Separated traction battery pack and battery pack separation method

Abstract

The invention provides a separated traction battery pack and a battery pack separation method. A traction battery pack assembly includes a housing assembly providing an interior region. At least one cell stack having a plurality of battery cell groups disposed along a cell stack axis is within the interior region. At least one cell stack includes a plurality of separators disposed along a cell stack axis. Each of the separator assemblies is axially disposed between a first battery cell pack and a second battery cell pack of the plurality of battery cell packs. A seal is associated with each of the dividers of the plurality of dividers. A seal seals an interface between the respective divider and the housing assembly. The seal may be a strip-shaped seal.

Description

Technical Field

[0001] The present disclosure generally relates to partitioning areas of a traction battery pack to facilitate ventilation of battery cells of the traction battery pack. Background Art

[0002] The traction battery pack of an electrified vehicle may include groups of battery cells arranged in one or more cell stacks. Pressure and heat energy within one or more battery cells may increase from time to time. In response, gases and debris may be released from those battery cells. Summary of the invention

[0003] In some aspects, the technology described herein relates to a traction battery pack assembly, comprising: a housing assembly providing an internal area; at least one cell stack, the at least one cell stack having a plurality of battery cell groups arranged along an axis of the cell stack; a plurality of separators, the plurality of separators being arranged along the axis of the cell stack, each of the separator assemblies within the plurality of separator assemblies being axially arranged between a first battery cell group and a second battery cell group within the plurality of battery cell groups; and a seal associated with each of the separators within the plurality of separators, the seal sealing an interface between the corresponding separator and the housing assembly.

[0004] In some aspects, the technology described herein relates to a traction battery pack assembly in which a plurality of battery cell groups each include more than one battery cell.

[0005] In some aspects, the technology described herein relates to a traction battery pack assembly wherein the seal is a bulb seal.

[0006] In some aspects, the technology described herein relates to a traction battery pack assembly in which the seal is an intumescent endothermic doped silicon material.

[0007] In some aspects, the technology described herein relates to a traction battery pack assembly in which a seal includes a groove that receives a portion of a separator.

[0008] In some aspects, the technology described herein relates to a traction battery pack assembly, wherein a seal includes a first leg and a second leg spaced apart from the first leg, the first leg and the second leg defining a groove, the first leg being sandwiched between a first battery cell group and a separator associated with the seal along the axis of the battery stack, and the second leg being sandwiched between a second battery cell group and a separator associated with the seal along the axis of the battery stack.

[0009] In some aspects, the technology described herein relates to a traction battery pack assembly in which a seal is attached to an associated separator by an interference fit.

[0010] In some aspects, the technology described herein relates to a traction battery pack assembly in which a seal is attached to a separator by an adhesive.

[0011] In some aspects, the technology described herein relates to a traction battery pack assembly wherein the housing assembly includes a housing cover, wherein a seal associated with each of the dividers seals an interface between the dividers and an underside of the housing cover.

[0012] In some aspects, the technology described herein relates to a traction battery pack assembly in which each divider within a plurality of dividers separates a first group of battery cells from a second group of battery cells.

[0013] In some aspects, the technology described herein relates to a traction battery pack assembly in which a seal is attached to at least a vertical upper side of a separator.

[0014] In some aspects, the technology described herein relates to a traction battery pack assembly in which a seal is attached to a vertical upper side of a separator and is additionally attached to a laterally facing side of the separator.

[0015] In some aspects, the technology described herein relates to a traction battery pack assembly in which a seal is configured to block ventilation byproducts exhausted from a first group of battery cells from moving adjacent to a second group of battery cells.

[0016] In some aspects, the technology described herein relates to a traction battery pack assembly in which a seal is compressed by a housing.

[0017] In some aspects, the technology described herein relates to a method for partitioning a battery pack, the method comprising: within a housing assembly, compressing a seal between a portion of the housing assembly and a partition within a battery cell stack to block ventilation byproducts exhausted from at least one first battery cell group within the battery cell stack from flowing adjacent to at least one second battery cell group within the battery cell stack, the seal being fixed to the partition.

[0018] In some aspects, the technology described herein relates to a method in which a separator is disposed between at least one first battery cell group and at least one second battery cell group along a stack axis of a battery stack.

[0019] In some aspects, the technology described herein relates to a method in which the seal is a light bar seal.

[0020] In some aspects, the technology described herein relates to a method that also includes clamping a first leg of a seal between a first side of a separator and a first battery cell group along an axis of the battery cell stack, and clamping a second leg of the seal between an opposite second side of the separator and a second battery cell group along the axis.

[0021] In some aspects, the technology described herein relates to a method in which a seal includes a groove that receives a portion of a barrier.

[0022] The embodiments, examples and alternatives of the preceding paragraphs, claims or the following description and drawings, including any of their various aspects or respective individual features, may be taken 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

[0023] According to the detailed description, various features and advantages of the disclosed examples will become apparent to those skilled in the art. The drawings attached to the detailed description can be briefly described as follows:

[0024] Figure 1 A side view of an example electrified vehicle is shown.

[0025] Figure 2 Shown from Figure 1 An expanded perspective view of a battery pack of an electric vehicle is provided, and a cell stack of the battery pack is schematically shown.

[0026] Figure 3 Shown in Figure 2 A cross-sectional view taken at line 3-3 in FIG.

[0027] Figure 3A Shows Figure 3 Close-up of the area.

[0028] Figure 4 Shown is the installation for Figure 2 A perspective view of a portion of a seal on a portion of a separator in a battery pack. DETAILED DESCRIPTION

[0029] The present disclosure details an exemplary method and system for partitioning an internal area of ​​a traction battery pack. The partitioning can help contain and direct gases and debris exhausted from one or more battery cells during a thermal event. Directing the exhausted gases and debris away from other battery cells (other battery cells that are not ventilated) can help prevent the thermal event from cascading to those other battery cells.

[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 the electric power into mechanical energy 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 Figures 2 to 4 , the battery pack 14 includes a plurality of cell stacks 30 held within an interior of a housing assembly 34. In an exemplary embodiment, the housing assembly 34 includes a housing cover 38 and a housing tray 42. The housing cover 38 is secured to the housing tray 42 to provide an interior area 44 for housing the cell stacks 30. The housing cover 38 may be secured to the housing tray 42 using, for example, mechanical fasteners (not shown).

[0034] Each of the cell stacks 30 includes a plurality of battery cells 50 (or simply “cells”) and a plurality of separators 54 disposed along a respective cell stack axis A. The cell stacks 30 each extend from a first axial end 56A to an opposite second axial end 56B.

[0035] Within each cell stack 30, battery cells 50 are stacked side by side relative to each other along a cell stack axis A. The battery cells 50 are arranged in groups that are separated from each other along the axis A by one of the separators 54. In this example, the separator 54 is a mica sheet. In other examples, the separator 54 may be an aerogel sheet or a sheet having some other insulating material or combination of insulating materials.

[0036] The battery cells 50 store and supply power. Although a specific number of cell stacks 30 and cells 50 are shown in various figures of the present disclosure, the battery pack 14 can include any number of cell stacks 30 having any number of individual cells 50. In this example, the battery cell groups 50 each include four battery cells. In other examples, the battery cell groups 50 include more than four battery cells or less than four battery cells. In some examples, the battery cell group 50 may include one battery cell.

[0037] 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 also be used within the scope of the present disclosure.

[0038] Sometimes, pressure and heat energy may increase within one or more of the battery cells 50. For example, the increase in pressure and heat energy may be caused by an overcharge condition. The increase in pressure and heat energy may cause the associated battery cell 50 to rupture and expel ventilation byproducts, such as gases and debris, from the battery cell 50.

[0039] The venting byproducts may be released from the associated battery cell 50 through a designated vent 60 within the housing (such as a membrane that yields in response to the pressure increase) or through a ruptured area of ​​the associated battery cell 50 .

[0040] In these examples, the battery pack 14 includes a cross member assembly 66 disposed between the battery stacks 30. The example cross member assembly 66 extends longitudinally in a direction parallel to the battery stack axis A. The cross member assembly 66 and the battery stack axis A extend in a vehicle lateral direction (i.e., from the driver side to the passenger side).

[0041] In this example, the cross member assembly 66 includes a ventilation passage and an opening 70 leading to the ventilation passage. Ventilation byproducts exhausted through the vents 60 of one or more of the battery cells 50 can move through at least one of the openings 70 into the ventilation passage. Gases and debris are transported through the ventilation passage through the housing vents 74 to areas outside the battery pack 14. For example, when ventilation is not required, the openings 70, the housing vents 74, or both can be covered by corresponding membranes. During ventilation, the ventilation byproducts can rupture the membrane so that the ventilation byproducts can flow from the battery 50 through the openings 70 to the ventilation passage and then through the housing vents 74.

[0042] To help direct gas and debris outwardly about the cell stack axis A through the opening 70 rather than along an axis adjacent to the other battery cells 50, a seal 78 is secured to each of the dividers 54. When the battery pack 14 is assembled, the seal 78 is compressed between the housing assembly 34 (here, the underside 80 of the housing cover 38) and the vertical upper side of the divider 54. For purposes of this disclosure, vertical and horizontal are referenced to the ground and the orientation of the vehicle 10 during normal operation.

[0043] The seal 78 seals the interface between the respective divider 54 and the housing assembly 34. This prevents ventilation byproducts from moving along the cell stack axis A from the battery cells 50 on one side of the divider 54 to the battery cells 50 on the opposing second side of the divider 54. The ventilation byproducts are instead directed outwardly away from the cell stack axis A into the opening 70 in the cross member assembly 66.

[0044] In this example, the seal 78 is a light bar seal. The seal 78 may be an expandable heat absorbing doped silicon material.

[0045] The seal 78 includes a groove 82 defined between a first leg 86 spaced apart from a second leg 90. When installed on the divider 54, the groove 82 receives a portion of the divider 54. The seal 78 can be secured to the respective divider 54 by an interference fit. In another example, an adhesive can alternatively or additionally be used to secure the seal 78 to the respective divider 54.

[0046] When the separator 54 and seal 78 are positioned within the stack 30 , the first leg 86 is sandwiched between the first group of battery cells 50 and the separator 54 along the stack axis A. The second leg 90 is sandwiched between the second group of battery cells 50 and the separator 54 along the stack axis A.

[0047] In this example, the seal 78 is attached to the vertical upper side 94 of the respective divider 54. In another example, the seal 78 may additionally be attached to the laterally facing side 98 of the divider 54.

[0048] Due to the seal 78, when one or more of the battery cells 50 are ventilated, the ventilation byproducts V contact the seal 78 and are redirected such that the ventilation byproducts V flow through the openings 70 in the cross member assembly 66 rather than flowing adjacent to other battery cells 50 in the cell stack 30. The ventilation byproducts V flowing adjacent to other battery cells 50 may increase the thermal energy levels in those battery cells 50 and result in a cascading thermal event.

[0049] In this example, the separator 54 and seal 78 separate the group of four battery cells 50 within a given one of the battery stacks 30 from the other groups of four battery cells 50 within the battery stack 30. Thus, the ventilation products V from the ventilated battery cell 50 flow adjacent to at most three other battery cells 50 within the group before moving through the opening 70.

[0050] In this example, seal 78 is compressed when housing cover 38 is secured to housing tray 42. Even if pressure associated with a venting event causes housing cover 38 to move slightly away from housing tray 42, seal 78 can decompress and remain in contact with the underside of housing cover 38 to maintain separation.

[0051] In one example, the first leg 86 and the second leg 90 are about 3.5 mm long and about 1.5 mm thick. The spacing between the groove 82 or the first leg 86 and the second leg 90 is about 4.4 mm.

[0052] The foregoing description is illustrative rather than restrictive in nature. Changes and modifications to the disclosed examples may become apparent to those skilled in the art, and the changes and modifications do not necessarily depart from the essence of the present disclosure. Therefore, the scope of protection granted to the present disclosure can only be determined by studying the attached claims.

Claims

1. A traction battery pack assembly, comprising: a housing assembly providing an interior region; at least one battery cell stack within the interior region, the at least one battery cell stack having a plurality of battery cell groups arranged along a battery cell stack axis; a plurality of separators disposed along the battery cell stack axis, each of the separator assemblies within the plurality of separator assemblies being axially disposed between a first battery cell group and a second battery cell group within the plurality of battery cell groups; as well as A seal is associated with each of the dividers within the plurality of dividers, the seal sealing an interface between the respective divider and the housing assembly.

2. The traction battery pack assembly of claim 1, wherein each of the plurality of battery cell groups includes more than one battery cell.

3. The traction battery pack assembly of claim 1, wherein the seal is a light bar seal.

4. The traction battery pack assembly of claim 1, wherein the seal is an expandable endothermic doped silicon material.

5. The traction battery pack assembly of claim 1 , wherein the seal includes a groove that receives a portion of the separator, and optionally, wherein the seal includes a first leg and a second leg spaced apart from the first leg, the first leg and the second leg defining the groove, the first leg being sandwiched along the cell stack axis between the first battery cell group and the separator associated with the seal, and the second leg being sandwiched along the cell stack axis between the second battery cell group and the separator associated with the seal.

6. The traction battery pack assembly of claim 1 wherein the seal is attached to the associated separator by an interference fit and an adhesive or both.

7. The traction battery pack assembly of claim 1, wherein the housing assembly includes a housing cover, wherein the seal associated with each of the dividers seals an interface between the dividers and an underside of the housing cover.

8. The traction battery pack assembly of claim 1, wherein each divider within said plurality of dividers separates said first group of battery cells from said second group of battery cells.

9. The traction battery pack assembly of claim 1 , wherein the seal is attached to at least the vertical upper side of the separator, and optionally wherein the seal is attached to the vertical upper side of the separator and additionally to the laterally facing sides of the separator.

10. The traction battery pack assembly of claim 1, wherein the seal is configured to block ventilation byproducts exhausted from the first group of battery cells from moving adjacent to the second group of battery cells.

11. The traction battery pack assembly of claim 1 wherein said seal is compressed by said housing.

12. A method for separating a battery pack, comprising: Within the housing assembly, a seal is compressed between a portion of the housing assembly and a separator within the battery stack to block ventilation byproducts exhausted from at least one first battery cell group within the battery stack from flowing adjacent to at least one second battery cell group within the battery stack.

13. The method of claim 12, wherein the separator is disposed between the at least one first battery cell group and the at least one second battery cell group along a stack axis of the battery stack.

14. The method of claim 12 further comprises clamping a first leg of the seal between a first side of the separator and the first battery cell group along the axis of the battery cell stack, and clamping a second leg of the seal between an opposite second side of the separator and the second battery cell group along the axis.

15. The method of claim 12, wherein the seal includes a groove that receives a portion of the divider.

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