Battery for a vehicle

Abstract

A battery (1) for a vehicle, preferably a traction battery, comprising at least one battery module (2), comprising at least two battery cells (5), preferably cylindrical battery cells (5), held in a cell holder (3, 4), which have temperature control surfaces (50) to be brought into thermally conductive contact with a temperature control element (8) of a housing (100), and a housing (100) with a temperature control element (8) for temperature control of the battery cells (5) accommodated in the at least one battery module (2), as well as a thermally conductive element (6) arranged on the temperature control element (8), characterized in that a single, electrically insulating insulation film (7) is arranged over all temperature control surfaces (50) of the battery cells (5), which provides electrical insulation between the battery cells (5) and the thermally conductive element (6), wherein the insulation film (7) is in contact with the thermally conductive element (6).

Description

Technical area

[0001] The present invention relates to a battery for a vehicle, for example a traction battery for a vehicle, according to the preamble of claim 1. State of the art

[0002] Battery systems for vehicles are usually equipped with a suitably tuned temperature control element. This temperature control element is often designed as a chamber-like base element that allows a medium, such as a liquid coolant, to flow through it. This base element is usually made of metal.

[0003] To thermally connect each individual battery cell to the temperature control element, it is known to use a thermally conductive and electrically insulating layer that can also compensate for geometric tolerances between the cells and the temperature control element. This can be a moldable mat (gap pad) or a viscous paste (gap filler). Viscous gap fillers can, for example, be applied to the temperature control element in serpentine patterns. During assembly and the associated pressing of the battery cells against the temperature control element, the distribution of the gap filler closes air gaps.

[0004] For the purposes of the present disclosure, a battery cell is understood to mean an electrochemical storage cell, preferably a secondary cell. With regard to the physical appearance of the component, the term "cell" can be understood as the smallest contactable structural unit. In contrast, a battery module is understood to mean a structural unit that combines a plurality of battery cells. Accordingly, a battery is understood to mean a structural unit that is constructed from one or more interconnected battery modules. Such battery systems can further comprise a housing accommodating the battery modules, electrical circuitry, and a battery management system. Batteries are preferably intended for use in an electric vehicle, but can also be used in other vehicles or other areas of application.

[0005] Gap fillers are divided into non-curing and application-curing systems. Non-curing systems are highly viscous, usually requiring a correspondingly high contact pressure on the cells for even distribution of the gap filler, and create the mechanical connection between the cell and the temperature control element through adhesive force. Curing systems can be adjusted to a lower viscosity for application, so that even a low contact pressure leads to even distribution. Furthermore, curing can provide a supporting or structural bond between the cell and the cooler.

[0006] The use of gap pads is usually associated with high costs, and tolerance compensation with gap pads is only possible within narrow limits, for example, in the ratio of uncompressed thickness to the thickness at maximum compression. The achievable adhesive or bonding forces between the temperature control element, gap pad, and battery cells are also limited and unsuitable for a structural connection.

[0007] The use of gap fillers, on the other hand, is more cost-effective, enables the compensation of higher tolerances, even with complex geometries, and allows the adjustment of viscosity and adhesion or bond strength to suit the respective application.

[0008] During the mixing and application of the often two-component gap fillers, as well as during the pressing of the battery cells onto the gap filler, air pockets cannot be ruled out. For prismatic battery cells, which are usually provided with an electrically insulating film at the factory, as well as for pouch cells, whose cell shells are usually floating or have an electrically insulating coating, this generally does not pose a problem with the electrical insulation between the cell and the cooler.

[0009] However, with the increasing use of cylindrical battery cells in traction batteries for electric vehicles, the following disadvantage can arise when using gap fillers: Cylindrical battery cells for automotive applications are usually delivered "bare," meaning without an electrically insulating film on the outside, which, with the exception of the lid, is then usually at cell negative potential. Therefore, air bubbles in the gap filler can lead to a violation of the specified clearance and creepage distances and thus the insulation resistance in (high-voltage) battery systems, which can represent a safety-critical failure.

[0010] DE 10 2015 120 031 A1 discloses a battery assembly with battery cells wrapped with a heat-conducting film. US 2021 / 0 218 082 A1 discloses a battery pack capable of preventing damage to the insulating layer on the underside of each battery cell and providing improved cooling performance for the battery cells. WO 2020 / 152 858 A1 discloses a battery pack and a battery system. WO 2017 / 157 968 ​​A1 discloses a battery module, wherein an electrical insulation formed as a thermal contact element is located between a busbar and a heat-conducting plate. JP 2015-207 541 A discloses a cooling structure of an energy storage device mounted on a work machine. Description of the invention

[0011] Based on the known prior art, it is an object of the present invention to provide an improved battery, preferably a traction battery for a vehicle.

[0012] The object is achieved by a battery for a vehicle having at least one battery module with the features of claim 1. Advantageous further developments emerge from the subclaims, the description, and the figures.

[0013] Accordingly, a battery for a vehicle, preferably a traction battery, with at least one battery module is proposed. The battery module comprises at least two battery cells held in a cell holder, preferably cylindrical battery cells, which have temperature control surfaces that can be brought into thermally conductive contact with a temperature control element of a housing, and a housing with a temperature control element for temperature control of the battery cells accommodated in the at least one battery module, as well as a thermally conductive element arranged on the temperature control element, wherein a single, electrically insulating insulation film is arranged over all temperature control surfaces of the battery cells, which provides electrical insulation between the battery cells and the thermally conductive element, wherein the insulation film is in contact with the thermally conductive element.

[0014] The insulation foil is arranged in such a way that it is located between the battery cells and the temperature control element and can thus achieve electrical insulation of the battery cells from the temperature control element.

[0015] An electrically insulating film is understood to be a film with low electrical conductivity and / or high dielectric strength, which is preferably a plastic film, e.g., made of PP (polypropylene), PEN (polyethylene naphthalate), PET (polyethylene terephthalate), or PI (polyimide). The film preferably has a thickness of less than 500 µm, more preferably less than 100 µm. The dielectric strength is preferably at least 10 kV / mm, more preferably at least 30 kV / mm.

[0016] A thermally conductive element is arranged on the temperature control element. In other words, the insulating film can be arranged such that, when the battery module is assembled to produce a battery, the insulating film is arranged between the battery cells and the thermally conductive element, thus providing electrical insulation between the battery cells and the thermally conductive element.

[0017] A thermally conductive element can, for example, be a thermally conductive paste (a "gap filler") or a thermally conductive and moldable mat (a "gap pad") arranged on the temperature control element to create a thermal connection between the temperature control surfaces of the battery cells and the temperature control element. In other words, the thermally conductive element is designed to thermally and mechanically connect the battery cells (compensating for any tolerances) to the temperature control element, while keeping the thermal resistance of this connection as low as possible.

[0018] Preferably, cylindrical battery cells are arranged in the battery modules, which, for example, have a non-insulated outer side.

[0019] The insulation foil is arranged on the temperature control surfaces of all battery cells. This allows all battery cells of the battery module to be efficiently electrically insulated from the temperature control element using a single insulation foil.

[0020] Preferably, the insulation foil is arranged over the entire surface of the temperature control surfaces of the battery cells.

[0021] To simplify assembly, the insulation film is preferably bonded to the temperature control surfaces of the battery cells, preferably to the temperature control surfaces of the majority of the battery cells, and particularly preferably to the temperature control surfaces of all battery cells. This bonding can simplify the assembly of the battery module.

[0022] The insulation film can have an adhesive side or a single-sided adhesive coating. This makes it easier to attach the film to the battery cells. The insulation film can, for example, be easily glued to the battery cells. Furthermore, the application of the film can be less time-consuming, material-intensive, and costly compared to, for example, individually wrapping the battery cells.

[0023] More preferably, the insulation film is arranged on the temperature-control surfaces of the battery cells and between the battery cells and the thermally conductive element, wherein the thermally conductive element is preferably a gap filler. In other words, in a battery with a battery module described above, a temperature-control element, a thermally conductive element, preferably a gap pad or a gap filler, an insulation film, and then the battery cells are provided in stacking order.

[0024] This makes it possible, for example, to select a thermally conductive element for battery production independently of its electrically insulating properties. Furthermore, it makes it possible to select a layer thickness of the thermally conductive element so thin that the required tolerance compensation is achieved. This allows a thinner layer of a thermally conductive element to save material usage, thus reducing costs and weight, and improve heat transfer between the temperature control element and the battery cells.

[0025] When using gap fillers, for example, air bubbles or air inclusions can occur. These can lead to safety-critical insulation defects. By incorporating an insulation film into the battery module, safety-critical insulation defects can be reduced, for example, during battery manufacturing, or reduced or eliminated, especially with regard to air inclusions in the gap filler.

[0026] The insulation film can comprise at least one flap that is folded out of the plane formed by the temperature-control surfaces. In other words, the flap can be folded upwards to the side.

[0027] This allows the insulation film with the tab to be L-shaped in cross-section. The tab can be folded up on at least one side of the insulation film. With two or more tabs, the insulation film can, for example, be U-shaped in cross-section. For example, with a rectangular insulation film, the tabs can be folded up on all four sides.

[0028] Preferably, the tab is formed circumferentially and the insulation film preferably forms a trough-shaped structure.

[0029] The fact that the insulation film comprises at least one tab makes it possible to simplify the handling of a battery module during production. For example, the at least one tab of the insulation film can make it possible to reduce the number of contact points on the battery module that are accessible to components with battery potential.

[0030] The at least one tab forms, for example, a creepage distance to prevent leakage currents. The higher the battery voltage, the longer the creepage distance must be. The at least one tab can make it possible to extend the creepage distance. In other words, it can make it possible to increase the insulation resistance, for example, of the battery module's insulation foil. Furthermore, this can make it possible to increase the safety of the battery system.

[0031] At least one tab may also be arranged between battery cells to prevent a thermally conductive element from entering spaces between battery cells.

[0032] In other words, in addition to its electrically insulating function, the insulation film can also help ensure that the thermally conductive element, such as the gap filler, remains in its assigned area and does not flow into other areas of the battery or battery module.

[0033] Accordingly, a battery for a vehicle, preferably a traction battery, is proposed, comprising at least one battery module as described above and a housing with a temperature control element for controlling the temperature of the battery cells accommodated in the at least one battery module, as well as a thermally conductive element arranged on the temperature control element. According to the invention, the insulation film is in contact with the thermally conductive element.

[0034] The battery can comprise a stacking sequence that, in the stacking direction, includes a temperature control element, a thermally conductive element, such as a gap filler, an insulation film, and the battery cells accommodated in the battery module. This can, for example, enable a smaller amount of insulation film, a smaller space requirement, and / or a lower weight, since only the temperature control surfaces of the battery cells are specifically insulated. This makes it possible, for example, to dispense with a complete enclosure for the battery cells.

[0035] The insulation film can, for example, be glued to the battery cells in the stacking order. For this purpose, the insulation film can, for example, comprise an adhesive side or a one-sided adhesive coating.

[0036] In the stacking sequence, the insulation film can be bonded to the gap filler, for example, either adhesively or by adhesive. An adhesive bond can be created either through the corresponding adhesive properties of the gap filler, through an adhesive side or an adhesive coating of the insulation film, or through a combination of both. In combination with a "cell-side" adhesive coating of the insulation film, the insulation film can therefore also have an adhesive coating on both sides.

[0037] The insulation film can extend over a battery module, a battery installation space, or the entire surface of a battery. The insulation film can be arranged on the corresponding temperature-control surfaces of the battery cells of a battery installation space. The insulation film can be arranged on the corresponding temperature-control surfaces of the battery cells across the entire surface of a battery. This makes it possible to simplify the electrical insulation of a battery module, or rather, a battery, compared to insulating each individual battery cell.

[0038] Furthermore, it can be possible to reduce production complexity and costs, for example. Furthermore, it can be possible to reduce the amount of insulation film required, since, for example, the temperature-control surfaces of the battery cells can be specifically insulated.

[0039] Furthermore, an embodiment of a battery, preferably a traction battery for vehicles, is not according to the invention.

[0040] Accordingly, a battery for a vehicle, preferably a traction battery, is disclosed, comprising at least one battery module with at least two battery cells held in a cell holder, which have temperature control surfaces that can be brought into thermally conductive contact with a temperature control element of a battery housing, and a thermally conductive element arranged between the temperature control surfaces of the battery cells and the temperature control element, as well as an insulating film arranged between the temperature control element and the thermally conductive element. According to the disclosure, the insulating film comprises at least one tab that is arranged folded out of the plane formed by the temperature control surfaces.

[0041] Preferably, the insulation film is arranged flatly on the temperature control element. More preferably, the insulation film is arranged on the temperature control element and between the temperature control element and the thermally conductive element, preferably a gap filler. In other words, a temperature control element, an insulation film, a thermally conductive element, preferably a gap pad or a gap filler, and the battery cells are provided in stacked order. The battery can preferably be provided with cylindrical battery cells. The at least one tab can, for example, be arranged folded up on a supporting structure of the battery housing.

[0042] Tabs are understood here to mean that the insulation film, for example, has an overhang over a surface to be insulated and that the overhang is folded up on the sides, for example of the battery module for the embodiment with insulation film arranged on the battery cells, or for example on the sides of a supporting structure for the embodiment in which the insulation film is arranged on the temperature control element. In other words, a tab is understood to mean that a part of the insulation film is folded over along a line or is angled with respect to the (remaining) insulation film. This can make it possible to extend a creepage distance for a creepage current across the tabs. For example, this can make it possible to increase a battery voltage or to increase an insulation resistance and reduce the probability of a safety-critical fault.

[0043] A gap filler can be applied, for example, on the temperature control element side or the cell module side, depending on the stacking sequence of the insulation film. For example, if the insulation film is arranged between the battery cells and the thermally conductive element, a gap filler can be applied on the temperature control element side. If the insulation film is arranged on the temperature control element, for example, the gap filler can be applied on the cell module side. The gap filler can be applied in a serpentine pattern, for example. Short description of the characters

[0044] Preferred further embodiments of the invention are explained in more detail in the following description of the figures. In the figures: Fig. 1 schematically shows a sectional view through a battery with a battery module, a temperature control element, a thermally conductive element and an insulation film; and Fig. 2 schematically shows a sectional view through a battery with a battery module, a temperature control element, a thermally conductive element and an insulation film in an alternative arrangement and embodiment. Detailed description of preferred embodiments

[0045] Preferred embodiments are described below with reference to the figures. Identical, similar, or equivalent elements in the different figures are provided with identical reference numerals, and a repeated description of these elements is partially omitted to avoid redundancies.

[0046] In Fig. 1 shows a very schematic sectional view through a battery 1, for example a traction battery for a vehicle, which can be used, for example, to supply an electric drive of the vehicle.

[0047] The sectional view of the battery 1 schematically shows a battery module 2 in which battery cells 5 are accommodated and held, a temperature control element 8 which serves to control the temperature of the battery cells 5 accommodated in the battery module 2, and a thermally conductive element 6 with which a thermal and mechanical connection is established between the temperature control element 8 and the battery cells 5 of the battery module 2.

[0048] The battery module 2 here comprises, for example, an upper cell holder 3 and a lower cell holder 4, as well as the battery cells 5 held in the cell holders 3, 4. The battery cells 5 are interconnected in a meaningful manner in the battery module 2, so that the battery module 2 forms an organizational unit for the battery cells 5.

[0049] In the illustrated embodiment, the battery cells 5 are cylindrical. However, other battery cells 5 can also be used.

[0050] Typically, a battery 1 comprises several battery modules 2 to provide the desired voltage and capacity. The battery modules 2 are typically housed together with other components in a battery housing 100 (not specifically shown here) to provide protection against external influences and controllable temperature control. The battery housing 100 of the battery 1 typically comprises the temperature control element 8, which can, for example, also form a base of the battery housing 100. Furthermore, a supporting structure 9 can be provided, which forms part of the battery housing 100. The battery housing 100 can, for example, provide a space sealed against environmental influences for accommodating the components of the battery 1.

[0051] The battery cells 5 have temperature control surfaces 50, which are arranged on the underside of the battery cells 5 in the figure. The temperature control surfaces 50 of the battery cells 5 face toward the temperature control element 8 and are intended to be brought into thermally conductive contact with the latter in order to achieve temperature control of the battery cells 5.

[0052] In the embodiment shown, the battery module 2 is connected to the supporting structure 9 of the battery housing 100 via schematically shown fastening means.

[0053] The thermally conductive element 6 can be designed, for example, in the form of a thermally conductive paste, for example a gap filler, or a thermally conductive mat, for example a gap pad.

[0054] An insulating film 7 is arranged between the battery cells 5 of the battery module 2 and the thermally conductive element 6. The insulating film 7 insulates the battery cells 5 from the temperature control element 8. This makes it possible to reduce or prevent a current flow between the battery cells 5 and the temperature control element 8. This is particularly important when the battery cells 5 are arranged in the battery module 2 without their own external insulation, as is usually the case in traction batteries formed from cylindrical battery cells. Providing insulation by the thermally conductive element 6 is difficult to ensure in terms of process technology, particularly when pasty materials are used. The insulating film 7 can be used to achieve electrical insulation regardless of the specific design of the thermally conductive element 6 and the assembly tolerances of the battery module 2 in the battery 1.

[0055] The insulation film 7 has tabs 10 that are folded up at the sides. The tabs 10 of the insulation film 7, for example, rest against the lower cell holder 4. The tabs 10 can additionally or alternatively rest against the battery cells 5 or be glued to them.

[0056] The insulation film 7 can have an adhesive side, which here, for example, adheres to the battery cells 5. The insulation film 7 can be attached with its adhesive side to the thermal contact surfaces of the battery cells 5. Thus, the insulation film 7 can be provided accordingly as part of the battery module 2, so that the battery module 2 can be handled together with the insulation film 7. This can, for example, simplify the assembly of the battery module 2, since the battery module 2, together with the insulation film 7 already mounted thereon, can be inserted into the battery housing 100 with the temperature control element 8 and the thermal element 6 applied thereto. The insulation film 7 is then already in the intended position and can come into contact with the thermal element 6, thus providing the required insulation.

[0057] The thermally conductive element 6 can be a gap filler. The gap filler can be applied to the temperature control element 8, and the battery module 2 with the insulation film 7 can then be placed on top and assembled. The gap filler can, for example, compensate for component tolerances and thus create reliable thermal contact between the battery cells 5 and the temperature control element 8.

[0058] The insulation film 7 is then arranged between the thermal contact surfaces of the battery cells 5 and the gap filler as a thermally conductive element 6. This makes it possible to achieve sufficient insulation resistance regardless of the properties of the gap filler used (e.g., with regard to electrical conductivity, layer thickness, air inclusions), and the technically more complex and costly insulation of each individual battery cell can be eliminated.

[0059] The tabs 10 allow the insulation film 7 to be connected more easily to the battery module 2 or to the lower cell holder 4 and / or the battery cells 5.

[0060] If the tabs 10 are formed circumferentially, then, in the case of a particularly creep-capable thermally conductive element 6, for example a particularly low-viscosity gap filler, it can be prevented that the material of the thermally conductive element 6 flows into or reaches areas of the battery module 2 where it is not intended. This also ensures that the volume of the material of the thermally conductive element 6 remains essentially constant between the battery cells 5 and the temperature control element 8 during assembly and does not flow between the battery cells 5, where it cannot exert its effect or cannot do so in the intended manner.

[0061] In other words, the tabs 10 can be used both to connect the insulation film 7 to the battery module 2 and to prevent gap filler or another thermally conductive element 6 from entering the spaces between the battery cells 5.

[0062] The tabs 10 of the insulating film 7 can also be arranged only in areas of the battery module 2 where gap filler is likely to flow between the battery cells 5—for example, at the positions of the gaps. In other words, the tabs 10 can be designed to form a shield against the gap filler.

[0063] In Fig. Figure 2 shows a schematic sectional view through a battery 1, which can be provided, for example, as a traction battery for a vehicle with an electric motor.

[0064] The schematic battery 1 is again shown as an example with a battery module 2, a temperature control element 8, a thermally conductive element 6 and an insulation film 7.

[0065] In the illustrated embodiment, the insulation film 7 is arranged directly on the temperature control element 8. The thermally conductive element 6 is thus arranged between the battery cells 5 and the insulation film 7, so that the thermally conductive element 6 comes into direct contact with the battery cells 5 of the battery module 2.

[0066] The insulation film 7 can have an adhesive side with which the insulation film 7 can be glued to the temperature control element 8.

[0067] The insulation film 7 has tabs 10 that, as shown by way of example, are folded upwards at the sides. The insulation film 7 with the tabs 10 thus rests against the temperature control element 8 and the supporting structure 9 of the battery housing 100, or is glued to these elements.

[0068] If the tabs 10 are formed circumferentially, thus forming the insulation film 7, so to speak, a trough, it is possible to prevent a creeping thermally conductive element 6, for example, a gap filler, from flowing out of its intended area. Using an electrically conductive thermally conductive element 6 also prevents electrical contact between the battery cells 5 and structures of the battery housing 100.

[0069] The battery housing 100 of the battery 1 can, for example, be lined with an insulating film 7, preferably on a surface intended as a temperature control element 8. The tabs 10 of the insulating film can be applied to the vertical sides of the battery housing, creating an electrically insulated "trough" into which, for example, a gap filler or a gap pad can be inserted. A gap filler as a thermally conductive element can, for example, be applied (in a serpentine manner) into the "trough," and then a battery module 2 can be placed in the battery housing, onto the gap filler. The battery cells 5 touch the gap filler or are at least partially enclosed by the gap filler, creating a thermal connection to the temperature control element.

[0070] The insulation foil 7 increases the creepage distance so that air inclusions in the gap filler cannot lead to a critical failure.

[0071] Where applicable, all individual features presented in the embodiments may be combined and / or exchanged without departing from the scope of the invention. List of reference symbols 1 battery 2 battery module 3 upper cell holder 4 lower cell holder 5 battery cells 6 thermally conductive element (e.g. gap filler) 7 Insulation foil 8 Tempering element 9 supporting structure 10 tabs 50 tempering surface 100 battery cases

Claims

[1] Battery (1) for a vehicle, preferably a traction battery, with at least one battery module (2), comprising at least two battery cells (5) held in a cell holder (3, 4), preferably cylindrical battery cells (5), which have tempering surfaces (50) to be brought into thermally conductive contact with a tempering element (8) of a housing (100), and a housing (100) with a tempering element (8) for tempering the battery cells (5) accommodated in the at least one battery module (2), as well as a thermally conductive element (6) arranged on the tempering element (8), characterized by that a single, electrically insulating insulation film (7) is arranged over all temperature control surfaces (50) of the battery cells (5), which provides electrical insulation between the battery cells (5) and the thermally conductive element (6), wherein the insulation film (7) is in contact with the thermally conductive element (6). [2] Battery (1) according to claim 1, characterized by that, starting from the tempering element (8), first the thermally conductive element (6), then the insulation film (7) and then the battery cells (5) are stacked on top of each other. [3] Battery (1) according to claim 1 or 2, characterized by that the thermally conductive element (6) is designed as a thermally conductive paste and / or as a thermally conductive mat. [4] Battery (1) according to one of the preceding claims, characterized by that the insulation film (7) is glued to the tempering surfaces (50) of the battery cells (5). [5] Battery (1) according to one of the preceding claims, characterized by that the insulating film (7) comprises at least one tab (10) which is arranged folded out of the plane formed by the tempering surfaces (50). [6] Battery (1) according to claim 5, characterized bythat the tab (10) is formed circumferentially and the insulating film (7) preferably forms a trough-shaped structure. [7] Battery (1) according to claim 5, characterized by that at least one tab (10) is arranged between battery cells (5) in order to prevent the entry of a thermally conductive element (6) into spaces between battery cells (5).

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