Housing containing battery cells to form at least part of a traction battery for an electric vehicle

Abstract

The invention relates to a housing (1) with battery cells for forming at least part of a traction battery for an electric vehicle, wherein the housing (1) has at least one through-opening (11) through which a free passage from an interior of the housing (1) to the external environment of the housing (1) is created. The through-opening (11) is covered by a cover device (4) made of heat-resistant material. According to the invention, it is proposed that the cover device (4) projects into the passage opening (11) from the outside and is supported by a circumferential edge region on a circumferential wall (10) of the housing (1) that limits the passage opening (11), wherein the cover device (4) has at least one cavity.

Description

[0001] The invention relates to a housing with battery cells for forming at least part of a traction battery of an electric vehicle with the features of the preamble of patent claim 1.

[0002] In the general state of the art, electric vehicles, including hybrid vehicles, house several battery cells in a single housing and combine them into a so-called battery module. Depending on the desired range, an electric vehicle's traction battery can have one or more battery modules combined into a battery pack.

[0003] Under certain exceptional circumstances, battery cells can experience a so-called thermal runaway. This means that an exothermic chemical reaction takes place within a battery cell, which can quickly lead to an uncontrollable state of the battery cell, accompanied by a sharp increase in temperature and thus to battery cell failure. Thermal runaway creates hot vent gases. If the vent gases are not adequately removed, they can accumulate in the battery module, causing the pressure and temperature throughout the battery module to rise.

[0004] This can cause a battery module to enter what's known as thermal propagation. This means that, in a chain reaction, all battery cells in the battery module enter thermal runaway one after the other.

[0005] To counteract thermal propagation, the battery module housings can, for example, be provided with openings on their top side, located in the assembly position, through which vent gases generated in the event of a thermal runaway can easily escape the affected battery module. However, for thermal and electrical safety reasons, these openings must not remain open, but must be covered by a layer or layers of a heat-resistant material (e.g., mica) (see US 2023 / 0 178 845 A1).

[0006] However, covering the holes results in resistance to the outflow of vent gases from the battery module and increases the residence time of vent gases in the battery module.

[0007] From KR 10 2022 0 165 187 A, a battery module is known that has the features of the preamble of patent claim 1. Specifically, a battery module with a housing is presented, which has several chambers. Each chamber accommodates battery cells. Additionally, each chamber is provided with several openings on its upper side to allow any vent gases that may arise to escape more easily. To cover the openings, each chamber is provided with a covering layer made of heat-resistant material on its inner side.

[0008] EP 4 199 215 A1 describes a battery module with a plurality of battery cells. A module housing accommodates the battery cells, wherein the module housing includes an upper plate positioned on top of the battery cells and a lower plate positioned beneath the battery cells. Each of the plates has a channel through which a coolant flows. The plates have a melting point that causes the plates to melt when heated with the battery cells to this melting point. The plates further have vent holes for the escape of vent gases, which are closed by sealing elements made of thermally fusible material.

[0009] Finally, EP 3 624 214 A1 discloses a battery module comprising a plurality of cylindrical battery cells, each having a battery housing in which an electrode assembly and an electrolyte are housed. Furthermore, a cell frame is provided with a plurality of plate elements that are bent and coupled such that they intersect one another and form receiving spaces for the battery cells. A cover is connected to the cell frame and has flame outlets for the receiving spaces.

[0010] DE 10 2020 132 188 A1 discloses a covering device for a battery cell housing, comprising a membrane and a mandrel associated with the membrane. The mandrel pierces the membrane if it is deformed due to excessive pressure in the housing.

[0011] WO 2023 / 167 467 A1 discloses a battery cell in which venting openings of a battery cell housing are closed by means of a filter element.

[0012] US 2023 / 0 291 071 A1 discloses a battery module with multiple battery cells accommodated in a module housing. Venting openings are integrated into the module housing and are each closed by a closure element. The closure elements each comprise a first closure element designed as a bursting element and a second closure element designed as a filter element.

[0013] The present invention is based on the object of proposing a housing with battery cells for forming at least part of a traction battery of an electric vehicle, in which it is made possible in a simple and reliable manner that vent gases arising in the event of a thermal runaway can escape quickly.

[0014] This object is achieved by a housing with battery cells for forming at least part of a traction battery of an electric vehicle with the features of patent claim 1. Advantageous developments of the invention can be found in the dependent claims.

[0015] The invention is based on a housing with battery cells for forming at least part of a traction battery of an electric vehicle. The housing has at least one through-opening through which a free passage from an interior of the housing to the exterior of the housing is created. The through-opening is covered by at least one covering device made of heat-resistant material.

[0016] The cover device protrudes from the outside into the through-opening and rests with a peripheral edge region against a peripheral wall of the housing that defines the through-opening. The cover device has at least one cavity.

[0017] These features propose a housing with battery cells for forming at least part of a traction battery, in which vent gases generated in the event of a thermal runaway can easily and reliably escape from the interior of the housing to the outside. In particular, the cavity enables deformation of the cover device, which contributes to easier release of the cover device from the through-opening as the internal pressure increases. On the other hand, the secure support also ensures that the interior of the housing is reliably protected from the penetration of vent gases, foreign bodies, or the like as external pressure increases. This can significantly reduce the risk of thermal propagation spreading from one battery module to another.

[0018] The housing wall defining the through-opening has at least one circumferential shoulder against which a circumferential shoulder of the cover device rests. The cover device has a first wall facing the interior and a second wall facing the exterior. The cavity is also defined by these walls, with the first wall being connected to the circumferential shoulder via a wall perpendicular to the first wall. The circumferential shoulder, in turn, transitions into a flange-like protruding wall that bears against an outer side of the housing wall.

[0019] It has been shown that these features can additionally contribute to the fact that the passage opening can be reliably protected against the penetration of vent gases from the outside and that the cover device can be reliably and quickly released from the passage opening when the internal pressure increases.

[0020] The covering device is preferably designed in the form of a plug or lid and is preferably dimensioned such that it can be pressed into the through-opening from the outside by applying slight manual force.

[0021] According to a highly advantageous embodiment of the invention, it is proposed that the cavity have a surface area that corresponds at least to a large part of the surface area of ​​the through-opening. Thus, even slight increases in pressure can lead to a deformation of the outer contour and thus to the detachment of the cover device from the through-opening. This enables a particularly rapid and early removal of vent gases from the interior of the housing.

[0022] According to a further development of the invention, a plurality of through-openings are provided, wherein the through-openings are distributed over at least one side of the housing. Each through-opening is covered by a separate cover device. This contributes to comprehensive protection of the housing against the occurrence of overpressure or excessive heat. In the event of a thermal runaway, a rising internal pressure in the housing can thus always be relieved by a controlled opening of a nearby through-opening. The through-openings can, for example, be distributed over a top side of the housing that exists in the housing's assembly position.

[0023] A further embodiment of the invention proposes that a wall of the cover device facing the interior of the housing be aligned flush with an inner side of the housing or be only slightly offset inwardly or outwardly. This creates the best possible contact surface for the resulting internal pressure, while nevertheless not restricting the interior of the housing.

[0024] Furthermore, according to a further development, it is expedient if an outer side of the housing wall, which has the through-openings, is covered with a cover made of heat-resistant material, wherein the cover devices are recessed into openings in the cover and fill them. An outer side of the cover devices is flush with an outer side of the cover. This contributes to good protection of the housing against external heat effects, while the space required by the housing is not unnecessarily increased despite the cover devices.

[0025] A further object of the invention is to propose a suitable covering device for use with a housing according to the invention with battery cells for forming at least part of a traction battery of an electric vehicle.

[0026] This object is achieved by a covering device for covering a through-opening of a housing with battery cells having the features of patent claim 5. Advantageous further developments and refinements can also be found in the respective subclaims.

[0027] According to the invention, a cover device for covering a through-opening of a housing with battery cells is proposed. The cover device is made of heat-resistant material and has a peripheral edge region with a circumferential shoulder. The circumferential shoulder merges into a flange-like, protruding wall, wherein the cover device has at least one cavity. This enables, on the one hand, very reliable support of the cover device on the wall of the housing with a good sealing effect when the cover device is used. On the other hand, the deformability of the cover device is supported under increased internal pressure, thus contributing to easier removability of the cover device.

[0028] The covering device has a first wall and a second wall aligned parallel to the first wall, wherein the cavity is also delimited by the walls. The first wall is connected to the circumferential shoulder via a wall perpendicular to the first wall, wherein the circumferential shoulder merges into the flange-like projecting wall. A thickness of the first wall is smaller than a thickness of the second wall. Preferably, the thickness of the first wall is at most half the thickness of the second wall. This contributes to easy deformability of the covering device when pressure acts on the first wall. However, when pressure acts on the second wall from the outside, good dimensional stability and thus secure support of the covering device can be ensured.

[0029] According to a further development, the cavity extends over a large part of the surface area of ​​the cover device. This allows for even easier and more controlled release of the cover device in the event of a pressure increase inside the housing.

[0030] Finally, the present invention also aims to protect an electric vehicle with a traction battery, which has at least one housing according to the invention with battery cells. Such an electric vehicle is improved in its safety against thermal propagation.

[0031] A preferred embodiment of the invention is illustrated in the figures and will be explained in more detail in the following description with reference to the figures. This will also make further features and advantages of the invention clear. Identical reference symbols, even in different figures, refer to identical, comparable, or functionally identical components. Corresponding or comparable properties and advantages are achieved even if a repeated description or reference to them is not made. The figures are not, or at least not always, to scale. In some figures, proportions or distances may be exaggerated in order to emphasize features of an embodiment more clearly.

[0032] They show, schematically Fig. 1 a perspective view of a housing with battery cells and through openings, Fig. 2 a view of the housing according to view II of Fig. 1, wherein a cover of the housing and covering devices for the through openings are also shown, Fig. 3 a sectional view according to section view III of Fig. 2, Fig. 4 a sectional view comparable to Fig. 3, but before inserting the cover device into the through opening, Fig. 5 a sectional view comparable to Fig. 3, but after inserting the cover device into the through-hole and when internal pressure occurs due to vent gases and Fig. 6 an electric vehicle with a traction battery comprising several housings with battery cells.

[0033] In Fig. 1 shows a housing 1 in which several battery cells 2 are accommodated. The housing 1 with the battery cells 2 forms a battery module. The necessary electrical system is not shown in detail and is also not important for understanding the invention. The battery cells 2 are designed as so-called pouch cells and are layered next to one another in the housing 1 with their flat sides in a layer direction S. The housing 1 is cuboid-shaped and has a wall 10 with several through-openings 11 on its upper side, which can be seen in the figure.

[0034] From the Fig. 2, which shows the housing 1 from above, additionally shows a cover 3 made of heat-resistant material, for example, mica. The cover 3 is preferably glued to the wall 10 and has openings 30 aligned with the through-openings 11 in the wall 10.

[0035] The openings 30 are each covered by a covering device 4, with only one covering device 4 being shown as an example. Both the through-openings 11 and the openings 30 and the covering devices 4 are elongated in outline, in particular rectangular in shape, with a surface area F. Other outline shapes are conceivable.

[0036] Based on the Fig. 3 to 5 that the cover device 4 is inserted from the outside into the through-opening 11 and projects into it. The cover device 4 has a cross-section of a first wall 41, which is horizontally oriented in the assembled position and faces an interior space 100 containing the battery cells 2. The wall 41 is connected on both sides to a vertically upwardly extending wall 42, which merges into a circumferential shoulder 43. The circumferential shoulder 43 finally merges into a flange-like projecting wall 44. The flange-like projecting wall 44 is thus perpendicular to the wall 42. The flange-like projecting wall 44 furthermore forms a common surface or outer side 45a with a second wall 45, which faces an external environment 200 of the housing 1. The second wall 45 runs parallel to the first wall 41.The circumferential shoulder 43 and the flange-like wall 44 projecting therefrom form a peripheral edge region R. The edge region R has a stepped profile when viewed in cross-section.

[0037] The cover device 4 has circumferential dimensions that are slightly larger than the through-opening 11 and the opening 30 of the cover 3. Therefore, the cover device 4 is pressed into the through-opening 11 and the opening 30 by applying a slight manual force in an assembly direction M. In the assembly position, the cover device 4 is supported with its edge region R against the wall 10 delimiting the through-opening 11. Specifically, the circumferential shoulder 43 of the cover device 4 bears against a circumferential shoulder 12 of the wall 10. The flange-like projecting wall 44 bears against an upper side 10b of the wall 10 left free by the opening 30.

[0038] A cavity 40 is formed between walls 41 and 45. The cavity can preferably be filled with air. Preferably, cavity 40 extends over a large portion of the surface area F of through-opening 11. Furthermore, it can be seen that first wall 41 has a thickness d1 and second wall 45 has a thickness d2. Thickness d1 is preferably smaller than thickness d2; more preferably, thickness d1 is at most half of thickness d2.

[0039] Based on the Fig. Figure 5 now shows how the covering device 4 behaves when an internal pressure p in the interior 100 increases, for example due to vent gases being generated.

[0040] In such a case, the pressure p acts on the entire wall 41 facing the interior space 100. Due to the cavity 40, the cover device 4 can deform more easily. In particular, the wall 41, bending to the pressure p, can deform outwardly toward the wall 45, thus assuming a concave shape from the perspective of the interior space 100. This creates a circumferential, gap-like space Z between the wall 42 of the cover device 4 and the circumferential shoulder 12 of the wall 10. This reduces the frictional force existing between the cover device 4 and the wall 10, which leads to easier removal of the cover device 4 from the through-opening 11. This effect can be further enhanced by making the first wall 41 thinner than the second wall 45.

[0041] It should also be noted that in the assembly position of the cover device 4, an outer side 45a of the cover device 4 is flush with an outer side 3a of the cover 3. Furthermore, the first wall 41 is aligned flush with an inner side 10a of the wall 10.

[0042] Finally, based on the Fig. 6 shows an electric car E, which is equipped with housings 1 containing several battery cells 2. The housings 1 form a traction battery T of the electric vehicle E. An electrical and energy connection is formed between the traction battery T and a drive motor 5 via electrical devices not further numbered. List of reference symbols 1 housing 2 battery cells 3 Cover made of heat-resistant material 3a Outside of the cover 4 Cover device 5 Drive motor, electric motor 10 Wall of the housing 10a Inside 10b Outside 11 Through hole in the housing 12 circumferential shoulder of the wall 30 cover openings 40 cavity 41 first wall 42 wall 43 surrounding heel 44 flange-like protruding wall 45 second wall 45a Outside of the cover device 100 Interior of the housing 200 external environment of the housing d1 thickness d2 thickness E electric vehicle F Area extension M Mounting direction p internal pressure R circumferential edge area S layer direction T traction battery Z circumferential space

Claims

[1] Housing (1) with battery cells (2) for forming at least part of a traction battery (T) of an electric vehicle (E), wherein the housing (1) has at least one through-opening (11) through which a free passage from an interior (100) of the housing (1) to the external environment (200) of the housing (1) is created, wherein the through-opening (11) is covered by a covering device (4) made of heat-resistant material, wherein the covering device (4) projects from the outside into the through-opening (11) and is supported with a peripheral edge region (R) on a peripheral wall (10) of the housing (1) delimiting the through-opening (11), and wherein the covering device (4) has at least one cavity (40), characterized byin that the wall (10) of the housing (1) delimiting the through-opening (11) has at least one circumferential shoulder (12) against which a circumferential shoulder (43) of the covering device (4) comes to rest, wherein the covering device (4) has a first wall (41) facing the interior (100) and a second wall (45) facing the external environment (200), wherein the cavity (40) is also delimited by the walls (41, 45) and wherein the first wall (41) is connected to the circumferential shoulder (43) via a wall (42) perpendicular to the first wall, and the circumferential shoulder (43) merges into a flange-like projecting wall (44) which bears against an outer side (10b) of the wall (10) of the housing (1). [2] Housing (1) according to claim 1, characterized by that the cavity (40) has a surface extension which corresponds at least to a large part of a surface extension (F) of the through opening (11). [3] Housing (1) according to one of the preceding claims, characterized by that a plurality of through-openings (11) are provided, wherein the through-openings (11) are arranged distributed over at least one side of the housing (1) and wherein each through-opening (11) is covered by a separate covering device (4). [4] Housing (1) according to one of the preceding claims, characterized by that a wall (41) of the covering device (4) facing the interior (100) of the housing (10) is aligned flush with an inner side (10a) of the housing (10) or is only slightly offset inwards or offset back outwards. [5] Cover device (4) for covering a through-opening (11) of a housing (1) with battery cells (2) according to one of claims 1 to 4, wherein the cover device (3) is made of heat-resistant material and has a peripheral edge region (R) with a circumferential shoulder (43) which merges into a flange-like projecting wall (44), wherein the cover device (3) has at least one cavity (40), characterized by in that the covering device (4) has a first wall (41) and a second wall (45) aligned parallel to the first wall (41), wherein the cavity (40) is also delimited by the walls (41, 45) and wherein the first wall (41) is connected to the circumferential shoulder (43) via a wall (42) perpendicular to the first wall (41) and the circumferential shoulder (43) merges into the flange-like projecting wall (44), wherein a thickness (d1) of the first wall (41) is smaller than a thickness (d2) of the second wall (45). [6] Cover device (4) according to claim 5, characterized by that the cavity (40) extends over a large part of a surface extension (F) of the covering device (4). [7] Electric vehicle (E) with a traction battery (T), characterized by at least one housing (10) according to one of claims 1 to 4.

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