US-12626966-B2 - Battery cell thermal runaway barrier

US12626966B2US 12626966 B2US12626966 B2US 12626966B2US-12626966-B2

Abstract

A thermal runaway barrier for at least significantly slowing down a thermal runaway event within a battery assembly. The thermal runaway barrier consisting essentially of a single-layer of a nonwoven fibrous thermal insulation comprising a fiber matrix of inorganic fibers, thermally insulative inorganic particles dispersed within the fiber matrix, and a binder dispersed within the fiber matrix so as to hold together the fiber matrix. An optional organic encapsulation layer may also be used to encapsulate the nonwoven fibrous thermal insulation.

Inventors

Shailendra B. Rathod
Patrick Welter
Gary F. Howorth
Claus Middendorf
Kerstin C. Rosen
Tien Wu
Heonjoo Ha
Martin SCHASCHKE

Assignees

3M INNOVATIVE PROPERTIES COMPANY

Dates

Publication Date: 20260512
Application Date: 20210730

Claims (14)

1 . A thermal runaway barrier operatively adapted for being disposed between battery cells of a battery assembly and for at least significantly slowing down a thermal runaway event within the battery assembly, said thermal runaway barrier consisting essentially of: a single-layer of a nonwoven fibrous thermal insulation comprising a fiber matrix of inorganic fibers, thermally insulative inorganic particles dispersed within the fiber matrix, and a binder dispersed within the fiber matrix so as to hold together the fiber matrix; and an organic encapsulation layer encapsulating the single-layer of nonwoven fibrous thermal insulation.
2 . The thermal runaway barrier according to claim 1 , wherein the layer of nonwoven fibrous thermal insulation contains an amount of fiber shot in the range of from about 3% up to about 60% by weight of the amount of inorganic fibers in the layer of nonwoven fibrous thermal insulation.
3 . The thermal runaway barrier according to claim 1 , wherein the layer of nonwoven fibrous thermal insulation contains an amount of thermally insulative inorganic particles in the range of from as low as about 10% up to as high as about 60%, by weight of the layer of nonwoven fibrous thermal insulation.
4 . The thermal runaway barrier according to claim 1 , wherein the layer of nonwoven fibrous thermal insulation contains an amount of organic binder in the range of from as low as about 2.5% up to as high as about 10.0%, by weight of the layer of nonwoven fibrous thermal insulation.
5 . The thermal runaway barrier according to claim 1 , wherein the layer of nonwoven fibrous thermal insulation has an installed thickness in the range of from about 0.5 mm up to less than 5.0 mm.
6 . The thermal runaway barrier according to claim 1 wherein the layer of nonwoven fibrous thermal insulation has a basis weight in the range of from as low as about 250 g/m 2 and up to as high as about 1000 g/m 2 .
7 . The thermal runaway barrier according to a claim 1 wherein the layer of nonwoven fibrous thermal insulation has an uncompressed basis weight in the range of from about 250 g/m 2 up to about 400 g/m 2 .
8 . The thermal runaway barrier according to claim 1 , wherein the thermally insulative inorganic particles comprise particles of one or any combination of the materials selected from the group consisting of inorganic aerogel, xerogel, hollow or porous ceramic microspheres, unexpanded vermiculite, irreversibly or permanently expanded vermiculite, fumed silica, otherwise porous silica, irreversibly or permanently expanded or unexpanded perlite, pumicite, irreversibly or permanently expanded clay, diatomaceous earth, titania and zirconia.
9 . The thermal runaway barrier according to claim 1 , wherein the organic encapsulation layer has at least one vent hole formed therethrough that is located and sized to allow gas contained within the thermal runaway barrier to escape from the organic encapsulation, such that the structural integrity of the organic encapsulation layer is kept intact, during a thermal runaway event.
10 . The thermal runaway barrier according to claim 1 , wherein the thermal runaway barrier has a top edge, a bottom edge and opposite side edges, and the at least one vent hole is located along the periphery of one or both opposite side edges.
11 . The thermal runaway barrier according to claim 1 , wherein the at least one vent hole provides an exit opening through the organic encapsulation layer having an opening area in the range of from about 2 mm 2 up to about 15 mm 2 .
12 . The thermal runaway barrier according to claim 1 , wherein the layer of nonwoven fibrous thermal insulation has a peripheral edge, and the organic encapsulation layer is sealed around the peripheral edge.
13 . The thermal runaway barrier according to claim 1 , wherein the layer of nonwoven fibrous thermal insulation passes at least the V-2 level of the UL94 Flammability Test.
14 . A battery cell module for an electric vehicle, said battery cell module comprising: a plurality of battery cells disposed in a housing; and a plurality of thermal runaway barriers according to claim 1 , wherein the battery cells are lined up in a row, with one thermal runaway barrier being disposed between each pair of adjacent battery cells.

Description

CROSS REFERENCE TO RELATED APPLICATIONS This application is a national stage filing under 35 U.S.C. 371 of PCT/IB2021/056993, filed Jul. 30, 2021, which claims the benefit of Provisional Application No. 63/058,863, filed Jul. 30, 2020, the disclosure of which is incorporated by reference in its/their entirety herein. The present invention relates to a barrier for at least significantly slowing down a thermal runaway event within a battery assembly, e.g., like a battery assembly used in an electric vehicle. BACKGROUND Electric motors used in electric or hybrid vehicles (e.g., automobiles) are powered, at least in part, by batteries. Lithium ion batteries are typically used in such applications, and they are available in three forms: prismatic cells, pouch cells or cylindrical-shaped cells. These batteries are disposed within the vehicle compactly to save space. Sometimes one or more of the battery cells or battery modules experience a thermal runaway event, which can result in many if not all of the battery cells or battery modules overheating and being destroyed. There is a desire in the industry to prevent, stop or at least significantly slowing down such a thermal runaway event. The industry has developed a number of thermal barrier elements, which require multiple layers of various inorganic materials to perform such a function (see, e.g., U.S. Pat. No. 8,541,126B2). The background description provided here is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure. SUMMARY OF THE INVENTION The present inventors have discovered that suitable thermal barrier elements can be used without the need for multiple layers of inorganic nonmetallic materials. In one aspect of the present invention, a thermal runaway barrier is provided that is operatively adapted for being disposed between battery cells of a battery assembly and for at least significantly slowing down a thermal runaway event within the battery assembly. The thermal runaway barrier consists of or consists essentially of a single-layer of a nonwoven fibrous thermal insulation comprising a fiber matrix of inorganic fibers, thermally insulative inorganic particles dispersed within the fiber matrix, and a binder dispersed within the fiber matrix so as to hold together the fiber matrix. An optional organic encapsulation layer may also be included for encapsulating the single-layer of nonwoven fibrous thermal insulation. In another aspect of the present invention, a battery cell module or assembly for an electric vehicle is provided. The battery cell module or assembly comprises a plurality of battery cells disposed in a housing, and a plurality of thermal runaway barriers according to the present invention. The battery cells are lined up in a row or stack, with one thermal runaway barrier being disposed between each pair of adjacent battery cells, or between a predetermined number of battery cells (e.g., after every third battery cell), or between battery modules. In a further aspect of the present invention, a method is provided for making a thermal runaway barrier according to the present invention, where the method comprises forming the layer of nonwoven fibrous thermal insulation using a wet-laid process or dry-laid process. The above summary of the present invention is not intended to describe each disclosed embodiment or every implementation of the present invention. The description that follows more particularly exemplifies illustrative embodiments. In several places throughout the application, guidance is provided through lists of examples, which examples can be used in various combinations. In each instance, the recited list serves only as a representative group and should not be interpreted as an exclusive list. BRIEF DESCRIPTION OF THE DRAWINGS Descriptions corresponding to the included figures can be within this description. FIG. 1 is a schematic end view of a fiber matrix layer and an optional encapsulation layer that may be used in a thermal runaway barrier application. FIG. 2 is a schematic side view of a battery module of battery cells, with thermal runaway barriers disposed between adjacent battery cells. FIG. 3 is a schematic top view of a battery pack of battery modules, with thermal runaway barriers placed between adjacent battery modules and/or on the top of the battery modules. FIG. 4 is a photographic perspective view of a thermal runaway barrier encapsulated with an adhesive-backed organic polymeric layer with release liners and an expanding gas outlet/notch. FIG. 5 is a schematic side view of a Dry-laid process for manufacturing a battery cell thermal runaway barrier, according to one embodiment of the present invention. FIG. 6