Battery cell thermal runaway barrier

Abstract

A thermal runaway barrier for at least significantly mitigating thermal runaway events within a battery assembly. The thermal runaway barrier primarily comprises a nonwoven fiber thermal insulation monolayer, which includes an inorganic fiber matrix, thermally insulating inorganic particles 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 used to encapsulate the nonwoven fiber thermal insulation.

Description

[0001] The present invention relates to a barrier for at least significantly mitigating thermal runaway events within a battery assembly (e.g., a battery assembly used in an electric vehicle). Background Technology

[0002] Electric or hybrid vehicles (e.g., automobiles) use electric motors that are at least partially powered by batteries. Lithium-ion batteries are commonly used in such applications and are available in three forms: prismatic cells, pouch cells, or cylindrical cells. These batteries are compactly housed within the vehicle to save space. Sometimes, one or more of the battery cells or modules experience thermal runaway events, which can cause many (if not all) of the battery cells or modules to overheat and be destroyed. The industry aims to prevent, stop, or at least significantly mitigate such thermal runaway events.

[0003] Many thermal barrier elements have been developed in the industry that require multiple layers of various inorganic materials to perform such functions (see, for example, U.S. Patent 8,541,126B2).

[0004] The background description provided herein is for the purpose of generally presenting the background of this disclosure. Within the scope of this disclosure described in this background section, the work of the currently named inventors, and aspects of the specification that may not otherwise be considered prior art at the time of filing, are not expressly or implicitly acknowledged as prior art opposing this disclosure. Summary of the Invention

[0005] The inventors have discovered that suitable thermal barrier elements can be used without the need for multiple layers of inorganic non-metallic materials.

[0006] In one aspect of the invention, a thermal runaway barrier is provided, operatively adaptable for placement between cell cells of a battery assembly, and for at least significantly mitigating thermal runaway events within the battery assembly. The thermal runaway barrier comprises or is primarily composed of a nonwoven fiber thermal insulation monolayer, the nonwoven fiber thermal insulation monolayer comprising a fiber matrix of inorganic fibers, thermally insulating inorganic particles dispersed within the fiber matrix, and an adhesive dispersed within the fiber matrix to hold the fiber matrix together. An optional organic encapsulation layer may also be included for encapsulating the nonwoven fiber thermal insulation monolayer.

[0007] In another aspect of the invention, a battery cell module or assembly for an electric vehicle is provided. The battery cell module or assembly includes a plurality of battery cells disposed in a housing and a plurality of thermal runaway barriers according to the invention. These battery cells are arranged in rows or stacks, wherein a thermal runaway barrier is provided 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.

[0008] In another aspect of the invention, a method for preparing a thermal runaway barrier according to the invention is provided, wherein the method includes forming a nonwoven fiber thermal insulation layer using a wet web forming process or a dry web forming process.

[0009] The above description of the invention is not intended to describe every disclosed embodiment or every implementation of the invention. The following description illustrates exemplary embodiments in more detail. Guidance is provided in several places throughout this application by way of a list of embodiments that can be used in various combinations. In each case, the cited list is used only as a representative group and should not be construed as an exclusive list. Attached Figure Description

[0010] The description corresponding to the included figures is included in this description.

[0011] Figure 1 This is a schematic end view of the fiber matrix layer and optional encapsulation layer that can be used in thermal runaway barrier applications.

[0012] Figure 2 This is a schematic side view of a battery module of a battery cell, in which a thermal runaway barrier is positioned between adjacent battery cells.

[0013] Figure 3 It is a schematic top view of the battery pack of the battery module, in which thermal runaway barriers are placed between adjacent battery modules and / or on top of the battery modules.

[0014] Figure 4 This is a photographic perspective view of a thermal runaway barrier encapsulated with an adhesive-backed organic polymer layer that has a release liner and an expansion gas outlet / notch.

[0015] Figure 5 This is a schematic side view of a dry web-forming process for manufacturing a thermal runaway barrier for a battery cell, according to one embodiment of the present invention.

[0016] Figure 6 This is a cross-sectional view of one embodiment of a thermal runaway barrier according to an embodiment of the present invention, showing a plurality of expansion vents formed by an encapsulation membrane.

[0017] Figure 7 This is a cross-sectional view of another embodiment of the thermal runaway barrier according to another embodiment of the present invention, showing a plurality of expansion vents in the form of notches formed by an encapsulation membrane.

[0018] Figure 8This is a top plan view of an additional embodiment of a thermal runaway barrier, which has two different types of expansion vents formed by an encapsulation membrane. Detailed Implementation

[0019] In describing preferred embodiments of the invention, specific terminology will be used for clarity. However, the invention is not intended to be limited to the particular terms chosen so far, and each such term includes all technical equivalents that work similarly.

[0020] As used herein, the terms "preferred" and "ideally" refer to embodiments described herein that provide certain benefits in certain circumstances. However, other embodiments may also be preferred in the same or other circumstances. Furthermore, the description of one or more preferred embodiments does not imply that other embodiments are unavailable, nor is it intended to exclude other embodiments from the scope of the invention.

[0021] As used herein and in the appended claims, unless the context clearly indicates otherwise, the singular forms “a / an” and “the” include plural objects. Thus, by way of example, references to “a / an” or “the” component may include one or more components known to those skilled in the art or their equivalents. Additionally, the term “and / or” means one or all of the listed elements or a combination of any two or more of the listed elements.

[0022] It is important to note that the term "comprising" and its variations are not intended to be limiting when they appear in the appended specification. Furthermore, "a," "an," "the," "at least one," and "one or more" are used interchangeably herein. Relative terms such as left, right, forward, backward, top, bottom, side, upper, lower, horizontal, vertical, etc., may be used herein, and if so, they are derived from the perspective observed in the accompanying drawings. However, these terms are used only for simplicity of description and are not intended to limit the scope of the invention in any way.

[0023] Throughout this specification, references to "one embodiment," "some embodiments," "one or more embodiments," or "implementation" mean that a specific feature, structure, material, or characteristic described in connection with an embodiment is included in at least one embodiment of the invention. Therefore, phrases appearing in various places throughout this specification, such as "in one or more embodiments," "in some embodiments," "in one embodiment," or "in an embodiment," do not necessarily refer to the same embodiment of the invention. Where applicable, trade names are listed in all capital letters.

[0024] The term “and / or” means one or all of the listed elements or any two or more of the listed elements (e.g., preventing and / or dealing with distress means preventing, dealing with, or both dealing with and preventing further distress).

[0025] As used herein, the term “or” is generally used in the sense that it includes “and / or”, unless the context clearly indicates otherwise.

[0026] In addition, in this paper, the numerical range expressed by the endpoints includes all the numerical values ​​contained in that range (for example, 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, 5, etc.).

[0027] “Environmental conditions” refers to 25°C and 101.3 kPa pressure.

[0028] Unless otherwise specified, “average” means average.

[0029] "Continuous" means extending along a given layer across a single uniform area (perforated sheets can be continuous);

[0030] "Cure" refers to exposure to radiation, heating, or any form of physical or chemical reaction that causes hardening or increased viscosity.

[0031] "Discontinuous" means extending along a given layer across multiple discrete regions, which are spaced apart from each other;

[0032] "Size" refers to the longest dimension of a given object or surface.

[0033] "Substantially" means in a significant amount, such as at least 50%, 60%, 70%, 80%, 90%, 95%, 96%, 97%, 98%, 99%, 99.5%, 99.9%, 99.99%, or 99.999%, or 100%.

[0034] "Thickness" refers to the distance between the two opposite sides of a multilayer or multi-layered product.

[0035] A numerical range expressed by endpoints includes all numbers contained within that range with increments commensurate with the accuracy indicated by the endpoints of the defined range (e.g., for a range from 1.000 to 5.000, the increment would be 0.001, and the range would include 1.000, 1.001, 1.002, etc., 1.100, 1.101, 1.102, etc., 2.000, 2.001, 2.002, etc.). 2.100, 2.101, 2.102, etc., 3.000, 3.001, 3.002, etc., 3.100, 3.101, 3.102, etc., 4.000, 4.001, 4.002, etc., 4.100, 4.101, 4.102, etc., 5.000, 5.001, 5.002, etc., up to 5.999) and any range within that range, unless otherwise expressly specified.

[0036] The term “polymer” should be understood to include polymers, copolymers (e.g., polymers formed using two or more different monomers), oligomers and combinations thereof, as well as polymers, oligomers or copolymers that can be formed into miscible blends.

[0037] The examples selected below are merely for further illustration of the features, advantages, and other details of the invention. However, it should be clearly understood that while these examples are for illustrative purposes, they should not be construed as unduly limiting the scope of the invention in terms of the specific ingredients, quantities, and other conditions and details used.

[0038] refer to Figure 1 The fiber matrix layer 10, which can be used in thermal runaway barrier applications, comprises nonwoven inorganic (i.e., nonmetallic) or other forms of heat-resistant fiber insulation, thermally insulating ceramics or other forms of nonmetallic inorganic particles, and organic or inorganic binders. As used herein, nonmetallic means that it is not a metal or metal alloy. Optionally, the fiber matrix layer 10 is encapsulated with an organic polymer layer 12.

[0039] refer to Figure 2 An exemplary battery module 20 includes components of battery cells 22 and a plurality of thermal runaway barriers 24. Each thermal runaway barrier 24 is in the form of a single fiber matrix layer 10, with or without encapsulation 12, and may be fabricated from the exemplary materials described herein. At one or more locations throughout the battery module 20, the thermal runaway barriers 24 may be disposed between adjacent battery cells 22, between groups of cells 22, or both. Typically, the battery module 20 is resting above a cooling plate 26 and a tray 28.

[0040] refer to Figure 3The 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 modules in the module 20 may share the same cooling plate 26 and tray 28. A thermal runaway barrier 24 formed of the exemplary material described herein may be disposed between one or more adjacent battery modules 20, on top of one or more battery modules 20 (see reference numeral 24'), or any combination thereof. The thermal runaway barrier 24 may also be sized to cover the top of all battery modules in the battery pack 20.

[0041] refer to Figure 4 An exemplary thermal runaway barrier 24 comprises a single fibrous matrix layer (not shown) encapsulated with an organic polymer layer 12 covering both sides and the peripheral edges of the fibrous matrix layer. In one embodiment, the main opposing surfaces of the encapsulation layer 12 are coated with an adhesive (e.g., a pressure-sensitive adhesive) protected by corresponding release pads 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 interior of the encapsulation layer 12, rather than causing the encapsulation layer 12 to swell and expand like a balloon, for example, when the air trapped in the encapsulation layer 12 is heated to an elevated temperature (e.g., when the temperature of one or more adjacent battery cells 20 rises).

[0042] refer to Figure 5Conventional dry web fabrication equipment and processes can be used to manufacture the thermal runaway barrier 20 according to the present invention. Examples of such equipment and processes can be found 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.). Such equipment may include a chamber or forming chamber 40 having multiple feeder inlets, including an inlet 42 for feeding any desired combination of fibers, binders, and particles into the chamber 40, and multiple inlets 44, 44', and 44'' for feeding any desired amount or type of filler material into the chamber 40. After the fibers are combined and mixed with other components, the resulting nonwoven fiber material 45 is deposited onto a belt 46 that conveys the material 45 to, through, and out of a baking oven 47, in which the binder is cured, at least... This allows the fiber material 45 to be further processed. The resulting cured nonwoven fiber material 45' is then die-cut, laser-cut, water-jet-cut, or otherwise processed into individual nonwoven fiber layers 10 (not shown), and each nonwoven fiber layer is then processed at encapsulation station 48, for example by laminating a polymer film 12 (not shown) to opposite sides of each layer 10. Optional hot melt adhesives or pressure-sensitive adhesives may be applied to one or both sides of the encapsulation 12 at corresponding spray stations 49 and 49'. A protective release liner (not shown) may then be applied to each adhesive surface.

[0043] refer to Figure 6 One embodiment of the thermal runaway barrier 24 according to the invention includes one or more vents 52 formed by one or two layers of an encapsulating membrane 12. The vents 52 may have any desired shape (e.g., circular, rectangular, elliptical, etc.), and preferably, the vents 52 are formed by a portion of the membrane 12 positioned outside the periphery of the encapsulating fiber layer 10 but still within the periphery of the encapsulation 12, while providing a path for expanding gases (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.

[0044] refer to Figure 7 Another embodiment of the thermal runaway barrier 24 according to the invention includes two vents 54, each vent being in the form of a notch formed by the encapsulation membrane 12. The vents 54 can have any desired shape (e.g., semi-circular, rectangular, semi-elliptical, etc.), and preferably, the notches 54 are formed by a portion of the membrane 12 positioned outside the periphery of the encapsulating fiber layer 10 and extending beyond the periphery of the encapsulation 12, while also providing a path for expanding gases (e.g., air) to escape from the space containing the fiber layer 10. The number, size, and location of these notches 54 can be varied as needed.

[0045] refer to Figure 8 An additional embodiment of the thermal runaway barrier 24 according to the invention includes two different types of vents 52 and 54 formed by encapsulation 12, similar to those described above relative to... Figure 6 and Figure 7 The aforementioned vent.

[0046] Table 1: Test Materials

[0047]

[0048]

[0049] Test methods

[0050] Hot / Cold Side Test 1 (HCST1)

[0051] In an MTS Insight 5kN tensile testing machine (purchased from MTS Insight of Eden Prairie, MN, United States), the bottom platen was heated to 600°C, and the sample was placed on top of it. The upper platen, with the thermocouple embedded in it, was lowered so that the distance between the two plates was 1.6 mm. The increase in cold-side temperature relative to time was recorded (continuously) until 900 seconds (15 minutes) had elapsed.

[0052] Hot / Cold Side Test 2 (HCST2)

[0053] In a 10kN tensile testing machine (purchased from ZWICKROELL of Ulm, Germany), the top platen was heated to 600°C, and the sample was placed on a bottom pressure plate embedded with thermocouples, set to ambient temperature. A heat shield was used to cover the sample to ensure it remained at ambient temperature. The heat shield was then removed, and the upper pressure platen was lowered while maintaining a pressure of 1MPa. The time it took for the sample to reach 150°C (302°F) was recorded and designated as t(150°C).

[0054] Shear strength:

[0055] Follow ASTM 273C and 273M methods. Use a shearing rate of five minutes.

[0056] Thermal conductivity test:

[0057] Thermal conductivity measurements were obtained using a thermal constant analyzer, model TPS 2500S, from Hot in Gothenburg, Sweden. AB Company (Hot) AB of Goteborg, Sweden). Measurements were performed by selecting the isotropic / bulk (Type I) module within the software. A 3.2mm diameter Kapton 5465 sensor (Hot) was used. Measurements should be performed. As specified in the manual, the sample should have a lateral dimension of 1.5 to 2.0 times the sensor radius. The sample thickness should also be equal to or greater than the sensor radius. To ensure the thickness is sufficiently greater than the sensor radius, stack three to four layers of sample on each side of the sensor and apply slight pressure to ensure each layer is in contact with the others.

[0058] The specified parameters are 1) measurement time in seconds and 2) heating power in mW. The sample temperature is input as ambient room temperature. Then, the measurement is performed according to the specifications in the TPS manual.

[0059] Analyze the results by clicking "Calculate" within the software and selecting the "Standard Analysis" option. After measurement, the software presents several graphs, including "Instantaneous" and "Residual" graphs. The instantaneous graph shows the temperature rise of the sensor during the sample heating to up to 200 points. The first pass of the analysis results will start from point 10 and include everything up to point 200 in the instantaneous graph. If the residual graph does not appear to be a randomly scattered distribution of points, a smaller subset of data points is used for analysis. This is done by trimming points from the start and end points of the measurement. Generally, if fewer than 50 points are used in the analysis, the results are unreliable. In addition to meeting the quality requirements of the residual graph, several other numerical requirements are defined, including "Detection Depth (PD)," "Temperature Increase (TI)," "Total Characteristic Time (TCT)," and "Mean Deviation (MD)" as specified in the manual. For these specifications: PD must be less than the sample thickness, TI must be between 0.4 K and 4.0 K, TCT must be between 0.33 and 1.0, and MD must be on the order of 10⁻⁴ or better. If these five criteria are not met, adjust the heating power and measurement time. Repeat these settings until accurate measurements are achieved, where accuracy is defined by meeting all numerical requirements shown in the manual. Measure and record the thermal conductivity value for the test sample in W / m·K.

[0060] Examples 1 to 8 (EX1-EX8) and Comparative Examples 1 to 2 (CE1-CE2)

[0061] For Examples 1, 3, and 5 through 7, the weight percentage combinations of short fibers (as shown in Table 2) were weighed and premixed by hand before being placed on the feed belt. The fiber material was processed by an air-laid processor (i.e., top-feeded), as disclosed in U.S. Patent 7,491,354, in which the fibers were opened and dispersed into the airflow and then collected on a screen belt. Details of such air-laid processing equipment and methods for forming air-laid webs using such equipment can be found 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.). Filler, by weight percentage (as shown in Table 2), was fed from the top or side into the chamber or forming box of the air-laid processor. The filler was uniformly distributed into the web using a volume feeder coupled to a pneumatic horn. The sample was then fed out at a speed of 1.1 m / min through a forced-ventilation convection oven at 143.3 °C (290 °F).

[0062] For Examples 2 and 4, the method described in Example 1 of U.S. Patent 5,869,010 (Langer) was followed. The assembled samples contained the fibers and fillers in the weight percentages shown in Table 2, instead of the materials shown in U.S. Patent 5,869,010.

[0063] For Example 8, Example A of U.S. Patent 9,399,864 (Samama et al.) was followed with significant modifications. An aerogel slurry was prepared by adding 400 g of Barlox 12 (obtained from the Lonza Group of Basel, Switzerland) to 379 liters (100 gallons) of water at 43°C (110°F). The slurry was mixed. 200 g of Foamaster 111 (obtained from the BASF Group of Ludwigshafen, Germany) was added, and the slurry was mixed. EAF68 (as shown in Table 2) was added by weight percentage and mixed. Then AG (as shown in Table 2) was added by weight percentage and mixed. The slurry was mixed for 15 minutes, and then 200 g of MOJO MP9307C was added and mixed. Fiber pulp was prepared by adding 717 g of Microstrand 110X-481 (obtained from John Manville of Denver, CO, United States) to 2271 liters (600 gallons) of water. The pulp was pulped at 500 rpm for 60 seconds. T255 (by weight percentage, as shown in Table 2) was added and the pulp was pulped at 500 rpm for 30 seconds. An additional 1136 liters (300 gallons) of water was then added to the pulp. 757 liters (200 gallons) of fiber pulp was mixed with 379 liters (100 gallons) of aerogel pulp, and SW+ (by weight percentage, as shown in Table 2) was incorporated. The combined pulp was processed on a paper machine.

[0064] Table 2: Sample Compositions (by weight)

[0065] SW+ LDM T255 EAF68 PA AG K1 WDS EXP EX1 20 20 16 0 4 40 0 0 0 EX2 0 62 0 8 0 0 30 0 0 EX3 20 20 16 0 4 0 0 40 0 EX4 0 52 0 8 0 0 0 0 40 CE1 35 35 30 0 0 0 0 0 0 EX5 15 15 30 0 0 40 0 0 0 CE2 92 0 8 0 0 0 0 0 0 EX6 72 0 8 0 0 20 0 0 0 EX7 52 0 8 0 0 40 0 0 0 EX8 59.5 0 2.5 8 0 30 0 0 0

[0066] The samples were tested for HCST1, and the results are shown in Table 3.

[0067] Table 3: Hot / Cold Side Temperature Test Results (Basis Weight = 600 gsm), in degrees Celsius (°C)

[0068]

[0069]

[0070] Examples 9 to 34 (EX9-EX34) and Comparative Examples 3 to 8 (CE3-CE8)

[0071] Following the general procedure for preparing fiber sheets described in U.S. Patent Application 2010 / 0115900, with material substitutions as shown in Table 4, 3 liters of tap water (18°C) and 60 grams (g) of inorganic fibers were added to a GT800 classic blender (Rotor Lips Ltd, Uetendorf, Switzerland) and washed until the bulk content was less than 50% by weight. The blender was run at low speed for five seconds. The resulting slurry was rinsed into an RW16 mixing vessel equipped with a paddle mixer using 1 liter of tap water (18°C). The slurry was diluted with an additional 1 liter of tap water (18°C). The diluted slurry was mixed at a medium speed to maintain solid suspension. Add defoamer (trade name "FOAMASTER 111" (0.3 g), available from Henkel, Edison, NJ) and ethylene-vinyl acetate terpolymer latex (trade name "ATRFLEX 600BP" (6.0 g, 55 wt% solids), available from Air Products). Add the flocculant dropwise as shown in Table 4. Then add the thermal insulation particles as shown in Table 4. Increase the mixer speed and mix for 1 to 5 minutes. Remove the paddle mixer and pour the slurry into a 20 cm × 20 cm (8 inch × 8 inch) sheet forming apparatus (Williams Apparatus Co., Watertown, NY, United States) and drain. Roll the surface of the drained sheet with a rolling pin to remove excess water. The sheet was then pressed between blotting papers under a surface pressure of 90-97 kPa (13-14 psi) for five minutes. The sheet was then dried in a forced-ventilation oven at 150°C for 10-15 minutes and equilibrated overnight while exposed to ambient atmosphere. The thickness and basis weight of the samples were measured at a constant pressure of 4.9 kPa and recorded in Table 5. For Examples 15 to 25 (EX15-EX25), the vermiculite material used in these samples was either preheated to permanently pre-expand the vermiculite before sample preparation or post-heated under specific time and temperature conditions after sample preparation to permanently post-expand the vermiculite. For EX21, the vermiculite was preheated at 300°C for 6 hours before sample assembly. For EX22 and EX23, the vermiculite was heated at 450°C for 30 minutes after sample assembly. For EX24, the vermiculite was preheated at 500°C for 30 minutes before sample assembly. For EX25, EX33 and EX34, the vermiculite in the samples was preheated at 1000°C for 30 minutes before sample assembly.

[0072] Table 4: Sample Compositions (by weight)

[0073] SW+ sum EAF68 VERM1 EXVERM PERL EXPERL CE3 95 0 5 0 0 0 0 CE4 90 0 10 0 0 0 0 CE5 90 0 10 0 0 0 0 CE6 90 0 10 0 0 0 0 CE7 90 0 10 0 0 0 0 CE8 90 0 10 0 0 0 0 EX9 50 0 5 45 0 0 0 EX10 50 0 5 45 0 0 0 EX11 50 0 5 45 0 0 0 EX12 50 0 5 45 0 0 0 EX13 50 0 5 45 0 0 0 EX14 50 0 5 45 0 0 0 EX15 0 50 5 0 45 0 0 EX16 0 50 5 0 45 0 0 EX17 0 50 5 0 45 0 0 EX18 0 50 5 22.5 22.5 0 0 EX19 65 0 5 0 30 0 0 EX20 65 0 5 0 30 0 0 EX21 50 0 5 0 45 0 0 EX22 50 0 5 0 45 0 0 EX23 50 0 5 0 45 0 0 EX24 50 0 5 0 45 0 0 EX25 50 0 5 0 45 0 0 EX26 0 23 8 0 0 0 69 EX27 0 23 8 0 0 0 69 EX28 0 23 8 0 0 0 69 EX29 0 47 6 0 0 0 47 EX30 0 22 6 0 0 0 72 EX31 0 70 5 0 0 25 0 EX32 0 20 5 0 0 75 0 EX33 65 0 5 0 30 0 0 EX34 65 0 5 0 30 0 0

[0074] The samples were subjected to HCST2 testing, and the results are shown in Table 5.

[0075] Table 5: Hot / Cold Side Temperature Test Results

[0076]

[0077] Example 35 (EX35)

[0078] The PP was laminated onto the sample assembled as in Example 5. The samples were manually hot-pressed on both sides at 132°C (270°F) and 200 kPa. The edges were manually sealed using a pulse sealing machine at 149°C (300°F), with heating for 2 seconds and cooling for 10 seconds, all steps performed under a compressive force of 524 kPa (76 psi). The PP film thickness was 0.02 mm (1 mil). Shear strength tests were performed on 600 gsm samples, and the results are shown in Table 6.

[0079] Example 36 (EX36)

[0080] Hot melt adhesive H2345 was applied to the sample of Example 35 using a Nordson Altablue Gridmelter with a 15.24 cm (6 inch) meltblown adhesive mold. The adhesive was heated to 193 °C (380 °F) and sprayed onto the web at a pressure of 206.8 kPa (30 psi) and a pump speed of 20 RPM. Shear strength tests were performed on 600 gsm samples, and the results are shown in Table 6.

[0081] Example 37 (EX37)

[0082] Using an ACCUSPRAY ONE spray gun system with PPS from 3M Inc. in St. Paul, Minnesota, USA, FB spray coating was applied to the samples assembled as in Example 35. The samples were manually coated on one side and then flipped to coat the other side. Shear strength tests were performed on 600 gsm samples, and the results are shown in Table 6.

[0083] Example 38 (EX38)

[0084] PKHH phenoxy resin, obtained from Gabriel Performance Products of Akron, OH, United States, was dissolved in a 50% solution of methyl ethyl ketone (MEK) to form an adhesive. The MEK was evaporated at room temperature for 60 minutes. Two adhesive coatings were applied to one side of a 0.076 mm (3 mil) PET film obtained from DuPont of Wilmington, DE, United States. Two adhesive coatings were also applied to one side of another 0.076 mm (3 mil) PET film. The thickness of the adhesive coatings was 0.036 mm (1.4 mil). The adhesive-coated PET sample films were placed on the top and bottom sides of the sample assembled as in Example 5. Shear strength tests were performed on 600 gsm samples, and the results are shown in Table 6.

[0085] Table 6: Test Results of Encapsulated Samples

[0086]

[0087]

[0088] Examples 39 to 40 (EX39 to EX40)

[0089] Samples were assembled using the materials shown in Table 7, following the procedures described in Examples 9 through 16. The thickness and basis weight of the samples were measured at a constant pressure of 4.9 kPa and recorded in Table 8. The samples were subjected to the HCST2 test, and the results are shown in Table 8.

[0090] Table 7: Sample Compositions (by weight)

[0091] SW+ EAF68 VERM2 VERM3 EX39 50 5 45 0 EX40 50 5 0 45

[0092] Table 8: Hot / Cold Side Temperature Test Results

[0093]

[0094] Examples 41 to 57 (EX41 to EX57)

[0095] The combination of short fibers was weighed by basis weight (as shown in Table 9) and processed by an air-laid web forming machine. Details of the apparatus and the method for forming air-laid webs using this apparatus 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 short fibers were then processed again by the air-laid web forming machine, and fumed silica filler was fed directly into the chamber of the machine by basis weight (as shown in Table 2). The filler was uniformly distributed into the web using a screw feeder. The web was then fed through a forced-draft convection oven at 148.89°C (300°F) at a speed of 0.25 m / min to 1.5 m / min. The sample thickness ranged from 0.5 mm to 15 mm.

[0096] The web was then densified to the specified gap thickness using a hot press. A PTFE-coated glass fiber fabric sheet (obtained from McMaster-Carr of Elmhurst, IL. United States) was placed on either side of the sample, which was then positioned between two hot plates maintained at 148.89°C (300°F). Pressure was applied for 30 to 120 seconds to activate the bicomponent fibers (T255). The densified sample was then immediately placed between the two plates and maintained under pressure at room temperature for 30 to 120 seconds to set the web to the desired thickness.

[0097] Table 9: Sample Compositions (gsm)

[0098] SW+ T255 FS EX41 256 64 80 EX42 192 48 160 EX43 128 32 240 EX44 384 96 160 EX45 288 72 320 EX46 192 48 480 EX47 640 160 200 EX48 480 120 400 EX49 480 120 400 EX50 480 120 400 EX51 480 120 400 EX52 480 120 400 EX53 480 120 400 EX54 320 80 600 EX55 768 192 240 EX56 576 144 480 EX57 384 96 720

[0099] The 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, with the fiberglass fabric sheet removed. The plate pressure calibration was 0.002 psi (13.790 Pascals).

[0100] Table 10: Hot / Cold Side Temperature Test Results

[0101]

[0102]

[0103] The density of a 1000 gsm sample containing 40% fumed silica was calculated by dividing the actual basis weight (gsm) by the actual thickness (mm) (shown in EX48-EX53). Table 11 shows the density and cold-side temperature recorded after 3600 seconds of HSCT2 testing for EX48-EX53. The table is organized in ascending order by the measured cold-side temperature.

[0104] Table 11: Density and Cold Side Temperature

[0105] density cold side temperature (gsm / mm) ℃ EX49 472 180.9 EX51 241 141.7 EX53 120 140.2 EX52 153 137.3 EX50 329 134.6 EX48 265 130.8

[0106] Thermal conductivity tests were performed and the results are shown in Table 12.

[0107] Table 12: Thermal conductivity test results

[0108]

[0109]

[0110] Surprisingly, fumed silica has been found to have a higher thermal conductivity than silica aerogels. It is believed that the thermal conductivity of nonwoven fiber thermal insulation (i.e., fiber matrix) without fumed silica particles is lower than that of the same fiber matrix with fumed silica particles.

[0111] Additional Implementation Plan

[0112] Battery cell thermal runaway barrier implementation plan

[0113] 1. A thermal runaway barrier operatively adapted (i.e., designed, configured, shaped, and / or sized) or otherwise adapted to be disposed between adjacent battery cells (e.g., prismatic battery cells or pouch-type battery cells) of a battery module or assembly (i.e., a series of battery cells stacked in a row), such as a battery module or assembly for supplying power to an electric motor (e.g., an electric motor as used in an electric vehicle or hybrid vehicle), and for preventing, stopping, or at least significantly mitigating thermal runaway events within or between adjacent battery modules or assemblies, the thermal runaway barrier consisting primarily of or only of the following:

[0114] Dry- or wet-laid nonwoven fiber thermal insulation monolayers (e.g., in the form of pads, sheets, tapes, or three-dimensional thin-walled structures) comprising a fiber matrix of ceramic or other forms of nonmetallic (i.e., not metals, metal alloys, or metal composites) inorganic fibers, and thermally insulating ceramic or other forms of nonmetallic (i.e., not metals, metal alloys, or metal composites) inorganic particles (these inorganic particles are uniformly, consistently, substantially, or otherwise integrated throughout the manufacturing process or dispersed in the fiber matrix to a degree permissible by the manufacturing process (e.g., a small amount of particle settling may occur at the bottom of the pad in both dry-laid and wet-laid processes)). (internal), and organic or inorganic binders (e.g., organic or inorganic binder fibers needle-punched, sewn, or otherwise mechanically wound into a fiber matrix to hold the fiber matrix together, etc.), the organic or inorganic binder being uniformly, consistently, substantially, or otherwise dispersed throughout the manufacturing process or to a degree permissible by the manufacturing process within the fiber matrix to bond the inorganic filler particles and inorganic fibers together, or otherwise hold the fiber matrix together before being installed between battery cells, for a duration required to withstand at least the required degree of handling (e.g., during encapsulation); and

[0115] An optional organic encapsulation layer (e.g., polymer, paper, etc.) (e.g., one or more opposing interlayers, each in the form of a film, coating, organic fiber nonwoven or woven fabric, etc.) encapsulates all, most or part of at least one or two main surfaces, and preferably also encapsulates all, most or part of the outer periphery of the nonwoven fiber thermal insulation monolayer, to prevent or significantly reduce the shedding or loss of inorganic fibers or particles from the encapsulated nonwoven fiber thermal insulation monolayer.

[0116] The reduction in inorganic fiber or particle loss is significant when the amount of inorganic fiber or particle loss is less than 10%, 5%, or 1% of the original fiber or particle content of the nonwoven fiber thermal insulation layer. The thinner the organic encapsulation layer (i.e., the lower the organic content of the barrier), the better the thermal / cold test results.

[0117] The thermal runaway barrier of the present invention can also be used between battery modules or components.

[0118] According to the present invention, inorganic binders, organic binders, or combinations thereof can be useful, and may include, for example, those disclosed in US 8,834,759. Examples of inorganic binders that can be used in dry or wet web-forming fiber processing may include silicone particles that convert to fusible silica upon heating. Organic-inorganic hybrid binders are also useful, such as, for example... MQ 803 TF is a co-hydrolysis product of tetraalkoxysilane (Q unit) and trimethylalkoxysilane (M unit). The chemical structure of MQ 803 TF can be viewed as a three-dimensional network of polysilicic acid units, which are capped with trimethylsilyl groups. Some residual ethoxy and hydroxyl functionalities exist. The average molecular weight can be precisely controlled by the ratio of M units to Q units. This ratio is crucial for… For the MQ 803 TF, it is approximately 0.67.

[0119] Exemplary binder fibers include bicomponent core-sheath polymer fibers used in dry web forming processes. In wet web forming processes, ethylene vinyl acetate latex dispersion binders, bicomponent 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 thermal insulation material. Combinations of organic and inorganic binders can also be used.

[0120] As used herein, the term "composed of only" indicates that the claimed thermal runaway barrier covers only structures containing the elements described herein.

[0121] As used herein, the term "mainly composed of..." indicates that the claimed thermal runaway barrier is capable of exhibiting the desired thermal insulation properties by using only the stated features / elements, without the need for additional layers of thermal insulation material. For example, the thermal runaway barrier of the present invention does not require the inclusion of another layer of other thermal insulation material (e.g., woven or nonwoven fabrics of inorganic fibers). Therefore, with regard to the statement "mainly composed of...", if a third-party thermal runaway barrier (e.g., a competitor's) includes all the features / elements of the claims of the present invention, as well as one or more additional features / elements not listed in the claims (e.g., additional layers of inorganic fibers), then the third-party thermal runaway barrier is considered to be covered by the claims if such additional features / elements cannot determine whether the thermal runaway barrier will exhibit the desired thermal insulation properties.

[0122] As used in this article, the term “inorganic” refers to ceramics or other non-metallic (i.e., not metals, metal alloys or metal composites) inorganic materials.

[0123] Thermal runaway is a phenomenon where a battery cell experiences an exothermic chain reaction, leading to an uncontrollable rise in the cell's temperature. Among other causes, exothermic chain reactions can be caused by factors such as overheating of the battery cell, overvoltage of the battery cell, and mechanical puncture of the battery cell.

[0124] "Thermal runaway" refers to the phenomenon where thermal runaway of a battery cell leads to thermal runaway of the remaining battery cells in a battery pack or system.

[0125] A "thermal runaway event" refers to a chain reaction in which one battery cell in a battery cell container overheats, causing adjacent battery cells to overheat and potentially leading to an explosion or fire, until the number of overheated battery cells reaches a critical point, resulting in the destruction of all or more of the battery cells in the module or its components. Factors that can cause battery cell overheating include: physical damage, application of overvoltage, and overheating (internal short circuit within the battery cell).

[0126] As the energy density of a battery cell increases, the temperature at which a battery cell begins to fail (e.g., from at least losing its efficiency or becoming inoperable to ignition, combustion, or explosion) decreases. Similarly, as the energy density of a battery cell decreases, the temperature at which a battery cell begins to fail increases. For example, with a controlled ramp-up of temperature, NMC811 batteries tend to begin to fail or even explode when the temperature reaches approximately 120°C to 130°C, while NMC622 batteries begin to fail or even explode when the temperature reaches approximately 180°C. For battery cells with lower energy densities (e.g., NMC532 and NMC433 battery cells), the corresponding temperatures are higher. For physically larger battery cells or when temperatures rise rapidly, thermal runaway through the battery cell can cause local temperatures to take longer to reach a critical point. It is believed that this thermal runaway effect can result in a slightly higher actual temperature at which a battery cell begins to fail or explode. The thermal runaway barrier of the present invention may be necessary to prevent adjacent batteries from reaching temperatures in the range of approximately 130°C to approximately 150°C.

[0127] As used in this article, “preventing” thermal runaway events means preventing the overheating of a single battery cell from causing overheating of adjacent battery cells. This barrier is considered to prevent thermal runaway events when adjacent battery cells do not reach temperatures above 130°C, 135°C, 140°C, 145°C, or 150°C.

[0128] As used in this article, a “stop” thermal runaway event refers to a situation where the overheating of a battery cell causes only adjacent battery cells (i.e., three, two, or even just one battery cell on either side of the overheated battery cell) to overheat, and the remaining battery cells in the battery module or assembly do not overheat.

[0129] As used herein, a “mitigated” thermal runaway event means that the thermal runaway event is mitigated for at least a sufficiently long time to allow persons near the battery module or assembly (e.g., occupants inside the passenger compartment of an electric vehicle) to escape to a safe distance away from the battery module or assembly before being harmed by the thermal runaway event. Once a battery cell fails (e.g., catches fire or overheats to the point of being unable to function properly) and there are thermal barriers between the battery cells, the time for any adjacent battery cell to propagate the fault (e.g., fire or overheating) is at least greater than 5 minutes, and preferably greater than 10 minutes or even 20 minutes.

[0130] Inorganic particles can be solid, hollow, or contain multiple pores. Such particles can include, for example, unexpanded expandable material particles, irreversibly or permanently expanded expandable materials (e.g., expandable materials), diatomaceous earth, inorganic aerogel materials, porous ceramic materials (e.g., silica), irreversibly or permanently expanded perlite minerals, hollow ceramics, or otherwise inorganic (e.g., glass) microspheres. Such porous inorganic particles, such as those found, for example, in irreversibly or permanently expanded vermiculite, are particularly desirable. Irreversible or permanently expanded perlite mineral particles also contain pores, but perlite minerals are harder and less compressible than vermiculite minerals. Silica-based and other aerogel particles also contain pores.

[0131] As used herein, irreversibly or permanently 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 the particles irreversibly or permanently expand to at least 10% and at most 100% of their expandability, or are pre-expanded before being used to form a thermal runaway barrier, or are post-expanded after being incorporated into a nonwoven fiber thermal insulation monolayer.

[0132] Expandable particles (e.g., vermiculite particles) can be permanently expanded by overheating the particles beyond their reversible point (e.g., in the range of about 350°C to about 1000°C for vermiculite). Such permanently expanded particles (e.g., vermiculite particles) can have an expanded accordion or worm-like structure that, compared to the same particles in their unexpanded state, more readily breaks down into smaller particles due to its elongated geometry, lower density, and lower mechanical stability. As the heating temperature increases, the degree of permanent expansion of the particles increases (i.e., the particles can become larger and / or longer). It is also possible to use vermiculite that has been permanently expanded by chemical treatment methods (see, for example, "Chemical Exfoliation of Vermiculite and the Production of Colloidal Dispersions", GF.Walker, WG.Garrett, (Science) April 21, 1967: Vol. 156, No. 3773, pp. 385-387, DOI: 10.1126 / science.156.3773.385; and https: / / science.sciencemag.org / content / 156 / 3773 / 385.abstract).

[0133] Because they are more prone to splitting in their expanded state, post-expansion of the expanded particles is expected after the unexpanded expanded particles have been incorporated into the nonwoven fiber thermal insulation. Even with mild processing to prevent them from splitting substantially, it is believed that incorporating pre-expanded expanded particles into the nonwoven fiber thermal insulation can still cause the expanded particles to become oriented in the planes of the insulation (i.e., the x-axis, y-axis, and / or between). For example, with pre-expanded vermiculite particles, elongated particles may become generally aligned with the fibers in the longitudinal or downstream direction (i.e., the y-axis) of the nonwoven fiber thermal insulation, rather than in the thickness direction (i.e., the z-axis).

[0134] Conversely, when post-expanded (i.e., after preparing nonwoven fiber thermal insulation with unexpanded expanded particles), the expanded expanded particles are not primarily oriented in the plane of the insulation. Compared to the same particles in their expanded state, unexpanded expanded particles typically have a more uniform structural geometry (i.e., an aspect ratio closer to 1). This more uniform structural geometry is believed to be less likely to be affected by fiber alignment during the formation of the nonwoven fiber thermal insulation. As a result, post-expanded expanded particles are more likely to be isotropically oriented within the nonwoven fiber thermal insulation. For example, with respect to post-expanded vermiculite particles, elongated particles may become 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 in their off-axis directions. This difference in orientation between pre-expanded and post-expanded particles is believed to be caused by the more uniform structural geometry of the unexpanded particles compared to their expanded state.

[0135] 2. The thermal runaway barrier according to embodiment 1, wherein the amount of inorganic fiber contained in the nonwoven fiber thermal insulation layer is in the range of about 15% to 19% by weight to about 70%, 75%, 80%, 85% or 90% by weight.

[0136] 3. The thermal runaway barrier according to embodiment 1 or 2, wherein the amount of fiber particles contained in the nonwoven fiber thermal insulation layer is in the range of about 3% by weight to at most about 60% by weight of the amount of inorganic fibers in the nonwoven fiber thermal insulation layer.

[0137] In one embodiment, without the addition of insulating particles, the inorganic fiber content in dry-laid insulation is 95.2% by weight, and in wet-laid insulation it is 95.5% by weight. At the lowest level of insulating particle (e.g., aerogel particles) loading, the inorganic fiber content is 72% by weight for both dry-laid and wet-laid insulation. For dry-laid nonwoven fiber thermal insulation, the fibers are open (i.e., large clumps of fiber are separated and become less dense), which removes some loose particles. For wet-laid nonwoven fiber thermal insulation, the fibers are wet-cleaned, which removes more loose particles than the dry-laid opening process. Approximately 40% loose particles are present in uncleaned SuperWool Plus from Morgan, representing an actual fiber material content of 19%–43% in nonwoven fiber thermal insulation. For nonwoven fiber thermal insulation, a fiber content ranging from approximately 10% to at most approximately 80% may be required. Lower fiber content will require higher amounts of organic binder. Other additives may be included (e.g., flame retardant materials, heat-absorbing materials, infrared reflective materials, etc.).

[0138] 4. The thermal runaway barrier according to any one of embodiments 1 to 3, wherein the amount of thermally insulating inorganic particles contained in the nonwoven fiber thermal insulation layer is in the range from as low as about 10 wt%, 15 wt%, 20 wt%, 25 wt%, 30 wt%, or 35 wt% to at most about 40 wt%, 45 wt%, 50 wt%, 55 wt%, or 60 wt%. For example, a particle content of up to 60% can be obtained using a dry web forming process, and a particle content of up to 50% can be obtained using a wet web forming process.

[0139] 5. The thermal runaway barrier according to any one of embodiments 1 to 4, wherein the amount of organic binder contained in the nonwoven fiber thermal insulation layer is as low as about 2.5% by weight, 3.0% by weight, 3.5% by weight, 4.0% by weight, 4.5% by weight, or 5.0% by weight in the nonwoven fiber thermal insulation layer.

[0140] The range is from 5.5 wt%, 6.0 wt% or 6.5 wt% to at most about 7.0 wt%, 7.5 wt%, 8.0 wt%, 8.5 wt%, 9.0 wt%, 9.5 wt%, or 10.0 wt%.

[0141] 6. The thermal runaway barrier according to any one of embodiments 1 to 5, wherein the installed (i.e., compressed) thickness of the nonwoven fiber thermal insulation layer is in the range of about 0.5 mm to at most less than 5.0 mm. Specifically, the installed (i.e., compressed) thickness may be in the range of about 0.5 mm to at most about 2.5 mm, wherein the lower limit may be 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 the upper limit may be 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 even be as high as approximately 2.6 mm, 2.7 mm, 2.8 mm, 2.9 mm, 3.0 mm, 3.1 mm, 3.2 mm, 3.3 mm, 3.4 mm, 3.5 mm, 3.6 mm, 3.7 mm, 3.8 mm, 3.9 mm, 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, or less than 5.0 mm. The installation thickness of this nonwoven fiber thermal insulation layer is almost always less than its uninstalled (i.e., uncompressed) thickness. The performance of the thermal runaway barrier is measured when it is in its installed (i.e., compressed) state.

[0142] 7. The thermal runaway barrier according to any one of embodiments 1 to 6, wherein the uninstalled (i.e., uncompressed) thickness of the nonwoven fiber thermal insulation layer is in the range of about 1.0 mm to at most 8.0 mm, wherein the lower limit may be about 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, or 2.5 mm. The uncompressed thickness of this nonwoven fiber thermal insulation layer is approximately 2.6mm, 2.7mm, 2.8mm, 2.9mm, 3.0mm, 3.1mm, 3.2mm, 3.3mm, 3.4mm, or 3.5mm, with an upper limit of approximately 4.0mm, 4.1mm, 4.2mm, 4.3mm, 4.4mm, 4.5mm, 4.6mm, 4.7mm, 4.8mm, 4.9mm, 5.0mm, 5.5mm, 6.0mm, 6.5mm, 7.0mm, 7.5mm, or 8.0mm. The uncompressed thickness of this nonwoven fiber thermal insulation layer is almost always greater than its installed thickness.

[0143] 8. The thermal runaway barrier according to any one of embodiments 1 to 7, wherein the basis weight of the nonwoven fiber thermal insulation layer is as low as about 250 g / m². 2 Up to approximately 1000g / m 2Within this range. Depending on the composition of the thermal runaway barrier, a basis weight of approximately 250 g / m³ may be required for the gap between adjacent cell cells ranging from about 0.75 mm to at most about 1.25 mm. 2 Approximately 400g / m 2 (For example, 300g / m 2 350g / m 2 Within the range of ), depending on the composition of the thermal runaway barrier, a basis weight of approximately 300 g / m² may be required for the gap between adjacent cell cells in the range of approximately 0.75 mm to approximately 2.5 mm. 2 Up to approximately 550g / m 2 Within this range, and for gaps between adjacent battery cells ranging from approximately 2.5 mm to at most less than 5.0 mm, a basis weight of approximately 600 g / m² may be required. 2 Up to approximately 1000g / m 2 Within the range (e.g., approximately 650 g / m³) 2 700g / m 2 750g / m 2 800g / m 2 850g / m 2 900g / m 2 950g / m 2 Or 1000g / m 2 The desired results have been achieved using thermally runaway barriers made of irreversibly or permanently expanded vermiculite thermal insulating inorganic particles, where the basis weight of nonwoven fiber thermal insulation is approximately 450 g / m² for gaps ranging from 1.50 mm to at most about 2.5 mm. 2 Or 550g / m 2 .

[0144] In one embodiment, the thermally insulating inorganic particles are irreversibly or permanently expanded vermiculite particles, and the basis weight of the nonwoven fiber thermal insulation layer is 450 g / m² for mounting gaps between adjacent battery cells ranging from about 1.50 mm to at most about 2.5 mm. 2 In another embodiment, the thermally insulating inorganic particles are irreversibly or permanently expanded vermiculite particles, and the basis weight of the nonwoven fiber thermal insulation layer is 550 g / m² for mounting gaps between adjacent battery cells ranging from about 1.50 mm to about 2.5 mm. 2 .

[0145] 9. The thermal runaway barrier according to any one of embodiments 1 to 8, wherein the basis weight of the nonwoven fiber thermal insulation layer is about 250 g / m². 2 Up to approximately 400g / m 2 Within the range.

[0146] For example, in a particular implementation, when the thermally insulating inorganic particles are vermiculite with a gap of about 1 mm, approximately 300 g / m³ may be required. 2 Up to 400g / m 2 Basis weight within the range. When using aerogel particles with a spacing of approximately 1 mm, approximately 250 g / m³ may also be required. 2 The basis weight. When the gap is about 2.0 mm, it may require about 800 g / m. 2 Up to approximately 1000g / m 2 Basis weight within the range.

[0147] 10. A thermal runaway barrier according to any one of embodiments 1 to 9, wherein the thermally insulating inorganic particles are prepared from or comprise at least of particles selected from one or any combination of the following groups: inorganic (e.g., titanium dioxide, zirconium oxide, and / or silica) aerogels, degels, hollow or porous ceramic (e.g., glass, alumina, etc.) microspheres (e.g., bubbles, foam spheres, beads, etc.), unexpanded vermiculite, and irreversibly or permanently expanded vermiculite (i.e., vermiculite particles that have been heated to a certain temperature and sustained for a period of time, causing the vermiculite particles to irreversibly or permanently expand to at least 10% and at most 100% of their expandability). (or by pre-expansion before being used to form a barrier, or by post-expansion after being in a nonwoven fiber thermal insulation monolayer), fumed silica and other forms of porous silica, irreversibly or permanently expanded perlite (i.e., perlite that has been heated to a certain temperature and heated for a period of time, causing the perlite particles to irreversibly or permanently expand to at least 10% and at most 100% of their expandability, or by pre-expansion before being used to form a barrier, or by post-expansion after being in a nonwoven fiber thermal insulation monolayer), unexpanded perlite, pumice, irreversibly or permanently expanded clay, diatomaceous earth, titanium dioxide and zirconium oxide.

[0148] Expanded clay is a lightweight particle or aggregate that can be prepared by heating clay to approximately 1,200°C (2,190°F) in a rotary kiln. The generated gas causes the clay to expand through thousands of tiny bubbles formed during heating, creating a honeycomb structure. Due to its circumferential movement within the kiln, expanded clay can have approximately circular or potato-shaped forms and is available in various sizes and densities. Expanded clay has been used to prepare lightweight concrete products (see, for example, website: https: / / www.archiexpo.com / architecture-design-manufacturer / expanded-clay-aggregate-concrete-23000.html) and for other applications. Expanded clay is commonly known by the trademark LECA (an acronym for lightly expanded clay aggregate) or LIAPOR (porous lias clay), and is also called Hydroton. In non-proprietary terms, it refers to spherical pellets of sintered and expanded clay, such as sintered clay pebbles, grown rock, expanded clay, or hydrocorns (see, for example, website: https: / / www.sciencedirect.com / topics / engineering / expanded-clay-aggregate).

[0149] 11. A thermal runaway barrier according to any one of embodiments 1 to 10, 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 or only nominal loose particles. PCW typically contains up to 5% loose particles, while alkaline earth silicate (AES) fibers contain up to 60% particles when uncleaned and contain as little as about 10%-30% minimum loose particles when cleaned.

[0150] 12. The thermal runaway barrier according to any one of embodiments 1 to 11, 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 (3MSCOTCHCAST 265, 3MSCOTCHKOTE 6258)) or liquid binder (e.g., acrylic latex, ethylene vinyl acetate (EAF68) latex, silicone resin, polyurethane, etc.).

[0151] 13. The thermal runaway barrier according to any one of embodiments 1 to 12, wherein the nonwoven fiber thermal insulation layer is encapsulated by the organic encapsulation layer.

[0152] 14. The thermal runaway barrier according to embodiment 13, wherein the organic encapsulation layer has at least one vent formed through the organic encapsulation layer, the at least one vent being positioned and sized to allow expanding gas (e.g., air) contained within the thermal runaway barrier to escape from the organic encapsulation, such that the structural integrity of the organic encapsulation layer is maintained (i.e., the nonwoven fiber thermal insulation layer remains fully, mostly, or at least significantly encapsulated by the organic encapsulation layer) when the thermal runaway barrier is compressed during the 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 overheating of adjacent battery cells). Each vent may be rectangular in shape (see, for example, Figure 8 ( ), circular shape, oval shape, or any other desired shape or 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 (see, for example, Figure 8 The left vent 54 and Figure 7 Vent holes 54 in the encapsulation. Optionally, one or more or each vent hole may be formed inside the side edge of the encapsulation and adjacent to the nonwoven thermal insulation (see [link]). Figure 8 Right side vent 52 and Figure 6 Ventilation holes 52). Additionally, one or more or each ventilation hole may be located on only one side of the nonwoven fiber thermal insulation (see [reference]). Figure 6 Vent 52 on the right side or on both sides (see vent 52 on the right side) Figure 6 The vent 52 on the upper left side is formed by an encapsulation layer. It may also be necessary for each vent to be in the form of multiple small perforations, which are aggregated together (e.g., like a screen, sieve, or filter) to provide the desired outlet opening area.

[0153] 15. The thermal runaway barrier according to embodiment 13 or 14, wherein the thermal runaway barrier has a top edge, a bottom edge and opposing side edges, and the at least one vent is positioned along the periphery of one or both opposing side edges.

[0154] 16. The thermal runaway barrier according to any one of embodiments 13 to 15, wherein the at least one vent provides an outlet opening through the organic encapsulation layer, the outlet opening having a diameter of about 2 mm. 2 Up to about 15mm 2 The opening area within the range. It is conceivable that it may be necessary to have any specific area within this range, or any narrower range within this range.

[0155] 17. A thermal runaway barrier according to any one of embodiments 13 to 16, wherein the organic encapsulation layer is in the form of a continuous layer, a discontinuous layer (e.g., having perforations, through-holes, or pores that allow gas to permeate the organic layer), or a combination of both. Additionally, the organic layer may be in the form of an organic (e.g., polymer) film, a loosely woven fabric, a woven or nonwoven fabric, an adhesive (e.g., a thermoplastic or hot-melt adhesive) layer, or a combination thereof. One embodiment of the organic layer is a polymer film (e.g., a copolyester polymer film).

[0156] 18. The thermal runaway barrier according to any one of embodiments 13 to 17, wherein the organic encapsulation layer is a calendered layer, a hot-melt coated layer, a spray-coated layer, an dip-coated layer, or a laminate (e.g., wherein pressure-sensitive adhesives or other adhesives are used).

[0157] 19. The thermal runaway barrier according to any one of embodiments 13 to 18, wherein the nonwoven fiber thermal insulation layer has a peripheral edge, and the organic encapsulation layer is sealed around the peripheral edge.

[0158] 20. The thermal runaway barrier according to any one of embodiments 1 to 19, wherein the nonwoven fiber thermal insulation layer passes at least the V-2 or V-1 rating of the UL94 flammability test, and preferably the V-0 rating.

[0159] Flammability test

[0160] This test was performed using the UL-94 standard (a standard for testing the safety of flammability of plastic materials in parts of equipment and appliances). The UL-94 standard is a flammability standard for plastics published by Underwriters Laboratories. This standard determines the tendency of a material, after being ignited, to either extinguish itself or spread the flame. The UL-94 standard is harmonized with IEC 60707, 60695-11-10, and 60695-11-20, and ISO 9772 and 9773. A 75mm × 150mm sample was exposed to a 2cm, 50W tirrel burner flame ignition source. The test sample was placed vertically above the flame, and the flame impact on the bottom of the sample was tested. For each sample, the extinguishing time was measured and a V-rating was assigned. The V-rating is a measure of the extinguishing time without the sample burning to the top clamp or dripping molten material capable of igniting a cotton swab indicator, as shown in Table 1 below.

[0161] Table 1. UL94 Classification (Level V).

[0162]

[0163] 21. The thermal runaway barrier according to any one of embodiments 1 to 20, wherein the thermally insulating inorganic particles are prepared from or at least comprise particles of an irreversibly or permanently expanding expandable material (e.g., an expandable material).

[0164] 22. The thermal runaway barrier according to embodiment 21, wherein the thermally insulating inorganic particles are prepared from or at least comprise particles of an expanded expandable material, the particles of which have been irreversibly or permanently expanded to at least about 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80% or 90% to at most 100% of their expandability.

[0165] 23. The thermal runaway barrier according to any one of embodiments 1 to 20, wherein the thermally insulating inorganic particles are prepared from or at least comprise irreversibly or permanently expanded particles (e.g., vermiculite particles).

[0166] 24. The thermal runaway barrier according to embodiment 23, wherein the expanding particle (e.g., vermiculite particle) has irreversibly or permanently expanded to at least about 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80% or 90% to at most 100% of its expandability.

[0167] 25. The thermal runaway barrier according to any one of embodiments 1 to 24, wherein the thermally insulating inorganic particles further include at least fumed silica particles.

[0168] 26. The thermal runaway barrier according to embodiment 25, wherein the surface area of ​​the fumed silica particles is approximately 100 m². 2 / g to at most about 400m 2 Within the range of / g.

[0169] 27. A thermal runaway barrier assembly comprising a plurality of thermal runaway barriers according to any one of embodiments 1 to 26, wherein the plurality of thermal runaway barriers are (a) stacked in a container (e.g., cardboard or other box), (b) connected end-to-end in series, wherein one main surface of each thermal runaway barrier is adhered to the main adhesive surface of a section of double-sided or single-sided tape (when using double-sided tape, the opposing main adhesive surfaces of the tape may be released for padding protection), or (c) connected end-to-end in the form of tape, wherein each thermal runaway barrier is provided end-to-end with a single layer of nonwoven fibrous thermal insulation material and sandwiched or otherwise encapsulated between two opposing lengths of organic (e.g., polymer) encapsulation layers (e.g., in the form of two opposing films, coatings, etc.).

[0170] Battery cell module implementation plan

[0171] 28. A battery cell module or assembly for an electric vehicle, the battery cell module or assembly comprising:

[0172] Multiple battery cells, the multiple battery cells being disposed in a housing; and

[0173] Multiple thermal runaway barriers according to any one of embodiments 1 to 27,

[0174] The battery cells are arranged in rows or stacks, and a thermal runaway barrier is provided between each pair of adjacent battery cells or between a predetermined number of battery cells.

[0175] Method for preparing a thermal runaway barrier for battery cells

[0176] 29. A method for preparing the thermal runaway barrier according to any one of embodiments 1 to 27, wherein the method includes forming the nonwoven fiber thermal insulation layer using a wet web forming process or a dry web forming process.

[0177] 30. The method according to embodiment 29, further comprising:

[0178] Provide thermally insulating inorganic particles that are entirely made of unexpanded expanded particles (e.g., unexpanded vermiculite particles or unexpanded perlite particles), are mostly made of such unexpanded expanded particles, or at least include such unexpanded expanded particles.

[0179] The thermally insulating inorganic particles are arranged to be uniformly or consistently distributed throughout or within the nonwoven fiber thermal insulation layer; and

[0180] Unexpanded expanding particles are heated to a certain temperature and heated for a period of time, causing the unexpanded expanding particles to expand irreversibly or permanently.

[0181] The heating occurs either before or after the thermally insulating inorganic particles are placed within the nonwoven fiber thermal insulation layer.

[0182] 31. The method according to embodiment 30, wherein the heating occurs after the thermally insulating inorganic particles are disposed within the nonwoven fiber thermal insulation layer.

[0183] 32. The method according to embodiment 30 or 31, wherein the heating causes the unexpanded expandable particles to irreversibly or permanently expand to at least about 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80% or 90% to at most 100% of their expandability.

[0184] 33. The method according to any one of embodiments 30 to 32, wherein the unexpanded expanded particles include unexpanded vermiculite particles, unexpanded perlite particles, or both.

[0185] 34. The method according to embodiment 29, further comprising:

[0186] Provides thermally insulating inorganic particles prepared entirely of pre-expanded expanded particles (e.g., expanded vermiculite or expanded perlite), or mostly of such pre-expanded expanded particles, or at least comprising such pre-expanded expanded particles; and

[0187] The thermally insulating inorganic particles are arranged to be uniformly or consistently distributed throughout or within the nonwoven fiber thermal insulation layer.

[0188] The pre-expanded expanded particles are formed by heating unexpanded expanded particles to a temperature and time that causes irreversible or permanent expansion of the unexpanded expanded expanded particles before thermally insulating inorganic particles are placed inside the nonwoven fiber thermal insulation layer.

[0189] 35. The method according to embodiment 34, wherein the pre-expanded expandable particles irreversibly or permanently expand to at least about 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80% or 90% to at most 100% of their expandability.

[0190] 36. The method according to embodiment 34 or 35, wherein the pre-expanded particles include pre-expanded vermiculite particles, pre-expanded perlite particles, or both.

[0191] Various modifications and alterations may be made to this invention without departing from its spirit and scope. For example, microwave heating is believed to be used to irreversibly or permanently expand particles prepared from expandable materials. It is believed that using microwave energy, rather than baking in an oven, results in more uniform expansion of the expandable particles within the fibrous matrix. Therefore, this invention is not limited to the embodiments described above, but is subject to the limitations mentioned in the embodiments described below and any equivalents thereof. This invention may be suitably practiced without any element not specifically described herein. All patents and patent applications cited above, including those in the background section, are incorporated herein by reference in their entirety.

Claims

1. A thermal runaway barrier operably adapted to be disposed between battery cells of a battery assembly and for at least substantially mitigating a thermal runaway event within the battery assembly, the thermal runaway barrier consisting essentially of: a nonwoven fibrous thermal insulation monolayer including a fibrous matrix of inorganic fibers, thermally insulative inorganic particles dispersed within the fibrous matrix, and a binder dispersed within the fibrous matrix to hold the fibrous matrix together; and an organic encapsulation layer encapsulating the nonwoven fibrous thermal insulation monolayer, wherein the inorganic fibers of the fibrous matrix are selected from the group of fibers consisting of refractory ceramic fibers (RCF), polycrystalline wool (PCW) fibers, basalt fibers, and silicate fibers; and wherein the organic encapsulation layer has at least one vent hole formed therethrough that is positioned and sized to allow gas contained within the thermal runaway barrier to escape from the organic encapsulation layer such that the structural integrity of the organic encapsulation layer remains intact during a thermal runaway event.

2. The thermal runaway barrier of claim 1, wherein the nonwoven fibrous thermal insulation monolayer contains an amount of fibrous particulate in the range of 3 to 60 percent by weight of the amount of inorganic fibers in the nonwoven fibrous thermal insulation monolayer.

3. The thermal runaway barrier of claim 1, wherein the nonwoven fibrous thermal insulation monolayer contains an amount of thermally insulative inorganic particles in the range of as little as 10 to as much as 60 percent by weight of the nonwoven fibrous thermal insulation monolayer.

4. The thermal runaway barrier of claim 1, wherein the nonwoven fibrous thermal insulation monolayer contains an amount of organic binder in the range of as little as 2.5 to as much as 10.0 percent by weight of the nonwoven fibrous thermal insulation monolayer.

5. The thermal runaway barrier of claim 1, wherein the nonwoven fibrous thermal insulation monolayer has an installed thickness in the range of 0.5 mm to less than 5.0 mm.

6. The thermal runaway barrier of claim 1, wherein the nonwoven fibrous thermal insulation monolayer has a basis weight ranging from as low as 250 g / m 2 to as much as 1000 g / m 2 .

7. The thermal runaway barrier of claim 1, wherein the uncompressed basis weight of the nonwoven fibrous thermal insulation monolayer is in the range of 250 g / m 2 to 400 g / m 2 .

8. The thermal runaway barrier of claim 1, wherein the thermally insulative inorganic particles comprise particles of one or any combination of materials selected from the group consisting of inorganic aerogels, xerogels, hollow or porous ceramic microspheres, unexpanded vermiculite, irreversibly expanded vermiculite, fumed silica, other forms of porous silica, irreversibly expanded or unexpanded perlite, pumice, irreversibly expanded clays, diatomaceous earth, titanium dioxide, and zirconium oxide.

9. The thermal runaway barrier of 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 positioned along the perimeter of one side edge or both opposite side edges.

10. The thermal runaway barrier of claim 1, wherein the at least one vent hole provides an exit opening through the organic encapsulant layer having an opening area in a range of 2 mm 2 to 15 mm 2 .

11. The thermal runaway barrier of claim 1, wherein the nonwoven fibrous thermal insulation monolayer has a peripheral edge, and the organic encapsulation layer is sealed around the peripheral edge.

12. The thermal runaway barrier of claim 1, wherein the nonwoven fibrous thermal insulation monolayer passes at least a V-2 rating of the UL94 flammability test.

13. The thermal runaway barrier of claim 1, wherein the silicate fiber is an alkaline earth silicate fiber.

14. A battery cell module for an electric vehicle, the 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 arranged in rows, with one thermal runaway barrier disposed between each pair of adjacent battery cells.

Images