TRACTION BATTERY PACK THERMAL MANAGEMENT ASSEMBLY

A traction battery pack assembly includes an enclosure assembly that provides an interior area and a cell stack within the interior area. The cell stack includes battery cells disposed along a cell stack axis. A thermal management assembly is disposed along the cell stack axis. The thermal management assembly includes thermal blockers secured to a base assembly. The base assembly includes a sandwiched region and at least one projecting region. The sandwiched region is disposed along the cell stack axis and is sandwiched between first and second battery cells. The projecting region is outboard of the sandwiched region relative to the cell stack axis. The thermal blockers are secured to the at least one projecting region of the base assembly.

TECHNICAL FIELD

This disclosure relates generally to managing thermal energy within a traction battery pack.

BACKGROUND

A traction battery pack of an electrified vehicle can include groups of battery cells arranged in one or more cell stacks. From time to time, pressure and thermal energy within one or more of the battery cells can increase and cause gas and debris to vent from those battery cells.

SUMMARY

In some aspects, the techniques described herein relate to a traction battery pack assembly, including: an enclosure assembly that provides an interior area; a cell stack within the interior area, the cell stack having a plurality of battery cells disposed along a cell stack axis; and a thermal management assembly disposed along the cell stack axis, the thermal management assembly including a plurality of thermal blockers secured to a base assembly, the base assembly including a sandwiched region and at least one projecting region, the sandwiched region disposed along the cell stack axis and sandwiched between first and second battery cells, the at least one projecting region outboard of the sandwiched region relative to the cell stack axis, the plurality of thermal blockers secured to the at least one projecting region of the base assembly.

In some aspects, the techniques described herein relate to a traction battery pack assembly, wherein the plurality of battery cells include a plurality of pouch-style battery cells.

In some aspects, the techniques described herein relate to a traction battery pack assembly, wherein plurality of thermal blockers include thermal blockers secured to opposing axial sides of the at least one projecting region on a first outboard side of the cell stack.

In some aspects, the techniques described herein relate to a traction battery pack assembly, wherein the plurality of thermal blockers further includes thermal blockers secured to opposing axial sides of the at least one projecting region on an opposite, second outboard side of the cell stack.

In some aspects, the techniques described herein relate to a traction battery pack assembly, further including an adhesive that secures the plurality of thermal blockers to the at least one projecting region of the base assembly.

In some aspects, the techniques described herein relate to a traction battery pack assembly, wherein the adhesive is an adhesive tape.

In some aspects, the techniques described herein relate to a traction battery pack assembly, wherein the base assembly includes a thermal barrier, the adhesive tape include a first piece of tape on a first axial side of the thermal barrier, and a second piece of tape on an opposite, second axial side of the thermal barrier.

In some aspects, the techniques described herein relate to a traction battery pack assembly, wherein the first piece of tape secures at least one thermal blocker from the plurality of thermal blockers to the at least one projecting region on a first outboard side of the cell stack, and secures at least one other thermal blocker from the plurality of thermal blockers to the at least one projecting region on an opposite second outboard side of the cell stack.

In some aspects, the techniques described herein relate to a traction battery pack assembly wherein the base assembly is provided entirely by an adhesive tape.

In some aspects, the techniques described herein relate to a traction battery pack assembly, wherein the thermal management assembly is configured to block vent byproducts expelled from one or more battery cells on a first axial side of the thermal management assembly from moving adjacent battery cells on an opposite, second axial side of the thermal management assembly.

In some aspects, the techniques described herein relate to a traction battery pack assembly, wherein the base assembly is a first material, and the thermal blocker is a second, different material.

In some aspects, the techniques described herein relate to a traction battery pack assembly, wherein the thermal blocker is foam.

In some aspects, the techniques described herein relate to a traction battery pack assembly, wherein the base assembly includes mica.

In some aspects, the techniques described herein relate to a method of managing battery pack thermal energy, including: within an enclosure assembly, supporting thermal blockers that are disposed at opposing sides of a cell stack using a base assembly of a thermal management assembly, the base assembly at least partially sandwiched between a first and a second battery cell of the cell stack.

In some aspects, the techniques described herein relate to a method14, further including adhesively securing the thermal blockers to the base assembly.

In some aspects, the techniques described herein relate to a method15, further including securing at least some of the thermal blockers to a first axial side of the base assembly using adhesive tape.

In some aspects, the techniques described herein relate to a method16, further including securing the first battery cell to the first axial side of the base assembly using the adhesive tape.

In some aspects, the techniques described herein relate to a method17, further including securing some of the thermal blockers and the second battery cell to an opposite second side of the base assembly using adhesive tape.

In some aspects, the techniques described herein relate to a method14, wherein the base assembly is an adhesive tape.

DETAILED DESCRIPTION

This disclosure details exemplary thermal management assemblies for a traction battery pack. The thermal management assemblies can help to, among other things, secure battery cells together and help guide vent byproducts during a thermal event. The thermal management assemblies can include a plurality of thermal blockers. Thus, a separate installation of thermal blockers may not be required.

With reference toFIG.1, an electrified vehicle10includes a battery pack14, an electric machine18, and wheels22. The battery pack14powers an electric machine18, which can convert electrical power to mechanical power to drive the wheels22.

The battery pack14is, in the exemplary embodiment, secured to an underbody26of the electrified vehicle10. The battery pack14could be located elsewhere on the electrified vehicle10in other examples.

The electrified vehicle10is an all-electric vehicle. In other examples, the electrified vehicle10is a hybrid electric vehicle, which selectively drives wheels using torque provided by an internal combustion engine instead of, or in addition to, an electric machine. Generally, the electrified vehicle10could be any type of vehicle having a battery pack.

Referring toFIGS.2and3, the battery pack14includes a plurality of cell stacks30held within an interior of an enclosure assembly34. In the exemplary embodiment, the enclosure assembly34includes an enclosure cover38and an enclosure tray42. The enclosure cover38is secured to the enclosure tray42to provide an interior area44that houses the cell stacks30. The enclosure cover38can be secured to the enclosure tray42using mechanical fasteners (not shown), for example.

Each of the cell stacks30includes a plurality of battery cells50(or simply, “cells”) and a plurality of thermal management assemblies54. Within each of the cell stacks30, the cells50are arranged in groups and disposed along a cell stack axis A. The thermal management assemblies54are disposed along the cell stack axis A between groups of the cells50.

The battery cells50store and supply electrical power. Although specific numbers of the cell stacks30and cells50are illustrated in the various figures of this disclosure, the battery pack14could include any number of the cell stacks30having any number of individual cells50. The groups of battery cells50can include multiple battery cells50or only one battery cell50.

In an embodiment, the battery cells50are lithium-ion pouch-style battery cells. However, battery cells having other geometries (cylindrical, prismatic, etc.) other chemistries (nickel-metal hydride, lead-acid, etc.), or both could alternatively be utilized within the scope of this disclosure.

From time to time, pressure and thermal energy within one or more of the battery cells50can increase. The pressure and thermal energy increase can be due to an overcharge condition, for example. The pressure and thermal energy increase can cause the associated battery cell50to rupture and expel vent byproducts, such as gas and debris, from within the battery cell50. The vent byproducts can be released from the associated battery cell50through a designated vent60within the housing, such as a membrane that yields in response to increased pressure, or through a ruptured area of the associated battery cell50.

The vent byproducts can have relatively high thermal energy levels. Guiding the vent byproducts away from other battery cells50that are not venting can prevent those battery cells50from venting and the venting event cascading through the battery pack14.

The battery pack14, in these examples, includes cross-member assemblies66disposed between cell stacks30. The cross-member assemblies66include venting passageways and openings70to the venting passageways. Vent byproducts vented through the vent60of one or more of the battery cells50can move through at least one of the openings70into venting passageway. The gas and debris are communicated though the venting passageway through an enclosure vent74to an area outside the battery pack14.

The openings70, the enclosure vent74, or both can be covered by respective membranes, for example, when venting is not needed. During venting, the vent byproducts can rupture the membranes so that the vent byproducts can flow from the battery cells50, through the openings70to the venting passageway and then through the enclosure vent74. The example cross-member assemblies66extend longitudinally in a direction that is parallel to the cell stack axes A. The cross-member assemblies66and the cell stack axes A extend in a cross-vehicle direction (i.e., from a driver side to a passenger side).

The thermal management assemblies54can help to direct vent byproducts outward relative to the respective cell stack axis A into the venting passageways within the cross-member assemblies66. The thermal management assemblies54can help to block movement of vent byproducts from one group of the battery cells50to another group of the battery cells50. Thus, thermal energy associated with the vent byproducts is prevented from heating battery cells50in other groups and causing those battery cells50to vent.

With reference now toFIGS.4-9and continuing reference toFIGS.2and3, the example battery pack14includes a first type of thermal management assembly54A (FIGS.4-6) and a second type of thermal management assembly54B. The thermal management assemblies54A separate and compartmentalize groups of battery cells50. The thermal management assemblies54B are disposed between battery cells50of the groups.

The thermal management assemblies54A, include a thermal barrier80and plurality of thermal blockers84. The thermal barrier80includes a sandwiched region88and at least one projecting region92. Within the cell stack30, the sandwiched region88is sandwiched and compressed axially between the cells50, and the at least one projecting region92is disposed outboard of the sandwiched region88relative to the cell stack axis A.

In the exemplary embodiment, the thermal blockers84are secured to opposing axial sides of the projecting region92on a first outboard side of the cell stack30, and to opposing axial side of the projecting region92on an opposite, second outboard side of the cell stack30.

In this example, two projecting regions92are used to support thermal blockers84on opposite sides for of the cell stack30. In other examples, the thermal management assembly could include a single projecting region on one horizontal side of the cell stack30.

Further, in another example, the thermal barriers80could instead or additionally be supported by at least one projecting region92that is vertically above or below the cells50. Vertical and horizontal, for purposes of this disclosure, are with reference to ground and an orientation of the vehicle10during ordinary operation.

In this example, the thermal barriers80are mica-based sheets. In other examples, the thermal barriers80could be an aerogel sheets, or a sheet having some other thermally insulative material or combination of thermally insulative materials. The thermal barrier80can extend to contact the enclosure assembly34and cross-member assemblies66to effectively compartmentalize groups of the battery cells50.

An adhesive can be used to secure the thermal blockers84to the projecting regions92of the thermal barrier80. In this example, the adhesive is a piece of adhesive tape96A. The thermal management assembly54A includes a piece of double-sided adhesive tape96A on a first axial side of the thermal barrier80, and a piece of adhesive tape96A on an opposite, second axial side of the thermal barrier80. The pieces of adhesive tape96A on each axial side of the thermal barrier80span from the projecting region92on a first outboard side to the projecting region92on an opposite, second outboard side. In this example, the thermal barrier80along with the pieces of adhesive tape96A provide a base assembly for the thermal management assembly54A.

The thermal blockers84are secured to the projecting regions92of the thermal barrier80with areas of the adhesive tape96A that are located on the projecting regions92. Remaining areas of the adhesive tape96A that are within the sandwiched region88help to bond the battery cells50to the thermal barrier80. The thermal blockers84are foam in this example.

The thermal management assembly54B includes the projecting regions92and the sandwiched region88, but omits the thermal barrier80. The thermal management assembly54B includes a piece of adhesive tape96B and a plurality of the thermal blockers84secured to the adhesive tape96B in the projecting regions92. Within the sandwiched region, the piece of adhesive tape96B is used to secure one of the battery cells50in the cell stack30to an axially adjacent battery cell50in the cell stack30. The adhesive tape96B alone provides a base assembly for the example thermal management assembly54B. That is, the base assembly is provided entirely by the adhesive tape96B in the thermal management assembly54B.

After assembling the cell stacks30, the cell stacks30include thermal blockers84along opposing outboard sides of the cell stacks30. The battery cells50can include tab terminals (not shown) that extend outboard between axially adjacent thermal blockers84to connect to one or more busbar assemblies.

Features of the disclosed examples include thermal management assemblies that include a plurality of thermal blockers. This can facilitate assembly as individually placing thermal blockers within the battery pack may not be required.