Cell contacting device for a high-voltage storage module

Abstract

The invention relates to a cell contacting device (30) for a high-voltage storage module (10), comprising at least a first connection device (31) which is configured to electrically connect at least two battery cells (20) of a cell pack (12) of the high-voltage storage module (10) in parallel, and at least a second connection device (32) which is configured to electrically connect at least two battery cells (20) of the cell pack (12) of the high-voltage storage module (10) in series.

Description

[0001] The invention relates to a cell contacting device for a high-voltage storage module, comprising at least one first connecting device configured to electrically connect battery cells of a cell pack of the high-voltage storage module in parallel, and at least one second connecting device configured to electrically connect battery cells of the cell pack of the high-voltage storage module in series. Furthermore, the invention relates to a high-voltage storage module and a motor vehicle.

[0002] High-voltage storage units, 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 unit typically comprises battery cells or round battery cells connected in parallel and series, which are arranged in packs. Electrically conductive cell connectors or cell contacting devices can be used to interconnect the battery cells; these can, for example, be electrically connected to the end-face contacts of several battery cells in the pack.

[0003] For example, external mechanical damage, internal damage due to crushing or compression, as well as overcharging and / or thermal overheating, can trigger a self-reinforcing, energy-producing process in a battery cell, also known as thermal runaway. Such thermal runaway can lead to the battery cell bursting and / or burning, as well as to a further reaction in the form of thermal propagation. The thermal runaway event can then spread to neighboring battery cells, resulting in a chain reaction. Therefore, preventing thermal propagation of a thermal event from battery cell to battery cell represents an important safety challenge.

[0004] Against this background, it is an object of the invention to improve a cell contacting device for a high-voltage storage module or a high-voltage storage device. In particular, the cell contacting device is to be improved such that the risk of propagation or expansion of a thermal event can be reduced.

[0005] This object is achieved by a cell contacting device for a high-voltage storage module having the features of claim 1, a high-voltage storage module having the features of claim 9 and a motor vehicle having the features of claim 10. The dependent claims relate to advantageous developments of the invention.

[0006] According to a first aspect, a cell contacting device for a high-voltage storage module is specified, comprising at least one first connecting device which is configured to electrically connect battery cells of a cell pack of the high-voltage storage module in parallel, and at least one second connecting device which is configured to electrically connect battery cells of the cell pack of the high-voltage storage module in series, wherein the at least one first connecting device has a higher electrical resistance than the at least one second connecting device.

[0007] By increasing the electrical resistance in the parallel connection of the battery cells of the high-voltage storage module, which can be provided or is available using the cell contacting device, the fault current flowing in the event of a thermal runaway or fault in the parallel connection can be limited. This allows the effects or consequences caused by a defective battery cell, which typically represents a low resistance in the parallel connection, to be limited, thus avoiding or preventing the propagation of the thermal runaway to a neighboring battery cell.

[0008] According to a further aspect, a high-voltage storage module, in particular for a vehicle battery, is proposed, comprising a plurality of battery cells arranged in a cell pack, wherein at least two battery cells are electrically connected by means of a cell contacting device described herein.

[0009] A high-voltage storage module can be part of a high-voltage storage device or a vehicle battery, or it can itself form the high-voltage storage device or the vehicle battery. The high-voltage storage module is, in particular, an energy storage device or a drive accumulator for a motor vehicle, which has multiple battery cells. Cylindrical battery cells are used in particular, which can be provided, for example, in hexagonal pack arrangements. In this case, a battery cell has a circular cell cross-section and a longitudinal axis arranged perpendicular to it, and is delimited in the longitudinal direction by two end faces, wherein the end faces are connected by a cell casing or a casing surface.

[0010] Of course, battery cells with other cross-sections, such as rectangular, hexagonal, or prismatic cross-sections, can also be used. When installed in a motor vehicle, the vehicle battery and / or the battery cells can be arranged such that the longitudinal axes of the battery cells are parallel to the vehicle's vertical axis.

[0011] By means of the cell contacting device, an electrical parallel and series connection of these battery cells in a cell assembly can be enabled. For this purpose, the cell contacting device has at least one first connecting device and at least one second connecting device, which are each designed to enable an electrical connection between the battery cells. To connect the battery cells in parallel by means of the at least one first connecting device, for example, first poles and / or second poles of a respective battery cell can be connected to one another so that the charging capacity of the battery cells can be added together. For the serial connection, a first pole of one battery cell is electrically connected to a second pole of another battery cell by means of at least one second connecting device, so that in particular all battery cells are electrically connected in series.The cell contacting device can be formed as a single piece to electrically connect a plurality of battery cells, or it can have (a plurality of) individual first and second connecting devices that are electrically and / or mechanically connectable or connected to one another. For example, the cell contacting device can be formed as a stamped or lasered cell contacting plate. The connecting devices can be arranged on the end faces of the battery cells of the high-voltage storage module or the vehicle battery and can be formed, in particular, as electrically conductive tracks, strips, or plates that are configured to connect positive and / or negative contacts of battery cells, in particular across cell rows.

[0012] The invention is based in particular on the idea of ​​making a parallel connection of battery cells in a cell assembly more robust, particularly electrically. This is based, among other things, on the realization that limiting the current flowing through the serial path would increase the internal resistance of the high-voltage storage module, which could result in limitations in terms of performance and thermal resilience for the high-voltage storage module. In order to increase the robustness of a parallel connection of several battery cells against short circuits, it is now proposed to provide a higher electrical resistance for the connection device for the parallel connection than for the serial connection device.In some embodiments, an electrical resistance that is at least two orders of magnitude greater than that of the second connection device for connecting the battery cells in series can be provided for the first connection device for parallel connection. Assuming that a short-circuit current I of ~10 A can be sustained over a long period, an exemplary resistance of R = 0.42 ohms can result at a cell voltage U = 4.2 V, which can be divided between two first connection devices. This can result in a resistance of R = 0.21 ohms for the two first connection devices.

[0013] This can reduce fault currents in the event of a thermal runaway of a battery cell, which could lead to thermal propagation of neighboring battery cells. Furthermore, the proposed solution eliminates the need for fuses to prevent thermal propagation in cell contact systems, thus reducing manufacturing effort and / or enabling cost reduction.

[0014] In one embodiment, the at least one first connecting device has a higher melting point than the at least one second connecting device. This allows an increased fault current to flow in the first connecting device in the event of a fault or thermal runaway without resulting in damage to the cell contacting device. This can increase the thermal resilience of the cell contacting device and / or the high-voltage storage module, while simultaneously preventing the propagation of a thermal event.

[0015] In one embodiment, the at least one first connecting device comprises a first material that is different from a second material of the at least one second connecting device. In this case, the at least one first and at least one second connecting device can be designed separately and can be electrically contacted or can be contacted via mechanical or electrical connections. In other embodiments, a particularly one-piece design of the cell contacting device can be provided by suitable material or joining connections. The first and / or the second material is in particular at least one metal in order to be able to provide the respectively desired electrical conductivity value or electrical resistance.

[0016] In one embodiment, the at least one first connecting device comprises steel. The first connecting device can, for example, comprise a steel alloy or be made of a steel alloy that is optimized or selected, in particular, for the desired or predetermined electrical conductivity. This allows an electrical resistance to be selected for the at least one first connecting device that is approximately two orders of magnitude greater than the electrical resistance of the at least one second connecting device for serially connecting the battery cells.

[0017] In one embodiment, the at least one second connecting device comprises tungsten. By using tungsten as a component or material of the second connecting device, the electrical resistance can be selected or set to a desired level relative to the second connecting device, such that the electrical resistance of the at least one first connecting device limits a fault current and / or allows only a throttled fault current to neighboring cells of a defective cell.

[0018] In one embodiment, the at least one second connecting device comprises or is made of aluminum. This allows the serial connecting devices to have good electrical conductivity, thereby meeting requirements for current-carrying capacity in the serial direction. This makes it possible to provide a cost-effective solution for serially connecting the battery cells. Furthermore, aluminum can provide a practical starting point for the design of the electrical resistance of the at least one first connecting device, in particular having an electrical resistance that is, for example, two orders of magnitude higher.

[0019] In one embodiment, the at least one first connecting device has a smaller cross-section than the at least one second connecting device. In particular, the different electrical resistance is based on a different geometry of the at least one first connecting device and the at least one second connecting device. In this case, the at least one first connecting device for electrical parallel connection can be narrower, flatter, and / or longer than the at least one second connecting device, in particular in a connection region between two contact points of battery cells to be connected or connected. The electrical resistance can be increased by such a geometric configuration, as a result of which possible short-circuit currents in the region of the connecting device can be throttled.This ensures that such short-circuit currents are outside a safety-critical range, which means that neighboring battery cells are subjected to less stress in the event of a fault.

[0020] In one embodiment, the at least one first connecting device and at least one second connecting device comprise the same material, wherein, in particular to provide a higher electrical resistance, the at least one first connecting device and the at least one second connecting device, as described above, may have a different geometry or a different cross-section and / or a different length.

[0021] According to a further aspect, a motor vehicle is proposed which has a high-voltage storage module or a high-voltage storage device described herein, or whose vehicle battery or high-voltage storage device has at least one cell contacting device of the type described herein. The effects and advantages described above and below can be utilized by such a motor vehicle to increase overall safety, particularly in the event of a battery failure, in particular by preventing the propagation of a thermal event or a thermal runaway, particularly of several adjacent cells.

[0022] Further advantages and possible applications of the invention will become apparent from the following description in conjunction with the figures. Fig. 1 shows a schematic view of a first embodiment of a high-voltage storage module with a cell contacting device according to one embodiment of the present disclosure.

[0023] Fig. 1 shows a first embodiment of a high-voltage storage module 10 for a motor vehicle with a cell pack 12 of battery cells 20, which are electrically connected by means of a cell contacting device 30, in a schematic plan view.

[0024] The high-voltage storage module 10 or the high-voltage storage device has a plurality of battery cells 20, wherein the cylindrical battery cells 20 here are arranged in a substantially hexagonal cell pack 12. In the illustrated embodiment, three battery cells 30 are arranged in a cell row, and the battery cells 20 of the cell pack 12 are connected in parallel and serially at their end faces by means of the cell contacting device 30. The cell contacting device 30 has connection sections 33 that are configured to be connected to electrical components, such as a work machine.

[0025] For this purpose, the cell contacting device 30 has first connecting devices 31, which are configured to electrically connect at least two battery cells 20 in parallel, and second connecting devices 32, which are configured to electrically connect at least two battery cells 20 in series. The first connecting devices 31 have a higher electrical resistance than the second connecting devices 32. In addition, the first connecting devices 31 have a higher melting point than the second connecting devices 32. As a result, in the event of a thermal event or thermal runaway of a battery cell 20, a fault current flowing in the parallel connection can be limited, thereby limiting the effects or impacts of a single defective battery cell. The risk of propagation of the thermal runaway to neighboring, electrically connected battery cells 20 can thus be avoided or even prevented.

[0026] In order to increase the electrical resistance of the first connecting devices 31 compared to the electrical resistance of the second connecting devices 32, in particular by two orders of magnitude, the first connecting devices 31 can comprise a first material that differs from a second material of the second connecting devices 32. For example, the first connecting devices 31 can comprise or be made of steel and / or tungsten, and the second connecting devices 32 can comprise or be made of aluminum.

[0027] In addition, the first connecting devices 31 and the second connecting devices 32 can each have different geometries, in particular different cross sections, so that the first connecting devices 31 have a higher electrical resistance than the second connecting devices 32. In this case, the first connecting devices 31 can in particular be narrower, flatter and / or longer than the second connecting devices 32, in particular even if the connecting devices 31, 32 have the same material in some embodiments.

Claims

[1] Cell contacting device (30) for a high-voltage storage module (10), comprising at least one first connecting device (31) which is designed to electrically connect at least two battery cells (20) of a cell pack (12) of the high-voltage storage module (10) in parallel, and at least one second connecting device (32) which is designed to electrically connect at least two battery cells (20) of the cell pack (12) of the high-voltage storage module (10) in series, wherein the at least one first connecting device (31) has a higher electrical resistance than the at least one second connecting device (32). [2] Cell contacting device (30) according to the preceding claim, wherein the at least one first connecting device (31) has a higher melting point than the at least one second connecting device (32). [3] Cell contacting device (30) according to one of the preceding claims, wherein at least one first connecting device (31) has a first material different from a second material of the at least one second connecting device (32). [4] Cell contacting device (30) according to one of the preceding claims, which comprises at least one first connecting device (31) made of steel. [5] Cell contacting device (30) according to one of the preceding claims, which comprises at least one first connecting device (31) made of tungsten. [6] Cell contacting device (30) according to one of the preceding claims, which comprises at least one second connecting device (32) made of aluminum. [7] Cell contacting device (30) according to one of the preceding claims, wherein the at least one first connecting device (31) has a smaller cross-section than the at least one second connecting device (32). [8] Cell contacting device (30) according to the preceding claim, wherein the at least one first connecting device (31) and the at least one second connecting device (31) comprise the same material. [9] High-voltage storage module (10) for a motor vehicle, comprising a plurality of battery cells (20) arranged in a cell pack (1)2, wherein at least two of the battery cells (20) are electrically connected by means of at least one cell contacting device (30) according to one of the preceding claims. [10] Motor vehicle, comprising at least one high-voltage storage module (10) according to claim 9 and / or at least one cell contacting device (30) according to one of claims 1 to 8.

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