Battery device

Abstract

The present invention relates to a battery device. The battery device has a housing, a core structure (10) in the housing, a first interior space (14) in the housing designed for a cooling fluid (22) to flow therethrough, a second interior space (16) in the housing, a phase change material (24), and at least one battery cell (18). The core structure (12) separates the first interior space (14) from the second interior space (16). The core structure (10) has a wall (12) which is substantially in the form of a triply periodic minimal surface. The phase change material (24) is located in the second interior space (16). The at least one battery cell (18) is located in the first interior space (14) or the second interior space (16).

Description

[0001] Battery device

[0002] Technical area

[0003] The present invention relates to a battery device.

[0004] State of the art

[0005] Batteries must deliver high currents for modern applications, such as energy storage in electric cars or drones. This can, however, lead to very rapid heating of the individual battery cells. Batteries have an optimal operating temperature range, which is, for example, close to room temperature. Within this temperature range, the battery can perform particularly well. However, at temperatures that are too high or too low, battery degradation accelerates. If a maximum temperature is exceeded, the battery may even self-ignite, a process also known as thermal runaway. Accordingly, the temperature is typically controlled by a temperature control system.

[0006] Battery temperature control systems can be divided into two operating principles. Active cooling can adjust the battery's operating temperature, for example, by adjusting the flow of cooling fluid. However, active cooling requires energy, which can reduce system efficiency. Furthermore, cooling or heating of the battery by the ambient environment cannot be prevented during idle periods. Passive cooling does not consume energy, but the operating temperature cannot always be maintained within a desired range. Overall, battery cooling can require additional installation space and can be very heavy. Depending on the climate zone, battery heating may also be provided. Heating can also be active or passive.

[0007] US 2013 / 00844871 A1 describes a battery with phase change material.

[0008] US Patent No. 7,866,377 B2 describes the use of minimal surfaces in heat exchangers. Description of the invention

[0009] A first aspect of the invention relates to a battery device. The battery device can be designed, for example, for a motor vehicle, such as an electric car. The battery device can be designed as a battery storage device in a building, in particular used in a wall box for charging electric cars. The battery device can also be used, for example, in a drone or an electric motorcycle. The battery device can be designed as an energy storage device for electrical energy. The battery device can be designed for multiple charging and discharging.

[0010] The battery device may have a housing. The housing may define a housing interior. The housing may be made of plastic or metal, for example. The housing may have multiple wall elements or may be formed in one piece. The housing may protect other elements of the battery device from environmental influences and, for example, enable attachment, particularly in a vehicle and / or to a building. The battery device may have electrical contacts.

[0011] The battery device has a core structure arranged in the housing. The core structure can be designed to divide the housing interior into at least two sub-chambers. The core structure can provide an additional protective function to protect battery cells from mechanical impacts. The core structure can form a supporting structure. The core structure can, for example, be permanently connected to the housing or formed as a single piece. Through the connection to the housing, the core structure can support the housing and thus further reinforce it.

[0012] The battery device has a first interior space in the housing. The first interior space is designed for a cooling fluid to flow through. For this purpose, the first interior space can have one or more access openings, in particular designed as through-openings in the housing. This allows a cooling fluid to flow through the first interior space. The battery device can, for example, have a pumping device for conveying the cooling fluid through the first interior space, which can be arranged inside or outside the housing. In addition, a heat exchanger can be provided, in particular outside the housing, for example to cool the cooling fluid. Alternatively or additionally, the battery device can have a heater, for example to heat the cooling fluid.The battery device can thus have active temperature control, in particular at least one configured for cooling, in order to reliably maintain an operating temperature within a desired range. Alternatively or additionally, the battery device can also be heated by means of the cooling fluid, depending on the ambient temperature. The cooling fluid can be, for example, air, water, or a water-glycol mixture.

[0013] The battery device has a second interior space in the housing. The second interior space can, for example, be fluidically separated from the first interior space. The battery device has a phase-change material. The phase-change material is arranged in the second interior space. This prevents mixing with the cooling fluid. A phase-change material can have a high enthalpy of fusion. The phase-change material can be, for example, a paraffin wax. Another example of a phase-change material is an aluminum-silicon alloy. Further examples of phase-change materials include salt hydrates, alcohols, fatty acids, and salts. In addition, a flame-retardant additive can be added to the phase-change material.The phase-change material can be selected such that it changes between two phases, in particular a liquid and a solid state, in or close to the desired operating temperature range of the battery device. The phase-change material can have a high effective thermal mass, which greatly increases the thermal inertia of the battery device. This can prevent or at least slow down an undesirably rapid and / or high temperature rise or drop. This makes it easier to maintain the desired operating temperature of the battery device. In addition, the active cooling system can be smaller, as it no longer has to absorb the respective thermal reactions of the battery alone. The phase-change material can dampen load peaks to relieve the load on the active cooling and / or heating system.In addition, the phase-change material can maintain the temperature of the battery device better, or with less mass and volume, even during idle times—for example, when the battery device is switched off—than would be possible without the phase-change material. This can extend the battery device's service life. The phase-change material allows the battery device to be particularly lightweight, as the active cooling components can be smaller. Furthermore, system efficiency with such a battery device can be greater, as less energy is required for active cooling. Since the battery device can be better maintained within its optimal operating temperature range, the battery device's service life can also be particularly long.

[0014] The battery device has at least one battery cell. The battery cell can be designed, for example, as a galvanic cell. The battery cell can be an electrochemical energy store and an energy converter. The battery cell can be, for example, a cylindrical battery cell, a prismatic battery cell, or a pouch cell. The battery device can have a plurality of battery cells, which can be arranged in a specific package in the housing. For example, the battery cells can be arranged uniformly at specific distances from one another in a plane. All battery cells of the battery device can be designed identically. However, the battery device can also have two or more different battery cell types. For the sake of simplicity, the term "battery cell" will be used below, although this can always refer to several or all of the battery cells, where applicable.

[0015] The core structure separates the first interior space from the second interior space. The core structure can form a partition wall in the housing interior. The separation can be fluid-tight, in particular for the phase change material and the cooling fluid. The core structure has a wall which is essentially in the shape of a triply periodic minimal surface. The partition wall can partially or completely delimit at least one of the two interior spaces. The partition wall can also at least partially or completely delimit both interior spaces. The triply periodic minimal surface can have a symmetry of a crystal structure. The triply periodic minimal surface can be free of interfaces. Details of the triply periodic minimal surface will be explained further below. The triply periodic minimal surface can form a particularly large surface area, so that heat can be transferred particularly well and evenly between the two interior spaces.The triply periodic minimal surface can form a dedicated recess for each battery cell, for example, in the second interior space. The wall of the core structure can be made of a metallic material or plastic, for example. The triply periodic minimal surface can form two channels in conjunction with the housing. Heat can be transferred particularly effectively between the cooling fluid and the phase-change material via the triply periodic minimal surface. The combination of active cooling and thermal damping by the phase-change material can thus be particularly efficient. The phase-change material can also prevent thermal runaway particularly effectively.

[0016] The at least one battery cell is arranged in the first interior space or the second interior space. Due to the arrangement in the second interior space, undesirably rapid heating and cooling of the battery cell can be dampened particularly effectively by the phase-change material. Thus, each battery cell can be kept within a desired operating temperature range with particularly low active temperature control. Due to the arrangement in the first interior space, the operating temperature of the battery cell can be adjusted particularly precisely and reliably. Nevertheless, the phase-change material can dampen thermal load peaks.

[0017] In one embodiment of the battery device, it is provided that the first interior space and / or the second interior space is delimited on one side by a cover layer. This cover layer can, for example, be formed by part of the housing. On an opposite side, the first interior space and / or the second interior space can be delimited by a further cover layer. This further cover layer can, for example, also be formed by part of the housing. The cover layers can be connected to the core structure. Each cover layer can be non-electrically conductive. Each cover layer can, for example, be formed as a plate made of an electrically insulating material. Each cover layer can, for example, also be formed from a composite material and thus be particularly mechanically resistant. The cover layers can adjoin the core structure in some regions and / or form a sandwich structure with the core structure.This means that the battery device can be designed as a load-bearing structure. This means, for example, that reinforcements are not required in a vehicle when installing this battery device. The battery device can thus be designed, for example, as a load-bearing part of a body. The cover layers can, for example, rest on opposite sides of the wall designed as a triply periodic minimal surface and thus delimit or completely close the respective recesses for battery cells on the top and bottom. The cover layers can, for example, be connected to the core structure by a joining process such as welding, gluing, or soldering. The two cover layers can, however, also be connected to one another, for example by screwing, and the core structure can be clamped between them. The two cover layers can also be pressed against the core structure by the housing.

[0018] In one embodiment of the battery device, it is provided that at least one of the cover layers has at least one through-opening for access to a battery contact of the battery cell and / or for the flow of the cooling fluid. Separate through-openings can also be provided for the cooling fluid flow and the electrical contact. The through-opening can, for example, be aligned with the recess for the battery cell. An associated through-opening can be provided for each battery cell. The through-openings can be provided in only one or both cover layers. One or more lines, for example power lines and / or fluid lines, can be routed through the through-opening. The through-opening can otherwise be sealed. This allows fluid and / or electrical current to be guided into and out of the first interior space and / or second interior space.

[0019] In one embodiment of the battery device, it is provided that at least one of the cover layers has a conductor track that is in contact with the battery cell, in particular wherein the conductor track is arranged on an outer side of the cover layer. For example, the conductor track can be connected to the battery cell through the through-opening. An associated conductor track can be provided for each battery cell. However, the conductor track can also be electrically connected to one or more battery cells, for example. The conductor track can be attached to the cover layer. The conductor track can also be formed integrally with the cover layer, for example by etching into or depositing onto the cover layer. The conductor track can provide an electrical connection to the respective battery cells in a compact, robust, and space-saving manner.

[0020] In one embodiment of the battery device, it is provided that the core structure was manufactured using an additive process. For example, the core structure can be produced using a metallic 3D print. This makes it particularly easy to manufacture the complex wall in the form of a triply periodic minimal surface, in particular in one step and / or as a one-piece element. For example, even strong undercuts can be easily manufactured in this way. Alternatively or additionally, the core structure can be manufactured using a primary forming process. For example, two semi-finished products manufactured in a casting process can form the core structure. This allows particularly solid core structures to be manufactured cost-effectively. Alternatively or additionally, the core structure can be manufactured using a machining process. For example, two semi-finished products manufactured in a milling process can form the core structure.This allows for a particularly resilient core structure. Alternatively or additionally, the core structure can be manufactured using a forming process. For example, two semi-finished products made from sheet metal in a deep-drawing process can form the core structure. This enables particularly cost-effective mass production.

[0021] In one embodiment of the battery device, it is provided that the core structure is formed from two semi-finished products joined together. For example, the core structure can be formed from an upper shell and a lower shell, which form respective recesses for the battery cells between them. Production can thus be particularly simple, in particular since undercuts in the semi-finished products can be avoided. In addition, the battery cells can be inserted into the recesses particularly easily. The semi-finished products can be symmetrical to one another. For example, the core structure can also comprise three or more semi-finished products joined together. The semi-finished products can be connected to one another, for example, by a joining method such as welding, gluing, or soldering. In one embodiment of the battery device, it is provided that the core structure further comprises a first lattice structure which is arranged in the first interior space.The first grid structure can increase the load-bearing capacity of the battery device. For example, the first grid structure can support the core structure on the housing and / or the cover layers and connect them to one another. Furthermore, the first grid structure can increase thermal conductivity, in particular by enlarging the surface area around which the cooling fluid flows. Preferably, the first grid structure is a coarse grid structure with a large spacing between individual grid bars in order to minimize pressure loss when the cooling fluid flows through the first interior space.

[0022] In one embodiment of the battery device, it is provided that the core structure further comprises a second lattice structure which is arranged in the second interior space. The second lattice structure can be provided alternatively or in addition to the first lattice structure. The second lattice structure can increase a load-bearing capacity of the battery device. For example, the second lattice structure can support the core structure on the housing and / or the cover layers and connect them to one another. The second lattice structure can also increase a mechanical resistance of the core structure itself, for example by various wall regions in the recesses for the battery cells being connected to one another via the second lattice structure. The second lattice structure can, for example, also hold the battery cells, in particular when the phase change material changes to its liquid state.In addition, the second lattice structure can increase thermal conductivity, particularly by enlarging the surface area contacted by the phase-change material. Preferably, the second lattice structure is a fine lattice structure with small spacing between individual lattice bars to provide a particularly large surface area for heat transfer.

[0023] The first lattice structure can differ from the second lattice structure. For example, the second lattice structure can be finer than the first lattice structure. Alternatively or additionally, respective lattice bars of the first lattice structure can have a different thickness than the respective lattice bars of the second lattice structure. A lattice structure can, for example, be formed from a plurality of intersecting lattice bars. In one embodiment of the battery device, it is provided that the core structure is double-walled with a further wall. The further wall can also be formed essentially in the form of a triply periodic minimal surface. In a double-walled core structure, the two walls can be arranged essentially parallel to one another. For example, the basic shape of both walls can be the same. The two walls can be offset from one another.One of the two walls can be smaller and, for example, be arranged between the other wall and the second interior space. An intermediate space can be formed between the two walls of the core structure. The double-walled core structure can be particularly robust. Additional phase change material can be arranged in the additional intermediate space. This phase change material can have a different melting point than the phase change material in the second interior space in order to further stabilize the operating temperature. For example, one of the phase change materials can melt at an upper limit of a desired operating temperature range and the other phase change material at a desired lower limit of the desired operating temperature range. Alternatively, the intermediate space can be designed for a cooling fluid to flow through.This allows for particularly variable active cooling, for example, by using different cooling fluids in the intermediate space and the first interior space. For example, a constant cooling fluid volume flow can be applied to the first interior space, while cooling fluid can only be applied to the intermediate space once the phase-change material begins to melt.

[0024] In one embodiment of the battery device, it is provided that the intermediate space is designed for a cooling fluid to flow through and / or a phase change material is arranged in the intermediate space.

[0025] In one embodiment of the battery device, it is provided that the core structure further comprises a third lattice structure arranged in the intermediate space. The third lattice structure can fasten and support the two walls of the double-walled core structure to one another. The two walls of the core structure can be connected to one another via the third lattice structure. This makes the core structure particularly robust and able to absorb high mechanical loads. Alternatively, the two walls can also be arranged side by side in a self-supporting manner, for example. The third lattice structure can improve heat transfer between the two walls of the core structure and to a material in the intermediate space.

[0026] In one embodiment of the battery device, it is provided that respective walls of the core structure are designed as a black P surface. The black P surface naturally forms a geometry that spans two separate spaces and creates recesses for cylindrical batteries. A black P surface can be approximated, for example, in a three-dimensional Cartesian coordinate system with the coordinates x, y, and z using the equation cos(x) + cos(y) + cos(z) = 0. By inserting further parameters, the geometry can be compressed or stretched to adapt it to differently shaped batteries. The equation used for this approximation is cos(a * x) + cos(ö * y) + cos(c * z) = 0. The black P surface can also be precisely determined by solving the Weierstrass-Enneper formula.

[0027] In one embodiment of the battery device, it is provided that the respective walls of the core structure are adapted to the battery cell shape. For example, the respective walls of the core structure can have a hexagonal symmetry. This allows a suitable shape with matching recesses to be provided for specific battery cells.

[0028] A further aspect relates to a method for determining a shape of a wall of a core structure of a battery device, in particular one of the walls of the core structure of the battery device according to the invention. The method may comprise a step of selecting a battery cell shape of respective battery cells of the battery device. The method may comprise a step of specifying an arrangement of the battery cells in a desired package, in particular in a plane. The method may comprise a step of identifying planes of symmetry in the specified arrangement of the battery cells. The method may comprise a step of reducing battery cell surfaces in the specified arrangement to a smallest symmetrical unit. The method may comprise a step of selecting contact surfaces of the battery cells with the wall.The method may include a step of defining contact lines on the selected contact surfaces. The method may include a step of defining the spatial position of the contact lines. The method may include a step of determining the shape of the wall as a substantially triply periodic minimal surface depending on the defined spatial position of the contact lines and depending on the identified symmetry planes. As a result, battery device-specific triply periodic minimal surfaces can be easily determined. The step of determining the shape of the wall as a substantially triply periodic minimal surface may include converting the attachment surface formed from the defined contact lines into a mesh of prestressed spring elements and mass points in order to determine a spring-mass system.The step of determining the shape of the wall as a substantially triply periodic minimal surface may comprise a dynamic simulation of the spring-mass system until an equilibrium position is reached. For example, an explicit finite element method solver such as ABAQUS / explicit is suitable for this purpose. The step of determining the shape of the wall as a substantially triply periodic minimal surface may comprise converting the equilibrium position into a geometric surface to determine a minimal surface. The step of determining the shape of the wall as a substantially triply periodic minimal surface may comprise mirroring the geometric surface across all identified symmetry planes to create a cell of the triply periodic minimal surface.The step of determining the shape of the wall as a substantially triply periodic minimal surface may comprise periodically piecing the created cell according to the arrangement of the battery cells in the desired package to determine the shape of the wall of the core structure.

[0029] In one embodiment of the battery device, it is provided that the shape of the respective walls of the core structure, which in particular separate the two interior spaces from one another, is matched to a shape of the battery cell. This allows the battery device to be particularly compact. For example, respective recesses in the second interior space can be adapted to the shape of the battery cells. In particular, a cross-section of the recess can correspond to a cross-section of the battery cell. For example, the shape of the wall of the core structure can be matched to a cylindrical shape or a prismatic shape of the battery cell, or to a battery cell designed as a pouch cell.

[0030] In one embodiment of the battery device, it is provided that the battery device has a pumping device designed to convey the cooling fluid through the first interior space. For example, the pumping device can be connected to the first interior space via one or more through-openings in at least one cover layer. The pumping device can also be designed to convey cooling fluid through the intermediate space if the core structure has a double-walled design. The pumping device can, for example, comprise a pump. The battery device can also comprise the cooling fluid.

[0031] Short description of the characters

[0032] Fig. 1 illustrates in a schematic perspective view a first embodiment of a core structure of a battery device.

[0033] Fig. 2 illustrates in a schematic perspective view how the first embodiment of the core structure of the battery device can be surrounded by a cooling fluid.

[0034] Fig. 3 illustrates in a schematic sectional view how the first embodiment of the core structure of the battery device accommodates respective battery cells and a phase change material.

[0035] Fig. 4 illustrates in a further schematic sectional view how the first embodiment of the core structure of the battery device accommodates respective battery cells and a phase change material.

[0036] Fig. 5 illustrates, in a schematic perspective view, how the first embodiment of the core structure can be manufactured using a deep-drawing process. Fig. 6 illustrates, in a schematic perspective view, a second embodiment of a core structure of the battery device, which has additional grid structures.

[0037] Fig. 7 illustrates in a schematic sectional view the lattice structures of the second embodiment of the core structure of the battery device.

[0038] Fig. 8 illustrates in a schematic perspective view a third embodiment of a core structure of the battery device, which is double-walled.

[0039] Fig. 9 illustrates in a schematic sectional view a space formed by the double-walled core structure.

[0040] Fig. 10 schematically illustrates a method for determining a shape of a triply periodic minimal surface for the core structure.

[0041] Fig. 11 illustrates in different views a shape of the core structure with hexagonal symmetry determined by the method according to Fig. 10.

[0042] Detailed description of embodiments

[0043] Fig. 1 illustrates a schematic perspective view of a first embodiment of a core structure 10 of a battery device. The core structure 10 has a wall 12 formed in the form of a triply periodic minimal surface. In the example shown, the wall 12 of the core structure 10 is formed as a black P surface.

[0044] The battery device has a housing (not shown), which here is rectangular, for example, and completely accommodates the core structure 10. The core structure 10 borders the housing in certain areas on the outside and is held by it. On the top and bottom sides, the housing forms a cover layer, which borders the wall 12 and is joined to the wall 12 of the core structure 10. This forms a robust sandwich structure with the core structure. A housing interior is separated by the core structure 10 into a first interior space 14 and a second interior space 16, such that no fluid transfer between the two interior spaces 14, 16 is possible.

[0045] The battery device has a plurality of battery cells 18 arranged evenly in a pack, which in the example shown are designed as cylindrical battery cells 18 and are shown in Fig. 2 to Fig. 4. In Fig. 2 to Fig. 4 it can be seen that the core structure 10 forms individual recesses 20 in the second interior space 16, which correspond to a shape of the battery cells 18. An associated battery cell 18 is arranged in each recess 20. In the example shown, the battery device has only one level of battery cells 18. However, the battery device can also have several levels of battery cells 18 arranged one above the other and thus be extended in the vertical direction. For this purpose, several core structures 10 can be stacked one above the other or the core structure 10 can be extended in the vertical direction, with additional recesses 20 being formed for the further battery cell levels.

[0046] The first interior space 14 is designed to have a cooling fluid 22 flowing through it. In Fig. 2 to Fig. 4 it can be seen that the first interior space 14 is completely filled with cooling fluid 22. The cooling fluid 22 is, for example, a water-glycol mixture. The battery device has a pump device which is connected to the first interior space 14 via an inlet and an outlet in order to convey the cooling fluid 22 through the first interior space 14. This allows a temperature of the battery device to be actively controlled, for example for cooling and heating. The top and / or bottom of the battery cells 18 are not in contact with the cooling fluid 22. There, the battery cells 18 are electrically connected in order to be able to supply an electrical current to a consumer and to be charged.

[0047] For this purpose, the cover layers each have associated through-openings aligned with the battery cells 18 and the recesses 20. The cover layers are formed, for example, from an electrically insulating material in a sandwich construction, with respective conductor tracks deposited or etched on a side facing away from the first interior space 14.

[0048] The second interior space 16 fluidically connects the recesses 20 to one another. A phase-change material 24, for example, paraffin wax, is arranged in the second interior space 16 and surrounds the battery cells 18. The phase-change material 24 forms a thermal buffer and significantly increases the thermal inertia of the battery device within the desired operating temperature range. The core structure 10 is formed, for example, from a metallic material to enable rapid heat transfer between the first interior space 14 and the second interior space 16, and thus between the cooling fluid 22 and the phase-change material 24.

[0049] In another embodiment, the phase change material 24 is arranged in the first interior space 14 and the cooling fluid 22 in the second interior space 16. In this case, the pumping device is connected to the second interior space 16 via an inlet and an outlet in order to convey the cooling fluid 22 therethrough.

[0050] The core structure 10 can, for example, be manufactured using an additive process, whereby the complex geometry of the core structure 10 can be created particularly easily. Fig. 5 illustrates, in various schematic views, a forming process for manufacturing the core structure 10. Shown is a deep-drawing tool 30 which forms a negative mold of a part of the wall 12. A sheet metal plate 32 which has through openings 34 corresponding to the recesses 20 is placed on the deep-drawing tool 30. By pressing with a further deep-drawing tool (not shown), a semi-finished product 36 is formed from the sheet metal plate 32, the shape of which corresponds to an upper or lower half of the core structure 10. Two such semi-finished products 36 are joined together, for example by gluing, soldering, or welding, to form the wall 12 of the core structure 10, as shown in Fig. 5. This enables cost-effective mass production.

[0051] One shape of the cover layer corresponds, for example, to the shape of the sheet metal plate 32 shown in Fig. 5, from which the semi-finished products 36 are deep-drawn. Fig. 6 illustrates a second embodiment of the core structure 10 of the battery device in a schematic perspective view, and Fig. 7 illustrates a schematic sectional view. Only differences from the first embodiment will be described, since the basic structure and basic mode of operation are identical to the first embodiment.

[0052] The second embodiment of the core structure 10 has a first grid structure 50 arranged in the first interior space 14. The first grid structure 50 is formed from uniformly arranged metallic grid bars 52 that intersect and are connected to the wall 12. Additionally, the grid bars can also be connected to the housing, particularly the cover layers, to structurally reinforce the housing. The first grid structure 50 improves heat transfer between the wall 12 and the cooling fluid 22 by increasing the contact surface.

[0053] The second embodiment of the core structure 10 has a second lattice structure 54, which is arranged in the second interior space 16. The second lattice structure 54 is formed from uniformly arranged metallic lattice bars 56 that intersect and are connected to the wall 12. The second lattice structure 54 can thus stiffen the wall 12. The second lattice structure 54 improves heat transfer between the wall 12 and the phase change material 24 and the battery cells 18 because a contact surface is increased. The lattice bars 56 of the second lattice structure 54 can be in contact with the battery cells 18 in order to provide additional support when the phase change material 24 changes to the liquid state. However, the lattice bars 56 of the second lattice structure 54 can also be spaced apart from the battery cells 18.

[0054] The first lattice structure 50 has larger spacings between its lattice bars 52 than the second lattice structure 54 between its lattice bars 56. The first lattice structure 50 is coarser than the second lattice structure 54. The coarse first lattice structure 50 can prevent an undesirably high flow resistance for the cooling fluid 22 in the first interior space 14. The fine second lattice structure 54 can achieve particularly good heat transfer between the phase change material 24 and other regions, thereby enabling particularly good thermal damping. Fig. 8 illustrates a schematic perspective view and Fig. 9 a schematic sectional view of a third embodiment of the core structure 10 of the battery device. Only differences from the first embodiment will be described, since the basic structure and basic mode of operation are identical to the first embodiment.

[0055] The core structure 10 according to the third embodiment is double-walled with an additional wall 70. The additional wall 70 is arranged parallel to the wall 12 and also has the shape of a three-fold periodic minimal surface, in the example shown as a black P surface. The core structure forms a gap 74 between the two walls 12, 70. The two walls 12, 70 are each connected to the cover layers and thus do not need to be fastened to one another. In the example shown, however, the two walls 12, 70 are connected to one another by means of an optional third lattice structure 76 arranged in the gap 74, which has respective lattice bars 78. The third lattice structure 76 improves heat transfer between the two walls 12, 70 and to a material arranged in the gap 74. In addition, the third lattice structure 76 can make the core structure 10 more robust against mechanical loads.

[0056] The core structure 10 according to the third embodiment can be free of the first lattice structure 50 and the second lattice structure 54, as shown in Fig. 9. In another embodiment, however, the first lattice structure 50 and / or the second lattice structure 54 can also be provided in addition to the third lattice structure 76. The intermediate space 70 can be designed for the flow of a cooling fluid and, for this purpose, can be fluidly connected to the pumping device. Alternatively, a phase-change material can be arranged in the intermediate space 70.

[0057] Fig. 10 schematically illustrates a method for determining a shape of a triply periodic minimal surface for the core structure 10. In step 100, one of the battery cells 18 of the battery device corresponding to a battery cell shape is selected. Shown is a cross-section of typical battery cell shapes, namely cylindrical battery cells, prismatic battery cells, and pouch cells. In step 102, an arrangement of the battery cells 18 in a desired package in a plane is determined. The cylindrical battery cells 18 are arranged evenly around one another, for example, in concentric circles. The prismatic battery cells 18 are arranged evenly in rows, for example. In step 104, planes of symmetry 106 are identified in the determined arrangement of the battery cells 18.In step 110, the battery cell surfaces in the defined arrangement are reduced to a smallest symmetrical unit, which is illustrated by box 108. In step 112, contact surfaces of the battery cells 18 with the wall 12 of the core structure 10 are selected in the smallest symmetrical unit 108. Contact lines are defined on the selected contact surfaces. The spatial position of the contact lines is then defined. Depending on the defined spatial position of the contact lines and the identified symmetry planes, the shape of the wall 10 is determined as an essentially three-fold periodic minimal surface.The step of determining the shape of the wall as a substantially triply periodic minimal surface may comprise converting the attachment surface formed from the defined contact lines into a mesh of prestressed spring elements and mass points in order to determine a spring-mass system. The step of determining the shape of the wall as a substantially triply periodic minimal surface may comprise dynamically simulating the spring-mass system until an equilibrium position is reached. This allows battery device-specific triply periodic minimal surfaces to be easily determined. The step of determining the shape of the wall as a substantially triply periodic minimal surface may comprise converting the equilibrium position into a geometric surface in order to determine a minimal surface.The step of determining the shape of the wall as a substantially triply periodic minimal surface can comprise mirroring the geometric surface across all identified symmetry planes to create a cell of the triply periodic minimal surface. The step of determining the shape of the wall as a substantially triply periodic minimal surface can comprise periodically assembling the created cell according to the arrangement of the battery cells in the desired package to determine the shape of the wall of the core structure. Fig. 11 shows a perspective view of a result of this method illustrated in Fig. 10. The core structure 10 has a wall 12 with hexagonal symmetry. Fig. 11 also shows at the top a single cell of the wall 12, which was determined according to the previously described method. This cell is periodically assembled to create the triply periodic minimal surface shape of the wall 12 from the cell.

[0058] Reference symbol

[0059] 10 Core structure

[0060] 12 Wall

[0061] 14 first interior

[0062] 16 second interior

[0063] 18 battery cells

[0064] 20 recesses

[0065] 22 Cooling fluid

[0066] 24 Phase change material

[0067] 30 deep drawing tools

[0068] 32 sheet metal plate

[0069] 34 through openings

[0070] 36 semi-finished products

[0071] 50 first lattice structure

[0072] 52 bars of the first lattice structure

[0073] 54 second lattice structure

[0074] 56 bars of the second lattice structure

[0075] 70 more walls

[0076] 74 space

[0077] 76 third lattice structure

[0078] 78 bars of the third lattice structure

[0079] 100 Step / Selecting a battery cell shape

[0080] 102 Step / Determining an arrangement of the battery cells

[0081] 104 Step / Identification of symmetry planes

[0082] 106 plane of symmetry

[0083] 108 boxes / smallest symmetrical unit

[0084] 110 Step / Reduction of battery cell surfaces

[0085] 112 Step / Selection of touch surfaces

Claims

Claims: Battery device, in particular for a motor vehicle or a battery storage system in a building, wherein the battery device comprises a housing, a core structure (10) arranged in the housing, a first interior space (14) in the housing designed for flow with a cooling fluid (22), a second interior space (16) in the housing, a phase change material (24) and at least one battery cell (18), wherein the core structure (10) separates the first interior space (14) from the second interior space (16), wherein the core structure (10) has a wall (12) which is essentially designed in the form of a triple periodic minimal surface, wherein the phase change material (24) is arranged in the second interior space (16) and wherein the at least one battery cell (18) is arranged in the first interior space (14) or the second interior space (16).Battery device according to claim 1, wherein the first interior space (14) and / or the second interior space (16) is bounded on one side by a cover layer and on an opposite side by a further cover layer, in particular wherein the cover layers adjoin the core structure (10) in certain areas and / or form a sandwich structure with the core structure (10). Battery device according to claim 2, wherein at least one of the cover layers has at least one through-opening for access to a battery contact of the battery cell (18) and / or for flow of the cooling fluid (22) and / or. wherein at least one of the cover layers has a conductor track which is contacted with the battery cell (18), in particular wherein the conductor track is arranged on an outer side of the cover layer. Battery device according to one of the preceding claims, wherein the core structure (10) was manufactured by an additive process, a forming process, a machining process and / or a forming process, in particular wherein the core structure (10) is formed from two semi-finished products (36) joined together. Battery device according to one of the preceding claims, wherein the core structure (10) further comprises a first lattice structure (50) which is arranged in the first interior space (14) and / or wherein the core structure (10) further comprises a second lattice structure (54) which is arranged in the second interior space (16), in particular wherein the first lattice structure (50) differs from the second lattice structure (54).Battery device according to one of the preceding claims, wherein the core structure (10) is double-walled with a further wall (70), wherein the further wall (70) is also substantially in the form of a triple periodic minimal surface, and an intermediate space (74) is formed between the two walls (12, 70) of the core structure (10). Battery device according to claim 6, wherein the intermediate space (74) is configured for the flow of a cooling fluid and / or a phase-change material is arranged in the intermediate space (74), and / or wherein the core structure (10) further comprises a third lattice structure (76) which is arranged in the intermediate space (74). In particular, wherein the two walls (12, 70) of the core structure (10) are connected to each other via the third lattice structure (76). Battery device according to one of the preceding claims, wherein respective walls (12, 70) of the core structure (10) are configured as Schwarz P-surfaces or wherein respective walls (12) of the core structure (10) have hexagonal symmetry. Battery device according to one of the preceding claims, wherein the shape of the respective walls (12, 70) of the core structure (10) is adapted to a shape of the battery cell (18), in particular to a cylindrical shape or a prismatic shape of the battery cell or to a battery cell (18) configured as a pouch cell. Battery device according to one of the preceding claims, wherein the battery device has a pump device configured to pump the cooling fluid (22) through the first interior space (14).

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