Battery cell, cell stack and method for manufacturing a cell housing for a battery cell

Abstract

The invention relates to a preferably prismatic battery cell with a cell housing (1), in particular a cuboid-shaped one, which has two flat walls (3) lying opposite one another in a transverse direction (y) of the housing, wherein the two flat walls (3) are connected to side walls (5) lying opposite one another in the longitudinal direction (x) of the housing and to bottom and top walls (7, 9) lying opposite one another in the vertical direction (z). According to the invention, the cell housing (1) is extended on one or both sides with a housing pocket (21) which delimits a cavity (17) which is preferably at least partially filled with a functional material (25), such as a functional foam or flame-retardant material.

Description

[0001] The invention relates to a preferably prismatic battery cell according to the preamble of claim 1, a cell stack or cell assembly for a high-voltage battery system according to claim 9 and a method for producing a cell housing for a battery cell according to claim 10.

[0002] In a state-of-the-art cell assembly for a high-voltage battery system, prismatic lithium-ion battery cells are stacked one behind the other in the stacking direction under mechanical prestress. Depending on the cell chemistry, either elastic intermediate layers as flexible compression pads or strips (1 to 2 mm) are placed between the battery cells to compensate for swelling forces during charging cycles and aging. Alternatively, significantly thicker (2 to 5 mm) anti-propagation pads are placed between the battery cells to thermally insulate neighboring cells in the event of thermal runaway of a battery cell and to compensate for swelling forces during charging cycles and aging. Such cell intermediate pads are based on aerogel / ceramic flow mats or on silicone foams laminated into plastic films.

[0003] In the current state of the art, the cell interlayer pads are stored as individual parts that are positioned between the battery cells during the stacking process. Accordingly, the manufacturing process for producing the cell assembly is complex in terms of components and manufacturing technology.

[0004] DE 10 2022 104 370 A1 discloses a battery cell unit comprising a battery cell, a cell housing, and a cell chemistry unit arranged in the cell housing. A first width in a first direction is assigned to the battery cell unit, at least in a specific operating position. The battery cell unit has at least one first functional layer that is at least partially compressible in the first direction, is arranged fixedly with respect to the battery cell and next to the cell chemistry unit with respect to the first direction, and is designed to compensate for the expansion of the cell chemistry unit in the first direction, in such a way that the battery cell unit does not exceed the first width assigned to it in the specific operating position.DE 10 2021 208 931 A1 discloses a battery cell comprising a prismatic battery cell housing and at least one electrode unit accommodated in the prismatic battery cell housing. An intermediate space is provided between the prismatic battery cell housing and the at least one electrode unit, which is at least partially filled with a filler element. DE 20 2019 101 373 U1 discloses a battery rack for accommodating a lithium-ion accumulator module comprising prismatic lithium-ion cells. The battery rack comprises a housing providing a receiving space for the accumulator module, which housing is open at the front, a base part, a cover part, and two side parts connecting the base part to the cover part. Furthermore, the battery rack comprises a separating plate arranged at a distance from the cover part, leaving a gap.

[0005] The object of the invention is to provide a preferably prismatic battery cell that offers increased functionality compared to the prior art. In particular, the component and manufacturing costs for producing a cell assembly consisting of battery cells stacked one behind the other are to be reduced.

[0006] The object is solved by the features of claim 1, 9 or 10. Preferred developments of the inventions are disclosed in the subclaims.

[0007] The invention relates to a preferably prismatic battery cell with a particularly cuboid-shaped cell housing. The cell housing has two flat walls opposite one another in a transverse direction of the housing. The two flat walls are connected to side walls opposite one another in the longitudinal direction of the housing and to bottom and top walls opposite one another in the vertical direction of the housing. According to the characterizing part of claim 1, the cell housing is extended on one or both sides and made of the same material and in one piece with a housing pocket. The housing pocket delimits a hollow space. This can preferably be at least partially filled with a functional material, such as a functional foam or a flame-retardant material. Alternatively, the hollow space can also remain unfilled. The housing pocket integrated into the cell housing can assume the function of a conventional cell intermediate pad in the cell assembly.In contrast to conventional cell intermediate pads, however, the housing pocket is made of the same material and is integrated in one piece into the cell housing of the battery cell, which greatly reduces the component and manufacturing costs involved in producing a cell assembly.

[0008] In the cell stack, a number of battery cells are stacked one behind the other in a stacking direction under mechanical prestress. The housing pockets are located in the force path created by the mechanical prestress. Accordingly, the housing pocket in the cell stack can act like a compression pad, compensating for volume expansion of the battery cells due to swelling or aging. Furthermore, the housing pocket can be designed to be elastically flexible, if necessary by adjusting the wall thicknesses.

[0009] For example, the housing pocket in the cell stack can act as a spacer between adjacent battery cells in the cell stack. Alternatively and / or additionally, the housing pocket can act as a stiffening element that increases the component rigidity of the cell housing of the battery cell. Furthermore, the housing pocket, especially if filled with air, can act as thermal insulation between adjacent battery cells in the cell stack.

[0010] In a specific embodiment, the housing pocket can be realized as follows: At least one of the two flat walls of the cell housing can be double-walled, with an inner wall delimiting the interior of the cell housing and an outer wall spaced across the cavity, for example in the transverse direction of the housing. The inner wall and the outer wall can be substantially congruent and, in particular, can be designed with the same wall height (in the vertical direction of the housing) and the same wall width (in the longitudinal direction of the housing). To further increase functionality, the air-filled cavity of the housing pocket can be designed so that coolant flows through it. For example, the cavity of the housing pocket can be open on both sides in the longitudinal direction of the housing, whereby coolant, such as cooling air, can flow through it, for example by forced convection.According to the invention, the inner wall of the housing pocket defines the interior of the cell housing, which is hermetically sealed to the outside, particularly to the housing pocket, via the inner wall. Alternatively to the embodiment described above, the cavity of the housing pocket can also be completely closed to the outside.

[0011] In a further embodiment, the cavity can be divided into sub-cavities by means of at least one support web. The support web can be connected to both the inner and outer walls of the housing pocket. The sub-cavities can be filled with various functional materials. The support web can, for example, increase the component rigidity of the battery cell in the transverse direction of the housing, in which the mechanical prestress acts in the cell stack.

[0012] From a process engineering perspective, it is simple if the cell housing is manufactured by extrusion, particularly aluminum extrusion. In this case, in a first process step, an intermediate cell housing product is cut to length from an extruded profile. In the intermediate cell housing product, the base and cover walls, the flat walls, and the housing pocket are integrated from the same material and in one piece. In a subsequent second process step, the interior of the cell housing can be equipped with an electrode / separator arrangement. In a third process step, the side walls can be mounted as separate components onto the still open sides of the intermediate cell housing product, thus completing the cell housing.

[0013] As an alternative to extrusion, the cell housing can also be manufactured using a folding process. First, a flat sheet metal blank is prepared, which, when unfolded, contains the housing walls. The sheet metal blank is folded into the cell housing using a forming process. In another process alternative, the housing walls of the cell housing can be stored as individual parts, which are then joined together in a welding process to form the cell housing. For example, the housing pocket can be prefabricated as a separate component. The separate housing pocket can then be connected to the cell housing or the cell housing intermediate product using a joining process, particularly a welding process.

[0014] In a further embodiment, the housing pocket projects beyond a cell housing top wall and / or a cell housing bottom wall by an excess amount, so that the wall height of the housing pocket is greater than the wall height of the cell housing inner wall. Furthermore, in one embodiment, the cell housing can have a housing pocket whose cavity is open on both sides, i.e., upwards and downwards, not in the longitudinal direction of the housing, but rather in the vertical direction of the housing.

[0015] As mentioned above, the cell housing intermediate product can be folded in a folding process, specifically from a sheet metal blank that is folded in a meandering manner around parallel folding axes. The folding axes form the longitudinal edges of the housing running in the longitudinal direction of the housing. The meandering fold separates the cell housing interior from the cavity of the housing pocket via the inner wall. The end edges of the sheet metal blank, which run parallel to the longitudinal edges of the housing, can each be welded to the inner wall in a welding process. Subsequently, the cover assemblies, which are kept as separate components, are mounted onto the still open sides of the cell housing intermediate product, thus completing the cell housing.

[0016] In a further process sequence for producing a cell housing intermediate product, in a first process step a cell housing intermediate product can be cut to length from an extrusion profile that has been produced in an extrusion process. Viewed in cross-section, the cell housing intermediate product can be U-profile-shaped with the bottom wall and with lateral housing pockets or flat walls extending upwards from it. At this point in the process, the two lateral housing pockets or flat walls are still spread apart laterally. In addition, the two housing pockets or flat walls can end at the top with cover wall webs that protrude inwards at right angles. A loading opening is formed between the two cover wall webs, through which the electrode / separator arrangement is inserted into the interior of the cell housing in a placement process. This is followed by a forming step in which the two housing pockets orThe flat side walls are moved toward each other using joining forces, bringing the top wall webs into weldable contact. In a final welding process, the two top wall webs can be welded together to form the cell housing intermediate product. The cover assemblies, which were kept as separate components, are then mounted onto the still open sides of the cell housing intermediate product, completing the cell housing.

[0017] Exemplary embodiments of the invention are described below with reference to the accompanying figures. They show: Fig. 1 to 7d different views of the battery cell according to the invention; and Fig. 8a to 11c show further embodiments of the invention.

[0018] In the Fig. 1 shows a prismatic battery cell in isolation. Its cuboid-shaped cell housing 1 has two flat walls 3 opposite each other in a transverse housing direction y. The two flat walls 3 are connected to side walls or cover assemblies 5 opposite each other in the longitudinal housing direction x, as well as to bottom and cover walls 7, 9 opposite each other in the vertical housing direction z. Each of the cover assemblies 5 consists of a cell terminal 11 and a cover plate 13.

[0019] The Fig. The right-hand flat wall of the cell housing 1 is double-walled, with an inner wall 15 defining the interior of the cell housing and an outer wall 19 spaced from the inner wall 15 in the transverse housing direction y by a cavity 17. This creates a housing pocket 21 whose cavity 17 is open on both sides in the longitudinal housing direction x. The inner wall 15 and the outer wall 19 of the housing pocket 21 are congruent and have the same wall height Δz and the same wall width Δy.

[0020] By providing the housing pocket 21, the functionality of the cell housing 1 is increased. For example, the air-filled housing pocket 21 acts as a spacer or as a heat insulating element between adjacent battery cells of a cell assembly or cell stack 23, as shown in the Fig. 2. In the cell assembly 23 are a number of battery cells which are identical in construction to the Fig. 1 shown battery cell are arranged one behind the other in a stacking direction and in the stacking direction with mechanical prestress F V The housing pockets 21 of the battery cells installed in the cell assembly 23 are in the force path of the mechanical preload F V positioned. Furthermore, the housing pockets 21 are designed to be sufficiently elastically flexible. The housing pockets 21 can therefore act as compression pads that compensate for volume expansion of the battery cells due to the swelling effect or aging. Furthermore, coolant, e.g., cooling air, can flow through the housing pockets 21 of the battery cells to cool the cell stack 23.

[0021] Alternatively, the Fig. 3 shows a cell stack 23 in which the cavity 17 of the housing pockets 21 is each filled with a flame-retardant material 25. In this case, the housing pockets 21 act both as spacers and as flame retardants in the event of thermal runaway of one of the battery cells.

[0022] In the Fig. 4 shows another cell stack 23 which is essentially identical in construction to the one in Fig. 3 shown cell cluster 23 is constructed. In contrast to the Fig. 3 are in the Fig. 4, the housing pockets 21 of the battery cells stacked in the cell assembly 23 are filled with air, while an additional cell intermediate pad 27 is positioned between each battery cell as a separate housing component. The air-filled housing pockets 21 act as thermal insulation elements and compression pads, while the cell intermediate pads 27 act as flame retardants.

[0023] Based on the Fig. 5, a manufacturing process for producing the cell housing 1 is described below. Accordingly, in a first process step, a cell housing intermediate product 29 is cut to length from an extrusion profile 31 that has been produced in an extrusion process. The bottom and top walls 7, 9, the two flat walls 3 and the housing pocket 21 are integrated in the cell housing intermediate product 29 as a single piece of material. In a second process step, not shown, the cell housing interior of the cell housing intermediate product 29 is coated with a (only in the Fig. 10, Fig. 11b and Fig. 11c) is assembled. Subsequently, the cover assemblies 5, which are kept as separate components, are mounted on the still open sides of the cell housing intermediate product 29, thus completing the cell housing 1.

[0024] In the Fig. 6 shows the battery cell according to the invention in a further embodiment. In contrast to Fig. 1 is in the Fig. 6, the battery cell is provided with a housing pocket 21 on each side in the housing transverse direction y. Accordingly, the two flat walls 3 are each double-walled with an inner wall 15, an outer wall 19, and an intermediate cavity 17.

[0025] In the Fig. 7a to 7d show different versions of the cell housing 1. In the Fig. 7a, the cell housing 1 has a housing pocket 21 on both sides in the housing transverse direction y, as is also the case in the Fig. 6 is the case. The same applies to the Fig. 7b shown cell casing 1. As can be seen from the Fig. As can be seen from Figure 7b, the outer walls 19 of the two housing pockets 21 terminate upwards and downwards in the vertical direction z of the housing, each with rounded ends which are connected to the upper and lower ends of the cell housing inner wall 15.

[0026] In the Fig. 7c, the cell housing 1 is formed with a housing pocket 21 on one side in the housing transverse direction y. The cavity 17 of the housing pocket 21 is divided into two separate partial cavities by a support web 33. These can be filled with different filling materials if necessary.

[0027] In the Fig. 7d, the cell housing 1 is also formed on one side with a housing pocket 21. The cavity 17 of the pocket is divided into a total of four partial cavities by means of support webs 33. The support webs 33 can increase the component rigidity of the cell housing 1 in the housing transverse direction y, in which the mechanical prestress F V in cell network 33.

[0028] In the Fig. 8a and Fig. 8b shows further embodiments. Their structure and function essentially correspond to the structure and function of the previous embodiments. Fig. 8a is analogous to Fig. 6 the battery cell is provided with a housing pocket 21 on both sides in the housing transverse direction y. In contrast to Fig. 6 dominate in the Fig. 8a the two housing pockets 21 the cell housing cover wall 9 by an excess, so that the wall height Δz2 of the housing pockets 21 is larger than the wall height Δz1 of the cell housing inner wall 15. The same also applies to the embodiment of the Fig. 8b, in which the two housing pockets 21 project beyond both the cell housing top wall 9 and the cell housing bottom wall 7 by an excess amount.

[0029] The Fig. 9 shown cell housing 1 has - analogous to the embodiment of the Fig. 1 - only has a housing pocket 21 on the right side of the housing. In contrast to the Fig. 1 is, however, in the Fig. 9 the cavity 17 of the housing pocket 21 is not designed to be open in the housing longitudinal direction x, but rather in the housing vertical direction z on both sides, that is to say upwards and downwards.

[0030] In the Fig. 10, a cell housing intermediate product 29 is made from a folded sheet metal blank, which is folded in a meandering manner around parallel folding axes F in a folding process. The folding axes F form in the Fig. 10 the longitudinal edges of the housing running in the longitudinal direction x. Due to the meandering fold, the cell housing interior, in which Fig. 10, an electrode / separator arrangement 37 is inserted, separated from the cavity 17 of the housing pocket 21 via the inner wall 15. The end edges 39 of the sheet metal blank, which run parallel to the longitudinal edges of the housing, can each be welded to the inner wall 15 in a welding process. Subsequently, the cover assemblies 5, which are kept as separate components, are mounted on the still open housing sides of the cell housing intermediate product 29, thus completing the cell housing 1.

[0031] In the Fig. 11a to 11c illustrate a further process sequence for the production of a cell casing intermediate product 29. Accordingly, in a first process step ( Fig. 11a) a cell housing intermediate product 29 is cut to length from an extrusion profile that has been produced in an extrusion process. The cell housing intermediate product 29, viewed in cross-section, is U-shaped with the bottom wall 7 and with lateral housing pockets 21 raised therefrom. Fig. In the intermediate cell housing product 29 shown in Figure 11a, the two housing pockets 20 are spread apart laterally. Furthermore, the two housing pockets 21 are terminated at the top by cover wall webs 41, which project inward at right angles. A loading opening 43 is formed between the two cover wall webs 41, through which the cells are loaded in a loading process ( Fig. 11b) the electrode / separator assembly 37 is inserted into the cell housing interior. This is followed by a forming step in which the two housing pockets 21 are joined together with joining forces F Fare moved toward each other, whereby the cover wall webs 41 come into weldable contact with each other. In a final welding process, the two cover wall webs 41 are welded together to form the cell housing intermediate product 29. Subsequently, the cover assemblies 5, which are kept as separate components, are mounted on the still open housing sides of the cell housing intermediate product 29, thus completing the cell housing 1. List of reference symbols 1 cell housing 3 flat wall 5 Cover assembly 7, 9 floor and ceiling wall 11 Cell terminal 13 Cover plate 15 Interior wall 17 Cavity 19 Exterior wall 21 Case bag 23 Cell group 25 Flame retardant material 27 Cell intermediate pad 29 Cell casing intermediate 31 Extrusion profile 33 Support bridge 35 cavity 37 Electrode / separator arrangement 39 end edges 41 Deck wall bridge 43 Loading opening F V mechanical preload F folding axes F F Joining force Δz, Δz1, Δz2 wall heights 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 104 370 A1

[0004] DE 10 2021 208 931 A1

[0004] DE 20 2019 101 373 U1

[0004]

Claims

[1] Battery cell, in particular prismatic battery cell with a preferably cuboid cell housing (1) which has two flat walls (3) opposite one another in a housing transverse direction (y), wherein the two flat walls (3) are connected to side walls (5) opposite one another in the housing longitudinal direction (x) and to bottom and top walls (7, 9) opposite one another in the housing vertical direction (z), characterized by that the cell housing (1), for example in the housing transverse direction (y), is extended on one or both sides with a housing pocket (21) which delimits a cavity (17), and that in particular the cavity (17) is filled with air and / or is at least partially filled with a functional material (25), such as a functional foam or flame-retardant material. [2] Battery cell according to claim 1, characterized bythat the battery cell is part of a cell stack (23) in which a number of battery cells are arranged in a stacking direction under mechanical prestress (F V ) are stacked one behind the other, and in particular that the housing pocket (21) in the cell stack (23) acts like a compression pad which compensates for a volume expansion of the battery cells due to a swelling effect or due to aging. [3] Battery cell according to claim 2, characterized by that the housing pocket (21) acts as a spacer between adjacent battery cells in the cell stack (23), and / or that the housing pocket (21) acts as a stiffening element which increases the component stiffness of the cell housing (1) of the battery cell, and / or that the housing pocket (21) acts as a thermal insulation between adjacent battery cells in the cell stack (23). [4] Battery cell according to one of the preceding claims, characterized byin that, in order to provide the housing pocket (21), at least one of the cell housing walls is double-walled, with an inner wall (15) delimiting the cell housing interior and an outer wall (19) spaced therefrom, for example in the housing transverse direction (y), in the housing longitudinal direction (x) or in the housing vertical direction (z), via the cavity (17), and in particular the inner wall (15) hermetically seals the cell housing interior from the housing pocket (21). [5] Battery cell according to one of the preceding claims, characterized bythat the inner wall (15) and the outer wall (19) are substantially congruent and in particular are designed with the same wall height (Δz) and the same wall width (Δx), and / or that the cavity (17) of the housing pocket (21) is open on both sides, for example in the housing longitudinal direction (x) or in the housing vertical direction (z), i.e. in particular cooling air or other coolant can flow through it and / or can be easily equipped with the functional material (25) in terms of production technology, and / or that the inner wall (15) and the outer wall (19) are designed with different wall heights (Δz1, Δz2), and / or that the cavity (17) of the housing pocket (21) is completely closed to the outside. [6] Battery cell according to one of the preceding claims, characterized bythat the cavity (17) is divided into partial cavities by means of at least one supporting web (33), that the supporting web (33) is connected to both the inner wall (15) and the outer wall (19) of the housing pocket (21) in a force-transmitting manner, and that in particular the partial cavities can be filled with different functional materials (25), and / or that the supporting web (33) increases the component rigidity of the battery cell in the housing transverse direction (y) in which the mechanical prestress (F V ) in the cell stack (23). [7] Battery cell according to one of the preceding claims, characterized bythat the cell housing (1) can be produced by means of extrusion, in particular aluminum extrusion, or that the cell housing (1) is manufactured in a folding process and / or is constructed from individual parts which are joined together in welding processes, and that in particular the housing pocket (21) can be prefabricated as a separate component and can be connected to the cell housing (1) or the cell housing intermediate product (29) in a joining process, in particular a welding process. [8] Battery cell according to claim 7, characterized by , that - in a first process step, a cell housing intermediate product (29) is cut to length from an extrusion profile (31) produced during extrusion, and in that in the cell housing intermediate product (29), the bottom and top walls (7, 9), the flat walls (3) and the housing pocket (21) are integrated in one piece from the same material, and - in a second process step, the cell housing interior is equipped with an electrode / separator arrangement, and - in a third process step, the side walls (5) can be connected as separate components to the still open housing sides of the cell housing intermediate product (29) to form the cell housing (1). [9] Cell stack (23) for a high-voltage battery system with a number of battery cells stacked one behind the other in the stacking direction, of which at least one battery cell is a battery cell according to one of claims 1 to 8. [10] Method for manufacturing a cell housing (1) for a battery cell according to one of claims 1 to 8.

Images