Battery cell tongue shape variations to optimize battery cell-to-busbar electrical connections

Abstract

Example battery cell terminal tab and busbar configurations are provided for electrically connecting battery cells within a traction battery pack. An example battery cell may include a terminal tab having a tab end portion shaped to provide a local thickness increase configured to reduce weld spatter and increase weld quality when the terminal tab is welded to a busbar. The busbar may include a weld butt support structure that facilitates positioning and welding the terminal tab to the busbar.

Description

FIELD OF TECHNOLOGY

[0001] This disclosure relates generally to traction battery packs of electrified vehicles and, more particularly, to techniques for electrically connecting battery cells of traction battery packs. GENERAL STATE OF THE ART

[0002] A high-voltage traction battery pack typically supplies power to the electric motors and other electrical loads of an electrified vehicle. The traction battery pack contains numerous battery cells. The battery cells must be reliably interconnected to provide the voltage and power levels necessary to achieve vehicle propulsion. SUMMARY

[0003] A battery cell according to an exemplary aspect of the present disclosure includes, among other things, a housing and a terminal tab protruding outwardly from the housing. The terminal tab includes a tab end portion having a shape that provides a local thickness increase configured to reduce weld spatter when the terminal tab is welded to a busbar.

[0004] In a further non-limiting embodiment of the above battery cell, the mold includes a crimped portion that provides the local thickness increase at the tongue end region.

[0005] In a further non-limiting embodiment of any of the above battery cells, the shape extends along a curved path that provides the local thickness increase at the tongue end region.

[0006] In a further non-limiting embodiment of any of the foregoing battery cells, the curved path establishes a convex shape of the tongue end portion.

[0007] In a further non-limiting embodiment of any of the foregoing battery cells, a first bend connects the tab end portion to a proximal tab portion of the terminal tab.

[0008] In a further non-limiting embodiment of any of the foregoing battery cells, a second bend connects a distal tip portion of the tongue end region to a proximal tip portion of the tongue end region.

[0009] In a further non-limiting embodiment of any of the foregoing battery cells, the distal tip portion is folded about the second bend toward the proximal tip portion.

[0010] In a further non-limiting embodiment of any of the foregoing battery cells, the second bend establishes a portion of a crimped portion of the tongue end region.

[0011] In a further non-limiting embodiment of any of the foregoing battery cells, a second bend positions a distal tip portion of the tongue end region at an angle relative to a proximal tip portion of the tongue end region.

[0012] In a further non-limiting embodiment of any of the foregoing battery cells, the distal tip portion extends toward and is spaced from the proximal tongue region.

[0013] A traction battery pack according to another exemplary aspect of the present disclosure includes, among other things, a bus bar including an opening and a weld butt support structure provided proximate the opening, wherein a battery cell includes a terminal tab extending into the opening to a position adjacent to the weld butt support structure and a weld securing the terminal tab to the weld butt support structure.

[0014] In another non-limiting embodiment of the above traction battery pack, the weld joint support structure includes a bent portion.

[0015] In a further non-limiting embodiment of any of the foregoing traction battery packs, the distal end portion of the terminal tab is received on an angled surface of the bent portion of the weld joint support structure.

[0016] In a further non-limiting embodiment of any of the foregoing traction battery packs, the distal end region includes a crimped portion or extends along a curved path to provide a local increase in thickness.

[0017] In a further non-limiting embodiment of any of the foregoing traction battery packs, the weld butt support structure includes a bent portion bent relative to a body of the bus bar.

[0018] In a further non-limiting embodiment of any of the foregoing traction battery packs, the distal end portion of the terminal tab is received on an angled surface of the bent portion of the weld joint support structure.

[0019] In a further non-limiting embodiment of any of the foregoing traction battery packs, the distal end region includes a crimped portion or extends along a curved path to provide a local increase in thickness.

[0020] In a further non-limiting embodiment of any of the foregoing traction battery packs, the terminal tab includes at least two bends.

[0021] In a further non-limiting embodiment of any of the foregoing traction battery packs, the bus bar includes a first metallic material and the terminal tab includes a second metallic material different from the first metallic material.

[0022] A method for establishing an electrical connection between a battery cell and a busbar according to another exemplary aspect of the present disclosure includes, among other things, positioning a terminal tab of the battery cell within an opening of the busbar and at a position adjacent to a weld butt support structure of the busbar, and welding the terminal tab to the weld butt support structure. The terminal tab includes a shape that provides a local thickness increase within a tab end region of the terminal tab to reduce weld spatter and increase weld quality during welding.

[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 schematically illustrates an electrified vehicle. Fig. 2 is a perspective view of a traction battery pack of an electrified vehicle. Fig. 3 is a highly schematic cross-sectional view of the traction battery pack of Fig. 2. Fig. Figure 4 illustrates a battery cell for use within a traction battery pack. Fig. Figure 5 illustrates selected portions of a bus bar configured to join terminal tabs of a grouping of battery cells. Fig. 6 is a cross-sectional view through section 6-6 of Fig. 5. Fig. 7 is a cross-sectional view of another exemplary bus bar for joining terminal tabs of a grouping of battery cells. Fig. 8A and Fig. 8B illustrate an example terminal tab of a battery cell. Fig. 9A and Fig. 9B illustrate another exemplary terminal tab of a battery cell. Fig. 10 illustrates another exemplary terminal tab of a battery cell. Fig. 11 illustrates another exemplary terminal tab of a battery cell. Fig. 12 illustrates another exemplary terminal tab of a battery cell. Fig. 13 illustrates yet another exemplary terminal tab of a battery cell. DETAILED DESCRIPTION

[0025] This disclosure describes in detail exemplary battery cell terminal tab and busbar configurations for electrically connecting battery cells within a traction battery pack. An exemplary battery cell may include a terminal tab having a tab end portion shaped to provide a local thickness increase configured to reduce weld spatter and increase weld quality when the terminal tab is welded to a busbar. The busbar may include a weld butt support structure that facilitates positioning and welding the terminal tab to the busbar. 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 the illustrated embodiment, the electrified vehicle 10 is an all-electric vehicle powered solely by electric power, such as one or more electric machines 12, without assistance from an internal combustion engine. The electric machine 12 may operate as an electric motor, an electric generator, or both. The electric machine 12 receives electric power and may convert the electric power into torque to drive one or more wheels 14 of the electrified vehicle 10.

[0029] 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 cells 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.

[0030] 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.

[0031] The Fig. 2 and Fig. 3 illustrate additional details associated with the traction battery pack 18 of the electrified vehicle 10. The traction battery pack 18 may include one or more battery banks 22 (e.g., battery assemblies or arrays of rechargeable battery cells 24) 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.

[0032] The battery cells 24 may be stacked side by side along a stack axis to construct a grouping of battery cells 24, sometimes referred to as a “cell stack.” In the highly schematic illustration of Fig. 3, the battery cells 24 are stacked in a plane-to-plane direction to construct each battery bank 22, and thus, the battery banks 22 may extend in a vehicle transverse direction. However, other configurations may be possible. The total numbers of battery banks 22 and battery cells 24 provided within the traction battery pack 18 are not intended to limit this disclosure.

[0033] In one embodiment, the battery cells 24 of each battery bank 22 are pouch-type lithium-ion cells. Alternatively, however, battery cells having other geometries (cylindrical, prismatic, etc.), other chemistries (nickel-metal hydride, lead-acid, etc.), or both could be utilized within the scope of this disclosure.

[0034] The battery banks 22 and various other internal battery components (e.g., an electrical distribution box with bus, an electrical battery control module, wiring, connectors, etc.) may be located within an interior compartment 26 (see Fig. 3) an enclosure assembly 28. The enclosure assembly 28 may include an enclosure cover 30 and an enclosure shell 32. The enclosure cover 30 may be attached (e.g., bolted, welded, glued, etc.) to the enclosure shell 32 to provide the interior compartment 26. The size, shape, and overall configuration of the enclosure assembly 28 are not intended to limit this disclosure.

[0035] Fig. 4 illustrates one of the battery cells 24 that may be provided within the traction battery pack 18. Each battery cell 24 may include a housing 36 and a pair of terminal tabs 34 projecting outwardly from the housing 36. In one embodiment, each battery cell 24 includes two terminal tabs 34, with one terminal tab 34 projecting outwardly on each opposite side of the housing 36. One of the terminal tabs 34 may provide the positive terminal of the battery cell 24, and the other terminal tab 34 may provide the negative terminal of the battery cell 24. However, other configurations are further contemplated within the scope of this disclosure.

[0036] The terminal tabs 34 of the battery cells 24 of each battery bank 22 must be reliably connected to each other to provide the voltage and power levels necessary to achieve vehicle propulsion. Bus bars are sometimes used to make these connections, but it can be difficult to properly position and align the terminal tabs 34 relative to the bus bar during assembly and welding processes. Furthermore, the bus bars are typically thicker than the terminal tabs 34, introducing welding complexity that can lead to weld penetration and / or weld spatter. This disclosure is therefore specifically directed to variations in the shape of terminal tabs that can be used to optimize battery cell-to-bus bar electrical connections.

[0037] Fig. 5 and Fig. 6 illustrate portions of a bus bar 38 that may be mated with terminal tabs 34 of a grouping of battery cells 24 for electrically connecting the battery cells 24. The grouping of battery cells 24 may, for example, be part of one of the battery banks 22 of the traction battery pack 18. Once electrically coupled, the battery cells 24 may supply electrical power to power various components of the electrified vehicle 10.

[0038] The terminal tabs 34 and the bus bar 38 may be metallic components. In one embodiment, the bus bar 38 is made of copper or aluminum, and the terminal tabs are made of aluminum. However, other materials or combinations of materials are contemplated within the scope of this disclosure.

[0039] The busbar 38 may include a plurality of openings 40. Each opening 40 may be formed through a body 42 of the busbar 38 and may be sized to receive one of the terminal tabs 34. Each terminal tab 34 may extend at least partially into one of the openings 40.

[0040] The busbar 38 may additionally include a plurality of weld butt support structures 44 at which the terminal tabs 34 may interface with the busbar 38. A weld butt support structure 44 may be provided at each opening 40 of the busbar 38 and could, for example, be configured to form a base of the opening 40. In one embodiment, the weld butt support structures 44 extend from the body 42 in a direction away from the battery cells 24.

[0041] In one embodiment, each weld butt support structure 44 may include a bent portion 46 formed in the body 42 of the bus bar 38. The bent portion 46 may extend in a direction away from the battery cell 24 from which the terminal tab 34 protrudes and may provide an elongated groove 50 for receiving the terminal tab 34. The bent portion 46 may limit the distance the terminal tab 34 may be inserted into the elongated groove 50. For example, an inner surface 48 of the bent portion 46 may act as a stop to limit the insertion distance of the terminal tab 34. In this way, the bent portions 46 may assist in locating and positioning the terminal tab 34 relative to the bus bar 38. Outer regions 35 (see Fig. 5) the connecting tongues 34 may extend outside the elongated grooves 50 formed by the bent portions 46.

[0042] In another embodiment, each weld butt support structure 44 may include a flared portion 52 as an alternative to the bent portion 46 (see Fig. 7). Each flared portion 52 may protrude in a direction away from the battery cells 24.

[0043] The connecting tabs 34 may be received on an angled surface 54 of the weld butt support structures 44. Each angled surface 54 may provide a relatively flat surface for creating one or more welds 56 for joining the tab end portion 60 to the angled surface 54.

[0044] Each terminal tab 34 may be joined to the angled surface 54 of one of the weld butt support structures 44 of the busbar 38 by one or more welds 56. The welds 56 may be linear welds, non-linear welds, or any other weld pattern. Prior to forming the welds 56, the terminal tabs 34 may optionally be clamped and / or tack welded to the weld butt support structures 44 to assist in the joining process.

[0045] The shape of each terminal tab 34 can be specifically designed to optimize the electrical connection between the battery cell and the busbar. A first exemplary configuration of terminal tabs 34 that can provide optimized electrical connections between the battery cell and the busbar is shown in the Fig. 8A and Fig. 8B (with continued reference to the Fig. 3-6). The exemplary terminal tab 34 may include a proximal tab portion 58 extending from in-cell electrodes to a position external to the housing 36 of the battery cell 24. The proximal tab portion 58 may be substantially straight along its length.

[0046] The connecting tongue 34 may additionally include a first bend 62 that positions a tongue end portion 60 at an angle relative to the proximal tongue portion 58. The tongue end portion 60 may include a proximal tip portion 66 and a distal tip portion 68. The distal tip portion 68 may be folded about a second bend 70 toward the proximal tip portion 66. Once folded, the distal tip portion 68 may be positioned between the proximal tip portion 66 and the proximal tongue portion 58. The distal tip portion 68 may contact the proximal tongue portion 58 or could be slightly spaced therefrom.

[0047] Together, the proximal tip portion 66, the distal tip portion 68, and the second bend 70 can create a crimped portion 72 of the tab end region 60. The crimped portion 72 provides a local thickness increase TI at the tab end region 60 of the terminal tab 34. The terminal tab 34 is thus less susceptible to weld-through and effectively limits weld spatter in a direction toward the battery cell 24 during the process of welding the tab end region 60 of the terminal tab 34 to the busbar 38.

[0048] Fig. 9A and Fig. 9B illustrate another exemplary terminal tab 134 shaped to optimize electrical connection between the battery cell and the bus bar. The exemplary terminal tab 134 may include a proximal tab portion 158 that may be connected to the housing of a battery cell. The proximal tab portion 158 may be substantially straight along its length.

[0049] The connecting tongue 134 may additionally include a first bend 162 that positions a tongue end portion 160 at an angle relative to the proximal tongue portion 158. The tongue end portion 160 may include a proximal tip portion 166 and a distal tip portion 168. A second bend 170 may position the distal tip portion 168 at an angle relative to the proximal tip portion 166. The distal tip portion 168 may extend toward the proximal tongue portion 158 and may either contact the proximal tongue portion 158 or be slightly spaced therefrom.

[0050] Due to the second bend 170, the tongue end portion 160 can extend along a curved path 174 and therefore has a convex shape. The curved path 174 forms a barrier that protects sensitive components from weld spatter. The terminal tongue 134 is thus configured to stop the momentum of weld spatter during the process of welding the tongue end portion 160 of the terminal tongue 134 to a busbar and / or to redirect weld spatter to non-hazardous areas of a battery bank / traction battery pack 24.

[0051] Fig. Figure 10 illustrates another exemplary terminal tab 234 shaped to optimize electrical connection between the battery cell and the busbar. The exemplary terminal tab 234 may include a proximal tab portion 258 that may be connected to the housing of a battery cell. The proximal tab portion 258 may be substantially straight along its length.

[0052] The connecting tongue 234 may additionally include a first bend 262 that positions a tongue end portion 260 at an angle relative to the proximal tongue portion 258 to provide a simple hook shape. The tongue end portion 260 may be substantially straight to provide a straight interface surface 261.

[0053] Fig. Figure 11 illustrates another exemplary terminal tab 334 shaped to optimize electrical connection between the battery cell and the busbar. The exemplary terminal tab 334 may include a proximal tab portion 358 that may be connected to the housing of a battery cell. The proximal tab portion 358 may be substantially straight along its length.

[0054] The connecting tab 334 may additionally include a first bend 362 that positions a tab end portion 360 at an angle relative to the proximal tab portion 358. The tab end portion 360 may extend along a curved path to provide the curved interface surface 363. The connecting tab 334 therefore provides a curved hook shape.

[0055] Fig. 12 illustrates another exemplary terminal tab 434 shaped to optimize electrical connection between a battery cell and a busbar. The exemplary terminal tab 434 may include a proximal tab portion 458 that may be connected to the housing of a battery cell. The proximal tab portion 458 may be substantially straight along its length and may further include a first bend 480.

[0056] The connecting tongue 434 may additionally include a second bend 462 that positions a tongue end portion 460 at an angle relative to the proximal tongue portion 458 to provide an alternative hook shape. The tongue end portion 460 may include a proximal tip portion 466 and a distal tip portion 468 that is in contacting contact with the proximal tip portion 466 via a third bend 482. The distal tip portion 468 may be substantially straight to provide a straight interface surface 461. The proximal tip portion 466 may also be substantially straight.

[0057] Fig.13 illustrates yet another exemplary terminal tab 534 shaped to optimize electrical connection between a battery cell and a bus bar. The exemplary terminal tab 534 may include a proximal tab portion 558 that may be connected to the housing of a battery cell. The proximal tab portion 558 may be substantially straight along its length and may further include a first bend 580.

[0058] The connecting tongue 534 may additionally include a second bend 562 that positions a tongue end portion 560 at an angle relative to the proximal tongue portion 558 to provide another alternative hook shape. The tongue end portion 560 may include a proximal tip portion 566 and a distal tip portion 568. The distal tip portion 568 may be angled relative to the proximal tip portion 566 via a third bend 582. The distal tip portion 568 may extend along a curved path to provide the curved interface surface 563.

[0059] The exemplary terminal tab shape variations described above are designed to reduce problems caused by weld penetration and weld spatter by providing a local thickness increase at the tab ends. The terminal tabs can therefore provide more consistent and accurate alignment of the terminal tab to the busbar and can further provide reduced weld defects, thereby increasing manufacturing efficiencies, reducing the need for weld repairs, and improving overall weld quality.

[0060] 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.

[0061] 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.

[0062] 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 cell, comprising: a housing; and a connecting tongue that protrudes outwards from the housing, wherein the terminal tongue includes a tongue end portion having a shape providing a local thickness increase designed to reduce weld spatter when the terminal tongue is welded to a busbar. [2] The battery cell of claim 1, wherein the shape includes a crimped edge providing the local thickness increase at the tongue end region. [3] A battery cell according to claim 1 or 2, wherein the shape extends along a closed curved path providing the local thickness increase at the tongue end region, and optionally wherein the closed curved path establishes a convex shape of the tongue end region. [4] Battery cell according to one of the preceding claims, wherein a first bend connects the tongue end region to a proximal tongue region of the connecting tongue. [5] The battery cell of claim 4, wherein a second bend connects a distal tip portion of the tongue end region to a proximal tip portion of the tongue end region. [6] The battery cell of claim 5, wherein the distal tip portion is folded around the second bend toward the proximal tip portion, and optionally wherein the second bend creates a crimped edge of the tongue end region. [7] The battery cell of claim 4, wherein a second bend positions a distal tip portion of the tongue end region at an angle relative to a proximal tip portion of the tongue end region, and optionally wherein the distal tip portion extends toward and is spaced from the proximal tongue region. [8] Traction battery pack comprising: a busbar including a slot and a welding joint support structure provided near the slot; The battery cell of claim 1, wherein the terminal tab extends into the slot to a position adjacent to the weld butt support structure; and a weld that attaches the terminal tongue to the weld joint support structure. [9] The traction battery pack of claim 8, wherein the weld butt support structure includes a crimped portion. [10] A traction battery pack according to claim 9, wherein a distal end portion of the terminal tab is received on an angled surface of the crimped portion, and optionally wherein the distal end portion includes a crimped edge or extends along a closed curved path to produce a local increase in thickness. [11] The traction battery pack according to claim 8 to 10, wherein the welding butt support structure includes a bent portion bent relative to a body of the bus bar. [12] A traction battery pack according to claim 11, wherein a distal end portion of the terminal tab is received on an angled surface of the bent portion, and optionally wherein the distal end portion includes a crimped edge or extends along a closed curved path to produce a local increase in thickness. [13] Traction battery pack according to one of claims 8 to 12, wherein the connecting tongue includes at least two bends. [14] A traction battery pack according to any one of claims 8 to 13, wherein the bus bar is made of a first metallic material and the terminal tongue is made of a second metallic material different from the first metallic material. [15] A method for establishing an electrical connection between a battery cell and a busbar, comprising: Positioning a terminal tab of the battery cell through a slot of the busbar and in a position adjacent to a weld joint support structure of the busbar; and Welding the connecting tongue to the weld joint support structure, wherein the terminal tongue includes a shape that provides a local thickness increase within a tongue end region of the terminal tongue for reducing weld spatter during welding.

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