High-voltage storage for a motor vehicle

Abstract

The invention relates to a high-voltage storage device (10) for a motor vehicle (50), comprising a cell pack (15) of battery cells (16) which are received in an interior space (14) bounded by a housing (11) of the high-voltage storage device (10), wherein the battery cells (16) are embedded in a structural medium (19). The invention also relates to a method (100) for manufacturing such a high-voltage storage device (10).

Description

[0001] The invention relates to high-voltage storage devices for a motor vehicle, comprising a cell pack of battery cells which are contained in an interior space bounded by a housing of the high-voltage storage device, wherein the battery cells are partially embedded in a structural medium. The invention also relates to a method for manufacturing such a high-voltage storage device.

[0002] High-voltage storage systems, also known as traction batteries or accumulators, are used to provide electrical energy for powering electric vehicle drives. A vehicle battery or high-voltage storage system typically comprises battery cells connected in parallel and series, arranged in packing configurations. Electrically conductive cell connectors or cell contacting devices can be used to connect the battery cells. These connectors can be connected to the end faces of several battery cells in a cell row of the packing configuration. To join these cell connectors and the battery cells into a mechanically stable unit, the interior of the housing, and thus the cavities between the packing configuration and the cell connectors, is filled with a structural compound or foam.

[0003] Since these battery cells can release a considerable amount of energy in a thermal event, such as an internal short circuit, the battery cells of a high-voltage storage system, especially lithium-ion batteries, have predetermined breaking points or vents that serve as a safety mechanism. These vents allow gases to escape that can form under predetermined conditions, such as overcharging, overheating, or an internal short circuit. These high-temperature and high-pressure gases, as well as liquid and solid impurities, must be vented quickly and effectively, even in the presence of structural foam.

[0004] Against this background, an object of the invention is to improve a high-voltage storage device for a motor vehicle. In particular, the high-voltage storage device is to be improved in such a way as to enable improved dissipation of a degassing flow from at least one battery cell, in particular to improve the safety of the high-voltage storage device.

[0005] This problem is solved by a high-voltage storage device for a motor vehicle with the features of claim 1 and a method for manufacturing a high-voltage storage device with the features of claim 8. The dependent claims relate to advantageous further developments of the invention.

[0006] According to a first aspect, a high-voltage storage device for a motor vehicle is specified, comprising a cell pack of battery cells which are contained in an interior space bounded by a housing of the high-voltage storage device, wherein the battery cells are embedded in a structural medium such that at least one region of the battery cells is arranged in a volume of the interior space free of structural medium.

[0007] The structural medium can, for example, form a plane or layer of a predetermined height in which the battery cells or cell pack are partially contained or embedded, particularly along the longitudinal axes of the battery cells. This allows for the separation of internal areas by means of the structural medium, enabling, for example, the separation of an internal area intended for degassing from an internal area without a structural medium, i.e., the free volume. This allows for the separation of safety-relevant areas of the batteries.Cell packing components, such as electrical connections with a cell contacting device, are surrounded by the structural medium. The proposed partial foaming separates the degassing space from the remaining free air volume of the storage unit. This allows live components to be separated from the degassing space by the layer of structural medium, particularly in the case of cell propagation. This prevents secondary short circuits between adjacent battery cells and thus improves the safety of the battery cells, the cell packing, and / or the high-voltage storage unit.

[0008] A high-voltage battery is, in particular, an energy storage device or traction battery for a motor vehicle, comprising multiple battery cells. The housing of the high-voltage battery defines an interior space in which the battery cells or battery cell array are housed. Cylindrical or prismatic battery cells are primarily used, which can be arranged in a cell pack. A cylindrical battery cell, for example, can have a circular cross-section and a longitudinal axis perpendicular to it, and can be bounded longitudinally by two end faces, which are connected by a cell shell or surface. Of course, battery cells with other cross-sections, such as rectangular, hexagonal, or prismatic cross-sections, can also be used.

[0009] In a vehicle installation, the high-voltage storage system and / or battery cells can be arranged such that the longitudinal axes of the battery cells are parallel to a vehicle vertical. Typically, such a battery cell has a geometrically distinct or slightly raised first electrical pole or cell terminal on one of its end faces or first side for electrical contact via the cell contacting device. The remaining part of the end face or first side, as well as the cell shell of the battery cell, can form the second electrical pole of the battery cell. The portion of the end face surrounding the cell terminal, or this area of ​​the second electrical pole, forms a so-called cell shoulder.In other embodiments, particularly in prismatically shaped battery cells, the second electrical pole can also be designed as a separately shaped second cell terminal.

[0010] A predetermined breaking point or a degassing opening provided by means of the predetermined breaking point can be provided to interrupt the current flow to and / or from a damaged or failing battery cell. The degassing opening is designed to release gases, particles, and / or internal components of the battery cell that may form during overcharging, overheating, and / or an internal short circuit. The predetermined breaking point or degassing opening is designed, in particular by means of at least one safety valve and / or predetermined breaking point integrated into the cylindrical battery cell, to release the degassing flow from a predetermined internal pressure, in particular in a predetermined direction or in a controlled manner, without the battery cell itself rupturing or exploding. Such degassing prevents the increasing pressure from causing the cell to burst or explode.Opening the battery cell at a different location, where degassing cannot be controlled, can lead to secondary failures.

[0011] The invention is based, among other things, on the idea of ​​applying a structural medium in a foaming process only in areas of an energy cluster or cell pack that have an increased structural-mechanical safety requirement. For this purpose, it is now proposed to embed the battery cells in a structural medium such that their electrical poles, and in particular a cell contacting device attached to or arranged thereon, are enclosed by the structural medium, while a further area of ​​the battery cells remains free of structural foam or structural medium. This area can be located, in particular, on a lateral surface along its longitudinal extent, or at least a region along the longitudinal axis of the battery cells extending from an end face opposite the electrical poles.This allows for partial foaming of the battery cells and the cell contacting system, which can save costs or weight, particularly through the use of a reduced amount of foam material.

[0012] In one embodiment, each battery cell has a predetermined breaking point to provide a degassing opening, wherein this predetermined breaking point is arranged on a first side of the respective battery cell, which has at least one of the two electrical poles, in particular both electrical poles, of the battery cell for electrical contact. The degassing opening can have a circular or otherwise shaped cross-section and / or is arranged on a battery cell, in particular on at least one of the end faces, in order to prevent other battery cells from being directly exposed to the degassing flow during a degassing process and to direct this flow towards the housing. Such a degassing opening can be located in the area of ​​the electrical poles or...The predetermined breaking point is arranged on an end face of the battery cell, which has a first electrical pole designed as a cell terminal for electrical contact, and a second electrical pole for electrical contact with a cell contacting device. In some embodiments, the predetermined breaking point can be arranged on the battery cell independently of the poles, in particular on a side with one or no pole.

[0013] In one embodiment, the predetermined breaking point is arranged, in particular, radially spaced from the cell terminal. Here, the predetermined breaking point or the degassing opening can be located in a region of a cell shoulder adjacent to the cell terminal, whereby opening of the predetermined breaking point or the degassing opening can cause movement of the cell terminal and thus, in particular, also of a cell contacting device connected to the cell terminal. This can cause, or at least facilitate, a mechanical separation of the cell contacting devices when the predetermined breaking point opens, in order to interrupt the current flow between the damaged battery cell or the battery cell opened for degassing and other surrounding or adjacent battery cells.This allows short-circuit currents that can flow from the damaged battery cell to another battery cell to be interrupted, in order to prevent propagation and / or progressive damage to the high-voltage storage system.

[0014] In one embodiment, the cell contacting device is arranged on a first side of the battery cells, specifically on the side where the first electrical pole, the second electrical pole, and the predetermined breaking point of the battery cells are located. This allows the cell contacting device to be positioned in the region of the predetermined breaking point of the battery cell while simultaneously contacting the electrical poles. Therefore, if the predetermined breaking point or the vent is triggered, movement of the predetermined breaking point, the parts of the battery cell located in the region of the predetermined breaking point, and / or the escape of hot gases from the vent can cause a mechanical separation of the cell contacting device.

[0015] In one embodiment, the structural medium covers less than 50% of the height or longitudinal extent of the battery cells. It can be provided that less than 45%, less than 40%, less than 35%, less than 30%, less than 25%, or less than 20%, and / or at least 5%, 10%, 15%, or 20% of the height or longitudinal extent of the battery cells are embedded in the structural medium. In particular, a lower region of the battery cells along a vehicle vertical is embedded in the structural medium, with the electrical poles and the degassing chamber being, or being arrangable, facing a side of the high-voltage storage system away from the vehicle interior. This allows a portion of the interior facing the vehicle interior to remain free of structural medium.

[0016] In one embodiment, the structural medium fills less than 50% of the (total) volume of the interior. It can be provided that less than 45%, less than 40%, or less than 35% of the interior volume is occupied by the structural medium, so that at least some of the battery cells are arranged within a volume or air-filled volume of the high-voltage storage system. This can result in a significant weight saving.

[0017] In one embodiment, a support structure arranged at the end face of the battery cells is essentially free of structural medium. This support structure can be positioned between the battery cells and the housing and configured to define a distance between the battery cells or their degassing openings, thus defining, in particular, a degassing space within the high-voltage storage system. In some embodiments, the support structure can be foamed onto the battery cells and / or the cell contacting device using the structural medium. Because the support structure, and therefore the degassing space, is at least essentially free of structural medium, the degassing flow through the support structure can be controlled.The gas can flow from the degassing chamber to an inlet of a flow channel, flow into it, and leave the high-voltage storage unit through an outlet of the flow channel to be released into the environment of the high-voltage storage unit.

[0018] In one embodiment, the support structure is separated from the structural medium by means of a separating layer. This separating layer can be, for example, a film, a plastic layer, or a mica sheet, which may be designed to prevent foam from penetrating the area of ​​the support structure during the foaming process. This allows a degassing chamber and / or degassing areas, which may be associated with the discharge openings of the battery cells and formed by the structure, to remain free of structural medium, thus enabling unimpeded degassing of the battery cells.

[0019] In one embodiment, a degassing chamber is formed by means of the support structure, which is connected to a flow channel. This flow channel is specifically designed to direct the degassing flow from the interior, or the degassing chamber provided by the support structure, to the outside and release it into the environment. The flow channel has an inlet with a predetermined cross-sectional area through which the degassing flow can enter the flow channel, and an outlet through which the degassing flow can exit the flow channel. It can also be configured to influence at least one flow characteristic, such as velocity, pressure, and / or direction of the degassing flow, in order to achieve a desired cooling effect and / or to reduce the temperature of the degassing flow.

[0020] In one embodiment, a cell contacting device for the electrical connection of the battery cells or their electrical poles is at least partially embedded in the structural medium. In this case, the cell contacting device can be attached to or welded to the battery cells or their poles, particularly before the cell pack is arranged in the housing, in order to provide a testable battery cell pack. By encapsulating the cell contacting device together with the battery cells or the cell pack, an integrated structure can be created that can increase stress resistance and reduce the risk of propagation.

[0021] In one embodiment, the structural medium borders the free volume of the interior. The height or volume of the structural medium layer can be adjusted during or through the foaming process, thus defining the volume of the unstructured interior. In particular, this eliminates the need for a separating layer, thereby optimizing the production of the high-voltage storage device.

[0022] According to a further aspect, a method for manufacturing a high-voltage storage device is described, comprising the steps of providing a housing for the high-voltage storage device; arranging a support structure in an interior space at least partially bounded by the housing; arranging a trend layer on the support structure; arranging a cell pack of battery cells on the separating layer; and introducing a structural medium over the separating layer such that the battery cells are partially embedded in the structural medium, with at least a region of the battery cells remaining free of the structural medium. The sequence of the steps is not necessarily fixed; for example, in some embodiments, the introduction of the structural medium can take place before the arrangement of the cell pack of battery cells in the housing or interior space.

[0023] In a foaming process, the housing of the high-voltage storage system and its components, such as battery cells, the cell contacting device, and the battery cell itself, are positioned so that structural foam can spread and / or distribute evenly within the housing and around the components. The foam material and its properties, such as density, strength, and thermal characteristics, are typically selected according to the specific requirements of the high-voltage storage system, and the foam material or structural foam can typically consist of polyurethane and / or epoxy. During expansion, the structural foam can penetrate the spaces between the components of the high-voltage storage system, fill them, and harden.This allows for improved protection of the cell contacting device and the battery cell from outgassing and / or escaping particles, as well as from mechanical stresses, particularly those originating outside the high-voltage storage system. Such a foaming process can take place during an intermediate assembly stage within the housing, eliminating the need for specialized foaming tools. This method allows a section of the battery casing, positioned at a distance from the cell terminals along its length, to remain free of the structural material. This enables the electrical terminals, and especially the cell contacting device connecting these terminals, to be foamed or enclosed within the structural material, thus creating a composite structure in this area.This allows a plane to be formed by means of the structural medium, separating a free volume of the interior from a degassing space, which can be formed by means of the support structure, in order to reduce the weight of the high-voltage storage device and to improve production steps in the manufacture of the high-voltage storage device.

[0024] In one embodiment, the method includes the further steps of arranging a cell contacting device on the cell pack of battery cells and connecting the battery cells to or by means of the cell contacting device. Here, the arranging and / or connecting of the cell contacting device to the battery cells can take place before the cell pack is arranged in the housing and before the foaming process, so that the cell pack is already electrically connected and thus testable in order to detect any faulty shading of the cell pack at an early stage and thus reduce rejects.

[0025] Further advantages and application possibilities of the invention will become apparent from the following description in conjunction with the figures. Fig. Figure 1 shows a schematic representation of an embodiment of a motor vehicle according to the invention comprising a high-voltage storage device according to the invention. Fig. Figure 2 shows a schematic representation of an embodiment of a high-voltage storage device according to the invention in accordance with an exemplary embodiment of the invention. Fig. Figure 3 shows a further schematic representation of the embodiment of a high-voltage storage device according to an exemplary embodiment of the invention. Fig. Figure 4 shows a schematic flowchart of an exemplary embodiment of a method for manufacturing a high-voltage storage device according to an exemplary embodiment of the invention.

[0026] Fig. Figure 1 shows an embodiment of a motor vehicle 50 with a high-voltage storage device 10 for a motor vehicle 50 with a cell packing 15 according to the present disclosure in a schematic sectional view in the longitudinal direction of the vehicle.

[0027] The motor vehicle 50 has a high-voltage storage unit 10 in its underbody area, which comprises a housing 11 with a housing cover 12 and a housing tray 13. The housing 11 encloses or delimits an interior space 14 in which a cell pack 15 of battery cells 16 is arranged. The battery cells 16 are received in the high-voltage storage unit 10 or its housing 11 such that, on a first (end) side of the battery cells 16, recessed cell terminals 26 (first electrical pole) are arranged facing away from the housing cover 12 or a vehicle interior 57 for electrical contact. The remaining part of the first (end) side, or a cell shoulder 36, forms a second electrical pole 36 of the battery cell. The electrical poles 26 and 36 of the battery cells 16 are electrically connected to each other by means of a cell contacting device 18.

[0028] The cell contacting device 18 and the cell packing 15 are partially embedded in a structural medium 19 (illustrated by dotted lines), such that at least a region of the battery cells 26 is arranged in a volume 29 of the interior 14 free of structural medium 19. A support structure 17 is arranged between the battery cells 16 and the housing tray 13, which is configured to form a degassing chamber 37 for the battery cells 16. In this exemplary embodiment, a separating layer 27, in the form of a film, is arranged between this support structure 17 and the battery cells 16 or the structural medium 19, in order to keep the structural medium 19 out of the degassing chamber 37 during a foaming process.This allows a separation between the free air volume 29 and the degassing space 37 created by the support structure 17 to be created by means of the layer of structural medium 19, while at the same time improving the structural strength in the area of ​​the cell packing 15 and in particular the connection with the cell contacting device 18.

[0029] Fig. Figure 2 shows an enlarged detail view of the high-voltage storage unit 10. Fig. 1 in a sectional view along a transverse direction of the vehicle.

[0030] It can be seen that the cell pack 15, which is housed in the casing 11, is arranged such that the battery cells 16 are spaced apart from the casing 11 and the housing tray 13 by means of the support structure 17, thereby providing the degassing space 37 for the battery cells 16 and the cell pack 15. This degassing space 37 is separated from the structural medium 19 by the separating layer 27. The structural medium 19 surrounds the battery cells 16 and the cell contacting device 18, thus forming a mechanically stabilized structure. The structural medium 19 forms a layer that separates the degassing space 37 from the free volume 29. The structural medium 19 covers less than 50% of a height H along a longitudinal axis L of the battery cells 16 and fills less than 50% of the total volume of the interior 14. This allows the necessary mass of structural medium 19 and thus the overall weight of the high-voltage storage device 10 to be reduced.

[0031] The cell pack 15 comprises battery cells 16, each battery cell 15 having, in the present embodiment, a predetermined breaking point 46 on its end faces, which have the electrical poles 26, 36, to provide a degassing opening. The cell pack 15 also has a cell contacting device 18 arranged on this side of the battery cells 16, which electrically connects the battery cells 16. In the event of overpressure in the battery cell 16, the predetermined breaking point 46, or the area of ​​the battery cell 16 surrounded or enclosed by the predetermined breaking point 46, in particular including the cell terminal 26, can open and / or detach completely from the battery cell 16, allowing hot gases and / or particles to escape from the battery cell 16 and flow into the degassing chamber 37.Through this movement of at least part of the predetermined breaking point 46, the cell contacting device 18 can undergo mechanical separation, thereby interrupting the current flow and protecting surrounding battery cells 16 from overcurrent. The hot gases can then flow via the degassing chamber 37, which is spanned by the support structure 17, to an inlet of a flow channel 47, flow into it, and exit the high-voltage storage device 10 through an outlet 447 of the flow channel 47. In particular, live components can be separated from the degassing chamber 37 by the layer of structural medium 19, thus preventing cell propagation and / or secondary short circuits.

[0032] It may be provided that a heat exchange device 20 is arranged in the housing cover 12 and adjacent to the free volume 29 to enable heat exchange and / or a cooling effect at the battery cells 16. In some embodiments, a heat exchange device 20 may be arranged between battery cells 16 or cell rows on battery cells 16 and / or on a flat side of the cell packing 15.

[0033] Fig. Figure 3 shows an enlarged detail view of the high-voltage storage unit 10. Fig. 1 in a schematic top view.

[0034] The battery cells 16 are arranged in a hexagonal packing arrangement and electrically connected by means of the cell contacting device 18. The degassing chamber 37 can extend substantially over the entire cross-section of the high-voltage storage unit or the housing tray 12 and is connected to the flow channel 47, allowing a degassing flow to reach an inlet 448 of the flow channel 47. The flow channel 47 can function as a cooling section to sufficiently cool the degassing flow and prevent the occurrence of flames at the outlet 447 of the flow channel 47.

[0035] Fig. Figure 4 shows a schematic flowchart of a process 100 for manufacturing a high-voltage storage device 10 according to the present disclosure.

[0036] In a first step a, a housing 11 or a housing tray 13 is provided for the high-voltage storage device 10, and in a second step b, a support structure 17 is arranged in an interior space 14 that is at least partially bounded by the housing 11 or the housing tray 13. In a further step c, a separating layer 27 is arranged on the support structure 17.

[0037] In an optional step d1, a cell contacting device 18 can be arranged on a cell pack 15 on battery cells 16 and, in a further optional step d2, connected to the battery cells 16. In a further step d, the cell pack 15 on battery cells 16 is arranged on the separating layer 17, in particular such that the electrical poles 26, 36 and / or the cell contacting device 18 are adjacent to the separating layer 17. In a further step e, a structural medium 19 is introduced into the housing tray 13 above the separating layer 17 and around the battery cells 16 and the cell contacting device 18 associated therewith, such that the battery cells 17 are partially embedded in the structural medium 19 and at least one region of the battery cells 16 remains free of the structural medium 19.

[0038] This allows safety-relevant areas to be foamed using the foaming process, which takes place directly in an intermediate assembly within the housing 11, 13, thus eliminating the need for special foaming tools. Such partial foaming of the battery cells 16 can reduce costs and the weight of the high-voltage storage unit 10. REFERENCE MARK LIST 10 high-voltage storage units 11 cases 12 Case covers 13 Housing tray 14 Interior of the housing 15 cell pack 16 battery cells 17 Support structure 18 Cell contacting device 19 Structural medium 20 Heat exchanger 26 first electrical pole / cell terminal 27 Separation layer 29 free volume 36 second electrical pole / cell shoulder 37 Degassing room 46 Breakaway point / Degassing opening 47 Flow channel 50 motor vehicles 57 Vehicle interior 447 Outlet 448 Admission

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