Multi-section busbar assemblies for traction battery banks

Abstract

Battery banks for traction battery packs are provided. An exemplary battery assembly may include a multi-layer busbar assembly having at least a first busbar layer and a second busbar layer. Battery cell tab terminals may be enclosed between the first busbar layer and the second busbar layer of the busbar assembly. The battery cell tab terminals, the first busbar layer, and the second busbar layer may then be fused together, such as by one or more welds, to electrically connect a grouping of battery cells of the bank.

Description

FIELD OF TECHNOLOGY

[0001] This disclosure relates generally to traction battery packs of electrified vehicles, and more particularly to multi-piece bus bar assemblies and associated methods for electrically connecting a grouping of battery cells within a battery bank of a traction battery pack. GENERAL STATE OF THE ART

[0002] Electrified vehicles include a traction battery pack to supply power to the vehicle's electric machines and other electrical devices. The traction battery pack contains a variety of battery cells and various other internal components that support the electric vehicle's propulsion. SUMMARY

[0003] A battery bank for a traction battery pack according to an exemplary aspect of the present disclosure includes, among other things, a bus bar assembly including a first bus bar layer and a second bus bar layer, and a battery cell including a cell tab terminal sandwiched between the first bus bar layer and the second bus bar layer.

[0004] In a further non-limiting embodiment of the foregoing battery bank, the cell tab terminal extends through an opening of the first busbar layer and is bent over a first support tab of the first busbar layer.

[0005] In a further non-limiting embodiment of any of the foregoing battery banks, a second support tab of the second busbar layer is received over a portion of the cell tab terminal that is bent over the first support tab.

[0006] In a further non-limiting embodiment of any of the foregoing battery banks, a weld joins the second support tab of the second busbar layer, the cell tab terminal portion, and the first support tab of the first busbar layer.

[0007] In a further non-limiting embodiment of any of the foregoing battery banks, the welded joint is a laser welded joint.

[0008] In a further non-limiting embodiment of any of the foregoing battery banks, a second battery cell includes a second cell tab terminal sandwiched between the first busbar layer and the second busbar layer.

[0009] In a further non-limiting embodiment of any of the foregoing battery banks, the second cell tab terminal extends through a second opening of the first busbar layer and is bent over a third support tab of the first busbar layer.

[0010] In a further non-limiting embodiment of any of the foregoing battery banks, a fourth support tab of the second busbar layer is received over a portion of the second cell tab terminal that is bent over the third support tab.

[0011] In a further non-limiting embodiment of any of the foregoing battery banks, the busbar assembly is retained within a busbar module frame of a busbar module.

[0012] In a further non-limiting embodiment of any of the foregoing battery banks, the busbar module frame includes a pin received through a first mounting hole of the first busbar layer and a second mounting hole of the second busbar layer.

[0013] In a further non-limiting embodiment of any of the foregoing battery banks, the second mounting hole is keyhole-shaped.

[0014] In a further non-limiting embodiment of any of the foregoing battery banks, a configuration of the second busbar layer mimics that of the first busbar layer.

[0015] In a further non-limiting embodiment of any of the foregoing battery banks, each of the first busbar layer and the second busbar layer includes a mounting bracket.

[0016] In a further non-limiting embodiment of any of the foregoing battery banks, the cell tab terminal includes at least one bend to establish a strain relief region of the cell tab terminal.

[0017] In a further non-limiting embodiment of any of the foregoing battery banks, a weld joins the second busbar layer, the cell tab terminal, and the first busbar layer.

[0018] A method according to another exemplary aspect of the present disclosure includes, among other things, enclosing a cell tab terminal of a battery cell between a first bus bar layer and a second bus bar layer of a bus bar assembly and fusing the second bus bar layer, the cell tab terminal, and the first bus bar layer together.

[0019] In a further non-limiting embodiment of the foregoing method, sandwiching the cell tab terminal between the first busbar layer and the second busbar layer includes translating the second busbar layer in a side-to-side direction relative to the first busbar layer.

[0020] In a further non-limiting embodiment of any of the foregoing methods, the method includes bending the cell tab terminal over a support tab of the first busbar layer before or during translation of the second busbar layer relative to the first busbar layer.

[0021] In a further non-limiting embodiment of any of the foregoing methods, sliding the second busbar layer in the side-to-side direction relative to the first busbar layer includes positioning a pin of a busbar module frame into engagement with a keyhole-shaped mounting hole of the second busbar layer to lock the second busbar layer in place directly over the top of the first busbar layer.

[0022] In a further non-limiting embodiment of any of the foregoing methods, fusing the second busbar layer, the cell tab terminal, and the first busbar layer together includes welding the second busbar layer, the cell tab terminal, and the first busbar layer together.

[0023] The embodiments, examples, and alternatives of the preceding paragraphs, the claims, or the following description and drawings, including their various aspects or respective individual features, may be used independently of one another or in any combination. Features described in connection with one embodiment are applicable to all embodiments, unless such features are incompatible.

[0024] The various features and advantages of this disclosure will become apparent to those skilled in the art from the following detailed description. The drawings accompanying the detailed description may be briefly described as follows. BRIEF DESCRIPTION OF THE DRAWINGS Fig. Figure 1 shows a schematic diagram of an electrified vehicle. Fig. Figure 2 illustrates a battery bank of a traction battery pack. Fig. 3 illustrates the battery bank from Fig. 2, with portions of a bank housing removed to better illustrate a cell stack and a pair of busbar modules of the battery bank. Fig. 4 is an enlarged and exploded view of selected sections of the battery bank of Fig. 3. Fig. 5 schematically illustrates a step of a method for electrically connecting a grouping of battery cells to a busbar assembly. Fig. 6 schematically illustrates another step of a method for electrically connecting a grouping of battery cells to a busbar assembly. Fig. Figure 7 is a cross-sectional view through section 7-7 of Fig. 6. DETAILED DESCRIPTION

[0025] This disclosure describes in detail battery banks for traction battery packs. An exemplary battery assembly may include a multi-layer busbar assembly having at least a first busbar layer and a second busbar layer. Battery cell tab terminals may be enclosed between the first busbar layer and the second busbar layer of the busbar assembly. The battery cell tab terminals, the first busbar layer, and the second busbar layer may then be fused together, such as by one or more welds, to electrically connect a grouping of battery cells of the bank. These and other features are discussed in more detail in the following paragraphs of this detailed description.

[0026] Fig. 1 schematically illustrates an electrified vehicle 10. The electrified vehicle 10 may include any type of electrified powertrain. In one embodiment, the electrified vehicle 10 is a battery electric vehicle (BEV). However, the concepts described herein are not limited to BEVs and could extend to other electrified vehicles, including, but not limited to, hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), fuel cell vehicles, etc. Therefore, although not specifically illustrated in the exemplary embodiment, the powertrain of the electrified vehicle 10 could be equipped with an internal combustion engine, which can be used either alone or in combination with other power sources to propel the electrified vehicle 10.

[0027] In the illustrated embodiment, the electrified vehicle 10 is depicted as an automobile. However, the electrified vehicle 10 could alternatively be a sport utility vehicle (SUV), a van, a pickup truck, or any other vehicle configuration. Although a specific relationship of the components is illustrated in the figures of this disclosure, the illustrations are not intended to limit this disclosure. The placement and orientation of the various components of the electrified vehicle 10 are shown schematically and could vary within the scope of this disclosure. Furthermore, the various figures accompanying this disclosure are not necessarily drawn to scale, and some features may be exaggerated or minimized to highlight certain details of a particular component or system.

[0028] In one embodiment, the electrified vehicle 10 is a fully electric vehicle that is powered solely by electric power, such as one or more electric machines 12, without any assistance from an internal combustion engine.

[0029] The electric machine 12 can operate as an electric motor, an electric generator, or both. The electric machine 12 receives electrical power and can convert the electrical power into torque to drive one or more wheels 14 of the electrified vehicle 10.

[0030] A voltage bus 16 may electrically couple the electric machine 12 to a traction battery pack 18. The traction battery pack 18 is an exemplary battery of an electrified vehicle. The traction battery pack 18 may be a high-voltage traction battery pack assembly including a plurality of battery cell groupings capable of outputting electrical power to power the electric machine 12 and / or other electrical loads of the electrified vehicle 10. Alternatively or additionally, other types of energy storage devices and / or output devices could also be used to supply electrical power to the electrified vehicle 10.

[0031] The traction battery pack 18 may be attached to an underbody 20 of the electrified vehicle 10. However, the traction battery pack 18 could be located elsewhere on the electrified vehicle 10 within the scope of this disclosure.

[0032] The Fig. 2, Fig. 3 and Fig. 4 illustrate an exemplary battery bank 22 for a traction battery pack, such as the traction battery pack 18 of Fig. 1. One or more battery banks having a configuration similar to that shown in the Fig. 2-4, could be installed within an outer enclosure assembly of the traction battery pack 18.

[0033] The battery bank 22 may include a plurality of battery cells 24. In one embodiment, the battery cells 24 are lithium-ion pouch cells. However, within the scope of this disclosure, battery cells having other geometries (cylindrical, prismatic, etc.) and / or chemistries (nickel-metal hydride, lead-acid, etc.) could alternatively be used. The total number of battery cells 24 provided within the battery bank 22 could vary and thus is not intended to limit the present disclosure.

[0034] The battery cells 24 may be stacked side by side along a stack axis to create a grouping of battery cells 24. The grouping of battery cells 24 may be referred to as a cell stack 25. The cell stack 25 may be divided into two or more cell banks, although the precise configuration of the cell stack 25 is not intended to limit this disclosure.

[0035] The cell stack 25 may be arranged to extend between a pair of busbar modules 26 configured to electrically connect the battery cells 24 of the cell stack 25. For example, a busbar module 26 may be arranged along each longitudinal side of the cell stack 25.

[0036] Each busbar module 26 may include a plurality of busbar assemblies 32 held within a busbar module frame 30. Each busbar assembly 32 may be configured, for example, to electrically connect a grouping of the battery cells 24 (e.g., one of the cell banks) of the cell stack 25. The total number of busbar assemblies 32 provided as part of each busbar module 26 is not intended to limit this disclosure.

[0037] The busbar assemblies 32 may be metal components of the busbar modules 26, and the busbar module frame 30 may be a plastic component of the busbar modules 26. In one embodiment, the busbar assemblies 32 are made of copper or aluminum, and the busbar module frames 30 are made of polypropylene or polyethylene. However, other materials are contemplated within the scope of this disclosure.

[0038] The battery cells 24, the busbar modules 26 and various external internal components of the battery bank 22 can be mounted within a bank housing 28 (preferably in Fig. 2; sections of the bank housing 28 are shown in Fig. 3 removed for clarity). The bank housing 28 may be arranged to substantially surround, for example, the cell stack 25 of battery cells 24. The bank housing 28 may include a plurality of plate members 34. In one embodiment, the plate members 34 may be arranged to provide a top cover, a bottom cover, a pair of side covers, and a pair of end covers of the battery bank 22. However, the specific configuration of the bank housing 28 is not intended to limit this disclosure, and thus, other bank housing configurations are contemplated within the scope of this disclosure. Each bus bar module 26 may be positioned between the cell stack 25 and one of the plate members 34.

[0039] With reference now mainly to Fig. 3 and Fig. 4, the busbar module frame 30 of each busbar module 26 may include a plurality of slots (not shown), each sized and shaped to receive a cell tab terminal 36 of one of the battery cells 24. Each cell tab terminal 36 may protrude outwardly from a casing of its respective battery cell 24 and may extend through the busbar module frame 30 such that at least a portion of each cell tab terminal 36 is located on a side of the busbar module frame 30 opposite the respective battery cell 24.

[0040] Adjacent cell terminal tabs 36, such as those associated with one of the cell banks of the cell stack 25, may be joined together by one of the busbar assemblies 32 to electrically connect the battery cells 24 of the battery bank 22. Once electrically coupled by the busbar assemblies 32, the battery cells 24 may supply electrical power necessary to achieve electric propulsion of the electrified vehicle 10.

[0041] Each busbar assembly 32 may include a lower or first busbar layer 38 and an upper or second busbar layer 40. The first busbar layer 38 may be attached to the busbar module frame 30, and the second busbar layer 40 may be secured in place over the top of the first busbar layer 38 to create the busbar module assembly 32. In one embodiment, the configuration (e.g., size, shape, features, etc.) of the second busbar layer 40 mimics that of the first busbar layer 38.

[0042] The second busbar layer 40 may be positioned such that the cell tab terminals 36 of a grouping of the battery cells 24 of the cell stack 25 are bound or enclosed between the first busbar layer 38 and the second busbar layer 40. The first busbar layer 38, the cell tab terminals 36, and the second busbar layer 40 may then be joined together by one or more welds 42 (see Fig. 4) to electrically connect the sub-assembly of battery cells 24. In one embodiment, the welded joints 42 are laser welds formed during a laser welding process. However, other welding processes could be utilized within the scope of this disclosure.

[0043] The first busbar layer 38 and the second busbar layer 40 may each include a plurality of openings 44. In one embodiment, the openings 44 are rectangular openings, however, other shapes are contemplated within the scope of this disclosure. The openings 44 may be separated by support tabs 46. The cell tab terminals 36 may protrude through the openings 44 of the first busbar layer 38 before being bent and trapped between the support tabs 46 of the first busbar layer 38 and the second busbar layer 40. The support tabs 46 may provide relatively flat surfaces for fusing the first busbar layer 38, the cell tab terminals 36, and the second busbar layer 40 together via the welds 42.

[0044] The first busbar layer 38 and the second busbar layer 40 may each additionally include a plurality of mounting holes 48. The pins 50 of the busbar module frame 30 may be received through the corresponding mounting holes 48 of the first busbar layer 38 and the second busbar layer 40 for mounting the first busbar layer 38 and the second busbar layer 40 relative to the busbar module frame 30. The heads of the pins 50 may then be deformed, such as by hot stamping or cold forming, to secure the first busbar layer 38 and the second busbar layer 40 relative to the busbar module frame 30.

[0045] The mounting holes 48 can be round (see Fig. 4) or alternatively can have a keyhole-shaped design (see Fig. 5) to facilitate side-to-side movement and attachment of the second busbar layer 40 over the top of the first busbar layer 38.

[0046] The first busbar layer 38 and the second busbar layer 40 may each further include one or more mounting brackets 52. Fasteners (not shown) may be inserted through the mounting brackets 52 to secure the first busbar layer 38 and the second busbar layer 40 to each other and / or to the busbar module frame 30.

[0047] Fig. 5, Fig. 6 and Fig. 7 illustrate with continued reference to Fig. 3-4 schematically illustrate a method for electrically connecting a grouping G of the battery cells 24 to one of the busbar assemblies 32. The grouping G may, for example, constitute a cell bank of the cell stack 25. It should be noted that portions of the busbar module frame 30 in Fig. 5-7 are removed to better highlight various aspects of the exemplary design and method.

[0048] The first busbar layer 38 may first be arranged relative to the grouping G of battery cells 24 such that the cell tab terminals 36 extend through the openings 44 (see Fig. 5). The second busbar layer 40 can then be moved in a direction D from one side to the other from the Fig. 5 shown position to that in Fig. 6. The second busbar layer 40 could be positioned substantially over the top of the first busbar layer 38 before the second busbar layer 40 is moved from side to side in the direction D. As the second busbar layer 40 is moved from side to side in the direction D, the pins 50 of the busbar module frame 30 can engage the keyhole-shaped mounting holes 48 of the second busbar layer 40 to lock the second busbar layer 40 in place directly over the top of the first busbar layer 38 and sandwich the cell tab terminals 36 therebetween.

[0049] Movement of the second busbar layer 40 in the direction D from side to side can bend the cell tab terminals 36 into position over the support tabs 46 of the first busbar layer 38. Alternatively, the cell tab terminals 36 could be pre-bent over the support tabs 46 of the first busbar layer 38. Once the second busbar layer 40 is positioned over the top of the first busbar layer 38, the cell tab terminals 36 can be trapped between the support tabs 46 of the first busbar layer 38 and the second busbar layer 40. The first busbar layer 38, the cell tab terminals 36, and the second busbar layer 40 can then be fused together by the welds 42 to electrically connect the array G of battery cells 24.

[0050] Each cell tab terminal 36 may include one or more bends 54 (see Fig.7). The bends 54 increase the strength of the cell tab terminals 36 and provide a strain relief area to reduce the possibility of vibration problems during manufacturing.

[0051] The exemplary battery banks of this disclosure include multi-piece busbar assemblies for electrically connecting battery cells of the bank. The busbar assemblies can provide numerous advantages over known solutions, including, among other things, providing increased welding flexibility, reduced tolerance constraints, and increased current carrying capacity.

[0052] Although the various non-limiting embodiments are illustrated as having specific components or steps, the embodiments of this disclosure are not limited to these particular combinations. It is possible to use some of the components or features from any of the non-limiting embodiments in combination with features or components from any of the other non-limiting embodiments.

[0053] It should be understood that like reference numerals indicate corresponding or similar elements throughout the several views. It should be understood that while a particular component arrangement is disclosed and illustrated in these exemplary embodiments, other arrangements could also benefit from the teachings of this disclosure.

[0054] The foregoing description is intended to be interpreted as illustrative and not in a limiting sense. One of ordinary skill in the art will understand that certain modifications may be encompassed within the scope of the present disclosure. For these reasons, the following claims should be read carefully to determine the true scope and content of this disclosure.

Claims

[1] Battery bank for a traction battery pack, comprising: a busbar assembly including a first busbar layer and a second busbar layer; and a battery cell including a cell tab terminal sandwiched between the first busbar layer and the second busbar layer of the busbar assembly. [2] The battery bank of claim 1, wherein the cell tab terminal extends through an opening of the first busbar layer and is bent over a first support tab of the first busbar layer, and wherein a second support tab of the second busbar layer is received over a portion of the cell tab terminal that is bent over the first support tab. [3] The battery bank of claim 2, comprising a weld joining the second support tab of the second busbar layer, the portion of the cell tab terminal, and the first support tab of the first busbar layer, and optionally wherein the weld is a laser weld. [4] The battery bank of claim 3, comprising a second battery cell including a second cell tab terminal sandwiched between the first busbar layer and the second busbar layer. [5] The battery bank of claim 4, wherein the second cell tab terminal extends through a second opening of the first busbar layer and is bent over a third support tab of the first busbar layer, and optionally wherein a fourth support tab of the second busbar layer is received over a portion of the second cell tab terminal that is bent over the third support tab. [6] A battery bank according to any one of the preceding claims, wherein the busbar assembly is held within a busbar module frame of a busbar module. [7] The battery bank of claim 6, wherein the busbar module frame includes a pin received through a first mounting hole of the first busbar layer and a second mounting hole of the second busbar layer, and optionally wherein the second mounting hole is keyhole-shaped. [8] Battery bank according to one of the preceding claims, wherein a configuration of the second busbar layer mimics that of the first busbar layer. [9] A battery bank according to any one of the preceding claims, wherein each of the first busbar layer and the second busbar layer includes a mounting bracket. [10] Battery bank according to one of the preceding claims, wherein the cell tab terminal includes at least one bend for producing a strain relief region of the cell tab terminal. [11] A battery bank according to any one of the preceding claims, comprising a welded joint joining the second busbar layer, the cell tab terminal and the first busbar layer. [12] Method comprising: Enclosing a cell tab terminal of a battery cell between a first busbar layer and a second busbar layer of a busbar assembly; and Fusing the second busbar layer, the cell tab connection and the first busbar layer together. [13] The method of claim 12, wherein enclosing the cell tab terminal between the first busbar layer and the second busbar layer includes: Moving the second busbar layer in a side-to-side direction relative to the first busbar layer. [14] A method according to claim 13, comprising: Bending the cell tab connection over a support tab of the first busbar layer before or during the displacement of the second busbar layer relative to the first busbar layer, and optionally wherein shifting the second busbar layer in the side-to-side direction relative to the first busbar layer comprises: Positioning a pin of a busbar module frame into engagement with a keyhole-shaped mounting hole of the second busbar layer to lock the second busbar layer in place directly over the top of the first busbar layer. [15] The method of any one of claims 12 to 14, wherein fusing the second busbar layer, the cell tab terminal, and the first busbar layer together includes: Welding the second busbar layer, the cell tab connection and the first busbar layer together.

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