Battery cell with deformation protection

Abstract

Battery cell (1) with deformation protection, comprising - a housing (2) with a housing base (3) - a sheet (4; 41; 42; 43) which is arranged inside the housing above the housing base (3) and on which an active material (5) is arranged, wherein the sheet (4; 41; 42; 43) have at least a first zone (6) and at least a second zone (7) with different first deformation resistances in a first deformation direction (R1) which runs parallel to the housing base (3), where the first zone (6) has a higher first deformation resistance in the first deformation direction (R1) than the second zone (7).

Description

[0001] The present invention relates to a battery cell with deformation protection.

[0002] To reduce the cost of battery cells, efforts are being made to reduce the wall thickness of the battery housing. At the same time, the battery cell must be able to tolerate certain deformations (e.g., in a crash). Prismatic battery cells are typically positioned transversely to the direction of travel between the axles of a vehicle, making lateral intrusion (from a side impact) a very likely cause of damage. Very thin housing walls, however, lead to significant deformation, especially in the area of ​​the safety valve, as this is inherently the weakest point of the housing. This deformation of the housing sheet very often results in significant penetration into the active material of the battery cell, potentially causing a short circuit and, in the worst case, thermal runaway.

[0003] One solution to the problem could be the use of steel housings or thicker walls. Alternatively, the vehicle chassis could be stiffer or incorporate more crumple zones to minimize intrusion into the battery system.

[0004] However, thicker cell casings lead to energy density losses. Increased chassis stiffness results in higher weight and costs. A larger crumple zone reduces the available installation space for the battery system and potentially the vehicle's range.

[0005] DE 10 2009 037 138 A1 discloses a battery housing for a battery, in particular for a battery in a motor vehicle, comprising an upper shell, a lower shell, and a shell made of a metallic material, in particular a thin metallic sheet, which surrounds the lower shell at least partially. During operation, the metallic shell provides electromagnetic shielding and, in the event of damage, supports the plastic structure and provides subsequent isolation from the environment. Only the resulting overall assembly absorbs all required forces and prevents uncontrolled local damage, such as cracks, to the plastic, as well as excessive deformation of the sheet and any resulting leakage of the overall system.

[0006] The object of the invention was to provide deformation protection for battery cells that does not have the disadvantages mentioned above.

[0007] A battery cell according to claim 1 is specified here. Further embodiments are specified in the dependent claims and this description.

[0008] The invention relates to a battery cell with deformation protection, comprising - a case with a case base, - a sheet metal panel that is positioned inside the housing above the housing base and on which an active material is arranged, wherein the sheet metal has a first zone and at least a second zone with different first deformation resistances in a first deformation direction that runs parallel to the housing base, where the first zone has a higher first deformation resistance in the first deformation direction than the second zone.

[0009] Deformation resistance is a resistance to compression in the direction of deformation.

[0010] Active material is understood to be an arrangement consisting of at least cathodes, current collector layers, and separators. Anodes may also be present.

[0011] The metal sheet is inserted between the battery cell's active material and the housing base to protect the active material from intrusion during housing deformation. The targeted creation of zones with varying deformation resistance protects the active material from housing deformation, while also allowing greater deformation in specific areas of the housing where the second zone of the sheet is located. This second zone of the sheet creates a preferred direction for deformation, permitting compression without causing the sheet to intrude into the active material.

[0012] Increasing the safety of individual battery cells in the event of a crash benefits the overall system, as fewer forces have to be borne by surrounding components.

[0013] Different levels of deformation resistance can preferably be achieved by different profiling of the sheet metal and / or by different perforations. This makes the sheet metal simple and cost-effective to manufacture.

[0014] The invention enables a reduction in the wall thickness of the housing, as deformation forces can be absorbed by the sheet metal. The additional space required in the battery cell for the sheet metal can be at least partially compensated for by reducing the wall thickness of the housing.

[0015] In one embodiment, the battery cell has a safety pressure valve arranged in the base of the housing, with the first zone being arranged above the safety pressure valve.

[0016] In this embodiment, increased deformation resistance of the sheet metal above the safety valve is achieved. The housing has a weak point in the area of ​​the safety valve, which leads to significant deformation of the housing in this region. In this embodiment, such significant deformation is not directly transferred to the active material because the protective effect of the sheet metal prevents or at least reduces the intrusion of the housing into the active material.

[0017] In one embodiment, the housing has a thinner wall in an area of ​​the housing base surrounding the safety valve than in other areas of the housing.

[0018] Reducing the housing wall thickness in the area of ​​the safety valve makes it possible, in particular, to switch the manufacturing process of the cell housing, especially the lower part of the housing, to the very efficient and inexpensive roll forming process.

[0019] In one embodiment, the first zone has through holes in the sheet metal.

[0020] The through-holes allow passage from the active material to the outside, enabling efficient venting of generated gases through a safety pressure relief valve in the event of thermal runaway of the battery. A combination with the previously described embodiment, in which the first zone is arranged above a safety pressure relief valve, is particularly advantageous.

[0021] In one embodiment, the first through-holes in the sheet metal are arranged in a two-dimensional configuration. This enables even more efficient venting of generated gases through a safety pressure valve.

[0022] In one embodiment, the second zone has two through-holes in the sheet metal. This embodiment also has the advantage of efficiently venting generated gases through a safety pressure valve.

[0023] In one embodiment, the first zone has beads extending in the first deformation direction. These beads increase the deformation resistance in the first deformation direction.

[0024] In one embodiment, the first zone and the second zone have different second deformation resistances in a second deformation direction, wherein the second deformation direction is perpendicular to the housing base, and wherein the first zone has a higher second deformation resistance in the second deformation direction than the second zone. The second deformation direction is preferably perpendicular to the first deformation direction.

[0025] In this embodiment, the aforementioned advantages of the invention are achieved in two directions of deformation. For example, the first direction of deformation can lie in or parallel to the longitudinal axis of a vehicle in which the battery cell is installed, and the second direction of deformation can lie in or parallel to the transverse axis of a vehicle. If protection against the application of forces is to be achieved essentially parallel to the transverse axis of a vehicle, this embodiment allows for two installation directions of the battery cell rotated 90° relative to each other and parallel to a vehicle floor.

[0026] In one embodiment, the battery cell has two of the second zones, with the second zones connecting to the first zone at opposite ends. This embodiment is advantageous, for example, when a safety pressure relief valve is arranged centrally in the base of the housing.

[0027] In one embodiment, the sheet metal in the first zone has a greater thickness than in the second zone. This is advantageous for achieving a higher resistance to deformation in the first zone.

[0028] In one embodiment, the sheet extends to the edges of the underside of the active material or beyond. This is advantageous for improved protection of the active material along its entire length.

[0029] The invention is described below with reference to exemplary embodiments. The figures shown are: Fig. 1a, b a non-inventive battery cell in the undeformed and deformed state; Fig. 2a, b a battery cell according to the invention in the undeformed and deformed state; Fig. 3 an embodiment of a sheet for a battery cell according to the invention in a side view and a top view; Fig. 4 another embodiment of a sheet for a battery cell according to the invention; Fig. 5 a further embodiment of a sheet for a battery cell according to the invention in a side view and a top view; Fig. 6 Another embodiment of a sheet for a battery cell according to the invention in a side view and a top view.

[0030] The in Fig. The non-inventive battery cell 13 shown in Figure 1a comprises the housing 2 with the housing base 3. The active material 5 is housed inside the housing 2. The safety pressure relief valve 8 is arranged in the housing base 3. A first deformation direction R1 is, for example, in the direction of a lateral force when the battery cell is installed in a vehicle. When a force F1 is applied by the test specimen 12 in the first deformation direction R1, the housing 2 is deformed, as shown in Figure 1a. Fig. 1b shown. When a force F2 is applied by the further test specimen 12 in the second deformation direction R2, the housing 2 is also deformed, as shown in Fig. Figure 1b shows that the housing 2 is weakened in the area of ​​the safety pressure valve 8 and is particularly severely deformed there. This results in the following: Fig. 1b shows the penetration of the particularly strongly deformed part of the housing 2 into the active material 5, resulting in the risk of an internal short circuit due to a strong deformation of the active material 5.

[0031] The in Fig. The battery cell 1 shown in Figure 2a according to the invention has the sheet metal 4 between the active material 5 and the housing base 3. The sheet metal 4 rests on the housing base 3 and the active material 5 rests on the sheet metal 4. The sheet metal 4 extends to the edges of an underside of the active material 5.

[0032] Sheet 4 shows the in Fig. 3. Structure shown in more detail. Fig. 3 - top, shows a side view, as well as Fig. 2a, and Fig. Figure 3 below shows a top view of sheet 4. Sheet 4 has the first zone 6 and two of the second zones 7, which connect to the first zone 6 at opposite ends.

[0033] The first zone 6 exhibits a higher initial deformation resistance in the first deformation direction R1 than the second zones 7. In the first zone 6, beads 11a are formed in the sheet 4, which run in the first deformation direction R1. In the second zones 7, beads 11b are formed in the sheet 4, which run in a direction rotated by 90° to the first deformation direction R1, corresponding to a second deformation direction R2.

[0034] In Fig. Figure 2b shows the effect of the sheet metal 4. When the force F1 is applied by the test specimen 12 in the first deformation direction R1, the housing 2 is deformed. In the area of ​​the safety pressure valve 8, the deformation of the housing is greater compared to Fig. 1b is reduced, which is achieved by the first zone 6, which covers the area of ​​the safety pressure valve 8. The first zone 6 has a relatively high resistance to deformation in the first deformation direction R1, which in this example is achieved by the beads 11a in the sheet 4 that run in the first deformation direction R1. Furthermore, there is also a high resistance to deformation in the deformation direction R2. Due to the low deformation of the first zone 6, good protection against severe deformation of the housing base 3 in the area of ​​the safety pressure valve 8 is achieved when a force F1 acts. By reducing and distributing the deformation of the housing base 3 in the area of ​​the safety pressure valve 8, the Fig. The penetration into the active material 5 shown in 1b is prevented, and an internal short circuit caused by strong deformation of the active material 5 is prevented. In the second zones 7, however, deformation and length compensation are possible because compression is possible due to the different orientation of the beads.

[0035] In Fig. 4 shows another embodiment of a sheet 41, with which the in Fig. The effect shown in Figure 2b can be achieved when force is applied. Dotted lines indicate the transition between several first zones 6 and second zones 7. The middle first zone 6 has first through-holes 9 and beads 11d, while the outer first zones 6 have beads 11d and second through-holes 10. The second zones 7 also have second through-holes 10. Different deformation resistances in the first deformation direction R1 are achieved through the arrangement of the beads 11d and the size and arrangement of the through-holes 9 and 10. Different deformation resistances are also achieved in the second deformation direction R2. The first through-holes 9 and the second through-holes 10 allow gases to escape from the active material 5 to the safety pressure valve 8 in the event of thermal runaway.

[0036] In Fig. Figure 5 shows another embodiment of a sheet 42. The top is as in Fig. Figure 5 shows a side view and, below, a top view of the sheet 42. The bead 11b in the second zones 7 is relatively wide. Further first zones 6, which have beads 11c, are shown to the side of the second zones 7.

[0037] In Fig. Figure 6 shows another embodiment of a sheet 43. The top is as in Fig. Figure 6 shows a side view and, below, a top view of the sheet 43. In the second zones 7, second through holes 10 are formed in each. Reference symbol list 1 battery cell 2 cases 3 Case bottom 4 sheets 5 Active material 6 first zone 7 second zone 8 Safety pressure valve 9 first through holes 10 second through holes 11a groove 11b groove 11c groove 11d groove 12 test specimens 13 battery cells 41 sheet metal 42 sheets 43 sheet metal F1 Force F2 force R1 first deformation direction R2 second deformation direction 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 2009 037 138 A1

[0005]

Claims

[1] Battery cell (1) with deformation protection, comprising - a housing (2) with a housing base (3) - a sheet (4; 41; 42; 43) which is arranged inside the housing above the housing base (3) and on which an active material (5) is arranged, wherein the sheet (4; 41; 42; 43) has at least a first zone (6) and at least a second zone (7) with different first deformation resistances in a first deformation direction (R1) which runs parallel to the housing base (3), wherein the first zone (6) has a higher first deformation resistance in the first deformation direction (R1) than the second zone (7). [2] Battery cell (1) according to claim 1, comprising a safety pressure valve (8) arranged in the housing base (3), wherein the first zone (6) of the sheet (4; 41; 42; 43) is arranged above the safety pressure valve (8). [3] Battery cell (1) according to one of the preceding claims, wherein the housing (2) has a smaller housing wall thickness in a region of the housing base (3) surrounding the safety pressure valve (8) than in other regions of the housing (2). [4] Battery cell (1) according to one of the preceding claims, wherein the first zone (6) has first through holes (9) in the sheet (41). [5] Battery cell (1) according to one of the preceding claims, wherein the first through holes (9) in the sheet (41) are arranged in a two-dimensional arrangement. [6] Battery cell (1) according to one of the preceding claims, wherein the second zone (7) has second through holes (10) in the sheet (43). [7] Battery cell (1) according to one of the preceding claims, wherein the first zone (6) has beads (11a) extending in the first deformation direction (R1). [8] Battery cell (1) according to one of the preceding claims, wherein the first zone (6) and the second zone (7) have different second deformation resistances in a second deformation direction (R2) which is perpendicular to the housing base (3), wherein the first zone (6) has a higher second deformation resistance in the second deformation direction (R2) than the second zone (7). [9] Battery cell (1) according to one of the preceding claims, comprising two of the second zones (7) which connect to the first zone (6) at opposite ends of the first zone (6). [10] Battery cell (1) according to one of the preceding claims, wherein in the first zone (6) the sheet (4) has a greater thickness than in the second zone (7). [11] Battery cell (1) according to any of the preceding claims, wherein the sheet (4) extends to or beyond the edges of a bottom surface of the active material (5).

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