Flame-resistant materials for electric vehicle batteries

Abstract

[0003] Fire-resistant coatings and fire-barrier-coated articles are provided, the fire-resistant coatings comprising an inorganic binder and at least one inorganic filler, wherein the inorganic binder is selected from potassium silicate, sodium silicate, or a combination thereof, and the at least one inorganic filler is selected from kaolin clay, talc, mica, mullite, phlogopite, muscovite montmorillonite, smectite, bentonite, illite, chlorite, sepiolite, attapulgite, halloysite, vermiculite, laponite, rectorite, perlite, and a combination thereof. The fire-resistant coatings and fire-barrier-coated articles include a flame-resistant substrate layer having a first major surface and a second major surface, and a fire-resistant coating disposed on the first major surface of the flame-resistant substrate layer.

Description

[Technical Field]

[0001] FIELD OF THE INVENTION The present invention relates to a fire barrier article for managing thermal runaway events in battery modules of electric vehicles, and more particularly, in battery modules. The provided article can be particularly useful in, for example, automotive and stationary energy storage applications. [Background technology]

[0002] Today, the market and supporting technologies for battery-assisted hybrid or fully electric vehicles are expanding rapidly. Rechargeable batteries, including nickel-metal hydride or lithium-ion batteries, are used to store energy and provide power in electric and hybrid electric vehicles. The flow of current either to the battery during recharging or from the battery to the vehicle and its accessories generates heat. Operation outside the specified range boundaries can damage or accelerate the degradation of cells within the battery.

[0003] Electric vehicle batteries are composed of several battery modules, each containing many interconnected individual battery cells. When a cell within a battery module is damaged or defective in its operation, the temperature within the cell can rise faster than heat can be removed from the module. If this temperature rise is allowed to continue, a catastrophic phenomenon called thermal runaway can occur, resulting in the cell ignition. The resulting fire can spread very quickly to adjacent cells in a chain reaction, and then to cells throughout the battery. These fires can potentially become large and spread to surrounding structures, endangering occupants of the vehicle or the structure in which these batteries are located.

[0004] In the event of thermal runaway within a cell, it is desirable for a thermal management system to block or absorb heat and prevent adjacent cells or modules from overheating and entering thermal runaway. The serious risks posed by a thermal runaway event require battery modules to be designed with an insulating fire barrier to mitigate the effects of a thermal runaway event and provide time for occupants to safely exit the vehicle in the event of a fire. Summary of the Invention

[0005] In one aspect of the present invention, there is provided a fire-resistant coating comprising an inorganic binder and at least one inorganic filler, wherein the inorganic binder is selected from potassium silicate, sodium silicate, or a combination thereof, and the at least one inorganic filler is selected from kaolin clay, talc, mica, mullite, phlogopite, muscovite montmorillonite, smectite, bentonite, illite, chlorite, sepiolite, attapulgite, halloysite, vermiculite, laponite, rectorite, perlite, and a combination thereof.

[0006] In another aspect of the present invention, a fire barrier article is provided that includes a flame-resistant substrate layer having a first major surface and a second major surface; and a fire-resistant coating disposed on a substantial portion of the first major surface of the flame-resistant substrate layer, wherein the fire-resistant coating composition includes an inorganic binder and at least one inorganic filler, wherein the inorganic binder is selected from potassium silicate, sodium silicate, or a combination thereof, and the at least one inorganic filler is selected from kaolin clay, talc, mica, mullite, phlogopite, muscovite montmorillonite, smectite, bentonite, illite, chlorite, sepiolite, attapulgite, halloysite, vermiculite, laponite, rectorite, perlite, and a combination thereof. [Brief explanation of the drawings]

[0007] [Figure 1]1 illustrates an exemplary battery module including a thermal barrier formed from an insulating material according to an aspect of the present invention. [Figure 2] 1 illustrates an exemplary battery pack including a thermal barrier formed from an insulating material according to an aspect of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0008] In the following detailed description, reference is made to the accompanying drawings, which form a part hereof, and in which is shown, by way of illustration, specific embodiments in which the present invention may be practiced. In this regard, directional terms, such as "upper," "lower," "front," "rear," and "forward," are used with reference to the orientation of the drawings being described. Because components of each embodiment of the present invention can be positioned in many different orientations, the directional terminology is used for purposes of explanation and not limitation. It is to be understood that other embodiments may utilize structural or logical changes without departing from the scope of the present invention. Therefore, the following detailed description is not to be taken in a limiting sense, and the scope of the present invention is defined by the appended claims.

[0009] Protecting against the dangers associated with sudden fires during thermal runaway events is a significant technical challenge. Attempting to create a universal solution is difficult to achieve because protecting against one characteristic of battery fires can lead to other types of problems. For example, nonwoven polymer webs and foams can exhibit excellent thermal insulation properties, but common polymers are flammable or must be coated with flammable sealing materials. Heat barriers made from non-flammable fibers (e.g., inorganic fibers) can be effective at preventing fire penetration, but may be too thin to adequately insulate against the intense heat of a fire. Using thicker layers of heat barrier material can be cost-prohibitive. While combinations of these materials can work, different materials bonded together can be problematic, especially when the choice of bonding material may be constrained by flammability issues.

[0010] The present invention addresses these problems by providing a fire barrier article that combines a fire-resistant coating that forms a protective ceramic surface under thermal runaway conditions, the fire-resistant coating disposed on a flame-resistant paper or board. In electric vehicle battery applications, the combination of a relatively thin flame-resistant paper or board and a fire-resistant coating can provide protection in the event of fire heating, structural integrity, and a high degree of thermal insulation.

[0011] In one aspect of the present invention, a fire-resistant coating is provided that includes an inorganic binder and at least one inorganic filler.

[0012] In another aspect of the present invention, a fire barrier article is provided that includes a flame-resistant substrate layer having a first major surface and a second major surface, and a fire-resistant coating disposed on a substantial portion of the first major surface of the flame-resistant substrate layer.

[0013] A fire barrier article 100 according to one embodiment is shown in Figure 1. The fire barrier article 100 includes a flame-resistant substrate layer 110 having a first major surface 112 and a second major surface 114, and a fire-resistant coating layer 120 disposed on a substantial portion of the first major surface of the flame-resistant substrate layer. The coating layer can be applied by spraying, painting, etc., at a thickness of 200 microns to 2000 microns, preferably 400 microns to 1000 microns.

[0014] Exemplary flame-resistant substrate layers useful in the present invention can be flame-resistant paper, such as inorganic paper or mica-based paper; inorganic fabric; flame-resistant board, such as inorganic fiberboard or mica board or sheet; or flame-resistant laminate or multilayer material comprising one or more of the foregoing materials. The inorganic fabric can include E-glass fiber, R-glass fiber, ECR-glass fiber, basalt fiber, ceramic fiber, silicate fiber, Nextel fiber, steel filament, or a combination thereof. The fibers in the inorganic fabric can be chemically treated. The textile can be, for example, a woven or nonwoven mat, felt, cloth, knitted fabric, stitch-bonded fabric, crocheted fabric, interlaced fabric, or a combination thereof.

[0015] The multilayer material according to the present invention may also include at least one layer containing inorganic particles or inorganic fibers, or a combination thereof, and at least a second layer containing a flame-resistant foam nonwoven mat or other porous material; a flame-resistant fabric material in the form of a film or nonwoven material, or a flame-resistant polymeric material. The inorganic fibers of the at least one layer containing inorganic particles or inorganic fibers may be selected from the group consisting of E-glass fibers, S-glass fibers, R-glass fibers, ECR-glass fibers, basalt fibers, ceramic fibers, polycrystalline fibers, silicate fibers, alumina fibers, silica fibers, carbon fibers, silicon carbide fibers, boron silicate fibers, or combinations thereof. More specifically, the fibrous material may include annealed melt-formed ceramic fibers, sol-gel-formed ceramic fibers, polycrystalline ceramic fibers, alumina-silica fibers, or glass fibers, including annealed glass fibers or non-bio-persistent fibers. The inorganic fabric can be, for example, a nonwoven mat, a stitch-bonded mat, a needled mat, a chemically bonded mat using either inorganic or polymeric binders (both of which are described in more detail below), or a thermally bonded mat (mono- or bi-component fibers or powders), or a combination thereof. Other fibers are also possible if they can withstand the high temperatures generated in a Li-ion battery thermal event.

[0016] Exemplary polymeric binders that can be used to create chemically bonded mats include (meth)acrylic binders, rubber-based binders, styrene acrylic binders, styrene butadiene binders, urethane acrylate binders, silicone binders, vinyl polymer binders, epoxy binders, etc. In exemplary embodiments, the polymeric binder can be an aqueous polymer dispersion based on acrylate, styrene, urethane monomers, etc., or compositions / copolymers thereof.

[0017] Exemplary flame resistant polymeric materials include acrylamide-based materials, fluoropolymer-based materials, oxidized polyacrylonitrile materials, and the like.

[0018] In some exemplary embodiments, the flame-resistant substrate layer 110 can be an electrically insulating material, such as that described in PCT Publication No. WO 2020 / 023357, which is incorporated herein in its entirety. The flame-resistant substrate layer 110 is thermally and electrically insulating and may be in the form of an inorganic insulating paper or board. Multiple sheets, i.e., plies or sublayers, of inorganic paper layers can be wet-laminate and pressed to provide an inorganic board or multi-layer paper material with thermal and electrical insulating properties. The term "paper" refers to a flexible single or multi-layer material that is flexible enough to be bent around a 3-inch mandrel. The term "board" refers to a relatively stiff material that can be bent but does not have the ability to wrap around a mandrel.

[0019] The flame-resistant substrate layer 110 may include a combination of inorganic fibers and inorganic particles and may be referred to as an inorganic paper or board depending on the thickness and flexibility of the insulating material. The flame-resistant substrate layer 110 is primarily composed of inorganic materials (i.e., inorganic fibers and fillers). In an exemplary embodiment, the flame-resistant substrate layer 110 includes at least 95% inorganic materials. In an exemplary embodiment, the flame-resistant substrate layer 110 includes at least 96% inorganic materials. The highly inorganic nature of the exemplary flame-resistant substrate layer improves the flame resistance of these materials over other conventional insulating papers. In some embodiments, the flame-resistant substrate layer may include small amounts (e.g., less than 5% by weight) of organic fibers or polymer additives.

[0020] The fire-resistant coating layer 120 is formed by applying an exemplary coating composition that is applied by spraying, painting, etc. The exemplary coating composition of the present invention includes an inorganic binder and at least one inorganic filler. The exemplary coating composition can be a solvent-based coating or an aqueous-based coating, preferably an aqueous-based coating composition.

[0021] Exemplary inorganic binders include sodium silicate, potassium silicate, or a combination thereof. In some embodiments, the inorganic binder has the formula MO(SiO)n The inorganic binder may be a polysilicate having a molar ratio of 1:1 or 1:2, preferably 1:1, 1:2, 1:3, 1:4, 1:5, 1:5, 1:6, 1:7, 1:8, 1:9, 1:10, 1:11, 1:12, 1:13, 1:14, 1:15, 1:16, 1:17, 1:18, 1:19, 1:20, 1:21, 1:22, 1:23, 1:24, 1:25, 1:26, 1:27, 1:28, 1:29, 1:30, 1:31, 1:32, 1:33, 1:34, 1:35, 1:40, 1:41, 1:42, 1:43, 1:44, 1:45, 1:46, 1:47, 1:50, 1:51, 1:52, 1:53, 1:54, 1:55, 1:56, 1:57, 1:58, 1:59, 1:60, 1:61, 1:62, 1:63, 1:64, 1:65, 1:70, 1:71, 1:72, 1:73, 1:74, 1:75, 1:76, 1:77, 1:78, 1:79, 1:80, 1:81, 1:82, 1:83, 1:84, 1:85, 1:86, 1:87, 1:88, 1:90, 1:91, 1:92, 1

[0022] The content of the particulate inorganic filler in the coating composition is about 20% to 90% by weight, preferably 40% to 80% by weight, based on the percent solids in the dry coating. Exemplary inorganic fillers include, but are not limited to, kaolin clay, talc, mica, mullite, phlogopite, muscovite montmorillonite, smectite, bentonite, illite, chlorite, sepiolite, attapulgite, halloysite, vermiculite, laponite, rectorite, perlite, glass fiber, ceramic fiber, and combinations thereof. Suitable types of kaolin clay include, but are not limited to, water-washed kaolin clay, metakaolin clay, delaminated kaolin clay, calcined kaolin clay, and surface-treated kaolin clay.

[0023] In some embodiments, a polymeric binder material can be added to the exemplary coating composition. Exemplary polymeric binders include (meth)acrylic binders, rubber-based binders, styrene-acrylic binders, styrene-butadiene binders, urethane acrylate binders, silicone binders, vinyl polymer binders, epoxy binders, etc. In exemplary embodiments, the polymeric binder can be an aqueous polymer dispersion of acrylate, styrene, urethane monomers, etc., or compositions / copolymers thereof.

[0024] In some embodiments, additives may be added to the exemplary coating composition. Exemplary additives include antifoaming agents, surfactants, rheology modifiers, forming aids, pH adjusting materials, etc. Exemplary rheology modifiers may be organic compounds, preferably selected from polysaccharides, proteins, and polyvinyl alcohols, preferably natural and modified polysaccharides, preferably polysaccharides selected from the list consisting of xanthan, carrageenan, pectin, gellan, xanthan gum, diuthan, carboxymethylcellulose, methylcellulose, ethylcellulose, and hydroxyethylcellulose.

[0025] As previously described, the fire-resistant coating composition can be applied to a first major surface of a flame-resistant substrate layer to form an exemplary fire barrier article that can be used as a protective device or system, such as a heat / flame barrier. For example, one or more sheets of the exemplary fire barrier article can be incorporated into or wrapped around a combustible energy storage device, such as a lithium-ion battery cell, module, or pack, such as may be found in a hybrid or electric vehicle or other electric transportation application or location. In other applications, the exemplary fire barrier article can be used as a lid / pack liner for the combustible energy storage device.

[0026] Exemplary fire barrier articles of the present invention should prevent heat from flowing from a failed cell or module to an adjacent cell or module or to the passenger compartment. For example, exemplary fire barrier articles should provide a high thermal gradient or temperature drop across the material when one side of the material is exposed to high temperatures. Alternatively, exemplary fire barrier articles may be used as a thermal barrier wrap or as a thermal barrier lid within a battery pack of an electric vehicle that can prevent or reduce heat flow from the battery pack. [Example]

[0027] These examples are for illustrative purposes only and are not intended to limit the scope of the appended claims. All parts, percentages, ratios, etc. in the examples and elsewhere herein are by weight unless otherwise specified.

[0028] Test Method Sandblasting Test To simulate a thermal runaway event, the samples were preconditioned in an oven at either 25°C, or 1000°C or 1200°C for 10 minutes.

[0029] For sandblasting tests, a commercially available sandblasting cabinet, such as the Professional Sand Blasting Desktop Cabinet from PowerPlusTools GmbH (Germany), is used. The sample material is attached to a metal sheet specimen holder measuring 100 mm x 50 mm. A specimen measuring 80 mm x 50 mm is secured to all sides of the metal sheet with masking tape. A fixture within the cabinet holds the specimen in a defined position in front of the nozzle. Compressed air is used to accelerate sandblasting media (type 211 glass beads, particle size 70-110 μm) against the specimen surface until the specimen (i.e., the specimen) is damaged over an area 4 + / - 1 mm in diameter, and the elapsed time of the test is recorded. Additionally, a normalized abrasion resistance value is calculated by normalizing the elapsed exposure time by the specimen thickness / caliper. Exemplary results can be found in Tables 3-5.

[0030] Blast resistance test: The resistance of the specimens to thermal particle blast was tested to simulate electric vehicle high energy batteries in thermal runaway conditions, which not only burn but also blast particles that can erode materials at high combustion temperatures.

[0031] After equilibrating the test pieces with a flame at 1200 °C, the samples were subjected to a series of grit blasts lasting 10 seconds, followed by a 5 - second pause period. The grit was blasted onto the substrate with a 25 psi compressed air pressure source, and the grit particles were a 120 - grit aluminum oxide non - formed medium. These 10 - second blasts and 5 - second pauses (the flame was continuously applied) were repeated until the flame and grit penetrated through the test pieces. The coated side of the test piece sheet structure was oriented towards the hot particle blast. The number of blasts remaining before the entire structure was penetrated was recorded and shown in Table 7.

[0032] Peel Test To measure the adhesion of the coating to the substrate, a peel adhesion test was performed.

[0033] 3M #1205 polyimide tape (25.4 - micron polyimide backing with a 25.4 - micron acrylate pressure - sensitive adhesive) available from 3M Company (St. Paul, MN USA) was adhered to each substrate / test piece and aged at 65 °C for 20 minutes to cure the adhesive. Then, the tape was peeled from the various substrates at 30.5 cm / min in a 180 - degree peel mode. The peel test results are shown in Table 7.

[0034] Materials Materials for the inorganic coating composition KASIL® 2130 potassium silicate solution (MR > 3.2; 30% solids) available from National Silicates (Germany).

[0035] KASIL® 1 potassium silicate solution (MR > 3.2; 29% solids) available from PQ Corporation (Valley Forge, PA USA).

[0036] KASIL® 6 potassium silicate solution (2.6 < MR ≤ 3.2; 39% solids) available from PQ Corporation (Valley Forge, PA USA).

[0037] A K® sodium silicate solution (2.6 < MR ≦ 3.2; 43% solids) available from PQ Corporation (Valley Forge, PA USA).

[0038] An ultra-high purity sodium silicate solution available from Merck KGaA (Germany).

[0039] An ACRONAL® S980S acrylic polymer dispersion (45% solids) available from BASF (Germany).

[0040] KELTROL® BT xanthan gum available from CP Kelco (Atlanta, GA, USA).

[0041] Poly(vinyl alcohol), 95% hydrolyzed, average molecular weight 95000, also available from Fisher Scientific AG (Switzerland).

[0042] CELLOSIZE® QP 100MH hydroxyethyl cellulose available from Dow Chemical Company (Midland, MI, USA).

[0043] METAPOR® MVV metakaolin available from Dennert Poraver GmbH (Germany).

[0044] SYMULOX® M72 synthetic sintered mullite available from Nabaltec (Germany).

[0045] Phlogopite available from Georg.H.Luh GmbH (Germany).

[0046] Suzorite 200-HK phlogopite (median particle size of 1300 microns) available from Imerys (Boucherville, Quebec, CA).

[0047] Suzorite 20S phlogopite (60 micron median particle size) available from Imerys (Boucherville, Quebec, CA).

[0048] Aspaga mica available from Aspager Bergbau und Mineralwerke GmbH&Co KG (Germany).

[0049] Polyplate® P water-washed kaolin clay available from Kamin LLC (Macon, GA, USA).

[0050] Unifrax E glass microfiber (6 micron diameter, 6 mm length) available from Unifrax (Tonawanda, NY USA).

[0051] 3M™ Nextel™ Chopped Fiber 720 Nextel Fiber available from 3M Company (St. Paul, MN USA).

[0052] Materials for flame-resistant paper (FRP) EC6-6E glass chopped strand fiber (6 mm length, 6 μm diameter) available from Lauscha Fiber International Corporation (Charlotte, NC, USA).

[0053] B-06-F microglass fiber (0.65 μm diameter, 2.47 m surface area) available from Lauscha Fiber International Corporation (Charlotte, NC, USA) 2 / g).

[0054] M aramid fiber (2 denier, 6 mm length) available from Aramid HPM, LLC (Hilton Head, SC, USA).

[0055] Suzorite 200-HK phlogopite available from Imerys (Boucherville, Quebec, CA).

[0056] Hydraprint, a delaminated kaolin clay available from Kamin LLC (Macon, GA, USA).

[0057] Kamin 70C, a calcined kaolin clay available from Kamin LLC (Macon, GA, USA).

[0058] N-sodium silicate available from PQ Corporation (Valley Forge, PA, USA).

[0059] Mica base material 386g / m available from GloryMica (Zhejiang, China) 2 GloryMica rigid phlogopite sheet (R-5660-H3) of 0.2 mm having a measured basis weight of

[0060] 975g / m available from GloryMica (Zhejiang, China) 2 GloryMica rigid phlogopite sheet (R-5660-H3) of 0.5 mm having a measured basis weight of

[0061] 1736 g / m available from GloryMica (Zhejiang, China) 2 GloryMica rigid phlogopite sheet (R-5660-H3) of 0.8 mm having a measured basis weight of

[0062] 1984 g / m available from GloryMica (Zhejiang, China) 2 1.0 mm GloryMica rigid phlogopite sheet (R-5660-H3) with a measured basis weight of

[0063] Coating Composition The binder material was placed in a mixing vessel. The inorganic particles were crushed and sieved to produce particles with an average particle size of 10 microns. The sieved particles were added to the binder solution to obtain a uniform coating.

[0064] For the coatings of Examples Ex.1-Ex.4, compositional information is provided in Table 1, and test data is provided in Tables 3 and 4. For Examples Ex.8-Ex.12, compositional information is provided in Table 2, and test data is provided in Table 5.

[0065] Examples Ex.5 to Ex.7 Examples Ex.5 to Ex.7 were modified to include a rheology modifier: The binder was placed in a mixing vessel, the rheology modifier was added, and the mixture was stirred until the rheology modifier was dissolved.

[0066] The inorganic particles were crushed and sieved to produce particles with an average particle size of 10 microns. The sieved particles were added to a binder solution to obtain a homogeneous coating. Composition information for the coatings of Examples Ex. 5 to Ex. 7 is provided in Table 1. [Table 1] [Table 2]

[0067] The exemplary coating composition was coated onto the flame-resistant paper (FRP) or board (FRB) described below, or onto a three-dimensional flame-resistant barrier as described below. The flame-resistant board (FRB) used is the flame-resistant board described in Example 8-B of PCT Publication No. WO2020 / 023357.

[0068] Uncoated flame resistant paper FRB or board was used as a control sample. Test results for the exemplary compositions of Tables 1 and 2 are provided in Tables 3-5.

[0069] Flame-resistant paper (FRP) and three-dimensional flame-resistant paper products The composite consisted of 3.5 wt% EC6-6 E-glass fiber (length 6 mm, diameter 6 μm), 3.9 wt% m-aramid fiber, and 1.6 wt% B-06-F microglass fiber (diameter 0.65 μm, length 2.47 m). 2 28.0 wt.% 200-HK phlogopite, and 21.0 wt.% calcined kaolin clay, Kamin 70C, were pre-dispersed in water in a Waring blender to form an aqueous slurry with approximately 0.05-1 wt.% solids, which was then mixed into a larger container containing 33.0 wt.% delaminated kaolin clay, Hydraprint, and 9.0 wt.% N-sodium silicate. Additional materials known to those skilled in the art, such as antifoaming agents, surfactants, forming aids, and pH adjusters, can also be incorporated. Dewatering is carried out through a papermaking screen and press (Williams Standard Pulp Testing Apparatus) to form a precursor sheet of flame-resistant paper material, which can be dried to form flat sheets of flame-resistant paper or board.

[0070] Alternatively, a precursor sheet of the flame-resistant paper material can be applied to a three-dimensional surface and dried on a mold to create a three-dimensional shaped flame-resistant article. Exemplary three-dimensional shaped flame-resistant barriers are described in commonly assigned U.S. Provisional Application No. 62 / 942,284, "Flame Resistant Materials for Electric Vehicle Battery Applications," filed December 2, 2019, which is incorporated herein by reference in its entirety. [Table 3] [Table 4]

[0071] In Examples Ex. 1-4, the coating compositions transformed into ceramic-like layers when subjected to high temperature preconditioning at 1200° C., which generally provided improved wear resistance to the coated article. [Table 5]

[0072] The inorganic additive phlogopite with metakaolin stabilized the TFRB plate, resulting in higher grinding stability. Interestingly, the coatings containing sodium silicate (Examples 10-12) appear to begin stabilizing the TFRB at 1000°C, while the coatings with potassium silicate (Examples 1, 8, and 9) appear to begin stabilizing the TFRB at approximately 1200°C.

[0073] FIG. 2 shows an exemplary three-dimensional fire barrier article in which a three-dimensional molded flame resistant paper article is coated with Coating Composition Example 3.

[0074] Examples Ex.13 to Ex.18 For each coating composition, all solid materials were added to a mixing vessel and mixed by hand. The liquid binder was then added and mixed by hand until the solids in the resulting slurry or paste were fully wetted. The mixture was then mixed in a FlackTek SpeedMixer at 3,000 rpm for 2 minutes. The compositions were then coated onto mica sheets of either 0.2 or 0.5 mm thickness and allowed to dry overnight at ambient conditions. The final drying conditions were initially 80°C for 40 minutes, then the temperature was increased to 120°C for 60 minutes. Examples Ex. 13 to Ex. 17 were coated at 1350 g / m². 2 The coating weight (dry basis weight) of the coating was 1736 g / m on a 0.2 mm mica sheet substrate. 2 Example Ex. 18 included exemplary coatings that resulted in coated structures with an overall basis weight of 1010 g / m (equivalent to the basis weight of a 0.8 mm mica sheet). 2 The coating weight (dry basis weight) of the coating was 1984 g / m on a 0.5 mm mica sheet substrate. 2 Another exemplary coating composition was included that resulted in a coated structure having an overall basis weight of 1.0 m (equivalent to the basis weight of a 1.0 m mica sheet). The coatings used on the coated structures of Examples Ex. 13-18 are provided in Table 6. [Table 6] [Table 7]

[0075] As shown in Table 7, because the individual mica flakes in the mica sheet are not strongly bonded to one another, the acrylate adhesive had very low peel values ​​for removal from the mica sheet due to the peeling of the surface mica flakes (Comparative Example C2). The tape adhesive peeled off a thin layer of mica flakes, effectively removing the adhesive and demonstrating the difficulty of adhering to the surface of the mica sheet. In contrast, each of the exemplary coating compositions of Examples Ex. 13-18 produced much higher peel values. The peel values ​​of the acrylate adhesive from the coating of the present invention ranged from 13 to 17 times that of the acrylate adhesive adhered to the surface of the mica sheet.

[0076] Table 7 also shows how the exemplary coated mica sheets and corresponding uncoated mica sheets with the same basis weight as the coated mica sheets performed in terms of blast resistance. Comparative Example C3 survived six blasts (average of two separate tests), while Examples 13-15, with the same total basis weight as Comparative Example C3, survived approximately twice as many thermal particle blasts. Example 16 survived one more thermal particle blast than Comparative Example C3, demonstrating that it also provides superior blast protection than the mica sheet alone. Similarly, Example 18 survived longer than the corresponding uncoated mica sheet (Comparative Example C4). Example 18 survived 16 thermal particle blasts without punctures. Although no structure was lost, the test was discontinued. This also demonstrates the ability of this coating on mica sheets to provide excellent blast resistance while also having excellent adhesion to pressure-sensitive adhesives.

[0077] Examples Ex. 13-18 illustrate the benefits of coating mica substrates with the exemplary coating compositions described herein. Generally, mica materials are known to have excellent dielectric strength in the range of 15-30 kV / mm. The exemplary inorganic coatings shown in Table 6, when fully dried, have a dielectric strength of approximately 5-10 kV / mm. Thus, mica sheets coated with the exemplary inorganic coatings can provide the excellent balance of adhesion, blast resistance, and dielectric strength required for protection in high-energy battery applications.

[0078] In light of this specification, various modifications of the exemplary electrically insulating materials described herein, including equivalent processes, as well as numerous structures to which the present invention may be applicable, will be readily apparent to those skilled in the art to which the present invention is directed. In addition to the embodiments, the following aspects will be noted. (Appendix 1) an inorganic binder; at least one inorganic filler; the inorganic binder is selected from potassium silicate, sodium silicate, or a combination thereof; the at least one inorganic filler is selected from kaolin clay, talc, mica, mullite, phlogopite, muscovite, montmorillonite, smectite, bentonite, illite, chlorite, sepiolite, attapulgite, halloysite, vermiculite, laponite, rectorite, perlite, glass fiber, ceramic fiber, and combinations thereof; Fire-resistant coating composition. (Appendix 2) 2. The coating composition of claim 1, wherein the kaolin clay is water-washed kaolin clay, metakaolin clay, delaminated kaolin clay, calcined kaolin clay, or surface-treated kaolin clay. (Appendix 3) 3. The coating composition of claim 1 or 2, further comprising a polymeric binder. (Appendix 4) 4. The coating composition of claim 3, wherein the polymer binder is a (meth)acrylic binder, a rubber-based binder, a styrene-acrylic binder, or a styrene-butadiene binder. (Appendix 5) 5. The coating composition of claim 4, comprising 10% to 80% by weight of a polymeric binder. (Appendix 6) 6. The coating composition according to any one of claims 1 to 5, further comprising a rheology control agent. (Appendix 7) 7. The coating composition of any one of claims 1 to 6, comprising 10% to 80% by weight of an inorganic binder, based on the percent solids in the dry coating. (Appendix 8) 8. The coating composition of any one of claims 1 to 7, comprising 20% ​​to 90% by weight of inorganic filler, based on percent solids in the dry coating. (Appendix 9) 9. The coating composition of any one of claims 1 to 8, which, after drying, transforms into a ceramic-like material upon exposure to high temperatures (>1000°C). (Appendix 10) The coating composition according to any one of claims 1 to 9, which is water-based. (Appendix 11) a flame resistant substrate layer having a first major surface and a second major surface; a fire-resistant coating formed by applying the coating composition of any one of claims 1 to 10 to a substantial portion of the first major surface of the flame-resistant substrate layer; and Fire barrier articles, including: (Appendix 12) 12. The fire barrier article of claim 11, wherein the flame-resistant substrate layer is selected from a flame-resistant paper, a flame-resistant fabric, a nonwoven flame-resistant mat, a flame-resistant film, a flame-resistant board or laminate, or a flame-resistant multilayer material. (Appendix 13) 12. The fire barrier article of claim 11, wherein the flame resistant fabric is one of a woven or nonwoven glass fabric, a basalt fiber fabric, a ceramic fiber fabric, or a silicate fiber fabric. (Appendix 14) 13. The fire barrier article of claim 12, wherein the flame-resistant substrate layer is a two-dimensional sheet of flame-resistant paper. (Appendix 15) 13. The fire barrier article of claim 12, wherein the flame-resistant substrate layer is a two-dimensional flame-resistant board. (Appendix 16) 13. The fire barrier article of claim 12, wherein the flame-resistant substrate layer is a nonwoven flame-resistant mat comprising ceramic or silicate fibers. (Appendix 17) 13. The fire barrier article of claim 12, wherein the flame resistant substrate layer comprises a mica plate or sheet material. (Appendix 18) a plurality of battery cells separated from one another by gaps; a fire barrier article according to any one of claims 11 to 17, disposed in the gap between the battery cells; a battery module including: (Appendix 19) a compartment lid having an inner major surface and an outer major surface, the inner major surface covering the plurality of battery cells; a fire barrier article according to any one of claims 11 to 17 disposed on the interior surface of the compartment lid; a battery module including:

Claims

1. an inorganic binder which is potassium silicate; an inorganic filler which is phlogopite having a median particle size of 60 microns; an inorganic filler which is kaolin clay; 1. A fire-resistant coating composition comprising:

2. The fire-resistant coating composition of claim 1 , further comprising a polymeric binder, a rheology modifier, or a combination thereof.

3. 3. The fire-resistant coating composition of claim 2, wherein the polymeric binder is a (meth)acrylic binder, a rubber-based binder, a styrene-acrylic binder, or a styrene-butadiene binder.

4. The fire-resistant coating composition of claim 3, wherein the polymeric binder is present in an amount of 10% to 31.2% by weight, based on the percent solids of the fire-resistant coating composition.

5. The fire-resistant coating composition of any one of claims 1 to 4, wherein the inorganic binder is present in an amount of 10% to 80% by weight, based on the percent solids of the fire-resistant coating composition.

6. The fire-resistant coating composition of any one of claims 1 to 5, wherein the inorganic filler is present in an amount of 20% to 90% by weight, based on the percent solids of the fire-resistant coating composition.

7. a flame resistant substrate layer having a first major surface and a second major surface; a fire-resistant coating composition comprising an inorganic binder and at least one inorganic filler; Including, the fire-resistant coating composition is disposed on a substantial portion of the first major surface of the flame-resistant substrate layer; the flame-resistant substrate layer includes a mica plate or a mica sheet; the inorganic binder is selected from potassium silicate, sodium silicate, and combinations thereof; 1. A fire barrier article, wherein the at least one inorganic filler is selected from kaolin clay, talc, mica, mullite, phlogopite, muscovite, montmorillonite, smectite, bentonite, illite, chlorite, sepiolite, attapulgite, halloysite, vermiculite, laponite, rectorite, perlite, glass fiber, ceramic fiber, and combinations thereof.

8. 8. The fire barrier article of claim 7, wherein the blast resistance is at least 11 according to a blast resistance test in which the test specimen is equilibrated in a 1200°C flame, and then the test specimen is subjected to repeated 10-second blasts followed by 5-second rest periods with a 120-grit aluminum oxide non-shaped media grid at 25 psi compressed air pressure while the flame is continuously applied, and the number of blasts that the test specimen can withstand before the flame and grit penetrate the test specimen is recorded.

9. 9. The fire barrier article of claim 7 or 8, wherein the flame resistant substrate layer further comprises a material selected from a flame resistant paper, a flame resistant fabric, a nonwoven flame resistant mat, a flame resistant film, a flame resistant board or laminate, or a flame resistant multilayer material.

10. The flame-resistant substrate layer is a flame resistant fabric selected from woven or nonwoven glass fabric, basalt fiber fabric, ceramic fiber fabric, and silicate fiber fabric; a nonwoven flame-retardant mat containing ceramic fibers or silicate fibers; The fire barrier article of any one of claims 7 to 9, further comprising a material selected from:

11. 9. The fire barrier article of claim 7 or 8, wherein the flame resistant substrate layer is a phlogopite sheet.

12. the flame-resistant substrate layer is a phlogopite sheet, the inorganic binder is potassium silicate, the first inorganic filler is phlogopite having a median particle size of 60 microns; the second inorganic filler is kaolin clay; the third inorganic filler is glass fiber; based on the weight of the fire-resistant coating composition, the potassium silicate is present in an amount of 54 wt %; the first inorganic filler is present in an amount of 0.09 wt %; the second inorganic filler is present in an amount of 36 wt %; 9. The fire barrier article of claim 7 or 8, wherein the third inorganic filler is present in an amount of 0.01 wt%.

13. a plurality of battery cells separated from one another by gaps; The fire barrier article of any one of claims 7 to 12 disposed in the gap between the battery cells; a battery module including:

14. a compartment lid having an inner major surface and an outer major surface, the inner major surface covering the plurality of battery cells; a fire barrier article according to any one of claims 7 to 12 disposed on the interior surface of the compartment lid; a battery module including:

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