Traction battery pack assembling method

Abstract

The invention provides a traction battery pack assembling method. A method of assembling a traction battery includes: holding a plurality of battery cells; positioning at least one gasket alongside the plurality of battery cells; and clamping at least one gasket between the plurality of battery cells and the heat exchange plate. The at least one gasket maintains a space between the heat exchange plate and the plurality of battery cells. The method further includes bonding the heat exchange plate to the plurality of battery cells using a thermal interface material.

Description

Technical Field

[0001] The present disclosure relates generally to electrified vehicle traction battery packs, and more particularly, to assembling battery packs. Background Art

[0002] A traction battery pack for an electrified vehicle may include multiple groups of battery cells arranged in one or more battery arrays. A housing may contain the battery arrays. The battery cells may swell over time. Summary of the invention

[0003] In some aspects, the technology described herein relates to a method of assembling a traction battery, the method comprising: holding a plurality of battery cells; positioning at least one spacer next to the plurality of battery cells; sandwiching the at least one spacer between the plurality of battery cells and a heat exchange plate, the at least one spacer maintaining a space between the heat exchange plate and the plurality of battery cells; and bonding the heat exchange plate to the plurality of battery cells using a thermal interface material.

[0004] In some aspects, the technology described herein relates to a method in which at least one gasket directly contacts a plurality of battery cells and a heat exchange plate after bonding.

[0005] In some aspects, the technology described herein relates to a method that also includes securing at least one spacer to a plurality of battery cells using an adhesive.

[0006] In some aspects, the technology described herein relates to a method that also includes depositing a thermal interface material on the plurality of battery cells before sandwiching at least one gasket between the heat exchange plate and the plurality of battery cells.

[0007] In some aspects, the technology described herein relates to a method that also includes retaining a plurality of battery cells within a fixture.

[0008] In some aspects, the technology described herein relates to a method in which each battery cell within a plurality of battery cells is spaced a distance from other battery cells within the plurality of battery cells to provide a gap between each of the battery cells within the plurality of battery cells.

[0009] In some aspects, the technology described herein relates to a method in which at least one shim spans a gap.

[0010] In some aspects, the technology described herein relates to a method wherein each battery cell within a plurality of battery cells includes a terminal side and a bottom side opposite the terminal side, and a gasket and a thermal interface material are directly interfaced with the bottom side of the battery cell within the plurality of battery cells.

[0011] In some aspects, the technology described herein is directed to a method in which the terminal side faces vertically downward at least during positioning and clamping.

[0012] In some aspects, the technology described herein is directed to a method that also includes securing a terminal side of a battery cell to a bus bar module.

[0013] In some aspects, the technology described herein relates to a method that also includes rotating a plurality of battery cells together with a bus bar module, at least one gasket, and a heat exchange plate, and after the rotating, inserting the plurality of battery cells, the bus bar module, and the heat exchange plate into a housing structure.

[0014] In some aspects, the technology described herein relates to a method in which the terminal side faces vertically upward after rotation.

[0015] In some aspects, the technology described herein relates to a method that also includes bonding the plurality of battery cells to constrain expansion prior to insertion.

[0016] In some aspects, the technology described herein relates to a method in which bonding includes wrapping a tension band around at least a portion of a plurality of battery cells.

[0017] In some aspects, the technology described herein relates to a traction battery assembly, the traction battery assembly comprising: a plurality of battery cells arranged along an axis, each of the battery cells within the plurality of battery cells being spaced apart a distance from other battery cells within the plurality of battery cells to provide a gap between each of the battery cells within the plurality of battery cells; a heat exchange plate; a thermal interface material that couples the plurality of battery cells to the heat exchange plate; and at least one gasket interposed between the heat exchange plate and the plurality of battery cells, the at least one gasket being configured to maintain a space between the heat exchange plate and the plurality of battery cells.

[0018] In some aspects, the technology described herein relates to an assembly in which at least one gasket is nylon.

[0019] In some aspects, the technology described herein relates to an assembly that also includes an adhesive that secures at least one spacer to the plurality of battery cells.

[0020] In some aspects, the technology described herein relates to an assembly in which at least one spacer spans a gap between each of the battery cells within a plurality of battery cells.

[0021] In some aspects, the technology described herein is directed to an assembly that also includes a bus bar module secured to the plurality of battery cells on a side of the plurality of battery cells opposite the heat exchange plate.

[0022] In some aspects, the technology described herein relates to an assembly that also includes at least one tension band extending alongside the plurality of battery cells, the at least one tension band constraining expansion of the plurality of battery cells.

[0023] The embodiments, examples and alternatives of the preceding paragraphs, claims or the following description and drawings (including any of their various aspects or corresponding individual features) may be adopted independently or in any combination. Features described in conjunction with one embodiment apply to all embodiments, unless such features are incompatible. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The various features and advantages of the present disclosure will become apparent to those skilled in the art from the following detailed description.The drawings that accompany the detailed description can be briefly described as follows.

[0025] Figure 1 An electrified vehicle is schematically shown.

[0026] Figure 2 Is from Figure 1 Partially expanded and partially cross-sectional views of a battery pack for an electrified vehicle.

[0027] Figure 3 Is from Figure 2 A close up view of an example battery cell of a battery pack 14 is shown.

[0028] Figures 4 to 15 Shows the assembly Figure 2 Steps in an exemplary method of a traction battery, wherein elements are simplified for clarity. DETAILED DESCRIPTION

[0029] The present disclosure details an exemplary traction battery pack design for use in an electrified vehicle. An exemplary traction battery pack may include a housing assembly that establishes an interior, and at least one battery array housed within the interior. These and other features are discussed in more detail in the following paragraphs of this detailed description.

[0030] refer to Figure 1 The electric vehicle 10 includes a battery pack 14, an electric motor 18, and wheels 22. The battery pack 14 supplies power to the electric motor 18, which can convert electricity into mechanical power to drive the wheels 22.

[0031] In the exemplary embodiment, the battery pack 14 is secured to an underbody 26 of the electrified vehicle 10. In other examples, the battery pack 14 may be located elsewhere on the electrified vehicle 10.

[0032] The electrified vehicle 10 is a pure electric vehicle. In other examples, the electrified vehicle 10 is a hybrid electric vehicle that selectively uses torque provided by an internal combustion engine (as an alternative or supplement to an electric machine) to drive wheels. In general, the electrified vehicle 10 can be any type of vehicle having a battery pack.

[0033] Reference now Figure 2 and Figure 3 , the battery pack 14 includes a plurality of battery arrays 30 held within a housing assembly 34. In the exemplary embodiment, the housing assembly 34 includes a housing cover 38 and a housing tray 42. The housing cover 38 can be secured to the housing tray 42 to provide an interior area 44 housing the arrays 30. The housing cover 38 can be secured to the housing tray 42 using, for example, mechanical fasteners (not shown).

[0034] Each of the battery arrays 30 includes, among other things, a plurality of battery cells 50 (or simply “cells”) arranged side by side relative to one another along a respective battery array axis A. In this example, the axes A of the battery arrays 30 are parallel relative to one another and extend longitudinally in the vehicle transverse direction.

[0035] The battery cells 50 store and supply power. Although a specific number of battery arrays 30 and cells 50 are shown in various figures of the present disclosure, the battery pack 14 may include any number of battery arrays 30 , each having any number of individual cells 50 .

[0036] In one embodiment, the battery cell 50 is a lithium-ion pouch cell. However, battery cells having other geometries (cylindrical, prismatic, etc.), other chemistries (nickel-metal hydride, lead acid, etc.), or both may alternatively be used within the scope of the present disclosure.

[0037] It is worth noting that the battery cells 50 are spaced apart from each other by a distance such that there are gaps 54 between the cells 50. The gaps 54 provide room for the battery cells 50 to expand slightly when the battery pack 14 is used in the vehicle 10. The gaps 54 may be 2.0 mm to 3.0 mm.

[0038] Each of the example battery cells 50 includes a pair of terminals 58 extending from a side 62 of an outer cover 64, which is metal in this example. The side 62 including the terminals can be considered a terminal side. In this example, when installed in the battery pack 14, the side 62 faces vertically upward. For purposes of this disclosure, vertical is referenced to the ground and the typical orientation of the vehicle 10 during operation.

[0039] Within each of the battery arrays 30 , the individual battery cells 50 may be electrically connected together. To establish these electrical connections, the terminals 58 of the example battery cells 50 are electrically connected to the bus bar modules 66 .

[0040] The battery cells 50 within each of the arrays 30 are disposed atop heat exchange plates 70. The heat exchange plates 70 may be used to manage thermal energy within the cells 50 and surrounding areas of the battery pack 14. In one example, a coolant may be circulated through the heat exchange plates 70 to absorb thermal energy from the cells 50 and cool the cells 50 during operation.

[0041] At the axial ends of the array 30 are end plates 74, which in some examples are considered to be "megabars." At least one tension band 78 extends along opposite sides of the array 30 and joins the end plates 74 together. In this example, the tension band 78 is wrapped around the array 30 to help maintain the axial position of the end plates 74, while helping to constrain the expansion of the cells and concentrate the expansion of the cells 50 into the gaps 54, rather than along the axis A into the housing tray 42. In this example, the end plates 74 are each associated with a single one of the arrays 30. In another example, the end plates 74 may span two or more of the arrays 30.

[0042] Now refer to Figures 4 to 15 1 and 2 to describe an exemplary method of assembling one of the arrays 30. For clarity, the array 30 is represented by three of the battery cells 50. Figure 2 As shown, the array 30 may include more battery cells 50 .

[0043] When assembling the array 30, each cell 50 is placed on a fixture 82, such as Figures 4 to 6 The fixture 82 includes features 86 , here ribs, that help align the individual cells 50 relative to each other to provide the desired gaps 54 between the cells 50 .

[0044] Notably, the cell 50 is placed on the fixture 82 so that the side 62 faces vertically downward and the bottom side 90 of the cell 50 faces vertically upward. In this position, the cell 50 is 180° offset from how the battery cell 50 will ultimately be arranged within the assembled battery pack 14.

[0045] refer to Figure 7 After the battery cell 50 is arranged on the fixture 82 , a block of adhesive 94 is deposited on the bottom side 90 of the battery cell 50 .

[0046] Next, if Figure 8As shown, adhesive 94 is used to secure gasket 100 to bottom side 90. Gasket 100 spans gap 54 between battery cells 50. Gasket 100 directly contacts bottom side 90 of battery cell 50. At this stage of assembly, gasket 100 can help maintain the spacing between battery cells 50, and therefore maintain gap 54. Gasket 100 can be non-metallic and fairly rigid. In some examples, gasket 100 is a nylon material strip. In some examples, the gasket can be 0.5 mm thick.

[0047] like Fig. 9 As shown, a thermal interface material (TIM) 104 is then deposited on the bottom side 90 of the battery cell 50. In this example, the TIM 104 is deposited between the spacers 100.

[0048] refer to Fig.10 The heat exchange plate 70 is then positioned on the battery cell 50 before the TIM 104 has cured. The heat exchange plate 70 is positioned so that the TIM 104 sandwiches the gasket 100 between the bottom side 90 of the battery cell 50 and the heat exchange plate 70.

[0049] The spacer 100 maintains a space S between the heat exchange plate 70 and the bottom side 90 of the battery cell 50. In this example, the space is 0.5 mm because the spacer 100 is 0.5 mm thick. Maintaining the space S provides room for the TIM 104 to cure without being squeezed out from between the heat exchange plate 70 and the battery cell 50. This ensures that enough TIM 104 is retained for bonding and ultimate heat transfer within the battery pack 14. After the TIM 104 cures, the TIM 104 fills the area between the heat exchange plate 70 and the battery cell 50 and bonds the heat exchange plate 70 to the bottom side 90 of the battery cell 50. The TIM 104 can help electrically isolate areas of the battery pack 14.

[0050] Next, refer to Fig.11 , the fixture 82 is removed, and the battery cell 50 is positioned on the bus bar module 66 so that the bus bar module 66 is opposite to the heat exchange plate 70. The bonding between the battery cell 50 and the heat exchange plate 70 and the bonding between the battery cell 50 and the gasket 100 can maintain the position of the battery cell 50 during this step. After positioning the bus bar module 66, the terminal 58 of the battery cell 50 is electrically connected to the bus bar module 66.

[0051] Then the battery cell 50 together with the bus bar module 66, the gasket 100 and the heat exchange plate 70 are rotated 180 degrees to Fig.12 This flips the battery cell 50 so that the side 62 faces vertically upward and the bottom side 90 faces vertically downward.

[0052] The end plate 74 is then positioned against the battery cell 50, as shown. Fig.13 Next, Fig.14As shown, the tension bands 114 are attached to the end panels 74. At this point, the array 30 is assembled. The array 30 can then be positioned within the housing tray 42, as shown. Fig.15 shown.

[0053] Figures 4 to 15 The example array 30 in FIG. 5 is represented by three battery cells 50 , but as previously described, the array 50 may include several more battery cells 30 .

[0054] Although different non-limiting embodiments are shown as having specific components or steps, the embodiments of the present disclosure are not limited to these specific combinations. Some components or features from any of the non-limiting embodiments may be used in combination with features or components from any of the other non-limiting embodiments.

[0055] It should be understood that like reference numerals identify corresponding or similar elements throughout the several drawings.It should be understood that although particular component arrangements are disclosed and shown in these exemplary embodiments, other arrangements may also benefit from the teachings of the present disclosure.

[0056] The foregoing description should be interpreted as illustrative and not in any limiting sense. It will be appreciated by those skilled in the art that certain modifications may occur within the scope of the present disclosure. For these reasons, the attached claims should be studied to determine the true scope and content of the present disclosure.

Claims

1. A method of assembling a traction battery, comprising: Maintain multiple battery cells; positioning at least one spacer adjacent to the plurality of battery cells; sandwiching the at least one gasket between the plurality of battery cells and the heat exchange plate, the at least one gasket maintaining a space between the heat exchange plate and the plurality of battery cells; as well as A thermal interface material is used to bond the heat exchange plate to the plurality of battery cells. 2 . The method of claim 1 , wherein the at least one gasket directly contacts the plurality of battery cells and the heat exchange plate after the bonding. 3 . The method of claim 1 , further comprising securing the at least one spacer to the plurality of battery cells using an adhesive.

4. The method of claim 1, further comprising depositing the thermal interface material on the plurality of battery cells prior to sandwiching the at least one gasket between the heat exchange plate and the plurality of battery cells.

5. The method of claim 1, further comprising retaining the plurality of battery cells in a fixture.

6. The method of claim 1 , wherein each battery cell within the plurality of battery cells is spaced apart a distance from other battery cells within the plurality of battery cells to provide a gap between each of the battery cells within the plurality of battery cells, and optionally, wherein the at least one spacer spans the gap.

7. The method of claim 1 , wherein each battery cell within the plurality of battery cells comprises a terminal side and a bottom side opposite the terminal side, the gasket and the thermal interface material directly interface with the bottom side of the battery cell within the plurality of battery cells, and optionally, wherein the terminal side faces vertically downward at least during the positioning and the clamping.

8. The method of claim 7, further comprising fixing the terminal side of the battery cell to a bus bar module, and optionally, further comprising rotating the plurality of battery cells together with the bus bar module, the at least one gasket and the heat exchange plate, and after the rotation, inserting the plurality of battery cells, the bus bar module and the heat exchange plate into a housing structure.

9. The method of claim 8, wherein after said rotating, said terminal side faces vertically upward.

10. The method of claim 8, further comprising bonding the plurality of battery cells to restrict expansion prior to said inserting, and optionally wherein said bonding comprises wrapping a tension band around at least a portion of said plurality of battery cells.

11. A traction battery assembly, comprising: a plurality of battery cells disposed along an axis, each of the battery cells within the plurality of battery cells being spaced apart a distance from other battery cells within the plurality of battery cells to provide a gap between each of the battery cells within the plurality of battery cells; Heat exchange plates; a thermal interface material that bonds the plurality of battery cells to the heat exchange plate; as well as At least one gasket is interposed between the heat exchange plate and the plurality of battery cells, the at least one gasket being configured to maintain a space between the heat exchange plate and the plurality of battery cells.

12. The assembly of claim 11 wherein said at least one spacer is nylon.

13. The assembly of claim 11 further comprising an adhesive securing the at least one spacer to the plurality of battery cells.

14. The assembly of claim 11, wherein the at least one spacer spans the gap between each of the battery cells within the plurality of battery cells.

15. The assembly of claim 11 further comprising at least one tension band extending alongside the plurality of battery cells, the at least one tension band restraining expansion of the plurality of battery cells, and optionally, further comprising a bus bar module secured to the plurality of battery cells on a side of the plurality of battery cells opposite the heat exchange plate.

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