Energy storage device for a motor vehicle and motor vehicle, comprising an electric machine and an energy storage device connected to the electric machine

Abstract

Energy storage device for a motor vehicle (1), comprising an energy storage housing (6) and at least one battery cell (5) accommodated therein, wherein at least one cooling device (7) is arranged adjacent to the battery cell (5) or to at least one of the battery cells (5) in such a way that this battery cell (5) can be cooled by means of a cooling fluid guided in at least one cooling fluid guide section (17) of the cooling device (7), wherein at least one section of the cooling device (7) is plastically or elastically deformable, so that an expansion of the adjacent battery cell (5) or of the adjacent battery cells (5) due to a charging cycle and / or aging causes a deformation of the cooling device (7) in such a way that the cross section of the cooling fluid guide section (17) is reduced at least in sections.

Description

[0001] The present invention relates to an energy storage device for a motor vehicle, comprising an energy storage housing and at least one battery cell accommodated therein, wherein at least one cooling device is arranged adjacent to the battery cell or to at least one of the battery cells in such a way that this battery cell can be cooled by means of a cooling fluid guided in at least one cooling fluid guide section of the cooling device.

[0002] Electric vehicles, also known as electric vehicles, are becoming increasingly important. In electric vehicles, traction torque is generated by an electric machine or motor. If traction torque is generated exclusively by the electric machine, it is referred to as a pure electric vehicle. If traction torque is also generated by an internal combustion engine, it is referred to as a hybrid vehicle.

[0003] Electric vehicles present a number of technological challenges, particularly regarding the necessary on-board storage of electrical energy. For this purpose, electric vehicles feature a rechargeable electrical energy storage device, often referred to as an accumulator. The energy storage device comprises at least one battery cell containing an electrochemically active material. The energy storage device is connected to the electric motor, providing it with energy to generate traction torque. Energy storage devices with the largest possible storage capacity are desirable to achieve a long range for the motor vehicle.

[0004] One problem associated with energy storage devices and their battery cells is the fact that they heat up during operation, particularly during charging or when transferring energy to the electric machine. However, the temperature of the battery cells should not exceed certain limits to ensure the longest possible service life. In the worst case, if the energy storage device heats up too much, it could catch fire or become damaged, which could lead to the release of substances that are harmful to health and / or the environment. It is therefore extremely important to cool energy storage devices and battery cells in motor vehicles. In addition to indirect cooling, which can be achieved using airflow, for example, direct cooling is often provided. With direct cooling, a cooling fluid is actively pumped to the battery cells for cooling purposes.

[0005] For implementing such cooling, cooling concepts are known from the prior art, in which heat sinks through which a cooling fluid can flow are provided, which are arranged next to or between the battery cells. Such concepts, in which porous metal foams are used as the material for the heat sink, are known from DE 10 2018 131 951 A1, WO 2020 / 223 747 A1, and DE 10 2009 001 592 A1.

[0006] Another problem with electrical energy storage systems is that the volume of the battery cells does not always remain constant over their lifetime. Such volume expansion, also known as "swelling," can occur during charging and discharging. Age-related volume expansion of the battery cells also often occurs. Such volume increases or expansions must be taken into account when considering the installation space.

[0007] The invention has for its object to provide an improved concept in connection with an energy storage device of a motor vehicle, in particular with regard to cooling and the problem of swelling.

[0008] According to the invention, the object is achieved in an energy storage device of the type mentioned at the outset in that at least one section of the cooling device is plastically or elastically deformable, so that a charging cycle and / or age-related expansion of the adjacent battery cell or the adjacent battery cells causes a deformation of the cooling device in such a way that the cross section of the cooling fluid guide section is reduced at least in sections.

[0009] The present invention provides a common and synergistic solution to both of these problems. Thus, the cooling fluid guide section, which in particular forms a cooling channel, contains, on the one hand, the cooling fluid for cooling the battery cell. On the other hand, the cooling fluid guide section serves as a compensating volume that enables volume compensation in the event of an expansion-related, particularly lateral, increase in volume of the battery cell. The cooling fluid can be a cooling liquid, such as water and / or glycol.

[0010] The occurrence of swelling causes an expansion or enlargement of the volume of the battery cell and an increasing space requirement for the same. In the energy storage device according to the invention, this increasing space requirement is compensated or balanced, in particular completely, by reducing the cross-section of the cooling fluid guide section. Thus, the increase in the volume of the battery cell leads to at least local deformation of the cooling device, so that a constriction or tapering occurs in the corresponding region of the cooling fluid guide section. In summary, the expansion of the battery cell causes a reduction in the size of the cooling fluid guide section, partially or completely compensating for this increase.

[0011] It is conceivable that the plastic or elastic deformation of the cooling device occurs because otherwise no escape volume would be available for the battery cell. For this purpose, the at least one battery cell and the cooling device are preferably arranged without play in a receiving space provided inside the energy storage housing. It is also conceivable that the energy storage housing has a higher mechanical strength than the plastically or elastically deformable section of the cooling device, so that the expanding battery cell almost exclusively causes a corresponding deformation of the cooling device, but not of the energy storage housing.

[0012] The functionality of the cooling fluid guide section with regard to guiding the cooling fluid is not fundamentally impaired by the reduction in size. Thus, the volume flow of the cooling fluid required to achieve a sufficiently high cooling performance can in principle be generated even if the cross-sectional size of the cooling fluid guide section is reduced, namely by at least locally increasing the flow velocity. For this purpose, a coolant pump with correspondingly sufficient power must be provided. Furthermore, to maintain the cooling effect, it is necessary that the structural integrity of the cooling device and in particular of the cooling fluid guide section, in particular with regard to fluid tightness, is maintained. This is achieved by the expansion of the battery cell causing the plastic or elastic deformation of the cooling device.This means that the material of the cooling device, at least in the area affected by the deformation, is sufficiently elastic, flexible or tough so that a deformation occurring as part of a typically occurring expansion of the battery cell does not lead to a material fracture.

[0013] The battery cell can comprise a battery cell housing into which an active material unit is inserted. The active material unit forms the electrochemically active part of the battery cell for generating a voltage difference. The active material unit is in particular layered and can implement a lithium-ion accumulator or another battery type. The active material unit is the part of the battery cell that causes the swelling. The battery cell can also have exclusively the active material unit, so that in particular no battery cell housing is provided, so that the active material unit is arranged directly adjacent to the cooling device. If the battery cell housing is provided, it is mechanically such and in particular sufficiently flexible that the occurrence of swelling in the active material unit is not inhibited or only slightly inhibited by it.

[0014] Particularly preferably, the battery cell or at least one of the battery cells and the cooling device or at least one of the cooling devices are plate-shaped. The term “plate-shaped” means that an extension of the respective component with respect to a plane is significantly greater, in particular more than ten times greater, than its extension perpendicular to this plane. Thus, the plate-shaped component has two opposing, large-area outer surfaces that essentially form the plate surfaces and are significantly larger than the remaining, lateral outer surfaces of this component. In the at least one pair comprising the cooling device or one of the cooling devices and the battery cell arranged adjacent thereto, the respective plate surfaces are arranged directly adjacent to one another and are preferably in contact with one another. This achieves the most effective heat transfer possible.

[0015] The battery cell or at least one of the battery cells and the cooling device can be rectangular or cuboid-shaped. This means that the outer surfaces have a rectangular shape. Generally, the large-area outer surfaces can have a polygonal shape. Thus, the at least one battery cell and the cooling device, or their large-area outer surfaces, can be hexagonal, in particular.

[0016] Particularly preferably, a plurality of battery cells are provided, wherein the cooling device or at least one of the cooling devices is arranged between at least two of the battery cells. The battery cells can form a cell stack into which the at least one cooling device is integrated. Thus, one of the battery cells can be arranged on opposite sides of the at least one cooling device. Preferably, the battery cells and the cooling device or the cooling devices are arranged next to one another, in particular alternately, in series.

[0017] If the battery cell or at least one of the battery cells and the cooling device are rectangular or cuboid-shaped, the resulting cell stack also has the shape of a cuboid. If a hexagonal shape is provided in this regard, the resulting cell stack has the shape of a prism with a hexagonal base. The receiving space of the energy storage housing and the cell stack preferably have the same dimensions or are identical in terms of their geometric shape.

[0018] Preferably, at least one holding element is arranged at least in sections between the battery cells between which the cooling device is arranged, wherein the holding element or at least one of the holding elements specifies the distance between the respective battery cells and holds the cooling device. The holding element performs several functions, namely, on the one hand, the holding and fastening of the respective cooling device and, on the other hand, the specifying and maintaining a required distance between the two adjacent battery cells between which the respective cooling device is arranged. The holding element forms a mechanical link between the cooling device and the battery cells adjacent to it. The holding element can also be fastened to the energy storage housing.Clamping, welding or screw connections or the like can be provided for fastening the cooling device and / or the battery cells to the holding element and / or the holding element to the energy storage housing.

[0019] Viewed in cross-section, the holding element can be one-piece or multi-piece, in particular two-piece. In the case of the multi-piece holding element, the holding element can comprise a first component and a second component. To attach the cooling device to the holding element, the cooling device can be brought together with the first component. This means that the cooling device is placed in a correspondingly provided position on the first component. Subsequently, a second component of the holding element can be connected to the first component, for example by means of a clip connection, to form a connection between the holding element and the cooling device.

[0020] It is conceivable that the holding element or at least one of the holding elements is a holding frame that laterally borders the cooling device. According to this embodiment, the cooling device, in particular the large-area outer surface, has a central region, in particular a flat one, and an outer region that laterally borders the central region, wherein the holding frame is arranged or fastened to the outer region or to the lateral outer surfaces. The flange, if present, extends in particular along the outer region or along the lateral outer surfaces. According to this embodiment, a large part of the transfer of heat to the respective battery cell to the cooling device takes place in the central region, while the outer region mainly serves for the connection to the holding frame.The geometric shape of the support frame and the geometric shape of the cooling device or the external area are adapted to each other and, in particular, correspond to each other. The support frame can have a polygonal shape, in particular rectangular or hexagonal. With respect to the circumferential direction, the support frame can be continuous or interrupted. If the support frame is interrupted, its individual parts can be successively attached to corresponding designated areas of the flange for assembly.

[0021] It is also conceivable or alternatively that the holding element or at least one of the holding elements is or comprises at least one holding strip arranged on one side of the cooling device. Analogous to the embodiment in which the holding element is the holding frame, according to this embodiment too the holding strip is arranged on the outer region or on the or one of the lateral outer surfaces or is fastened thereto. The holding strip can form a section of the holding frame, for example if the latter is interrupted. The holding strip can be rectilinear and in particular extend along a rectilinear outer surface.

[0022] The holding element or at least one of the holding elements can have a T-shape when viewed in cross-section, with the longitudinal bar of the T-shape extending between the adjacent battery cells and being connected to the cooling device, with the transverse bar of the T-shape resting laterally on the adjacent battery cells. Thus, the longitudinal bar preferably extends along the large outer surfaces, and the transverse bar along the lateral outer surfaces. The width of the longitudinal bar defines the distance between the two adjacent battery cells.

[0023] The cooling device can have a laterally projecting flange, which is inserted into a groove of the T-shaped longitudinal beam to connect the cooling device to the holding element. The groove and the flange inserted, in particular pushed, therein preferably extend perpendicular to the T-shaped cross section of the holding element. The flange extends laterally projecting, in particular continuously or interruptedly, along an outer circumference of the cooling device. The flange can be fastened in the groove. For example, the flange can be clamped in the groove by the flange having a slightly greater width than the groove. Additionally or alternatively, the fastening can be realized by means of an adhesive connection.

[0024] It is conceivable that the cooling fluid guide section is open towards the adjacent battery cell, so that the cooling fluid guided there comes into direct contact with this battery cell. According to this embodiment, the cooling fluid guide section, in which the cooling fluid is guided, is delimited to the outside not only by components or sections of the cooling device, but also by the battery cell, in particular by an outer wall of the battery cell. Thus, the cooling fluid and the battery cell come into direct contact with one another, thereby increasing heat transfer. A further fluid-tight boundary of the cooling fluid guide section can be realized by means of the holding element, which can seal it laterally in a fluid-tight manner.

[0025] It is conceivable that the cooling fluid guide section is sealed off from the adjacent battery cell in a fluid-tight manner, in particular by means of at least one film. Heat is thus transferred via the film, which has sufficient thermal conductivity for the present purposes. The film can be made of a plastic and / or a metal, such as aluminum. The use of the film ensures the most reliable fluid tightness possible without the need for separate and complex sealing means. Several films are conceivable, which are attached to one another laterally, for example. A single, folded film is also conceivable, with sections of the film being attached to one another on the sides where the fold is not provided.

[0026] If the cooling fluid guide section is sealed fluid-tight from the adjacent battery cell by means of the film or at least one of the films and the cooling device has the laterally projecting flange, then it is preferably provided that the flange is formed by means of the film or at least one of the films. In this embodiment, the film realizes several functionalities, namely the realization of the fluid-tightness of the cooling fluid guide section and the fastening of the cooling device to the respective holding element. It is preferably provided that the film or at least one of the films forms a receiving pocket for the cooling fluid guide section, which is closed by means of a sealing seam and is arranged in the region of the flange. The sealing seam can be formed, for example, by welding or gluing.

[0027] Preferably, at least one cooling fluid guide body is arranged in the cooling fluid guide section or the cooling fluid guide section is formed from at least one cooling fluid guide body, wherein the at least one cooling fluid guide body consists of an open-pored material through which the cooling fluid can be guided. At least a large part of the pores of the material are interconnected or fluidly communicate with one another, such that the cooling fluid flowing through the cooling fluid guide section or the cooling fluid guide body flows through the pores accordingly. The open-pored material thus has a sponge-like structure, wherein the pores form cavities arranged between material webs and bridges, which impart structural integrity or mechanical stability to the cooling fluid guide body.

[0028] The open-pore material is preferably a metal foam, in particular an aluminum, copper, zinc, lead, and / or iron foam. Metals have advantageous properties for the present purposes, particularly with regard to mechanical strength, elastic and plastic behavior, and thermal conductivity. Aluminum, in particular, is also advantageous due to its low density, thus enabling a lightweight construction of the energy storage device. In addition to or as an alternative to the film, it is conceivable for the cooling fluid guide section to be fluid-tightly sealed from the adjacent battery cell via a closed side surface of the cooling fluid guide body. This can be produced by foaming the starting metal against a plate, creating a closed surface on this side.

[0029] According to the invention, it can be provided that in the region of the cooling fluid guide section or at least one of the cooling fluid guide sections, at least one buffer element is arranged, which mechanically counteracts the reduction in the cross-section of the cooling fluid guide section due to the expansion of the adjacent battery cell or the adjacent battery cells, in particular in addition to the cooling fluid guide body. The buffer element can be made of a metal and / or a plastic. The buffer element serves the purpose of counteracting excessive compression of the cooling fluid guide section or the cooling fluid guide body, so that even in the event of significant swelling, the functionality of the cooling fluid guide section, namely to guide the amount of cooling fluid required to achieve a sufficient cooling effect, is maintained.Thus, in the early stages or at the beginning of swelling, i.e., when the expansion of the battery cell is still small, an elastic effect that counteracts this expansion can be generated exclusively or primarily by means of the cooling fluid guide body. If this expansion exceeds a limit, the expanding battery cell can come into sufficient active contact with the buffer element, so that this elastic effect is additionally or alternatively generated by the at least one buffer element.

[0030] It is conceivable that several buffer elements are provided, each arranged at a specific location in the cooling fluid guide section. Thus, counterforces generated by the buffer elements act locally and almost punctually on the battery cell. The buffer elements can therefore be described as almost point-like.

[0031] Additionally or alternatively, it is conceivable that at least one buffer element extending planarly in the cooling fluid guide section, which in particular is or comprises a grid, is provided. The buffer element can be or comprise a grid extending along a plane, wherein the grid also extends along a spatial direction perpendicular to this plane. Compression of the grid with respect to this spatial direction causes the counterforce. Consequently, the force generated by the buffer element acts on the battery cell planarly.

[0032] In the energy storage device according to the invention, it can be provided that the cooling device has at least one supply element for supplying the cooling fluid into the cooling fluid guide section and at least one discharge element for discharging the cooling fluid from the cooling fluid guide section. The supply element and / or the discharge element can extend through the fluid-tight film and / or the fluid-tight, closed side surface of the cooling fluid guide body and / or the holding element. Preferably, the supply element is a supply nozzle and / or the discharge element is a discharge nozzle. It is conceivable that the supply nozzle and the discharge nozzle or connecting tabs, on which the supply nozzle and the discharge nozzle are respectively arranged, extend either in the same direction, in particular upwards or downwards, or in opposite directions, in particular laterally, away from the cooling fluid guide section.

[0033] Furthermore, the present invention relates to a motor vehicle comprising an electric machine and an energy storage device connected to the electric machine according to the preceding description, wherein the electric machine is configured to generate a traction torque for the motor vehicle using electrical energy stored in the energy storage device. All advantages, features, and aspects explained in connection with the energy storage device according to the invention are equally applicable to the motor vehicle according to the invention and vice versa.

[0034] It is conceivable that the traction torque is generated exclusively by the electric motor, making the motor vehicle a purely electric vehicle. It is also conceivable that the traction torque is also generated by an internal combustion engine, making the motor vehicle a hybrid vehicle.

[0035] The motor vehicle according to the invention can have a cooling system forming a cooling circuit and carrying the cooling fluid, into which the cooling fluid guide section is integrated. It is conceivable that at least one coolant pump for driving the circulation of the cooling fluid and, if appropriate, at least one cooling device, such as a condenser or a heat exchanger, by means of which heat can be dissipated from the cooling fluid, is integrated into the cooling circuit.

[0036] Further advantages, features, and details of the present invention will become apparent from the following exemplary embodiments and from the accompanying drawings. These schematically show: Fig. 1 a schematic plan view of a motor vehicle according to the invention according to an embodiment with an energy storage device according to the invention according to an embodiment, Fig. 2 Components of a cell stack of the energy storage device of the motor vehicle of the Fig. 1 according to a first variant, Fig. 3 a sectional view of an upper area of the cell stack of the Fig. 2, where the intersection line through III - III in Fig. 2 is indicated, Fig. 4 Components of a cell stack of the energy storage device of the motor vehicle of the Fig. 1 according to a second variant, Fig. 5 a sectional view of an upper area of the cell stack of the Fig. 4, where the intersection line through V - V in Fig. 4 is indicated, Fig. 6 a sectional view of the cell stack of the Fig. 2 before the occurrence of swelling, with the section line through III - III in Fig. 2 is indicated, Fig. 7 the same sectioned view of the cell stack of the Fig. 2 like Fig. 6, namely after the occurrence or during the occurrence of swelling, Fig. 8 an enlarged view of the Fig. 7 by means of the box VIII marked area, wherein a cooling device of the energy storage device is provided according to a first alternative, and Fig. 9 an enlarged view of the Fig. 7 by means of the box VIII marked area, wherein a cooling device of the energy storage device is provided according to a second alternative.

[0037] Fig. 1 shows a schematic plan view of a motor vehicle 1 according to the invention according to an exemplary embodiment, wherein the motor vehicle 1 is an electric vehicle and thus comprises an electric machine 2 provided for generating a traction torque. The traction torque can be transmitted from the electric machine 2 via a drive train 3 to the wheels of the motor vehicle 1. Optionally, the motor vehicle 1 additionally comprises an internal combustion engine for generating the traction torque.

[0038] For storing electrical energy required to operate the electric machine 2, the motor vehicle 1 comprises a rechargeable energy storage device 4 according to the invention according to an exemplary embodiment. The energy storage device 4 comprises a plurality of battery cells 5. These are accommodated in an interior of a cuboid-shaped energy storage housing 6 made of a metal, in this case steel, wherein the interior forms a corresponding receiving space 15. For cooling the energy storage device 4, the same comprises a plurality of cooling devices 7. The battery cells 5, together with the cooling devices 7, form a cell stack 16 arranged in the receiving space 15 in a form-fitting manner, i.e., free of play. Fig. 1 only four battery cells 5 and five cooling devices 7 are indicated, corresponding cell stacks 16 typically have a significantly higher number of these components 5, 7.

[0039] The energy storage device 4, or the cooling devices 7, each of which forms a cooling channel, are integrated into a cooling system 8 of the motor vehicle 1, which forms a cooling circuit and carries a cooling fluid. The cooling fluid circulating in the cooling system 8 is, for example, a water-glycol mixture. The cooling system 8 has a coolant pump 9, by means of which the cooling fluid can be conveyed, and a cooling device 10, which is, for example, a condenser and / or a heat exchanger and by means of which heat can be removed from the cooling fluid. The energy storage device 4 has a supply interface 12, via which the cooling fluid can be supplied to the energy storage device 4, and a discharge interface 11, via which the cooling fluid can be removed from the energy storage device 4. A distribution unit 14 distributes the cooling fluid supplied via the supply interface 12 to the cooling chambers 7.A collection unit 13 brings the cooling fluid distributed over the cooling chambers 7 together to the discharge interface 11 after it has flowed through the cooling chambers 7.

[0040] The following is based on reference to Fig. 2 explains the structure of the cell stack 16 according to a first variant. Fig. 2 shows only one of the battery cells 5 and one of the cooling devices 7, whereby the aspects explained therein apply equally to the remaining battery cells 5 and cooling devices 7. The battery cells 5 and the cooling devices 7 of this cell stack 16 are arranged alternately in a row next to one another. Thus, one of the cooling devices 7 is arranged between each two adjacent battery cells 5 and between each of the two end battery cells 5 and a side wall of the energy storage housing 6.

[0041] The battery cells 5 and the cooling devices 7 are cuboid- and plate-shaped, with the two largest and thus largest-area outer surfaces of the respective components 5, 7 being arranged directly adjacent to one another in order to achieve the most effective heat transfer possible from the battery cell 5 to the cooling device 7. The cell stack 16 also has an overall cuboid structure, which corresponds to the cuboid structure of the receiving space 15.

[0042] Fig. 3 shows a representation of a cross section of the cell stack 16, wherein the cutting plane in Fig. 2 is indicated by the line III-III. The interior of the cooling device 7 forms a cooling fluid guide section 17, within which the cooling fluid can be guided. Arranged in the cooling fluid guide section 17 is a cooling fluid guide body 18, which consists of an open-pored and thus sponge-like material through which the cooling fluid flows. The pores communicate fluidically with one another, so that the cooling fluid flows through the channel system formed by the pores of the cooling fluid guide body 18.

[0043] It is conceivable that the cooling fluid guide section 17, in particular the cooling fluid guide body 18, is open towards the respective adjacent battery cell 5, so that the cooling fluid guided in the cooling fluid guide section 17 comes into direct contact with this battery cell 5. In the present embodiment, however, it is provided, which is particularly evident from the Fig. 3 shows that the cooling fluid guide section 17 is sealed fluid-tight from the adjacent battery cells 5 and the side wall of the energy storage housing 6 by means of one of two films 19, 20. The films 19, 20 are made of a plastic and / or a metal. It is also conceivable, or alternatively, for the cooling fluid body 18 to have closed and thus fluid-tight side surfaces. In the present case, the films 19, 20 are sealed circumferentially at the edges via a sealing seam, for example, by welding or gluing. The films 19, 20 thus form a sealed bag or a sealed receiving pocket, the interior of which forms the cooling fluid guide section 17 comprising the cooling fluid guide body 18. The circumferential edges of the films 19, 20 form a laterally projecting flange 21 of the cooling device 7.

[0044] With further reference to Fig. 2 shows that the cooling device 7 has a supply element 22 designed as a supply nozzle for supplying the cooling fluid into the cooling fluid guide section 17 and a discharge element 23 designed as a discharge nozzle for discharging the cooling fluid from the cooling fluid guide section 17. The elements 22, 23 are each arranged on a connection tab 24 that protrudes laterally from the area between the adjacent battery cells 5 and is formed from the films 19, 20. The elements 22, 23 reach through or penetrate the films 19, 20 into the interior of the receiving pocket. The connection tabs 24 extend in the same direction, namely upwards, for example. The supply element 22 and the supply interface 12 are connected to one another via the distribution unit 14. The discharge element 23 and the discharge interface 11 are connected to one another via the collection unit 13.

[0045] For holding and fastening each of the cooling devices 7, a holding element 25 is provided, which is arranged in sections between each two adjacent battery cells 5 together with the respective cooling device 7. The holding element 25 also specifies and maintains the distance between the respective battery cells 5. The holding element 25 is a holding frame 29 that laterally surrounds the cooling device 7 and is interrupted in the area of each of the connection tabs 24. In particular, based on the Fig. 3 shows that the holding element 25, viewed in cross-section, has a one-piece T-shape, with a longitudinal bar 26 of the T-shape extending between the adjacent battery cells 5, with a transverse bar 27 of the T-shape resting on the lateral end faces of these battery cells 5. Connections not shown in detail, such as screw connections, can be provided to fasten the holding element 25 to the battery cells 5.

[0046] To hold the cooling device 7 by means of the holding element 25, the latter is connected to the longitudinal beam 26. The holding element 25 has for this purpose a perpendicular to the plane of the drawing of the Fig. 3 and thus to the T-shaped cross section, into which groove 28 the flange 21, which also extends along this direction, is inserted, in particular clamped and / or glued. Because the sealing seam sealing the cooling fluid guide section 17 is formed in the region of the flange 21, the fastening of the flange 21 in the groove 28 provides additional protection with regard to the fluid tightness of the cooling fluid guide section 17. If the films 19, 20 were not provided, the holding element 25 can form a fluid-tight closure of the cooling fluid guide section 17.

[0047] The following is based on the Fig. 4 and Fig. 5, which Fig. 2 and Fig. 3, a cell stack 16 according to a second variant is explained. In principle, the conditions applicable in connection with the first variant or based on the Fig. 2 and Fig. 3 apply equally to the second variant, except for the differences explained below. One of the differences concerns the elements 22, 23 and the connecting lugs 24. The connecting lugs 24 according to the second variant extend laterally and in opposite directions away from the battery cells 5.

[0048] A further difference is that a plurality of holding elements 25 are provided, which, according to the second variant, are holding strips 30 arranged on one side of the cooling device 7, namely on the top and bottom. The holding elements 25 are each multi-part when viewed in cross-section, namely, for example, two-part. For assembly or fastening of the cooling device 7 to the holding element 25, the cooling device 7 is placed at a correspondingly provided position on a first component 31 of the holding strip 30. Subsequently, a second component 32 of the holding strip 30 is clipped to the first component 31, forming a clamping connection between the flange 21 and the groove 28. This multi-part concept is fundamentally transferable to the first variant concerning the holding frame 29.

[0049] The following refers to Fig. 6, which shows a cross-sectional view of a part of the energy storage device 4, namely with respect to the same sectional plane as Fig. 3, where Fig. 6 shows the respective battery cells 5 and the cooling device 7 over the entire height. For reasons of clarity, Fig. 6 the energy storage housing 6 is not shown. While Fig. 6 shows the energy storage device 4 immediately after manufacture, Fig. 7 shows the same energy storage device 4, in which the battery cells 5 have expanded laterally and a so-called "swelling" has occurred. Such expansions, in particular lateral bulges, can occur during charging of the energy storage device 4 or due to aging.

[0050] The expansion of the battery cells 5 causes a deformation or reduction in the size of the cooling fluid guide sections 17 and thus of the cooling fluid guide bodies 18. This results in an at least partial reduction in the cross section of the cooling fluid guide sections 17 present in the area of expansion. Thus, the space available for the battery cells 5 is increased in this area, this increase being compensated by the reduction in the size of the cooling fluid guide sections 17.

[0051] The described deformation of the cooling fluid guide sections 17 or the cooling fluid guide bodies 18 occurs plastically or elastically, so that the cooling fluid guide sections 17 only undergo a change in their shape, while their structural integrity is maintained. This means that no material failure or breakage occurs in the area of the deformation, which in this case particularly affects the cooling fluid guide bodies 18 and the films 19, 20. The cooling effect of the cooling fluid guide sections 17 affected by the cross-sectional reduction or tapering is maintained because, due to the coolant pump 9, the throughput or volume flow of the cooling fluid flowing through the cooling fluid guide sections 17 is maintained at a sufficiently high level.

[0052] In this case, the outer contour or shape of the energy storage housing 6 remains at least approximately the same despite the deformations caused by swelling. This is achieved because the energy storage housing 6 has a higher mechanical strength than the cooling devices 7, in particular than the cooling fluid guide bodies 18. This difference in mechanical strength results from the use of different materials, namely steel for the energy storage housing 6 and aluminum foam for the cooling fluid guide bodies 18.

[0053] A further aspect of the present embodiment will be explained below with reference to the Fig. 8 and Fig. 9 explained. Fig. 8 shows, with respect to the cooling device 7, a first and Fig. 9 a second alternative, whereby all aspects explained so far are generally applicable to both alternatives. Fig. 8 and Fig. 9 each show an enlarged view of the Fig. 7 area marked by the dashed box VIII.

[0054] In both alternatives, at least one buffer element 33 is arranged in the cooling fluid guide section 17. This buffer element mechanically counteracts the reduction in the cross-section of the cooling fluid guide section 17 due to the expansion of the adjacent battery cells 5. When swelling occurs, or as soon as the expansion of the battery cells 5 exceeds a certain limit, the buffer element 33 is compressed, which, as a corresponding reaction, generates a counterforce, in particular an elastic one, which prevents the cross-section of the cooling fluid guide section 17 from being completely closed.

[0055] According to the first alternative, the buffer elements 33 arranged in the cooling fluid guide body 18 are each arranged locally at a specific location in the cooling fluid guide section 17 and are made of a plastic. The buffer elements 33 are approximately point-shaped with respect to the large outer surfaces. Within the scope of this embodiment, the force generated by each of the buffer elements 33 on the battery cell 5 is applied almost point-like.

[0056] According to the second alternative, the buffer element 33 arranged in the cooling fluid guide body 18 is a grid 34 made of a metal that extends flatly in the cooling fluid guide section 17. The grid 34 extends along a Fig. 8, vertical and perpendicular to the plane of the drawing, and thus within the gap between the battery cells 5, in which the cooling device 7 is arranged, is planar. Furthermore, the grid also has an extension with respect to the spatial direction perpendicular to this plane, with the compression of the buffer element 33 causing the counterforce affecting this plane. According to this embodiment, the force generated by the buffer element 33 acts on the battery cell 5 in a planar manner.

[0057] With regard to both alternatives, it is provided that when swelling occurs, the battery cells 5 only come into contact with the buffer element 33 or the buffer elements 33 when the cross section of the respective cooling fluid guide section 17 falls below a limit value. Fig.In the state shown in Figure 6, there is still a gap between the buffer element 33 or the buffer elements 33 and the respective battery cells 5. In an early phase of swelling, i.e., when the expansion of the battery cells 5 is still small, the elasticity of the cooling fluid guide body 18 alone generates a counterforce that counteracts the corresponding expansion. Later, i.e., when the swelling is advanced, the counterforce is generated both by the cooling fluid guide body 18 and by the buffer element 33. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2018 131 951 A1

[0005] WO 2020 / 223 747 A1

[0005] DE 10 2009 001 592 A1

[0005]

Claims

[1] Energy storage device for a motor vehicle (1), comprising an energy storage housing (6) and at least one battery cell (5) accommodated therein, wherein at least one cooling device (7) is arranged adjacent to the battery cell (5) or to at least one of the battery cells (5) in such a way that this battery cell (5) can be cooled by means of a cooling fluid guided in at least one cooling fluid guide section (17) of the cooling device (7), characterized by that at least one section of the cooling device (7) is plastically or elastically deformable, so that a charging cycle- and / or age-related expansion of the adjacent battery cell (5) or the adjacent battery cells (5) causes a deformation of the cooling device (7) such that the cross section of the cooling fluid guide section (17) is reduced at least in sections. [2] Energy storage device according to claim 1, characterized bythat the battery cell (5) or at least one of the battery cells (5) and the cooling device (7) or at least one of the cooling devices (7) are plate-shaped. [3] Energy storage device according to claim 1 or 2, characterized by that a plurality of battery cells (5) are provided, wherein the cooling device (7) or at least one of the cooling devices (7) is arranged between at least two of the battery cells (5), wherein it is provided in particular that the plate-shaped battery cells (5) form a cell stack (16). [4] Energy storage device according to claim 3, characterized by that between the battery cells (5) between which the cooling device (7) is arranged, at least one holding element (25) is arranged at least in sections, wherein the holding element (25) or at least one of the holding elements (25) specifies the distance between the respective battery cells (5) and holds the cooling device (7). [5] Energy storage device according to claim 4, characterized by that the holding element (25) or at least one of the holding elements (25) - a holding frame (29) laterally surrounding the cooling device (7), in particular continuous or interrupted, and / or - at least one retaining strip (30) arranged on one side of the cooling device (7) is or comprises. [6] Energy storage device according to claim 4 or 5, characterized by that the holding element (25) or at least one of the holding elements (25) has a T-shape when viewed in cross-section, wherein the longitudinal bar (26) of the T-shape extends between the respectively adjacent battery cells (5) and is connected to the cooling device (7), wherein the transverse bar (27) of the T-shape rests laterally on the respectively adjacent battery cells (5). [7] Energy storage device according to claim 6, characterized bythat the cooling device (7) has a laterally projecting flange (21) which is inserted into a groove (28) of the longitudinal beam (26) of the T-shape for connecting the cooling device (7) to the holding element (25). [8] Energy storage device according to one of the preceding claims, characterized by that the cooling fluid guide section (17) is open towards the adjacent battery cell (5), so that the cooling fluid guided there comes into direct contact with this battery cell (5), and / or that the cooling fluid guide section (17) is sealed in a fluid-tight manner towards the adjacent battery cell (5), in particular by means of at least one film (19; 20). [9] Energy storage device according to claim 7 and 8, wherein the cooling fluid guide section (17) is sealed fluid-tight from the adjacent battery cell (5) by means of the film (19, 20) or at least one of the films (19, 20), characterized bythat the flange (21) is formed by means of the film (19, 20) or at least one of the films (19, 20). [10] Energy storage device according to claim 9, characterized by that the film (19, 20) or at least one of the films (19, 20) forms a receiving pocket for the cooling fluid guide section (17) closed by means of a sealing seam, wherein the sealing seam is arranged in the region of the flange (21). [11] Energy storage device according to one of the preceding claims, characterized by that at least one cooling fluid guide body (18) is arranged in the cooling fluid guide section (17) or the cooling fluid guide section (17) is formed from at least one cooling fluid guide body (18), wherein the at least one cooling fluid guide body (18) consists of an open-pore material, in particular of a metal foam, through which the cooling fluid can be guided. [12] Energy storage device according to one of the preceding claims, characterized bythat in the region of the cooling fluid guide section (17) or at least one of the cooling fluid guide sections (17) at least one buffer element (33), in particular made of a metal and / or a plastic, is arranged, which mechanically counteracts the reduction in the cross section of the cooling fluid guide section (17) due to the expansion of the adjacent battery cell (5) or the adjacent battery cells (5). [13] Energy storage device according to claim 12, characterized by that a plurality of buffer elements (33) are provided, each arranged locally at a location in the cooling fluid guide section (17), and / or that at least one buffer element (33) extending flatly in the cooling fluid guide section (17), which in particular is or comprises a grid (34), is provided. [14] Energy storage device according to one of the preceding claims, characterized bythat the cooling device (7) has at least one feed element (22) for feeding the cooling fluid into the cooling fluid guide section (17) and at least one discharge element (23) for discharging the cooling fluid from the cooling fluid guide section (17), wherein it is provided in particular that the feed element (22) is a feed nozzle and / or that the discharge element (23) is a discharge nozzle. [15] Motor vehicle, comprising an electric machine (2) and an energy storage device (4) connected to the electric machine (2) according to one of the preceding claims, wherein the electric machine (2) is designed to generate a traction torque for the motor vehicle (1) by means of electrical energy stored in the energy storage device (4).

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