BATTERY ARRAY THERMAL BARRIER WITH DEFLECTOR HOODS

Abstract

A battery pack assembly includes a cell stack containing a multitude of battery cells, a thermal barrier adjacent to the cell stack, and deflector hoods enclosed within the thermal barrier. Each deflector hood is configured to move from a closed to an open position in response to a flow of venting byproducts at the deflector hood.

Description

FIELD OF TECHNOLOGY

[0001] This disclosure generally relates to a thermal barrier that can direct venting byproducts from a battery cell within a battery array of a battery pack. GENERAL STATE OF THE ART

[0002] A battery pack of an electrified vehicle may contain groups of battery cells arranged in one or more battery arrays. From time to time, the pressure in one of the battery cells may increase and then be released through a vent in that battery cell. SUMMARY

[0003] In some aspects, the techniques described in this document relate to a battery pack assembly including: a cell stack having a plurality of battery cells; a thermal barrier adjacent to the cell stack; and a plurality of deflector hoods included within the thermal barrier, each deflector hood configured to move from a closed position to an open position in response to a flow of vent byproducts at the deflector hood.

[0004] In some aspects, the techniques described in this document relate to a battery pack assembly, wherein each deflector shroud has a bottom surface facing the plurality of battery cells, wherein the flow of vent byproducts contacts the bottom surface to move the deflector shroud from the closed position to the open position.

[0005] In some aspects, the techniques described in this document relate to a battery pack assembly wherein the deflector shroud, in the closed position, covers an aperture in the thermal barrier, and the deflector shroud, in the open position, allows some flow through the aperture while partially covering the aperture such that a flow of the vent byproducts through the opening contacts a bottom surface of the deflector shroud and is redirected from flows in a first direction to flows in a second direction different from the first direction.

[0006] In some aspects, the techniques described in this document relate to a battery pack assembly wherein the open position is a fully open position.

[0007] In some aspects, the techniques described in this document relate to a battery pack assembly, wherein the thermal barrier includes a plurality of notched regions, each notched region forming one of the deflector hoods within the plurality of deflector hoods.

[0008] In some aspects, the techniques described in this document relate to a battery pack assembly, wherein each notched region within the plurality of notched regions is arcuate.

[0009] In some aspects, the techniques described in this document relate to a battery pack assembly, wherein the thermal barrier includes a plurality of notches, each notch forming one of the deflector hoods within the plurality of deflector hoods.

[0010] In some aspects, the techniques described in this document relate to a battery pack assembly, wherein each notch within the plurality of notches has a C-shaped profile.

[0011] In some aspects, the techniques described in this document relate to a battery pack assembly, wherein each deflector hood within the plurality of deflector hoods is hood-shaped.

[0012] In some aspects, the techniques described in this document relate to a battery pack assembly wherein the thermal barrier is mica-based.

[0013] In some aspects, the techniques described herein relate to a battery pack assembly, wherein the plurality of battery cells are arranged along a cell stack axis, the thermal barrier is adjacent to an exterior surface of the cell stack, and the deflector shroud is configured to direct current traveling away from the cell stack axis to travel along the cell stack axis.

[0014] In some aspects, the techniques described in this document relate to a battery pack assembly wherein the thermal barrier is secured adjacent to the cell stack using a plurality of compression pins.

[0015] In some aspects, the techniques described in this document relate to a battery pack assembly wherein the thermal barrier is secured adjacent to an end plate of the cell stack.

[0016] In some aspects, the techniques described herein relate to a method for venting a battery cell, including: positioning a thermal barrier adjacent a plurality of battery cells, the thermal barrier comprising a plurality of deflector shrouds; moving at least one of the deflector shrouds within the plurality of deflector shrouds from a closed position to an open position in response to a flow of venting byproducts at the deflector shroud; and redirecting the flow of venting byproducts using the at least one of the deflector shrouds.

[0017] In some aspects, the techniques described in this document relate to a method that further includes scoring the thermal barrier to form the plurality of deflector hoods.

[0018] In some aspects, the techniques described in this document relate to a method that further includes scoring the thermal barrier by cutting the thermal barrier.

[0019] In some aspects, the techniques described in this document relate to a process wherein the deflector hoods are "C-" shaped.

[0020] In some aspects, the techniques described in this document relate to a method wherein at least one of the deflector hoods is in a fully open position during diverting.

[0021] In some aspects, the techniques described herein relate to a method wherein the plurality of battery cells are arranged along a cell stack axis, wherein redirecting includes redirecting the flow of vent byproducts from moving outwardly away from the plurality of battery cells to moving along the cell stack axis.

[0022] The embodiments, examples, and alternatives of the preceding paragraphs, the claims, or the following description and drawings, including any of their various aspects or respective individual features, may be considered independently of one another or in any combination. Features described in connection with one embodiment are applicable to all embodiments, unless such features are inconsistent. SHORT DESCRIPTION OF THE CHARACTERS

[0023] The various features and advantages of the disclosed examples will become apparent to those skilled in the art from the detailed description. The figures accompanying the detailed description may be briefly described as follows: Fig. 1 illustrates a side view of an electrified vehicle having a battery pack. Fig. 2 illustrates a partially enlarged view of the battery pack of Fig. 1. Fig. 3 illustrates a perspective view of a battery array from the battery pack Fig. 2, if no battery cells are vented. Fig. 4 illustrates a perspective view of an exemplary battery cell from the battery pack Fig. 3, when the battery cell is vented. Fig. 5 illustrates the perspective view of the battery array of Fig. 3, if the battery cell is Fig. 4 is vented. Fig. 6 illustrates a close-up view of an area from Fig. 5. Fig. Figure 7 illustrates a top view of the battery pack from Fig. 2, with a housing cover removed to show a possible vent path within the housing. Fig. 6 illustrates a perspective view of a battery cell from the battery array Fig. 3. Fig. Figure 7 illustrates a close-up view of a portion of the battery array of Fig. 3, wherein a vent flap of the thermal barrier is in an open position. DETAILED DESCRIPTION

[0024] A typical traction battery pack includes a housing with an interior space. Arrays of battery cells are housed within the space along with other components. A thermal event in one or more of the battery cells within an array can cascade to other battery cells in the battery pack, including battery cells in other battery arrays.

[0025] This disclosure describes in detail an exemplary thermal barrier that helps thermally insulate a battery array. The thermal barrier can, if necessary, assist in directing venting byproducts from a venting battery cell to an area outside a battery pack and away from battery cells that are not being vented.

[0026] With reference to Fig. 1, an electrified vehicle 10 includes a traction battery pack 12, an electric machine 14, and wheels 16. The battery pack 12 supplies power to the electric machine 14, which converts the electrical power into torque to drive the wheels 16. The battery pack 12 may be a relatively high-voltage battery.

[0027] In the exemplary embodiment, the battery pack 12 is secured to an underbody 18 of the electrified vehicle 10. The battery pack 12 could be located elsewhere on the electrified vehicle 10 in other examples.

[0028] The electrified vehicle 10 is a fully electric vehicle. In other examples, the electrified vehicle 10 is a hybrid electric vehicle that can selectively drive the wheels using torque provided by an internal combustion engine instead of or in addition to an electric machine. In general, the electrified vehicle 10 could be any type of vehicle that includes a traction battery pack.

[0029] Now with reference to Fig. 2-4 with continued reference to Fig. 1, the battery pack 12 includes a housing 20 that, among other things, houses a plurality of battery arrays 30. The exemplary housing 20 includes a tray 32 and a lid 34. The exemplary housing 20 holds eight individual battery arrays 30.

[0030] In the exemplary embodiment, each of the battery arrays 30 includes a plurality of battery cells 40, end plates 42, a top plate 44, and a pair of thermal barriers 48. The battery cells 40 of each of the battery arrays 30 are arranged along a respective cell stack axis A. Within each of the battery arrays 30, the battery cells 40 are compressed along the cell stack axis A between the end plates 42.

[0031] The top plate 44 extends over the vertically upper surfaces of the battery cells 40. Vertical and horizontal, as used in this disclosure, are understood with reference to the ground and a general orientation of the vehicle 10 during operation.

[0032] In the exemplary embodiment, the thermal barriers 48 are disposed along opposite outer surfaces of the battery cells 40. In other examples, the thermal barriers 48 could be disposed along other surfaces of the battery array 30, such as along an outer surface of the battery array 30.

[0033] The thermal barriers 48, in this example, may include a plurality of woven fibers. The thermal barriers 48 may be mica-based. In another example, the thermal barrier 48 may instead or additionally include nonwoven fibers. The thermal barriers 48 are thermal insulators. The thermal barriers 48 may be considered a thermal cover.

[0034] In one embodiment, the battery cells 40 are lithium-ion pouch cells. However, within the scope of this disclosure, battery cells having other geometries (cylindrical, prismatic, etc.), other chemistries (nickel-metal hydride, lead-acid, etc.), or both could alternatively be used.

[0035] Each of the exemplary battery cells 40 includes a pair of tab terminals 50 extending from the shell 52. Within a given one of the battery arrays 30, the individual battery cells 40 may be electrically connected to one another. To provide these electrical connections, the tab terminals 50 of the battery cells 40 may be connected to the tab terminals 50 of other battery cells 40, to a bus bar of the battery array 30, or both.

[0036] From time to time, pressure and temperature within one of the battery cells 40 may increase and rupture the housing 52 to provide an opening 54 in the housing 52. The battery cell 40 then expels venting byproducts V through the opening 54. From the opening 54, the venting byproducts V flow away from the cell stack axis A and onto the thermal barrier 48. Although a single one of the battery cells 40 is illustrated as being vented, more than one of the battery cells 40 may be vented simultaneously.

[0037] An accumulation of venting byproducts V between the thermal barrier 48 and other battery cells 40 that are not vented may increase thermal energy levels in those other battery cells 40, which may cause the venting event to cascade to those other battery cells 40.

[0038] Now with reference to Fig. 5-7 and with further reference to Fig. 1-4, the thermal barrier 48 is thus equipped with a plurality of apertures 60, which, when no cells 40 are being vented, are covered by the respective deflector shroud 62. When venting byproducts V move against a bottom side 64 of one of the deflector shrouds 62, the deflector shroud 62 moves to allow flow through the aperture 60. The bottom sides 64 of each deflector shroud 62 face the battery cells 40.

[0039] In this example, when a stream of vent byproducts V moves against the underside 64 of the deflector hood 62, the deflector hood 62 can be moved from the closed position to an open position. Each deflector hood 62 is thus configured to move from a closed position to an open position in response to a stream of vent byproducts at the deflector hood 62.

[0040] With reference to the deflector hood 62A, the deflector hood 62A in the closed position covers the aperture 60A in the thermal barrier 48 when the deflector hood 62A is in the closed position ( Fig. 3). The deflector hood 62A in the open position - here a fully open position, which is Fig. 5 and Fig. 6, a portion of the aperture 60A is exposed to allow some flow of vent byproducts through the aperture 60A, while still partially covering the aperture 60A. In this position, the deflector hood 62A is hood-shaped.

[0041] Because the deflector shroud 62A partially covers the aperture 60A in the fully open position, the flow of vent byproducts V through the aperture 60A contacts the bottom surface 64 of the deflector shroud 62A. The contact redirects the vent byproducts V. Specifically, the vent byproducts V initially move in a first direction D1 through the aperture 60A. After contacting the bottom surface 64 of the deflector shroud 62A, the vent byproducts V are redirected to flow in a second direction D2 that is different from the first direction D1.

[0042] The vent byproducts V moving in the second direction D2, in this example, move toward the outer regions of the battery pack 12 and away from other battery arrays 30. After reaching a wall of the shell 32, the vent byproducts V have cooled slightly. The vent byproducts V may then flow within the battery pack 12 to one or more enclosure vents 68, which release the vent byproducts V into an ambient area around the battery pack 12. The deflector shrouds 62A may be configured to direct vent byproducts V in other directions. In some examples, the vent byproducts V could be directed inward toward a center of the battery pack 12.

[0043] In this example, the thermal barrier 48 includes a plurality of notches 70 that form the deflector hoods 62. The notches 70 have an arcuate, "C" profile. The apertures 60 may be crescent-shaped. Each of the notches 70 forms one of the deflector hoods 62. Due to the shape of the notches 70, the deflector hoods 62 have a fish-scale shape. The thermal barrier 48 may be cut to form the notches 70.

[0044] In another example, the cuts 70 are a notched region of the thermal barrier 48. The notched region may form the deflector hoods 62 using perforations. The thermal barrier 48 may be cut to form the perforations. Such a transition of the deflector hood 62 from the closed position to an open position may require the venting byproducts V to rupture a portion of the thermal barrier 48.

[0045] The exemplary thermal barriers 48 are secured along the exterior sides of the battery arrays 30 using push pins 72 that extend through flaps 74 in the thermal barriers 48 to engage the top plate 44 of the respective battery array 30. In other examples, the thermal barriers 48 could instead or additionally be secured using an adhesive.

[0046] Although shown along the outer sides, the thermal barriers 48 having deflector shrouds 62 could instead or additionally be placed in other areas. For example, the thermal barriers 48 could be placed adjacent to other sides of the battery arrays 30, such as along the vertical top of the battery arrays 30 instead of the top plate 44. The thermal barriers 48 with deflector shrouds 62 could be positioned along the vertical top of the battery cells 40 if the battery cells 40 tend to open (i.e., vent) through the vertical tops of the battery cells 40.

[0047] The thermal barriers 48 could also be disposed along the end plates 42 to block the transfer of thermal energy from the battery arrays 30 on one side of the battery pack 12 to the battery arrays 30 on the other side of the battery pack 12. If they are disposed along the end plates 42 such that the end plates 42 are sandwiched between battery cells 40 and a thermal barrier, the thermal barrier may not include the deflector shrouds 62.

[0048] An exemplary method for venting a battery pack using the exemplary thermal barriers 48 includes positioning the thermal barrier 48 with the deflector shrouds 62 adjacent the battery cells 40. Next, in response to a flow of venting byproducts at the deflector shroud 62, the method moves at least one of the deflector shrouds 62 from a closed position to an open position, which then redirects the flow of venting byproducts. Redirecting includes redirecting the flow of venting byproducts V from moving outwardly away from the plurality of battery cells 40 to moving along the cell stack axis A.

[0049] The foregoing description is exemplary and not restrictive in nature. Variations and modifications of the disclosed examples may occur to those skilled in the art without necessarily departing from the spirit of this disclosure. Accordingly, the scope of protection afforded by this disclosure can only be determined by reading the following claims.

Claims

[1] Battery pack assembly comprising: a cell stack comprising a plurality of battery cells; a thermal barrier adjacent to the cell stack; and a plurality of deflector hoods included within the thermal barrier, each deflector hood configured to move from a closed position to an open position in response to a flow of vent byproducts at the deflector hood. [2] The battery pack assembly of claim 1, wherein each deflector hood has a bottom surface facing the plurality of battery cells, the flow of vent byproducts contacting the bottom surface to move the deflector hood from the closed position to the open position. [3] The battery pack assembly of claim 1, wherein the deflector shroud in the closed position covers an aperture in the thermal barrier, and the deflector shroud in the open position allows some flow through the aperture while partially covering the aperture such that a flow of the vent byproducts through the opening contacts a bottom surface of the deflector shroud and is redirected from flows in a first direction to flows in a second direction different from the first direction, and wherein the open position is optionally a fully open position. [4] The battery pack assembly of claim 1, wherein the thermal barrier includes a plurality of notched regions, each notched region forming one of the deflector hoods within the plurality of deflector hoods, and optionally wherein each notched region within the plurality of notched regions is arcuate. [5] The battery pack assembly of claim 1, wherein the thermal barrier includes a plurality of notches, each notch forming one of the deflector hoods within the plurality of deflector hoods, and optionally wherein each notch within the plurality of notches has a C-shaped profile. [6] The battery pack assembly of claim 1, wherein each deflector hood within the plurality of deflector hoods is hood-shaped. [7] The battery pack assembly of claim 1, wherein the thermal barrier is mica-based. [8] The battery pack assembly of claim 1, wherein the plurality of battery cells are arranged along a cell stack axis, the thermal barrier being adjacent to an exterior of the cell stack, the deflector shroud being configured to guide a current traveling away from the cell stack axis to travel along the cell stack axis. [9] The battery pack assembly of claim 1, wherein the thermal barrier is secured using a plurality of compression pins adjacent to the cell stack. [10] The battery pack assembly of claim 1, wherein the thermal barrier is secured adjacent to an end plate of the cell stack. [11] A method for venting a battery cell, comprising: Positioning a thermal barrier adjacent to a plurality of battery cells, the thermal barrier comprising a plurality of deflector hoods; Moving at least one of the deflector hoods within the plurality of deflector hoods from a closed position to an open position in response to a flow of vent byproducts at the deflector hood; and Diverting the flow of vent by-products using at least one of the deflector hoods. [12] The method of claim 11, further comprising scoring the thermal barrier to form the plurality of deflector hoods. [13] The method of claim 11, further comprising notching the thermal barrier by cutting the thermal barrier, and wherein the deflector hoods are optionally "C"-shaped. [14] The method of claim 13, wherein the at least one of the deflector hoods is in a fully open position during the diverting. [15] The method of claim 13, wherein the plurality of battery cells are arranged along a cell stack axis, wherein the redirecting includes redirecting the flow of vent byproducts from moving outwardly away from the plurality of battery cells to moving along the cell stack axis.

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