Multi-layered thermal barrier for a battery pack

Abstract

A multi-layered thermal barrier of a traction battery pack includes an inner embedding structure provided by a first and second ceramic layer embedding a core layer, and a first and second foam layer embedding the inner embedding structure. The core layer could be glass or mica. Mica layers can be positioned between the inner embedding structure and the foam layers.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Application No. 63 / 585,443, filed on September 26, 2023, which is incorporated herein by reference. This application additionally claims the benefit of U.S. Provisional Application No. 63 / 594,623, filed on October 31, 2023, which is incorporated herein by reference. FIELD OF TECHNOLOGY

[0002] This disclosure relates generally to thermal barriers used within battery packs, and more particularly to multi-layer thermal barriers. GENERAL STATE OF THE ART

[0003] Battery packs can contain cell stacks with multiple battery cells. Within the cell stacks, a mica layer can be positioned between groups of battery cells. The mica layer can slow the heat spread between the groups of cells.

[0004] For example, with reference to Fig. 1, a prior art battery pack includes a cell stack comprising a plurality of battery cells 2. A prior art thermal barrier 4 includes a mica layer 6 disposed between groups of battery cells 2. Foam layers 8 positioned on opposite sides of the mica layer 6 can accommodate expansion of the battery cells 2. SUMMARY

[0005] In some aspects, the techniques described in this document relate to a multi-layer thermal barrier of a traction battery pack including: an internal encapsulation structure provided by first and second ceramic layers between which a core layer is sandwiched; and first and second foam layers between which the internal encapsulation structure is sandwiched.

[0006] In some aspects, the techniques described in this paper relate to multilayer thermal barriers where the core layer is glass.

[0007] In some aspects, the techniques described in this paper relate to a multilayer thermal barrier wherein the core layer is mica.

[0008] In some aspects, the techniques described in this document relate to a multi-layer thermal barrier, wherein the first and second ceramic layers are each thinner than the core layer.

[0009] In some aspects, the techniques described in this document relate to a multi-layer thermal barrier wherein the first and second ceramic layers are secured directly adherent to the core layer.

[0010] In some aspects, the techniques described herein relate to a multi-layer thermal barrier further including first and second mica layers, wherein the first mica layer is disposed between the first ceramic layer and the first foam layer, the second mica layer is disposed between the second ceramic layer and the second foam layer.

[0011] In some aspects, the techniques described in this document relate to a multilayer thermal barrier wherein the core layer is a third mica layer.

[0012] In some aspects, the techniques described in this paper relate to multilayer thermal barriers where the core layer is glass.

[0013] In some aspects, the techniques described in this document relate to a multi-layer thermal barrier, wherein the first mica layer is adhesively secured to both the first foam layer and the first ceramic layer, wherein the second mica layer is adhesively secured to both the second foam layer and the second ceramic layer.

[0014] In some aspects, the techniques described in this document relate to a multi-layer thermal barrier, wherein the first foam layer is a first polyurethane foam layer, wherein the second foam layer is a second polyurethane foam layer.

[0015] In some aspects, the techniques described herein relate to a traction battery pack assembly having the multi-layer thermal barrier and further including a cell stack having a plurality of battery cells arranged along a cell stack axis, wherein the multi-layer thermal barrier is axially positioned between at least a first battery cell of the plurality of battery cells and at least a second battery cell of the plurality of battery cells.

[0016] In some aspects, the techniques described herein relate to a traction battery pack assembly including: a cell stack including at least one first battery cell, at least one second battery cell, and a multi-layer thermal barrier assembly arranged to limit thermal energy transfer between the at least one first battery cell and the at least one second battery cell, wherein the multi-layer thermal barrier assembly includes an internal embedding structure embedded between first and second foam layers.

[0017] In some aspects, the techniques described in this document relate to a traction battery pack assembly, wherein the internal encapsulation structure includes first and second ceramic layers encapsulating a core layer.

[0018] In some aspects, the techniques described in this document relate to a traction battery pack assembly wherein the core layer is mica.

[0019] In some aspects, the techniques described in this document relate to a traction battery pack assembly wherein the core layer is glass.

[0020] In some aspects, the techniques described in this document relate to a traction battery pack assembly, wherein the at least one first battery cell includes four first battery cells, wherein the at least one second battery cell includes four second battery cells.

[0021] In some aspects, the techniques described in this document relate to a traction battery pack assembly further including first and second mica layers, the first mica layer being disposed between the inner embedding structure and the first foam layer, the second mica layer being disposed between the inner embedding structure and the second foam layer.

[0022] In some aspects, the techniques described in this document relate to a traction battery pack assembly wherein the internal embedding structure includes a third mica layer.

[0023] 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 Fig. Figure 1 shows a schematic side view of a portion of a prior art cell stack incorporating a thermal barrier. Fig. Figure 2 schematically illustrates an electrified vehicle. Fig. 3 illustrates a traction battery pack of the electrified vehicle from Fig. 2. Fig. 4 illustrates a cell stack of the traction battery pack from Fig. 3. Fig. Figure 5 illustrates a close-up view of a portion of the cell stack of Fig. 4. Fig. Figure 6 illustrates a perspective view of a multi-layer thermal barrier assembly from the cell stack Fig. 5 according to an exemplary embodiment of the present disclosure. Fig. Figure 7 is a schematic end view of the multilayer thermal barrier assembly of Fig. 6. Fig. 8-23 illustrate multilayer thermal barriers according to other exemplary embodiments of the present disclosure. DETAILED DESCRIPTION

[0024] This disclosure describes multilayer thermal barrier assemblies for traction battery packs in detail. The multilayer thermal barrier assemblies can prevent the transfer of thermal energy within the traction battery pack. In some embodiments, the multilayer thermal barriers provide barriers to escaping particles along with heat dissipation and thermal insulation to contain thermal energy and delay or stop heat propagation between groups of battery cells. The multilayer thermal barriers can increase the time over which thermal energy is transferred through the thermally conductive interconnects. This can result in a longer propagation time or at least delayed heat propagation to cells within a cell stack.

[0025] Fig. 2 schematically illustrates an electrified vehicle 10. The electrified vehicle 10 may include any type of electrified powertrain. In one embodiment, the electrified vehicle 10 is a battery electric vehicle (BEV). However, the concepts described herein are not limited to BEVs and could extend to other electrified vehicles, including, but not limited to, hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), fuel cell vehicles, etc. Therefore, although not specifically shown in the exemplary embodiment, the powertrain of the electrified vehicle 10 could be equipped with an internal combustion engine, which can be used either alone or in combination with other power sources to propel the electrified vehicle 10.

[0026] In the illustrated embodiment, the electrified vehicle 10 is depicted as an automobile. However, the electrified vehicle 10 could alternatively be a sport utility vehicle (SUV), a van, a pickup truck, or any other vehicle configuration. Although a specific relationship of the components is illustrated in the figures of this disclosure, the illustrations are not intended to limit this disclosure. The placement and orientation of the various components of the electrified vehicle 10 are shown schematically and could vary within the scope of this disclosure. Furthermore, the various figures accompanying this disclosure are not necessarily drawn to scale, and some features may be exaggerated or minimized to emphasize certain details of a particular component or system.

[0027] In one embodiment, the electrified vehicle 10 is an all-electric vehicle powered solely by electric power, such as one or more electric machines 12, without any assistance from an internal combustion engine. The electric machine 12 may operate as an electric motor, an electric generator, or both. The electric machine 12 receives electric power and may convert the electric power into torque to drive one or more wheels 14 of the electrified vehicle 10.

[0028] A voltage bus 16 may electrically couple the electric machine 12 to a traction battery pack 18. The traction battery pack 18 is an exemplary battery of an electrified vehicle. The traction battery pack 18 may be a high-voltage traction battery pack assembly including a plurality of battery cell groupings capable of outputting electrical power to power the electric machine 12 and / or other electrical loads of the electrified vehicle 10. Alternatively or additionally, other types of energy storage devices and / or output devices could also be used to supply electrical power to the electrified vehicle 10.

[0029] The traction battery pack 18 may be secured to an underbody 20 of the electrified vehicle 10. However, in other examples, the traction battery pack 18 could be located at a different location on the electrified vehicle 10.

[0030] Fig. 3-5 illustrate additional details associated with the traction battery pack 18 of the electrified vehicle 10. The traction battery pack 18 may include one or more cell stacks 22 (e.g., the one shown) housed within an interior region 30 of a housing assembly 24. The housing assembly 24 of the traction battery pack 18 may include a housing cover 26 and a housing shell 28. The housing cover 26 is positioned vertically above the housing shell 28. However, the housing cover 26 could be disposed below or to one side of the housing shell 28. Various terms, such as "above," "below," "top," and "bottom," are used with reference to the arrangement of the components of the traction battery pack 18 in the various drawings and should otherwise not be considered limiting.These terms refer to the general orientation of the traction battery pack 18 when used in the electrified vehicle 10. Fig. 1. For the purposes of this disclosure, vertical also refers to the ground and how the traction battery pack 18 is oriented when installed in the electrified vehicle 10.

[0031] The housing cover 26 may be secured (e.g., bolted, welded, glued, etc.) to the housing shell 28 to provide the interior space 30 for housing the cell stacks 22 and other internal battery components (e.g., bus bars, control modules, and other electronics, etc.) of the traction battery pack 18. The size, shape, and configuration of the housing assembly 24 may vary within the scope of this disclosure.

[0032] Each cell stack 22 may include a plurality of individual battery cells 32 arranged together along a cell stack axis A between opposing end plates 48. The battery cells 32 store and supply electrical power to power various components to support the electric propulsion of the electrified vehicle 10.

[0033] In one embodiment, the battery cells 32 are lithium-ion pouch cells. However, within the scope of this disclosure, battery cells having other geometries (prismatic, cylindrical, etc.) and / or chemistries (nickel-metal hydride, lead-acid, etc.) could alternatively be used.

[0034] Although a specific number of cell stacks 22 and battery cells 32 are illustrated in the various figures of this disclosure, the traction battery pack 18 could include any number of cell stacks 22, with each cell stack 22 having any number of individual battery cells 32.

[0035] Each battery cell 32 may include a first surface 34, a second surface 36 opposite the first surface 34, a first end 38, a second end 40 opposite the first end 38, a top surface 42, and a bottom surface 44 opposite the top surface 42. The first surface 34 and the second surface 36 form major side surfaces of the battery cells 32, and the first end 38, the second end 40, the top surface 42, and the bottom surface 44 form minor side surfaces of the battery cell 32. The first surface 34 and the second surface 36 therefore have a larger surface area than any of the first end 38, the second end 40, the top surface 42, and the bottom surface 44.

[0036] A tab terminal 46 projects outwardly from each of the first end 38 and the second end 40 of the battery cells 32. The battery cells 32 can thus be considered "side-aligned" within the cell stacks 22. The tab terminals 46 can be connected to bus bars (not shown) to electrically connect the battery cells 32 of each cell stack 22.

[0037] The cell stack 22 includes one or more multi-layer thermal barrier assemblies 60 that may be arranged along the respective cell stack axis A of each cell stack 22. In one embodiment, groups of four individual battery cells 32 are separated by the multi-layer thermal barrier assemblies 60 along the cell stack axis A. However, other configurations are contemplated within the scope of this disclosure, and it should be apparent to those having the benefit of this disclosure that the cell stack 22 could include any number and any arrangement of battery cells 32 and multi-layer thermal barrier assemblies 60.

[0038] The battery cells 32 may be arranged such that the surfaces 34, 36 of one battery cell 32 are in direct contact with one of the surfaces 34 or 36 of an adjacent battery cell 32 or an adjacent thermal barrier assembly 60 of the cell stack 22. The battery cells 32, the thermal barrier assemblies 60, and cell expansion pads 62 may be held in compression relative to one another within the cell stack 22 to provide the opposing arrangement. The compression may be applied, for example, by the end plates 48 of the cell stack 22. However, other configurations are contemplated within the scope of this disclosure.

[0039] With reference to Fig. 7 and with continued reference to Fig. 2-6, the multi-layer thermal barrier 60 in this example includes an inner embedding structure 62 provided by a core layer 64 sandwiched between a first ceramic layer 66 and a second ceramic layer 68. In the multi-layer thermal barrier 60, the inner embedding structure 62 is sandwiched between a first foam layer 70 and a second foam layer 72.

[0040] In this example, core layer 64 is a glass-silicone layer approximately 0.5 millimeters thick. The first ceramic layer 66 and the second ceramic layer 68 are each thinner than core layer 64. The first ceramic layer 66 and the second ceramic layer 68 may be secured directly to core layer 64, for example, using an adhesive tape.

[0041] In a variation of the multilayer thermal barrier 60, the core layer 64 could be a mica layer instead of glass silicone.

[0042] The first foam layer 70 and the second foam layer 72 can accommodate expansion of the cells 32 along the A axis. The first foam layer 70 and the second foam layer 72 can be polyurethane foam. The first foam layer 70 and the second foam layer 72 can have a vertical height that is less than the other sections of the multi-layer thermal barrier 60.

[0043] The exemplary multi-layer thermal barrier 60 additionally includes a first mica layer 76 and a second mica layer 78. The first mica layer 76 is disposed between the first ceramic layer 66 and the first foam layer 70. The second mica layer is disposed between the second ceramic layer 68 and the second foam layer 72.

[0044] The first mica layer 76 can be directly adhered to both the first foam layer 70 and the first ceramic layer 66. The second mica layer 78 is adhered to both the second foam layer 72 and the second ceramic layer 68.

[0045] Additional exemplary embodiments of the multi-layer thermal barrier 60 will now be described in connection with Fig. 8-18. Some of the exemplary multilayer thermal barriers may include intumescent endothermic aerogel layers in an embedded configuration. The multilayer thermal barriers may also include fiberglass, steel, graphene, or a combination of these. Adhesives, such as adhesive tape, may be used to bond the layers.

[0046] The intumescent materials in some of these examples can be activated in response to a thermal event in one or more battery cells when the temperature exceeds 200°C. The aerogel layers in some of these examples are endothermic in nature and can absorb thermal energy during a thermal event and can retain some of the convection effects of hot gases to minimize the impact on neighboring cells.

[0047] The metal layers and / or graphene layers of some of these examples help to dissipate thermal energy and distribute thermal energy across the endothermic aerogel layers to activate the endothermic aerogel layers.

[0048] The examples that include an outer layer of mica may rely on this layer providing a barrier to cell particle effluents that may be discharged from one or more of the battery cells 32 during a thermal event.

[0049] With reference to Fig. 8, another exemplary embodiment of a multi-layer thermal barrier 80 for use in the battery pack 18 includes two aerogel layers 81, 82 sandwiched between steel layers 83, 84. Foam layers 85, 86 sandwich the aerogel layers 81, 82 and the steel layers 83, 84.

[0050] With reference to Fig. 9, another exemplary embodiment of a multi-layer thermal barrier 90 for use in the battery pack 18 includes three mica layers 91, 92, 93 alternating with fiberglass layers 94, 95. The mica layers 91, 92, 93 and the fiberglass layers 94, 95 are sandwiched between foam layers 96, 97.

[0051] With reference to Fig. 10, another exemplary embodiment of a multi-layer thermal barrier 100 for use in the battery pack 18 includes an adhesive layer 101, which may be a glass silicone tape with an adhesive backing, sandwiched between foam layers 102, 103.

[0052] With reference to Fig. 11, another exemplary embodiment of a multi-layer thermal barrier 110 for use in the battery pack 18 includes a steel layer 111 and two aerogel layers 112, 113 sandwiched between foam layers 114, 115.

[0053] With reference to Fig. 12, another exemplary embodiment of a multi-layer thermal barrier 120 for use in the battery pack 18 includes a ceramic layer 121 sandwiched between two steel layers 122, 123, which are then sandwiched between foam layers 125, 126. The multi-layer thermal barrier 120 may further include PET film layers.

[0054] With reference to Fig. 13, another exemplary embodiment of a multi-layer thermal barrier 130 for use in the battery pack 18 includes a ceramic layer 131 sandwiched between two soft mica layers 132, 133, which are then sandwiched between foam layers 134, 135.

[0055] With reference to Fig. 14, another exemplary embodiment of a multi-layer thermal barrier 140 for use in the battery pack 18 includes a mica layer 141, which may be hard mica, sandwiched between PET / graphene layers 142, 143 and aerogel layers 144, 145, which are then sandwiched between foam layers 146, 147. The mica layer 141 extends outward from the axis A of the cell stack 22 past the PET / graphene layers 142, 143. The mica layer 141 provides a picture frame structure around the PET / graphene layers 142, 143. The PET / graphene layers 142, 143 may be laminated together.

[0056] When a multilayer thermal barrier, such as multilayer thermal barrier 140, has a picture frame structure, one frame layer (here, mica layer 141) extends outward beyond another inner layer. The inner layer, the PET / graphene layers 142, 143, can be embedded in the frame layer. The edges of the inner layer, which may be sharp, are protected by the frame layer. This configuration eliminates the need for adhesive tape, which can save space.

[0057] With reference to Fig. 15, another exemplary embodiment of a multi-layer thermal barrier 150 for use in the battery pack 18 includes a hard mica layer 151 sandwiched between PET / steel layers 152, 153 and then aerogel layers 154, 155. These layers are then sandwiched between foam layers 156, 157. The hard mica 151 and the aerogel layers 154, 155 extend outward from the axis A of the cell stack 22 past the PET / steel layers 152, 153. The mica 151 and the aerogel layers 154, 155 provide a picture frame structure around the PET / steel layers 152, 153.

[0058] With reference to Fig. 16, another exemplary embodiment of a multi-layer thermal barrier 160 for use in the battery pack 18 includes a layer 161 of hard mica sandwiched between steel 162, 163 and soft mica layers 164, 165, which are then sandwiched between foam layers 166, 167.

[0059] With reference to Fig. 17, another exemplary embodiment of a multi-layer thermal barrier 170 for use in the battery pack 18 includes an aerogel layer 171 sandwiched between steel layers 172, 173 and the soft mica layers 174, 175. These layers are then sandwiched between foam layers 176, 177. The soft mica layers 174, 175 and the aerogel layer 171 extend outward from the axis A of the cell stack 22 past the steel layers 172, 173. The soft mica layers 174, 175 and the aerogel layer 171 provide a picture frame structure around the steel layers 172, 173.

[0060] With reference to Fig. 18, another exemplary embodiment of a multilayer thermal barrier 180 for use in the battery pack 18 includes a double aerogel layer 181, 182 sandwiched between graphene layers 183, 184, steel layers 185, 186, and then PET layers 187, 188. These layers are then sandwiched between the two foam layers 189.

[0061] Now with reference to Fig. 19-23, other exemplary multilayer thermal barriers may include at least one endothermic glass-silicone layer sandwiched between layers of another material. The endothermic layer may be activated in response to a thermal event in one or more battery cells when the temperature exceeds 200°C. The aerogel layers are endothermic in nature and can absorb thermal energy during a thermal event and can retain some of the convective effects of hot gases to minimize the impact on neighboring cells.

[0062] Ceramic coatings and glass silicone layers can help dissipate thermal energy and distribute thermal energy across the endothermic aerogel layers to activate the endothermic aerogel layers.

[0063] With reference to Fig. 19, another exemplary embodiment of a multi-layer thermal barrier 190 for use in the battery pack 18 includes a checkered mica layer 191 sandwiched between hard mica layers 192, 193 and then foam layers 194, 195. The checkered mica layer 191 may include mica material surrounded by air gaps or an endothermic filler, such as a mixture of sodium silicate (40-65%) and aluminum nitride (25-35%) or a mixture of sodium silicate (40-65%) and aluminum oxide (25-35%). The foam layers 194, 195 do not extend as far from the A axis as the other layers.

[0064] With reference to Fig. 20, another exemplary embodiment of a multi-layer thermal barrier 200 for use in the battery pack 18 includes an endothermic pouch layer 201 sandwiched between hard mica layers 202, 203 and then foam layers 204, 205. The endothermic pouch layer 201 includes a pouch made, for example, from polyimide or polyethylene terephthalate and filled with an endothermic material, such as sodium silicate. The pouch of the endothermic pouch layer 201 may additionally include foam and electrically insulating materials, such as aluminum nitrate and aluminum oxide. The foam layers 204, 205 do not extend as far as the other layers.

[0065] With reference to Fig. 21, another exemplary embodiment of a multi-layer thermal barrier 210 for use in the battery pack 18 includes a mica layer 211 sandwiched between ceramic layers 212, 213, which are then sandwiched between other mica layers 214, 215 and then foam layers 216, 217. The foam layers 216, 217 do not extend as far as the other layers.

[0066] With reference to Fig. 22, another exemplary embodiment of a multi-layer thermal barrier 220 for use in the battery pack 18 includes an aerogel layer 221 sandwiched between ceramic layers 222, 223, which are then sandwiched between mica layers 224, 225 and then foam layers 226, 227. The foam layers 226, 227 do not extend as far as the other layers.

[0067] With reference to Fig.23, another exemplary embodiment of a multi-layer thermal barrier 230 for use in the battery pack 18 includes a glass / silicone layer 231 sandwiched between ceramic layers 232, 233, which are then sandwiched between mica layers 234, 235 and then foam layers 236, 237. The foam layers 236, 237 do not extend as far as the other layers. A thickness of the glass / silicone layer 231 is 0.3 millimeters in this example.

[0068] Features of some of the disclosed examples may include multilayer thermal barriers comprising an intumescent endothermic aerogel layer to reduce thermal conductivity and absorb heat. An activation temperature for the layer may be approximately 200 degrees Celsius. Various combinations of steel layers, graphene layers, mica, and / or aerogel may be used to achieve high heat dissipation and thermal insulation values ​​at high temperatures using different combinations of steel, graphene with mica, and aerogel. The multilayer thermal barriers may include at least one checkered mica layer. The multilayer thermal barriers may include at least one ceramic layer.

[0069] Features of the disclosed examples may include multilayer thermal barriers comprising an intumescent endothermic aerogel layer to reduce thermal conductivity and absorb heat. An activation temperature for the layer may be approximately 200 degrees Celsius. Various combinations of steel layers, graphene layers, mica, and / or aerogel may be used to achieve high heat dissipation and thermal insulation values ​​at high temperatures using different combinations of steel, graphene with mica, and aerogel.

[0070] 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. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] US 63 / 585443

[0001] US 63 / 594623

[0001]

Claims

[1] Multi-layer thermal barrier of a traction battery pack, comprising: an inner embedding structure provided by a first and a second ceramic layer between which a core layer is embedded; and a first and a second foam layer between which the inner embedding structure is embedded. [2] A multilayer thermal barrier according to claim 1, wherein the core layer is glass. [3] The multilayer thermal barrier of claim 1, wherein the core layer is mica. [4] The multilayer thermal barrier of claim 1, wherein the first and second ceramic layers are each thinner than the core layer. [5] The multi-layer thermal barrier of claim 1, wherein the first and second ceramic layers are directly adherently secured to the core layer. [6] The multi-layer thermal barrier of claim 1, further comprising a first and a second mica layer, wherein the first mica layer is disposed between the first ceramic layer and the first foam layer, the second mica layer is disposed between the second ceramic layer and the second foam layer, and wherein the core layer is optionally a third mica layer. [7] A multilayer thermal barrier according to claim 6, wherein the core layer is glass. [8] The multi-layer thermal barrier of claim 6, wherein the first mica layer is adhesively secured to both the first foam layer and the first ceramic layer, wherein the second mica layer is adhesively secured to both the second foam layer and the second ceramic layer, and wherein the first foam layer is optionally a first polyurethane foam layer, wherein the second foam layer is a second polyurethane foam layer. [9] A traction battery pack assembly having the multi-layer thermal barrier of claim 1 and further comprising a cell stack having a plurality of battery cells arranged along a cell stack axis, wherein the multi-layer thermal barrier is axially positioned between at least a first battery cell of the plurality of battery cells and at least a second battery cell of the plurality of battery cells. [10] Traction battery pack assembly comprising: a cell stack including at least one first battery cell, at least one second battery cell, and a multi-layer thermal barrier assembly arranged to limit thermal energy transfer between the at least one first battery cell and the at least one second battery cell, wherein the multi-layer thermal barrier assembly includes an internal embedding structure embedded between first and second foam layers. [11] The traction battery pack assembly of claim 10, wherein the internal embedding structure includes first and second ceramic layers embedding a core layer. [12] The traction battery pack assembly of claim 11, wherein the core layer is mica or glass. [13] The traction battery pack assembly of claim 10, wherein the at least one first battery cell includes four first battery cells, wherein the at least one second battery cell includes four second battery cells. [14] The traction battery pack assembly of claim 10, further comprising a first and a second mica layer, wherein the first mica layer is disposed between the inner embedding structure and the first foam layer, the second mica layer is disposed between the inner embedding structure and the second foam layer. [15] The traction battery pack assembly of claim 14, wherein the inner embedding structure includes a third mica layer.

Images