Method for shortening seal portions

Abstract

The invention relates to a method for creating or processing a seal region of a cell housing of a battery cell, wherein the seal region is formed from at least two layers of material which are positioned one above the other and at least in certain regions delimit a receiving space of the cell housing, wherein the seal region and / or the cell housing is fixed, and wherein at least a second portion of the seal region is plastically deformed by a bending tool in order to shorten a length of the second portion. The invention also relates to a battery cell.

Description

[0001] METHOD FOR SHORTENING SEAL SECTIONS

[0002] The invention relates to a method for machining a sealing region of a cell housing of a battery cell, wherein the sealing region is formed from at least two interconnected material layers that at least partially delimit a receiving space of the cell housing. Furthermore, the invention relates to a battery cell with at least one machined sealing region.

[0003] In addition to so-called hard-case cells, pouch cells with flexible or foil-like cell housings are also known. Such cell housings can be made from multiple material layers, typically including an aluminum layer. The cell housing is pocket-shaped and has a receiving space for cell components, which, depending on the design of the cell housing, is defined and sealed by, for example, three or four sealing sections.

[0004] In electrochemical storage devices, such as lithium-ion batteries, the cell components arranged in the receiving space are formed from electrode packs. Such electrode packs consist of alternating layers of anodes, cathodes, and separators.

[0005] The anode foils and cathode foils can be formed by winding or stacking and positioned in the interior volume or receiving space of the cell casing for final use. During battery cell production, the respective anode foils and cathode foils are connected to the battery terminals, which are led out of the receiving space through contact feedthroughs. Pouch cell casings are typically manufactured using a bookfolding process, in which a preformed arrangement of material layers is folded along a fold line to form the receiving space. The material layers are then bonded to the sides of the receiving space using pressure and heat to form sealing sections that define the receiving space.This creates so-called bat-ears, particularly at the intersection point between the fold line and a sealing section, which impair the dimensional stability of the battery cell due to excess material from the sealing section.

[0006] Such bat-ears protrude from the bottom, for example, and can prevent or at least make it difficult for the bottom surface of the cell housing to rest flatly on a module frame or on a cooling plate, for example.

[0007] For example, EP 4 123 792 A1 discloses a method that proposes lateral folding or rolling of the resulting bat-ears to facilitate the positioning of the battery cells in a module housing. The folded bat-ears remain below the battery cell at the bottom, forming a gap between the battery cell and the module housing.

[0008] EP 4 024 548 A1 describes a method for producing pouch battery cells, in which a folded edge of the electrode stack's casing is pre-formed into an M-shape or W-shape. As a result, the finished battery cell has a bottom fold that has a larger volume than conventional battery cells.

[0009] The present invention therefore aims to provide a method for processing a sealing region of a cell housing, which can prevent the formation of bat-ears or correct bat-ears that have already formed. This object is achieved by the features specified in claim 1. Further advantageous embodiments of the invention are part of the subclaims. According to one aspect of the invention, a method for creating or processing a sealing region of a cell housing of a battery cell is provided. The sealing region has at least two material layers arranged one above the other.

[0010] The material layers can be parts of two half-shells or foils that can be connected to each other in the sealing area. Each of these material layers or foils can consist of several layers, which can, for example, comprise at least one plastic and one aluminum alloy.

[0011] The sealing region can, for example, be formed from edge-side ends of the material layers, which at least partially delimit a receiving space of the cell housing. In a battery cell designed as a pouch cell, the receiving space is formed in the form of a pocket. In one step, the at least one sealing region is fixed to at least a first section by at least one fixing. Subsequently, at least a second section of the sealing region is plastically deformed by a bending tool in order to shorten a length of the second section. According to the invention, a deformation pattern is impressed into the at least one second section by the bending tool, which deformation pattern has an amplitude in the direction of a surface normal of the second section.

[0012] According to a further aspect of the invention, a battery cell is provided. The battery cell comprises a cell housing with at least one receiving space in which cell components are arranged.

[0013] The battery cell can be designed as a so-called pouch cell, in which the receiving space is designed as a receiving pocket. The receiving space can be formed by pre-bent or tub-shaped half-shells, which are folded together or folded along a fold line.

[0014] The cell components are electrically connected by at least one battery terminal, which leads out of the receiving space through at least one contact feedthrough. The contact feedthrough is provided in at least one sealing area of ​​the cell housing.

[0015] The at least one sealing region is designed to be shortened in length, at least in some regions, by at least one deformation directed in the direction of a surface normal of the sealing region, in particular in the form of a deformation pattern, such as a wave pattern or zigzag pattern.

[0016] The at least one first section and the at least one second section of the at least one sealing region may overlap or intersect or be spaced apart from one another.

[0017] The cell housing may preferably have a plurality of sealing areas or a circumferential sealing area, which may be I-shaped, L-shaped or U-shaped, for example.

[0018] The plastic deformation of the material layers in the second section of the sealing area is advantageously directed transversely to a longitudinal extension of the sealing area and causes a deflection or local bending of the material layers, which reduces the effective length of the second section. This measure can reduce or eliminate material overhang or so-called bat-ears, particularly at the end of the sealing area.

[0019] The bending tool can be designed as a separate tool or as a combined bending and joining tool, which, in addition to plastically deforming the material layers, also enables thermal bonding of the material layers. In one embodiment, the bending tool can also be designed as a partial area or as a section of a joining tool for forming at least one sealing area.

[0020] The introduction of plastic deformation of the material layers in the second section of the sealing area can be achieved through the application of heat and / or pressure. In addition to a mechanical punching movement, plastic deformation can also be achieved through local temperature effects with subsequent material distortion.

[0021] In one embodiment, the at least one second section of the sealing region is plastically deformed parallel to a surface normal. This allows the effective length or extension of the material layers along the second section to be reduced particularly easily from a technical perspective.

[0022] Material overhangs formed by producing sealing areas or a sealing area can be removed in a subsequent process if at least two interconnected material layers in at least the second section of the sealing area are plastically deformed by the bending tool in order to shorten the length of the second section.

[0023] According to an alternative embodiment of the method, the material layers are joined together by the bending tool at least in the second section of the sealing area and plastically deformed to shorten the length of the second section. This measure enables the simultaneous formation of sealing areas with at least local corrections of bat ears.

[0024] According to a further embodiment, the sealing region has at least one contact feedthrough. At least one first section is arranged on one side or both sides of the contact feedthrough. Advantageously, the sealing region is secured to one of the two first sections or to both first sections by at least one fixing. This allows the cell housing and / or the battery cell to be secured particularly reliably in order to be able to introduce plastic deformation precisely into the second section of the sealing region. In the region of the contact feedthrough, the sealing region can be structurally reinforced and rigid in order to pass through battery terminals. Alternatively, the sealing region at contact feedthroughs can be designed to be particularly rigid and torsionally resistant due to the presence of battery terminals.

[0025] The second section can be shortened particularly efficiently in its elongated extent if the bending tool imprints a deformation pattern in the form of a wave pattern into the at least one second section, which has an amplitude in the direction of a surface normal of the second section.

[0026] According to a further embodiment, the shortening of the second section is adjusted by a wavelength and / or by the amplitude of the wave pattern. This allows different parameters of the wave pattern to be used to variably adjust the degree of shortening of the second section due to plastic deformation.

[0027] Already formed bat-ears or the formation of bat-ears along the sealing section can be technically easily avoided or eliminated if the bending tool imprints a zigzag pattern with several straight and / or curved segments into the at least one second section, which is deflected in the direction of a surface normal of the second section.

[0028] According to a further embodiment, the zigzag pattern is embossed into the at least one second section by the bending tool with segments of equal or different lengths. The respective segments of the zigzag pattern are angled relative to one another and can thus have different or equal lengths. This measure enables particularly precise adjustment of the shortening of the second section of the sealing area or adjustment of a final length of the sealing area. The available space in the direction of the surface normal of the second section can be optimally utilized if the length of the segments can be adapted to the available space.

[0029] The shortening of the second section of the sealing area can be adjusted technically easily if a relative angle of the segments of the zigzag pattern with respect to a course of the second section before deformation by the bending tool is used to adjust the shortening of the second section.

[0030] Depending on the design, the embossed wave or zigzag pattern can have any length. For example, the respective patterns can have an S-shape, a double S-shape, a triple S-shape, and the like, whereby an S-shape can be configured as a wavelength of the corresponding pattern.

[0031] According to a further embodiment, the bending tool is used to deform at least one second section of the sealing area arranged on the head side and / or the bottom side. This allows for locally correcting sealing areas or bat ears that protrude at the edges to ensure the dimensional accuracy of the battery cell.

[0032] The correction of bat-ears can be flexibly implemented in a manufacturing process of battery cells if the plastic deformation of the at least one second section is carried out before closing the receiving space or after closing the receiving space.

[0033] Several embodiments of the invention are explained in more detail below with reference to the drawings. They show:

[0034] Fig. 1 is a schematic representation of a battery cell before removing bat-ears according to an embodiment of the invention, Fig. 2 shows detailed representations of the battery cell from Fig. 1 after a method has been carried out according to an embodiment of the invention,

[0035] Fig. 3 schematic representations to illustrate a shortening of a second section of a sealing area due to a plastic deformation,

[0036] Fig. 4 is a perspective view illustrating a shortening of a second section of a sealing region due to plastic deformation by a method according to a further embodiment of the invention, and

[0037] Fig. 5 is a plan view of a sealing area to illustrate a method according to another embodiment of the invention.

[0038] In the illustrations, identical reference numerals identify the same elements or structural components. The sizes and relative positions of the elements in the illustrations are not necessarily drawn to scale, and some of these elements are enlarged and positioned for clarity. Furthermore, the specific shapes of the elements shown are not intended to convey information about the actual shape of the individual elements, but were selected merely for ease of identification in the illustrations.

[0039] The figures illustrate a method for creating or processing a sealing region 20 of a cell housing 110 of a battery cell 100.

[0040] Fig. 1 shows a schematic representation of the battery cell 100 prior to the removal of so-called bat-ears 200 according to one embodiment of the invention. The bat-ears 200 are bulges 200 in the edge regions or corner regions between fold lines F of the cell housing 110 and the sealing region 20 adjacent to this fold line F, in which material layers of the cell housing 110 are joined together. Such bat-ears 200 are formed particularly in battery cells 100 in the form of pouch cells and, in the illustrated embodiment, protrude on the bottom side beyond a desired geometry or desired edge of a bottom 111 of the cell housing 110. As a result, the bottom 111 of the cell housing cannot lie flat on a support or housing, which can result in thermal and / or mechanical impairments of the battery cell 100.

[0041] The battery cell 100 has, for example, a cell housing 110 with a receiving space 120 in which cell components (not shown) are arranged.

[0042] The cell components arranged in the receiving space 120 consist, for example, of alternating layers of anodes, cathodes, and separators. The anodes and cathodes are designed, for example, as foils and can be formed by winding or stacking and positioned in the receiving space 120 of the cell housing 110.

[0043] During battery cell production, the respective anode foils and cathode foils are connected to battery poles 101, 102, which are led out of the receiving space 120 through contact feedthroughs 23.

[0044] The contact feedthroughs 23 are arranged on opposite sides of the cell housing 110 and enable the battery poles 101, 102 to be led out through the sealing sections 20.

[0045] At the sealing sections 20, the material layers forming the receiving space 120 can be glued and / or welded together in order to limit and / or define the receiving space 120 in certain areas.

[0046] The receiving space 120 can be formed by pre-bent or trough-shaped half-shells (not shown), which are folded together or folded along the fold line F. In the illustrated embodiment, the fold line F runs along the bottom 111 of the cell housing 110 below the receiving space 120. Due to the connection of the material layers along the sealing region 20, bulges or bat-ears 200 are formed on the bottom side, which protrude beyond a desired geometry of the bottom 111. In the detailed view A, this deviation is illustrated by the arrows. To correct this bulge or the bat-ears 200, the method according to the invention is used, in which, for example, a wave pattern or zigzag pattern is introduced into the sealing region 20 in order to shorten the bulge 200.

[0047] Fig. 2 shows detailed representations of the battery cell 100 from Fig. 1 after a method according to an embodiment of the invention was carried out, in which a plastic deformation of the sealing region 20 was carried out by a bending tool (not shown) in order to correct the formed bat-ears 200. Fig. 2A shows a perspective representation of detail view A from Fig. 1, and Fig. 2B shows a side view of the plastically deformed second section 22 of the sealing region 20 of detail view A from Fig. 1.

[0048] Furthermore, the direction of the shortening or correction of the bulge 200 is visualized by the arrow in Fig. 2A. In the illustrated embodiment, the embossed deformation pattern pulls the bulge upward or toward the contact feedthrough 23.

[0049] The figures also illustrate that the battery poles 101, 102 are insulated from material layers 11, 12 of the cell housing 110 by an additional insulation layer 13.

[0050] In the illustrated embodiment, a bending tool was applied to a second section 22 of the sealing region 20, and permanent deformation was achieved by applying pressure and temperature to the material layers 11, 12 in the second section 22 of the sealing region 20 using the bending tool. In the illustrated embodiment, the deformation is implemented in the form of a zigzag pattern or a jagged S-shape. For example, a zigzag pattern with three segments 31, 32 was created, of which two first segments 31 have the same length and a second segment 32 has a length that corresponds to twice the length of a first segment 21.This relationship is particularly advantageous since it creates a wavelength, so to speak, in order to shorten a previous actual length of the second section 22 to a desired length and to correct or at least reduce a bulge 200 of the sealing area 20 beyond the base 111.

[0051] In Fig. 3A, a comparison of an actual length LIST of the second section 22 with the bulge 200 or the bat-ears is schematically illustrated with a corrected length of the second section 22 of the sealing area 20, which due to the correction by the plastic deformation of a target length L SO LL. Fig. 3A also illustrates the plastic deformation of the second portion 22 of the sealing region 20 parallel to or at least in the direction of surface normal N.

[0052] For example, the target length L SOLL corresponds to 14 mm and the actual length LIST of the second section 22 is 15 mm. The introduced plastic deformation results in a shortening of 1 mm and the restoration of the dimensional accuracy of the battery cell 100.

[0053] The shortening of the second section 22 of the sealing region 20 can be further adjusted by using a relative angle a of the segments 31, 32 of the zigzag pattern relative to a profile 30 of the second section 22 prior to deformation by the bending tool. For example, the relative angle a can be increased to shorten the second section 22 of the sealing region 20. In the illustrated embodiment, the relative angle a corresponds to approximately 25°.

[0054] Depending on the design, a bending tool can be used multiple times. After each application, with a corresponding plastic deformation of the material layers 11, 12 in the second section 22, parameters such as the relative angle α can be changed to progressively adjust the bulge 200. With such a step-by-step approach, elastic restoring moments of the imposed deformation pattern due to the plastic deformation in the second section 22 can also be taken into account.

[0055] Before applying the bending tool, the cell housing 110 can be secured or locked by a fixation (not shown) in the region of a first section 21 of the sealing area 20 to prevent unintentional slipping of the cell housing 110. Depending on the design, the cell housing 110 or the entire battery cell 100 can be secured alternatively or additionally by inserting it into a half-shell or a receiving recess (not shown).

[0056] In the illustrated embodiment, the cell housing 110 is locked in place at a first section 21 of the sealing region 20, which partially overlaps the contact feedthrough 23 or is arranged directly adjacent to the contact feedthrough 23. The battery cell 100 can preferably be locked on both sides or at both battery poles 101, 102 or correspondingly at the first sections 21 arranged adjacent to the battery poles 101, 102.

[0057] Figure 3B illustrates the relative position of the first section 21 and the second section 22 of the sealing region 20. Furthermore, bend lines or bend points 33 of the deformation pattern in the second section 22 are visualized to illustrate the plastic deformation step.

[0058] Fig. 4 shows a further sectional view of plastically deformed material layers 11, 12 in the second section 22 of the sealing region 20. In contrast to the cross-section shown in Fig. 3A, the plastic deformation is carried out as two S-shapes arranged in a row, whereby more bending points 33 and more segments 31, 32 are generated in the second section 22. The relative angle α can, for example, be in a range of 22° - 23°. The resulting deformation pattern consists, for example, of two first segments 31 and three second segments 32, which can essentially be considered as two wavelengths.

[0059] Fig. 5 shows a plan view of a sealing region 20 to illustrate a method according to a further embodiment of the invention. In contrast to the previously described embodiments, here a plastic deformation of the material layers 11, 12 in the second section 22 of the sealing region 20 is implemented such that the respective segments 31, 32 extend across the entire width of the sealing region 20 up to the receiving space 120. As a result, the entire width B of the sealing region 20 can be used to correct bulges 200 or bat ears.

Claims

CLAIMS 1. A method for producing or processing a sealing region (20) of a cell housing (110) of a battery cell (100), wherein the sealing region (20) is formed from at least two material layers (11, 12) arranged one above the other, which at least partially delimit a receiving space (120) of the cell housing (110), wherein the sealing region (20) and / or the cell housing (110) is fixed, characterized in that at least a second section (22) of the sealing region (20) is plastically deformed by a bending tool in order to shorten a length (LIST) of the second section (22), wherein the bending tool impresses a deformation pattern into the at least one second section (22) which has an amplitude in the direction of a surface normal (N) of the second section (22).

2. The method according to claim 1, wherein the at least one second section (22) of the sealing region (20) is plastically deformed parallel to and / or in the direction of at least one surface normal (N) of the second section (22).

3. The method according to claim 1 or 2, wherein the material layers (11, 12) are connected to one another and plastically deformed by the bending tool at least in the second section (22) of the sealing region (20) in order to shorten a length (LIST) of the second section (22); or wherein at least two material layers (11, 12) connected to one another in at least the second section (22) of the sealing region (20) are plastically deformed by the bending tool in order to shorten the length (LIST) of the second section (22).

4. Method according to one of claims 1 to 3, wherein the sealing region (20) has at least one contact feedthrough (23), wherein at least one first section (21) is arranged on one side or both sides of the contact feedthrough (23), and wherein the sealing region (20) is fixed to one of the two first sections (21) or to both first sections (21) by at least one fixing.

5. Method according to one of claims 1 to 4, wherein a deformation pattern in the form of a wave pattern is impressed into the at least one second section (22) by the bending tool, which deformation pattern has an amplitude in the direction of a surface normal (N) of the second section (22).

6. The method according to claim 5, wherein the shortening of the second section (22) is adjusted by a wavelength and / or by the amplitude of the wave pattern.

7. Method according to one of claims 1 to 6, wherein a deformation pattern in the form of a zigzag with a plurality of straight and / or curved segments (31, 32) is impressed by the bending tool into the at least one second section (22) of the sealing region (20), which deformation pattern is deflected in the direction of at least one surface normal (N) of the second section (22).

8. according to claim 7, wherein the zigzag pattern with equally long or differently long segments (31, 32) is embossed into the at least one second section (22) by the bending tool.

9. The method according to claim 7 or 8, wherein a relative angle (a) of the segments (31, 32) of the deformation pattern designed as a zigzag pattern with respect to a course (30) of the second section (22) before the deformation tion by the bending tool is used to adjust the shortening of the second section (22).

10. Method according to one of the preceding claims, wherein the bending tool is used to deform at least one second section (22) of the sealing region (20) arranged on the head side and / or bottom side.

11. Method according to one of the preceding claims, wherein the plastic deformation of the at least one second section (22) is carried out before closing the receiving space (120) or after closing the receiving space (120).

12. Battery cell (100), comprising a cell housing (110) with at least one receiving space (120) in which cell components are arranged, wherein the cell components are electrically connected by at least one battery pole (101, 102) which is led out of the receiving space (120) through at least one contact feedthrough (23), wherein the contact feedthrough (23) is provided in at least one sealing region (20) of the cell housing (110), and wherein the at least one sealing region (20) is designed to be shortened in length at least in regions by at least one deformation directed in the direction of a surface normal (N) of the sealing region (20).

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