Thermal barrier system for use within traction battery pack

Abstract

The present disclosure provides a thermal barrier system for use within a traction battery pack. A thermal barrier system for suppressing thermal energy transfer inside a traction battery pack is provided. An exemplary thermal barrier system may include one or more thermal barrier assemblies disposed between adjacent battery cell packs of a cell stack. Each thermal barrier assembly may include a mica core, a first ceramic foam layer, a second ceramic foam layer, a first glass silicone layer, and a second glass silicone layer. In some embodiments, the thermal barrier system may additionally include one or more cell expansion pad assemblies and / or one or more thermal barriers.

Description

[0001] Cross-reference to related applications

[0002] This application claims the benefit of U.S. Provisional Application No. 63 / 679,332, filed on August 5, 2024, which is incorporated herein by reference in its entirety. Technical Field

[0003] This disclosure generally relates to traction battery packs, and more specifically to thermal barrier systems for managing the transfer of thermal energy within traction battery packs. Background Technology

[0004] Electrified vehicles include a traction battery pack that powers the vehicle's motor and other electrical loads. The traction battery pack comprises multiple battery cells and various other internal battery components that support the propulsion of the electric vehicle. Summary of the Invention

[0005] A traction battery pack according to an exemplary aspect of this disclosure particularly includes: a cell stack comprising a first battery cell group, a second battery cell group, and a thermal barrier assembly arranged to limit heat transfer between the first battery cell group and the second battery cell group. The thermal barrier assembly includes a mica core, a first ceramic foam layer, a second ceramic foam layer, a first glass-silicone resin layer, and a second glass-silicone resin layer.

[0006] In another non-limiting embodiment of the aforementioned traction battery pack, the cell stack includes a cell expansion pad assembly disposed between the first battery cell group and the end plate.

[0007] In another non-limiting embodiment of the aforementioned traction battery pack, the cell expansion pad assembly includes a ceramic foam layer sandwiched between a third glass silicone resin layer and a fourth glass silicone resin layer.

[0008] In another non-limiting embodiment of the aforementioned traction battery pack, the cell stack includes a thermal barrier disposed between the second and third battery cell groups.

[0009] In another non-limiting embodiment of the aforementioned traction battery pack, the thermal barrier assembly comprises ceramic foam.

[0010] In another non-limiting embodiment of the aforementioned traction battery pack, the first battery cell group and the second battery cell group each include at least two battery cells.

[0011] In another non-limiting embodiment of the aforementioned traction battery pack, the mica core is sandwiched between the first ceramic foam layer and the second ceramic foam layer.

[0012] In another non-limiting embodiment of the aforementioned traction battery pack, the first glass silicone layer is adjacent to the first ceramic foam layer, and the second glass silicone layer is adjacent to the second ceramic foam layer.

[0013] In another non-limiting embodiment of the aforementioned traction battery pack, the multilayer thermal barrier assembly includes a thickness of approximately 2.0 mm.

[0014] In another non-limiting embodiment of the aforementioned traction battery pack, the mica core has a thickness of about 0.3 mm, the first ceramic foam layer and the second ceramic foam layer each have a thickness of about 0.65 mm, and the first glass silicone resin layer and the second glass silicone resin layer each have a thickness of about 0.2 mm.

[0015] In another non-limiting embodiment of the aforementioned traction battery pack, the multilayer thermal barrier assembly includes a thickness of approximately 3.0 mm.

[0016] In another non-limiting embodiment of the aforementioned traction battery pack, the mica core has a thickness of about 0.8 mm, the first ceramic foam layer and the second ceramic foam layer each have a thickness of about 0.9 mm, and the first glass silicone resin layer and the second glass silicone resin layer each have a thickness of about 0.2 mm.

[0017] In another non-limiting embodiment of the aforementioned traction battery pack, the multilayer thermal barrier assembly includes a thickness of approximately 4.0 mm.

[0018] In another non-limiting embodiment of the aforementioned traction battery pack, the mica core has a thickness of about 1.2 mm, the first ceramic foam layer and the second ceramic foam layer each have a thickness of about 1.2 mm, and the first glass silicone resin layer and the second glass silicone resin layer each have a thickness of about 0.2 mm.

[0019] In another non-limiting embodiment of the aforementioned traction battery pack, the multilayer thermal barrier assembly includes a thickness of approximately 2.9 mm.

[0020] In another non-limiting embodiment of the aforementioned traction battery pack, the mica core has a thickness of about 0.5 mm, the first ceramic foam layer and the second ceramic foam layer each have a thickness of about 1.0 mm, and the first glass silicone resin layer and the second glass silicone resin layer each have a thickness of about 0.2 mm.

[0021] The embodiments, examples, and alternatives (including any of their various aspects or corresponding features) described in the foregoing paragraphs, claims, or the following description and drawings may be used independently or in any combination. Features described in connection with one embodiment are applicable to all embodiments unless such features are incompatible.

[0022] Various features and advantages of this disclosure will become apparent to those skilled in the art from the following detailed description. The accompanying drawings, which briefly describe the specific embodiments, are as follows. Attached Figure Description

[0023] Figure 1 An electric vehicle is shown schematically.

[0024] Figure 2 It shows Figure 1 The traction battery pack for electric vehicles.

[0025] Figure 3 It shows Figure 2 The cell stack of the traction battery pack.

[0026] Figure 4 yes Figure 3 An enlarged view of a selected portion of the battery cell stack.

[0027] Figure 5 This is an exploded view of an exemplary cell expansion pad assembly for a thermal barrier system.

[0028] Figure 6 This is an exploded view of an exemplary multilayer thermal barrier assembly of a thermal barrier system.

[0029] Figure 7 This is an exploded view of a selected portion of the cell stack of the traction battery pack.

[0030] Figure 8 This is an exploded view of a selected portion of another exemplary cell stack of a traction battery pack. Detailed Implementation

[0031] This disclosure details a thermal barrier system for suppressing heat transfer within a traction battery pack. An exemplary thermal barrier system may include one or more thermal barrier assemblies disposed between adjacent battery cell groups in a cell stack. Each thermal barrier assembly may include a mica core, a first ceramic foam layer, a second ceramic foam layer, a first glass-silicone layer, and a second glass-silicone layer. In some embodiments, the thermal barrier system may additionally include one or more cell expansion pad assemblies and / or one or more thermal barriers. These and other features are discussed in more detail in the following paragraphs of this detailed description.

[0032] Figure 1An electrified vehicle 10 is schematically illustrated. The electrified vehicle 10 may include any type of electrified powertrain. In this embodiment, the electrified vehicle 10 is a battery electric vehicle (BEV). However, the concepts described herein are not limited to BEVs and can be extended 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 embodiments, the powertrain of the electrified vehicle 10 may be equipped with an internal combustion engine, which may be used alone or in combination with other power sources to propel the electrified vehicle 10.

[0033] In the illustrated embodiment, the electrified vehicle 10 is depicted as an automobile. However, the electrified vehicle 10 may alternatively be a sports utility vehicle (SUV), van, pickup truck, or any other vehicle configuration. Although specific component relationships are shown in the accompanying drawings of this disclosure, the illustrations are not intended to limit the scope of this disclosure. The placement and orientation of the various components of the electrified vehicle 10 are schematically shown and may vary within the scope of this disclosure. Furthermore, the various drawings accompanying this disclosure are not necessarily drawn to scale, and some features may be enlarged or minimized to emphasize certain details of particular components or systems.

[0034] In one embodiment, the electrified vehicle 10 is a purely electric vehicle propelled solely by electricity (such as by one or more motors 12) without any assistance from an internal combustion engine. The motor 12 may operate as an electric motor, a generator, or both. The motor 12 receives electricity and may convert it into torque for driving one or more wheels 14 of the electrified vehicle 10.

[0035] Voltage bus 16 can electrically connect motor 12 to traction battery pack 18. Traction battery pack 18 is an exemplary electric vehicle battery. Traction battery pack 18 can be a high-voltage traction battery pack assembly including multiple groups of battery cells capable of outputting power to power motor 12 and / or other electrical loads of electric vehicle 10. Other types of energy storage devices and / or output devices may alternatively or additionally be used to power electric vehicle 10.

[0036] The traction battery pack 18 can be fixed to the bottom 20 of the electric vehicle 10. However, within the scope of this disclosure, the traction battery pack 18 can be located elsewhere on the electric vehicle 10.

[0037] Figure 2 , Figure 3 and Figure 4Additional details associated with the traction battery pack 18 of the electrified vehicle 10 are shown. The traction battery pack 18 may include one or more stacks 22 of cells 22 (e.g., 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 tray 28. The housing cover 26 may be vertically positioned above the housing tray 28. However, the housing cover 26 may be arranged below or to the side of the housing tray 28. Various terms such as “above,” “below,” “top,” and “bottom” are used in the various figures relative to the arrangement of components of the traction battery pack 18 and should not be considered limiting in any other way. These terms are for reference only when the traction battery pack 18 is mounted on... Figure 1 The general orientation of the electric vehicle 10. For the purposes of this disclosure, verticality is also referenced to the ground and how the traction battery pack 18 is oriented when mounted on the electric vehicle 10.

[0038] The housing cover 26 can be secured (e.g., bolted, welded, adhered, etc.) to the housing tray 28 to provide an internal area 30 for accommodating the cell stack 22 and other internal battery components of the traction battery pack 18 (e.g., busbars, control modules, and other electronics). Within the scope of this disclosure, the size, shape, and overall configuration of the housing assembly 24 can vary.

[0039] Each cell stack 22 may include multiple individual battery cells 32 arranged together along the cell stack axis A between opposing end plates 48. The battery cells 32 store and supply electricity to power various components in order to support the electric propulsion of the electrified vehicle 10.

[0040] In one embodiment, battery cell 32 is a lithium-ion pouch cell. However, within the scope of this disclosure, battery cells having other geometries (prismatic, cylindrical, etc.) and / or chemical properties (nickel-metal hydride, lead-acid, etc.) may be used alternatively.

[0041] Although a specific number of cell stacks 22 and battery cells 32 are shown in the various figures of this disclosure, the traction battery pack 18 may include any number of cell stacks 22, wherein each cell stack 22 has any number of individual battery cells 32.

[0042] Each battery cell 32 may include a first surface 34, a second surface 36 opposite to the first surface 34, a first end 38, a second end 40 opposite to the first end 38, a top side 42, and a bottom side 44 opposite to the top side 42. The first surface 34 and the second surface 36 form the primary side surface of the battery cell 32, and the first end 38, the second end 40, the top side 42, and the bottom side 44 form the secondary side surface of the battery cell 32. Therefore, the first surface 34 and the second surface 36 exhibit a larger surface area than any one of the first end 38, the second end 40, the top side 42, and the bottom side 44.

[0043] The tab terminal 46 can protrude outward from each of the first end 38 and the second end 40 of the battery cell 32. Therefore, the battery cell 32 can be considered to be "laterally oriented" within the cell stack 22. The tab terminal 46 can be connected to a bus (not shown) to electrically connect the battery cells 32 of each cell stack 22.

[0044] The cell stack 22 may additionally include a thermal barrier system 50 adapted to manage the transfer of thermal energy across the cell stack 22. The thermal barrier system 50 may include one or more cell expansion pad assemblies 52 and one or more multilayer thermal barrier assemblies 54.

[0045] In one embodiment, the cell stack 22 includes a pair of cell expansion pad assemblies 52. One cell expansion pad assembly 52 may be disposed between a first end plate in the end plate 48 and the battery cell 32 of the cell stack 22, and the other cell expansion pad assembly 52 may be disposed between a second end plate in the end plate 48 and the battery cell 32 of the cell stack 22.

[0046] One or more of the multilayer thermal barrier assemblies 54 may be arranged along the respective cell stack axis A of each cell stack 22. In one embodiment, a group of four individual battery cells 32 is separated by the thermal barrier assembly 54 along the cell stack axis a. In other embodiments, groups of two, three, or six battery cells 32 may be separated by the multilayer thermal barrier assembly 54 along the cell stack axis a. However, other configurations are contemplated within the scope of this disclosure, and those skilled in the art will appreciate that the cell stack 22 may include any number and arrangement of battery cells 32, cell expansion pad assemblies 52, and thermal barrier assemblies 54.

[0047] The battery cells 32 can be arranged such that one face 34, 36 of a battery cell 32 is in direct contact with one of the following: an adjacent face 34 or 36 of a battery cell 32, an adjacent multilayer thermal barrier assembly 54 of the cell stack 22, or an adjacent cell expansion pad assembly 52 of the cell stack 22. The battery cells 32, thermal barrier assemblies 54, and cell expansion pad assemblies 52 can be compressed relative to each other within the cell stack 22 to provide a face-to-face arrangement. For example, compression can be applied by the end plates 48 of the cell stack 22. However, other configurations are contemplated within the scope of this disclosure.

[0048] Currently, the main reference is... Figure 5 Each cell expansion pad assembly 52 of the thermal barrier system 50 can be configured as a multi-layer structure, which is configured to both accommodate cell expansion and limit conductive heat transfer across the cell stack 22. Each cell expansion pad assembly 52 may include a ceramic foam layer 56 sandwiched between a first glass silicone resin layer 58 and a second glass silicone resin layer 60. The ceramic foam layer 56, the first glass silicone resin layer 58, and the second glass silicone resin layer 60 may be bonded or otherwise fixed together using any known technology to form an integrated unit.

[0049] The ceramic foam layer 56 may include a ceramic material (e.g., silicon dioxide, etc.) that can be used to accommodate the expansion of the battery cells. The first glass-silicone layer 58 and the second glass-silicone layer 60 may each include an expansive material that can be activated in response to a thermal event in one or more battery cells 32 when the temperature at or near the cell stack 22 exceeds a predefined temperature threshold (e.g., about 200°C). Once activated, the heat-absorbing expansive material can absorb the heat energy generated during the thermal event and can suppress a portion of the convection effect of hot gases to minimize the thermal impact on adjacent battery cells 32 and / or adjacent cell stacks 22 of the traction battery pack 18.

[0050] In an embodiment, the total thickness of each cell expansion pad assembly 52 (e.g., a dimension extending parallel to the length of the cell stack 22 along the cell stack axis A) is approximately 1.7 mm, wherein the ceramic foam layer 56 has a thickness of 1.3 mm and the first glass silicone resin layer 58 and the second glass silicone resin layer 60 each have a thickness of approximately 0.2 mm. However, other thicknesses are conceivable within the scope of this disclosure. In this disclosure, the term “approximately” indicates that the expressed quantity or range does not need to be precise, but can be approximate and / or larger or smaller, thereby reflecting acceptable tolerances, conversion factors, measurement errors, etc.

[0051] Now for reference Figure 6Each multi-layer thermal barrier assembly 54 of the thermal barrier system 50 can be configured as a multi-layer structure, which is configured to limit conductive heat transfer across the cell stack 22. For example, the multi-layer thermal barrier assembly 54 can be arranged to limit conductive inter-cell heat transfer across each cell stack 22 of the traction battery pack 18.

[0052] Each multilayer thermal barrier assembly 54 may include a mica core 62, a first ceramic foam layer 64, a second ceramic foam layer 66, a first silicone glass layer 68, and a second silicone glass layer 70. The mica core 62, the first ceramic foam layer 64, the second ceramic foam layer 66, the first silicone glass layer 68, and the second silicone glass layer 70 may be bonded or otherwise fixed together using any known technique to form an integrated unit. The mica core 62 may be sandwiched between the first ceramic foam layer 64 and the second ceramic foam layer 66. The first silicone glass layer 68 may be adjacent to the first ceramic foam layer 64, and the second silicone glass layer 70 may be adjacent to the second ceramic foam layer 66.

[0053] The mica core 62 is a heat-resistant structure configured to provide an effective barrier against cell particle effluent during battery thermal events. The first ceramic foam layer 64 and the second ceramic foam layer 66 may comprise ceramic materials (e.g., silicon dioxide, etc.) configured to help dissipate heat energy and distribute it across the first glass silicone resin layer 68 and the second glass silicone resin layer 70, thereby helping to endothermically activate these layers during thermal events.

[0054] The first glass silicone resin layer 68 and the second glass silicone resin layer 70 may each include an expansive material that can be activated in response to a thermal event in one or more of the battery cells 32 when the temperature exceeds a predefined temperature threshold (e.g., about 200°C). Once activated, the heat-absorbing expansive material can absorb the thermal energy during the thermal event and can suppress a portion of the convection effect of hot gases to minimize the thermal impact on adjacent battery cells 32 within the cell stack 22.

[0055] In one embodiment, the total thickness of each multilayer thermal barrier assembly 54 (e.g., a dimension extending parallel to the length of the cell stack 22 along the cell stack axis A) is about 2.0 mm, wherein the mica core 62 has a thickness of about 0.3 mm, the first ceramic foam layer 64 and the second ceramic foam layer 66 each have a thickness of about 0.65 mm, and the first glass silicone resin layer 68 and the second glass silicone resin layer 70 each have a thickness of about 0.2 mm.

[0056] In yet another embodiment, the total thickness of each multilayer thermal barrier assembly 54 is about 2.9 mm, wherein the mica core 62 has a thickness of about 0.5 mm, the first ceramic foam layer 64 and the second ceramic foam layer 66 each have a thickness of about 1.0 mm, and the first glass silicone resin layer 68 and the second glass silicone resin layer 70 each have a thickness of about 0.2 mm.

[0057] In another embodiment, the total thickness of each multilayer thermal barrier assembly 54 is about 3.0 mm, wherein the mica core 62 has a thickness of about 0.8 mm, the first ceramic foam layer 64 and the second ceramic foam layer 66 each have a thickness of about 0.9 mm, and the first glass silicone resin layer 68 and the second glass silicone resin layer 70 each have a thickness of about 0.2 mm.

[0058] In yet another embodiment, the total thickness of each multilayer thermal barrier assembly 54 is about 4.0 mm, wherein the mica core 62 has a thickness of about 1.2 mm, the first ceramic foam layer 64 and the second ceramic foam layer 66 each have a thickness of about 1.2 mm, and the first glass silicone resin layer 68 and the second glass silicone resin layer 70 each have a thickness of about 0.2 mm.

[0059] The examples above are merely illustrative, and other thicknesses are conceivable within the scope of this disclosure. The actual thickness of each layer of the multilayer thermal barrier assembly described herein may vary depending on the thermal requirements of the cell stack 22 and other factors.

[0060] It is worth noting that although the thermal barrier system 50 is described above as having both the cell expansion pad assembly 52 and the multilayer thermal barrier assembly 54, other thermal barrier system implementations may be provided within the scope of this disclosure, including those thermal barrier system implementations that omit the cell expansion pad assembly 52.

[0061] Figure 7 A selected portion of another exemplary cell stack 122 that can be employed within a traction battery pack is shown. The cell stack 122 may include a thermal barrier system 150 configured to manage the transfer of thermal energy across the cell stack 122. The thermal barrier system 150 may include one or more cell expansion pad assemblies 152, one or more multilayer thermal barrier assemblies 154, and one or more thermal barriers 172.

[0062] A cell expansion pad assembly 152 can be arranged between the end plate 48 and the first battery cell group 174 of the cell stack 122. The first battery cell group 174 may include two or more battery cells 32. Although in Figure 7 The height is not shown in the schematic depiction, but the additional cell expansion pad assembly 152 can be arranged between the second end plate and another battery cell group of the cell stack 122.

[0063] The cell expansion pad assembly 152 can be configured as a multi-layer structure, which is configured to both accommodate the expansion of the battery cells and limit the conductive heat transfer across the cell stack 22. The cell expansion pad assembly 152 may include a ceramic foam layer 156 sandwiched between a first glass silicone resin layer 158 and a second glass silicone resin layer 160.

[0064] The ceramic foam layer 156 may include a ceramic material (e.g., silicon dioxide, etc.) that can be used to accommodate the expansion of the battery cells. The first glass-silicone layer 158 and the second glass-silicone layer 160 may each include an expansive material that can be activated in response to thermal events in one or more battery cells 32 when the temperature exceeds a predefined temperature threshold (e.g., about 200°C). Once activated, the heat-absorbing expansive material can absorb thermal energy and suppress a portion of the convection effect of hot gases to minimize the thermal impact on adjacent battery cells 32 and / or adjacent cell stacks within the traction battery pack.

[0065] In one embodiment, the total thickness of the cell expansion pad assembly 152 (e.g., a dimension extending parallel to the length of the cell stack 122 along the cell stack axis A) is approximately 1.7 mm, wherein the ceramic foam layer 156 has a thickness of 1.3 mm and the first glass silicone resin layer 158 and the second glass silicone resin layer 160 each have a thickness of approximately 0.2 mm. However, other thicknesses are contemplated within the scope of this disclosure.

[0066] A multi-layer thermal barrier assembly 154 may be arranged between the second battery cell group 176 and the third battery cell group 178 of the cell stack 122. The second battery cell group 176 and the third battery cell group 178 may each include two or more battery cells 32. Each multi-layer thermal barrier assembly 154 of the thermal barrier system 150 may be configured as a multi-layer structure, which is configured to limit conductive heat transfer across the cell stack 122. For example, the multi-layer thermal barrier assembly 154 may be arranged to limit conductive heat transfer between the second battery cell group 176 and the third battery cell group 178.

[0067] Each multilayer thermal barrier assembly 154 may include a mica core 162, a first ceramic foam layer 164, a second ceramic foam layer 166, a first silicone glass layer 168, and a second silicone glass layer 170. The mica core 162 may be sandwiched between the first ceramic foam layer 164 and the second ceramic foam layer 166. The first silicone glass layer 168 may be adjacent to the first ceramic foam layer 164, and the second silicone glass layer 170 may be adjacent to the second ceramic foam layer 166.

[0068] The mica core 162 is a heat-resistant structure configured to provide an effective barrier against cell particle effluent during thermal events. The first ceramic foam layer 164 and the second ceramic foam layer 166 may include ceramic materials (e.g., silicon dioxide, etc.) configured to help dissipate heat energy and distribute it across the first glass silicone resin layer 168 and the second glass silicone resin layer 170, thereby helping to endothermically activate these layers during thermal events.

[0069] The first glass-silicone layer 168 and the second glass-silicone layer 170 may each include an expansive material that can be activated in response to a thermal event in one or more of the battery cells 32 when the temperature exceeds a predefined temperature threshold (e.g., about 200°C). Once activated, the heat-absorbing expansive material can absorb thermal energy during the thermal event and can suppress a portion of the convection effect of hot gases to minimize any thermal impact on adjacent battery cells 32.

[0070] In one embodiment, the total thickness of the multilayer thermal barrier assembly 154 (e.g., a dimension extending parallel to the length of the cell stack 122 along the cell stack axis A) is approximately 3.0 mm, wherein the mica core 162 has a thickness of approximately 0.8 mm, the first ceramic foam layer 164 and the second ceramic foam layer 166 each have a thickness of approximately 0.9 mm, and the first glass silicone resin layer 168 and the second glass silicone resin layer 170 each have a thickness of approximately 0.2 mm. However, other thicknesses are contemplated within the scope of this disclosure.

[0071] A thermal barrier 172 may be disposed between the first battery cell assembly 174 and the second battery cell assembly 176. The thermal barrier 172 of the thermal barrier system 150 may be configured as a single-layer structure, the single-layer structure comprising a ceramic foam for limiting conductive heat transfer between the first battery cell assembly 174 and the second battery cell assembly 176.

[0072] In this embodiment, the total thickness of the thermal barrier 172 (e.g., a dimension extending parallel to the length of the cell stack 122 along the cell stack axis A) is approximately 1.0 mm. However, other thicknesses are conceivable within the scope of this disclosure.

[0073] The aforementioned alternation pattern between thermal barrier 172 and multilayer thermal barrier assembly 154 can be repeated along the entire length of cell stack 122. Therefore, one of the multilayer thermal barrier assemblies 154 can be arranged between every four battery cells 32 in cell stack 122. An additional first thermal barrier assembly (not shown) can be positioned between the last group of battery cells and the second end plate of cell stack 122.

[0074] Figure 8A selected portion of another exemplary cell stack 222 that can be employed within a traction battery pack is shown. The cell stack 222 may include a thermal barrier system 250 configured to manage the transfer of thermal energy across the cell stack 222. The thermal barrier system 250 may include one or more cell expansion pad assemblies 252, one or more multilayer thermal barrier assemblies 254, and one or more thermal barriers 272.

[0075] A cell expansion pad assembly 252 can be arranged between the end plate 48 and the first battery cell group 274 of the cell stack 222. The first battery cell group 274 may include two or more battery cells 32. Although in Figure 8 The height is not shown in the schematic depiction, but the additional cell expansion pad assembly 252 can be arranged between the second end plate and another battery cell group of the cell stack 222.

[0076] The cell expansion pad assembly 252 can be configured as a multi-layer structure, which is configured to both accommodate the expansion of the battery cells and limit the conductive heat transfer across the cell stack 222. The cell expansion pad assembly 252 may include a ceramic foam layer 256 sandwiched between a first glass silicone resin layer 258 and a second glass silicone resin layer 260.

[0077] The ceramic foam layer 256 may include a ceramic material (e.g., silicon dioxide, etc.) that can be used to accommodate the expansion of the battery cells. The first glass-silicone layer 258 and the second glass-silicone layer 260 may each include an expansive material that can be activated in response to a thermal event in one or more battery cells 32 when the temperature exceeds a predefined temperature threshold (e.g., about 200°C). Once activated, the heat-absorbing expansive material can absorb the thermal energy during the thermal event and can suppress a portion of the convection effect of hot gases to minimize the impact on adjacent battery cells 32 and / or adjacent cell stacks within the traction battery pack.

[0078] In one embodiment, the total thickness of the cell expansion pad assembly 252 (e.g., a dimension extending parallel to the length of the cell stack 222 along the cell stack axis A) is approximately 1.7 mm, wherein the ceramic foam layer 256 has a thickness of 1.3 mm and the first glass silicone resin layer 258 and the second glass silicone resin layer 260 each have a thickness of approximately 0.2 mm. However, other thicknesses are conceivable within the scope of this disclosure.

[0079] A multi-layer thermal barrier assembly 254 may be arranged between the third battery cell group 278 and the fourth battery cell group 280 of the cell stack 222. The third battery cell group 278 and the fourth battery cell group 280 may each include two or more battery cells 32. Each multi-layer thermal barrier assembly 254 of the thermal barrier system 250 may be configured as a multi-layer structure, which is configured to limit conductive heat transfer across the cell stack 222. For example, the multi-layer thermal barrier assembly 254 may be arranged to limit conductive heat transfer between the third battery cell group 278 and the fourth battery cell group 280.

[0080] Each multilayer thermal barrier assembly 254 may include a mica core 262, a first ceramic foam layer 264, a second ceramic foam layer 266, a first silicone glass layer 268, and a second silicone glass layer 270. The mica core 262 may be sandwiched between the first ceramic foam layer 264 and the second ceramic foam layer 266. The first silicone glass layer 268 may be adjacent to the first ceramic foam layer 264, and the second silicone glass layer 270 may be adjacent to the second ceramic foam layer 266.

[0081] The mica core 262 is a heat-resistant structure configured to provide an effective barrier against cell particle effluent during thermal events. The first ceramic foam layer 264 and the second ceramic foam layer 266 may include ceramic materials (e.g., silicon dioxide, etc.) configured to help dissipate heat energy and distribute it across the first glass silicone resin layer 268 and the second glass silicone resin layer 270, thereby helping to endothermally activate these layers during thermal events.

[0082] The first glass silicone resin layer 268 and the second glass silicone resin layer 270 may each include an expansive material that can be activated in response to a thermal event in one or more of the battery cells 32 when the temperature exceeds a predefined temperature threshold (e.g., about 200°C). Once activated, the heat-absorbing expansive material can absorb the thermal energy during the thermal event and can suppress a portion of the convection effect of hot gases to minimize the impact on adjacent battery cells 32.

[0083] In one embodiment, the total thickness of the multilayer thermal barrier assembly 254 (e.g., a dimension extending parallel to the length of the cell stack 222 along the cell stack axis A) is approximately 4.0 mm, wherein the mica core 262 has a thickness of approximately 1.2 mm, the first ceramic foam layer 264 and the second ceramic foam layer 266 each have a thickness of approximately 1.2 mm, and the first glass silicone resin layer 268 and the second glass silicone resin layer 270 each have a thickness of approximately 0.2 mm. However, other thicknesses are contemplated within the scope of this disclosure.

[0084] The first thermal barrier in thermal barrier 272 can be arranged between the first battery cell group 274 and the second battery cell group 276, and the second thermal barrier in thermal barrier 272 can be arranged between the second battery cell group 276 and the third battery cell group 278. The thermal barriers 272 of the thermal barrier system 250 can each be configured as a single-layer structure, the single-layer structure comprising ceramic foam for limiting conductive heat transfer between adjacent cell groups of the cell stack 222.

[0085] In this embodiment, the total thickness of each thermal barrier 272 (e.g., a dimension extending parallel to the length of the cell stack 122 along the cell stack axis A) is approximately 1.0 mm. However, other thicknesses are conceivable within the scope of this disclosure.

[0086] The pattern of alternating arrangement of two of the thermal barriers 272 and one of the multilayer thermal barrier assemblies 254 described above can be repeated along the entire length of the cell stack 222. Therefore, one of the multilayer thermal barrier assemblies 254 can be arranged between every six battery cells 32 in the cell stack 222. An additional telecommunications expansion pad assembly (not shown) can be positioned between the last group of battery cells and the second end plate of the cell stack 222.

[0087] Compared to known systems, the exemplary thermal barrier system of this disclosure is configured to provide increased thermal insulation. The proposed thermal barrier system can use a unique combination of materials to provide separation of exhaust gases.

[0088] While different non-limiting embodiments are shown having specific components or steps, the embodiments disclosed herein are not limited to those particular combinations. Some of the components or features from any of the non-limiting embodiments may be used in combination with features or components from any of the other non-limiting embodiments.

[0089] It should be understood that the same reference numerals identify corresponding or similar elements throughout all the figures. It should be understood that although particular arrangements of components are disclosed and shown in these exemplary embodiments, other arrangements may also benefit from the teachings of this disclosure.

[0090] The foregoing description should be interpreted as illustrative and not restrictive. Those skilled in the art will understand that certain modifications may be made within the scope of this disclosure. For these reasons, the appended claims should be examined to determine the true scope and content of this disclosure.

Claims

1. A traction battery pack, comprising: A battery cell stack, comprising a first battery cell group, a second battery cell group, and a multi-layer thermal barrier assembly, wherein the multi-layer thermal barrier assembly is arranged to limit the transfer of heat energy between the first battery cell group and the second battery cell group. The multilayer thermal barrier assembly includes a mica core, a first ceramic foam layer, a second ceramic foam layer, a first glass silicone resin layer, and a second glass silicone resin layer.

2. The traction battery pack according to claim 1, wherein the cell stack further includes a cell expansion pad assembly disposed between the first battery cell group and the end plate.

3. The traction battery pack according to claim 2, wherein the cell expansion pad assembly includes a ceramic foam layer sandwiched between a third glass silicone resin layer and a fourth glass silicone resin layer.

4. The traction battery pack according to any of the preceding claims, wherein the cell stack further includes a thermal barrier disposed between the second cell group and the third cell group.

5. The traction battery pack of claim 4, wherein the thermal barrier comprises ceramic foam.

6. The traction battery pack according to any of the preceding claims, wherein the first battery cell group and the second battery cell group each comprise at least two battery cells.

7. The traction battery pack according to any of the preceding claims, wherein the mica core is sandwiched between the first ceramic foam layer and the second ceramic foam layer.

8. The traction battery pack of claim 7, wherein the first glass silicone resin layer is adjacent to the first ceramic foam layer, and the second glass silicone resin layer is adjacent to the second ceramic foam layer.

9. The traction battery pack according to any of the preceding claims, wherein the multilayer thermal barrier assembly comprises a thickness of about 2.0 mm, and optionally, wherein the mica core comprises a thickness of about 0.3 mm, the first ceramic foam layer and the second ceramic foam layer each comprise a thickness of about 0.65 mm, and the first glass silicone resin layer and the second glass silicone resin layer each comprise a thickness of about 0.2 mm.

10. The traction battery pack of claim 1, wherein the multilayer thermal barrier assembly comprises a thickness of about 3.0 mm, and optionally, wherein the mica core comprises a thickness of about 0.8 mm, the first ceramic foam layer and the second ceramic foam layer each comprise a thickness of about 0.9 mm, and the first glass silicone resin layer and the second glass silicone resin layer each comprise a thickness of about 0.2 mm.

11. The traction battery pack of claim 1, wherein the multilayer thermal barrier assembly comprises a thickness of about 4.0 mm, and optionally, wherein the mica core comprises a thickness of about 1.2 mm, the first ceramic foam layer and the second ceramic foam layer each comprise a thickness of about 1.2 mm, and the first glass silicone resin layer and the second glass silicone resin layer each comprise a thickness of about 0.2 mm.

12. The traction battery pack of claim 1, wherein the multilayer thermal barrier assembly comprises a thickness of about 2.9 mm, and optionally, wherein the mica core comprises a thickness of about 0.5 mm, the first ceramic foam layer and the second ceramic foam layer each comprise a thickness of about 1.0 mm, and the first glass silicone resin layer and the second glass silicone resin layer each comprise a thickness of about 0.2 mm.

13. A traction battery pack comprising: First battery cell; Second battery cell; A multi-layer thermal barrier assembly, the multi-layer thermal barrier assembly being arranged to limit the transfer of heat energy between the first battery cell and the second battery cell; as well as The multilayer thermal barrier assembly includes a mica core, at least one ceramic foam layer, and at least one glass silicone resin layer.

14. The traction battery pack of claim 13, wherein the at least one ceramic foam layer comprises a first ceramic foam layer and a second ceramic foam layer, and the mica core is sandwiched between the first ceramic foam layer and the second ceramic foam layer, and optionally, wherein the at least one glass silicone resin layer comprises a first glass silicone resin layer positioned adjacent to the first ceramic foam layer and a second glass silicone resin layer positioned adjacent to the second ceramic foam layer.

15. The traction battery pack of claim 13 or 14, wherein the at least one ceramic foam layer comprises silicon dioxide, and the at least one glass silicone resin layer comprises an expandable material.

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