Multilayer battery separator and method of making same

Abstract

A flexible multi-layer battery pack insulator for an electric vehicle includes a first layer of coated material having opposite outer and inner sides, a second layer of compressible material having opposite outer and inner sides, and an intermediate fabric layer sandwiched between the inner side of the first layer and the inner side of the second layer, wherein the second layer has a relaxed thickness extending from the inner side to the outer side thereof, and the second layer is capable of compressing the relaxed thickness by up to 50% and recovering to the relaxed thickness.

Description

Technical Field

[0001] Cross-reference to related applications This application claims priority to U.S. Provisional Application No. 63 / 558,467, filed February 27, 2024, and to U.S. Application No. 19 / 063,014, filed February 25, 2025, the entire contents of which are incorporated herein by reference.

[0002] The present invention relates generally to heat insulation materials, and more specifically to multi-layer heat insulation materials for suppressing the propagation of flames inside and from an electric vehicle battery pack. Background Technology

[0003] The known practice is to house or shield battery packs (including those used in electric vehicle applications) within insulation. A common material used to form such insulation is fiberglass fabric. While fiberglass fabric insulation provides an acceptable level of protection against contaminants and ambient temperatures during normal use, it fails to provide an ideal level of protection against flame propagation when one or more battery cells in an electric vehicle battery pack experience thermal runaway. As shown in Figures 2A-2C, the battery pack 12 and its housing 14 (also referred to as the casing) have fiberglass insulation between and around the battery cells 16 of the battery pack 12. This fiberglass insulation could cause thermal runaway in any one of the battery cells 16 in the battery pack 12, allowing a flame to propagate from a single battery cell 16 (Figure 2A) to multiple battery cells (Figure 2C) within 10 minutes at a temperature of 1000°C.

[0004] It is desirable to provide a heat insulation that, when exposed to a flame at a temperature of 1000°C to 1400°C at a distance of approximately 25 mm from the battery pack, can inhibit the spread of flame between the battery cells of the battery pack for 10 minutes or longer. Summary of the Invention

[0005] One object of this disclosure is to provide a flexible multilayer material for electric vehicle battery packs that can at least meet the requirement of suppressing flame propagation inside and out of the battery pack for 10 minutes or longer at a temperature of 1000–1400°C.

[0006] Another object of this disclosure is to provide a flexible multilayer material for electric vehicle battery packs, which is flexible, lightweight, thin and low profile (thickness) to minimize the space occupied by the insulation, and is cost-effective in both manufacture and use.

[0007] One aspect of the present invention provides a flexible multilayer battery pack insulation for electric vehicles. The flexible multilayer battery pack insulation includes a first layer as a coating layer, a second layer as a compressible material, and an intermediate layer sandwiched between the first and second layers.

[0008] According to another aspect of the invention, the intermediate layer is a fabric layer.

[0009] According to another aspect of the invention, the flexible multilayer battery pack insulation may further include an adhesive layer bonded to the outer surface of at least one of the first and second layers.

[0010] According to another aspect of the invention, the adhesive layer may be a pressure-sensitive adhesive layer.

[0011] According to another aspect of the invention, the coating material of the first layer comprises a flame-retardant / flame-suppressing material.

[0012] According to another aspect of the invention, the coating material of the first layer can withstand high temperatures up to 1600°C.

[0013] According to another aspect of the invention, the coating material of the first layer may contain vermiculite in part or in whole.

[0014] According to another aspect of the invention, the coating material of the first layer may comprise an intumescent material.

[0015] According to another aspect of the invention, the second compressible material may be a compression pad, a 3D textile, a spacer fabric having multiple layers of textile fabric, or a foam.

[0016] According to another aspect of the invention, the second compressible material provides a compressive force-deformation curve that results in significant compression and recovery properties relative to the percentage of relaxation thickness over the width of the second layer extending from one side to the other.

[0017] According to another aspect of the invention, the second compressible material can be designed to compress up to 90% of its relaxation thickness and recover to its original relaxation thickness after compression.

[0018] According to another aspect of the invention, the intermediate layer may be one or more of a nonwoven material, a woven material, or a knitted material.

[0019] According to another aspect of the invention, if the intermediate layer is a nonwoven material, it may be made of mineral fibers; if it is a woven or knitted material, it may be made of mineral yarns.

[0020] According to another aspect of the invention, the intermediate layer may be made of inorganic materials.

[0021] According to another aspect of the invention, the inorganic material may be made of one or more of ceramic materials, glass fibers, silica, basalt, S-2 glass and HR glass fibers.

[0022] According to another aspect of the invention, the first layer, the second layer, and the intermediate layer are fixed together.

[0023] According to another aspect of the invention, the first layer, the second layer, and the intermediate layer can be fixed together by sewing or quilting.

[0024] According to another aspect of the invention, the first layer, the second layer and the intermediate layer can remain separate from each other except at the points where they are fixed together, thereby forming air cavities between the layers.

[0025] According to another aspect of the invention, the first layer, the second layer, and the intermediate layer can be fixed together by an adhesive.

[0026] According to another aspect of the invention, the combined thickness of the first layer, the second layer and the intermediate layer is between about 0.1 mm and 11 mm.

[0027] According to another aspect of the present invention, a method for manufacturing a flexible multilayer battery pack insulation is provided. The method includes: providing a compressible material layer; providing a fabric layer; directly fixing a coating layer onto the fabric layer and directly fixing the compressible material layer onto the fabric layer, such that the fabric layer is sandwiched between the coating layer and the compressible material layer.

[0028] According to another aspect of the invention, the method may further include maintaining the compressible material layer and the fabric layer in a separate relationship, except in the position where they are fixed together.

[0029] According to another aspect of the invention, the method may further include securing the compressible material layer to the fabric layer by sewing or quilting.

[0030] According to another aspect of the invention, the method may further include making a fabric layer from one or more of nonwoven materials, woven materials and knitted materials.

[0031] According to another aspect of the invention, the method may further include a fabric layer made of mineral fibers and / or mineral yarns.

[0032] According to another aspect of the invention, the intermediate layer may be made of inorganic materials.

[0033] According to another aspect of the invention, the method may further include selecting one or more inorganic materials selected from ceramic materials, glass fibers, silica, basalt, S-2 glass and HR glass fibers.

[0034] According to another aspect of the invention, the method may further include providing a compressible material layer, which is a compression pad, a three-dimensional textile, a spacer fabric having multiple layers of textile fabric, or a foam.

[0035] According to another aspect of the invention, the method may further include providing a compressible material layer having a compressive force-deformation curve that enables significant compression and resilience properties relative to the percentage of relaxation thickness of the second layer in the width direction extending from one side to the other.

[0036] According to another aspect of the invention, the method may further include providing a compressible material layer such that the compressible material can compress up to 90% of its relaxation thickness and recover to its original relaxation thickness after compression.

[0037] According to another aspect of the invention, the method may further include bonding an adhesive to the outer surface of at least one of the compressible material layer and the coating layer. Attached Figure Description

[0038] Those skilled in the art will readily understand these and other aspects, features, and advantages by reading the following detailed description of the presently preferred embodiments and best practices, the appended claims, and the accompanying drawings, wherein: Figure 1 It is a schematic perspective view of an electric vehicle with a battery pack having a multilayer heat insulation structure constructed according to one aspect of the invention; Figures 2A-2C schematically illustrate the state of an electric vehicle battery pack in the event of thermal runaway, where flames propagate unimpeded from the ignition point (Figure 2A) to multiple battery cells in the battery pack (Figure 2C). Figures 3A-3C Similar to Figures 2A-2C, the electric vehicle battery pack includes one or more flexible multilayer battery pack insulations constructed according to one aspect of this disclosure, wherein the flexible multilayer battery pack insulations shown are capable of suppressing and preventing flames from thermal runaway locations within individual battery cells. Figure 3A ) propagates to multiple battery cells in the battery pack ( Figure 3C ); Figure 4A This is a schematic plan view of one of the flexible multilayer battery pack insulation components; Figure 4B It is roughly along Figure 4A A cross-sectional view taken from line 4B-4B in the middle; Figure 5 It is roughly along Figure 4A A cross-sectional view of the area shown by line 5-5 in the middle; Figure 6A and Figure 4ASimilarly, this is a view of a flexible multilayer battery pack insulation constructed according to another aspect of this disclosure, showing the layers stitched together by a quilting process; Figure 6B It is roughly along Figure 6A A cross-sectional view taken from line 6B-6B in the middle; Figure 7A yes Figure 5 A partial side view of one of the layers in a relaxed, uncompressed state; Figure 7B Is with Figure 7A A similar view shows the shape of the layer when it is compressed; and Figure 8 yes Figure 7A and Figure 7B The compression curve of the layer shown is shown. Detailed Implementation

[0039] Further details are provided in conjunction with the accompanying drawings. Figure 1 A motor vehicle, an electric motor vehicle (also known as an electric vehicle EV), is shown equipped with a battery pack 12 (e.g., a lithium-ion battery pack). According to one aspect of the invention, the battery pack is configured with at least one heat insulator, shown as multiple heat insulators, also referred to as flexible multilayer battery pack insulators or heat insulators 10. The electric vehicle battery pack 12 includes a housing component (also referred to as a housing or casing 14) that surrounds multiple battery cells 16 and optionally includes one or more busbars for electrically connecting the battery cells to each other, high-voltage electrical connectors, battery cell interfaces, low-voltage signal lines, high-voltage cables, and a cooling system with cooling pipes (through which coolant can flow), as is well known in electric vehicle battery packs. During normal use, and in other situations including abnormal or unusual conditions, such as vehicle collisions or other situations causing damage to or impact to the battery pack 12, compared to a battery pack 12 without the heat insulator 10 disclosed in this invention, as shown in Figures 2A-2C, such as… Figures 3A-3C As shown, since the flexible heat insulation 10 is arranged between and / or around the battery cells 16, the thermal runaway of any battery cell 16 in the battery pack 12 will be controlled and confined to the battery cell that generates overheating and / or flame by the flexible heat insulation 10. Thus, when the internal temperature of the battery cell is between 1200-1400°C, the flame can be prevented from spreading from the battery cell that generates overheating and / or flame to the adjacent battery cell 16 for at least 10 minutes, and the outer surface temperature of the outer casing 14 can be maintained below 200°C, preferably 150°C, for at least 10 minutes.

[0040] like Figures 3A-3CAs shown, the heat insulation 10 can be arranged between adjacent battery cells 16 to achieve thermal separation and thermal isolation between the battery cells 16; it can also be arranged around at least a portion of the battery pack housing 14 to provide thermal shielding and protection for the surface of the battery pack housing 14, the aforementioned busbars, high-voltage electrical connectors, battery cell interfaces, low-voltage signal lines, high-voltage cables, and any cooling pipes (not shown), protecting them from extreme temperature thermal runaway, preventing contaminants from fluids or debris, and resisting impact forces, such as those encountered in a collision. The heat insulation 10 is provided in the form of a relatively thin, flexible multilayer wall 18, with a thickness as low as 0.1 mm and as high as about 11 mm, preferably between about 1 mm and 2 mm. Because the wall 18 is thin and flexible, it can be configured and shaped as needed. For example, it can be wound into a hollow tubular sleeve structure to wrap busbars, wires, pipes, connectors, etc. It can also be in sheet form, such as a flat planar sheet, to provide a protective external barrier around the battery cell 16 and a protective barrier between adjacent battery cells 16, thereby effectively thermally isolating each battery cell 16 from its adjacent battery cells 16.

[0041] like Figure 5 As shown in the schematic cross-sectional view, the composite wall 18 includes a first layer 20 disposed as a coating layer, the first layer 20 having opposing outer sides 20a and inner sides 20b. The composite wall 18 also includes a second layer 22 disposed as a compressible material, the second layer 22 having opposing outer sides 22a and inner sides 22b. Furthermore, the composite wall 18 includes an intermediate layer 24 disposed as a fabric layer, wherein the fabric layer 24 is sandwiched, also referred to as being trapped, between the inner side 20b of the first layer 20 and the inner side 22b of the second layer 22. It should be noted that the term "inner side" (referring to the inner sides 20b, 22b) is intended to identify those sides facing inward toward the intermediate layer 24.

[0042] To facilitate positioning and securing the heat insulation 10, at least one layer (shown as a pair in the figure) of adhesive layers 26a, 26b may be secured (e.g., by bonding) to the respective outer side 20a of the first layer 20 and the outer side 22a of the second layer 22, if desired. The adhesive layers 26a, 26b may be designed as pressure-sensitive adhesive layers 26a, 26b with flame-retardant properties; in a preferred embodiment, an acrylic adhesive may be used. Release layers 28a, 28b may be peelably bonded to the outer side (i.e., the side away from the intermediate layer 24) of the pressure-sensitive adhesive layers 26a, 26b so that when it is necessary to bond the pressure-sensitive adhesive layers 26a, 26b (if provided) to a designated surface of the electric vehicle battery pack 12, they can be selectively peeled off to expose the underlying pressure-sensitive adhesive layers 26a, 26b. The pressure-sensitive adhesive layers 26a, 26b according to this disclosure, if provided, provide a minimum peel strength of not less than 5 N / 25 mm under normal operating conditions.

[0043] The coating material of the first layer 20 contains at least one flame-retardant / flame-inhibiting material. The coating material of the first layer 20 can withstand high temperatures up to 1600°C. The coating material of the first layer 20 may contain an intumescent material and may contain vermiculite in part or in whole.

[0044] The intermediate layer 24 may include one or more of nonwoven materials, woven materials, and / or knitted materials. The intermediate layer 24 may be made of mineral fibers and / or mineral yarns. The intermediate layer 24 may be made of inorganic materials, wherein the inorganic materials may include one or more of ceramic materials, glass fibers, silica, basalt, S-2 glass, and HR glass fibers, including their intertwined fibers (nonwoven) or their interwoven (woven or knitted) multifilament yarns.

[0045] The compressible material of the second layer 22 can be a compression pad, a three-dimensional textile, a spacer fabric with interconnected multi-layered textile fabrics, or a foam. The compressible material of the second layer 22 provides a compressive force-deformation curve ( Figure 8 This curve shows significant compression and recovery properties relative to the percentage of uncompressed, relaxed thickness over the width (also known as thickness) of the second layer 22 from one side to the other, where, for example Figure 7A and 7B As shown, the compressible material 22 can be designed from its relaxed, uncompressed thickness t1 ( Figure 7A ) compressed to a compression thickness t2 ( Figure 7B The compression range can reach 25%, preferably 50%, and more preferably 90%, and it can immediately recover to its original relaxation thickness t1 after compression. Therefore, the second layer 22 allows the battery cells 16 to move laterally relative to each other, so that adjacent battery cells 16 can move closer or further away from each other without generating internal stress within each individual battery cell 16, thereby avoiding damage to adjacent battery cells 16 during periodic thermal events.

[0046] The first layer 20, the second layer 22, and the middle layer 24 are fixed together by a sewing process (e.g., sewing). Figure 4A and 4B ) or quilting ( Figure 6A and 6B The process involves fixing them together; this is merely an example and not a limitation. For example... Figure 4A and 4BAs shown, the first outer membrane layer 20, the second outer layer 22, and the intermediate fabric layer 24 each have outer perimeters 30a, 30b, and 30c, and can be fixed together by at least one thread (also referred to as yarn or filament 32) during sewing and quilting processes. The thread 32 extends adjacent to the outer perimeters 30a, 30b, and 30c as shown in the figure (this is just an example and is not limited to this), and is shown to extend closely to and through the outer perimeters 30a, 30b, and 30c, thereby sealing the outer perimeters 30a, 30b, and 30c to prevent water or debris from seeping in, while also serving to fix the layers 20, 22, and 24 together. The first outer membrane layer 20, the second outer layer 22, and the intermediate fabric layer 24 can remain largely separate from each other inside the seam 32, thereby allowing an air layer or air gap 34 to be retained or formed between the individual layers 20, 22, and 24, thus improving the thermal insulation performance of the insulation body 10. It should be noted that, if necessary, in the quilting process (… Figure 6A and 6B The stitches 32 formed in the process may include multiple stitches arranged in any desired pattern, spaced apart from each other to form multiple air gaps, also known as air cavities or air layers 34.

[0047] According to another aspect of the present invention, a method for manufacturing a heat-insulating material 10 for an electric vehicle battery pack 12 is provided. The method includes providing a first layer 20 as a coating layer having opposing outer sides 20a and inner sides 20b; providing a second layer 22 as a compressible material having opposing outer sides 22a and 22b; and an intermediate layer 24 as a fabric layer sandwiched between the inner sides 20b of the first layer 20 and the inner sides 22b of the second layer 22; and fixing the first layer 20, the second layer 22, and the intermediate layer 24 to each other.

[0048] According to another aspect of this disclosure, the method may further include securing at least some of the layers 20, 22, 24 together by at least one suture 32.

[0049] According to another aspect of this disclosure, the method may also include keeping the first layer 20, the second layer 22 and the intermediate layer 24 separated from each other except in a fixed position together.

[0050] According to another aspect of this disclosure, the method may further include forming at least one suture 32 along the opposite outer peripheries 30a, 30b, 30c of the first layer 20, the second film layer 22 and the intermediate layer 24.

[0051] According to another aspect of this disclosure, the method may further include fixing layers 20, 22, and 24 to each other by a quilting process. Figure 6A and 6BThis creates an air cavity 34 between layers 20, 22, and 24, which is formed by the stitches 32 of the quilted layers 20, 22, and 24.

[0052] According to another aspect of this disclosure, the method may further include forming the first layer 20 into a coating comprising at least one flame-retardant / flame-suppressing material.

[0053] According to another aspect of this disclosure, the method may further include providing a coating layer 20 capable of withstanding temperatures up to 1600°C.

[0054] According to another aspect of this disclosure, the method may also include providing a coating layer 20, which comprises vermiculite in part or all of its contents.

[0055] According to another aspect of this disclosure, the method may also include providing an intermediate layer 24 made of one of a nonwoven material, a woven material, or a knitted material.

[0056] According to another aspect of this disclosure, the method may further include providing an intermediate layer 24 made of interwoven mineral fibers and / or interwoven mineral yarns.

[0057] According to another aspect of this disclosure, the method may further include providing an intermediate layer 24 made of an inorganic material, wherein the inorganic material may include one or more of ceramic materials, glass fibers, silica, basalt, S-2 glass, and HR glass fibers.

[0058] According to another aspect of this disclosure, the method may further include providing a second layer 22 made of one of a compression pad, a 3D textile, a spacer fabric having multiple interconnected textile fabrics, or a foam.

[0059] According to another aspect of this disclosure, the method may further include providing a second layer 22 of compressible material having a compressive force-deformation curve (…). Figure 8 This curve indicates that the material achieves significant compression and full recovery properties relative to the percentage of relaxation thickness over the width of the second layer 22 extending from one side to the other; where, for example... Figure 7A and 7B As shown, the compressible material 22 can be configured to compress up to 90% of its relaxation thickness t1. Figure 7A ) to the compression thickness t2 ( Figure 7B ), and immediately recovers to its original relaxed thickness t1 after compression.

[0060] According to another aspect of this disclosure, the method may further include applying a coating layer 20 to the intermediate layer 24 after securing the intermediate layer 24 to the compressible second layer 22.

[0061] According to another aspect of this disclosure, the method may further include applying a coating layer 20 to the intermediate layer 24 before securing the intermediate layer 24 to the compressible second layer 22.

[0062] According to another aspect of this disclosure, the method may further include bonding at least one or a pair of adhesive layers 26a, 26b to respective outer sides 20a of the first layer 20 and outer sides 22a of the second layer 22.

[0063] Clearly, based on the above teachings, the present invention can be modified and varied in many ways. The present invention contemplates 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 within the scope of the appended claims, the invention can be practiced in ways different from those specifically described.

Claims

1. A flexible multilayer battery pack thermal insulation for electric vehicles, comprising: A first layer made of a coating material, the first layer having opposing outer and inner sides; A second layer made of compressible material, the second layer having opposing outer and inner sides; and An intermediate fabric layer sandwiched between the inner side of the first layer and the inner side of the second layer. The second layer has a relaxation thickness that extends from the inner side of the second layer to the opposite outer side, and wherein the second layer is capable of compressing the relaxation thickness by up to 50% and then restoring it to the relaxation thickness.

2. The flexible multilayer battery pack heat insulation material as described in claim 1, wherein, The second layer is capable of compressing up to 90% of the relaxation thickness and restoring it to the relaxation thickness.

3. The flexible multilayer battery pack thermal insulation as claimed in claim 1, wherein the first layer comprises at least one layer capable of withstanding temperatures up to 1600°C. o Flame-retardant / flame-suppressing materials at temperature C.

4. The flexible multilayer battery pack insulation as claimed in claim 3, wherein the first layer comprises vermiculite.

5. The flexible multilayer battery pack thermal insulation as described in claim 1, wherein the first layer is an expandable material.

6. The flexible multilayer battery pack insulation as described in claim 1, wherein the intermediate fabric layer is one of a nonwoven material, a woven material, or a knitted material.

7. The flexible multilayer battery pack heat insulation as described in claim 6, wherein, The intermediate fabric layer is made of mineral fibers and / or mineral yarns.

8. The flexible multilayer battery pack heat insulation material as described in claim 7, wherein, The intermediate fabric layer is made of one or more of the following materials: ceramic, glass fiber, silica, basalt, S-2 glass, and HR glass fiber.

9. The flexible multilayer battery pack insulation as claimed in claim 1, wherein the first layer, the second layer and the intermediate fabric layer are fixed together by stitching.

10. The flexible multilayer battery pack insulation as claimed in claim 9, wherein at least one air cavity is formed between the seams.

11. The flexible multilayer battery pack insulation of claim 9, wherein the first layer and the intermediate fabric layer, or the second layer and the intermediate fabric layer, are fixed together by an adhesive.

12. The flexible multilayer battery pack insulation of claim 1, wherein the first layer, the intermediate fabric layer and the second layer are fixed together by an adhesive.

13. The flexible multilayer battery pack insulation as claimed in claim 1, further comprising an adhesive layer bonded to at least one outer surface of the first layer and the second layer.

14. The flexible multilayer battery pack insulation of claim 13, further comprising a release layer peelably bonded to the adhesive layer.

15. The flexible multilayer battery pack insulation as claimed in claim 1, wherein the second layer of compressible material is one of a compression pad, a 3D textile, a spacer fabric having multiple layers of textile fabric, or a foam.

16. A method for manufacturing a flexible multilayer battery pack heat insulation material, comprising: A first layer made of a coating material is provided, the first layer having a first outer side and an opposing first inner side; A second layer made of a compressible material is provided, the second layer having a second layer outer side and an opposing second layer inner side, and having a relaxation thickness extending between the second layer inner side and the second layer outer side, wherein the second layer is capable of compressing the relaxation thickness by up to 50% and returning to the relaxation thickness; and An intermediate layer made of fabric material is sandwiched between the inner side of the first layer and the inner side of the second layer.

17. The method of claim 16, wherein, This relaxation thickness can be compressed up to 90% and then restored to that relaxation thickness.

18. The method of claim 16, further comprising providing a first layer comprising vermiculite.

19. The method of claim 16, further comprising providing a first layer comprising an expandable material.

20. The method of claim 16, further comprising securing the first layer, the second layer, and the intermediate layer together by a thread during sewing, keeping the first layer, the second layer, and the intermediate layer separated from each other except where they are secured together by the thread, and forming an air cavity between the first layer, the second layer, and the intermediate layer.

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