Battery module for a high-voltage battery

Abstract

The invention relates to a battery module (100) for a high-voltage battery of an electric vehicle, comprising a plurality of battery cells (10) which are densely packed and arranged adjacent to one another in a common module housing (40). Each battery cell (10) has a bursting element (14) on a first end face (12) which opens in a controlled manner at a predetermined pressure. A thermal break layer (20) is arranged on the first end face (12) of the battery cells (10), and the thermal break layer (20) seals tightly against the side walls (42) of the module housing (40).

Description

[0001] The invention relates to a battery module for a high-voltage battery of an electrically powered vehicle.

[0002] The operational reliability of high-voltage batteries, especially in electric vehicles, is a crucial design criterion. Since increasingly stringent requirements are placed on such batteries, for example regarding maximum energy density and capacity, as well as relatively high charging and discharging capacities, their design presents significant challenges.

[0003] To avoid so-called thermal propagation in battery modules during thermal events, i.e., the spread of the thermal event by hot gases from one battery cell to neighboring battery cells, for example in an accident or fire, significant effort is expended in conventional batteries, which can be associated with correspondingly high costs, high installation space requirements and high weight.

[0004] DE 10 2020 127 589 A1 describes a battery device comprising a housing, several cell modules housed therein, and a partition element. The partition element divides the housing into several cell receiving areas, each larger than one of the cell modules, and in each of these areas at least one cell module is arranged, leaving an empty deformation space in each cell receiving area next to the at least one cell module. The partition element is designed as a fastening element by means of which the cell modules are held in the cell receiving areas adjacent to the respective partition element.

[0005] One objective of the invention is to create an improved battery module for a high-voltage battery of an electrically powered vehicle with high operational reliability.

[0006] The aforementioned problem is solved using the features of an independent claim.

[0007] Favorable embodiments and advantages of the invention will become apparent from the further claims, the description and the drawing.

[0008] According to one aspect of the invention, a battery module for a high-voltage battery of an electric vehicle is proposed, comprising a plurality of battery cells which are densely packed and arranged adjacent to one another in a common module housing. Each battery cell has a rupture element on a first end face, which opens in a controlled manner at a predetermined pressure. A thermal break layer is arranged on the first end face of the battery cells, and this thermal break layer seals tightly against the side walls of the module housing.

[0009] In the proposed battery module, thermal propagation within the cell block or battery module can be prevented by the thermal break layer in the event of a thermal event where the rupture elements of one or more battery cells open. Heat transfer from the so-called hot venting gas of the battery cells to neighboring cells in the event of a thermal event in one battery cell can thus be advantageously avoided.

[0010] Furthermore, the thermal separation layer ensures cell mounting and sealing of the wet area of ​​the liquid cooling system in the cell block when direct cooling of the battery cells is implemented.

[0011] In the event of a fault, the controlled rupture of the battery cells at the rupture element can be ensured. Optimized venting cross-sections and the thermal break layer allow for a reduction in battery height.

[0012] A thermal barrier can be used to isolate the battery cells from each other, preventing thermal propagation. This thermal barrier can be implemented, for example, by applying a suitable potting compound as a coating to the venting side of the battery cells. Alternatively, a barrier can also be created using an insert.

[0013] This allows for a more compact design of the battery module, maximizing energy density and thus the range of the electrically powered vehicle.

[0014] The sealing requirement of the battery module can thus be advantageously ensured by appropriate sealing measures.

[0015] Direct cooling can improve the cooling and heating of the high-voltage battery, resulting in more favorable performance and reduced cell aging.

[0016] According to an advantageous embodiment of the battery module, the module housing can have at least one rupture disc on a side facing the rupture elements. In the event of a battery cell failure, the thermal break layer above the battery cell is penetrated by escaping venting gas. The venting gas can then escape through a narrow venting channel in the cell block from the module's designated rupture disc.

[0017] According to an advantageous embodiment of the battery module, a free space can be formed between the thermal break layer and the side of the module housing containing the at least one rupture disc. The venting gas can thus escape through this free space and be discharged into the outside via rupture discs in the module housing.

[0018] According to an advantageous embodiment of the battery module, the space around electrical connections and / or coolant connections on or within the module housing can be gas-tight and pressure-tight. This ensures that the venting gas does not damage the electrical connections and cause short circuits. Furthermore, the venting gas cannot escape through the cooling lines, which could lead to further damage in the high-voltage battery.

[0019] According to an advantageous embodiment of the battery module, the thermal break layer can be designed as a continuous layer of potting compound or as an insert. This allows for cost-effective production of the thermal break layer, reducing the overall cost of the high-voltage battery. The potting compound can be, for example, a one-component or two-component epoxy or polyurethane (PUR). An ablative, rigid film from the fire protection industry can be used as an insert. Alternatively, an injection-molded plastic part made of a flame-retardant plastic can be used.

[0020] According to an advantageous embodiment of the battery module, a filling medium can be arranged between the battery cells. This filling medium can serve to hold the battery cells and to provide a suitable seal for the coolant during direct cooling, allowing the coolant to be directed in designated areas between the batteries or the module housing.

[0021] According to an advantageous embodiment of the battery module, the filling medium can be a potting compound or an insert. The filling medium reduces the free space within the battery module, thus requiring less coolant. A suitable potting compound, such as an epoxy or polyurethane (PUR) in one-component or two-component form, can also be selected for the filling medium.

[0022] According to an advantageous embodiment of the battery module, the module housing can have at least one coolant inlet and at least one coolant outlet for a liquid coolant designed for direct cooling of the battery cells. The battery cells can be cooled efficiently via this direct cooling. Even in the event of a thermal event, heat can be dissipated effectively in this way.

[0023] According to an advantageous embodiment of the battery module, a free flow of coolant can be formed in the spaces between the battery cells, between the filling medium and the thermal break layer. The battery cells can be efficiently cooled via this free flow of coolant. In the event of a thermal event, heat can also be dissipated effectively in this way.

[0024] According to an advantageous embodiment of the battery module, at least one displacer body can be arranged between the module housing and the battery cells. The displacer body advantageously reduces the free space within the battery module, thus requiring less coolant.

[0025] Further advantages will become apparent from the following description of the drawings. The drawings illustrate an embodiment of the invention. The drawings, the description, and the claims contain numerous features in combination. A person skilled in the art will expediently consider the features individually and combine them into meaningful further combinations.

[0026] This shows: Fig. 1 a schematic longitudinal section through a battery module for a high-voltage battery of an electrically powered vehicle with a plurality of battery cells according to an embodiment of the invention; Fig. 2 a schematic longitudinal section through a battery module according to a further embodiment of the invention; Fig. 3 the battery module after Fig. 1 in a thermal event; Fig. 4 an enlarged view of part of the longitudinal section of the battery module; Fig. 5 a top view of part of the cell stack; Fig. 6 an isometric view of the battery module during the application of the thermal break layer to the underside; Fig. 7 an isometric view of the battery module during the application of the thermal break layer to the top surface; and Fig. 8 an exploded view of the battery module.

[0027] In the figures, identical or similar components are numbered with the same reference symbols. The figures merely show examples and are not to be understood as limiting.

[0028] Fig. Figure 1 shows a schematic longitudinal section through a battery module 100 for a high-voltage battery of an electrically powered vehicle with a plurality of battery cells 10 according to an embodiment of the invention.

[0029] The battery module 100 comprises a plurality of battery cells 10, which are densely packed and arranged adjacent to one another in a common module housing 40. The module housing 40 has side walls 42, which are closed off at a top by a housing top part 44 and at a bottom by a housing bottom part 46. The module housing 40 further has fastening elements 48 at the corners of the housing bottom part 46. These can be, for example, threaded bushings with an M8 thread.

[0030] The battery cells 10 can, for example, be designed as cylindrical cells. Alternatively, prismatic cells can also be used.

[0031] Each battery cell 10 has a bursting element 14 (not visible) on a first end face 12, which opens in a controlled manner at a predetermined pressure. A thermal break layer 20 is arranged on the first end face 12 of the battery cells 10, which seals tightly against the side walls 42 of the module housing 40. A free space 22 is formed between the thermal break layer 20 and the upper part of the housing 44, serving as a venting channel for the removal of venting gas from a damaged battery cell 10 in the event of a thermal event.

[0032] The thermal break layer 20 can be a continuous layer of a potting compound 26 as in the embodiment shown in Fig. The potting compound 26, as shown in Figure 1, can be, for example, an epoxy or polyurethane (PUR) in one-component or two-component form.

[0033] Advantageously, the thermal break layer 20 prevents hot venting gases from a battery cell 10 from heating neighboring battery cells 10 in the event of a thermal event in that cell. This effectively prevents thermal propagation within the battery module 100.

[0034] A filling medium 30 is arranged in two sections between the battery cells 12. The filling medium 30 can also be a potting compound 32. For cost reasons, the same material can be used for the potting compound 26 as a thermal break layer 20 and for the potting compound 32 as a filling medium 30 to reduce the free space in the battery module.

[0035] A corresponding high-voltage connection 50 is arranged on the module housing 40, which is electrically coupled to the battery cells 10 via a cell contacting device 52, for example, a printed circuit board. The corresponding electrical terminals 16 of the battery cells 10 are interconnected by cell connectors 54, for example, in series and / or parallel. The battery terminals 16 face the underside 46 of the housing. The cell connectors 54 are each electrically connected to the battery terminal 16 of one battery cell 10 and to the cell housing of the adjacent battery cell 10.

[0036] A low-voltage connection 56 is also arranged on the module housing 40, which is electrically connected to a cell monitoring electronics 58 via a low-voltage cable set.

[0037] The module housing 40 further features a coolant inlet 60 and a coolant outlet 62 for a liquid coolant 64 for direct cooling of the battery cells 12. Coolant inlet 60 and coolant outlet 62 are shown schematically by arrows. A free flow of the coolant 64 can thus develop in the spaces between the battery cells 12, between the filling medium 30 and the thermal break layer 20, by means of which the battery cells can be effectively cooled. The flow of the coolant 64 is symbolized by arrows. The main flow thus runs along the underside of the battery module 100 between the lower housing part 46 and the battery terminals 16 of the battery cells 10. The majority of the heat loss from the battery cell 10 during normal operation is generated in the area of ​​the battery terminals 16. Therefore, cooling with a coolant 64 is most effective there.

[0038] The coolant 64 flows upwards at the end of the lower housing part 46 along the side wall 42. The larger portion of the coolant 64, indicated by the thick arrow, then flows between the battery cells 10, specifically in the free space between the areas containing the filling medium 30, back to the coolant outlet 62. A smaller portion of the coolant 64, indicated by the thin arrow, flows into the free space 22 above the thermal break layer 20 and from there back to the coolant outlet 62.

[0039] In the area of ​​the coolant inlet 60 and the coolant outlet 62, a displacement body 34 is arranged between the module housing 40 and the battery cells 12 to reduce the free volume in the module housing 40. The displacement body 34 can, for example, be made of the potting compound 32 of the filling medium 30. Alternatively, the displacement body 34 can also be a plastic insert.

[0040] Fig. Figure 2 shows a schematic longitudinal section through a battery module 100 according to a further embodiment of the invention.

[0041] The battery module 100 has essentially the same features as the one in Fig. The battery module 100 is shown in Figure 1. In contrast, the module housing 40 has a series of rupture discs 70 on a side 43 facing the rupture elements 14 of the battery cells 10. As in the previous embodiment, a free space 22 is formed between the thermal break layer 20 and the side 43 of the module housing 40 with the rupture discs 70. This allows venting gases from a battery cell 10, in which a rupture element 14 opens during a thermal event, so that the released venting gases can escape and penetrate the thermal break layer 20, to flow through the free space 22 as a venting channel to open at least one rupture disc 70 and escape into the outside space.

[0042] The free space 22 is expediently designed to be gas-tight and pressure-tight from the electrical connections 50, 56 and the coolant connections 60, 62 on or in the module housing 40. This ensures that the venting gas does not damage the electrical connections 50, 56 and cause short circuits. Furthermore, the venting gas cannot escape via the cooling lines, which could lead to further damage in the high-voltage battery.

[0043] In this embodiment, the battery cells 10 are further mechanically held by means of a stamped grid 72, which is arranged in an upper and a lower region of the battery cells 10. The stamped grid 72 can, for example, be made of a plastic.

[0044] In Fig. 3 is the battery module after Fig. 1 shown in a thermal event.

[0045] The bursting element 14 of a battery cell 10 has opened, allowing venting gases to escape. The gases have penetrated the thermal break 20 and are flowing along the free space 22 of the module housing 40. At higher gas pressures, the module housing 40 can open at a weak point. In the illustrated embodiment, this occurs at the connection between the upper housing part 44 and the side wall 42. The upper housing part 44 is partially lifted, allowing the released gases 82, shown as arrows, to flow into the outside space.

[0046] Fig. Figure 4 shows an enlarged view of part of the longitudinal section of the battery module 100 with typical dimensions of the embodiment.

[0047] A typical diameter 90 of a cylindrical cell, as a battery cell 10, can be 25.9 mm. The filling medium 30 with the potting compound 32 has an outer diameter 92 of 26.1 mm as a space for the battery cell 10. The gap between the cell shell and the filling medium 30 can advantageously be a maximum of 0.4 mm. The height 95 of the filling medium 30 can, for example, be 37 mm. The spacing 91 between the battery cells 10 can typically be 1.5 mm.

[0048] The thermal break layer 20 can be arranged as a potting compound 26 with a penetration depth 94 of 6.5 mm between the battery cells 10. The height 93 of the thermal break layer 20 above the battery cells 10 can advantageously be 1.0 ± 0.5 mm.

[0049] In Fig. Figure 5 shows a top view of part of the cell stack 11 to illustrate the distance 91 between the battery cells 10. The battery cells are embedded in the potting compound 26 of the thermal break layer 20.

[0050] In the Fig. Figures 6 to 8 show a real battery module 100. Fig. Figure 6 shows an isometric representation of the battery module 100 during the application of the thermal separation layer 20 to the underside of the cell stack 11. Fig. Figure 7 shows the battery module 100 during the application of the thermal break layer 20 to the top surface, while in Fig. Figure 8 shows an exploded view of battery module 100.

[0051] The cell stack 11, consisting of a multitude of battery cells 10, is arranged in the module housing 40. The lower housing part 46 is in Fig. 7 removed, so that the cell stack 11 is directly visible. The potting compound 26 of the thermal break layer 20 is recognizable as a black area in the spaces between the battery cells 10.

[0052] In Fig. Figure 7 shows the upper housing part 44 of the module housing 40 removed. The potting compound 26 of the thermal break layer 20 has been partially applied and is visible here as a continuous white area over the battery cells 10.

[0053] At the end of the module housing 40, the high-voltage connections 50 as well as the coolant inlet 60 and coolant outlet 62 are visible.

[0054] The exploded view in Fig. Figure 8 serves to illustrate the structure of the battery module 100 from individual components.

[0055] The module housing 40 is shown with the cell stack 11 inserted and the upper housing part 44 and lower housing part 46 removed.

[0056] The cell stack 11 is shown separately. The low-voltage connection 56 and the cell monitoring electronics 58 are also shown.

[0057] The high-voltage connection of the battery cells 10 is made via the cell contacting device 52 with cell connectors 54.

[0058] The thermal separation layer 20 is shown as a continuous potting compound 26 over the module housing 40 and as a potting compound 26 with the recesses for the battery cells 10 between cell stack 11 and cell contacting device 52. Reference symbol list 10 battery cells 11 cell stacks 12 Front 14 Burst element 16 battery terminals 20 thermal break layer 22 Free space 24 Height Free space 26 Potting compound 28 insert 30 Filling medium 32 Potting compound 34 Displacement bodies 36 Gas containment 40 module housings 42 side wall Page 43 44 Housing top 46 Lower housing part 48 Fastening element 50 high-voltage connection 52 cell contacting device 54 cell connectors 56 Low-voltage connection 57 Low-voltage wiring harness 58 cell monitoring electronics 60 Coolant inlet 62 Coolant outlet 64 Coolant 70 Burst disc 72 punched grids 80 thermal event 82 escaping gases 90 diameter battery cell 91 Distance between battery cells 92 outer diameter cell space 93 Height of separator layer above battery cell 94 Penetration depth of the separating layer 95 Height potting compound 100 battery modules QUOTES INCLUDED IN THE DESCRIPTION

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

[0000] DE 10 2020 127 589 A1

[0004]

Claims

[1] Battery module (100) for a high-voltage battery of an electrically powered vehicle with a plurality of battery cells (10) which are arranged in a densely packed manner in a common module housing (40), wherein the battery cells (10) each have a bursting element (14) on a first end face (12) which opens in a targeted manner at a predetermined pressure, wherein a thermal separation layer (20) is arranged on the first end face (12) of the battery cells (10), wherein the thermal separation layer (20) is tightly sealed with side walls (42) of the module housing (40). [2] Battery module according to claim 1, wherein the module housing (40) has at least one bursting disc (70) on a side (43) facing the bursting elements (14). [3] Battery module according to claim 2, wherein a free space (22) is formed between the thermal separation layer (20) and the side (43) of the module housing (40) with the at least one bursting disc (70). [4] Battery module according to claim 3, wherein the free space (22) to electrical connections (50, 56) and / or coolant connections (60, 62) on or in the module housing (40) is designed to be gas-tight and pressure-tight. [5] Battery module according to one of the preceding claims, wherein the thermal separation layer (20) is formed as a continuous layer of a potting compound (26) or as an insert (28). [6] Battery module according to one of the preceding claims, wherein a filling medium (30) is arranged between the battery cells (12). [7] Battery module according to claim 6, wherein the filling medium (30) is formed by a potting compound (32) or as an insert. [8] Battery module according to one of the preceding claims, wherein the module housing (40) has at least one coolant inlet (60) and at least one coolant outlet (62) for a liquid coolant (64) which is designed for direct cooling of the battery cells (12). [9] Battery module according to claim 8, wherein a free flow of the coolant (64) is formed in spaces between the battery cells (12) between the filling medium (30) and the thermal separation layer (20). [10] Battery module according to one of the preceding claims, wherein at least one displacement body (34) is arranged between the module housing (40) and the battery cells (12).

Images