Welding device for welding electrodes of two adjacent battery cells of a battery, battery and method for manufacturing a battery

Abstract

Welding device for welding electrodes (221, 222, 223, 224, 225, 226, 227, 228) of two adjacent battery cells of a battery (10) with a hold-down device (42), which is designed to press the two electrodes to be welded (221, 222, 223, 224, 225, 226, 227, 228) of the adjacent battery cells (201, 202, 203, 204, 205, 206, 207, 208) together in such a way that the overlapping electrodes (221, 222, 223, 224, 225, 226, 227, 228) are in contact with each other, and a welding unit (50), which is designed to press two overlapping electrodes (221, 222, 223, 224, 225, 226, 227, 228) together by the hold-down device. (42) to weld together electrodes (221, 222, 223, 224, 225, 226, 227, 228) of adjacent battery cells (201, 202, 203, 204, 205, 206, 207, 208) pressed together, wherein the hold-down device (42) is configured to weld the electrodes (221, 222, 223, 224, 225, 226, 227, 228) to one of the battery cells (201, 202, 203, 204, 205, 206, 207,208) receiving end plate (30) of the battery (10) detachably attached and bearing against at least one spacer (321, 322) provided on the end plate (30), wherein the end plate (30) has a hold-down counterpart (421, 422, 423, 424) corresponding to the hold-down, wherein the hold-down (42) has a pressure element (461, 462, 463, 464) axially pre-tensioned via a spring element (471, 472, 473, 474), which loads the electrodes (221, 222, 223, 224, 225, 226, 227, 228) to be welded together, and wherein the overlapping electrodes (221, 222, 223, 224, 225, 226, 227, 228) to be welded together 223, 224, 225, 226, 227, 228) are compressed between the hold-down (42) and the hold-down counterpart (421, 422, 423, 424), wherein the hold-down (42) is arranged to be fastened to the end plate (30) by at least one screw (44, 46).

Description

[0001] The invention relates to a welding device for welding electrodes of two adjacent battery cells of a battery, comprising a clamping device configured to press the two electrodes of the adjacent battery cells to be welded together such that the overlapping electrodes are in contact with each other, and a welding unit configured to weld two overlapping electrodes of the adjacent battery cells together, which are pressed together by the clamping device. The invention further relates to a battery and a method for manufacturing a battery.

[0002] Batteries, especially high-voltage batteries for use as energy storage devices to power hybrid or electric vehicles, typically comprise several battery cells, each having a negative electrode and a positive electrode. When connecting the battery cells to form a battery, the electrodes can either be electrically connected via cell connectors or welded directly together. A welded connection advantageously exhibits low electrical contact resistance and enables a permanently stable connection between the electrodes.

[0003] The electrodes of adjacent battery cells are welded together by a welding device, such a device being disclosed, for example, in EP 3 305 460 A1. The welding device has a movable welding unit by which an electrode of a first battery cell is welded to an electrode of a second battery cell adjacent to the first battery cell. The electrode of the first battery cell and the electrode of the second battery cell overlap, and the weld is formed by the welding unit acting on the overlapping area of ​​the two electrodes. Furthermore, the welding device has a hold-down device attached to the welding unit. The hold-down device acts on the overlapping electrodes to be welded and presses them together so that the electrodes are in contact with each other.The welding unit is then activated and the electrodes are welded together.

[0004] A disadvantage of this type of welding device is that the hold-down device is attached to the welding unit, resulting in a relatively high weight to be moved and the associated drive power required to power the welding unit. Furthermore, the welding unit must perform numerous traversing movements to connect all the battery cells into a battery, during which the hold-down device is continuously moved along with it.

[0005] The object of the invention is to create a welding device with reduced drive power and reduced energy consumption.

[0006] This problem is solved by an energy storage device for a motor vehicle having the features of independent claim 1.

[0007] By having the electrode clamp detachably attached to an end plate of the battery that holds the battery cells, and by having a corresponding clamp counterpart, and by having the overlapping electrodes to be welded compressed between the clamp and the clamp counterpart, a welding device is created that requires reduced drive power and thus has reduced energy consumption. Furthermore, the weight to be moved by a drive device is reduced, since the clamp is fixed to the end plate and does not need to be moved during the entire welding process. In addition, the welding unit has a reduced installation space, which increases its freedom of movement.

[0008] The clamp is attached to the battery's end plate before the welding process. Its attachment to the end plate alone presses the two electrodes of adjacent battery cells together. The clamp presses the two electrodes against the corresponding clamp on the end plate, thus clamping the electrodes between the clamp and the clamp. After the clamp is attached, the welding unit is activated, welding the overlapping electrodes together in the overlap area. Following the welding process, the clamp is removed.

[0009] Preferably, the hold-down clamp has a clamping section on its side facing the end plate, with which the hold-down clamp rests against the overlapping electrodes, the welding unit being arranged on a side of the hold-down clamp facing away from the end plate, the hold-down clamp having a through-opening through which a welding jet from the welding unit extends. The through-opening is arranged in the area of ​​the overlapping electrodes to be welded together.

[0010] Preferably, the hold-down device can be fastened to the end plate by at least one screw, allowing for simple and cost-effective detachable connection of the hold-down device to the end plate. The hold-down device has a through-hole, and the end plate has a threaded hole, with the screw head resting against the hold-down device and the screw shank extending through the through-hole and screwed into the threaded hole.

[0011] Preferably, the hold-down device has a pressure element axially pre-tensioned by a spring element, wherein the pressure element exerts a load on the electrodes to be welded together. The spring-loaded pressure element is provided in the area where the electrodes to be welded are pressed together and is axially displaceable and spring-loaded.

[0012] This spring-loaded pressure element allows the electrodes to be reliably pressed together, compensating for tolerances and preventing over-pressing of the electrodes.

[0013] In a preferred embodiment, the hold-down device rests against at least one spacer provided on the end plate, thereby achieving a predefined compression of the overlapping electrodes and preventing damage to the electrodes from excessive mechanical stress exerted on them by the hold-down device, while also ensuring that the electrodes to be welded are in contact with each other.

[0014] Preferably, the welding unit is a laser welding unit, which achieves a concentrated energy input exclusively at the electrodes and prevents damage to the surrounding components of the battery cell due to high thermal stress.

[0015] The problem is further solved by a battery with the features of claim 6, wherein the battery comprises a plurality of battery cells and is manufactured using a welding device according to any one of claims 1 to 6. This allows the manufacturing costs of the battery to be reduced.

[0016] Preferably, the clamping element has a cooling channel adjacent to the welded electrodes. The electrodes of the battery cells heat up during battery operation. The cooling channel arranged on the clamping element and adjacent to the electrodes allows for active cooling of the electrodes, thereby increasing the battery's service life.

[0017] In a preferred embodiment, the battery cells are designed as pouch cells. Due to the absence of an outer casing, pouch cells are thin and lightweight, allowing the battery to be smaller and lighter.

[0018] The problem is further solved by a method for manufacturing a battery with a welding device according to one of claims 1 to 6 with the features of claim 9.

[0019] First, the clamp is attached to the end plate. Attaching the clamp presses the electrodes to be joined together between the clamp's counterpart and the clamp. The welding unit is then activated, welding the pressed electrodes together. Finally, the clamp is removed. This method reduces battery manufacturing costs because only the welding unit needs to be moved during the numerous welding operations, thus reducing the power required by the drive mechanism for moving the welding unit.

[0020] An embodiment of the invention is explained in more detail with reference to the drawing.

[0021] The figure shows a welding device according to the invention in a schematic view.

[0022] The figure depicts a battery 10, for example a traction battery for an electric vehicle, wherein the traction battery supplies electrical energy to at least one electric machine connected to a drive axle of the electric vehicle.

[0023] The battery 10 includes a plurality of battery cells 201 , 202 , 203 , 204 , 205 , 206 , 207 , 208 , which are designed as pouch cells and are stacked side by side. The battery 10 can accommodate any number of battery cells 201 , 202 , 203 , 204 , 205 , 206 , 207 , 208 exhibiting, with the different number of battery cells 201 , 202 , 203 , 204 , 205 , 206 , 207 , 208 the battery's energy capacity 10can be varied. In the present version, the battery has 10 eight battery cells 201 , 202 , 203 , 204 , 205 , 206 , 207 , 208 on.

[0024] At a first axial end of the battery cells 201 , 202 , 203 , 204 , 205 , 206 , 207 , 208 is a first end plate 30 arranged and at a second axial end of the battery cells 201 , 202 , 203 , 204 , 205 , 206 , 207 , 207 , 208 is a second end plate 60 arranged. Both end plates 30 , 60 They serve to hold the battery cells together in a stacked manner 201 , 202 , 203 , 204 , 205 , 206 , 207 , 208 . The battery cells 201 , 202 ,203 , 204 , 205 , 206 , 207 , 208 are electrically connected to each other in series. Each battery cell has this feature. 201 , 202 , 203 , 204 , 205 , 206 , 207 , 208 each a first electrode 221 , 222 , 223 , 224 , 225 , 226 , 227 , 228 and a second electrode 231 , 232 , 233 , 234 , 235 , 236 , 237 , 238 up. The first electrodes 221 , 222 , 223 , 224 , 225 , 226 , 227 , 228 are at the first axial end of the respective battery cell 201 , 202 , 203 , 204 , 205 , 206 , 207 , 208 arranged and extend through one at the first end plate 30intended passageway 341 , 342 , 343 , 344 , 345 346 , 347 , 348 The second electrodes 231 , 232 , 233 , 234 , 235 , 236 , 237 , 238 are at the second axial end of the respective battery cell 201 , 202 , 203 , 204 , 205 , 206 , 207 , 208 arranged and extend through one at the second end plate each 60 intended passageway 641 , 642 , 643 , 644 , 645 , 646 , 647 , 648 .

[0025] The second electrodes 231 , 238 the battery cells arranged at the edge 201 , 208 are electrically connected to an external circuit. The remaining second electrodes 232 , 233 , 234 ,235 , 236 , 237 the battery cells 202 , 203 , 204 , 205 , 206 , 207 are each equipped with a second electrode 232 , 233 , 234 , 235 , 236 , 237 a neighboring battery cell 202 , 203 , 204 , 205 , 206 , 207 electrically connected.

[0026] The first electrodes 221 , 222 , 223 , 224 , 225 , 226 , 227 , 228 are each equipped with a first electrode 221 , 222 , 223 , 224 , 225 , 226 , 227 , 228 a neighboring battery cell 201 , 202 , 203 , 204 , 205 , 206 , 207 , 208 electrically connected.

[0027] The electrical connections between the first electrodes 221 , 222 , 223 , 224 , 225 , 226 , 227 , 228 the neighboring battery cells 201 , 202 , 203 , 204 , 205 , 206 , 207 , 208 are via a welding device 40 The electrical connections between the second electrodes are established in the same way. 232 , 233 , 234 , 235 , 236 , 237 the neighboring battery cells 202 , 203 , 204 , 205 , 206 , 207 also via the welding device 40 manufactured.

[0028] The welding device 40 a welding unit 50 and a hold-down device 42 up. In Fig. 1 is a welding process exemplified on the first end plate 30depicted.

[0029] The hold-down 42 is due to two spacers 321 , 322 the end plate 30 and is via two screws 44 , 46 at the end plate 30 fastened, with the screws 44 , 46 through two on the hold-down 42 the intended screw holes are inserted and into the first end plate 30 are screwed in. The hold-down device 42 features a hold-down section 48 on, which with several, at the end plate 30 arranged hold-down counterparts 421 , 422 , 423 , 424 interacts. The hold-down counterparts 421 , 422 , 423 , 424 each have a cooling channel 451 , 452 , 453 , 454 on, which are used to cool the electrodes 221 , 222 , 223 , 224 , 225, 226 , 227 , 228 during battery operation 10 serve.

[0030] During the welding process, the first electrodes are 221 , 222 , 223 , 224 , 225 , 226 , 227 , 228 by mounting the hold-down device 42 between the hold-down section 48 and the hold-down counterparts 421 , 422 , 423 , 424 compressed, thereby creating the first electrodes 221 , 222 , 223 , 224 , 225 , 226 , 227 , 228 They should be pressed firmly together. This prevents the first electrodes from being over-pressed. 221 , 222 , 223 , 224 , 225 , 226 , 227 , 228 The hold-down is avoided, indicates 42 several, each with a spring element 471 , 472 , 473 , 474spring-loaded and slidably mounted pressure pieces 461 , 462 , 463 , 464 up. Then the first electrodes are inserted. 221 , 222 , 223 , 224 , 225 , 226 , 227 , 228 The adjacent battery cells are welded together. For this purpose, the clamp has a through-hole for each connection. 441 , 442 , 443 , 444 on, through which the laser beam of the welding unit 50 passes through and the electrodes 221 , 222 , 223 , 224 , 225 , 226 , 227 , 228 welded together. After welding all the first electrodes. 221 , 222 , 223 , 224 , 225 , 226 , 227 , 228 the neighboring battery cells 201 , 202 , 203 , 204 , 205 , 206 ,207 , 208 will the hold-down 42 dismantled.

[0031] The electrical connection of the second electrodes 232 , 233 , 234 , 235 , 236 , 237 This is done in the same way, with the second electrodes being welded together. 232 , 233 , 234 , 235 , 236 , 237 a corresponding hold-down device on the second end plate 60 is mounted and on the second end plate 60 corresponding hold-down counterparts 621 , 622 , 623 are planned.

[0032] Other constructive embodiments besides those described are also possible, which fall within the scope of protection of the main claim. 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] EP 3305460 A1

[0003]

Claims

[1] Welding device for welding electrodes of two adjacent battery cells of a battery, with a hold-down device (42) which is designed to press the two electrodes (221, 222, 223, 224, 225, 226, 227, 228) of the adjacent battery cells (201, 202, 203, 204, 205, 206, 207, 208) to be welded together in such a way that the overlapping electrodes (221, 222, 223, 224, 225, 226, 227, 228) are in contact with each other, and a welding unit (50) which is designed to weld together two overlapping electrodes (221, 222, 223, 224, 225, 226, 227, 228) of the adjacent battery cells (201, 202, 203, 204, 205, 206, 207, 208) pressed together by the hold-down device (42), characterized by , that The retainer (42) for welding the electrodes (221, 222, 223, 224, 225, 226, 227, 228) is detachably fastened to an end plate (30) of the battery (10) which accommodates the battery cells (201, 202, 203, 204, 205, 206, 207, 208), wherein the end plate (30) has a retainer counterpart (421, 422, 423, 424) corresponding to the retainer (42), wherein the overlapping electrodes (221, 222, 223, 224, 225, 226, 227, 228) to be welded together are pressed together between the retainer (42) and the retainer counterpart (421, 422, 423, 424) are arranged. [2] Welding device according to claim 1, characterized by, that the hold-down device (42) has a hold-down section (48) on its side facing the end plate (30), with which the hold-down device (42) bears against the overlapping electrodes (221, 222, 223, 224, 225, 226, 227, 228), wherein the welding unit (50) is arranged on a side of the hold-down device (42) facing away from the end plate (30), wherein the hold-down device (42) has a through-opening (441, 442, 443, 444) through which a welding jet of the welding unit (50) extends. [3] Welding device according to claim 1 or 2, characterized by , that the hold-down device (42) can be fastened to the end plate (30) by at least one screw (44, 46). [4] Welding device according to one of the preceding claims, characterized by, that the hold-down device (42) has a pressure element (461, 462, 463, 464) axially pre-tensioned via a spring element (471, 472, 473, 474), wherein the pressure element (461, 462, 463, 464) loads the electrodes (221, 222, 223, 224, 225, 226, 227, 228) to be welded together. [5] Welding device according to one of the preceding claims, characterized by , that the hold-down device (42) rests against at least one spacer (321, 322) provided on the end plate (30). [6] Welding device according to one of the preceding claims, characterized by that the welding unit (50) is a laser welding unit. [7] Battery comprising a plurality of battery cells and manufactured with a welding device according to any one of claims 1 to 6. [8] Battery according to claim 7, characterized by, that the hold-down counterpart (421, 422, 423, 424) has a cooling channel (451, 452, 453, 454) adjacent to the welded electrodes (221, 222, 223, 224, 225, 226, 227, 228). [9] Battery according to claim 7 or 8, characterized by , that the battery cells (201, 202, 203, 204, 205, 206, 207, 208) are designed as pouch cells. [10] Method for manufacturing a battery using a welding device according to any one of claims 1 to 6, wherein the method comprises the following steps: - Attaching the hold-down device (42) to the end plate (30), whereby by attaching the hold-down device (42) the electrodes (221, 222, 223, 224, 225, 226, 227, 228) to be connected are pressed together between the hold-down device counterpart (421, 422, 423, 424) and the hold-down device (42), - Welding of the pressed-together electrodes (221, 222, 223, 224, 225, 226, 227, 228). - Dismantling the hold-down device (42).

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