Method for manufacturing a lid assembly of a battery cell and lid assembly

Abstract

The invention relates to a method for manufacturing a cover assembly (1a, 1b) of a battery cell comprising a cover part (2) and two terminal feedthroughs (3, 4, 5, 6) arranged in two openings (7, 8) of the cover part, each insulated, comprising the following steps: manufacturing the cover part with the openings and the terminal feedthroughs arranged in the openings at a distance from the edges of the openings using an additive manufacturing process on a base (9); then adding a solid insulation (10, 11) between the terminal feedthroughs and the material of the cover part; and finally separating the additively manufactured material of the cover part and the terminal feedthroughs from each other and / or from the base. This method design eliminates the need for a custom mold when adding the solid insulation.

Description

[0001] The invention lies in the field of electrical engineering, mechanics and materials science and can be used with particular advantage in the production of battery cells.

[0002] With the increasing electrification of almost all areas of life and the demand for mobility, supplying units or devices with electrical energy through mobile electrochemical energy storage devices is becoming an increasingly common requirement. Accordingly, the development and further development of electric battery cells is a rapidly advancing field of technology.

[0003] Many battery cells are encapsulated and feature metal enclosures, each of which has a shell / base element and a lid that are connected to each other. Insulated terminal feedthroughs are often provided in the lid area, allowing access and contact to the terminals—the battery cell's electrical contacts—on the outside of the lid.

[0004] Due to the high volumes typically required for production, the development of cost-effective manufacturing processes for such battery cells or their components is of great interest.

[0005] For example, German patent specification DE102018209270B4 discloses a method for assembling various elements of a cover assembly for a battery cell.

[0006] For this purpose, individual elements are placed into an injection mold, positioned by the mold, and then overmolded.

[0007] From the published patent application DE102018200148A1 a cover assembly is known in which the special geometric structure allows the bonding of a terminal feedthrough to a cover part to be designed in a suitable manner.

[0008] From the published patent application DE102020206664A1, methods for producing a component with a conductor track in a common additive manufacturing process are known.

[0009] Against the background of the prior art, the present invention is based on the object of creating an efficient and particularly flexible method for the production of cover assemblies for battery cells.

[0010] The problem is solved by the invention with the features of the independent patent claims. The dependent patent claims present possible embodiments of the solution.

[0011] Accordingly, the invention relates to a method for producing a cover assembly of a battery cell with a cover part and at least one, in particular two terminal feedthroughs, which are each arranged in an insulated manner in at least one, in particular two openings of the cover part, with the following steps: Production of the cover part with the openings as well as terminal feedthroughs arranged in the openings at a distance from the edges of the openings in an additive manufacturing process on a base, then adding a solid insulation between the terminal bushings and the material of the cover part, and then separating the material of the cover part and the terminal feedthroughs, which was built up using the additive manufacturing process, from each other and / or from the base.

[0012] In known manufacturing processes, the individual parts, i.e. a cover part and one or more terminals or terminal feedthroughs, are often positioned relative to one another in an injection molding process and then overmolded together to create an electrically insulating and gas-tight connection between the cover part and the terminal feedthroughs. By producing the aforementioned elements in an additive manufacturing process, these elements are built up on one another on a, in particular common, base and are firmly connected to this. Typically, such additive manufacturing processes connect one layer or layer of structural elements to the layer below it, with the first layer of structural elements being connected to the base. Structural elements can, for example, be solid particles of a powder or drops of a liquid that solidifies on cooling, or the like.Solid particles are typically bound with a binder in droplet form, which is selectively and precisely printed into each layer to form the desired shape. Laser melting processes are also known, in which a powder layer is selectively melted and solidified by laser exposure.

[0013] By firmly and stably positioning the elements of the cover assembly relative to one another, either by connecting them to one another or by using a common base, the gaps between the terminal feedthroughs and the openings in the cover part are reliably defined, allowing the entire assembly to be overmolded with an electrically insulating material without the need for a customized injection mold for positioning. Punching or manufacturing a cover sheet and a terminal feedthrough is also eliminated, meaning no tools are required. The manufacturing process described is therefore particularly suitable for fast, flexible, and customizable production of cover assemblies, either for small-batch production or for rapid prototyping in development work.

[0014] For this purpose, a special design of the solution can provide for the solid insulation, particularly in liquid form, to be introduced into the gap between the terminal bushings and the material of the cover part and solidified. Various methods for introducing the insulation are conceivable, for example, as explained above, overmolding the parts of the cover assembly, but also the targeted injection of a liquid insulating material without pressure and using capillary forces to draw the material into the gap.

[0015] It may further be provided that the solid insulation is a polymer or a thermoplastic material.

[0016] The solid insulation material can then harden through cooling in the case of a thermoplastic, through polymerization in the case of a polymer, through another chemical reaction, or through drying. The surface roughness created by the additive manufacturing process can contribute to good adhesion of the insulating material to the surfaces of the parts of the cover assembly. For example, in the case of polymers, heating or irradiation of the insulating material can be used to solidify it.

[0017] A further embodiment may provide that the material of the cover part and the terminal feedthroughs constructed in the additive manufacturing process is separated from each other and / or from the base by erosion or machining.

[0018] In this way, the separation of the cover part from the terminal bushings can be carried out with little effort, especially when separating by erosion processes, so that the connections of the parts with the solid insulation are deformed or stressed by the effect of force as little as possible.

[0019] In addition, an embodiment can provide that a bursting device is formed in the cover part by the additive manufacturing process in that a bursting region of the cover part is formed with a smaller wall thickness than the remaining regions of the cover part, wherein in particular the wall thickness in the bursting region is formed so thin that it breaks at a pressure above 8 bar.

[0020] For example, it can be provided that the wall thickness in the bursting area is limited to a range of 0.1 mm to 0.2 mm during the additive manufacturing process, or that the wall thickness is reduced later, particularly using a machining process, to a range between 0.1 mm and 0.2 mm. An opening can also be introduced into the cover part during the additive manufacturing process or later, into which a prefabricated bursting device is inserted.

[0021] Typically, bursting elements are inserted into lid components that burst at a defined pressure. The production of such bursting elements requires a high level of manufacturing precision, which can be achieved directly with additive manufacturing processes, so that corresponding bursting devices can be formed directly using the additive manufacturing process.

[0022] It may also be provided that when constructing the cover assembly, one of the terminal bushings is constructed from pure aluminum and / or one of the terminal bushings is constructed from pure copper.

[0023] A further embodiment may include the possibility that the additive manufacturing process is designed as powder bed-based melting, in particular powder bed-based laser beam melting or electron beam melting.

[0024] The use of these pure metals results in a low electrical resistance of the terminal bushings, but requires a certain amount of increased effort in the case that the terminal bushings are manufactured using the laser beam melting method, since the laser wavelengths must be adapted to the absorption spectrum of the material to be heated, melted and solidified.

[0025] On the other hand, the powder-bed laser melting process, under certain conditions, enables the simple production of various separate elements from different starting materials using additive manufacturing. For this purpose, the powder must be selectively applied and solidified during the manufacturing process depending on the elements to be produced and their materials.

[0026] In one embodiment of the solution, it can further be provided that a filling opening for an electrolyte is provided in the cover part by means of a recess in the additive manufacturing process or by means of subsequent machining.

[0027] After the lid assembly has been assembled and joined with the remaining parts of a battery cell housing, this opening is used to fill the housing with liquid electrolyte. The opening can then be sealed gas-tight with a welded seal or with a precisely fitting plug.

[0028] In addition, an embodiment of the method can provide that the material of at least one of the terminal feedthroughs is subjected to a heat treatment after the additive manufacturing process.

[0029] Such heat treatment, which may include, for example, simple or repeated heating and cooling of the terminal bushings, achieves optimized electrical conductivity in the sense of minimized electrical resistance.

[0030] In addition to a method for producing a cover assembly, the invention also relates to a cover assembly of a battery cell with a cover part consisting of a metal and at least one, in particular two terminal feedthroughs consisting of different metallic materials, which are each electrically insulated and gas-tightly inserted into at least one, in particular two openings of the cover part by means of a solid insulation, wherein both the cover part and the terminal feedthroughs are manufactured in a common additive manufacturing process.

[0031] In the following, the invention is shown and subsequently explained using exemplary embodiments in figures of a drawing.

[0032] This shows Fig. 1 schematically shows in a perspective view the design of a cover assembly with a cover part and terminal bushings according to the prior art, Fig. 2: a sectional view according to a manufacturing process according to the prior art, Fig. 3: a cross-sectional view of a manufactured cover assembly according to the prior art after inserting the terminal bushings into the openings of the cover part, Fig. 4: a cross-sectional view of a cover part according to the invention and terminal bushings during production in an additive manufacturing process on a base, Fig. 5: the elements from the Fig. 4 after adding an insulating material into the gap between terminal bushings and cover part Fig. 6: the representation from the Fig. 5 with the indication of the dividing line where the manufactured elements are separated from the base, as well as Fig. 7: the lid assembly after separation from the base.

[0033] The Fig. Figure 1 shows a perspective and exploded view of a box-shaped, prismatic housing 16 of a battery cell according to the prior art, the production of which can be optimized by the invention. In principle, however, the invention is also applicable to cylindrical or other-shaped battery cells. The housing can contain a battery winding and, in the closed state after assembly, a filling with a liquid or gel-like electrolyte. Above the housing part 16, a cover part 2 is shown, which, in the finished state, is placed onto the housing part 16 and welded to it in a gas-tight manner.

[0034] The cover part features two openings 7, 8 into which electrically insulated terminal bushings 3, 4 are inserted. The terminal bushings are connected to current collectors 3a, 4a, which are connected to the terminals of the battery winding inside the housing 16. The current collectors can be manufactured together with the terminal bushings using the additive manufacturing process or can be attached to the terminal bushings later, for example, by laser welding.

[0035] The lid also features a bursting device 12 and a filler opening 13 for a liquid electrolyte. After the electrolyte has been added, the filler opening 13 is sealed gas-tight, for example, by welding or a suitable plug. For this purpose, the filler opening is manufactured to precise dimensions.

[0036] The bursting device 12 has a bursting region in which the wall thickness of the cover part is reduced compared to the adjacent regions to a thickness which, when a defined pressure threshold in the housing is exceeded, results in the wall breaking in this region. Since both the material parameters and the material thickness can be easily adjusted using the additive manufacturing process, the bursting pressure of the bursting device can be reliably set. Alternatively or additionally, the wall thickness in this region can also be reduced by an abrasive process, in particular a machining process, to a final thickness which is, for example, between 0.1 mm and 0.2 mm. A further variant can provide that the additive process or machining creates an opening into which a prefabricated bursting device, for example with a bursting membrane, is inserted, in particular welded.

[0037] If machining is planned, this can also be extended to include post-machining the finished cover part as a whole in order to reduce the roughness of the surface.

[0038] In the Fig. Figure 2 shows a sectional view of a cover part 2 with openings 7, 8 for the terminal bushings 3, 4, which are not yet inserted into the openings in this illustration. According to the state of the art, the terminal bushings are manufactured separately from the cover part 2 and inserted into it, as shown in Fig. 3. According to the state of the art, the Fig. 2 and Fig. 3 are fixed relative to one another in an injection mold before an insulating injection molding material is injected in order to electrically insulate and seal the gaps between the terminal bushings 3, 4 and the edges of the openings 7, 8 in a gas-tight manner.

[0039] In the Fig. 4 shows a cover part 2 and terminal feedthroughs 5, 6 according to the invention within the framework of an additive manufacturing process in a state in which they are constructed on a base 9 and are still firmly connected to it. The additive manufacturing process used is a multi-material powder bed laser beam melting process, which allows several different materials to be separately melted in the powder bed, which are locally selectively melted with the laser and solidify upon subsequent cooling.

[0040] Due to the fixed positioning relative to each other, the gaps between the terminal bushings 5, 6 and the edges of the openings 7, 8 are precisely defined and fixed. In this state, the gaps can be filled with an insulating material by gluing, potting, or injection molding and electrically sealed. This is Fig. 5 is symbolically indicated by an injection mold 17. After solidification, the insulation material fixes and secures the aforementioned elements relative to each other. This eliminates the need for a customized injection mold for encapsulation and fixation, which is costly and time-consuming to manufacture. The process described allows for customized cover assemblies to be designed and manufactured quickly.

[0041] In the Fig. 6, the arrows 14, 15 indicate the line along which the elements 2, 5, 6 constructed by means of the additive manufacturing process are separated from the base 9.

[0042] The terminal bushings can be made of pure aluminum (cathode) and pure copper (anode) to achieve optimized electrical conductivity. Pure copper or aluminum does not refer to a chemically pure element, but rather to the respective element with the unavoidable impurities common in industrial environments, not an alloy.

[0043] The terminal bushings are, as in Fig. 7, connected to current collectors 5a, 6a or manufactured together with them in the additive manufacturing process, which are connected to the terminals of the battery coil inside the housing 16.

[0044] The cover part also features a bursting device 12 and a filling opening 13 for a liquid electrolyte. The filling opening 13 is sealed gas-tight after the electrolyte has been added, for example, by welding or a suitable plug. For this purpose, the filling opening is manufactured to precise dimensions, either during additive manufacturing itself or later by inserting a precision hole.

[0045] The bursting device 12 can be implemented by a thinner area than the other areas of the plate-shaped cover part, the material thickness of which can be precisely adjusted using the additive manufacturing process to ensure rupture at a defined pressure. Alternatively or in addition to a thinner design, post-processing by milling or another abrasive, particularly machining, process can also be provided in this area. In addition, notches can also be provided in the thin-walled area to facilitate adjustment of the bursting pressure.

[0046] After completion of the cover assembly, it is welded gas-tight to the battery cell housing, and the liquid electrolyte is poured through opening 13. Opening 13 is then sealed gas-tight, for example, by welding. QUOTES CONTAINED IN THE DESCRIPTION

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

[0000] DE102018209270B4

[0005] DE102018200148A1

[0007] DE102020206664A1

[0008]

Claims

[1] Method for producing a cover assembly (1a, 1b) of a battery cell with a cover part (2) and at least one, in particular two terminal feedthroughs (3, 4, 5, 6), which are each arranged in an insulated manner in at least one, in particular two openings (7, 8) of the cover part, with the following steps: Production of the cover part with the openings as well as terminal feedthroughs arranged in the openings at a distance from the edges of the openings in an additive manufacturing process on a base (9), then adding a solid insulation (10, 11) between the terminal bushings and the material of the cover part, and then separating the material of the cover part and the terminal feedthroughs, which was built up using the additive manufacturing process, from each other and / or from the base. [2] Method according to claim 1, characterized bythat the solid insulation (10, 11), in particular in liquid form, is introduced into the space between the terminal bushings (3, 4, 5, 6) and the material of the cover part (2) and solidified. [3] Method according to claim 2, characterized by that the solid insulation (10, 11) is a polymer or a thermoplastic material. [4] Method according to one of claims 1 to 3, characterized by that the material of the cover part (2) and the terminal bushings (3, 4, 5, 6) built up in the additive manufacturing process is separated from each other and / or from the base by erosion or machining. [5] Method according to one of claims 1 to 4, characterized bythat a bursting device (12) is formed in the cover part (2) by the additive manufacturing process in that a bursting region of the cover part is formed with a smaller wall thickness than the other regions of the cover part, wherein in particular the wall thickness in the bursting region is formed so thin that it breaks at a pressure above 8 bar. [6] Method according to one of claims 1 to 5, characterized by that when constructing the cover assembly (1a, 1b) one or both of the terminal bushings (3, 4, 5, 6) are constructed from pure aluminum or an aluminum alloy and / or one or both of the terminal bushings are constructed from pure copper or a copper alloy. [7] Method according to one of claims 1 to 6, characterized by that the additive manufacturing process is designed as powder bed-based melting. [8] Method according to one of claims 1 to 3, characterized bythat a filling opening (13) for an electrolyte is provided in the cover part (2) by means of a recess in the additive manufacturing process or by subsequent machining. [9] Method according to one of claims 1 to 8, characterized by that the material of at least one of the terminal bushings (3, 4, 5, 6) is subjected to a heat treatment after the additive manufacturing process. [10] Cover assembly (1a, 1b) of a battery cell with a cover part (2) made of a metal and at least one, in particular two terminal feedthroughs (3, 4, 5, 6) made of different metallic materials, which are each electrically insulated and inserted gas-tight into at least one, in particular two openings (7, 8) of the cover part by a solid insulation (10, 11), characterized by that both the cover part and the terminal bushings are manufactured using a common additive manufacturing process.

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