Method for manufacturing a battery cell, forming device and battery cell

Abstract

Method for manufacturing a battery cell (1), comprising at least a housing (2) and at least one stack (3) of electrode foils (4) arranged therein, wherein the housing (2) is made of a foil material (5) by folding the foil material (5); wherein the method comprises at least the following steps: a) providing a die (6) of at least two parts, with at least one first recess (7) in a first die part (8) and a second recess (9) spaced apart from the first recess (7) in a second die part (10), which is hinged relative to the first die part (8); b) arranging at least one foil material (5) on the die (6) in a starting position (11) and over the recesses (7, 9) in a surface section (12);c) first forming of the film material (5) along an imaginary fold line (13) with a preforming die (14) or a preforming device in an area (15), wherein the fold line (13) runs between the recesses (7, 9); wherein the formed area (15) of the film material (5) forms a material reservoir for the subsequent second forming of the film material (5); d) second forming of the film material (5) in the area of ​​the recesses (7, 9) with a punch tool (16) having punch geometries corresponding to the recesses (7, 9), wherein during the second forming the film material (5) present in the material reservoir is displaced towards the recesses (7, 9); e) arranging the at least one stack (3) in the film material (5) and closing the film material (5) in an edge area (17) to form the housing (2) and to complete the battery cell (1).;

Description

[0001] The invention relates to a battery cell as well as a method and a device for manufacturing a battery cell.

[0002] The battery cell comprises a gas-tight housing and, arranged within it, at least one stack of electrode foils stacked on top of each other. The housing is made of a foil material by folding the foil material.

[0003] A battery cell is an energy storage device used, for example, in a motor vehicle to store electrical energy. In particular, a motor vehicle has an electric motor to propel it, which can be driven by the electrical energy stored in the battery cell. In a battery cell, electrode foils, i.e., anodes and cathodes, are stacked on top of each other, with different electrode foils separated from each other by separator foils or a separator material. The electrode foils are immersed in an electrolyte. Battery cells with liquid or solid electrolytes (solid-state batteries) are known, for example.

[0004] A battery module comprises, in particular, a plurality of battery cells that are electrically connected in series or parallel and arranged in a module housing. Individual battery modules can also be electrically connected in series or parallel. A battery comprises one or more battery modules.

[0005] Battery cells can be designed as so-called pouch cells (or pocket cells). Pouch cells comprise a composite material, referred to as pouch film, as the casing material. This composite material is a composite material, in particular comprising aluminum and plastic. The casing can be formed by several layers of film material arranged one on top of the other, forming a casing section enclosing the stack and an edge region projecting radially outwards from the casing section. Alternatively, the casing can be formed by a single film material, with the casing being created by folding the film material. In this case, at least one side of the cell casing does not require a sealing seam to seal the edge region. In the (remaining) edge regions, the overlapping film materials are gas-tightly connected to one another, in particular by a sealing seam.

[0006] There may be a requirement to connect a battery cell to a cooling element or surface for cooling purposes. Cooling cannot be achieved via the side surfaces of the cell casing where the leads exit the casing. With pouch cells, the long, narrow side surfaces are typically connected to cooling surfaces. This connection is usually only made via the side surface where the foil material was folded. The other side surface has a sealing seam. Heat conduction to the cooling surface is impaired on this side surface due to the sealing seam.

[0007] In housings formed from a foil material by folding the foil, cracks frequently occur in the fold area during cell respiration in battery cell operation. Furthermore, the thermoforming capability of the foil material is impaired, at least in areas adjacent to the fold line.

[0008] From WO 2012 / 022448 A1, an electrochemical cell is known whose casing / housing is made from a single casing part, which is folded and sealed. This eliminates the need for a sealing seam on one narrow side of the cell.

[0009] From EP 3 611 775 A1 a battery cell with a casing folded from a flat blank is known.

[0010] From DE 10 2018 104 554 A1, a battery cell is known whose cell casing consists of a film material that is folded along a fold line. At the ends of the fold line, a folding aid, designed as a depression or material addition, is provided laterally adjacent to the fold line to counteract any protrusion of the film material caused by the folding.

[0011] The object of the present invention is to at least partially solve the problems cited with reference to the prior art. In particular, a method for manufacturing a battery cell is proposed in which the battery cell housing is produced from a single film material. The thermoforming properties of the film material are to be improved, thereby preventing the formation of cracks during operation of the battery cell.

[0012] A method with the features according to claim 1 contributes to solving these problems. Advantageous further developments are the subject of the dependent claims. The features listed individually in the claims can be combined in a technologically meaningful way and can be supplemented by explanatory facts from the description and / or details from the figures, thereby showing further embodiments of the invention.

[0013] A method for manufacturing a battery cell is proposed. The battery cell comprises at least one housing and at least one stack of electrode foils arranged therein. The housing is made of a foil material by folding the foil material. The method comprises at least the following steps: a) Providing a die consisting of at least two parts, with at least one first recess in a first die part and a second recess spaced apart from the first recess in a second die part, which is designed to be hinged relative to the first die part; b) (Providing at least one film material and) arranging at least one film material on the matrix in a starting position and over the cutouts in a surface section; c) first forming of the film material along an imaginary fold line with a preforming die or preforming device in an area, wherein the fold line runs between the recesses; wherein the formed area of ​​the film material forms a material reservoir for the subsequent second forming of the film material; d) (providing a punch tool with punch geometries corresponding to the recesses and) second forming of the film material in the area of ​​the recesses with a punch tool with punch geometries corresponding to the recesses, wherein during the second forming the film material present in the material reservoir is moved towards the recesses; e) Arranging the at least one stack in the foil material and sealing the foil material in an edge area to form the housing and to complete the battery cell.

[0014] The above (non-exhaustive) classification of the procedural steps into a) to e) is primarily intended for differentiation purposes and does not impose any sequence or dependency. The frequency of the procedural steps can also vary. It is also possible that procedural steps may overlap, at least partially. In particular, steps a) to e) are carried out in the order listed.

[0015] In a battery cell, electrode foils, i.e., anodes and cathodes, are stacked on top of each other, with different electrode foils separated from one another by separator foils or a separator material. The electrode foils are immersed in an electrolyte. Battery cells with liquid or solid electrolytes (solid-state batteries) are known, for example. The battery cell is, in particular, a lithium-ion battery cell. The electrical contact of the battery cell is effected, in particular, by means of conductors that make electrically conductive contact with the electrode foils inside the battery cell and extend outwards via the housing, in particular via the edge regions formed by the folded foil materials according to step e).

[0016] In particular, the housing is formed solely from a single piece of film material. During the process, the film material is folded along a fold line, which extends only along a straight line. As a result of the folding, the housing has an edge area on one side surface formed by the continuous film material, which requires no further sealing. The edge areas, extending along three sides of a (generally) cuboid housing and formed by the folded film material, are sealed gas-tight, in particular by sealing seams.

[0017] The film material is in particular a pouch film, preferably a composite material, in particular comprising aluminium and plastic.

[0018] According to step a), in particular, a matrix consisting of at least two parts is provided, with at least one first recess in a first matrix part and a second recess spaced apart from the first recess in a second matrix part, which is hinged relative to the first matrix part. The recesses are used to form the housing halves from the film material, which are then folded together to form the housing.

[0019] According to step b), at least one, preferably exactly one, film material is provided and the film material is arranged on the die in a starting position and over the recesses in a surface section. The at least one film material is, in particular, flat. The film material is provided as a continuous material.

[0020] In particular, the foil material extends beyond the surface section at least along an edge of the surface section that runs parallel to the imaginary fold line.

[0021] The die is arranged particularly on one side of the film material.

[0022] According to step c), a first forming of the film material is carried out in particular along an imaginary fold line using a preforming die and / or a preforming device in an area where the fold line runs between the recesses. The formed area of ​​the film material forms a material reservoir for the subsequent second forming of the film material.

[0023] The fold line, which at the present stage of the process is only conceived (planned, predetermined) and only later realized by folding, extends exclusively along a straight line.

[0024] The preforming die is formed, in particular, between the recesses in the die and is movable relative to the die. The preforming die is used to form an area encompassing the fold line. Specifically, the first forming operation is carried out without stretching the film material, i.e., without reducing the thickness of the film material. Specifically, the thickness of the film material in the formed area is reduced by at most 5%, preferably by at most 2%, and most preferably by at most 1% as a result of the first forming operation. Specifically, during the first forming operation, film material from outside the formed area is fed into this area.

[0025] In particular, the first forming process extends the extent of the foil material, which was previously flat, located between the recesses by at least 10%, preferably by at least 20%, and especially preferably by at least 30%.

[0026] In particular, a metal holder is arranged on the opposite side of the film material, i.e., opposite the die, which fixes the film material in a predetermined position on the die. The metal holder also allows the film material to be fed into the surface section during the initial forming process. Specifically, the film material is fed into the surface section from only one direction, e.g., from a material supply device located outside the surface section, such as a roll on which the film material is wound as a continuous piece. This allows other areas of the film material to be fixed by the metal holder and the die.

[0027] The preforming die deforms the foil material, especially towards the sheet metal holder.

[0028] The first forming process can be determined in advance, particularly through simulation, and is controlled via the sheet metal holder and the preforming die.

[0029] The initial forming process can be carried out using air pressure or electromagnetic pulse technology as an alternative to the preforming die.

[0030] In accordance with step d), a die tool with die geometries corresponding to the recesses is provided. The die tool is used to perform a second forming of the film material in the area of ​​the recesses, whereby during this second forming the film material present in the material reservoir is moved towards the recesses.

[0031] The stamping tool is positioned on the same side of the foil material as the sheet metal holder. The foil material is formed by the stamping tool towards the die.

[0032] As a result of the displacement of the film material within the material reservoir, the deep-drawing capability of the film material is significantly improved. Stretching of the film material in the area of ​​the cutouts can thus be reduced. In particular, during the second forming process, the material reservoir is completely dissolved again, so that the stretching of the film material between the cutouts is restored to the state it was in immediately before the first forming process.

[0033] In particular, the film material located between the recesses is stretched at the end of step d), i.e., when the stamping tool has reached its final position in the recesses. Specifically, the stretching reduces the thickness of the film material in the area of ​​the subsequently created fold line by at least 0.5%, preferably by at least 1%.

[0034] In particular, heating elements are arranged along the recesses in the die, which can heat the film material for the second forming process, at least in certain areas. As a result of heating the film material, the deep drawing of the film material in the area of ​​the lateral boundaries of the recesses can be improved, and the risk of the film material cracking can be further reduced.

[0035] According to step e), the at least one stack is arranged in the foil material and the foil material is sealed in one or all edge areas (except the edge area formed by the folding) to form the housing and to complete the battery cell.

[0036] In particular, before step e), the punch tool is removed from the recesses. The sheet metal holder is also removed from the die. During step e), after arranging at least one stack, the film material is folded over the fold line so that the film material is folded on top of each other at the edges, forming a closed volume of the housing. The stack is arranged in the areas of the film material corresponding to the recesses, which are formed as a result of the second forming process. These recess-shaped areas are aligned with each other as a result of the folding, so that the folded film material forms a volume to accommodate at least the stack.

[0037] In particular, the stack is aligned to the recess via the electrode foils' current collectors, thus fixing a specific position of the stack relative to the foil material. This alignment can be achieved using a positioning device, such as rod elements arranged in the die, between which the current collectors are positioned during the stack's placement in the recess.

[0038] In particular, during step c), a quantity of film material used for the material reservoir is at least partially fed into the surface section from outside. Specifically, at least 95% of the film material used for the material reservoir is fed from outside the surface section, preferably at least 99%, and particularly preferably at least 99.9%. This allows the film material to stretch during the second forming process, ensuring sufficient material thickness for deep drawing, even in the areas of the recesses and between the recesses, and preventing the formation of cracks in the housing or the film material during subsequent operation of the battery cell.

[0039] In particular, before step d), and possibly before or during step c), a metal holder is provided which fixes the foil material in the surface section in step x) after step c). Specifically, the foil material is only fixed in those areas of the surface section that do not impede the feeding of the foil material into the surface section.

[0040] In particular, the film material is trimmed between steps x) and d), so that the film material extends only over the area section. The trimming is carried out in particular by a first cutting device, which separates the film material arranged between the die and the punch tool from the film material arranged outside the area section.

[0041] The separation is achieved, for example, by lowering the die and punch tool relative to the first cutting unit. In particular, as a result of this lowering, die inserts are inserted into recesses in the die, ensuring a flat contact surface for the film material within the area and outside the recesses and the surrounding area.

[0042] In particular, during step d), a third forming operation of the film material takes place in the area of ​​the fold line, in which a bending radius is embossed into the film material along the fold line. This third forming operation is performed, in particular, with the preforming die, which further forms the area already formed by the first operation. This third forming operation occurs, in particular, before the second forming operation, i.e., before the forming of the film material in the area of ​​the cutouts. The die tool is used to create the bending radius, and it interacts, in particular, with the preforming die. In particular, the second forming operation occurs simultaneously with the third forming operation.

[0043] In particular, the third forming process only takes place when, as a result of the second forming process, at least 90%, preferably at least 95%, and especially preferably at least 99% of the material reservoir formed by the first forming process has been displaced from the area and towards the recesses. Specifically, the second and third forming processes of the film material are completed simultaneously.

[0044] The bending radius is in particular between 0.5 millimeters and 5 millimeters, preferably at least 1 millimeter, more preferably at least 2 millimeters, more preferably at most 4 millimeters, more preferably at most 3 millimeters.

[0045] The bending radius imprinted by the third forming process defines the fold line, so that the folding of the film material according to step e) takes place automatically along the fold line.

[0046] In particular, a final trimming of the film material takes place during at least the second forming process, thus defining the final geometry of the film material's edge areas. This trimming or cutting is carried out, in particular, by a second cutting device integrated into the die and / or the punch tool. The cutting occurs, in particular, concurrently with the second forming process and preferably immediately after its completion.

[0047] In particular, in step e), after the stack has been arranged in the first recess, the second die part is folded onto the first die part. As a result of this folding motion, the film material is folded along the fold line. The die parts are connected to each other via a (rotary) joint.

[0048] During the folding motion, the film material is fixed in the respective recess, specifically only in the moving recess, via a vacuum connection. The vacuum connection creates a vacuum between the film material and the recess, which holds the film material in place.

[0049] In particular, in step y), the first and second die parts, together with the folded film material and the stack, are pivoted into a sealing position, and the edge area of ​​the film material is sealed in this sealing position. The die inserts are not pivoted, so that these areas of the die, and thus the edge areas of the film material, are now accessible to a sealing tool.

[0050] In particular, after step y), the die parts are swung back into their starting position and the battery cell is removed from the die.

[0051] In particular, the film material is held in the die parts during forming and until sealing according to step y), so that a high degree of dimensional accuracy and reproducibility of dimensional accuracy can be achieved.

[0052] A forming device for manufacturing a battery cell housing is further proposed, wherein the forming device is suitably designed to carry out the described method. The forming device comprises at least • a matrix consisting of at least two parts, with at least one first recess in a first matrix part and a second recess spaced apart from the first recess in a second matrix part, which is designed to be hinged relative to the first matrix part; • a preforming die or preforming device as well as • a stamping tool with stamp geometries corresponding to the recesses.

[0053] The forming device includes in particular a control unit that is equipped, configured or programmed to carry out the described process.

[0054] A further battery cell is proposed, comprising at least a gas-tight housing manufactured by the described method, and containing at least one stack of electrode foils arranged on top of each other. The housing is formed by a foil material that has a fold line along one side surface of the housing.

[0055] The housing is formed in particular by a single film material, wherein the housing is formed by folding the film material.

[0056] The housing does not require a sealing seam on at least one side surface to seal the edge area. In the (remaining) edge areas, the overlapping film materials are gas-tightly joined together, in particular via a sealing seam.

[0057] A further battery cell arrangement is proposed, comprising at least the described battery cell or the battery cell produced by the described method, as well as a cooling surface, wherein the battery cell is arranged on the cooling surface via its edge region (without a sealing seam) or is in thermally conductive contact with it. In particular, the battery cell arrangement comprises a plurality of battery cells.

[0058] The cooling surface is in particular a solid body which is preferably exposed or permeated by a cooling fluid, e.g. a liquid or a gas, on a side facing away from the cooling surface.

[0059] In particular, during operation of the battery cell, heat is dissipated from the battery cell to the surrounding environment via the cooling surface. Of course, temperature control of the battery cell via the cooling surface is also possible, meaning that the battery cell can be heated, at least temporarily, i.e., heat is conducted from the cooling surface to the battery cell.

[0060] In particular, the battery cell arrangement is used in a motor vehicle, especially to provide electrical energy for a traction drive.

[0061] The descriptions of the process are particularly applicable to the forming device and / or the battery cell or battery cell arrangement, and vice versa.

[0062] The use of indefinite articles (“a”, “an”, “one”, and “ones”), particularly in the patent claims and the description reproducing them, is to be understood as such and not as a numeral. Accordingly, terms or components introduced by these articles are to be understood as occurring at least once and, in particular, may also occur multiple times.

[0063] It should be noted as a precaution that the numerical terms used here ("first", "second", etc.) primarily serve (only) to distinguish between several similar objects, quantities, or processes, and thus do not necessarily dictate any dependency and / or sequence between these objects, quantities, or processes. Should a dependency and / or sequence be required, this is explicitly stated here, or it will be obvious to a person skilled in the art upon studying the specific configuration described. Where a component can occur multiple times ("at least one"), the description of one of these components may apply equally to all or some of the multiple components, but this is not mandatory.

[0064] The invention and its technical context are explained in more detail below with reference to the accompanying figures. It should be noted that the invention is not intended to be limited by the exemplary embodiments shown. In particular, unless explicitly stated otherwise, it is also possible to extract partial aspects of the situations described in the figures and combine them with other components and findings from the present description. It should be emphasized that the figures, and especially the depicted dimensions, are only schematic. They show: Fig. 1: a forming device according to step b) of the method in a side view in section; Fig. 2: the forming device according to Fig. 1 according to step c) of the procedure in a side view in section; Fig. 3: the forming device according to Fig. 1 and Fig. 2 according to step c) of the procedure in a side view in section; Fig. 4: the forming device according to Fig. 1 to Fig. 3 according to step d) of the procedure in a side view in section; Fig. 5: the forming device according to Fig. 1 to Fig. 4 during step d) of the procedure in a side view in section; Fig. 6: the forming device according to Fig. 1 to Fig. 5 at the end of step d) of the procedure in a side view in section; Fig. 7: the forming device according to Fig. 1 to Fig. 6 during step e) of the procedure in a side view in section; Fig. 8: the forming device according to Fig. 1 to Fig. 6 during step e) of the procedure in a side view in section; Fig. 9: the forming device according to Fig. 1 to Fig. 8 during step e) of the procedure and subsequently to Fig. 8 in a side view in section; Fig. 10: the forming device according to Fig. 1 to Fig. 9 during step e) of the procedure and subsequently to Fig. 9 in a side view in section; Fig. 11: the forming device according to Fig. 1 to Fig. 10 during step e) of the procedure and subsequently to Fig. 10 in a side view in section; Fig. 12: the forming device according to Fig. 1 to Fig. 11 during step e) of the procedure and subsequently to Fig. 11 in a side view in section; and Fig. 13: the forming device according to Fig. 1 to Fig. 12 during step e) of the procedure and subsequently to Fig. 12 in a side view in section.

[0065] The Fig. Figure 1 shows a forming device 34 according to step b) of the method in a side view in section. Fig. Figure 2 shows the forming device 34 after Fig. 1 according to step c) of the procedure in a side view in section. Fig. Figure 3 shows the forming device 34 after Fig. 1 and Fig. 2 according to step c) of the procedure in a side view in section. Fig. Figure 4 shows the forming device 34 after Fig. 1 to Fig. 3 according to step d) of the procedure in a side view in section. Fig. Figure 5 shows the forming device 34 after Fig. 1 to Fig. 4 during step d) of the procedure in a side view in section. Fig. Figure 6 shows the forming device 34 after Fig. 1 to Fig. 5 at the end of step d) of the procedure in a side view in section. The Fig. 1 to Fig. The six will be described together below.

[0066] The forming device 34 comprises a die 6 of at least two parts with a first recess 7 in a first die part 8 and a second recess 9 arranged at a distance from the first recess 7 in a second die part 10, which is designed to be hinged relative to the first die part 8, a preforming punch 14 and a punching tool 16 with punch geometries corresponding to the recesses 7, 9.

[0067] The battery cell 1, which can be produced in particular by the method, comprises a housing 2 and arranged therein a stack 3 of electrode foils 4 arranged on top of each other (see Fig. 13). The housing 2 is made from a foil material 5 by folding the foil material 5.

[0068] According to step a), the two-part die 6 is provided. The housing halves are formed from the foil material 5 using the recesses 7, 9, and are arranged on top of each other to form the housing 2 by folding the foil material 5.

[0069] According to step b), a single sheet of film material 5 is provided and arranged on the matrix 6, which is in a starting position 11, and over the recesses 7, 9 in a surface section 12. The film material 5 is flat. The film material 5 is provided as a continuous material.

[0070] The film material 5 extends along an edge of the surface section 12, parallel to the imaginary fold line 13, and beyond this surface section 12. The matrix 6 is arranged on one side of the film material 5.

[0071] According to step c), the film material 5 is first formed along an imaginary fold line 13 using a preforming die 14 in an area 15, the fold line 13 running between the recesses 7, 9. The formed area 15 of the film material 5 forms a material reservoir for the subsequent second forming of the film material 5. The fold line 13, which at this stage of the process is only imaginary and is only later realized by folding, extends exclusively along a straight line.

[0072] The preforming die 14 is formed between the recesses 7, 9 in the die 6 and is movable relative to the die 6. The preforming die 14 forms an area 15 encompassing the fold line 13. The first forming operation is performed without stretching the film material 5, i.e., without reducing the thickness of the film material 5. During the first forming operation, film material 5 is fed from outside the surface section 12 into this surface section 12. The first forming operation lengthens an extension 33 of the previously flat film material 5, located between the recesses 7, 9, by at least 30%.

[0073] On the other side of the film material 5, i.e., opposite the die 6, a metal holder 18 is arranged, which fixes the film material 5 in a predetermined position on the die 6. The metal holder 18 allows the film material 5 to be fed into the surface section 12 during the initial forming process. The film material 5 is fed into the surface section 12 from only one direction: from a supply device 23 located outside the surface section 12, in this case a roll on which the film material 5 is wound as a continuous material. This allows other areas of the film material 5 to be fixed by the metal holder 18 and the die 6. The preforming punch 14 deforms the film material 5 towards the metal holder 18.

[0074] During step c), a quantity of film material used for the material reservoir is fed from outside surface section 12 into surface section 12. This allows the film material 5 to be stretched during the second forming process, ensuring sufficient material thickness for deep drawing in this area and preventing the formation of cracks in the housing 2 or in the film material 5 during subsequent operation of the battery cell 1.

[0075] The sheet metal holder 18 is provided before step d) and immediately before step c). The sheet metal holder 18 fixes the foil material 5 in step x) in the surface section 12 after step c). The foil material 5 is fixed only in those areas of the surface section 12 that do not impede the feeding of the foil material 5 into the surface section 12.

[0076] The film material 5 is trimmed between steps x) and d) so that the film material 5 extends only over the area section 12. The trimming is carried out by a first cutting device 22, which separates the film material 5 arranged between the die 6 and the punch tool 16 from the film material 5 arranged outside the area section 12.

[0077] The separation is effected, for example, by lowering the die 6 and punch tool 16 relative to the first cutting device 22. As a result of the lowering, die inserts 26 are inserted into recesses of the die 5, so that within the surface section 12 and outside the recesses and the area 15 a flat contact surface of the die 6 for the film material 5 is ensured.

[0078] The die 6 and the preforming punch 14 are movably mounted via different springs 25, so that independent movement of the die 6 and the preforming punch 14 is possible.

[0079] According to step d), a punch tool 16 is provided with punch geometries corresponding to the recesses 7, 9. The punch tool 16 is used to perform a second forming of the film material 5 in the area of ​​the recesses 7, 9, whereby during the second forming the film material 5 present in the material reservoir is moved towards the recesses 7, 9.

[0080] The punching tool 16 is positioned on the same side of the foil material 5 as the sheet metal holder 18. The foil material 5 is formed by the punching tool 16 towards the die 6.

[0081] As a result of the displacement of the film material 5 present in the material reservoir, the deep-drawing capability of the film material 5 is significantly improved. Stretching of the film material 5 in the area of ​​the recesses 7, 9 can thus be reduced. During the second forming process, the material reservoir is completely dissolved again (see Fig. 5), so that the extension 33 of the foil material 5 located between the recesses 7, 9 is returned to the state it was in immediately before the first forming process.

[0082] Heating elements 24 are arranged along the recesses 7, 9 in the die 6, which can heat the film material 5 for the second forming process, at least in certain areas. As a result of heating the film material 5, the deep drawing of the film material 5 in the area of ​​the lateral boundaries of the recesses 7, 9 can be improved and the risk of cracking of the film material 5 can be further reduced.

[0083] During step d), a third forming operation is performed on the film material 5 in the area of ​​fold line 13, in which a bending radius 19 is pressed into the film material 5 along fold line 13. This third forming operation is carried out with the preforming die 14, which further forms the area already formed by the first forming operation. The third forming operation takes place before the second forming operation, i.e., before the forming of the film material 5 in the area of ​​the cutouts 7, 9. The punch tool 16, which interacts with the preforming die 14, is used to form the bending radius 19.

[0084] The second forming operation occurs concurrently with the third. The third forming operation only takes place when, as a result of the second forming operation, at least 99% of the material reservoir formed by the first forming operation has been displaced from area 15 and towards the recesses 7 and 9. The second and third forming operations of the film material 5 are completed simultaneously. The bending radius 19 imprinted by the third forming operation defines the fold line 13, so that the folding of the film material 5 according to step e) occurs automatically along the fold line 13.

[0085] During the second forming process, the film material 5 is trimmed to define the final geometry of the edge areas 17. This trimming or cutting is performed by a second cutting device 28, which is integrated into the die 6 and the punch tool 16. The cutting process occurs concurrently with the second forming process.

[0086] Fig. 7 shows the forming device 34 after Fig. 1 to Fig. 6 during step e) of the procedure in a side view in section. Fig. Figure 8 shows the forming device 34 after Fig. 1 to Fig. 6 during step e) of the procedure in a side view in section. Fig. Figure 9 shows the forming device 34 after Fig. 1 to Fig. 8 during step e) of the procedure and subsequently to Fig. 8 in a side view in section. Fig. Figure 10 shows the forming device 34 after Fig. 1 to Fig. 9 during step e) of the procedure and subsequently to Fig. 9 in a side view in section. Fig. Figure 11 shows the forming device 34 after Fig. 1 to Fig. 10 during step e) of the procedure and subsequently to Fig. 10 in a side view in section. Fig. Figure 12 shows the forming device 34 after Fig. 1 to Fig. 11 during step e) of the procedure and subsequently to Fig. 11 in a side view in section. Fig. Figure 13 shows the forming device 34 after Fig. 1 to Fig. 12 during step e) of the procedure and subsequently to Fig. 12 in a side view in section. The Fig. 7 to Fig. The 13 points are explained together below. The explanations regarding the Fig. 1 to Fig. 6 is referred to.

[0087] Before step e), the punch tool 16 is removed from the recesses 7, 9. The sheet metal holder 18 is also removed from the die 6.

[0088] According to step e), the stack 3 is arranged in the foil material 5 and the foil material 5 is sealed in all edge areas 17 (except for the edge area 17 formed by the folding) to form the housing 2 and to complete the battery cell 1.

[0089] In step e), after the stack 3 has been arranged in the first recess 7, the second die part 10 is folded onto the first die part 8. As a result of the folding movement, the film material 5 is folded along the fold line 13. The die parts 8 and 10 are connected to each other via a (rotary) joint 31. During the folding movement, the film material 5 is fixed in the second recess 9 via a vacuum connection 27.

[0090] During step e), after the stack 3 is arranged, the film material 5 is folded over the fold line 13, so that the film material 5 is folded over itself in the edge areas 17 and a closed volume of the housing 2 is formed. The stack 3 is arranged in the areas of the film material 5 corresponding to the recesses 7, 9, which are formed as a result of the second forming process. These areas, shaped according to the recesses 7, 9, are aligned with each other as a result of the folding, so that a volume for receiving the stack 3 is formed by the folded film material 5.

[0091] The stack 3 is aligned to the first recess 7 via the electrode foils 4's guide pins, so that a position of the stack 3 is fixed relative to the foil material 5 and to the die 6. The alignment is achieved by a positioning device 29 with rod elements arranged in the die 6, between which the guide pins 30 are positioned during the arrangement of the stack 3 in the first recess 7.

[0092] The first die part 8 and the second die part 10, together with the folded film material 5 and the stack 3, are pivoted into a sealing position 20 in one step y), and in the sealing position 20 the edge region 17 of the film material 5 is sealed. The die inserts 26 are not pivoted, so that these areas of the die 6 and, via these areas of the die 6, the edge regions 17 of the film material 5 are now accessible to a sealing tool 32.

[0093] After step y), the die parts 8 and 10 are pivoted back to their starting position 11, and the battery cell 1 is removed from the die 6. The housing 2 is formed by a film material 5 that has a fold line 13 along one side surface 21 of the housing 2. A sealing seam is neither present nor required there. Reference symbol list 1 battery cell 2 cases 3 stacks 4 electrode foil 5 foil material 6 die 7 first exception 8 first matrix part 9 second recess 10 second matrix part 11 Starting position 12 Area section 13 fold line 14 preform stamps 15 area 16 stamping tools 17 Edge area 18 sheet metal holders 19 bending radius 20 Seal position 21 side surface 22 first cutting device 23 Provisioning device 24 heating elements 25 springs 26 matrix inserts 27 Vacuum connection 28 second cutting device 29 Positioning device 30 drains 31 joint 32 sealing tools 33 Extension 34 Forming device QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] WO 2012 / 022448 A1

[0008] EP 3611775 A1

[0009] DE 102018104554 A1

[0010]

Claims

[1] A method for manufacturing a battery cell (1), comprising at least a housing (2) and at least one stack (3) of electrode foils (4) arranged therein, wherein the housing (2) is made from a foil material (5) by folding the foil material (5); wherein the method comprises at least the following steps: a) Providing a matrix (6) consisting of at least two parts, with at least one first recess (7) in a first matrix part (8) and a second recess (9) arranged at a distance from the first recess (7) in a second matrix part (10), which is designed to be hinged relative to the first matrix part (8); b) Arranging at least one film material (5) on the matrix (6) in a starting position (11) and over the recesses (7, 9) in a surface section (12); c) first forming of the film material (5) along an imaginary fold line (13) with a preforming die (14) or a preforming device in an area (15), wherein the fold line (13) runs between the recesses (7, 9); wherein the formed area (15) of the film material (5) forms a material reservoir for the subsequent second forming of the film material (5); d) second forming of the foil material (5) in the area of ​​the recesses (7, 9) with a punch tool (16) with punch geometries corresponding to the recesses (7, 9), wherein during the second forming the foil material (5) present in the material reservoir is moved towards the recesses (7, 9); e) Arranging the at least one stack (3) in the foil material (5) and sealing the foil material (5) in an edge area (17) to form the housing (2) and to complete the battery cell (1). [2] Method according to claim 1, wherein during step c) an amount of film material used for the material reservoir is at least partially fed from outside the surface section (12) into the surface section (12). [3] Method according to one of the preceding claims, wherein before step d) a sheet metal holder (18) is provided which fixes the foil material (5) in step x) in the surface section (12) after step c). [4] Method according to claim 3, wherein the film material (5) is trimmed between steps x) and d) so that the film material (5) extends only over the surface section (12). [5] Method according to one of the preceding claims, wherein during step d) an additional third forming of the film material (5) takes place in the area of ​​the fold line (13) in which a bending radius (19) is embossed into the film material (5) along the fold line (13). [6] Method according to one of the preceding claims, wherein in step e) the second die part (10) is folded onto the first die part (8) after the stack (3) has been arranged in the first recess (7); wherein as a result of the folding movement the film material (5) is folded along the fold line (13). [7] Method according to claim 6, wherein in step y) the first die part (8) and the second die part (10) together with the folded film material (5) and the stack (3) are pivoted into a sealing position (20) and in the sealing position (20) the edge area (17) of the film material (5) is sealed. [8] Method according to claim 7, wherein after step y) the die parts (8, 10) are pivoted back to the starting position (11) and the battery cell (1) is removed from the die (6). [9] Forming device (34) for manufacturing a housing (2) of a battery cell (1), wherein the forming device (34) is designed to carry out the method according to one of the preceding claims, wherein the forming device (34) at least • a matrix (6) consisting of at least two parts, with at least one first recess (7) in a first matrix part (8) and a second recess (9) arranged at a distance from the first recess (7) in a second matrix part (10), which is designed to be hinged relative to the first matrix part (8); • a preforming die (14) or a preforming device as well as • a punch tool (16) with punch geometries corresponding to the recesses (7, 9). [10] Battery cell (1), at least comprising a gas-tight housing (2) produced by the method according to one of the preceding claims or by the forming device (34) according to claim 9 and at least one stack (3) of electrode foils (4) arranged therein; wherein the housing (2) is formed by a foil material (5) which has a fold line (13) along a side surface (21) of the housing (2).

Images