Battery cell thermal runaway barrier

Abstract

A thermal runaway barrier for at least significantly slowing a thermal runaway event in a battery cell assembly. The thermal runaway barrier includes a layer of nonwoven fibrous insulation including a fibrous matrix of inorganic fibers, insulating inorganic particles of fumed silica dispersed within the fibrous matrix, and a binder dispersed within the fibrous matrix to hold the fibrous matrix together. An optional organic encapsulation layer may also be used to encapsulate the nonwoven fibrous insulation.

Description

[Technical Field]

[0001] The present invention relates to a barrier for at least significantly slowing down thermal runaway events in a battery assembly, such as a battery assembly used in an electric vehicle. [Background technology]

[0002] Electric motors used in electric or hybrid vehicles (e.g., automobiles) are at least partially powered by batteries. Lithium-ion batteries are typically used in such applications and are available in three forms: prismatic cells, pouch cells, or cylindrical cells. These batteries are compactly arranged within the vehicle to save space. In some cases, a thermal runaway event may occur in one or more battery cells or battery modules, causing many, if not all, of the battery cells or modules to overheat and be destroyed. The industry desires to prevent, stop, or at least significantly reduce such thermal runaway events. This invention contributes to addressing that issue.

[0003] The background art provided herein is intended to provide an overall context for the present disclosure. To the extent described herein, the inventors' research described herein, as well as any description that, without such description, would not qualify as prior art at the time of filing, are not considered prior art to this disclosure, either expressly or implicitly. [Overview of the Initiative]

[0004] In one aspect of the present invention, a thermal runaway barrier is provided comprising a layer of nonwoven fiber insulation comprising an inorganic fiber matrix, insulating inorganic particles containing fumed silica dispersed within the fiber matrix, and a binder dispersed within the fiber matrix to hold the fiber matrix together. An optional organic encapsulation layer may also be included to surround the layer of nonwoven fiber insulation. An optional inorganic encapsulation layer may also be included to surround the layer of nonwoven fiber insulation.

[0005] 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 arranged in a housing and a plurality of thermal runaway barriers according to the present invention. The battery cells are arranged in a row or in a stack, with one thermal runaway barrier positioned between each pair of adjacent battery cells, or between a predetermined number of battery cells (e.g., after every three battery cells), or between battery modules.

[0006] In a further aspect of the present invention, a method for producing a thermal runaway barrier according to the present invention is provided, the method comprising forming a layer of nonwoven fiber insulation using a wet process or a dry process.

[0007] The above summary of the present invention is not intended to describe each embodiment or all implementations disclosed herein. The following description provides more specific examples of exemplary embodiments. While several points throughout this application provide guidance by listing examples, these examples can be used in various combinations. In each case, the listed enumerated items serve only as representative groups and should not be interpreted as an exclusive enumeration. [Brief explanation of the drawing]

[0008] Descriptions corresponding to the included drawings may be within the scope of this specification.

[0009] [Figure 1] This is a schematic end view of a fiber matrix layer and an optional encapsulation layer that may be used in thermal runaway barrier applications. [Figure 2] This is a schematic side view of a battery module with battery cells having a thermal runaway barrier positioned between adjacent battery cells. [Figure 3] This is a schematic top view of a battery pack of battery modules, which has thermal runaway barriers placed between adjacent battery modules and / or on top of the battery modules. [Figure 4]A perspective photograph of a thermal runaway barrier encapsulated with a release liner and an adhesive organic polymer layer having an inflation gas outlet / notch. [Figure 5] A schematic side view of a dry process for manufacturing a battery cell thermal runaway barrier according to an embodiment of the present invention. [Figure 6] A cross-sectional view of an embodiment of a thermal runaway barrier showing a plurality of inflation gas vent holes formed through an encapsulation film according to an embodiment of the present invention. [Figure 7] A cross-sectional view of another embodiment of a thermal runaway barrier showing a plurality of inflation gas vent holes in the form of notches formed through an encapsulation film according to another embodiment of the present invention. [Figure 8] A top view of an additional embodiment of a thermal runaway barrier having two different types of inflation gas vent holes formed through an encapsulation film (encapsulation film).

Mode for Carrying Out the Invention

[0010] When describing the preferred embodiments of the present invention, specific terms are used for clarity. However, the present invention is not intended to be limited to the specific terms so selected, and each such selected term includes all technical equivalents that act in a similar manner.

[0011] As used herein, the terms "preferred" and "preferably" refer to the embodiments described herein that can provide certain advantages under certain circumstances. However, other embodiments may also be preferred under the same or other circumstances. Furthermore, the listing of one or more preferred embodiments does not imply that other embodiments are not useful, nor is it intended to exclude other embodiments from the scope of the present invention.

[0012] As used herein and in the appended claims, unless otherwise specified in the context, the singular forms "a," "an," and "the" refer to multiple references. Thus, for example, a reference to a component preceded by "a" or "the" may include one or more of the component and its equivalents known to those skilled in the art. Furthermore, the term "and / or" means one or all of the enumerated elements, or any combination of two or more of the enumerated elements.

[0013] Note that the term "including" and its variations are not restrictive when they appear in the attached description. Furthermore, "a," "an," "the," "at least one," and "one or more" are used interchangeably herein. Relative terms such as left, right, front, rear, top, bottom, side, above, below, horizontal, and vertical may be used herein, in which case they refer to the viewpoints shown in the drawings. However, these terms are used only to simplify the description and do not in any way limit the scope of the invention.

[0014] Throughout this specification, any reference to “one embodiment,” “a specific embodiment,” “one or more embodiments,” or “embodiment” means that a particular functional part, structure, material, or feature described in relation to that embodiment is included in at least one embodiment of the present invention. Therefore, the appearance of phrases such as “in one or more embodiments,” “in a specific embodiment,” “in one embodiment,” or “in an embodiment” in various places throughout this specification does not necessarily refer to the same embodiment of the present invention. Trademarks, where applicable, are written in all capital letters.

[0015] The term "and / or" means one or all of the listed elements, or any combination of two or more of the listed elements (for example, preventing pain and / or treating pain means preventing further pain, treating pain, or both treating and preventing pain).

[0016] In this specification, the term "or" generally includes "and / or" unless otherwise explicitly stated in the content.

[0017] Furthermore, in this specification, an enumeration of numerical ranges by endpoints includes all numbers contained within that range (for example, 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, 5, etc.).

[0018] "Ambient conditions" means a temperature of 25°C and a pressure of 101.3 kPa.

[0019] Unless otherwise specified, "average" refers to the numerical mean.

[0020] "Continuous" means extending across a single, unified region along a given layer (a perforated sheet can be continuous).

[0021] "To harden" refers to exposure to any form of radiation, heating, or causing a physical or chemical reaction that results in solidification or an increase in viscosity.

[0022] "Discontinuity" means extending across multiple distinct regions along a given layer, where these distinct regions are separated from one another.

[0023] "Size" refers to the longest dimension of a given object or surface.

[0024] "Substantially" means a significant amount, such as 50%, 60%, 70%, 80%, 90%, 95%, 96%, 97%, 98%, 99%, 99.5%, 99.9%, 99.99%, or 99.999%, or 100%.

[0025] "Thickness" refers to the distance between opposing surfaces of a single-layer or multi-layer article.

[0026] The enumeration of numerical ranges by endpoints is, unless otherwise specified, based on the precision indicated by the endpoints of the specified range and any range within that range (for example, for the range 1.000 to 5.000, the increment is 0.001, and the ranges are 1.000, 1.001, 1.002, 1.100, 1.101, 1.102, 2.000, 2.001, 2. This includes all numbers within that range, such as 002, 2.100, 2.101, 2.102, 3.000, 3.001, 3.002, 3.100, 3.101, 3.102, 4.000, 4.001, 4.002, 4.100, 4.101, 4.102, 5.000, 5.001, 5.002, etc. (up to a maximum of 5.999).

[0027] The term "polymer" is understood to include polymers, copolymers (for example, polymers formed using two or more different monomers), oligomers and combinations thereof, as well as polymers, oligomers, or copolymers that may be formed in miscible blends.

[0028] The following examples have been selected solely to further illustrate the features, advantages, and other details of the present invention. However, while the examples serve this purpose, it should be explicitly understood that the specific raw materials and quantities used, as well as other conditions and details, should not be interpreted in a way that unnecessarily limits the scope of the invention.

[0029] Referring to Figure 1, the fiber matrix layer 10 useful for thermal runaway barrier applications contains nonwoven inorganic (i.e., nonmetallic) or other heat-resistant fiber insulating material, thermal insulating ceramic or other nonmetallic inorganic particles, and an organic or inorganic binder. As used herein, nonmetallic means not metal or metal alloy. Optionally, the fiber matrix layer 10 is encapsulated with an organic polymer layer 12.

[0030] Referring to Figure 2, an exemplary battery module 20 includes an assembly of battery cells 22 and a plurality of thermal runaway barriers 24. Each thermal runaway barrier 24 may be in the form of one or more fibrous matrix layers 10, with or without an encapsulation body 12, and may be fabricated from the exemplary materials described herein. The thermal runaway barriers 24 may be located at one or more positions throughout the battery module 20, between adjacent battery cells 22, between groups of cells 22, or both. Typically, the battery module 20 is placed on a cooling plate 26 and a tray 28.

[0031] Referring to Figure 3, the exemplary battery pack 30 includes a plurality of battery modules 20, each of which may have its own cooling plate 26 and tray 28, or all of the modules 20 may share the same cooling plate 26 and tray 28. A thermal runaway barrier 24 formed from the exemplary materials described herein may be positioned between one or more adjacent battery modules 20, on one or more or all of the battery modules 20 (see reference no. 24'), or in any combination of both. One or more thermal runaway barriers 24 may also be sized to cover the top of all of the battery modules 20.

[0032] Referring to Figure 4, an exemplary thermal runaway barrier 24 includes one or more fiber matrix layers (not shown) encapsulated by an organic polymer layer 12 covering both sides and periphery of one or more fiber matrix layers. In one embodiment, opposing main surfaces of the encapsulation layer 12 are coated with an adhesive (e.g., a pressure-sensitive adhesive) protected by corresponding release liners 14 and 16. Preferably, the encapsulation layer 12 includes one or more outlets or openings 18 (e.g., in the form of notches) that allow air (e.g., hot air) or other gases to escape from the inside of the encapsulation 12, rather than causing the encapsulation 12 to swell and expand like a balloon when, for example, the air trapped inside the encapsulation 12 is heated to a high temperature (e.g., when the temperature of one or more of the adjacent battery cells 20 rises).

[0033] Referring to Figure 5, the thermal runaway barrier 20 according to the present invention can be manufactured using conventional dry manufacturing equipment and processes. Examples of such equipment and processes can be found in U.S. Patent No. 9,580,848 (Henderson et al.), No. 9,475,034 (Vincent et al.), No. 7,491,354 (Anderson), and No. 6,808,664 (Falk et al.). Such equipment may include a chamber or forming box 40 with multiple feeder inlets, including an inlet 42 for supplying any desired combination of fibers, binder, and particles into the box 40, and a plurality of inlets 44, 44', and 44'' for supplying any desired number or type of filler material into the box 40. After mixing the fibers with the other raw materials, the resulting nonwoven fiber material 45 is placed on a belt 46, which carries the material 45 through a baking oven 47, where the binder is cured so that the fiber material 45 can be further processed. The nonwoven fiber material 45' is then processed into individual nonwoven fiber layers 10 (not shown) by die-cutting, laser cutting, waterjet cutting, or other methods, and then processed at the encapsulation station 48 by laminating a polymer film 12 (not shown) to both sides of a single layer 10 or a stack of two or more layers 10, for example. An optional hot-melt adhesive or pressure-sensitive adhesive can be applied to one or both sides of the encapsulation body 12 at the corresponding spray stations 49 and 49'. Subsequently, a protective release liner (not shown) can be applied to each bonded surface.

[0034] Referring to Figure 6, one embodiment of the thermal runaway barrier 24 according to the present invention includes one or more vents 52 formed through one or both layers of the encapsulating film 12. The vents 52 can have any desired shape (e.g., circular, rectangular, elliptical, etc.), and preferably the vents 52 are formed through portions of the film 12 that are located beyond the periphery of the encapsulated fiber layer 10 but still within the periphery of the encapsulation body 12, and also provide a path for expanding gas (e.g., air) to escape from the space containing the fiber layer 10. The number, size, and location of these vents 52 can be varied as needed.

[0035] Referring to Figure 7, another embodiment of the thermal runaway barrier 24 according to the present invention includes two vents 54, each in the form of a notch formed through the encapsulation film 12. The vents 54 can have any desired shape (e.g., semicircular, rectangular, semielliptical, etc.), and preferably the notches 54 are formed through a portion of the film 12 that is located beyond the periphery of the encapsulated fiber layer 10 and past the periphery of the encapsulation body 12, and also provide a path for expanding gas (e.g., air) to escape from the space containing the fiber layer 10. The number, size, and position of these notches 54 can be varied as needed.

[0036] Referring to Figure 8, an additional embodiment of the thermal runaway barrier 24 according to the present invention includes two different types of vents 52 and 54 formed through the encapsulation body 12, similar to those described above with respect to Figures 6 and 7.

[0037] [Table 1]

[0038] Test method High temperature side / low temperature side test 1 (HCST1) Using an MTS Insight 5kN tensile testing machine (obtained from MTS Insight (Eden Prairie, MN, United States)), the lower platen was heated to 600°C, and the sample was placed on top. The upper platen, which had a thermocouple embedded in it, was lowered so that the distance between the two platens was 1.6 mm. The temperature rise on the lower side was recorded (continuously) against time until it reached 900 seconds (15 minutes).

[0039] High temperature side / low temperature side test 2 (HCST2) Using a 10kN tensile testing machine (obtained from ZWICKROELL (Ulm, Germany)), the upper platen was heated to 600°C, and the sample was placed on the lower platen, which contained a thermocouple set to ambient temperature. A heat shield was used to cover the sample and maintain it at ambient temperature. The heat shield was then removed, and the upper platen was lowered while maintaining a pressure of 1 MPa. The time required for the sample to reach a temperature of 150°C (302°F) (specified as t(150°C)) was recorded.

[0040] shear strength The ASTM273C 273M method was followed. A shear rate of 5 minutes was used.

[0041] Thermal conductivity test Thermal conductivity measurements were obtained using a Thermal Constants Analyzer, model TPS 2500S, obtained from Hot Disk® AB (Goteborg, Sweden). Measurements were performed by selecting the isotropic / bulk (Type I) module in the software. A 3.2 mm diameter Kapton 5465 sensor (Hot Disk®) was used. As specified in the manual, the lateral dimensions of the sample must be 1.5 to 2.0 times the sensor radius. The sample thickness must also be equal to or greater than the sensor radius. To ensure the thickness was sufficiently greater than the sensor radius, 3-4 layers of sample were stacked on either side of the sensor, and small pressure was applied to ensure all layers were in contact with each other.

[0042] The specified parameters were 1) measurement time in seconds, and 2) heating power in mW. The sample temperature was entered as ambient room temperature. Then, the measurement was performed as specified in the TPS manual.

[0043] The results were analyzed by clicking "Calculate" in the software and selecting the "Standard Analysis" option. After the measurement, several graphs were displayed by the software, including a "Transient" graph and a "Residual" graph. The transient graph displays the temperature rise of the sensor during heating of the sample up to 200 points. The first pass analyzing the results started from point 10 and included all transient points up to 200. If the residual graph did not appear to have a random distribution of points, a smaller subset of data points was used for the analysis. This was done by trimming points from the beginning and end of the measurement. As a rule, if the number of points used in the analysis was less than 50, the results were unreliable. In addition to meeting the quality requirements for the residual plot, several other numerical requirements were set, including "Probe Depth (PD)", "Temperature Rise (TI)", "Total Time to Characterization (TCT)", and "Mean Deviation (MD)" as specified in the manual. For these specifications, PD must be less than the thickness of the sample, TI must be between 0.4K and 4.0K, TCT must be between 0.33 and 1.0, and MD must be 10⁻⁴ or better. If these five criteria were not met, the heating power and measurement time were adjusted. The settings were repeated until an accurate measurement was obtained, and accuracy was defined by meeting all the numerical requirements described in the manual. For the test samples, the thermal conductivity value in W / m·K was measured and recorded.

[0044] Examples 1-8 (EX1-EX8) and Comparative Examples 1-2 (CE1-CE2) For Examples 1, 3, and 5-7, the staple fiber combinations were weighed in weight percent (as specified in Table 2) and pre-mixed by hand before being placed on the feed belt. The fiber material was processed by an airlaid machine such as disclosed in U.S. Patent No. 7,491,354 (i.e., fed from above), where the fibers were opened, dispersed in an airflow, and then collected on a screen belt. Details of such airlaid machines and methods of using such machines in forming airlaid webs can be found in U.S. Patents No. 9,580,848 (Henderson et al.), No. 9,475,034 (Vincent et al.), No. 7,491,354 (Anderson), and No. 6,808,664 (Falk et al.). The filler was supplied in weight percent (as specified in Table 2) from the top or side into the chamber or forming box of the airlaid machine. The packing material was uniformly distributed onto the web using a positive displacement feeder coupled with an air-driven horn. The sample was then fed at a speed of 1.1 m / min into a forced-air convection oven at 143.3°C (290°F).

[0045] Examples 2 and 4 followed the process described in Example 1 of U.S. Patent No. 5,869,010 (Langer). Samples were assembled containing the weight percentages of fibers and fillers specified in Table 2, rather than the materials specified in U.S. Patent No. 5,869,010.

[0046] Example 8 followed Example A of U.S. Patent No. 9,399,864 (Samanta et al.), with the modifications described. An aerogel slurry was prepared by adding 400 grams of Barlox 12 (obtained from Lonza Group (Basel, Switzerland)) to 379 liters (100 gallons) of water at 43°C (110°F). The slurry was mixed. 200 grams of Foamaster 111 (obtained from BASF Group (Ludwigshafen, Germany)) was added and the slurry was mixed. EAF68 was added by weight percentage (as specified in Table 2) and mixed. Then AG was added by weight percentage (as specified in Table 2) and mixed. The slurry was mixed for 15 minutes, and 200 grams of MOJO MP 9307C was added and mixed. A fiber slurry was prepared by adding 717 grams of Microstrand 110X-481 (obtained from John Manville, Denver, CO, United States) to 2271 liters (600 gallons) of water. The slurry was pulped for 60 seconds at 500 rpm. T255 was added by weight percentage (as specified in Table 2), and the slurry was pulped for 30 seconds at 500 rpm. A further 1136 liters (300 gallons) of water was added to the slurry. 757 liters (200 gallons) of the fiber slurry was mixed with 379 liters (100 gallons) of aerogel slurry, and SW+ was added by weight percentage (as specified in Table 2). The combined slurry was processed in a papermaking machine.

[0047] [Table 2]

[0048] These samples were subjected to the HCST1 test, and the results are shown in Table 3.

[0049] [Table 3]

[0050] Examples 9-34 (EX9-EX34) and Comparative Examples 3-8 (CE3-CE8) The materials were substituted as shown in Table 4, according to the "General Procedure for Preparing Fibrous Sheet" described in U.S. Patent Application Publication No. 2010 / 0115900. Three liters of tap water (18°C) and inorganic fibers washed to a shot content of less than 50% by weight of 60 grams (g) were added to a GT800 Classic Blender (obtained from Rotor Lips Ltd (Uetendorf, Switzerland)). The blender was operated at low speed for 5 seconds. The resulting slurry was rinsed with one liter of tap water (18°C) in an RW16 mixing vessel equipped with a paddle mixer (obtained from IKA-Werke GmbH (Staufen, Germany)). The slurry was further diluted with one liter of tap water (18°C). The diluted slurry was mixed at a moderate speed to maintain a suspended solid state. An antifoaming agent (obtained from Henkel (Edison, NJ) under the trade name "FOAMASTER 111" (0.3g)) and ethylene-vinyl acetate terpolymer latex (obtained from Air Products under the trade name "AIRFLEX 600BP" (6.0g, 55% solids by weight)) were added. A flocculant was added dropwise in the amounts shown in Table 4. Then, insulating particles were added as shown in Table 4. The mixer speed was increased and mixing was continued for 1 to 5 minutes. The paddle mixer was removed, and the slurry was poured into a 20cm x 20cm (8-inch x 8-inch) sheet forming machine (obtained from Williams Apparatus Co (Watertown, NY, United States)) and drained. The surface of the drained sheet was rolled with a rolling pin to remove excess moisture. The sheet was then pressed between absorbent paper at a surface pressure of 90-97 kPa (13-14 psi) for 5 minutes. Next, the sheets were dried in a forced-air oven at 150°C for 10-15 minutes and then allowed to equilibrate overnight while exposed to ambient air. The thickness and basis weight of the samples were measured at a constant pressure of 4.9 kPa and recorded in Table 5. In Examples 15-25 (EX15-EX25), the vermiculite material used in these samples was either preheated to permanently pre-expand the vermiculite before being used in sample preparation, or post-heated after sample preparation to permanently post-expand the vermiculite under specific time and temperature conditions.In EX21, the vermiculite was preheated at 300°C for 6 hours before the sample was assembled. In EX22 and EX23, the vermiculite was heated at 450°C for 30 minutes after the sample was assembled. In EX24, the vermiculite was preheated at 500°C for 30 minutes before the sample was assembled. In EX25, EX33, and EX34, the vermiculite in the sample was preheated at 1000°C for 30 minutes before the sample was assembled.

[0051] [Table 4]

[0052] These samples were subjected to the HCST2 test, and the results are shown in Table 5.

[0053] [Table 5]

[0054] Example 35 (EX35) PP was laminated onto the sample assembled in Example 5. Both sides of the hand-held sample were hot-pressed at 132°C (270°F) and 200kPa. The edges were manually sealed using an impulse sealer at 149°C (300°F), heated for 2 seconds, and cooled for 10 seconds. All steps were performed under a compressive force of 524kPa (76psi). The thickness of the PP film was 0.02mm (1 mil). A shear strength test was performed on a 600gsm sample, and the results are shown in Table 6.

[0055] Example 36 (EX36) Hot melt adhesive H2345 was applied to the sample of Example 35 using a Nordson Altablue grid melter equipped with a 15.24 cm (6 inch) meltblown adhesive die. The adhesive was heated to 193°C (380°F) and sprayed onto the web at an air pressure of 206.8 kPa (30 psi) and a pump speed of 20 RPM. Shear strength tests were performed on a 600 gsm sample, and the results are shown in Table 6.

[0056] Example 37 (EX37) Using an ACCUSPRAY ONE spray gun system containing PPS obtained from 3M Company (St. Paul, MN, United States), FB was spray-coated onto the sample assembled in Example 35. One side of the hand sample was spray-coated, then it was flipped over and the other side was coated. Shear strength tests were performed on the 600 gsm samples, and the results are shown in Table 6.

[0057] Example 38 (EX38) An adhesive was prepared by dissolving PKHH phenoxy resin, obtained from Gabriel Performance Products (Akron, OH, United States), in a 50% solution of methyl ethyl ketone (MEK). The MEK was further evaporated at room temperature for 60 minutes. Two coatings of the adhesive were applied to one side of a 0.076 mm (3 mil) PET film obtained from Dupont (Wilmington, DE, United States). Two coatings of the adhesive were applied to one side of another 0.076 mm (3 mil) PET film. The thickness of the adhesive coating was 0.036 mm (1.4 mil). The PET sample films coated with the adhesive were placed on the top and bottom surfaces of the sample assembled in Example 5. A shear strength test was performed on the 600 gsm sample, and the results are shown in Table 6.

[0058] [Table 6]

[0059] Examples 39-40 (EX39-EX40) Using the materials specified in Table 7, samples were assembled using the procedures described in Examples 9-16. The thickness and basis weight of the samples were measured at a constant pressure of 4.9 kPa and recorded in Table 8. These samples were subjected to the HCST2 test, and the results are shown in Table 8.

[0060] [Table 7]

[0061] [Table 8]

[0062] Examples 41-57 (EX41-EX57) Staple fiber combinations by basis weight (as specified in Table 9) were weighed and processed through an airlaid machine. Details of the apparatus and the method of using the apparatus to form airlaid webs are described in U.S. Patents 9,580,848 (Henderson et al.), 9,475,034 (Vincent et al.), 7,491,354 (Anderson), and 6,808,664 (Falk et al.). The combined staple fibers were then processed again through the airlaid machine, and the fumed silica filler was supplied directly to the airlaid machine chamber by basis weight (as specified in Table 2). The filler was uniformly distributed to the web using a screw feeder. The web was then fed into a forced-air convection oven at 148.89°C (300°F) at speeds of 0.25 m / min and 1.5 m / min. The thickness of the samples ranged from 0.5 to 15 mm.

[0063] Next, the web was densified to a specific gap thickness using a hot press. Polytetrafluoroethylene (PTFE) coated glass fiber fabric sheets (obtained from McMaster-Carr (Elmhurst, IL, United States)) were placed on both sides of the sample, and the sample was placed between two hot plates maintained at a temperature of 148.89°C (300°F). Pressure was applied for 30–120 seconds to activate the two-component fibers (T255). The densified sample was then immediately placed under pressure between two plates maintained at room temperature for 30–120 seconds to set the web to the desired thickness.

[0064] [Table 9]

[0065] These samples were subjected to the HCST2 test, and the results are shown in Table 10. The actual thickness of the samples was measured according to ASTM D5736-95 after removing the glass fiber fabric sheet. The plate pressure was calibrated to 0.002 psi (13.790 Pascals).

[0066] [Table 10]

[0067] The density of 1000 gsm samples (shown in EX48-EX53) containing 40% fumed silica was calculated by dividing the actual basis weight (gsm) by the actual thickness (mm). Table 11 shows the density and low-temperature values ​​recorded after a 3600-second HCST2 test for EX48-EX53. This table is sorted in descending order of the measured low-temperature values.

[0068] [Table 11]

[0069] A thermal conductivity test was conducted, and the results are shown in Table 12.

[0070] [Table 12]

[0071] Surprisingly, fumed silica was found to have a higher thermal conductivity than silica aerogel. The thermal conductivity of nonwoven fiber insulation materials (i.e., fiber matrices) that do not contain fumed silica particles is thought to be lower than that of the same fiber matrix containing fumed silica particles.

[0072] Additional Embodiments Embodiment of a battery cell thermal runaway barrier 1. A thermal runaway barrier, for example, positioned between adjacent battery cells (e.g., prismatic or pouch-type battery cells) of a battery module or assembly (i.e., a series of battery cells stacked in a row) used to supply power to an electric motor (e.g., used in electric vehicles or hybrid vehicles), which is adapted (i.e., designed, constructed, formed, and / or dimensionally determined) or otherwise suitable to act in a manner that prevents, stops, or at least significantly slows down thermal runaway events within the battery module or assembly or between adjacent battery modules or assemblies, One or more layers of dry or wet nonwoven fiber insulation (e.g., in the form of mats, sheets, strips, or three-dimensional thin-walled structures) comprising a fiber matrix of ceramic or other non-metallic (i.e., not metal, metal alloy, or metal composite) inorganic fibers, Thermal insulating inorganic particles containing fumed silica dispersed uniformly, evenly, throughout, or otherwise throughout, or to the extent permitted by the manufacturing process (e.g., in both dry and wet processes, some particles may settle at the bottom of the mat), and organic or inorganic binders dispersed uniformly, evenly, throughout, or otherwise throughout, or to the extent permitted by the manufacturing process, to bind the inorganic filler particles and inorganic fibers together, or to hold the fiber matrix together to at least as much as necessary to withstand the degree of handling otherwise required before placement between battery cells (e.g., during the encapsulation process), An optional organic (e.g., polymer, paper, etc.) encapsulation layer (e.g., one or more opposing sandwich layers, each layer being in the form of a film, coating, organic fiber nonwoven fabric, or woven fabric, etc.) that surrounds, or otherwise encapsulates, all, most, or part of the main surfaces of at least one or both of the nonwoven fiber insulation layers, and preferably all, most, or part of the peripheral edges of the nonwoven fiber insulation layers, to prevent or significantly reduce the shedding or loss of inorganic fibers or particles from the encapsulated layer of the nonwoven fiber insulation, An optional inorganic material (e.g., 25-80 g / m²) is used to surround, or otherwise enclose, all, most, or part of the main surfaces of at least one or both of the layers of the nonwoven fiber insulation, and preferably all, most, or part of the periphery of the nonwoven fiber insulation layer, to prevent or significantly reduce the shedding or loss of inorganic fibers or particles from the enclosed layer of the nonwoven fiber insulation. 2 A thermal runaway barrier comprising a glass fiber woven fabric encapsulation layer (for example, one or more opposing sandwich layers, each layer being in the form of an inorganic coating, or a nonwoven or woven fiber fabric).

[0073] A reduction in inorganic fiber or particle shedding is significant if the number of lost inorganic fibers or particles is less than 10% by weight, less than 5% by weight, or less than 1% by weight of the original fiber or particle content of the nonwoven fiber insulation layer. The thinner the organic encapsulation layer (i.e., the lower the organic content of the barrier), the better the results of high / low temperature tests.

[0074] The thermal runaway barrier of the present invention may also be used between battery modules or assemblies.

[0075] Inorganic binders, organic binders, or combinations thereof may be useful according to the present invention, and may include, for example, those disclosed in U.S. Patent No. 8,834,759. Examples of inorganic binders useful in both dry and wet fiber processing include silicone particles that convert to fusible silica when heated. Organic-inorganic hybrid binders such as WACKER® MQ 803 TF, which is a co-hydrolysis product of tetraalkoxysilane (Q units) and trimethylalkoxysilane (M units), may also be useful. The chemical structure of WACKER® MQ 803 TF can be viewed as a three-dimensional network of polysilicic acid units end-sealed with trimethylsilyl groups. Several residual ethoxy and hydroxyl functional groups are present. The average molecular weight can be precisely controlled by the ratio of M units to Q units. This ratio is approximately 0.67 for WACKER® MQ 803 TF.

[0076] An exemplary binder fiber is the use of two-component core-sheath polymer fibers in a dry process. In a wet process, ethylene vinyl acetate latex dispersion binders, two-component core-sheath polymer fibers, or a combination of both can be used. When polymer binder fibers are used, the binder can be activated by heating and compressing the nonwoven fiber insulation material. A combination of organic and inorganic binders can also be used.

[0077] As used herein, the term “inorganic” refers to ceramic or other non-metallic (i.e., not metals, metal alloys, or metal composites) inorganic materials.

[0078] "Thermal runaway" refers to a phenomenon where a battery cell undergoes a heat chain reaction, causing its temperature to rise uncontrollably. This heat chain reaction can be triggered by reasons such as overheating, overvoltage, and mechanical puncture of the battery cell.

[0079] "Heat propagation" refers to a situation where thermal runaway in one battery cell causes thermal runaway in the remaining battery cells within the battery pack or system.

[0080] A "thermal runaway event" refers to the overheating of one battery cell within a battery cell casing, which can trigger a chain reaction of overheating in adjacent battery cells until the number of overheated battery cells reaches a critical point of propagation, destroying all or more of the battery cells in the module or assembly of modules, potentially leading to explosion or fire. Factors that can cause battery cell overheating include physical damage, overvoltage application, and overheating (internal short circuit of the battery cell).

[0081] As the energy density of a battery cell increases, the temperature at which the battery cell begins to malfunction (e.g., from at least losing its efficiency or ceasing to function, to igniting, burning, or exploding) decreases. Similarly, as the energy density of a battery cell decreases, the temperature at which the battery cell begins to malfunction increases. For example, with a controlled temperature rise, NMC811 type battery cells tend to begin malfunctioning or even rupture when the temperature reaches approximately 120°C to 130°C, while NMC622 type battery cells tend to begin malfunctioning or even rupture when the temperature reaches approximately 180°C. The corresponding temperatures are higher for battery cells with lower energy density (e.g., NMC532 and NMC433 type battery cells). When using physically larger battery cells or when the temperature rises rapidly, heat diffusion through the battery cell may cause it to take longer for the local temperature to reach a critical point. This heat diffusion effect may increase the actual temperature at which the battery cell begins to malfunction or explode to some extent. In some cases, it is desirable that the thermal runaway barrier of the present invention prevent adjacent batteries from reaching temperatures in the range of approximately 130°C to approximately 150°C.

[0082] As used herein, "preventing" a thermal runaway event means preventing overheating of a single battery cell from causing overheating of adjacent battery cells. The barrier is considered to prevent a thermal runaway event if the adjacent battery cells do not exceed 130°C, 135°C, 140°C, 145°C, or 150°C.

[0083] As used herein, “stopping” a thermal runaway event means that the overheating of a battery cell causes only adjacent battery cells (i.e., three, two, or one battery cell away from either side of the overheating battery cell) to overheat, and the remaining battery cells in the battery module or assembly do not overheat.

[0084] As used herein, “decelerating” a thermal runaway event means that the event is delayed for at least a sufficiently long time so that personnel adjacent to the battery module or assembly (e.g., occupants in the passenger compartment of an electric vehicle) can escape to a safe distance from the battery module or assembly before being injured by the thermal runaway event. If a battery cell malfunctions (e.g., ignites or overheats to the point of non-functioning) and a thermal barrier is in place between the battery cells, the time it takes for the malfunction (e.g., ignites or overheats) to propagate to any adjacent battery cell is at least 5 minutes, preferably 10 minutes, or even more than 20 minutes.

[0085] 2. The fumed silica particles are approximately 100 m 2 / g~about 400m 2 A thermal runaway barrier according to Embodiment 1, having a surface area in the range of / g.

[0086] Examples of inorganic particles include particles of irreversibly or permanently expanded expandable materials and irreversibly or permanently expanded pearlite minerals. For example, inorganic particles containing voids, such as those found in irreversibly or permanently expanded vermiculite, are particularly desirable. While particles of irreversibly or permanently expanded pearlite minerals also contain voids, pearlite minerals are harder and less compressible than vermiculite minerals.

[0087] As used herein, irreversibly or permanently expanded expandable particles (e.g., particles of expandable materials such as vermiculite and perlite minerals) refer to particles that have been heated to a temperature and time such that they are irreversibly or permanently expanded to at least 10% to 100% of their expansion capacity, either by pre-expansion before being used to form a thermal runaway barrier, or by post-expansion after being incorporated into a nonwoven fiber insulation.

[0088] Expandable particles (e.g., vermiculite particles) can be permanently expanded by overheating them beyond the point of reversibility (e.g., in the range of approximately 350°C to 1000°C for vermiculite). Such permanently expanded expandable particles (e.g., vermiculite particles) may have an expanded accordion or worm-like structure that is more elongated, less dense, and less mechanically stable compared to the same particles in their non-expanded state, making them more prone to breaking down into smaller particles. As the heating temperature increases, the degree of permanent expansion of the particles increases (i.e., the particles can become larger and / or longer). In some cases, it may be desirable to use vermiculite that has been permanently expanded by chemical treatment (see, for example, "Chemical Exfoliation of Vermiculite and the Production of Colloidal Dispersions," GFWalker, WGGarrett, Science, April 21, 1967: Vol. 156, 3773rd edition, pp. 385-387, DOI: 10.1126 / science.156.3773.385; and https: / / science.sciencemag.org / content / 156 / 3773 / 385.abstract).

[0089] Since expanded particles decompose more easily, it may be desirable to post-expand the expandable particles after the non-expanded expandable particles have been incorporated into the nonwoven fiber insulation. Even using a gentle treatment that does not substantially decompose the particles, incorporating pre-expanded expandable particles into the nonwoven fiber insulation can still result in expanded particles that are oriented in the plane of the insulation (i.e., along the x-axis, y-axis, and / or between them). For example, with pre-expanded vermiculite particles, elongated particles may be roughly aligned with the fibers in the longitudinal or downstream direction (i.e., the y-axis) rather than in the thickness direction (i.e., the z-axis) of the nonwoven fiber insulation.

[0090] In contrast, when they are post-expanded (i.e., after the nonwoven fiber insulation is made from non-expanded expandable particles), the expanded expandable particles are not primarily oriented in the plane of the insulation. Non-expanded expandable particles typically have a more uniform structural shape (i.e., an aspect ratio closer to 1) compared to the same particles in the expanded state. This more uniform structural shape is thought to be less affected by fiber alignment during the formation of the nonwoven fiber insulation. As a result, post-expanded expandable particles are more likely to be isotropically oriented within the nonwoven fiber insulation. For example, in post-expanded vermiculite particles, elongated particles can be aligned in the thickness direction (i.e., the z-axis), in the plane (i.e., the x-axis, y-axis, and / or between them), or outside those axes. This difference in orientation between pre-expanded and post-expanded particles is thought to be caused by the non-expanded particles having a more uniform structural shape than those exhibited in the expanded state.

[0091] 3. The thermal runaway barrier according to Embodiment 1 or 2, wherein the nonwoven fiber insulation layer contains an amount of inorganic fibers ranging from a low value of about 15-19% by weight of the nonwoven fiber insulation layer to a high value of about 70, 75, 80, 85, or 90% by weight.

[0092] 4. A thermal runaway barrier according to any one of Embodiments 1 to 3, wherein the nonwoven fiber insulation layer contains fiber shots in an amount ranging from about 3% to about 60% by weight of the amount of inorganic fibers in the nonwoven fiber insulation layer.

[0093] In one embodiment, when no insulating particles are added, the inorganic fiber content is 95.2% by weight in the dry process and 95.5% by weight in the wet process. At the lowest level of insulating particle (e.g., aerogel particles) filling, the inorganic fiber content is 72% by weight for both the dry and wet processes. In the case of dry nonwoven fiber insulation, the fibers are opened (i.e., bulk fibers are separated and made low-density), which can remove some shots. In the case of wet nonwoven fiber insulation, the fibers are wet-washed, which removes more shots than are removed by the dry fiber opening process. Unwashed SuperWool Plus from Morgan has about 40% shots, and the actual fiber material content in nonwoven fiber insulation is 19-43%. Nonwoven fiber insulation may be desirable to have a fiber content in the range of about 10% to about 80%. Less fiber requires more organic binders. Other additives (e.g., flame retardants, heat absorbers, infrared reflectors, etc.) may be included.

[0094] 5. A thermal runaway barrier according to any one of Embodiments 1 to 4, wherein the nonwoven fiber insulation layer contains thermal insulating inorganic particles in an amount ranging from a low value of about 10%, 15%, 20%, 25%, 30%, or 35% by weight of the nonwoven fiber insulation layer to a high value of about 40%, 45%, 50%, 55%, or 60% by weight. For example, a high particle content of 60% can be achieved using a dry process, and a high particle content of 50% can be achieved using a wet process.

[0095] 6. A thermal runaway barrier according to any one of Embodiments 1 to 5, wherein the nonwoven fiber insulation layer contains an amount of organic binder ranging from a low value of about 2.5% by weight, 3.0% by weight, 3.5% by weight, 4.0% by weight, 4.5% by weight, 5.0% by weight, 5.5% by weight, 6.0% by weight, or 6.5% by weight to a high value of about 7.0% by weight, 7.5% by weight, 8.0% by weight, 8.5% by weight, 9.0% by weight, 9.5% by weight, or 10.0% by weight.

[0096] 7. A thermal runaway barrier according to any one of Embodiments 1 to 6, wherein the nonwoven fiber insulation layer has an installation (i.e., compressed) thickness in the range of about 0.5 mm to less than 5.0 mm. In particular, the installation (i.e., compressed) thickness is in the range of about 0.5 mm to about 2.5 mm, with a lower limit of about 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1.0 mm, 1.1 mm, 1.2 mm, 1.3 mm, 1.4 mm, or 1.5 mm, and an upper limit of about 1.6 mm, 1.7 mm, 1.8 mm, 1.9 mm, 2.0 mm, 2.1 mm, 2.2 mm, 2.3 mm, 2.4 mm, or 2.5 mm. In some applications, the installation thickness can be even higher, approximately 2.6mm, 2.7mm, 2.8mm, 2.9mm, 3.0mm, 3.1mm, 3.2mm, 3.3mm, 3.4mm, 3.5mm, 3.6mm, 3.7mm, 3.8mm, 3.9mm, 4.0mm, 4.1mm, 4.2mm, 4.3mm, 4.4mm, 4.5mm, 4.6mm, 4.7mm, 4.8mm, 4.9mm, or less than 5.0mm. The installation thickness of a nonwoven fiber insulation layer is almost always less than its non-installed (i.e., uncompressed) thickness. The performance of a thermal runaway barrier is measured when it is in its installed (i.e., compressed) state.

[0097] 8. The nonwoven fiber insulation layer has an uninstalled (i.e., uncompressed) thickness in the range of approximately 1.0 mm to less than 8.0 mm, with the lower limit being approximately 1.0 mm, 1.1 mm, 1.2 mm, 1.3 mm, 1.4 mm, 1.5 mm, 1.6 mm, 1.7 mm, 1.8 mm, 1.9 mm, 2.0 mm, 2.1 mm, 2.2 mm, 2.3 mm, 2.4 mm, 2.5 mm, 2.6 mm, 2.7 mm, 2.8 mm, 2.9 mm, and 3.0 mm. A thermal runaway barrier according to any one of Embodiments 1 to 7, which may be 3.1 mm, 3.2 mm, 3.3 mm, 3.4 mm, or 3.5 mm, with an upper limit of approximately 4.0 mm, 4.1 mm, 4.2 mm, 4.3 mm, 4.4 mm, 4.5 mm, 4.6 mm, 4.7 mm, 4.8 mm, 4.9 mm, 5.0 mm, 5.5 mm, 6.0 mm, 6.5 mm, 7.0 mm, 7.5 mm, or 8.0 mm. The uncompressed thickness of the nonwoven fiber insulation layer is always greater than its installation thickness.

[0098] 9. The layer of non-woven fiber heat insulation material has a basis weight ranging from a low value of about 250 g / m 2 to a high value of about 1000 g / m 2 and is the thermal runaway barrier according to any one of Embodiments 1 to 8. Depending on the composition of the thermal runaway barrier, for the gap between adjacent battery cells in the range of about 0.75 mm to about 1.25 mm, the basis weight is about 250 g / m 2 to about 400 g / m 2 (for example, 300 g / m 2 , 350 g / m 2 ) may be desirable. Depending on the composition of the thermal runaway barrier, for the gap between adjacent battery cells in the range of about 0.75 mm to about 2. mm, and up to about, the basis weight is about 300 g / m 2 to about 550 g / m 2 may also be desirable. For the gap between adjacent battery cells in the range of about 2.5 mm to less than 5.0 mm, the basis weight is about 600 g / m 2 to about 1000 g / m[[ID=2)) 2 (for example, about 650 g / m 2 , 700 g / m 2 ,, 750 g / m 2 , 800 g / m 2 , 850 g / m 2 , 900 g / m 2 , 950 g / m 2 , or 1000 g / m 2 e) may be desirable. Desirable results are achieved with a thermal runaway barrier using thermally insulating inorganic particles of irreversibly or permanently expanded vermiculite, where the non-woven fiber heat insulation material layer has a basis weight of about 450 g / m 2 or 550 g / mre 2 for a gap in the range of about 1.50 mm to about 2.5 mm.

[0099] In one embodiment, the thermally insulating inorganic particles are particles of irreversibly or permanently expanded vermiculite, and the layer of non-woven fiber heat insulation material is 450 g / m for a gap installed between adjacent battery cells in the range of about 1.50 mm to about 2.5 mm 2It has a basis weight of . In another embodiment, the insulating inorganic particles are irreversibly or permanently expanded vermiculite particles, and the layer of nonwoven fiber insulation is 550 g / m for gaps placed between adjacent battery cells ranging from about 1.50 mm to about 2.5 mm. 2 It has a basis weight of [amount].

[0100] 10. The nonwoven fiber insulation layer is approximately 250 g / m². 2 ~about 400g / m 2 A thermal runaway barrier according to any one of embodiments 1 to 9, having a basis weight in the range of [specified range].

[0101] In certain embodiments, for example, the insulating inorganic particles are irreversibly or permanently expanded vermiculite particles, and the gap is about 1 mm, then the amount is about 300 g / m². 2 ~400g / m 2 A basis weight within this range may be desirable. If the gap is approximately 2.0 mm, then approximately 800 g / m² is preferable. 2 ~about 1000g / m 2 In some cases, a basis weight within this range may be desirable.

[0102] 11. A thermal runaway barrier according to any one of Embodiments 1 to 10, wherein the insulating inorganic particles are made from, or include at least, particles of one or any combination thereof of materials selected from the group consisting of irreversibly or permanently expanded vermiculite (i.e., vermiculite heated to a temperature and time that causes vermiculite particles to irreversibly or permanently expand to at least 10% to 100% of their expansion capacity, either by pre-expanding before being used to form a barrier or by post-expanding after becoming a nonwoven fiber insulation), irreversibly or permanently expanded perlite (i.e., perlite heated to a temperature and time that causes perlite particles to irreversibly or permanently expand to at least 10% to 100% of their expansion capacity, either by pre-expanding before being used to form a barrier or by post-expanding after becoming a nonwoven fiber insulation), and irreversibly or permanently expanded clay.

[0103] Expanded clay is a lightweight particle or aggregate that can be produced by heating clay in a rotary kiln to approximately 1,200°C (2,190°F). The resulting gas expands the clay through thousands of tiny bubbles formed during heating, creating a honeycomb structure. Because the expanded clay moves in a circular motion within the kiln, it can have a nearly circular or potato-like shape and is available in a variety of sizes and densities. Expanded clay is used in the manufacture of lightweight concrete products (see, for example, the website: https: / / www.archiexpo.com / architecture-design-manufacturer / expanded-clay-aggregate-concrete-23000.html) and other applications. Expanded clay is most commonly known by the brand names LECA (an acronym for lightly expanded clay aggregate) or LIAPOR (porous liac clay), and is also known as Hydroton, and in non-trademark terms as fired clay pebbles, grow rocks, expanded clay, or hydrocorns. It is a small spherical object of fired and expanded clay (see, for example, the website: https: / / www.sciencedirect.com / topics / engineering / expanded-clay-aggregate).

[0104] The thermal runaway barrier may preferably further include other insulating inorganic particles, such as particles of one or any combination of materials selected from the group consisting of inorganic aerogels, xerogels, hollow or porous ceramic microspheres, non-expanding vermiculite, other porous silica, non-expanding perlite, pumice, diatomaceous earth, titania, and zirconia.

[0105] 12. A thermal runaway barrier according to any one of Embodiments 1 to 11, wherein the inorganic fibers of the fiber matrix are selected from the group consisting of alkaline earth silicate fibers, refractory ceramic fibers (RCF), polycrystalline wool (PCW) fibers, basalt fibers, glass fibers, and silicate fibers. Glass fibers and silica fibers typically contain no particles at all or only a small amount of shot particles. PCW typically contains up to 5% shot particles, while alkaline earth silicate (AES) fibers contain up to 60% shot particles when unwashed and as low as about 10-30% when washed.

[0106] 13. A thermal runaway barrier according to any one of Embodiments 1 to 12, wherein the organic binder is in the form of polymer fibers (e.g., PE / PET, PET, FRPET), dry polymer powder (e.g., LDPE, polyamide, epoxy resin powder (3M SCOTCHCAST 265, 3M SCOTCHKOTE 6258)), or liquid binder (e.g., acyl latex, ethylene vinyl acetate (EAF68) latex, silicone, polyurethane, etc.).

[0107] 14. A thermal runaway barrier according to any one of embodiments 1 to 13, wherein a layer of nonwoven fiber insulation is enclosed by an organic encapsulation layer.

[0108] 15. The thermal runaway barrier according to Embodiment 14, wherein the organic encapsulation layer has at least one vent formed through the organic encapsulation layer, the vent being positioned and sized such that expanding gases (e.g., air) contained within the thermal runaway barrier can escape from the organic encapsulation, and the structural integrity of the organic encapsulation layer is maintained when the thermal runaway barrier is compressed during assembly of a battery cell module (e.g., a stack of battery cells) or when the thermal runaway barrier is heated (e.g., during normal operation or when an adjacent battery cell overheats). Each vent may be rectangular (e.g., see Figure 8), circular, elliptical, or any other desired shape, or a combination thereof. One or more or each vent may be in the form of a notch projecting from the side edge of the encapsulation toward the center of the thermal runaway barrier (e.g., see left vent 54 in Figure 8 and vent 54 in Figure 7). Alternatively, one or more vents, or each vent, may be formed on the inside of the side edge of the insulated body, adjacent to the nonwoven insulation (see, for example, the right-side vent 52 in Figure 8 and the vent 52 in Figure 6). In addition, one or more vents, or each vent, may be formed through the insulated layer on only one side of the nonwoven fiber insulation (see the right-side vent 52 in Figure 6) or on both sides (see the left-side vent 52 in Figure 6). It may also be desirable for each vent to be in the form of multiple smaller perforations clustered together (e.g., like a screen, sieve, or colander) to provide a desired outlet opening area.

[0109] 16. The thermal runaway barrier according to Embodiment 14 or 15, wherein the thermal runaway barrier has an upper edge, a lower edge, and opposing side edges, and at least one ventilation hole is located around one or both of the opposing side edges.

[0110] 17. At least one ventilation hole, approximately 2 mm 2 ~about 15mm 2A thermal runaway barrier according to any one of embodiments 14 to 16, providing an exit opening through an organic encapsulation layer having an opening area within the range of [specified range]. It is conceivable that any specific region within this range, or any narrower range within this range, may be desirable.

[0111] 18. A thermal runaway barrier according to any one of embodiments 14 to 17, wherein the organic encapsulation layer is in the form of a continuous layer, a discontinuous layer (e.g., having perforations, through-holes, or porosity that allow gas to penetrate the organic layer), or a combination of both. In addition, the organic layer may be in the form of an organic (e.g., polymer) film, scrim, woven or nonwoven fabric, adhesive (e.g., thermoplastic or hot-melt adhesive) layer, or a combination thereof. An example of an organic layer is a polymer film (e.g., a copolyester polymer film).

[0112] 19. A thermal runaway barrier according to any one of Embodiments 14 to 18, wherein the organic encapsulation layer is a calendered layer, a hot melt coating layer, a spray coating layer, a dip coating layer, or a laminate layer (for example, by using a pressure-sensitive adhesive or other adhesive).

[0113] 20. A thermal runaway barrier according to any one of embodiments 14 to 19, wherein a layer of nonwoven fiber insulation has a periphery, and an organic encapsulation layer is sealed around the periphery.

[0114] 21. A thermal runaway barrier according to any one of Embodiments 1 to 20, wherein the nonwoven fiber insulation layer passes at least V-2 or V-1 level, preferably V-0 level, of the following UL94 V0 flammability test.

[0115] Flammability test The tests were conducted using the UL94 standard, which is a standard for safety testing of the flammability of plastic materials for apparatus and equipment components. The UL94 standard is a plastic flammability standard published by Underwriters Laboratories in the United States. This standard determines whether the material tends to extinguish or spread the flame when the test specimen is ignited. The UL94 standard is consistent with IEC 60707, 60695-11-10 and 60695-11-20 and ISO 9772 and 9773. A 75mm x 150mm sample was exposed to a 2cm, 50W tickrrel burner flame ignition source. The test specimen was placed vertically above the flame with the test flame touching the bottom of the specimen. For each specimen, the time to extinguishment was measured and assigned a V grade. As shown in Table 1 below, Grade V is a measure of the time it takes for the sample to extinguish without burning up to the top of the clamp or dropping molten material that would ignite the cotton indicator.

[0116] [Table 13]

[0117] 22. A thermal runaway barrier according to any one of Embodiments 1 to 21, wherein the thermal insulating inorganic particles include at least particles of an expandable material that have expanded irreversibly or permanently.

[0118] 23. The thermal runaway barrier according to Embodiment 22, wherein the expanded expandable material is irreversibly or permanently expanded to at least about 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, or 90% to 100% of its expansion capacity.

[0119] 24. A thermal runaway barrier according to any one of Embodiments 1 to 23, wherein the insulating inorganic particles include at least particles that are irreversibly or permanently expanded vermiculite particles.

[0120] 25. The thermal runaway barrier according to Embodiment 24, wherein the expanded vermiculite particles are irreversibly or permanently expanded to at least about 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, or 90% to 100% of their expansion capacity.

[0121] 26. A thermal runaway barrier assembly comprising a plurality of thermal runaway barriers according to any one of Embodiments 1 to 25, provided that the plurality of thermal runaway barriers are provided (a) in the form of a stack inside a container (e.g., a cardboard box or other box), (b) arranged end-to-end in series with one main surface of each thermal runaway barrier adhered to the main adhesive surface of a certain length of single-sided or double-sided adhesive tape (if double-sided adhesive tape is used, the main adhesive surface on the opposite side of the tape may be protected with a release liner), or (c) arranged end-to-end in series in the form of tape, with one or more layers of nonwoven fiber insulation of each thermal runaway barrier arranged end-to-end and sandwiched between or otherwise enclosed by two opposing length organic (e.g., polymer) encapsulation layers (e.g., in the form of two opposing films, coatings, fibrous fabrics, etc.).

[0122] Embodiment of a battery cell module 27. Multiple battery cells arranged inside the housing, A plurality of thermal runaway barriers as described in any one of Embodiments 1 to 26, comprising A battery cell module or assembly for an electric vehicle, in which battery cells are arranged in a row or stacked, with one thermal runaway barrier placed between each pair of adjacent battery cells, or between a predetermined number of battery cells.

[0123] Method for manufacturing an embodiment of a battery cell thermal runaway barrier 28. A method for producing a thermal runaway barrier according to any one of Embodiments 1 to 27, comprising forming a layer of nonwoven fiber insulation using a wet process or a dry process.

[0124] 29. To provide thermally insulating inorganic particles that are entirely, largely, or at least contain fumed silica, The method according to Embodiment 28, further comprising arranging insulating inorganic particles so as to be uniformly or evenly distributed throughout or within a layer of nonwoven fiber insulation material.

[0125] 30. To provide additional thermally insulating inorganic particles that are entirely, largely, or at least contain non-expandable expandable particles (e.g., non-expandable expandable particles such as non-expandable vermiculite particles or non-expandable perlite particles), Arranging non-expandable expandable particles so as to be uniformly or evenly distributed throughout or within the entire layer of nonwoven fiber insulation, The method further includes heating non-expandable expandable particles (e.g., expandable particles) to a temperature and time that causes the non-expandable expandable particles to expand irreversibly or permanently, The method according to Embodiment 29, wherein heating is performed before or after the non-expandable expandable particles are placed within the layer of nonwoven fiber insulation.

[0126] 31. The method according to Embodiment 30, wherein heating is performed after non-expandable expandable particles are placed within a layer of nonwoven fiber insulation.

[0127] 32. The method according to Embodiment 30 or 31, wherein heating irreversibly or permanently expands non-expanding expandable particles to at least about 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, or 90% to 100% of their expansion capacity.

[0128] 33. The method according to any one of Embodiments 30 to 32, wherein the non-expandable expandable particles include non-expandable expandable particles (e.g., vermiculite particles, non-expandable perlite particles, or a combination thereof).

[0129] 34. To provide thermally insulating inorganic particles that are entirely, largely, or at least contain irreversibly or permanently pre-expanded expandable particles (e.g., irreversibly or permanently pre-expanded expandable particles of vermiculite or perlite), The present invention further includes arranging insulating inorganic particles so as to be uniformly or evenly distributed throughout or within the entire layer of a nonwoven fiber insulating material, The method according to Embodiment 29, wherein pre-expanded particles are formed by heating non-expandable expandable particles to a temperature and time that causes the non-expandable expandable particles to expand irreversibly or permanently, before the insulating inorganic particles are placed in a layer of nonwoven fiber insulation.

[0130] 35. The method according to Embodiment 34, wherein the pre-expanded expandable particle is an expandable particle that has been irreversibly or permanently expanded to at least about 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, or 90% to 100% of its expansion capacity.

[0131] 36. The method according to Embodiment 34 or 35, wherein the pre-expanded expandable particles include pre-expanded vermiculite particles, pre-expanded perlite particles, or both.

[0132] The present invention can be modified and altered in various ways without departing from its spirit and scope. For example, it is conceivable that particles made from expandable materials can be irreversibly or permanently expanded using microwave heating. It is also conceivable that expandable particles can be expanded more uniformly within a fiber matrix by using microwave energy instead of baking in an oven. Therefore, the present invention is not limited to the foregoing and should be limited by the limitations shown in any of the following embodiments and their equivalents. The present invention can be suitably carried out without any elements not specifically disclosed herein. All patents and patent applications cited above, including those in the background art section, are incorporated into this document as a whole by reference. The following are exemplary embodiments. [Item 1] A thermal runaway barrier positioned between battery cells of a battery assembly and adapted to act at least significantly slow down thermal runaway events within the battery assembly, Inorganic fiber matrix, A layer of nonwoven fiber insulation material comprising: thermal insulating inorganic particles of fumed silica material dispersed within the fiber matrix; and a binder dispersed within the fiber matrix that holds the fiber matrix together; An optional organic encapsulation layer surrounding the layer of the nonwoven fiber insulation material, A thermal runaway barrier comprising an optional inorganic encapsulation layer surrounding the layer of nonwoven fiber insulation material. [Item 2] The fumed silica particles are approximately 100 m 2 / g~about 400m 2 A thermal runaway barrier as described in item 1, having a surface area in the range of / g. [Item 3] The thermal runaway barrier according to item 1 or 2, wherein the layer of nonwoven fiber insulation contains fiber shots in an amount ranging from about 3% to about 60% by weight of the amount of inorganic fibers in the layer of nonwoven fiber insulation. [Item 4] A thermal runaway barrier according to any one of items 1 to 3, wherein the layer of nonwoven fiber insulation contains insulating inorganic particles in an amount ranging from a low value of about 10% by weight to a high value of about 60% by weight of the layer of nonwoven fiber insulation. [Item 5] A thermal runaway barrier according to any one of items 1 to 4, wherein the layer of nonwoven fiber insulation contains an amount of organic binder ranging from a low value of about 2.5% by weight to a high value of about 10.0% by weight of the layer of nonwoven fiber insulation. [Item 6] A thermal runaway barrier according to any one of items 1 to 5, wherein the layer of nonwoven fiber insulation has an installation thickness in the range of approximately 0.5 mm to less than 5.0 mm. [Item 7] The layer of the nonwoven fiber insulation material is approximately 250 g / m². 2 From a low value of approximately 1000g / m 2 A thermal runaway barrier described in any one of items 1 to 6, having a basis weight in the range up to a high value. [Item 8] The layer of the nonwoven fiber insulation material is approximately 250 g / m². 2 ~about 400g / m 2 A thermal runaway barrier according to any one of items 1 to 7, having an incompressible basis weight within the range. [Item 9] A thermal runaway barrier according to any one of items 1 to 8, wherein the thermal insulating inorganic particles further comprises particles of one or any combination of materials selected from the group consisting of inorganic aerogel, xerogel, hollow or porous ceramic microspheres, non-expanding vermiculite, irreversibly or permanently expanded vermiculite, other porous silica, irreversibly or permanently expanded perlite, non-expanding perlite, pumice, expanded clay, diatomaceous earth, titania, and zirconia. [Item 10] A thermal runaway barrier according to any one of items 1 to 9, wherein the layer of nonwoven fiber insulation is enclosed by the organic encapsulation layer. [Item 11] The thermal runaway barrier according to item 10, wherein the organic encapsulation layer has at least one vent formed through the organic encapsulation layer, the vent being positioned and sized such that gas contained within the thermal runaway barrier can escape from the organic encapsulation, and the structural integrity of the organic encapsulation layer is maintained during a thermal runaway event. [Item 12] The thermal runaway barrier according to item 10 or 11, wherein the thermal runaway barrier has an upper edge, a lower edge, and opposing side edges, and the at least one ventilation hole is located around one or both of the opposing side edges. [Item 13] The aforementioned at least one ventilation hole is approximately 2 mm 2 ~about 15mm 2 A thermal runaway barrier according to any one of items 10 to 12, providing an exit opening through the organic encapsulation layer having an opening area in the range of [specified range]. [Item 14] A thermal runaway barrier according to any one of items 10 to 13, wherein the layer of nonwoven fiber insulation has a periphery, and the organic encapsulation layer is sealed around the periphery. [Item 15] A thermal runaway barrier according to any one of items 1 to 14, wherein the layer of nonwoven fiber insulation passes at least level V-2 of the UL94 flammability test. [Item 16] A thermal runaway barrier according to any one of items 1 to 15, wherein the thermal insulating inorganic particles include particles of an expandable material that have expanded irreversibly or permanently. [Item 17] A thermal runaway barrier according to any one of items 1 to 16, wherein the thermal insulating inorganic particles include irreversibly or permanently expanded vermiculite particles. [Item 18] The thermal runaway barrier according to item 17, wherein the expanded vermiculite is irreversibly or permanently expanded to a range of at least about 10% to 100% of its expansion capacity. [Item 19] Multiple battery cells arranged inside the housing, A plurality of thermal runaway barriers as described in any one of items 1 to 18, The aforementioned battery cell module for electric vehicles is arranged in a row with one thermal runaway barrier placed between each pair of adjacent battery cells. [Item 20] A method for producing a thermal runaway barrier according to any one of items 1 to 18, comprising forming a layer of the nonwoven fiber insulation using a wet process or a dry process.

Claims

1. A thermal runaway barrier positioned between battery cells of a battery assembly and adapted to act at least significantly slow down thermal runaway events within the battery assembly, Inorganic fiber matrix, A layer of nonwoven fiber insulation material comprising: thermal insulating inorganic particles of fumed silica material dispersed within the fiber matrix; and a binder dispersed within the fiber matrix that holds the fiber matrix together; It comprises an organic encapsulation layer, The layer of nonwoven fiber insulation is enclosed by the organic encapsulation layer. The organic encapsulation layer has at least one vent formed through the organic encapsulation layer, and the vent is positioned and sized such that gas contained within the thermal runaway barrier can escape from the organic encapsulation layer, and the structural integrity of the organic encapsulation layer is maintained during a thermal runaway event. Thermal runaway barrier.

2. The fumed silica particles are approximately 100 m ２ / g ~ approx. 400m ２ A thermal runaway barrier according to claim 1, having a surface area in the range of / g.

3. The thermal runaway barrier according to claim 1 or 2, wherein the layer of nonwoven fiber insulation contains fiber shots in an amount ranging from about 3% by weight to about 60% by weight of the amount of inorganic fibers in the layer of nonwoven fiber insulation.

4. The thermal runaway barrier according to any one of claims 1 to 3, wherein the layer of the nonwoven fiber insulation material contains thermal insulating inorganic particles in an amount ranging from a low value of about 10% by weight to a high value of about 60% by weight of the layer of the nonwoven fiber insulation material.

5. The thermal runaway barrier according to any one of claims 1 to 4, wherein the layer of nonwoven fiber insulation contains an amount of organic binder ranging from a low value of about 2.5% by weight to a high value of about 10.0% by weight of the layer of nonwoven fiber insulation.

6. The thermal runaway barrier according to any one of claims 1 to 5, wherein the layer of nonwoven fiber insulation material has an installation thickness in the range of about 0.5 mm to less than 5.0 mm.

7. The thermal runaway barrier according to claim 7, wherein the thermal runaway barrier has an upper edge, a lower edge, and opposing side edges, and at least one ventilation hole is located around one or both of the opposing side edges.

8. The thermal runaway barrier according to any one of claims 1 to 7, wherein the thermal insulating inorganic particles include irreversibly or permanently expanded vermiculite particles.

9. Multiple battery cells arranged inside the housing, A plurality of thermal runaway barriers according to any one of claims 1 to 8, comprising The aforementioned battery cell module for electric vehicles is arranged in a row with one thermal runaway barrier placed between each pair of adjacent battery cells.

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