Process for producing a battery cell casing with overpressure reduction means, battery cell casing and battery cell

Abstract

The invention relates to a process (38) for producing a battery cell casing (10) for a battery cell (12), comprising the steps of: forming an internal volume (14) at least partly delimited by several casing walls (16) connected to one another in one piece; and introducing (40) overpressure reduction means (20) for reducing an overpressure in the internal volume (14) to prevent uncontrolled rupture of the battery cell casing (10), the overpressure reduction means being introduced in one piece into at least a first casing wall (18), having a first material thickness (D1), of the casing walls (16) by at least a first machining process (42), which forms a rupturing structure (22) in the first casing wall (18) and at least partly reduces the material thickness of the rupturing structure (22) to a second material thickness (D2) smaller than the first material thickness (D1). The invention further relates to a battery cell casing (10) and to a battery cell (12).

Description

[0001] Method for manufacturing a battery cell housing with overpressure relief medium, as well as battery cell housing and battery cell

[0002] Description introduction

[0003] The invention relates to a method for manufacturing a battery cell housing according to claim 1. The invention further relates to a battery cell housing and a battery cell.

[0004] German patent DE 102022 115428 B3 describes a battery cell with a battery cell housing enclosing an inner volume and with housing walls made of steel. A rectangular degassing opening for venting gases from the inner volume is provided on a narrower housing wall and is sealed with a foil.

[0005] The object of the present invention is to make the battery cell safer and more reliable. The influence of tolerances on the safety of the battery cell is to be reduced. The battery cell housing is to be made more cost-effective.

[0006] At least one of these problems is solved by a manufacturing process with the features of claim 1. This allows the overpressure in the internal volume to be reduced more precisely and reliably. The battery cell housing can be manufactured more cost-effectively.

[0007] The battery cell casing can accommodate an electrode array for providing electrical energy to the battery cell. The battery cell can consist of at least the battery cell casing and the electrode array. The battery cell casing can be made of metal, in particular steel or aluminum, plastic, and / or a composite material. The battery cell casing can be made of sheet metal. The battery cell casing can be prismatic or cylindrical in shape.

[0008] The first casing wall can be rectangular, for example, square. All subsequent casing walls of the battery cell casing can be rectangular. The first casing wall can be smaller than the largest casing wall of the battery cell casing.

[0009] The internal volume can be formed by a forming process, such as forming, deep drawing, and / or extrusion. The battery cell housing can be made in one piece or in multiple pieces. The battery cell housing can have at least one cover. At least one electrical contact for the electrical connection of the electrode assembly can be arranged on the cover. The first housing wall can form the cover.

[0010] Apart from the pressure relief devices, the first housing wall can primarily, and in particular exclusively, have a first material thickness. This material thickness is the wall thickness, meaning the wall thickness. The first material thickness can range between 0.3 and 2 mm.

[0011] The pressure relief devices prevent uncontrolled rupture of the battery cell casing in the event of thermal runaway. These devices are designed to release excessive internal pressure within the cell's volume through controlled rupture. This controlled rupture of the battery cell casing via the pressure relief devices prevents the pressure from spreading to potentially adjacent battery cells.

[0012] The bursting structure can define the opening cross-section of the first housing wall created by the bursting. The bursting structure can be located on the outside and / or inside of the first housing wall. The bursting structure can be implemented on one or both sides of the first housing wall.

[0013] The burst structure can have a length in one direction and a width in a second direction perpendicular to the first. The length-to-width ratio can be between 4 and 10. The first direction can be parallel or angled to an edge of the first casing wall.

[0014] The second material thickness can be between 0.05 and 0.2 mm. The ratio of the width and / or length of the burst structure to the second material thickness can be greater than 10 and preferably less than 1000.

[0015] Bursting can involve tearing and deformation of the first housing wall in the area of ​​the pressure relief device. Bursting is irreversible.

[0016] The formation of the internal volume can be carried out before, at the same time as, or after the first processing step.

[0017] In a preferred embodiment of the invention, it is advantageous if the first processing method comprises at least one forming step. This processing step may include embossing, broaching, deep drawing, upsetting, rolling, and / or punching. A preferred embodiment of the invention is advantageous in which the first processing method comprises at least one machining step. This can reduce or prevent work hardening in the burst structure region. Work hardening is a process that occurs during the plastic deformation of materials, particularly metals, at temperatures below the recrystallization temperature of the material.In this process, the material is strengthened by forming processes, in particular by disturbing the crystal structures of the material during plastic deformation and creating dislocations (lattice defects) within the crystal lattice, which hinder the movement of further dislocations and thus lead to an increase in strength.

[0018] The machining step can include milling, drilling, etching and / or electrical discharge machining (EDM).

[0019] In an advantageous embodiment of the invention, the bursting structure comprises a bursting groove at least in sections. The bursting groove can extend along a predetermined path and have a constant or variable cross-section along this path. The bursting groove can have a rectangular or triangular cross-section, at least in sections, and in particular primarily.

[0020] The burst groove can have a length in a longitudinal direction, particularly in a main extension direction, between 30 and 70 mm.

[0021] In a preferred embodiment of the invention, it is advantageous if the burst groove has a notch-shaped cross-section, at least in sections. The tip of the notch, viewed in cross-section, can be rounded. The radius of curvature can be between 0.05 and 0.4 mm. The opening angle of the notch towards the surface of the first housing wall can be between 30° and 80°.

[0022] In a preferred embodiment of the invention, the burst groove follows a straight path, at least in sections. This path can comprise a line. The path can be circular, arcuate, rectangular, wavy, oval, and / or straight, at least in sections, and preferably predominantly, entirely. The straight path can be parallel or angled to an edge of the first housing wall.

[0023] In a preferred embodiment of the invention, the overpressure relief means have at least one predetermined breaking point adjoining the bursting structure, with a third material thickness that is smaller than the second material thickness. With regard to the bursting of the battery cell housing, the predetermined breaking point can form the weakest point of the overpressure relief means, from which the cracking associated with the bursting originates. The bursting of the first housing wall, and in particular of the entire battery cell housing, can begin at the predetermined breaking point.

[0024] The predetermined breaking point can be created using a second machining process. This second machining process can be different from or identical to the first. The second machining process can include a machining and / or forming step.

[0025] A preferred embodiment of the invention is advantageous in which the overpressure relief means have at least one burst limit, spatially offset from the predetermined breaking point, with a fourth material thickness smaller than the first. The burst limit can spatially confine the bursting of the first housing wall along the burst structure. The burst limit can act as a crack limiter during bursting. The burst limit prevents the bursting from spreading to the areas of the first housing wall surrounding the overpressure relief means.

[0026] The burst limiter can follow a predetermined path along the first housing wall. This path can be circular, arc-shaped, rectangular, wavy, oval, and / or straight, at least in sections, and preferably primarily, or even entirely.

[0027] The burst limiter can be located at the end of the bursting structure, in particular the burst groove. The burst limiter can form a transition between the burst groove and the connection area of ​​the first housing wall with the first material thickness, adjacent to the overpressure relief means.

[0028] The burst limiter can also enclose the burst groove, at least partially, and in particular completely. The burst limiter can be spatially separated from the burst groove and / or the predetermined breaking point.

[0029] The fourth material thickness can be smaller than, the same as, or larger than the second and / or third material thickness.

[0030] The burst limit can be achieved using a third machining process. This third machining process may be different from or identical to the first and / or second machining processes. The third machining process may include a machining and / or forming step. Furthermore, within the scope of the invention, a battery cell housing with the features of claim 9 is proposed to solve at least one of the aforementioned problems.

[0031] Furthermore, within the scope of the invention, a battery cell with the features of claim 10 is proposed to solve at least one of the aforementioned problems. The battery cell can be arranged in a mobile device, for example a vehicle, or a stationary unit.

[0032] Further advantages and advantageous embodiments of the invention will become apparent from the description of the figures and the illustrations.

[0033] Character description

[0034] The invention is described in detail below with reference to the illustrations. These show, in detail:

[0035] Figure 1: A spatial view of a battery cell housing in a special

[0036] embodiment of the invention.

[0037] Figure 2: A cross-section of a burst groove of a battery cell housing in a further special embodiment of the invention.

[0038] Figure 3: A process step of a process for manufacturing a

[0039] Battery cell housing in a special embodiment of the invention.

[0040] Figure 4: A spatial view of overpressure relief medium of a

[0041] Battery cell housing in a further special embodiment of the invention.

[0042] Figure 5: A method for manufacturing a battery cell housing in a further special embodiment of the invention.

[0043] Figure 6: A cross-section of a first housing wall of a

[0044] Battery cell housing in a further special embodiment of the invention.

[0045] Figure 7: A cross-section of overpressure relief means of a battery cell housing in a further specific embodiment of the invention. Figure 8: A three-dimensional view of overpressure relief means of a

[0046] Battery cell housing in a further special embodiment of the invention.

[0047] Figure 9: A cross-section of overpressure relief medium of a battery cell housing in a further special embodiment of the invention.

[0048] Figures 10 and 11: A top view of overpressure relief means of a battery cell housing, each in a further special embodiment of the invention.

[0049] Figure 12: A spatial view of overpressure relief medium of a

[0050] Battery cell housing in each of a further special embodiment of the invention.

[0051] Figure 13: A spatial view of overpressure relief medium of a

[0052] Battery cell housing in each of a further special embodiment of the invention.

[0053] Figure 14: A bursting process with respect to a cross-section along AA of the

[0054] Overpressure relief device from Figure 13.

[0055] Figure 1 shows a spatial view of a battery cell housing in a special embodiment of the invention. The battery cell housing 10 for a battery cell 12 has a prismatic shape and comprises several housing walls 16 that are integrally connected and at least partially define an internal volume 14, and below which is a first housing wall 18 to which at least two further housing walls 16 are connected.

[0056] Within the internal volume 14, an electrode arrangement (not shown here) for generating electrical energy for the battery cell 12 can be arranged.

[0057] In the first housing wall 18, pressure relief devices 20 are arranged to reduce overpressure in the internal volume 14 and prevent uncontrolled bursting of the battery cell housing 10. The pressure relief devices 20 are formed as a single unit from the first housing wall 18 and include a bursting structure 22 in the first housing wall 18.

[0058] The bursting structure 22 comprises a bursting groove 24 that follows a completely straight path 26. The bursting groove 24 preferably has a length 28 of 50 mm in a longitudinal direction 30. Figure 2 shows a cross-section of a bursting groove of a battery cell housing in a further specific embodiment of the invention. The first housing wall 18 can have a first material thickness D1, for example 0.5 mm. The bursting structure 22, here the bursting groove 24, has a second material thickness D2, for example 0.15 mm, which is smaller than the first material thickness D1.

[0059] The burst groove 24 has a notch-shaped cross-section, at least in sections, and the tip 32 of the notch 34 is rounded in cross-section. A radius of curvature R of 0.4 mm may be present. The opening angle 36 of the notch 34 may be 55°.

[0060] Figure 3 shows a process step of a method for manufacturing a battery cell housing in a specific embodiment of the invention. The method 38 comprises the process step of introducing the overpressure relief agents 20 in one piece into the first housing wall 18, which has the first material thickness D1. A first machining process 42 is carried out, by which the burst structure 22, here the burst groove 24, is formed in the first housing wall 18. The first machining process 42 includes a machining step 44, by which the material thickness of the burst structure 22 is reduced to a second material thickness D2, which is smaller than the first material thickness D1.

[0061] The tool 46 used in the machining step 44 can, for example, be a milling head, and the machining step can include milling.

[0062] Figure 4 shows a three-dimensional view of the overpressure relief means of a battery cell housing in a further specific embodiment of the invention. The overpressure relief means 20 have a first groove extension 48 adjoining the burst groove 24 at its end and a second groove extension 50 opposite the first groove extension 48 with respect to the burst groove 24, each of which can act as a shear point. With respect to the bursting of the battery cell housing, the first and second groove extensions 48, 50 can form the weakest point of the overpressure relief means 20, from which the cracking associated with the bursting originates.

[0063] Figure 5 shows a method for manufacturing a battery cell housing in a further specific embodiment of the invention. First, a groove extension 52, which can, for example, be a predetermined breaking point, is formed in the first housing wall 18 by a second machining process 54, which includes, in particular, a machining step involving drilling. Alternatively, the groove extension 52 can be produced by forming. The groove extension 52 has a third material thickness D3 that is smaller than the second material thickness D2.

[0064] The burst groove 24 is then formed in the first housing wall 18 by the first machining process 42 with a machining step 44, for example by milling. Due to the smaller third material thickness D3, any burr that may be present at the transition between the groove extension 52 and the burst groove 24 can be removed by the first machining process 42.

[0065] Figure 6 shows a cross-section of a first housing wall of a battery cell housing in a further specific embodiment of the invention. The pressure relief means 20 have the first groove extension 48, which adjoins the burst groove 24 at its end. Furthermore, the pressure relief means 20 have a burst limit 56 spatially offset from the first groove extension 48, with a fourth material thickness D4 that is smaller than the first material thickness D1. The fourth material thickness D4 is preferably larger than the second material thickness D2. The burst limit 56 restricts the opening area of ​​the pressure relief means 20 during a bursting event in which the burst structure 22 ruptures.

[0066] Figure 7 shows a cross-section of the overpressure relief element of a battery cell casing in a further specific embodiment of the invention. The bursting structure 22 has end-enlarged burst grooves 58 that extend at an angle on both sides from the straight section 26 of the burst groove 24. The enlarged burst grooves 58 can create a larger opening cross-section of the overpressure relief element 20 during the bursting process.

[0067] Figure 8 shows a spatial view of overpressure relief means of a battery cell housing in a further special embodiment of the invention. The overpressure relief means 20 comprise two joined burst grooves 24 following an arc-shaped path 26, which have groove extensions 52 at the two opposite intersection points 60.

[0068] Figure 9 shows a cross-section of overpressure relief means of a battery cell housing in a further special embodiment of the invention. The overpressure relief means 20 are similar to those in Figure 8, however, these are surrounded by a burst limit 56, which is spaced apart from the burst groove 24 and the groove extension 52, which can act as a predetermined breaking point.

[0069] Figures 10 and 11 show a top view of overpressure relief means of a battery cell housing, each in a further specific embodiment of the invention. In Figure 10, overpressure relief means 20 are shown, which are identical to those in Figure 8; however, on one side of the burst groove 24, opposite the groove extension 52, two round burst stops 56 are provided, spaced apart from each other. Due to a spacer 62 between the burst stops 56, in the event of a burst, the ruptured housing part 64 of the first housing wall 18 can remain attached to the first housing wall 18, thus preventing it from detaching.

[0070] The first partial length L1 can be between 15 and 35 mm. The second partial length L2 can be between 35 and 15 mm. The width b of the spacing range 62 can be between 1 and 5 mm. The height a can be between 2 and 6 mm. A radius of curvature R can be specified depending on the height a and the first partial length L1 and can, for example, be 80 mm.

[0071] The overpressure relief means 20 in Figure 11 are the same as those in Figure 10, except for an additional surrounding burst limit 56.

[0072] Figure 12 shows a spatial view of overpressure relief means of a battery cell housing in each of a further specific embodiment of the invention. The overpressure relief means 20 are similar to those in Figure 4; however, the burst groove 24 follows an arc-shaped path 26.

[0073] Figure 13 shows a three-dimensional view of overpressure relief means of a battery cell housing in each of a further specific embodiment of the invention. The overpressure relief means 20 are similar to those in Figure 12; however, a burst limit 56, which follows a linear path 26, is connected adjacent to the burst groove 24. At the intersection points 60 between the burst groove 24 and the burst limit 56, groove extensions 52 are provided opposite each other.

[0074] Figure 14 shows a bursting process with respect to a cross-section along AA of the overpressure relief means from Figure 13. In Figure 14 a), the overpressure relief means 20 are shown before a bursting process, and in Figure 14 b), during the bursting process. The burst limit 56 acts as a hinge during a tear 66 along the burst contour of the burst groove 24, around which the torn wall section 68 bends. The fourth material thickness D4 is greater than the second material thickness D2 for this purpose. Reference numeral list

[0075] 10 battery cell housings

[0076] 12 battery cells

[0077] 14 internal volume

[0078] 16 case walls

[0079] 18 first case wall

[0080] 20 Overpressure relief agents

[0081] 22 Burst structure

[0082] 24 Burstnut

[0083] 26 Route description

[0084] 28 Length

[0085] 30 Longitudinal direction

[0086] 32 peak

[0087] 34 notch

[0088] 36 opening angles

[0089] 38 procedures

[0090] 40 Bring in

[0091] 42 first processing procedure

[0092] 44 machining step

[0093] 46 tools

[0094] 48 first groove extension

[0095] 50 second groove extension

[0096] 52 Groove extension

[0097] 54 second processing procedure

[0098] 56 Burst limit

[0099] 58 extended bursting nut

[0100] 60 Intersection

[0101] 62 Distance range

[0102] 64 Housing part 66 Tearing

[0103] 68 cracked wall section

[0104] D1 first material thickness

[0105] D2 second material thickness

[0106] D3 third material thickness

[0107] D4 fourth material thickness

[0108] L1 first partial length

[0109] L2 second part length

[0110] R radius of curvature a height b width

Claims

Patent claims 1. Method (38) for manufacturing a battery cell housing (10) for a battery cell (12), comprising the steps Formation of an internal volume (14) at least partially delimited by several housing walls (16) connected to each other in one piece and Introducing (40) an overpressure relief agent (20) to reduce overpressure in the internal volume (14) to prevent uncontrolled bursting of the battery cell housing (10) in one piece into at least one first housing wall (18) of the housing walls (16) having a first material thickness (D1) with at least one first processing method (42) forming a bursting structure (22) in the first housing wall (18), which reduces the material thickness at least section by section to a second material thickness (D2) that is smaller than the first material thickness (D1) in the bursting structure (22).

2. Method (38) for manufacturing according to claim 1, characterized in that the first processing method (42) comprises at least one forming processing step.

3. Method (38) for manufacturing according to claim 1 or 2, characterized in that the first machining method (42) comprises at least one machining step (44).

4. Method (38) for production according to one of the preceding claims, characterized in that the bursting structure (22) comprises at least sectionally a bursting groove (24).

5. Method (38) for manufacturing according to claim 4, characterized in that the burst groove (24) has a notch-shaped cross-section at least in sections.

6. Method (38) for manufacturing according to claim 4 or 5, characterized in that the burst groove (24) follows a straight path (26) at least section by section.

7. Method (38) for production according to one of the preceding claims, characterized in that the overpressure relief means (20) have at least one that adapts to the The burst structure (22) has a subsequent predetermined breaking point (52) with a third material thickness (D3) that is smaller than the second material thickness (D2).

8. Method (38) for production according to claim 7, characterized in that the overpressure relief means (20) have at least one burst limit (56) spatially offset from the predetermined breaking point (48, 50, 52) with a fourth material thickness (D4) that is smaller than the first material thickness (D1).

9. Battery cell housing (10) for a battery cell (12) which is manufactured by a method (38) according to one of the preceding claims.

10. Battery cell (12) with a battery cell housing (10) according to claim 9 and at least one electrode arrangement contained in the internal volume (14) and providing electrical energy.

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