arranged, for example, in the z-direction on the side facing the passenger compartment 75. Of course, it would also be possible for the cell contacting system 45 to be arranged differently on the energy storage cell arrangement 35. In this embodiment, the emergency protection layer 40 is arranged in the housing interior 56 of the housing 30 on the side of the cell contacting system 45 facing away from the energy storage cell arrangement 35, in the z-direction. The cell contacting system 45 is thus arranged in the z-direction between the emergency protection layer 40 and the energy storage cell arrangement 35. Fig. 2 shows an exploded view of the battery storage system 10 shown in Fig. 1 according to the first embodiment. The emergency protection layer 40 preferably extends completely over the energy storage cell arrangement 35 in both the longitudinal direction (direction of travel) and the transverse direction (y-direction). In the z-direction, the emergency protection layer 40 and the energy storage cell arrangement 35 have an overlap, preferably a complete overlap. An overlap in the z-direction is understood to mean that when two components, for example the emergency protection layer 40 and the energy storage cell arrangement 35, are projected onto a projection plane, which is, for example, configured as an xy-plane, the two components, for example the energy storage cell arrangement 35 and the emergency protection layer 40, overlap in the projection plane in the z-direction. The emergency protection layer 40 can also be referred to as a salt layer and comprises at least one of the following first materials: salt, sodium chloride (NaCl), fluorine-containing salt, boron-containing salt, halogen-containing salt. The first material is preferably in a solid phase state during normal operating conditions of the battery storage system 10 in a temperature range of -50 °C to +200 °C. The first material can be present in the emergency protection layer 40 in powder form, sintered, and / or crystallized form. Furthermore, the emergency protection layer 40 has a minimum wall thickness in the z-direction of at least 3 mm up to and including 50 mm. The emergency protection layer 40 can preferably have a substantially constant wall thickness in both the transverse and longitudinal directions over its entire extent, such that it essentially has a plate-like shape. The emergency protection layer 40 can preferably extend within the interior of the housing 56 in the x- and / or y-direction to the housing cover 50 and / or the housing shell 55 and abut the housing shell 55 and / or the housing cover 50. The emergency protection layer 40 can be formed in one piece and essentially of a single material.The emergency protection layer 40 can also be composed of several individual elements. The housing 30, together with the housing cover 50 and the housing shell 55, preferably seals the housing interior 56 fluid-tight from the environment of the vehicle 5. The housing cover 50 and / or the housing shell 55 can be made of a second material, wherein the housing 30 comprises at least one of the following second materials: aluminum, copper, or an aluminum alloy. The second material of the housing 30 can, for example, have a second melting point of less than 600 °C, in particular less than 550 °C up to and including 400 °C. This design has the advantage that the housing 30 can be made particularly lightweight and stable in order to secure the energy storage cell arrangement 35, which is often quite heavy and located in the interior of the housing 56, within the vehicle 5. Furthermore, the second materials mentioned are also suitable for housing the battery storage system 10 in a mechanically rigid and, in particular, crash-resistant manner. Fig. 3 shows a schematic sectional view along a section plane AA shown in Fig. 1 through the battery storage system 10 shown in Fig. 1 and Fig. 2 according to the first embodiment. The housing cover 50 is preferably arranged in the z-direction on the side facing the passenger compartment 75. The housing cover 50 can, for example, be manufactured using a stamping and bending process. The housing cover 50 has an outer wall 100. The outer wall 100 encloses, for example, the housing interior 56 together with the housing shell 55. The outer wall 100 is, for example, located on the side of the housing cover 50 facing the passenger compartment 75. In this embodiment, the housing cover 50 is arranged adjacent to the emergency protection layer 40. In particular, it is possible, for example, that the emergency protection layer 40 is mechanically attached to a first inner surface 90 of the housing cover 50. It is also possible, for example, that the emergency protection layer 40 is glued to the first inner surface 90. By arranging the emergency protection layer 40 on the first inner side 90 of the housing cover 50, the emergency protection layer 40 can be pre-assembled and is also protected from mechanical damage during the assembly of the housing cover 50 to the housing shell 55. To assemble the housing cover 50 together with the emergency protection layer 40, the housing cover 50 can be placed onto the housing shell 55 in a simple assembly process, so that, for example, the emergency protection layer 40 is positioned above the energy storage cell arrangement 35 and, for example, the cell contacting system 45. As explained above, electrical energy is supplied to the energy storage cell arrangement 35 during the charging process, particularly during fast charging, or the energy storage cell arrangement 35 is discharged or charged, for example, by recuperation, during driving. In these processes, the energy storage cell arrangement 35 heats up. During normal operation, the temperature of the energy storage cell arrangement 35 is between -20 °C and +80 °C. Both falling below and exceeding these temperature limits is restricted by the use of lithium-ion cells. Furthermore, the energy storage cell arrangement 35 can be temperature-controlled during normal operation by the vehicle's air conditioning system 5, so that its temperature remains within these limits. Further thermal heating or cooling outside this temperature range is undesirable. The emergency protection layer 40, through the use of the first material, provides thermal protection during normal operation, safeguarding the energy storage cell arrangement 35 from the input of further heat or from heat loss from the energy storage cell arrangement 35 towards the passenger compartment 75 shown in Fig. 2. This ensures, particularly at colder temperatures, that the energy storage cell arrangement 35 does not cool down rapidly after warming up to its operating temperature and thus preferably maintains its temperature substantially. This, in particular, ensures that the energy storage cell arrangement 35 can be fast-charged at high power during a fast-charging process. By using the emergency protection layer 40 with the first material, further thermal insulation of the energy storage cell arrangement 35, at least on the housing cover 50, is unnecessary in the first embodiment. In a first emergency scenario, for example, the vehicle 5 begins to overheat and / or catch fire at one of its components, but not in the area of ​​the battery storage system 10. This can occur, for example, due to a fire in the passenger compartment 75, or a fire in the area of ​​the drive system 15, a brake system (not shown), or at the tires. In this scenario, initial heat Q1 is introduced into the housing 30 from the outside. The housing 30, particularly at the housing cover 50, is thermally connected to the emergency protection layer 40. The housing 30, for example the housing cover 50, conducts at least some of the initial heat Q1 to the emergency protection layer 40. The emergency protection layer 40 acts as a thermal insulator for the cell contacting system 40 and the energy storage cell arrangement 35 from the housing 30, so that at least some of the initial heat Q1 is not transferred to the cell contacting system 40 and the energy storage cell arrangement 35. In this process, the emergency protection layer 40 is heated to a temperature above its initial melting point. The first material of the emergency protection layer 40 melts when its initial melting point is exceeded, absorbing the initial heat Q1. This prevents the heat required for melting, also known as latent heat, from being transferred further to the energy storage cell arrangement 35. This protects the energy storage cell arrangement 35 from thermal overload. In particular, melting the emergency protection layer 40 effectively prevents the fire from spreading to the energy storage cell arrangement 35. Furthermore, melting the emergency protection layer 40 provides rescue workers with additional time until the energy storage cell arrangement 35 is thermally overloaded by the fire taking place further outside the battery storage system 10, thus providing more time in which the rescue workers can initiate measures to prevent the fire from spreading to the battery storage system 10, in particular the energy storage cell arrangement 35. In a second emergency scenario, for example, a technical defect in the energy storage cell arrangement 35 and / or in the cell contacting system 45 can cause the energy stored in the energy storage cell arrangement 35 to lead to severe thermal overheating of the components located inside the housing 56. In particular, a thermal runaway in the area of ​​the energy storage cell arrangement 35 can be triggered. A second heat Q2 released in this process is transferred from the energy storage cell arrangement 35 to the emergency protection layer 40 and at least partially absorbed by the emergency protection layer 40. The second heat Q2 melts the emergency protection layer 40, whereby the emergency protection layer 40 acts as thermal insulation towards the housing cover 50 and the passenger compartment 75 and at least partially stores the second heat Q2 as latent heat. The occupants of vehicle 75 are thermally protected by the emergency protection layer 40, thus increasing the time interval for the occupants of vehicle 5 to exit and / or rescue the occupants. The placement of the emergency protection layer 40 on the side facing passenger compartment 75 therefore provides protection for the vehicle occupants. Furthermore, at least in the second emergency scenario, the emergency protection layer 40 prevents the housing 30, and in particular the housing cover 50, from melting due to the second heat Q2 by melting above a melting temperature greater than 600 °C for a period of at least 30 minutes. This ensures that the housing 30 has sufficient strength to securely fasten the energy storage cell assembly 35, which can weigh several hundred kilograms, in the vehicle 5. It is advantageous if the emergency protection layer 40 is dimensioned such that it prevents the melting of the second material of the housing 30 for at least 30 minutes. This prevents the housing 30 from partially disintegrating or melting, which would expose parts of the energy storage cell assembly 35 and allow oxygen from the environment to penetrate to the energy storage cell assembly 35. This further prevents a fire that might occur due to thermal runaway. After one of the two emergency scenarios has ended, the molten emergency protective layer 40 cools down and solidifies. The salt-containing first material can then recrystallize into the emergency protective layer 40. The use of fluorinated salt or boron-containing salt and / or halogen-containing salt has the advantage that this salt also has a fire-extinguishing effect and thus, even if a fire occurs in the area of ​​the energy storage cell arrangement 35 in the housing interior 56, the emergency protection layer 40 also acts as a fire extinguisher. The arrangement of the emergency protection layer 40 spatially close to the cell contacting system 45 with the cell connectors of the cell contacting system 45 further has the advantage that, should the trigger for the second emergency scenario be located in the area of ​​the cell contacting system 45, the emergency protection layer 40 is spatially very close to the fire-causing component, in this embodiment in the cell contacting system 45, in order to have a cooling effect. Fig. 4 shows a sectional view along the section plane AA shown in Fig. 1 through a battery storage system 10 according to a second embodiment. The battery storage system 10 is essentially identical to the battery storage system 10 described in Figures 1, 2 to 3. The following discussion focuses exclusively on the differences between the battery storage system 10 shown in Figure 4 according to the second embodiment and the battery storage system 10 shown in Figures 1, 2 to 3 according to the first embodiment. In the second embodiment, the housing cover 50 has an outer wall 100 and an inner wall 105. The outer wall 100 is arranged on the side of the housing cover 50 facing away from the energy storage cell arrangement 35 and, together with its first inner surface 90, defines the interior of the housing 56. The inner wall 105 of the housing cover 50 is spaced apart from the first inner surface 90 of the outer wall 100 on the side facing the energy storage cell arrangement 35. The inner wall 105 divides the housing interior 56 into a layered space 110 and a celled space 115. The inner wall 105 can, for example, be bonded to the outer wall 100. Preferably, the outer wall 100 and the inner wall 105 can be manufactured separately using a stamping and bending process. The emergency protection layer 40 is arranged in the layered space 110. The emergency protection layer 40 can be segmented and arranged in individual sections within the layer chamber 110. Preferably, the layer chamber 110 is completely filled by the emergency protection layer 40. The emergency protection layer 40 can, for example, be arranged in the layer chamber 110 in block form (as already explained in Figures 1 and 2) or at least partially in powder form. The powder form has the advantage that, after joining the inner wall 105 and the outer wall 100 to form the housing cover 50, the powdered first material for forming the emergency protection layer 40 can be filled, for example blown in, into the layer chamber 110 via a filling opening (not shown in Figure 3). The inner wall 105, for example, is thermally conductive, so that the emergency protection layer 40 is thermally connected for the transfer of the second heat Q2 between the components arranged in the cell space 115, in particular the cell contacting system 45 and the energy storage cell arrangement 35. Specifically, the inner wall 105 can comprise the second material already described above. Additionally or alternatively, it is also possible that the outer wall 100 also comprises the second material described above. The arrangement of the emergency protection layer 40 in the layer space 110 has the advantage that, in the emergency scenarios mentioned above, the flow of the molten first material of the emergency protection layer 40 towards and / or into the energy storage cell arrangement 35 can be avoided. In particular, this ensures that any local hotspots occurring in the emergency protection layer 40, and the associated local islands of liquid first material, remain in the not yet completely molten emergency protection layer 40. The second embodiment shown in Fig. 4 further protects both vehicle occupants and the energy storage cell arrangement 35 from fire in both emergency scenarios. Fig. 5 shows a sectional view along the section plane AA shown in Fig. 1 through a battery storage system 10 according to a third embodiment. The battery storage system 10 is essentially identical to the battery storage system 10 described in Figures 1, 2 to 3 according to the first embodiment. The following discussion focuses exclusively on the differences between the battery storage system 10 shown in Figure 4 according to the third embodiment and the battery storage system 10 described in Figures 1 and 2. In Fig. 5, a further emergency protection layer 130 is provided in addition to the emergency protection layer 40 shown in Figs. 1, 2 to 3. The further emergency protection layer 130 is essentially identical to the emergency protection layer 40, and both emergency protection layers 40 and 130 comprise the first material. The only difference is the geometric design of the further emergency protection layer 130 compared to the emergency protection layer 40 shown in Figs. 1, 2 to 3. The additional emergency protection layer 130 is arranged in the area of ​​the housing shell 55. In particular, the additional emergency protection layer 130 preferably completely covers a second inner surface 120 of the housing shell 55 on the inside. Analogous to the fixing of the emergency protection layer 40 to the housing cover 50, the additional emergency protection layer 130 can also be mechanically attached to the second inner surface 120. The additional emergency protection layer 130 can, for example, be prefabricated and shell-shaped, so that on its outer surface the additional emergency protection layer 130 essentially has a contour of the second inner surface 120 of the housing shell 55. Thus, for example, during the manufacture of the battery storage system 10, the additional emergency protection layer 130 can be inserted into the housing shell 55. Subsequently, the energy storage cell arrangement 35 together with the cell contacting system 45 is mounted onto the additional emergency protection layer 130, which is arranged in the housing shell 55. Following this, the housing cover 50 with the emergency protection layer 40 can be mounted onto the housing shell 55. The embodiment shown in Fig. 5 has the advantage that the emergency protection layers 40, 130 essentially completely enclose the energy storage cell arrangement 35, thereby thermally isolating the energy storage cell arrangement 35 from the environment during normal operation. This eliminates the need for additional thermal insulation for the battery storage system 10. Furthermore, the additional emergency protection layer 130, which is also arranged laterally and underneath the energy storage cell arrangement 35, protects the energy storage cell arrangement 35 in both emergency scenarios analogously to the emergency protection layer 40. The embodiment shown in Fig. 5 further has the advantage that the emergency protection layers 40, 130 can absorb a particularly large amount of first and / or second heat Q1, Q2. This significantly extends the time available for rescue workers to carry out rescue measures for vehicle occupants, as well as until cooling of the battery storage system 10 can be initiated. Fig. 6 shows a schematic sectional view through a vehicle 5 with a battery storage system 10 according to a fourth embodiment. The fourth embodiment is essentially identical to the first embodiment described in Figs. 1, 2 to 3. The following discussion focuses exclusively on the differences between the fourth embodiment shown in Fig. 6 and the first embodiment of the battery storage system 10 shown in Figs. 1, 2 to 3. In this embodiment, for example, the energy storage cells 80 are partially spaced apart from one another. A gap 125 is arranged between two adjacent energy storage cells 80. The emergency protection layer 40 is arranged, for example, as shown in Figures 1 and 2, on the upper side of the energy storage cell arrangement 35. Additionally, a further portion of the emergency protection layer 40 extends into the gap 125. The emergency protection layer 40 in the gap 125 is, for example, formed as a loose fill. In particular, the emergency protection layer 40 in the gap 125 can be in powder form. Under normal operating conditions, the energy storage cell arrangement 35 heats up only within the temperature range specified above, so that the emergency protection layer 40 remains in a powdered state in the gap 125 until the first and / or second emergency scenario occurs. If necessary, the emergency protection layer 40 remains in a powdered state at least between the energy storage cells 80 until the end of the battery storage system 10's service life. It is particularly advantageous if, in the fourth embodiment shown in Fig. 6, the emergency protection layer 40 is formed entirely as a loose fill within the housing interior 56. This design has the advantage that even small gaps and / or cracks can be filled with the powdered emergency protection layer 40. When the first and / or second emergency scenario occurs and the first material of the emergency protection layer 40 is heated above its first melting temperature of 600 °C, the powdered emergency protection layer 40 melts and absorbs the first and / or second heat Q1, Q2, thus cooling the energy storage cell arrangement 35. After the molten first material of the emergency protection layer 40 cools, the emergency protection layer 40 solidifies but no longer returns to its powdered state. The powdered emergency protection layer 40 has the further advantage that it can be introduced into the housing interior 56 by means of a blowing process and tolerances can be compensated for. Furthermore, the powdered design has the additional advantage that, when the energy storage cells 80 expand or contract during normal operation, for example during charging or discharging, the powdered first material of the emergency protection layer 40 is particularly elastic and compressible, so that the emergency protection layer 40 is elastic and reversible despite its salt-containing first material and is particularly suitable to be arranged between the energy storage cell arrangement 35 and the second inner wall 105. The powdered first material can be deposited in small pores and spaces between the energy storage cells 80. It is particularly advantageous if the first material is porous. Reference symbol list 5 Vehicle 10 Battery storage system 15 Drive system 20 First high-current connection 25 Charging port 26 Second high-current connection 30 Housing 35 Energy storage cell arrangement 40 Emergency protection layer 45 Cell contacting system 50 Housing cover 55 Housing shell 56 Housing interior 60 First axle 65 Second axle 70 Drive motor 75 Passenger compartment 80 Energy storage cell 90 First inner side (of the housing cover) 100 Outer wall 105 Inner wall 110 Layer space 115 Cell space 120 Second inner side (of the housing shell) 125 Gap 130 Further emergency protection layer

Claims

Battery storage system (10) for an electric vehicle (5),- wherein the battery storage system (10) comprises a housing (30), an energy storage cell arrangement (35) with at least one electrical energy storage cell (80) and an emergency protection layer (40, 130),- wherein the housing (30) at least partially encloses a housing interior (56),- wherein the energy storage cell arrangement (35) and the emergency protection layer (40, 130) are arranged in the housing interior (56),- wherein the emergency protection layer (40, 130) is thermally coupled to the energy storage cell arrangement (35) and / or the housing (30),- wherein the emergency protection layer (40, 130) comprises a salt-containing first material with a first melting temperature greater than 600 °C,- wherein the emergency protection layer (40, 130) is designed to, in the event of a thermal emergency and heating of the emergency protection layer (40, 130) to melt to a temperature greater than 600 °C, characterized thereby,that- the housing (30) has a housing cover (50),- wherein the housing cover (50) has an inner wall (105) and an outer wall (100),- wherein the outer wall (100) at least partially delimits the housing interior (56),- wherein the inner wall (105) is arranged on the inside of the outer wall (100) and divides the housing interior (56) into a cell space (115) and a layer space (110),- wherein the energy storage cell arrangement (35) is arranged in the cell space (115),- wherein the emergency protection layer (40, 130) is arranged in the layer space (110). Battery storage system (10) according to claim 1, wherein the emergency protection layer (40, 130) comprises at least one of the following salt-containing first materials: sodium chloride (NaCl), fluorine-containing salt, boron-containing salt, halogen-containing salt. Battery storage system (10) according to one of the preceding claims,- wherein the housing (30) comprises at least one of the following second materials:- aluminium, copper, an aluminium alloy,- and / or- wherein the second material of the housing (30) has a second melting temperature of less than 600 °C, in particular less than or equal to 550 °C. Battery storage system (10) according to one of the preceding claims, comprising a cell contacting system (45) which is arranged on the energy storage cell arrangement (35) and electrically contacts at least one of the energy storage cells (80), wherein the emergency protection layer (40, 130) is arranged between the cell contacting system (45) and the housing (30). Battery storage system (10) according to one of the preceding claims,- wherein the emergency protection layer (40, 130) is block-shaped or shell-shaped,- and / or- wherein the emergency protection layer (40, 130) comprises at least sectionally the first material in powder form. Battery storage system (10) according to one of the preceding claims,- wherein the energy storage cell arrangement (35) comprises several energy storage cells (80) which are spaced apart from each other,- wherein a gap (125) is arranged between two nearest energy storage cells (80),- wherein the emergency protection layer (40, 130) is arranged in the gap (125). Use of a battery storage system (10) in emergency operation, - wherein a battery storage system (10) is provided, - wherein the battery storage system (10) comprises a housing (30), an energy storage cell arrangement (35) with at least one electrical energy storage cell (80), and an emergency protection layer (40, 130), - wherein the housing (30) at least partially encloses a housing interior (56), - wherein the energy storage cell arrangement (35) and the emergency protection layer (40, 130) are arranged in the housing interior (56), - wherein the emergency protection layer (40, 130) is thermally coupled to the energy storage cell arrangement (35) and / or the housing (30), - wherein the emergency protection layer (40, 130) comprises a salt-containing first material with a first melting temperature greater than 600 °C, - wherein the energy storage cell arrangement (35) heats up in an emergency and the emergency protection layer (40, 130) heated to a temperature greater than 600 °C,- wherein the emergency protection layer (40, 130) absorbs the heat at least partially and stores it by melting, - wherein the emergency protection layer (40, 130) is heated at least in certain areas to a temperature greater than 600 °C, - wherein the emergency protection layer (40, 130) protects the energy storage cell arrangement (35), characterized in that - powdered particles of the first material of the emergency protection layer (40, 130) are melted, - wherein when the emergency protection layer (40, 130) cools below the first melting temperature, the powdered particles are bonded together. Use of the battery storage system (10) in emergency operation according to claim 7, - wherein heat is introduced into the housing interior (56) via the housing (30), - wherein the heat introduced into the housing interior (56) via the housing (30) heats the emergency protection layer (40, 130) to a temperature greater than 600 °C, - wherein the emergency protection layer (40, 130) protects the energy storage cell arrangement (35) from the heat at least temporarily. Use of the battery storage system (10) in emergency operation according to claim 7 or 8, wherein the energy storage cell arrangement (35) heats up in an emergency and the emergency protection layer (40, 130) heats up to a temperature greater than 600 °C, wherein the emergency protection layer (40, 130) absorbs the heat at least partially and stores it by melting, wherein the emergency protection layer (40, 130) protects the housing (30) from the heat of the energy storage cell arrangement (35) at least temporarily.

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