Holding device for battery cells

Abstract

The present invention relates to a holding device for battery cells used to form a high-voltage storage module that can be used in electric vehicles. The battery cells in a parallel arrangement are provided with a minimally thin thermal insulation layer and are thus wrapped and placed in direct contact with one another in a self-sustaining manner. The gaps between the battery cells provided with the insulation layer and thus wrapped and placed in direct contact are filled with a thermally conductive filler. The insulation layer and the filler minimize the cell spacing to 0.05 to 0.4 mm. The thermally conductive filler can also have a high electrical conductivity, so that, in addition to heat transfer, contact between the anodes in the parallel arrangement can also be established when the filler is also wrapped around the anodes. The present invention also relates to a vehicle having a high-voltage storage device, which has the holding device described.

Description

Technical Field

[0001] The invention relates to a holding device for battery cells which are assembled in multiple quantities to form a battery module of a high-voltage battery, in particular for electric vehicles or hybrid vehicles. Background Art

[0002] In order to provide electrical energy, storage batteries are known, which are also called batteries or accumulators. In order to supply the electric drive of the vehicle, relatively high voltage, for example 400V, of electrical energy is required, and the storage batteries used for this purpose are also called high-voltage storage or power batteries. Such high-voltage storage is generally not constructed as a single block nowadays, but is modularly composed of multiple battery cells. This increases the freedom of design and allows the use of relatively inexpensive standard cells that can be manufactured as mass-produced products instead of specific customizations. The number of battery cells used is directly related to the driving range of the electric vehicle or hybrid vehicle. In practice, as battery cells for high-voltage storage, for example, round cells or prismatic battery cells are used.

[0003] Furthermore, high-voltage storage devices are often installed in the area of a passenger compartment or a luggage compartment of a vehicle and disadvantageously occupy space.

[0004] There is therefore a need to find a solution for installing high-voltage storage devices in such a way that passenger comfort and loading space are restricted as little as possible. Therefore, the goal is to maximize the use of space that would otherwise be unused for installing battery cells and thereby achieve a high packing density of the battery cells. Such a holding device is known, for example, from DE 10 2016 206 463 A1, which comprises, in particular, a plastic holder that is inserted into the gaps between the battery cells.

[0005] Furthermore, in the event of a battery cell failure, the first battery cell may experience thermal breakdown (so-called "thermal runaway") and rupture due to a significant temperature increase. During this process, hot gases and soot particles are emitted. These gases and particles are distributed throughout the module and can heat adjacent cells. If the temperature rises above a critical threshold during this heat transfer, other cells may also experience thermal breakdown (heat propagation).

[0006] Another problem is the side cracking of cells during thermal breakdown, also known as "side cracking." During this process, a significant amount of heat energy can be transferred to adjacent cells in a very short period of time. Controlling the heat transfer caused by "side cracking" is particularly difficult when the cells are insulated with air. Summary of the Invention

[0007] The object of the present invention is to provide a holding device for a single battery cell which is improved with respect to the aforementioned temperature problems.

[0008] The present invention relates to a holding device for battery cells used to form a high-voltage storage module that can be used in electric vehicles. The battery cells are provided with a minimally thin thermal insulation layer in a parallel arrangement (i.e., an arrangement connected in parallel) and are thus wrapped in a self-sustaining manner and placed in direct contact with one another. The individual battery cells in the parallel arrangement can be provided with a thermal insulation layer, and the gaps between the battery cells provided with the insulation layer and thus wrapped in contact with one another are filled with a thermally conductive filler. The insulation layer and filler minimize the cell spacing to 0.05 to 0.4 mm.

[0009] In a further development of the invention, the interspaces between the battery cells provided with thermal insulation layers and placed in contact with one another in this manner are filled with a thermally conductive potting compound, with which the anodes are also surrounded.

[0010] The potting compound preferably simultaneously forms an adhesive connection between the battery cells and the cooling plate.

[0011] In another embodiment of the present invention, the filler has a high thermal conductivity, which can be between the thermal conductivity of air and the thermal conductivity of the battery housing. Preferably, a thermal conductivity of at least 1 W / mK can be provided.

[0012] Preferably, the heat-conducting potting compound additionally has a high electrical conductivity and, in addition to heat transfer, also establishes contact between the anodes in the parallel arrangement if the anodes are also encased in the potting compound.

[0013] The present invention is based on the following considerations:

[0014] Typically, efforts are made to prevent so-called heat propagation within battery modules constructed from multiple battery cells. This is a measure designed to reduce temperature transfer between the battery cells. This is intended to reduce the likelihood that a thermally broken battery cell will trigger thermal breakdown in its neighboring cells through heat transfer. This comes at the expense of packing density.

[0015] Therefore, according to the present invention, in order to increase the packing density, the battery cells are arranged as close together as possible so that temperature exchange is intentionally allowed. However, instead of thermal insulation, an improved and most uniform temperature transfer is ensured.

[0016] Therefore, according to the present invention, a minimal thermal insulation layer is applied around the battery cells. This layer results in relatively small spacings between the battery cells (approximately between 0.05 and 4 mm), allowing a certain degree of "thermal contact," i.e., thermal temperature transfer to adjacent cells. This minimal insulation layer can be achieved, for example, by shrink-fitting a hose, wrapping film, or wrapping with tape.

[0017] In high-voltage batteries commonly found in the automotive sector, cell spacings of approximately 1 to 3 mm have been typical, particularly between round cells. According to the present invention, the cell spacing is minimized to approximately 0.05 to 0.4 mm. This dense packing density eliminates the need for conventional supports or brackets for the individual battery cells in a module, as the cells are held together. Cell alignment is also unnecessary, as a natural arrangement ("pack") is created, particularly in a hexagonal configuration.

[0018] The battery cells thus "packed" are preferably connected to the cooling plate via a thermally conductive compound (e.g., an adhesive or resin), wherein the thermally conductive compound is at least partially pressed into the gaps between the battery cells in order to also secure the battery cells to one another. The compound is preferably both thermally and electrically conductive.

[0019] In a particularly preferred embodiment, the following features are commonly adopted:

[0020] The individual cells are provided with a very thin thermal insulation layer (0.05-0.4 mm) and then—wrapped in this manner—placed in direct contact with one another. The spacing between the individual cells is thus created by the thin insulation layer.

[0021] - In order to prevent thermal breakdown and especially lateral breakdown (thermal runaway or lateral rupture), the gaps between the cells that are thus wrapped and then "packed" as tightly as possible are filled with a thermally conductive filler (such as filling foam, adhesive, resin, etc.). The higher the thermal conductivity of the filler, the better the heat transfer between the cells. When the thermal conductivity is similar to that of a metal battery case, the heat is dissipated particularly evenly to adjacent cells. Therefore, propagation can be suppressed. It is particularly important to achieve as uniform heating of the cells as possible. Broad heat transfer to adjacent cells should be achieved in a larger surrounding environment, not just at the points where the cell cases are in physical contact.

[0022] The thermally conductive filler should preferably also have high electrical conductivity (e.g., graphite, carbon, metal particles, or metal filaments). The individual cells are packaged and bonded only in the parallel assembly (parallel connection). Only each parallel assembly needs to be electrically insulated. The electrically conductive filler thus does not hinder and can also serve to connect the individual anodes in the parallel assembly.

[0023] - Alternatively (also as an independent concept according to the invention), instead of an insulating layer around each cell, only one insulating layer can be provided around the parallel arrangement of cells, whereby the cells within the parallel arrangement are in electrical contact via the cell sheath (at anode potential in the case of a steel sheath), in such a way that in this case the gaps between the individual cells of the parallel arrangement are also filled with a thermally and electrically conductive filler. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The present invention will be described below with reference to the accompanying drawings with the aid of preferred embodiments. The description in the accompanying drawings should be understood as being purely schematic. The accompanying drawings are as follows:

[0025] Figure 1 Schematic diagram of a top view and a cross-sectional view of battery cells, which are provided with a thin thermal insulation layer, are tightly packed, and their interstices are filled with a filler;

[0026] Figure 2 Show the mode of action of two different fillers with different thermal conductivities; and

[0027] Figure 3 A plan view of a single battery cell is shown, wherein the anode is contact-connected via an electrically and thermally conductive potting compound. DETAILED DESCRIPTION

[0028] exist Figure 1 Schematically shown are battery cells 1 which are provided with a very thin thermal insulation layer of approximately 0.05-0.4 mm (see thin white ring around the black battery housing) and are thus wrapped in direct contact with one another. The spacing 5 between the individual cells 1 is produced by the thin insulation layer.

[0029] To prevent thermal breakdown and especially lateral breakdown, the gaps between the cells 1 that are thus wrapped and then "packed" as tightly as possible are filled with a thermally conductive filler 2 (e.g., filling foam, adhesive, resin, etc.). At the same time, the cells 1 are fixed to the cooling plate 4 by the preferably adhesive filler 2.

[0030] The higher the thermal conductivity of filler 2, the better the heat transfer between cells. When the thermal conductivity is similar to that of the battery housing, heat is dissipated particularly evenly to adjacent cells, thus suppressing the spread of heat.

[0031] exist Figure 2 The conductivity of the two different fillers 2a and 2b is described by small short arrows. Figure 2 There is filler 2a on the left, which has a lower thermal conductivity than that on the Figure 2 Thermal conductivity of filler 2b on the right.

[0032] The heat-conducting filler 2 (2b) should preferably also have a high electrical conductivity. Figure 3 To explain. The cells 1 are packaged and bonded only in the parallel arrangement (parallel connection). The conductive filler 2 (2b) thus creates the contact-connection 3 of the anodes in the parallel arrangement. In the first alternative, the individual cells of the parallel arrangement, or in the second alternative, only the parallel arrangement as a whole (without a cell-specific insulation layer), can be provided with a thermal insulation layer.

[0033] In summary, the present invention relates to a holding device for battery cells 1 for forming a high-voltage storage module that can be used in electric vehicles. The battery cells 1 are provided with a minimally thin thermal insulation layer in a parallel arrangement (i.e., connected in parallel) and are thus encased in direct, self-sustaining contact with one another. Preferably, the gaps between the insulating battery cells 1, which are thus encased in contact with one another, are filled with a thermally conductive filler 2. The thermally conductive filler 2 can also have a high electrical conductivity and, in addition to heat transfer, can thus also establish contact between the individual anodes in the parallel arrangement if these are also encased in the filler 2.

Claims

1. A holding device for a battery cell (1) for forming a high-voltage storage module that can be used for an electric vehicle, characterized in that Battery cells (1) in a parallel assembly are provided with a minimally thin thermal insulation layer and are wrapped in this manner so as to be placed in direct contact with each other in a self-sustaining manner. Each cell in the parallel assembly is provided with the insulation layer. The gaps between the battery cells (1) provided with the insulation layer and wrapped in this manner so as to be placed in direct contact with each other are filled with a thermally conductive filler (2, 2a, 2b). The cell spacing is minimized to 0.05 to 0.4 mm by the insulation layer and the filler.

2. The holding device according to claim 1, characterized in that The compounding material (2, 2a, 2b) simultaneously forms an adhesive connection between the battery cell (1) and the cooling plate (4).

3. The holding device according to claim 1 or 2, characterized in that The filler material (2, 2a, 2b) has a high thermal conductivity which is at least approximately equal to the thermal conductivity of the battery housing.

4. The holding device according to claim 1 or 2, characterized in that The filler has a thermal conductivity of at least 1 W / mK.

5. The holding device according to claim 1 or 2, characterized in that The heat-conducting filler (2, 2a, 2b) also has a high electrical conductivity and, in addition to heat transfer, also creates contact leads (3) for the anodes in the parallel arrangement, wherein the filler (2, 2a, 2b) also surrounds the anodes.

6. The holding device according to claim 5, characterized in that The filler is graphite, carbon, metal particles or metal wires.

7. The holding device according to claim 1 or 2, characterized in that The battery cell is a circular cell.

8. A vehicle having a high-voltage accumulator with a holding device for a battery cell (1) according to any one of claims 1 to 7.

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