Swell seal for a battery module and method for providing a battery module

Abstract

In various embodiments, a swelling seal (10), in particular for sealing a gas vent (4) of a battery cell (3), is provided with an annular sealing body (12) in which at least one substantially circumferential recess is arranged; and a swelling material (11) which is arranged in the at least one circumferential recess. Furthermore, a method for providing a battery module (1) is provided.

Description

[0001] The present invention relates to a swelling seal for a battery module and a method for providing a battery module.

[0002] As is well known, electric vehicles are powered by an electric motor that draws its energy from a high-voltage battery, also known as a traction battery. A traction battery typically comprises several so-called battery modules, each of which contains a plurality of battery cells arranged and interconnected in a battery module housing.

[0003] Battery systems in modern electric vehicles are designed for high power flows, which can be in the range of several hundred kilowatts, especially during fast charging and sharp acceleration. One problem that efficient cooling systems, among other things, attempt to prevent is so-called thermal runaway. This term refers to the overheating of a battery cell due to a self-reinforcing exothermic process taking place within it. This usually results in the outgassing of hot chemical components in a battery. Thermal runaway can thus trigger a fire or, due to the increase in pressure resulting from the outgassing, even cause the affected battery cell to explode. In the worst case, this can damage the battery module or even the entire traction battery, not to mention possible personal injury.

[0004] To prevent a battery cell from bursting, a cell vent can be provided on the cell housing. This means a defined outgassing opening which opens when there is excess pressure. The cell vent usually has a bursting membrane which ruptures when there is a defined excess pressure and thus allows the battery cell to degas. A vent is also provided on the battery module housing to allow the battery module to degas if the pressure in its interior exceeds a limit due to outgassing from the damaged battery cell. Since vehicle manufacturers are increasingly using battery modules with directly cooled battery cells, in which the battery cells are cooled by direct contact with a cooling fluid flowing through the battery module, special precautions must be taken to prevent outgassing from the battery cells if necessary.of the battery module and, on the other hand, to provide a fluid-tight flow channel inside the battery module.

[0005] Document DE 10 2022 000 147 A1 discloses a battery for a motor vehicle, comprising a housing in which at least one cell block with a plurality of storage cells for storing electrical energy is arranged, characterized by direct cooling, which has at least one coolant path through which a liquid, dielectric coolant can flow directly onto and around at least a respective partial area of ​​the storage cells to cool the storage cells, and at least one swelling seal which is held on the housing and directly delimits at least part of the coolant channel and is formed from a material which swells upon contact with the coolant.

[0006] Against this background, the object of the invention can be seen in creating a possibility to provide a reliable seal that can be used within a battery module to seal an outgassing channel.

[0007] This object is achieved by means of the subject matter of the independent patent claims. Further preferred embodiments can be found in the dependent patent claims.

[0008] According to the invention, a swelling seal is provided, in particular for sealing an outgassing opening of a battery cell, which has an annular sealing body in which at least one substantially circumferential recess is arranged, and a swelling material which is arranged in the at least one circumferential recess.

[0009] The ring shape of the sealing body can be round, oval, elliptical, or rectangular / square with rounded corners. The geometric shape of the sealing body can be determined by the shape of an exhaust opening formed in the battery cell and / or by the shape of a venting opening arranged in a battery module housing, so that the sealing body can be arranged around the larger of the two openings.

[0010] The material from which the sealing body is formed may be a material that swells upon contact with a coolant.

[0011] The swellable material arranged in the at least one substantially circumferential recess can comprise a material that swells automatically, for example, from the point at which the last manufacturing step of the expandable seal is carried out. The last manufacturing step can, for example, comprise filling the swellable material into the at least one recess. Therefore, the swellable material can comprise a (self-)swelling material that, for example, comprises a blowing agent that leads to swelling of the swellable material in a chemical reaction. Furthermore, the swellable material can be a material that swells upon contact with air. The swelling material can be introduced into the at least one recess (immediately) before the assembly of the expandable seal.

[0012] The swellable material can comprise a thermoplastic-elastomer composite that swells upon contact with air. Such materials can be produced from rubber powders, thermoplastic granules, and materials that swell strongly in water. The latter can be natural substances, such as polysaccharides, or synthetic materials, such as polyacrylates.

[0013] According to a further embodiment of the expandable seal, the recess can correspond to a recess that is closed to the surface of the sealing body. In other words, the recess in the sealing body can be in the form of a hollow volume. The swellable material can be injected into the hollow volume to form the expandable seal.

[0014] According to a further embodiment of the expansion seal, which is an alternative to the one described in the previous paragraph, the recess can correspond to a recess open to the surface of the sealing body. In this embodiment, the recess is in the form of a groove formed in the surface of the sealing body. The groove can be arranged on a top side and / or a bottom side of the sealing body. The top side and the bottom side of the sealing body can correspond to those sides of the sealing body that essentially face or abut against those surfaces between which a sealing effect is to be achieved by means of the expansion seal.

[0015] The at least one recess in the sealing body is a substantially circumferential recess. This means that it is not detrimental to the meaning and purpose of the recess in the context of the present invention if the recess has at least one interruption so that, for example, no annular flow can form along the recess. The meaning and purpose of the substantially circumferential recess is to arrange the swelling material in such a way that it can exert its effect completely around the opening arranged in the sealing body. Interruptions in the circumferential shape over a distance of approximately 1 or 2 millimeters with a circumference of the opening arranged in the sealing body of, for example, several centimeters are not detrimental to the implementation of the present invention.Such embodiments are therefore considered to have substantially circumferential recesses and are therefore within the scope of the present invention.

[0016] According to a further embodiment of the expansion seal, it can have the shape of a flat annular disc, whereby the geometric shape can correspond to one of the previously mentioned shapes. The sealing body can, for example, have the shape of a flat strip in cross-section along its circumference.

[0017] According to the invention, a method for providing a battery module is further provided. The method first comprises providing a battery module housing. In a next step, the method comprises introducing at least one battery cell into the battery module housing, wherein the battery cell has an outgassing opening. The method further comprises introducing the previously described expansion seal into the battery cell housing. If a plurality of battery cells, for example as a cell stack, are introduced into the battery module housing, the number of expansion seals can correspond to the number of battery cells, since each battery cell has an outgassing opening.

[0018] Generally, there are two options for inserting the (at least one) expansion seal into the battery module housing. The expansion seal can be inserted into the battery module housing together with the at least one battery cell, whereby it is arranged around the battery cell's exhaust opening. This means that the expansion seal can be attached to the at least one battery cell (e.g., by gluing) and then inserted into the battery cell housing together with it.

[0019] Alternatively, the swelling seal can be introduced into the battery module housing separately from the at least one battery cell, in particular before or after the introduction of the at least one battery cell into the battery module housing.

[0020] According to a further embodiment of the method, the expandable seal can be introduced into the battery module housing before the at least one battery cell is inserted and attached to the housing wall. The expandable seal can be dimensioned such that it is arranged around an exhaust opening present in the battery module housing wall. Within the scope of this embodiment, the expandable seal can be glued to the battery module housing wall or attached in any other manner.

[0021] According to a further embodiment of the method, the expansion seal can be introduced after the at least one battery cell has been inserted into the battery module housing. The expansion seal can be inserted between the at least one battery cell inserted in the battery module housing and the inner wall of the battery module housing.

[0022] According to a further embodiment of the method, the swelling seal can be arranged after introduction into the battery module housing such that it is arranged around a degassing opening present in the housing wall of the battery module housing.

[0023] According to a further embodiment of the method, a sealing effect between an outer side of the at least one battery cell and an inner side of the battery module housing can be achieved by means of the swelling seal.

[0024] Thus, the through-hole running through the expansion seal can function as a flow channel between the gas outlet opening in the cell housing wall and the gas outlet opening in the battery module housing. This flow channel is sealed from the interior of the battery module.

[0025] According to a further embodiment of the method, the swelling seal can delimit a portion of a coolant channel running through the battery module. The coolant path can further be delimited by portions of the inner wall of the battery module housing and portions of the outer wall of the at least one cell housing. By means of such a coolant path, which is implemented component-wise by a corresponding coolant channel, direct cooling of the battery cells can be realized, in which the coolant flowing through the battery module housing is in direct contact with the battery cells arranged therein.

[0026] According to a further embodiment of the method, this may further comprise introducing a coolant into the battery module along the coolant path to bring the coolant into contact with the swelling seal. Advantageously, in this embodiment, the swelling seal may comprise or be made of a material that swells upon contact with a coolant. This allows for further expansion of the swelling seal, which can further enlarge and strengthen the sealing surface.

[0027] It is understood that the features mentioned above and those to be explained below can be used not only in the combination specified in each case, but also in other combinations or on their own, without departing from the scope of the present invention.

[0028] Further advantages and embodiments of the invention will become apparent from the description and the accompanying drawings. Fig. 1 shows a battery module during its production by means of the method according to the invention according to one embodiment. Fig. 2A shows an exemplary swelling seal according to an embodiment of the present invention. Fig. 2B shows the Fig. 2A shown swelling seal in a cross-sectional view. Fig. 3 to 5 illustrate substeps of the method for providing a battery module according to an embodiment of the present invention.

[0029] The present invention is fundamentally concerned with causing a swellable or expanding seal to swell shortly after assembly. This compresses it between the surrounding walls of the battery module housing and the battery cell, thereby achieving at least a preliminary sealing effect before the coolant is introduced. The expanding seal according to the present invention is designed such that, at the end of the manufacturing process described herein, it is so swollen that no leakage occurs when the battery modules are filled with the cooling medium. During this assembly step—the filling of the coolant—the subsequent system pressure of the coolant is not yet present. The seal created using the expanding seal according to the invention must therefore bear against the sealing partners and only “lightly” seal the battery module interior against the environment.

[0030] In Fig. 1 shows a battery module 1 during its manufacture by means of the method according to the invention according to one embodiment. The battery module 1 has a battery module housing 2 in which battery cells 3 are inserted, of which Fig. 1 shows one of these as a representative example. The battery cell 3 has an exhaust opening 4 on its underside, which is sealed with a bursting membrane. A coolant channel 6 is arranged below the battery cell 3. The battery module 3, in turn, has a vent opening 5.

[0031] On the underside of the battery cell 3, a swelling seal 10 is arranged around the outgassing opening 4. The outgassing opening 4 is also arranged above, in this embodiment, flush with, the degassing opening 5 of the battery module housing 2. Grooves are incorporated into the swelling seal 10, in which a swellable material 11 is arranged. Fig. Figure 1 shows a state of the battery module 1 immediately after the assembly of the battery cells 3 in the battery module housing 2. The battery cells 3 or the cell stacks are inserted laterally into the battery module housing 2 (into the plane of the sheet), which may be an extruded profile.

[0032] In the Fig. 1, there is still play between the battery cell 3 and the lower inner wall of the battery module housing 2. In the following, Fig. 3 to 5 illustrate the method according to the invention for producing the battery module 1.

[0033] First of all, Fig. 2A shows an embodiment of the swelling seal 10 according to the invention in greater detail. This seal comprises a sealing body 12 having a rectangular shape with rounded corners. A through-opening 13 is arranged in the sealing body 12. Around the through-opening 13, two circumferential recesses in the form of grooves are arranged in the sealing body 12, in which a swellable material 12 is arranged. Fig. 2B is the swelling seal 10 in a cross-sectional view along the Fig. 2A, the line AA is shown. Since the grooves are exposed to the underside of the expandable seal 12, the swellable material can be easily introduced into them during the production of the expandable seal 10 according to the invention.

[0034] In the following, with reference to the Fig. 3 to 5, starting from the Fig. 1, an embodiment of the method according to the invention for providing the battery module 1 is illustrated. Fig. 3 to 5 shown representations to the marked area 7 in Fig. 1. Elements that have already been identified with reference to the Fig. 1 to 2B have the same reference numerals and will not be described in detail again.

[0035] In order to seal the expansion joint after the assembly of at least one battery cell 3 or a cell stack in the Fig. 3, the previously mentioned recesses are provided in the expandable seal 10, into which a swellable or swelling material 11 is introduced prior to assembly. In addition to the previously mentioned possibilities, the swellable material 11 can be, for example, a grease containing at least one swelling agent. In the state in which the expandable seal is introduced into the battery module housing 2, whether together with the at least one battery cell 3 or separately, the expandable seal 10 is still relatively thin and not swollen. The Fig. The swelling process of the sealing body 12 indicated in Figure 3 starts in the areas where the sealing body 12 comes into contact with the swelling medium 11. The sealing body 12 then swells and thereby presses itself against its sealing partners, in this case the housing of the battery cell 3 around the outgassing area 4 and the inner surface of the battery module housing 2 around the area of ​​the venting opening 5. The contact force of the swelling seal 10 against the adjacent sealing surfaces now creates a sealing effect, and the swelling seal 10 seals.

[0036] In Fig. 4 illustrates a further step in which, after the first phase of pre-swelling the sealing body 12 for the purpose of forming the seal, the coolant 8 is filled into the corresponding coolant lines of the battery module 1, including the coolant channel 6. In this state, there are no leakage points for the coolant 8 and it therefore remains completely within the battery module 1.

[0037] In the illustrated embodiment, the coolant 8 is also used as a swelling agent. For this purpose, the material of the sealing body 12 is one that swells upon contact with the coolant 8. As shown in Fig.As shown in Figure 5, the expansion seal 10 expands further, particularly in all contact areas with the coolant 8. This further increases the contact surface and contact pressure of the expansion seal. The expansion seal 10 expands completely and forms the maximum compression, thereby achieving its maximum intended sealing effect. In this state, the expansion seal 10 achieves its final intended sealing effect.

[0038] The present invention is particularly suitable for HV batteries with direct cooling. Such battery casings have numerous outgassing openings that must be sealed. 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 2022 000 147 A1

[0005]

Claims

[1] Source seal (10), in particular for sealing an outgassing opening (4) of a battery cell (3), comprising: an annular sealing body (12) in which at least one substantially circumferential recess is arranged; and a swellable material (11) which is arranged in the at least one circumferential recess. [2] Swelling seal (10) according to claim 1, wherein the recess corresponds to a recess closed to the surface of the sealing body (12). [3] Swelling seal (10) according to claim 1, wherein the recess corresponds to a recess open to the surface of the sealing body (12). [4] Source seal (10) according to one of claims 1 to 3, wherein the source seal (10) has the shape of a flat annular disc. [5] Method for providing a battery module (1), comprising: Providing a battery module housing (2); Inserting at least one battery cell (3) into the battery module housing (2), wherein the battery cell (3) has an outgassing opening (4); Introducing a swelling seal (10) according to one of claims 1 to 4 into the battery cell housing (2), wherein the swelling seal (10) is introduced into the battery module housing (2) together with the at least one battery cell (3), wherein it is arranged around the outgassing opening (4) of the battery cell (3); or wherein the swelling seal (10) is introduced into the battery module housing (2) separately from the at least one battery cell (3). [6] Method according to claim 5, wherein the swelling seal (10) is introduced into the battery module housing (2) before the at least one battery cell (3) is introduced and is fastened to the housing wall thereof. [7] Method according to claim 5, wherein the swelling seal (10) is introduced after the introduction of the at least one battery cell (3) into the battery module housing (2). [8] Method according to one of claims 5 to 7, wherein the swelling seal (10) is arranged after introduction into the battery module housing (2) such that it is arranged around a degassing opening (5) present in the housing wall of the battery module housing (2). [9] Method according to one of claims 5 to 8, wherein a sealing effect between an outer side of the at least one battery cell (3) and an inner side of the battery module housing (2) is achieved by means of the swelling seal (10). [10] Method according to one of claims 5 to 9, wherein the source seal (10) delimits a part of a coolant channel (6) extending through the battery module (1). [11] The method of claim 10, further comprising: Introducing a coolant (8) into the cooling channel (6) of the battery module (1) in order to bring the coolant (8) into contact with the swelling seal (10).

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