Battery module and method for operating a battery module

Abstract

A battery system (10) comprising a plurality of battery modules (11) and a cooling plate (20) connected to the battery modules (11) in a heat-conducting manner is proposed, in which the cooling plate (20) has at least two regions (22) which are separated from one another in a first direction (70) by at least one recess (30).

Description

[0001] The present invention relates to a battery module and a method for operating a battery module according to the independent claims.

[0002] Battery modules are generally known from the state of the art. Due to the increase in energy density and energy content of automotive battery cells, especially high-voltage (HV) traction batteries, the risk in the event of thermal runaway (TR) of a single battery cell or module increases. This event can spread to neighboring battery cells, in which case it is referred to as thermal propagation (TP). If this spread is interrupted in a controlled manner at a specific point, for example, limited to a specific battery cell, thus preventing complete thermal propagation of the entire system, this is referred to as a stop TP.

[0003] To avoid the problems described above, it is known from the state of the art to shield battery cells from the outside, for example, with fire-protection materials, a steel cover, or similar. Materials can also be integrated into the gaps to limit the TR event. Battery cells can also have individual cooling plates, so that there is no continuous thermal connection via a common cooling plate. However, all of these options are associated with corresponding problems. Thermal shielding from the outside is very costly and time-consuming. The same applies to inter-cell materials. Individual cooling plates for individual battery cells are not always possible within the available installation space and are therefore costly and difficult to implement.

[0004] DE 10 2017 213 276 A1 describes a battery module comprising at least one battery cell, wherein the battery cell is thermally connected to a cooling plate. A thermal compensation layer is arranged between the battery cell and the cooling plate to increase the thermal conductivity between them. The thermal compensation layer consists of a base material and a bimetallic actuator with a conversion temperature above 50°C.

[0005] DE 10 2017 009 712 A1 relates to an energy storage device for storing electrical energy for a motor vehicle. This device has two consecutive storage cells for storing the electrical energy, between which an insulating element is arranged.

[0006] DE 10 2021 111 541 A1 describes a thermomechanical fuse for mitigating heat propagation in electrochemical devices. The fuse thermally connects adjacent stacks of battery cells and is made of an electrical material.

[0007] The present invention is based on the object of further developing a battery system in such a way that the tendency for thermal propagation is reduced. In other words, the skipping of a TP event from one battery module to the next battery module is to be prevented or at least delayed.

[0008] The aforementioned object is achieved by a battery system comprising a plurality of battery modules. A battery module preferably comprises at least one battery cell, preferably a plurality of battery cells. A battery cell is primarily a traction battery, especially an HV traction battery. A battery module is equivalent to a battery stack. A battery module is essentially a detachable unit of interconnected battery cells. In particular, the battery system comprises a plurality of battery modules. The battery system is primarily an HV battery system. The battery system can preferably comprise three or more than three battery modules.

[0009] The battery system further comprises at least one cooling plate thermally connected to the battery modules. The cooling plate is primarily a common cooling plate for all battery modules of the battery system. Individual battery modules are preferably not assigned separate cooling plates. The cooling plate can simultaneously form part of the battery housing, for example, the cover or the base of the battery housing.

[0010] The cooling plate comprises at least two regions separated from each other by a recess in a first direction. The recess preferably extends in a second direction, which preferably corresponds to a longitudinal direction of the battery system, while the first direction can correspond to the width direction. The width of the recess can thus extend in the first direction. The cooling plate preferably has one fewer recess than the number of battery modules. Above all, the recess has a constant width.

[0011] The battery modules are preferably arranged spaced apart from one another in the first direction. In other words, there is a distance between adjacent battery modules. The cooling plate is thermally conductively connected to the battery modules in a third direction, which preferably corresponds to the thickness direction of the battery system, either directly or via a thermal compensation layer. The recess is then arranged in a region of the spacing between the battery modules in order to reduce a thermally conductive connection between the battery modules. In other words, the recess is arranged in the region in which the spacing between the battery modules is arranged, when projected in the thickness direction of the battery module. The recess preferably extends over the entire thickness of the cooling plate, so that no cooling plate is present in the region of the recess.

[0012] The cooling plate is preferably made of metal. The expansion preferably does not extend over the entire length of the cooling plate, but essentially over the entire length of the battery modules, preferably over at least 70% or at least 80% or at least 90% of the length of the battery modules. In particular, the battery system comprises a collector / distributor region at both longitudinal ends, in which the cooling water from the cooling plate can collect. Appropriate collector and / or distributor structures can be present here to facilitate this. In these regions, preferably no recesses are provided in the cooling plate. Preferably, the recesses can extend continuously from one end region, in which a collector / distributor region is located, to the other collector / distributor region. At least one web for establishing a heat-conducting connection can be arranged between the two regions.Thus, the recesses in the first direction can be bridged, or in other words, interrupted, by at least one web. The heat-conducting connection between adjacent battery modules in the first direction is thus reduced to the webs.

[0013] In other words, the recess can thus be divided by the at least one web into sub-regions that are separated by the web. The battery system can preferably comprise at least three regions. Two or three or more than three webs can preferably be arranged between adjacent regions. The width of a web extends primarily in the second direction, while its length extends in the first direction. The at least one web preferably has a constant width. The at least one web can have a width of less than 50%, preferably less than 30%, preferably less than 10%, of a width of the recess.

[0014] The at least one web is preferably designed to change its position and / or shape above a limit temperature, such that the heat-conducting connection between at least two regions of the cooling plate is at least reduced or interrupted. The limit temperature is in particular a temperature above 45°C, preferably above 50°C, most preferably above 60°C. Heating of the web occurs when a battery module is heated, which experiences a thermal transition (TR). As a result, the cooling plate directly above it heats up, and thus also the web that connects this region of the cooling plate to an adjacent region. The battery module, which has heated up above the limit temperature, and adjacent battery modules are thermally connected to one another via the cooling plate and, if applicable, a thermal compensation material.Thus, heat flow via the cooling plate primarily leads to adjacent areas. However, since the cooling plate is interrupted in the primary direction by the recess, the heat flow leads via the at least one web. To prevent thermal propagation, the at least one web, preferably all webs, change their position and / or shape, so that the heat-conducting connection via them is reduced or interrupted.

[0015] The thermally conductive connection can preferably comprise an adhesive bond, wherein the adhesive bond separates above the threshold temperature. In other words, an adhesive bond can be present in the region of the web, for example, directly at the web or in a connection area to a region of the cooling plate. The adhesive used is designed such that it separates above the threshold temperature, thus reducing and / or preventing the thermally conductive connection. In other words, the bridging of the regions via the web is reduced or eliminated, and the thermally conductive connection is interrupted.

[0016] The same can apply to a wax bond. For example, the thermally conductive connection in the area of the web may include a wax bond, with the wax bond breaking above the threshold temperature. Directly at the web or at a connecting area of the web to the cooling plate areas, which are connected via the web, a wax bond may be present that melts above the threshold temperature, thus reducing the thermally conductive connection.

[0017] Furthermore, the thermally conductive connection in the region of the web, for example, directly at the web or in a connection area to a region of the cooling plate, can comprise a bimetallic element, wherein the bimetallic element is designed to deform upon an increase above the limit temperature. This can, for example, deform and / or even destroy the web in such a way that the thermally conductive connection is severed. In other words, the web can break open.

[0018] Furthermore, a predetermined breaking point can be provided in the area of the web, either directly at the web or in a connecting area, where the connection is to be interrupted. This can significantly simplify interrupting the heat flow through the web.

[0019] In a further aspect, the invention relates to a method for operating a battery module which is designed as described above, wherein the method comprises a reduction of the heat-conducting connection between two adjacent battery modules, preferably by providing a web between the regions and a reduction of the heat-conducting connection via the web between the battery modules above a limit temperature.

[0020] They show in purely schematic representation Fig. 1: a top view of a battery system, Fig. 2: another top view of the battery system of the Fig. 1, Fig. 3: a cross-section of part of the battery system of the Fig. 1 and Fig. 2; and Fig. 4: use of a battery system according to the Fig. 1 to 3.

[0021] In Fig. 1 shows a battery system 10 with a plurality of battery modules 11. A first direction 70 and a second direction 71 are shown.

[0022] The right battery module 11 has heated up and is thus shown as a heated battery module 11a that is above the limit temperature. The battery system 10 includes a cooling plate 20 with cooling water. Fig. 1, the cooling plate 20 is shown transparently so that the underlying battery modules 11 and the compensation layer 80 arranged between them can be seen.

[0023] The cooling plate 20 has at least two regions 22, which are separated from each other by at least one recess 30 in the first direction 70. In other words, the recess 30 lies between the two regions 22 in the first direction and thus separates them from each other.

[0024] In Fig. 1 shows in detail a first region 23, a second region 24, and a third region 25, with a recess 30 provided between the first region 23 and the second region 24 and between the second region 24 and the third region 25. The recesses 30 extend with their length in the second direction 71 and with their width 31 in the first direction 71.

[0025] The regions 22 are connected to one another via webs 40. The recess 30 is thus bridged in the regions of the webs 40. In other words, a heat-conducting connection in the first direction 70 exists between the adjacent battery modules due to the webs 40. The corresponding heat flow 95 via the webs 40 between the battery modules 11 is shown.

[0026] In Fig. 1 shows three webs 40, each having a width 41. In Fig. 1, a collector / distributor region 50 is provided in each of the upper and lower regions of the battery system 10, in which no recess 30 of the cooling plate 20, which also extends in this region, is provided.

[0027] In Fig. 2 is another plan view of the battery system 10 according to Fig. 1. It shows how the heat-conducting connection, i.e., the heat flow 95, between the heated battery module 11a on the right and the adjacent battery module 11 is reduced or interrupted. Specifically, the heat flow 95 in the primary direction 70 is already interrupted by the recess 30 and reduced to the webs 40. These heat-conducting paths are now broken due to the temperature increase of the heated battery module 11a, which is represented by the crosses. This can be achieved by the heat-conducting connection comprising an adhesive bond; in other words, the web or a connection region of the web can comprise an adhesive bond that can detach above a threshold temperature. The same can be the case with a wax bond.Furthermore, the thermally conductive connection may comprise a bimetallic element, for example in the region of the web or in the region of the web, which deforms and thus reduces or prevents the thermally conductive connection via the web.

[0028] In Fig. 3 shows a cross-section, i.e., a section along the first direction 70, in which two battery modules 11 can be seen. The cross-section is arranged in the region of a recess 30 in the cooling plate 20, so that the interruption of a heat flow in the first direction 70 between the battery modules 11 can be clearly seen. Furthermore, the third direction 72 can be seen.

[0029] In Fig.Figure 4 shows a process diagram of a method 100 for operating a battery system 10, which comprises a reduction 101 of the thermally conductive connection between two adjacent battery modules 11. Specifically, at least one recess is provided 102 between two regions of the cooling plate. Furthermore, a web is provided 103 that bridges the recess in the first direction. Above a threshold temperature, the thermally conductive connection is reduced 104 via a web between the battery modules. This is achieved, for example, by providing an adhesive and / or wax connection and / or a bimetallic element that reduces and / or interrupts the thermally conductive connection. List of reference symbols 10 Battery system 11 Battery module 11a Battery module above the limit temperature 20 cooling plate 22 Area 23 first area 24 second area 25 third area 30 recess 31 Width of the recess 40 bridge 41 Width of the bridge 50 collector / distribution area 60 heat flow 70 first direction 71 second direction 72 third direction 80 thermal compensation layer 100 Methods for Operating a Battery System 101 Reduction of the heat-conducting connection between two adjacent battery modules 102 Providing at least one recess between two areas of the cooling plate 103 Provision of a bridge between the areas 104 Reduction of the heat-conducting connection via a bridge between the battery modules QUOTES CONTAINED IN THE DESCRIPTION

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

[0000] DE 10 2017 213 276 A1

[0004] DE 10 2017 009 712 A1

[0005] DE 10 2021 111 541 A1

[0006]

Claims

[1] Battery system (10) comprising several battery modules (11) and a cooling plate (20) thermally connected to the battery modules (11), characterized by , that the cooling plate (20) has at least two regions (22) which are separated from one another in a first direction (70) by at least one recess (30). [2] Battery system (10) according to claim 1, characterized by that at least one web (40) is arranged between the regions (22) to bridge the recess (30) and to produce a heat-conducting connection between the two regions (22) in the first direction (70). [3] Battery system (10) according to claim 2, characterized by that the at least one web (40) has a width (41) of less than 50% of a width (31) of the recess (30). [4] Battery system (10) according to claim 2 or 3, characterized bythat two or three webs (40) are arranged between the two areas (22) of the cooling plate (20). [5] Battery system (10) according to one of the preceding claims, characterized by , that the cooling plate (20) comprises at least three areas (22), wherein adjacent regions (22) are interrupted in the first direction (70) by a recess (30). [6] Battery system (10) according to one of the preceding claims, characterized by that the at least one web (40) is designed to change its position and / or shape above a limit temperature, so that the heat-conducting connection between regions (22) of the cooling plate (20) connected via these webs is at least reduced. [7] Battery system (10) according to claim 6, characterized by , that the heat-conducting connection comprises an adhesive connection, The adhesive bond separates above the limit temperature. [8] Battery system (10) according to claim 6 or 7, characterized by , that the heat-conducting compound comprises a wax compound, whereby the wax compound separates above the limit temperature. [9] Battery system (10) according to one of claims 6 to 8, characterized by , that the heat-conducting connection comprises a bimetallic element, wherein the bimetallic element is designed to deform upon an increase above the limit temperature such that the heat-conducting connection is reduced or separated. [10] Method (100) for operating a battery module (10) according to one of claims 1 to 9, characterized by that the method (100) comprises providing (102) a recess (30) between two regions (22) of a cooling plate (20), wherein the recess (30) separates the regions (22) in the first direction (70).

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