Prismatic battery cell and method for producing such a battery cell

Abstract

The invention relates to a prismatic battery cell having a cuboid cell housing (1), in which at least one electrode / separator arrangement (15) is arranged. According to the invention, the cell housing (1) is produced in a folding process which comprises a provision step, in which a sheet metal blank (17) is able to be provided in developed form with cell housing walls (3, 5, 7), and a forming step, in which the cell housing walls (3, 5, 7) are bent at predetermined bending lines, specifically so as to form the cell housing (1) or a cell housing intermediate product (19).

Description

[0001] Description

[0002] Prismatic battery cell and methods for manufacturing such a battery cell

[0003] The invention relates to a prismatic battery cell according to the preamble of claim 1 and to a method for manufacturing such a battery cell according to claim 10.

[0004] A typical prismatic battery cell for a high-voltage battery system has a rigid, cuboid-shaped metal cell housing in which an electrode / separator assembly is arranged. The electrode / separator assembly is electrically connected to cell terminals via current collectors. Current is drawn from the battery cell at the two cell terminals.

[0005] In the prior art, the battery cell housing is manufactured from a cell cup, which is produced from a metal blank using a deep-drawing process. The open end of the cell cup housing is closed with a lid assembly to which the electrode / separator arrangement is pre-mounted. Such a process sequence involves a comparatively high manufacturing effort.

[0006] From CN 110828714 A, a battery cell is known with a cell casing formed by bending a sheet of metal at least once, with two ends of the bent sheet abutting to form a hollow cylindrical structure. From US 2022 / 0149461 A1, a prismatic battery cell is known, the battery casing of which comprises a main casing body with a cuboid shape and a lid connected to the main casing body to close its opening. Another lithium-ion battery cell is known from CN 101369674 A.

[0007] The object of the invention is to provide a prismatic battery cell and a method for manufacturing such a battery cell in which the cell housing is easier to manufacture compared to the prior art and / or has increased functionality.

[0008] The problem is solved by the features of claim 1 or 10. Preferred embodiments of the invention are disclosed in the dependent claims. The invention relates to a prismatic battery cell with a cuboid cell housing in which at least one electrode / separator arrangement is arranged. According to the characterizing part of claim 1, the cell housing is manufactured in a folding process. The folding process comprises a preparation step in which a flat sheet metal blank with integrated cell housing walls is provided. In a subsequent forming step, the cell housing walls are bent along predetermined bending lines, forming the cell housing or a cell housing intermediate.

[0009] The completed cuboid cell housing has two flat walls opposite each other in a transverse direction. These are connected by a bottom wall and a top wall. The housing sides opposite each other in a longitudinal direction are each closed by a cover assembly. The cover assembly consists of several parts: a cover plate with a cell terminal mounted to it, which is electrically connected to the electrode / separator assembly.

[0010] In one initial design variant, the flat sheet metal blank can consist of the two flat walls, the bottom wall, and the top wall. In contrast, the cover assembly can be a separate component from the flat sheet metal blank.

[0011] In the folding process, the unfolded material is folded into a cell housing intermediate, forming a hollow profile with a closed cross-section. The two free ends of the unfolded material are firmly connected to each other, primarily via a weld. Viewed along its longitudinal axis, the cell housing intermediate has open sides on both sides. In an assembly process, the electrode / separator assembly is inserted into the cell housing intermediate.

[0012] The open housing sides of the cell housing intermediate product are then closed with the lid assemblies.

[0013] As an alternative to the welding connection mentioned above, the two unfolded ends can also be connected to each other via a snap / lock connection.

[0014] In a first embodiment, the weld seam connecting the two unfolded ends can be positioned centrally between the longitudinal edges of the cell housing in the transverse direction. Alternatively, in a second embodiment, the weld seam can run directly along a longitudinal edge of the cell housing.

[0015] In another embodiment, the cover plate of the cover assembly, together with the flat, bottom, and top walls, can form a single, material-integrated component of the developed piece. In this case, the cover plate can be integrally formed with a vertical edge of one of the flat walls. Alternatively, the cover plate can be integrally formed with a transverse edge of the bottom or top wall.

[0016] In another embodiment, the cell housing can be designed with a rupture membrane, preferably positioned on the bottom or top wall. To reduce component size, the rupture membrane can be implemented as a closed-surface indentation, formed integrally and in one piece with a cell housing wall, using a single material. The indentation can have a significantly reduced wall thickness compared to the adjacent wall section.

[0017] To further enhance functionality, ribs are embossed into the cell housing walls. These can serve various functions, particularly increasing the stiffness of the cell housing to prevent volume expansion during charging due to swelling or aging. Alternatively and / or additionally, at least one of the ribs can act as a movement stop. This movement stop can be set back from a free edge of the open side of the cell housing intermediate by a longitudinal offset. In the assembled state, the lid assembly is in contact with the movement stop. Furthermore, the lid assembly is welded to the cell housing intermediate, forming the completed cell housing.Preferably, the longitudinal offset should correspond approximately to the sheet thickness of the cover plate, which, in the assembled state, is in contact with the groove serving as a movement stop. In this case, the cover plate of the cover assembly is flush with the open housing side of the cell housing intermediate.

[0018] Examples of implementation are described below with reference to the attached figures.

[0019] Figures 1 to 10c show different embodiments of the cell casing according to the invention.

[0020] Figure 1 shows a cuboid cell housing 1 of a prismatic battery cell according to the invention in its assembled state. Accordingly, the cuboid cell housing 1 has two opposing flat walls 3 in a transverse direction y, of which only one flat wall 3 is shown in Figure 1. The flat walls 3 are connected to each other via a bottom wall 5 and a top wall 7. The housing sides opposite each other in a longitudinal direction x are each closed with a cover assembly 9. Each of the two cover assemblies 9 is formed in multiple parts, consisting of a cover plate 11 with a cell terminal 13 mounted thereon for an external current tap. The cell terminals 13 are electrically connected to an electrode / separator arrangement 15 located inside the cell housing (indicated only in Figure 3a). In Figure 1, each of the two flat walls 3 transitions into the top wall 7 and the bottom wall 5 at longitudinal edges 25 of the housing.Furthermore, the two flat walls 3 transition into the two cover assemblies 9 at housing vertical edges 27, while the bottom and top walls 7 transition into the cover assemblies 9 at housing transverse edges 29.

[0021] A key aspect of the invention is that the cell housing 1 is manufactured using a folding process. The folding process essentially comprises two process steps: a preparation step in which a flat sheet metal blank 17 (Figure 2a) is provided, containing cell housing walls in their unfolded form. In the embodiment shown in Figure 2a, the flat sheet metal blank 17 includes the two flat side walls 3, the bottom wall 5, and the top wall 7. The two cover assemblies 9, however, are separate components from the sheet metal blank 17. In a subsequent forming step, the folding process is carried out, in which the cell housing walls 3, 5, 7 are folded along predetermined bending lines or along their longitudinal, vertical, and transverse edges 25, 27, 29, forming an intermediate cell housing product 19, which is indicated, for example, in Figure 8.The cell housing intermediate 19 is a hollow profile with a cross-section yz, in which the two free developed ends 21 (Figure 2a) of the sheet metal blank 17 are firmly connected to each other by a weld 23. In Figure 1 or 2c, the weld 23 is positioned centrally between the two longitudinal edges 25 of the housing in the transverse direction y.

[0022] As further shown in Figure 8, the cell housing intermediate 19, viewed in the longitudinal direction x, has one open side on each side. In the subsequent assembly process, the electrode / separator assembly 15 is inserted into the cell housing intermediate 19. The open sides of the cell housing intermediate 19 are then closed with the cover assemblies 9. The cover plates 11 of the cover assemblies 9 are welded to the cell housing intermediate 19.

[0023] In the embodiment shown in Figure 3a, the electrode / separator assembly 15 is pre-positioned on a flat wall 3 of the flat sheet metal blank 17. Its conductor tabs are electrically connected to the cell terminals 13 of the cover assemblies 9. The cover plates 11 of the two cover assemblies 9 are not a single, integral part of the flat sheet metal blank 17.

[0024] As an example, in the assembly process, the electrode / separator assembly 15 with the two attached cover assemblies 9 can be inserted into the cell housing intermediate product 19. The cover assemblies 9 can then be welded to the cell housing intermediate product 19, as indicated in Figure 3d. In contrast to the previous embodiment, in Figure 3c the weld seam 23 connecting the two unfolded ends 21 is no longer positioned centrally between the cell housing longitudinal edges 25, but rather runs directly along the cell housing longitudinal edge 25.

[0025] In the embodiment shown in Figure 4a, a flat sheet metal blank 17 is also shown in its developed state. Accordingly, the cover assemblies 9, together with the flat, bottom, and top walls 3, 5, 7, are integral components of the sheet metal blank 17, made of the same material. In Figure 4a, each of the cover plates 11 is formed on a vertical edge 27 of one of the flat walls 3 of the cell housing. The weld seam 23 connecting the developed ends 21 is positioned directly on a longitudinal edge 25 of the housing, as shown in Figure 4c.

[0026] Figure 5a shows an embodiment in which the cover plates 11 of the two cover assemblies 9 are also integrally formed directly on a cell housing vertical edge 27 of one of the flat walls 3. In contrast to the previous embodiment, the two developed ends 21 are not connected to each other via the weld seam 23, but rather via a snap / lock connection 31 (Figure 5c).

[0027] In Figure 6a, the plates 11 of the two cover assemblies 9 are also formed as a single, integral part of the sheet metal blank 17. In contrast to the previous embodiment, in Figure 6a each of the cover plates 11 is integrally formed on a transverse edge 29 of the cell housing, either on the bottom wall 5 or the top wall 7. The weld seam 23 is positioned centrally between two longitudinal edges 25 of the top wall 7, as shown in Figure 6c.

[0028] Figures 7a to 7c each show battery cells in whose flat walls three beads 33 are embossed. These increase the stiffness of the cell housing 1. In Figure 7a, a number of narrow beads 33 are embossed, running parallel to each other at a distance along the vertical direction z of the housing. In Figure 8b, beads 33 are also embossed, but with a wider bead width compared to Figure 7a. In Figure 7c, the beads 33 are arranged crosswise in the flat wall 3.

[0029] Figure 9 shows a section of the cell casing 1 in which a rupture membrane 35 is formed. According to Figure 9, the rupture membrane 35 is realized as a closed-surface indentation with a reduced wall thickness compared to the adjacent wall section. The closed indentation is formed integrally with the cell casing wall and is made of a single material.

[0030] In Figure 8, a groove formed in the flat wall 3 acts as a movement stop 37. This stop is set back in the longitudinal direction x of the housing by a longitudinal offset Ax from a free edge 39 of the open housing side of the cell housing intermediate 19. In the assembled state (not shown), the cover plate 11 of the cover assembly 9 is not in contact with the free edge 39 of the cell housing intermediate 19, but rather with the movement stop 39. The cover plate 11 is welded to the cell housing intermediate 19 in the assembled state.

[0031] Figures 10a to 10c show the structure of a cover assembly 9 in different views. Accordingly, the cover assembly 9 is composed of several parts: a rivet plate 41, a rivet head 43, a frame 45, an insulating plate 47, and the cell terminal 13. Figure 10c shows a component set 40, in which the components of the cover assembly 9 are indicated separately. Reference numeral list

[0032] Cell casing

[0033] flat wall

[0034] floor wall

[0035] Ceiling wall

[0036] Cover assembly

[0037] Cover plate

[0038] Cell terminal

[0039] Electrode / separator arrangement

[0040] Sheet metal cutting

[0041] Cell casing intermediate

[0042] End of settlement

[0043] weld

[0044] Housing - Long edge

[0045] Case vertical edge

[0046] Case cross edge

[0047] Snap / lock connection

[0048] bead

[0049] Burst membrane

[0050] Motion stop free edge

[0051] Component set

[0052] Rivet plate

[0053] rivet head

[0054] Frame

[0055] I insulating plate 47 Ax longitudinal offset

Claims

Patent claims 1. Prismatic battery cell with a cuboid cell housing (1) in which at least one electrode / separator arrangement (15) is arranged, characterized in that the cell housing (1) is manufactured in a folding process which has a provisioning step in which a sheet blank (17) in unfolded form with cell housing walls (3, 5, 7) can be provided, and a forming step in which the cell housing walls (3, 5, 7) are bent at predetermined bending lines, forming the cell housing (1) or a cell housing intermediate product (19).

2. Prismatic battery cell according to claim 1, characterized in that the cuboid cell housing (1) has two flat walls (3) opposite each other in a housing transverse direction (y) which are connected to each other via a bottom wall (5) and a top wall (7), that the housing sides opposite each other in a housing longitudinal direction (x) are closed by a cover assembly (9) each, and that in particular the cover assembly (9) is formed from a cover plate (11) with a cell terminal (13) mounted thereon, which is in electrical connection with the electrode / separator arrangement (15).

3. Prismatic battery cell according to claim 2, characterized in that the sheet metal blank (17) consists of the two flat walls (3) as well as the bottom wall (5) and the top wall (7), and in particular that the lid assembly (9) is a component separate from the sheet metal blank (17).

4. Prismatic battery cell according to claim 3, characterized in that in the folding process the sheet metal blank (17) is foldable to form a cell housing intermediate product (19) which forms a hollow profile closed in cross-section (yz) in which the two free unfolded ends (21) are firmly connected to each other, in particular via a weld seam (23), that the cell housing intermediate product (19) has housing sides open on both sides in the longitudinal direction (x), and that the electrode / separator arrangement (15) can be inserted into the cell housing intermediate product (19), and subsequently the open housing sides of the cell housing intermediate product (19) can be closed with the cover assemblies (9).

5. Prismatic battery cell according to claim 4, characterized in that the weld seam (23) connecting the two unfolded ends (21) is located centrally between the longitudinal edges (25) of the cell housing (1) in the transverse direction (y) of the housing, or that the weld seam (23) runs directly along a longitudinal edge (25) of the cell housing.

6. Prismatic battery cell according to claim 3, 4 or 5, characterized in that the cover plate (11) of the cover assembly (9) together with the flat, bottom and top walls (3, 5, 7) is a single-material and one-piece component of the sheet metal blank (17), in particular that the cover plate (11) is formed on a cell housing vertical edge (27) of one of the flat walls (3), or in particular that the cover plate (11) is formed on a cell housing transverse edge (29) of the bottom wall (5) or the top wall (7).

7. Prismatic battery cell according to one of claims 4 to 6, characterized in that the two unfolded ends (21) can be connected to each other during the folding process via a snap / lock connection (31).

8. Prismatic battery cell according to one of the preceding claims, characterized in that the cell housing (1) is formed with a burst membrane (35), and that the burst membrane (35) is a closed-surface indentation which is formed in the cell housing wall in a single piece and is made of a single material and has a reduced wall thickness compared to the adjacent wall section.

9. Prismatic battery cell according to one of the preceding claims, characterized in that grooves (33) are embossed in the cell housing walls (3, 5, 7) which fulfill different functions, in particular increasing the component stiffness of the cell housing (1), that in particular at least one of the grooves acts as a movement stop (37) which is set back in the longitudinal direction (x) of the housing by a longitudinal offset (Ax) from a free edge (39) of the open housing side of the cell housing intermediate product (19), and that in the assembled state the cover assembly (9) is in contact with the movement stop (37) and is welded to the cell housing intermediate product (19).

10. Method for manufacturing a prismatic battery cell according to one of the preceding claims.

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