Thermal insulation and dielectric insulation for battery packs

Abstract

A flexible thermal insulation body (10) for an electric vehicle battery pack (12) and an electric vehicle battery pack (12) having the flexible thermal insulation body are provided. The flexible thermal insulation body (10) has a composite wall comprising a refractory sheet having opposing first and second sides. A first pressure-sensitive adhesive layer is bonded to the first side of the refractory sheet. Further, a loosely woven polyetheretherketone (PEEK) layer is bonded to the second side of the refractory sheet, or a silicone rubber layer is bonded to the second side of the refractory sheet.

Description

[0001] Cross-references to related applications

[0002] This application claims the benefit of U.S. Provisional Application Serial No. 63 / 223,481, filed July 19, 2021, and priority of U.S. Application Serial No. 17 / 866,316, filed July 15, 2022, the entire contents of which are incorporated herein by reference. Background of the Invention 1. Technical Field

[0004] The present invention relates generally to various thermal and dielectric insulators, and more specifically to thermal and dielectric insulators for suppressing flames inside and from the battery pack. 2. Background Technology

[0006] As is well known, battery packs (including those used in electric vehicle applications) are encased or shielded by insulating materials. A common material used to form this insulation is fiberglass fabric. While fiberglass fabric insulation provides acceptable protection against contamination and ambient temperatures during normal use, it does not provide the necessary protection against the propagation of flames from the battery pack outwards or between the battery cells, for example, in the event of thermal runaway in one or more battery cells of an electric vehicle battery pack. There is a need to provide an insulation material that provides both dielectric protection for the battery pack and inhibits the propagation of flames from the battery pack outwards or between the battery cells. Summary of the Invention

[0007] The purpose of this disclosure is to provide a heat insulation for use with electric vehicle battery packs that at least meets the need to suppress the spread of flame from the battery pack and between the battery cells of the battery pack.

[0008] Another objective is to suppress the spread of flame from the battery pack and between the battery cells within the battery pack for 5 minutes at a temperature of 1000°C.

[0009] Another objective is to suppress the spread of flame from the battery pack and between the battery cells within the battery pack at a temperature of 1000°C for 10 minutes.

[0010] Another object of this disclosure is to provide a heat insulation for use with electric vehicle battery packs that at least addresses the need to provide dielectric protection to the battery pack and between the battery cells of the battery pack.

[0011] Another object of this disclosure is to provide a heat insulation for use with electric vehicle battery packs that is flexible to promote conformability of the heat insulation around the battery pack and between the battery cells of the battery pack.

[0012] Another object of this disclosure is to facilitate the easy installation of thermal insulation around the battery pack and between the battery cells of the battery pack.

[0013] Another object of this disclosure is to provide a heat insulation for electric vehicle battery packs that is lightweight, has a low profile to minimize the space occupied by the heat insulation, and is economical to manufacture and use.

[0014] One aspect of the present invention provides a heat insulation for a battery pack of an electric vehicle, the heat insulation having a wall comprising a loosely woven polyether ether ketone (PEEK) layer, a first pressure-sensitive adhesive layer coated on one side of the loosely woven PEEK layer, and a silica fabric bonded to the pressure-sensitive adhesive.

[0015] According to another aspect of the invention, the second pressure-sensitive adhesive layer can be bonded to the silica fabric to facilitate fixing the insulation in the desired position.

[0016] According to another aspect of the invention, the release film can be peelably fixed to a second pressure-sensitive adhesive layer, wherein the release film is configured to be removed to expose the underlying second pressure-sensitive adhesive layer for fixing to the surface and / or housing of an electric vehicle battery pack.

[0017] According to another aspect of the invention, the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer may be provided as an acrylic pressure-sensitive adhesive.

[0018] According to another aspect of the invention, the wall prevents flame propagation when exposed to 1000°C for 10 minutes.

[0019] According to another aspect of the invention, the wall has an insulation resistance of 4000 Mohm or greater before and after exposure to 1000°C for 10 minutes.

[0020] According to another aspect of the invention, the maximum wall thickness is 5 mm, thereby having a low profile to enhance the design and reduce weight.

[0021] According to another aspect of the invention, the maximum thickness of the wall is 2 mm, thereby having a minimized profile to enhance the design and minimize weight.

[0022] According to another aspect of the invention, the wall has a dielectric strength of 2 kV after being exposed to 1000°C for 10 minutes.

[0023] According to another aspect of the invention, a flexible thermal insulation material for an electric vehicle battery pack has a composite wall comprising a silica fabric sheet having opposing first and second sides, and a first pressure-sensitive adhesive layer bonded to the first side of the silica fabric sheet.

[0024] According to another aspect of the invention, a flexible thermal insulation material for an electric vehicle battery pack is provided, having a composite wall comprising a flame-retardant material sheet having opposing first and second sides. A first pressure-sensitive adhesive layer is bonded to the first side of the flame-retardant material sheet. Furthermore, a loosely woven, polyetheretherketone (PEEK) reinforced layer is bonded to the second side of the flame-retardant material, or a silicone rubber layer is bonded to the second side of the flame-retardant material.

[0025] According to another aspect of the invention, the second pressure-sensitive adhesive layer may be bonded to a loosely woven polyetheretherketone (PEEK) layer.

[0026] According to another aspect of the invention, the release film can be peelably fixed to a first pressure-sensitive adhesive layer, wherein the release film is configured to be removed to expose the underlying first pressure-sensitive adhesive layer for fixing to the surface and / or housing of an electric vehicle battery pack.

[0027] According to another aspect of the invention, the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer may be provided as an acrylic pressure-sensitive adhesive.

[0028] According to another aspect of the invention, the composite wall prevents flame propagation when exposed to 1000°C for 10 minutes.

[0029] According to another aspect of the invention, the composite wall has an insulation resistance of 4000 Mohm or greater before and after exposure to 1000°C for 10 minutes.

[0030] According to another aspect of the invention, the composite wall has a maximum thickness of 5 mm.

[0031] According to another aspect of the invention, the composite wall has a maximum thickness of 2 mm.

[0032] According to another aspect of the invention, the composite wall has a dielectric strength of 2 kV after being exposed to 1000°C for 10 minutes.

[0033] According to another aspect of the invention, the composite wall of the flexible insulation includes a silicone layer bonded to a second side of a silica fabric sheet.

[0034] According to another aspect of the present invention, an electric vehicle battery pack is provided. The electric vehicle battery pack includes a housing defining a plurality of battery cells. Furthermore, a composite wall covers the plurality of battery cells. The composite wall includes: a silica fabric sheet having opposing first and second sides, and a first pressure-sensitive adhesive layer bonded to the first side of the silica fabric sheet.

[0035] According to another aspect of the invention, the electric vehicle battery pack may further include a second pressure-sensitive adhesive layer bonded to a loosely woven polyether ether ketone (PEEK) layer.

[0036] According to another aspect of the invention, the electric vehicle battery pack may further include a release film peelably attached to a first pressure-sensitive adhesive layer, the release film being configured to be removed to expose the underlying first pressure-sensitive adhesive layer for operably attaching to the surface of the housing.

[0037] According to another aspect of the invention, the first and second pressure-sensitive adhesive layers of the electric vehicle battery pack can be provided as acrylic pressure-sensitive adhesives.

[0038] According to another aspect of the invention, the composite wall of the electric vehicle battery pack prevents flame propagation when exposed to 1000°C for 10 minutes.

[0039] According to another aspect of the invention, the composite wall of the electric vehicle battery pack has an insulation resistance of 4000 Mohm or greater before and after exposure to 1000°C for 10 minutes.

[0040] According to another aspect of the invention, the maximum thickness of the composite wall of the electric vehicle battery pack is 5 mm.

[0041] According to another aspect of the invention, the maximum thickness of the composite wall of the electric vehicle battery pack is 2 mm.

[0042] According to another aspect of the invention, the composite wall of the electric vehicle battery pack has a dielectric strength of 2kV after being exposed to 1000°C for 10 minutes.

[0043] According to another aspect of the invention, the composite wall of the electric vehicle battery pack further includes a silicone layer bonded to a second side of a flame-retardant material sheet, wherein the flame-retardant material is a silica fabric.

[0044] According to another aspect of the invention, the silica fabric is woven from silica multifilament yarn. Attached Figure Description

[0045] These and other aspects, features, and advantages will become apparent to those skilled in the art from the following detailed description of the present preferred embodiments and best modes, the appended claims, and the accompanying drawings, wherein:

[0046] Figure 1 It is a schematic perspective view of an electric vehicle having a battery pack having a plurality of heat insulation elements constructed according to one aspect of the invention;

[0047] Figures 2A-2C A schematic diagram of multiple battery cells in an electric vehicle battery pack is shown, which do not have the thermal insulation according to the invention. These battery cells are experiencing thermal runaway, wherein the flame originates from the ignition point ( Figure 2A ) propagates unimpeded throughout the entire battery pack ( Figure 2C );

[0048] Figures 3A-3C It is similar to Figures 2A-2C The view shows the battery pack including multiple heat insulators, with the heat insulators shown suppressing and blocking flames from thermal runaway conditions. Figure 3A ) propagates throughout the entire battery pack ( Figure 3C );

[0049] Figure 4 This is a schematic perspective view of a heat insulation body according to an embodiment of the present disclosure;

[0050] Figure 4A It shows including Figure 4 A graph showing the surface temperature of the battery pack's outer casing, where the battery pack was exposed to 1000°C for 10 minutes.

[0051] Figure 5 This is a schematic perspective view of a heat insulation body according to another embodiment of the present disclosure; and

[0052] Figure 5A It shows including Figure 5 A graph showing the surface temperature of the battery pack's outer casing, where the battery pack was exposed to 1000°C for 10 minutes. Detailed Implementation

[0053] Please refer to the attached diagram for more details. Figure 1 A motor vehicle, shown as an electric motor vehicle, also referred to as an electric vehicle 11, is illustrated, having a battery pack 12, such as a lithium-ion battery pack, configured with at least one (shown as multiple) heat insulator 10 according to one aspect of the invention. The electric vehicle battery pack 12 includes a housing 14 comprising a plurality of battery modules 15, each battery module 15 defining a plurality of battery cells 16. During normal use, and including under abnormal conditions (e.g., in the event of a vehicle collision or when some other condition exerts an impact on the battery pack 12), thermal runaway conditions originating from any one of the battery cells 16 are controlled and suppressed by the heat insulator 10, such that the propagation (spread) of flame between the battery cells 16 and from the battery pack 12 outwards is prevented for at least 10 minutes, and the outer surface temperature of the battery housing 14 (also referred to as the casing) is maintained below 500°C, as confirmed by a test conducted at 1000°C for 10 minutes. Figure 4A The outer surface temperature 17 of a first embodiment of a heat insulation body 10 constructed according to one aspect of this disclosure is shown after being exposed to a temperature of 1000°C as shown in 19 for 10 minutes. Figure 5A The outer surface temperature 117 of a second embodiment of a heat insulation 110 constructed according to another aspect of this disclosure is shown, which is exposed to a temperature of 1000°C as shown in 119 for 10 minutes (where different heat insulations 10, 100 will be discussed in further detail below).

[0054] like Figure 4 As schematically shown, the insulation 10 comprises a generally flat composite sheet (also referred to as a composite wall, laminated wall, or wall 18) that covers a plurality of battery cells 16 and extends between the battery cells 16 to effectively isolate each battery cell 16 from adjacent battery cells 16. The composite wall 18 comprises an insulating fabric sheet 20 having opposing first sides 22 and second sides 24. The insulating fabric 20 is formed of a flame-retardant material, such as tightly woven flame-retardant filaments (also referred to as multifilament yarns), and in a preferred embodiment, the insulating fabric 20 is formed entirely of tightly interwoven silica multifilament yarns 25, wherein the multifilament yarns 25 are preferably woven using a tightly plain weave pattern to achieve maximum density. Furthermore, a first pressure-sensitive adhesive layer 26 may be bonded to the first side 22 of the silica fabric sheet 20 to facilitate securing the composite wall 18 to desired surfaces of the battery pack 12, including between adjacent battery cells 16 and / or around the inner and / or outer surfaces of the housing 14. In addition, a silicone rubber layer 28 is coated or otherwise bonded to the second side 24 of the silica fabric sheet 20. The silicone rubber layer 28 is a fluid-impermeable layer, thereby enhancing protection against contaminant ingress and significantly improving the flame-retardant properties of the wall 18, thereby further suppressing the spread of flame between adjacent battery cells 16 and outward, thus extending the service life of the battery pack 12 during emergency situations.

[0055] According to another aspect of the invention, as an alternative to the silicone rubber layer 28 (as discussed above with respect to the heat insulation 10), the composite wall 118 of the heat insulation 110 of the electric vehicle battery pack 12 (as...) Figure 5 (As shown) It also includes a second pressure-sensitive adhesive layer 30 bonded to the second side 24 of the woven sheet of silica fabric 20, and a loosely woven polyetheretherketone layer 32 bonded to the second pressure-sensitive adhesive layer 30, such that the second pressure-sensitive adhesive layer 30 is sandwiched between the second side 24 of the silica fabric sheet 20 and the loosely woven polyetheretherketone layer 32.

[0056] According to another aspect of the invention, the electric vehicle battery pack may further include a release film 34 peelably attached to a first pressure-sensitive adhesive layer 26, wherein the release film 34 is configured to be removed to expose the underlying first pressure-sensitive adhesive layer 26 for operative attachment to the surfaces of the respective battery cell 16 and the housing 14.

[0057] According to another aspect of the invention, the first pressure-sensitive adhesive layer 26 and the second pressure-sensitive adhesive layer 30 of the electric vehicle battery pack 12 may be provided as an acrylic pressure-sensitive adhesive.

[0058] According to another aspect of the invention, the composite walls 18, 118 of the electric vehicle battery pack 12 prevent flame propagation when exposed to 1000°C for 10 minutes.

[0059] According to another aspect of the invention, the composite walls 18, 118 of the electric vehicle battery pack 12 have an insulation resistance of 4000 Mohm or greater before and after exposure to 1000°C for 10 minutes.

[0060] According to another aspect of the invention, the composite walls 18, 118 of the electric vehicle battery pack 12 have a maximum thickness (t) of 5 mm.

[0061] According to another aspect of the invention, the composite walls 18, 118 of the electric vehicle battery pack 12 have a maximum thickness (t) of 2 mm.

[0062] According to another aspect of the invention, the composite walls 18, 118 of the electric vehicle battery pack 12 have a dielectric strength of 2 kV after being exposed to 1000°C for 10 minutes.

[0063] Clearly, based on the foregoing teachings, the present invention can be modified and varied in many ways. It is contemplated that all features of all claims and all embodiments can be combined with each other, provided that such combinations do not contradict each other. Therefore, it should be understood that the invention can be practiced in ways other than those specifically described within the scope of the appended claims.

Claims

1. A flexible thermal barrier for an electric vehicle battery pack, the electric vehicle battery pack comprising a housing, the housing comprising a plurality of battery modules, each of the battery modules defining a plurality of battery cells, the flexible thermal barrier comprising: a composite wall covering and extending between the plurality of battery cells to isolate each battery cell from an adjacent battery cell, the composite wall comprising: a sheet of flame resistant material having opposing first and second sides; a first layer of pressure sensitive adhesive bonded to the first side of the sheet of flame resistant material; and one of a scrim reinforced polyether ether ketone layer bonded to the second side of the sheet of flame resistant material or a silicone rubber layer bonded to the second side of the sheet of flame resistant material, wherein the sheet of flame resistant material is formed entirely of tightly interwoven silica multifilament yarns, wherein the multifilament yarns are woven using a tight plain weave pattern to achieve maximum density.

2. The flexible thermal barrier of claim 1, further comprising a second layer of pressure sensitive adhesive bonded to the scrim reinforced polyether ether ketone layer.

3. The flexible thermal barrier of claim 2, further comprising a release film releasably secured to the second layer of pressure sensitive adhesive, wherein the release film is configured to be removed to expose the underlying second layer of pressure sensitive adhesive for securing to a surface of the electric vehicle battery pack.

4. The flexible thermal barrier of claim 3, wherein the first and second layers of pressure sensitive adhesive are acrylic pressure sensitive adhesives.

5. The flexible thermal barrier of claim 1, wherein the composite wall prevents flame propagation when exposed to 1000°C for 10 minutes.

6. The flexible thermal barrier of claim 1, wherein the composite wall has an insulation resistance of 4000 Mohm or greater before and after exposure to 1000°C for 10 minutes.

7. The flexible thermal barrier of claim 1, wherein the composite wall has a maximum thickness of 5 mm.

8. The flexible thermal barrier of claim 7, wherein the composite wall has a maximum thickness of 2 mm.

9. The flexible thermal barrier of claim 1, wherein the composite wall has a dielectric strength of 2 kV after exposure to 1000°C for 10 minutes.

10. An electric vehicle battery pack comprising: a housing; a plurality of battery cells defined by the housing; and a plurality of composite walls, each of the composite walls covering a plurality of battery cells and extending between the plurality of batteries, and comprising: a sheet of flame resistant material having opposing first and second sides; a first layer of pressure sensitive adhesive bonded to the first side of the sheet of flame resistant material; and one of a scrim reinforced polyether ether ketone layer bonded to the second side of the sheet of flame resistant material or a silicone rubber layer bonded to the second side of the sheet of flame resistant material, wherein at least some of the composite walls separate adjacent ones of the battery cells from one another; wherein the sheet of flame resistant material is formed entirely of tightly interwoven silica multifilament yarns, wherein the multifilament yarns are woven using a tight plain weave pattern to achieve maximum density. ​ 11. The electric vehicle battery pack of claim 10, wherein at least part of the composite wall comprises a second pressure sensitive adhesive layer bonded to a polyether ether ketone layer reinforced with the scrim.

12. The electric vehicle battery pack of claim 11, further comprising a release film releasably secured to the first pressure sensitive adhesive layer, the release film configured to be removed to expose the underlying first pressure sensitive adhesive layer for operable securement to a surface of the housing.

13. The electric vehicle battery pack of claim 12, wherein the first and second pressure sensitive adhesive layers are acrylic pressure sensitive adhesives.

14. The electric vehicle battery pack of claim 10, wherein the composite wall prevents flame propagation when exposed to 1000°C for 10 minutes.

15. The electric vehicle battery pack of claim 10, wherein the composite wall has an insulation resistance of 4000 Mohm or greater before and after exposure to 1000°C for 10 minutes.

16. The electric vehicle battery pack of claim 15, wherein the composite wall has a maximum thickness of 2 mm.

17. The electric vehicle battery pack of claim 10, wherein the composite wall has a dielectric strength of 2 kV after exposure to 1000°C for 10 minutes.

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