Method for manufacturing a battery system and motor vehicle with battery system

Abstract

The invention relates to a method for manufacturing a battery system with a plurality of battery cells (12, 16), wherein a first pole element (10) of a first battery cell (12) is electrically connected to a second pole element (14) of a second battery cell (16). A pole connector element (18) is welded to the first pole element (10) and to the second pole element (14) by means of a resistance welding process. The battery cells (12, 16) are arranged with their pole elements (10, 14) facing each other such that a gap (24) is formed between a first contact surface (20) of the first pole element (10) and a second contact surface (22) of the second pole element (14), into which the pole connector element (18) is inserted before welding.

Description

[0001] The invention relates to a method for manufacturing a battery system and a motor vehicle with a battery system manufactured according to this method.

[0002] In the production of battery systems with multiple battery cells, connecting the terminals of the individual cells presents a particular challenge. Typically, to attach the terminal connectors, the battery cells must be arranged so that the terminals of each cell are easily accessible. Terminal connectors can then be welded flat onto the battery terminals, for example, using laser welding processes. These designs become particularly expensive when the terminal connectors need to be able to handle high currents between the connected terminals. This is often required, especially in high-performance battery systems, such as those used in motor vehicles.

[0003] German patent application DE 10 2019 127 703 A1 discloses a battery system in which a plurality of pouch cells are electrically connected to each other by cell connectors. The cell connectors have tongues made of different materials which are welded to the terminals of the individual cells.

[0004] DE 10 2012 025 004 A1 discloses a memory cell pack comprising a plurality of electrical memory cells arranged in a housing and interconnected by means of pole connectors. The memory cells have pole terminals that are materially bonded to the pole connectors by laser welding.

[0005] DE 10 2016 000 843 A1 shows an energy storage device comprising a plurality of energy storage cells. The energy storage cells include cell poles that are connected in pairs by cell pole connectors.

[0006] US Patent 2022 / 0367978A1 discloses a battery assembly and a method for assembling the assembled battery. The assembled battery comprises a first battery, a second battery, and a busbar. The first battery includes a first terminal assembly. The second battery includes a second terminal assembly. The busbar is bent into a first section, a second section, and a third section. The first section is connected to the first terminal assembly, and the third section is connected to the second terminal assembly. The busbar is an integrated U-shaped structure.

[0007] US Patent 2014 / 0205889A1 discloses a battery module comprising a first battery cell, a second battery cell, and a connector element that connects the first and second connector sections. The connector element comprises a first contact section, wherein the first contact section has a first mating section that is in contact with the first connector section, and a second contact section, wherein the second contact section has a second mating section that is in contact with the second connector section.

[0008] The invention is based on the objective of demonstrating a cost-effective method for manufacturing a battery system with a plurality of battery cells and a motor vehicle with a battery system manufactured according to this method.

[0009] The problem is solved by the features of the independent claims. The features of the dependent claims relate to advantageous embodiments.

[0010] The process for manufacturing a battery system with multiple battery cells involves connecting the first pole element of a first battery cell to the second pole element of a second battery cell. The pole connector element is welded to the first pole element and to the second pole element using a resistance welding process.

[0011] A pole element is understood to be, in particular, a metallic element of the battery cell that is designed and intended to enable electrical contact with an electrode of an electrochemical cell located inside the battery cell. Such pole elements are also referred to, for simplicity, as battery cell poles or terminals. A resistance welding process is understood to be a welding process in which the components being joined are heated by an electric current flowing through the joint until the welding temperature is reached.

[0012] The problem is solved in particular by arranging the battery cells with pole elements facing each other in such a way that a gap is formed between a first contact surface of the first pole element and a second contact surface of the second pole element, into which the pole connector element is inserted before welding.

[0013] This arrangement of the battery cells, and especially their terminals, allows for a particularly cost-effective electrical connection of the terminals. In particular, very inexpensive terminal connectors can be used, as these only need to bridge a small gap.

[0014] The battery cells can be, in particular, prismatic battery cells. These can be designed such that the terminal elements of the battery cells are arranged on opposite narrow sides of the battery cells. The battery cells can be arranged in rows such that the terminal elements of adjacent battery cells are in contact with each other. Such "rowed" arrangements of prismatic battery cells can thus be easily connected in series. The terminal connectors can advantageously be used to compensate for tolerances between the battery cells along the direction of the row. This applies in particular to the terminal connector design described here.

[0015] The first and second pole elements can be arranged, in particular, on mutually facing surfaces of the battery cells. These surfaces can be, in particular, the narrow sides of prismatic battery cells.

[0016] The first and second contact surfaces can be oriented, at least substantially, parallel to the facing surfaces of the battery cells. Such an orientation of the contact surfaces advantageously allows the gap to be bridged by a terminal connector element, and in particular, facilitates the insertion of the terminal connector element into the gap between the contact surfaces.

[0017] The pole connector element has a base area. The pole connector element is inserted into the gap with its base area oriented, at least substantially, parallel to the contact surfaces. The base area can be designed to be flat. Such a base area, oriented parallel to the contact surfaces, can be easily positioned in the gap between the contact surfaces.

[0018] The terminal connector element has multiple contact areas that, after insertion into the gap, make contact with the first and second contact surfaces and weld them together. This design of the terminal connector element, with a base area and multiple contact areas, allows it to be welded to the respective terminal element at multiple points using a resistance welding process. In this way, a connection between the terminal element and the terminal connector element can be created that is suitable for transmitting comparatively high electrical power. At the same time, the heat generated during resistance welding in the area of ​​the terminal elements can be kept within a range that is not critical for the battery cell.

[0019] The pole connector element can be elastically deformed during insertion into the gap in such a way that, due to the elastic stresses generated by this deformation, it bears against the contact surfaces under a mechanical preload. This preload and the resulting contact ensure, in particular, that sufficiently good electrical contact exists between the pole connector element and the contact surfaces to enable the resistance welding connection.

[0020] When inserted into the gap, the contact areas in particular can be deformed. These contact areas can be designed, for example, like tongues and / or leaf springs. Such a design allows for particularly good deformability of the contact areas, enabling them to bend elastically like leaf springs.

[0021] The contact areas can extend, particularly in the undeformed state, at an angle of at least 10°, particularly at least 20°, and / or at most 80°, particularly at most 70°, to the base area of ​​the pole connector element. The contact areas extending away from the base area extend, in particular, away from the contact area and in the opposite direction to the insertion of the pole connector element into the gap. Such an orientation makes insertion of the pole connector element into the gap particularly easy, as the contact areas can slide off the pole elements.

[0022] The pole connector element can be made of sheet metal. Sheet metal is a cost-effective semi-finished product from which the pole connector element can be manufactured, allowing for the realization of the described designs, particularly those with leaf-spring-like contact areas. The pole connector element can be manufactured by cutting, embossing, and / or bending. These methods allow sheet metal to be formed into a shape suitable for use as a pole connector element, especially the one described here.

[0023] To perform the welding, the pole connector and the pole elements can be electrically contacted, with a welding current being passed through them. Particularly in conjunction with the described design, contacting the pole connector and pole elements allows for the exploitation of the fact that the effective conductor cross-sections of the pole elements and the pole connector exhibit significantly better conductivity than the points where the pole connector and poles touch after the pole connector is inserted into the gap. Consequently, only minimal heat is generated in the pole elements and those parts of the pole connector that are not directly intended for welding.

[0024] The electrical contact of the pole connector element can be achieved, in particular, via the base area. The base area can be designed so that it remains relatively easily accessible even after the pole connector element has been inserted into the gap. Specifically, a portion of the base area can protrude from the gap between the contact surfaces after the pole connector element has been inserted. This portion of the pole connector's base area can be used for electrical contact during the welding process.

[0025] During welding, the welding current can first be passed through the first pole element and the pole connector, and then through the second pole element and the pole connector, in order to weld the pole connector to the first pole element and then to the second pole element sequentially. Such serial welding offers the advantage that the welding processes of the pole connector to the first and second pole elements can be controlled separately. This can be particularly helpful when the first and second pole elements are made of different materials.

[0026] The method can, in particular, provide for the electrical connection of the terminal connector element to a battery management system. This can, in particular, enable the balancing of the battery cells by means of the battery management system. Specifically, the base area of ​​the terminal connector element can be electrically connected to the battery management system.

[0027] The method can, in particular, provide that a plurality of battery cells are arranged in a series and the terminals of adjacent battery cells are connected with a plurality of terminal connectors using the described method, thus creating a series connection of the battery cells. In this way, compact battery systems can be created. Specifically, multiple rows, each with its battery cells connected in series, can be arranged side by side. At the ends of the rows, corresponding terminal connections can be made to connect multiple rows in series. In this way, battery systems with high usable voltages can be created.These battery systems have the particular advantage that the connections of the pole elements are extremely compact and arranged between the battery cells, so that the common outer surfaces of the arrangement formed by the surfaces of the battery cells can be used for other purposes, for example to bring planar elements into contact with them to influence the temperature of the battery cells and / or to fix the battery cells on supports.

[0028] Battery systems manufactured using the described method can be used, in particular, in motor vehicles to supply the electric drive system of the respective vehicle with electrical energy. A motor vehicle can have an electric drive system and a battery system manufactured using the described method for supplying the vehicle's drive system with electrical energy.

[0029] Further practical embodiments of the invention are described below in connection with the drawings. They show: Fig. 1 a schematic representation of exemplary battery cells before the insertion of the terminal connector element into the space, Fig. 2 a schematic representation of exemplary battery cells after the insertion of the terminal connector element into the space, Fig. 3 a schematic representation of the exemplary battery cells before welding the pole connector element to the first pole element, Fig. 4 A schematic representation of the exemplary battery cells after welding the terminal connector element to the first terminal element and before welding the terminal connector element to the second terminal element, Fig. 5 A schematic representation of the exemplary battery cells after welding the pole connector element to the second pole element.

[0030] The in the Fig. The exemplary methods shown in Figures 1 to 5 provide that a first pole element 10 of a first battery cell 12 is electrically connected to a second pole element 14 of a second battery cell 16.

[0031] In this process, a pole connector element 18 is welded to the first pole element 10 and the second pole element 14 using a resistance welding process. The actual welding process is described in the Fig. Figures 3 to 5 are shown schematically. Before welding, battery cells 12 and 16 are first separated as shown in the diagrams. Fig. Figures 1 to 5 schematically show the pole elements 10 and 14 arranged with each other facing each other such that a gap 24 is formed between a first contact surface 20 of the first pole element 10 and a second contact surface 22 of the second pole element 14. This arrangement is particularly suitable in the Fig. 1 to recognize.

[0032] The pole connector element 18 is inserted into the space 24 formed between the contact surfaces 20 and 22. Fig. Figure 1 shows the situation immediately before the pole connector element 18 is inserted into the space 24. Fig. 2 the situation immediately after the pole connector element 18 has been inserted into the space 24.

[0033] The method can, as in the example shown, provide that the first battery cell 12 and the second battery cell 16 are prismatic battery cells. In the schematic diagrams of the Fig. Figures 1 to 5 each show only one pole element 10 or 14 of the respective battery cell 12 or 16. In practice, the battery cells 12, 16 can each have two pole elements 10, 14, which can be arranged, in particular, on opposite surfaces of the battery cell 12, 16.

[0034] As in the example shown, the first pole element 10 and the second pole element 14 are arranged, in particular, on mutually facing surfaces 26 and 28 of the battery cells 12 and 16. The first contact surface 20 and the second contact surface 22 are oriented, in particular, parallel to the mutually facing surfaces 26 and 28 of the battery cells 12 and 16.

[0035] As shown in the example, the pole connector element 18 has a base area 30. The base area 30 can be designed as a flat surface. In the Fig. Figures 1 to 5 show the planar extent plane of the base area 30 oriented perpendicular to the drawing plane. As in the exemplary procedure shown, the pole connector element 18, with its planar base area 30 oriented parallel to the contact surfaces 22 and 20, can be inserted into the space 24.

[0036] The pole connector element 18 has a plurality of contact areas 32 with which, after insertion into the gap 24, the pole connector element 18 rests against the first contact surface 20 and the second contact surface 22. In the further course of the process, the pole connector element 18 can be welded to the first contact surface 20 and the second contact surface 22 as in the example shown.

[0037] In the example shown, the contact areas 32 can be designed as flat surfaces, with one plane of extension of the flat design oriented perpendicular to the drawing plane. This allows the contact areas 32 to exhibit a leaf spring-like behavior, particularly when the pole connector element 18 is inserted into the gap 24. The contact areas 32 are elastically deformed when the pole connector element 18 is inserted into the gap 24, generating elastic stresses in the contact areas 32. Due to these elastic stresses, the contact areas 32 bear against the contact surfaces 20 and 22 under mechanical preload.

[0038] To perform the welding, the pole connector element 18 and the pole elements 10 and 14 are electrically contacted, and a welding current is passed through the pole connector element 18 and the pole elements 14 and 16. This can be done, in particular, as in the example shown, by first passing the welding current through the first pole element 10 and the pole connector element 18. In the Fig. 3 and Fig. Figure 4 shows the state immediately before and immediately after the welding between pole connector element 18 and the first pole element 10. The welding process can result in the formation of weld points 34, particularly at the points where the contact areas 32 touch the first contact surface 20, as shown in the example. As in the example shown, the welding current can then be passed through the second pole element 14 and the pole connector element 18. Fig. Figure 5 shows the state immediately after the resulting welding of the pole connector element 18 to the second pole element 14. The contact areas 32 on the second contact surface 22 immediately before welding are shown as an example in Figure 5. Fig. 4, merely concerned, have in the in Fig. 5. The weld points 34 shown in the diagram are formed after welding.

[0039] The features of the invention disclosed in the present description, the drawings, and the claims can be essential for realizing the invention in its various embodiments, both individually and in any combination. The invention can be varied within the scope of the claims and taking into account the knowledge of the person skilled in the art. Reference symbol list 10 first pole element 12 first battery cell 14 second pole element 16 second battery cell 18 pole connector element 20 first contact surface 22 second contact surface 24 spaces 26 area 28 area 30 Basic area 32 Contact area 34 welding points

Claims

[1] Method for manufacturing a battery system with a plurality of battery cells (12, 16), wherein a first pole element (10) of a first battery cell (12) is electrically connected to a second pole element (14) of a second battery cell (16), wherein a pole connector element (18) is welded to the first pole element (10) and to the second pole element (14) by means of a resistance welding process, wherein the battery cells (12, 16) are arranged with pole elements (10, 14) facing each other such that a gap (24) is formed between a first contact surface (20) of the first pole element (10) and a second contact surface (22) of the second pole element (14), into which the pole connector element (18) is inserted before welding, characterized by, that the pole connector element (18) has a base area (30) with which it is oriented, at least substantially, parallel to the contact surfaces (20, 22) into the space (24) and has a plurality of contact areas (32) with which the pole connector element (18) bears against the first and second contact surfaces (20, 22) after being inserted into the space (24) and is welded to the first and second contact surfaces (20, 22). [2] Method according to claim 1, characterized by , that the first and second battery cells (12, 16) are prismatic battery cells. [3] Method according to claim 1 or 2, characterized by , that the first pole element (10) and the second pole element (14) are arranged on mutually facing surfaces of the battery cells (12, 16). [4] Method according to any of the preceding claims, characterized by, that the first and second contact surfaces (20, 22) are oriented, at least substantially, parallel to the mutually facing surfaces of the battery cells (12, 16). [5] Method according to any of the preceding claims, characterized by , that the base area (30) is designed to be flat. [6] Method according to any of the preceding claims, characterized by , that the pole connector element (18), in particular the contact areas (32) of the pole connector element (18), is elastically deformed when inserted into the space (24) in such a way that, due to elastic stresses generated by the elastic deformation in the pole connector element (18), in particular in the contact areas (32), it bears against the contact surfaces (20, 22) under a mechanical preload. [7] Method according to any of the preceding claims, characterized by, that to carry out the welding, the pole connector element (18) and the pole elements (10, 14) are electrically contacted and a welding current is passed through the pole connector element (18) and the pole elements (10, 14), in particular wherein the welding current is first passed through the first pole element (10) and the pole connector element (18) and then through the second pole element (14) and the pole connector element (18) in order to weld the pole connector element (18) successively first to the first pole element (10) and then to the second pole element (14). [8] Method according to any of the preceding claims, characterized by , that the pole connector element (18), in particular the base area (30) of the pole connector element (18), is electrically connected to a battery management system, in particular to enable the performance of a balancing of the battery cells (12, 16) by means of the battery management system. [9] Method according to any of the preceding claims, characterized by , that a plurality of battery cells (12, 16) are arranged in a series and the pole elements (10, 14) of adjacent battery cells (12, 16) are connected with a plurality of pole connector elements (18) by means of a method according to one of the preceding claims, so that a series connection of the battery cells (12, 16) is brought about. [10] Motor vehicle with an electric drive and a battery system produced by a method according to one of the preceding claims for supplying the drive of the motor vehicle with electrical energy.

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