Thermal barrier for a traction battery pack and method for assembling a thermal barrier for a traction battery pack

Abstract

A thermal barrier assembly for a traction battery pack comprises a first outer shell; a second outer shell adjacent to the first outer shell to define an insulating cavity; and insulating material inserted between the first and second outer shells within the insulating cavity. Baffles extend into the insulating cavity and restrict movement of the insulating material within the cavity.

Description

FIELD OF TECHNOLOGY

[0001] This disclosure generally relates to a thermal barrier used in a traction battery pack. GENERAL STATE OF THE ART

[0002] A traction battery pack of an electrified vehicle may include groups of battery cells arranged in one or more cell stacks. Thermal barriers may be incorporated into the traction battery pack to help manage thermal energy. SUMMARY

[0003] In some aspects, the techniques described herein relate to a thermal barrier assembly for a traction battery pack, including: a first outer shell; a second outer shell adjacent to the first outer shell to define an insulation cavity; an insulation material interposed between the first outer shell and the second outer shell within the insulation cavity; and a plurality of baffles extending into the insulation cavity and restricting movement of the insulation material within the insulation cavity.

[0004] In some aspects, the techniques described in this document relate to a thermal barrier assembly for a traction battery pack, wherein the first outer shell, the second outer shell, and the insulating material provide a thermal barrier assembly configured to separate a first group of battery cells within a cell stack from a second group of battery cells within the cell stack.

[0005] In some aspects, the techniques described herein relate to a thermal barrier assembly for a traction battery pack, wherein the plurality of baffles includes a plurality of fins of the first outer shell, a plurality of fins of the second outer shell, or both.

[0006] In some aspects, the techniques described herein relate to a thermal barrier assembly for a traction battery pack, wherein the plurality of baffles include a plurality of first ribs extending from a bottom surface of the first outer shell and a plurality of second ribs extending from a bottom surface of the second outer shell, the plurality of first ribs contacting the plurality of second ribs to provide a plurality of aerogel-containing compartments.

[0007] In some aspects, the techniques described herein relate to a thermal barrier assembly for a traction battery pack, further including a first outer edge of the first outer shell and a second outer edge of the second outer shell, the first outer edge overlapping the second outer edge.

[0008] In some aspects, the techniques described herein relate to a thermal barrier assembly for a traction battery pack, wherein the first outer edge extends at least partially around a circumferential perimeter of the first outer shell, wherein the second outer edge extends at least partially around a circumferential perimeter of the second outer shell.

[0009] In some aspects, the techniques described in this document relate to a thermal barrier assembly for a traction battery pack, wherein the first outer edge overlaps with the second outer edge along three circumferential sides of the first outer edge.

[0010] In some aspects, the techniques described in this document relate to a thermal barrier assembly for a traction battery pack, wherein the insulating material is a particulate substance.

[0011] In some aspects, the techniques described in this document relate to a thermal barrier assembly for a traction battery pack, wherein the insulating material is an aerogel.

[0012] In some aspects, the techniques described in this document relate to a thermal barrier assembly for a traction battery pack, wherein the insulating material is fiberless.

[0013] In some aspects, the techniques described in this document relate to a thermal barrier assembly for a traction battery pack, wherein the first outer shell and the second outer shell are made of polymer-based materials.

[0014] In some aspects, the techniques described herein relate to a method of assembling a thermal barrier of a traction battery pack, including: placing a first outer shell adjacent a second outer shell; introducing an insulating material into an insulating cavity between the first outer shell and the second outer shell; influencing a distribution of the insulating material within the insulating cavity using a plurality of baffles; and compressing the insulating material between the first outer shell and the second outer shell to contain the insulating material within the insulating cavity.

[0015] In some aspects, the techniques described in this document relate to a method further including segmenting the insulation cavity using the plurality of baffles.

[0016] In some aspects, the techniques described herein relate to a method further including contacting a first plurality of ribs of the first outer shell with the second outer shell when segmenting the insulation cavity.

[0017] In some aspects, the techniques described herein relate to a method further including contacting the first plurality of ribs with a second plurality of ribs of the second outer shell when segmenting the insulation cavity.

[0018] In some aspects, the techniques described herein relate to a method further including, during compression, overlapping a first outer edge of the first outer shell with a second outer edge of the second outer shell.

[0019] In some aspects, the techniques described in this document relate to a method further including communicating air from the insulation cavity during compression.

[0020] In some aspects, the techniques described in this document relate to a method further including injecting the insulating material into the insulating cavity during insertion.

[0021] In some aspects, the techniques described in this document relate to a method further including placing the thermal barrier within a cell stack between a first group of battery cells and a second group of battery cells.

[0022] In some aspects, the techniques described in this document relate to a method further including disassembling a portion of a traction battery pack using the thermal barrier. 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 exemplary electrified vehicle. Fig. 2 illustrates an exploded perspective view of a battery pack from the electrified vehicle of Fig. 1, which schematically shows cell stacks of the battery pack. Fig. Figure 3 illustrates a sectional view taken along line 3-3 in Fig. 2. Fig. 4 to 4B illustrate different views of a thermal barrier from the battery pack of Fig. 2. Fig. Figure 5 illustrates a first outer shell and a second outer shell of a thermal barrier of the battery pack of Fig. 2. Fig. 6 to 6B illustrate various views of the first outer shell and the second outer shell being filled with an insulating material to provide the thermal barrier. DETAILED DESCRIPTION

[0024] This disclosure describes in detail exemplary thermal barriers for a traction battery pack and methods of manufacturing those thermal barriers.

[0025] The thermal barriers may include an insulating material, such as aerogel. The thermal barriers may include support features that facilitate even distribution of the insulating material throughout the thermal barrier. In exemplary embodiments, these support features are part of a shell or wrap for the thermal barrier.

[0026] In some examples, thermal barriers can compartmentalize areas of a traction battery pack, helping to contain and direct gas and debris vented from one or more battery cells during a thermal event. Directing the gas and debris away from other battery cells—other battery cells that are not vented—can help prevent the thermal event from cascading to those other battery cells.

[0027] With reference to Fig. 1, an electrified vehicle 10 includes a battery pack 14, an electric machine 18, and wheels 22. The battery pack 14 supplies power to an electric machine 18 that can convert electrical power into mechanical power to drive the wheels 22.

[0028] In the exemplary embodiment, the battery pack 14 is attached to an underbody 26 of the electrified vehicle 10. In other examples, the battery pack 14 could be located elsewhere on the electrified vehicle 10.

[0029] The electrified vehicle 10 is a fully electric vehicle. In other examples, the electrified vehicle 10 is a hybrid electric vehicle that selectively drives 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 battery pack.

[0030] With reference now to Fig. 2 and Fig. 3, the battery pack 14 includes a plurality of cell stacks 30 held within a battery pack housing 34. In the exemplary embodiment, the housing 34 includes a housing cover 38 and a housing shell 42. The housing cover 38 is secured to the housing shell 42 to provide an interior area 44 that houses the cell stacks 30. The housing cover 38 may be secured to the housing shell 42, for example, using mechanical fasteners (not shown).

[0031] Each of the cell stacks 30 includes a plurality of battery cells 50 (or simply "cells") and at least one thermal barrier 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.

[0032] Within each cell stack 30, the battery cells 50 are stacked side by side along the cell stack axis A. Within each cell stack 30, the thermal barriers 54 separate groups of battery cells 50 from other groups of battery cells 50. The groups of battery cells 50 may include one or more battery cells 50.

[0033] The battery cells 50 store and supply electrical power. Although a specific number of cell stacks 30 and cells 50 are illustrated in the various figures of this disclosure, the battery pack 14 could include any number of cell stacks 30 having any number of individual cells 50.

[0034] In one embodiment, the battery cells 50 are lithium-ion pouch cells. Alternatively, however, battery cells having other geometries (cylindrical, prismatic, etc.) or chemistries (nickel-metal hydride, lead acid, etc.), or both, could be utilized within the scope of this disclosure.

[0035] The exemplary battery cells 50 may include flat-pin terminals extending from an enclosure. For example, an aluminum foil may provide the enclosure.

[0036] From time to time, the pressure and thermal energy in one or more of the battery cells 50 may increase. The increase in pressure and thermal energy may be due, for example, to an overcharge condition. The increase in pressure and thermal energy may cause the associated battery cell 50 to rupture and release gas and debris.

[0037] The gases and debris may be released from the associated battery cell 50 through a designated vent in the enclosure, such as a membrane that yields in response to increased pressure, or through a ruptured portion of the associated battery cell 50. If a designated vent, the vent could be positioned to direct a flow of vented gas and debris away from the terminals of the battery cells 50.

[0038] The exemplary battery pack 14 includes crossbeam assemblies 66 disposed between cell stacks 30. The exemplary crossbeam assemblies 66 extend longitudinally in a direction parallel to the cell stack axes A. The crossbeam assemblies 66 and the cell stack axes A extend in a vehicle transverse direction (i.e., from a driver's side to a passenger side).

[0039] The thermal barriers 54 extend from the axis A outward past the cells 50 to contact the crossbeam assemblies 66 and / or the battery pack casing 34. This can compartmentalize groups of the battery cells 50. When one or more of the battery cells 50 within a group are vented, the venting byproducts V are directed through openings 70 within the crossbeam assemblies 66. The venting byproducts V thus flow into the crossbeam assemblies 66 rather than flowing axially to positions adjacent to other groups of battery cells 50 in the cell stack 30. From the crossbeam assemblies 66, the venting byproducts can be expelled from the battery pack 14 through a casing vent opening 72.

[0040] Venting byproducts V flowing adjacent to other battery cells 50 can increase the thermal energy levels in those battery cells 50 and lead to a cascading thermal event. Diverting thermal energy outward from axis A can help prevent the thermal energy from moving to other groups of battery cells 50 and prevent the thermal event from cascading to other groups of battery cells 50 that are not vented.

[0041] In this example, the thermal barriers 54 separate groups of four battery cells 50 within a given one of the cell stacks 30 from other groups of battery cells 50 within that cell stack 30. Thus, vent products V from a venting battery cell 50 flow adjacent to at most other battery cells 50 within that group before moving through the openings 70 rather than other groups of the battery cells 50.

[0042] With reference now to Fig. 4 to 5 and with further reference to Fig. 2 and Fig. 3, the thermal barriers 54 each include a first outer shell 74, a second outer shell 76, and an insulating material 82 interposed between the first outer shell 74 and the second outer shell 76. The first outer shell 74 includes a first shell outer edge 78 that extends at least partially around a circumferential perimeter of the first outer shell 74. The second outer shell 76 includes a second shell outer edge 80 that extends at least partially around a circumferential perimeter of the second outer shell 76.

[0043] The first outer shell 74 and the second outer shell 76 are made of polymer-based materials in this example. The first outer shell 74 and the second outer shell 76 could be made of other types of materials in other examples.

[0044] The first outer shell 74 and the second outer shell 76 are positioned adjacent to each other to define an insulation cavity 86 that holds the insulation material 82. In particular, the exemplary outer edge 78 of the first shell includes portions that overlap with portions of the outer edge 80 of the second shell. In this example, the outer edge 78 of the first shell overlaps the outer edge 80 of the second shell along three peripheral sides of the thermal barrier 54. Along the remaining fourth peripheral side, the outer edge 78 of the first shell is adjacent to the outer edge 80 of the second shell.

[0045] In this example, the first outer shell 74 includes a plurality of first baffles 90 extending from a bottom surface 94 of the first outer shell 74 into the insulation cavity 86. Furthermore, the second outer shell 76 includes a plurality of second baffles 98 extending from a bottom surface 100 of the second outer shell 76 into the insulation cavity 86.

[0046] The exemplary first baffles 90 are ribs that span the width of the thermal barrier 54 from the outer edge 78 of the first shell on one side of the thermal barrier 54 to the outer edge 78 of the first shell on the opposite side. The exemplary second baffles 98 similarly span the second outer shell 76. In other examples, the first baffles 90, the second baffles 98, or both could be pins instead of ribs, or could extend only partially across the thermal barrier 54. The ribs provided by the first baffles 90 and the second baffles 98 may have a rectangular cross-section and may, for example, be one millimeter thick and protrude approximately two millimeters from the respective bottom surface 94 or 100.

[0047] For the portions of the outer edge 78 of the first shell that overlap with portions of the outer edge 80 of the second shell, the portions may extend from the bottom surface 94 about three millimeters and may be about one millimeter thick.

[0048] The first outer shell 74 may be narrower and shorter than the second outer shell 76 to allow the outer edge 78 of the first shell to nest and overlap with the outer edge 80 of the second shell along the three sides of the thermal barrier 54.

[0049] In this example, the insulating material 82 is an aerogel powder. The insulating material is thus provided by a particulate substance. In other examples, the insulating material could be made of other materials that include other particulate substances.

[0050] It is understood that a uniform distribution of the insulating material 82 within the insulating cavity 86 of the thermal barrier 54 is desirable. This can help ensure that the thermal barrier 54 adequately blocks thermal energy along an entirety of the thermal barrier 54. As the vehicle 10 is driven, vibrations may tend to cause the insulating material 82 to gradually move and accumulate at a vertical bottom of the thermal barrier 54, resulting in an uneven distribution of the insulating material. In the past, a fiberglass mat was incorporated into thermal barriers to prevent movement of the insulating material within a thermal barrier. The fiberglass mat, among other things, increases the complexity of the thermal barrier.

[0051] The exemplary thermal barrier 54 can help maintain the position of the insulating material 82 without relying on a fiberglass mat. In the exemplary thermal barrier 54, the first baffles 90 contact the second baffles 98 to divide the insulation cavity 86 into a plurality of sub-cavities 102. Dividing the insulation cavity 86 in this manner can help restrict movement of the insulating material 82 within the insulation cavity 86. A quantity of the insulating material 82 is retained within each of the sub-cavities 102, blocking it from migrating into other sub-cavities 102.

[0052] While the exemplary partial cavities 102 are formed using both the first baffles 90 from the first outer shell 74 and the second baffles 98 from the second outer shell 76, in other examples, only the first baffles 90 could be used to form the partial cavities 102, or only the second baffles 98 could be used to form the partial cavities 102. That is, the second baffles 98 could be omitted, and the first baffles 90 could extend entirely from the bottom surface 94 of the first outer shell 74 to the bottom surface of the second outer shell 76. Accordingly, the first baffles 90 could be omitted, and the second baffles 98 could extend entirely from the bottom surface 94 of the first outer shell 74 to the bottom surface of the outer edge 80 of the second shell.

[0053] The exemplary first baffles 90 extend perpendicularly from the bottom surface 94 into the insulation cavity 86, and the exemplary second baffles 98 extend perpendicularly from the bottom surface 100 into the insulation cavity 86. In another example, the first baffles 90, the second baffles 98, or both could extend non-perpendicularly from the respective bottom surface 94 or the bottom surface 100. For example, the first baffles 90 could extend at an angle of forty-five degrees from the bottom surface 94.

[0054] A method of assembling the thermal barrier 54 may include the step of placing the first outer shell 74 and the second outer shell 76 adjacent to each other to provide the insulation cavity 86, as shown in Fig. 6 to 6B. At this time, the first guide vanes 90 do not directly contact the second guide vanes 98.

[0055] Next, the insulating material 82 is introduced into the insulating cavity 86. The insulating material 82 may be introduced via an injection process that draws the insulating material from an insulating material supply 88.

[0056] A portion of the insulating material 82 is captured and supported by the first baffles 90 and the second baffles 98 as the insulating material 82 is introduced. The first baffles 90 and the second baffles 98 thus prevent all of the insulating material 82 from accumulating at a vertical bottom of the insulation cavity.

[0057] Next, the first outer shell 74 and the second outer shell 76 are pressed together. Air A is forced out of the insulation cavity 86 while the insulation material 82 is compressed as the first outer shell 74 and the second outer shell 76 are pressed together. The first outer shell 74 and the second outer shell 76 are pressed together until the first baffles 90 contact the second baffles 98, as shown in Fig. 4 to 4B. After such contact, the insulation cavity 86 is divided into subcavities 102. Once the first baffles 90 are in contact with the second baffles 98, the insulation material 82 is contained within one of the subcavities 102.

[0058] The first outer shell 74 and the second outer shell 76 are then secured together using hot stamping, fasteners, adhesives, etc. The thermal barrier 54 can then be reoriented and positioned within one of the cell stacks 30 between a first group of battery cells 50 and a second group of battery cells 50, as shown in Fig. 2 to 3 shown.

[0059] Features of this disclosure include a thermal barrier having a fiberless construction, which may reduce complexity.

[0060] 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. Thus, the scope of this disclosure can only be determined by reading the following claims.

Claims

[1] Thermal barrier assembly for a traction battery pack, comprising: a first outer shell; a second outer shell adjacent to the first outer shell to define an insulation cavity; an insulating material interposed between the first outer shell and the second outer shell within the insulating cavity; and a plurality of baffles extending into the insulation cavity and restricting movement of the insulation material within the insulation cavity. [2] The thermal barrier assembly for a traction battery pack of claim 1, wherein the first outer shell, the second outer shell, and the insulating material provide a thermal barrier assembly configured to separate a first group of battery cells within a cell stack from a second group of battery cells within the cell stack. [3] The thermal barrier assembly for a traction battery pack of claim 1, wherein the plurality of baffles comprises a plurality of ribs of the first outer shell, a plurality of ribs of the second outer shell, or both. [4] The thermal barrier assembly for a traction battery pack of claim 1, wherein the plurality of baffles comprises a plurality of first ribs extending from a bottom surface of the first outer shell and a plurality of second ribs extending from a bottom surface of the second outer shell, the plurality of first ribs contacting the plurality of second ribs to provide a plurality of partial cavities. [5] The thermal barrier assembly for a traction battery pack of claim 1, further comprising a first outer edge of the first outer shell and a second outer edge of the second outer shell, the first outer edge overlapping the second outer edge, and optionally wherein the first outer edge extends at least partially around a circumferential perimeter of the first outer shell, the second outer edge extending at least partially around a circumferential perimeter of the second outer shell. [6] The thermal barrier assembly for a traction battery pack according to claim 5, wherein the first outer edge overlaps with the second outer edge along three circumferential sides of the first outer edge. [7] A thermal barrier assembly for a traction battery pack according to claim 1, wherein the insulating material is a particulate substance, an aerogel, or both. [8] A thermal barrier assembly for a traction battery pack according to claim 1, wherein the insulating material is fiberless. [9] The thermal barrier assembly for a traction battery pack according to claim 1, wherein the first outer shell and the second outer shell are made of polymer-based materials. [10] A method of assembling a thermal barrier of a traction battery pack, comprising: Placing a first outer shell adjacent to a second outer shell; introducing an insulating material into an insulating cavity between the first outer shell and the second outer shell; Influencing a distribution of the insulating material within the insulating cavity using a plurality of baffles; and Compressing the insulating material between the first outer shell and the second outer shell to contain the insulating material within the insulating cavity. [11] The method of claim 10, further comprising segmenting the insulation cavity using the plurality of baffles, and optionally further comprising contacting a first plurality of ribs of the first outer shell with the second outer shell when segmenting the insulation cavity. [12] The method of claim 11, further comprising contacting the first plurality of ribs with a second plurality of ribs of the second outer shell when segmenting the insulation cavity. [13] The method of claim 10, further comprising, during compression, overlapping a first outer edge of the first outer shell with a second outer edge of the second outer shell, and optionally further comprising, during compression, communicating air out of the insulation cavity. [14] The method of claim 10, further comprising injecting the insulating material into the insulating cavity during the insertion. [15] The method of claim 10, further comprising placing the thermal barrier within a cell stack between a first group of battery cells and a second group of battery cells, and optionally segmenting a portion of a traction battery pack using the thermal barrier.

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