Inorganic coating composition

Abstract

A coating composition is described that is capable of withstanding high temperature particle impingement without perforation caused by high energy thermal runaway events when the coating composition is applied to a substrate. The coating composition comprises an inorganic filler, an inorganic binder; and a short organic fiber.

Description

Background of the Invention Technical Field

[0002] This invention relates to coating compositions for use in electric vehicle battery modules to help manage thermal runaway events in the battery modules. Background Technology

[0004] Today, the market and supporting technologies for battery-powered hybrid or fully electric vehicles are rapidly expanding. 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 current flowing into or out of the battery during recharging generates heat. Operations outside the specified limits can damage the cells within the battery or accelerate cell degradation.

[0005] Electric vehicle batteries consist of several battery modules, and each module contains many interconnected individual battery cells. When one cell in a battery module fails or malfunctions during operation, the temperature within that cell can rise faster than the heat can be removed from the module. If this temperature buildup continues unchecked, a catastrophic phenomenon known as thermal runaway can occur, causing the cell to catch fire. The resulting fire can spread very rapidly to neighboring cells and then, in a chain reaction, throughout the battery. These fires can be potentially massive and can spread to the vehicle's surrounding structures, endangering occupants or the structures containing these batteries.

[0006] Next-generation electric vehicle (EV) batteries will have significantly higher energy density than those currently used. High-energy batteries, such as those described as 811 (NMC or nickel-manganese-cobalt ratio) or similar, can suffer catastrophic failure if perforated or overheated. When this occurs, the ensuing battery fire will not only reach temperatures of 1200°C or higher but may also eject debris at moderate speeds. While battery packs are typically encased in aluminum cases, aluminum melts at 660°C, so the cases must be protected from the flames and debris of a failed battery to allow EV occupants to evacuate promptly in the event of such a failure.

[0007] While materials capable of withstanding high-temperature flames (i.e., surviving 2000°C flames for tens of minutes without cracking) exist, these materials cannot withstand the explosions associated with thermal runaway events in high-energy batteries. Therefore, a fire barrier is needed that can withstand not only high temperatures but also explosive particles emitted from the battery pack. To survive in automotive or other environments exposed to these elements, these materials must also be able to withstand low and high temperatures and humidity without degrading their performance. Furthermore, exemplary materials need to be thin, lightweight, strong, and inexpensive. Summary of the Invention

[0008] This invention describes a coating that, when applied to a substrate, can withstand high-temperature (e.g., greater than 750°C, preferably greater than 1000°C, or more preferably greater than 1200°C) particle blasting without perforation caused by high-energy thermal runaway events. In a first exemplary embodiment, a coating composition is described comprising inorganic fillers, inorganic binders, and chopped organic fibers.

[0009] In a second embodiment, a refractory article is described, comprising an exemplary coating composition applied to a substrate, wherein the coating composition comprises inorganic fillers, inorganic binders, and chopped organic fibers.

[0010] In another embodiment, the exemplary coating composition according to the invention may substantially consist of: inorganic fillers, inorganic binders, and chopped organic fibers. The coating composition may further include additional materials that do not significantly affect the desired properties of the cured coating composition or the performance of refractory articles comprising the exemplary coating disposed on the surface of a product substrate.

[0011] The above description of the invention is not intended to depict every exemplary embodiment or every implementation of the invention. These embodiments are illustrated more specifically by way of the accompanying drawings and the following detailed description. Detailed Implementation

[0012] Because components of embodiments of the present invention can be positioned in multiple different orientations, directional terminology is used for illustrative purposes and is by no means limiting. It should be understood that other embodiments can be utilized, and structural or logical changes can be made, without departing from the scope of the invention. Therefore, the following detailed description should not be considered limiting, and the scope of the invention is defined by the appended claims.

[0013] Preventing the hazards associated with sudden fires and / or debris ejection during thermal runaway events is a significant technical challenge. Attempting to create a universal solution is difficult because protecting against one characteristic of battery fires can lead to other problems. For example, nonwoven polymer webs and foams exhibit excellent thermal insulation properties, but common polymers cannot withstand the high temperatures experienced during battery failure events. Thermal shielding materials made of woven non-flammable fibers (e.g., inorganic fibers) are effective at preventing fire penetration, but may be too thin to adequately insulate against the immense heat of a fire or debris. Using thicker layers of thermal shielding material can be too costly. Combinations of these materials can provide a solution, but bonding different materials together can be problematic, especially when the choice of bonding materials and adhesives may be limited by flammability issues and differences in coefficients of thermal expansion.

[0014] This invention addresses these problems by providing a fire-retardant coating that forms a protective ceramic surface under thermal runaway conditions. Exemplary coatings can be applied to the surface of fire-retardant paper or fire-retardant boards to form fire-retardant articles capable of withstanding high temperatures and debris ejection during thermal runaway in high-energy battery modules or battery packs. In electric vehicle battery applications, combining relatively thin flame-retardant paper or boards with fire-retardant coatings can provide protection, structural integrity, and high thermal insulation in the event of fire exposure.

[0015] In one exemplary embodiment, a flame-retardant article may be arranged on the underside of a battery pack cover to act as a shield against the explosion or ejection of high-temperature particles during a catastrophic battery failure. This material may be provided to the customer as a separate sheet (for planar applications) or may be coated and cured onto the underside of a battery pack cover (for a battery pack cover with a three-dimensional profile) or other three-dimensional substrate, such as the three-dimensional fire-resistant material described in PCT Publication No. WO 2021 / 113278, which is incorporated herein by reference, and then applied to the cover, sides, or bottom of the battery pack. The requirements for such an exemplary flame-retardant article go far beyond simply being a flame retardant. The flame-retardant article must not only withstand extremely high temperatures but also resist particle explosions. Therefore, conventional constructions containing organic or silicone materials will not provide the necessary protection during high-energy thermal runaway events.

[0016] Furthermore, because automobiles are exposed to a range of shocks and vibrations, extreme temperatures and humidity, chemical exposures, and other adverse conditions, the performance of automotive components must be carefully tuned. Shocks and vibrations can be particularly challenging for many components, as they are subjected to a range of frequencies, accelerations, and bumpy motions, especially when they are firmly attached to the vehicle without any mechanical damping. Therefore, the mechanical properties of materials are an important consideration when formulating new materials for underbody applications.

[0017] For the substantially inorganic coating systems described herein, the materials are characterized using measurements of their flexural properties rather than their tensile properties. Generally, a high flexural modulus and high flexural stress at break are desirable to enable components to withstand the shocks and vibrations of the automotive environment, particularly for underbody applications. Therefore, it is desirable to increase the flexural modulus and / or flexural stress at break of these systems. Based on the percentage of solids in the dried coating, the inorganic coating composition according to the invention comprises at least 90% by weight, preferably at least 93% by weight, and more preferably 97% by weight of inorganic material.

[0018] The exemplary coating composition described herein contains a low concentration of organic fibers to improve the physical properties of the cured composition, while also providing a cured coating capable of withstanding high-temperature particle explosions. This exemplary coating composition can be used on the underside of battery pack covers, or in other applications requiring high temperatures, high strength, and explosion resistance.

[0019] Exemplary coating compositions comprise inorganic fillers, inorganic binders, and chopped organic fibers. More specifically, based on the percentage of solids in the dried coating, the coating composition may comprise 35% to 85% by weight of inorganic fillers, 15% to 60% by weight of inorganic binders, and 0.1% to 6.5% by weight of chopped organic fibers.

[0020] Exemplary inorganic fillers include, but are not limited to, kaolin, metakaolin, talc, mica, mullite, phlogopite, muscovite, montmorillonite, montmorillonite, bentonite, illite, chlorite, sepiolite, palygorskite, halloysite, vermiculite, synthetic lithium saponite, palygorskite, perlite, glass fiber, ceramic fiber, fly ash, pyrolytic silica, Portland cement, concrete mixtures, or similar inorganic materials, and combinations thereof. Suitable types of kaolin include, but are not limited to, washed kaolin, metakaolin, layered kaolin, calcined kaolin, and surface-treated kaolin.

[0021] In some embodiments, the inorganic filler may be a mixture of the various fillers provided above. For example, the inorganic filler may be a mixture of at least two fillers selected from kaolin, metakaolin, talc, mica, mullite, phlogopite, muscovite, montmorillonite, montmorillonite, bentonite, illite, chlorite, sepiolite, palygorskite, halloysite, vermiculite, synthetic lithium saponite, palygorskite, perlite, fly ash, pyrolytic silica, silica fume, Portland cement, and concrete mixtures. In some exemplary embodiments, the inorganic filler is a mixture of kaolin and mica.

[0022] Inorganic fillers may comprise 20% to 70% by weight of the wet coating composition mixture. Alternatively, based on the total solids content in the dried coating, exemplary coating compositions may contain 35% to 85% by weight, preferably 50% to 80% by weight, and more preferably 55% to 75% by weight of inorganic fillers.

[0023] In some embodiments, the inorganic binder may have the formula M₂SiO₃, where M is Na, K, or Li, and therefore includes sodium silicate (Na₂SiO₃), potassium silicate (K₂SiO₃), and lithium silicate (Li₂SiO₃). Additionally, the inorganic binder may also include colloidal silica. In some embodiments, the inorganic binder may comprise a combination of at least two of the inorganic binders provided above (i.e., sodium silicate, potassium silicate, lithium silicate, and colloidal silica). Alternatively, the inorganic binder may have the formula M₂O(SiO₂). n The coating composition is a polysilicate of H2O, wherein M is selected from Li, Na, K, preferably K or Na, and n is an integer between 1 and 15, preferably between 2 and 9. It is also preferred that the binder is used in a solvent (preferably water). The inorganic binder may comprise 30% to 80% by weight of the wet mixture of the coating composition. Alternatively, based on the total solids content in the dried coating, an exemplary coating composition may contain 15% to 60% by weight of inorganic binder, preferably 20% to 50% by weight, more preferably 25% to 45% by weight of inorganic binder.

[0024] Exemplary organic fibers include polyvinyl alcohol (PVA) fibers, polypropylene (PP) fibers, blended polyolefin fibers, polyolefin copolymer fibers, nylon fibers, or combinations thereof. The organic fibers may comprise 0.06% to 5% by weight of the wet coating composition mixture. Alternatively, based on the total solids content in the dried coating, the exemplary coating composition may contain 0.1% to 6.5% by weight of organic fibers, preferably 0.3% to 3% by weight, and more preferably 0.9% to 1.5% by weight of organic fibers.

[0025] In some embodiments, based on the total solids content in the dried coating, the exemplary coating composition may comprise 35% to 85% by weight of inorganic filler, 15% to 60% by weight of inorganic binder, and 0.1% to 6.5% by weight of organic fibers. In other embodiments, based on the total solids content in the dried coating, the exemplary coating composition may comprise 50% to 80% by weight of inorganic filler, 20% to 50% by weight of inorganic binder, and 0.3% to 3% by weight of organic fibers. In other embodiments, based on the total solids content in the dried coating, the exemplary coating composition may comprise 55% to 75% by weight of inorganic filler, 25% to 45% by weight of inorganic binder, and 0.9% to 1.5% by weight of organic fibers.

[0026] As previously mentioned, exemplary coating compositions can be applied to a first primary surface of a substrate to form exemplary fire-retardant articles, which can be used as protective devices or systems, such as thermal / flame barriers. In one exemplary aspect, the fire-retardant article will be able to withstand high-temperature (e.g., greater than 750°C, preferably greater than 1000°C, or more preferably greater than 1200°C) particle blasting without perforation caused by high-energy thermal runaway events. Surprisingly, chopped organic fibers can reduce or eliminate cracking of the exemplary cured inorganic coating at high temperatures.

[0027] The exemplary coating composition can be applied by spraying, painting, screen printing, etc. The exemplary coating composition can be a solvent-based coating or a water-based coating, preferably a water-based coating composition.

[0028] In some embodiments, the exemplary coating composition can be applied and dried in a planar configuration without a supporting material to form an exemplary fire-retardant article. This exemplary fire-retardant article can be incorporated into or surrounding a flammable energy storage device, such as a lithium-ion battery cell, module, or assembly, as seen in hybrid or electric vehicles or other electric transportation applications or locations. In other applications, the exemplary fire-retardant article can serve as a cover / packaging liner for the flammable energy storage device. The exemplary energy storage device can be used in battery storage applications such as grid energy storage, home energy storage, industrial energy storage, etc.

[0029] When the exemplary flame-retardant material is used in electric vehicle battery packs, its purpose is to prevent or mitigate fire from entering the vehicle's passenger compartment, allowing vehicle occupants sufficient time to evacuate the vehicle. Similarly, when the exemplary flame-retardant material is used in other battery storage applications, its purpose is to prevent or mitigate the spread of fire caused by battery failure events to surrounding structures, thereby reducing or mitigating damage to surrounding structures.

[0030] In some aspects, exemplary coatings may be applied to a substrate (such as a uniform layer on at least a portion of a two-dimensional substrate, such as flame-retardant paper (such as inorganic paper or mica-based paper), inorganic fabric, flame-retardant board (such as inorganic fiberboard or mica board or sheet), or a flame-retardant composite or multilayer material comprising one or more of the aforementioned materials) to form exemplary fire-retardant articles, which may be incorporated into or surrounded by flammable energy storage devices, such as lithium-ion battery cells, modules, or assemblies, for example, those found in hybrid or electric vehicles or other electric transportation applications or locations. In an alternative aspect, exemplary coatings may be applied to a substrate, such as a uniform layer on at least a portion of a three-dimensional substrate as described above, to form a flame-retardant article.

[0031] In some implementations, the two-dimensional substrate may be thermally and electrically insulating and in the form of inorganic insulating paper or board, as described in PCT Publication No. WO 2020 / 023357, which is incorporated herein by reference. Multiple sheets (i.e., layers or sublayers of inorganic paper) may be wet-laminated and pressed to obtain thermally and electrically insulating inorganic board or multilayer paper. The term "paper" refers to a flexible single-layer or multilayer material having sufficient flexibility to bend around a 3-inch mandrel. The term "board" refers to a relatively rigid material that can be flexed but not wrapped around a mandrel.

[0032] Exemplary inorganic fabrics may include E-glass fibers, R-glass fibers, ECR-glass fibers, basalt fibers, ceramic fibers, silicate fibers, Nextel fibers, steel wire, or combinations thereof. The fibers in the inorganic fabric may be chemically treated. The fabric may be, for example, woven or nonwoven mats, felts, cloths, knitted fabrics, stitched fabrics, crocheted fabrics, interwoven fabrics, or combinations thereof.

[0033] Exemplary multilayer materials may include at least one and at least a second layer, the at least one layer comprising inorganic particles or inorganic fibers or combinations thereof, and the at least second layer comprising a flame-retardant foam nonwoven mat or other porous material; a flame-retardant fabric material or a flame-retardant polymer material in the form of a membrane or nonwoven material. The inorganic fibers in the at least one layer comprising 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, borosilicate fibers, or combinations thereof. More specifically, the fiber material may include annealed melt-formed ceramic fibers, sol-gel formed ceramic fibers, polycrystalline ceramic fibers, alumina-silica fibers, and glass fibers (including annealed glass fibers or non-biodegradable fibers). Inorganic fabrics can be, for example, nonwoven mats, stitch-woven mats, needle-punched mats, chemically bonded mats or thermally bonded mats (single-component or bi-component fibers or powders) using inorganic or polymeric binders (both described in more detail below), or combinations thereof. Other fibers are also possible if they are subjected to the high temperatures generated in thermal events of lithium-ion batteries or other high-energy batteries.

[0034] In other applications, exemplary coating compositions may be applied directly to components of a battery module or battery pack, such as the aluminum cap of the battery pack.

[0035] The exemplary fire-retardant articles of the present invention should prevent heat from flowing from a faulty unit or module to an adjacent unit or module or to the passenger compartment. For example, when exposed to high temperatures on one side of a material, the exemplary fire-retardant articles should provide a high thermal gradient or temperature reduction across the material. Alternatively, the exemplary fire-retardant articles can be used as thermal barrier wraps or thermal barrier covers in electric vehicle battery packs, which can prevent or reduce the rate at which heat flows out of the battery pack.

[0036] Any of the exemplary flame-retardant articles described above may further include an adhesive layer disposed on a substrate or coated surface to attach the flame-retardant article to a surface requiring protection, such as the inner surface of a cover for a battery pack or module. The adhesive used for the adhesive layer may be a pressure-sensitive adhesive, a semi-structural B-stage hybrid adhesive, or a thermosetting adhesive to bond the flame-retardant article to the surface. The adhesive may be selected from acrylic adhesives, epoxy adhesives, silicone adhesives, metal silicate adhesives, or similar families of adhesives.

[0037] In some aspects of the invention, a pressure-sensitive adhesive may be bonded to the surface of the dried coating composition to adhere the dried coating composition to other substrates. In other embodiments, a curable adhesive such as sodium silicate, epoxy resin, silicone, or similar adhesive may be used to adhere the dried coating composition to other substrates.

[0038] The present invention may suitably include, consist of, or substantially consist of any of the disclosed or described elements. As used herein, the term "substantially consist of" does not exclude the presence of additional materials that do not significantly affect the desired properties of a given composition or product.

[0039] For example, an exemplary coating composition according to the invention may consist essentially of inorganic fillers, inorganic binders, and chopped organic fibers. This exemplary coating composition may further include additional materials, such as defoamers, surfactants, rheology modifiers, forming aids, pH-adjusting materials, or combinations thereof, which do not significantly affect the desired properties of the cured coating composition or the refractory article comprising the exemplary coating disposed on the surface of a product substrate. The inorganic fillers, inorganic binders, and chopped organic fibers of the coating composition may be any of the materials provided above in any of the suggested combinations.

[0040] After reading this specification, various modifications, equivalent processes, and multiple structures applicable to this invention will be apparent to those skilled in the art.

[0041] Example

[0042] These examples are merely for illustrative purposes and are not intended to limit the scope of the appended claims. Unless otherwise indicated, all parts, percentages, ratios, etc. in the examples and the rest of the specification are by weight.

[0043] Test methods

[0044] Mechanical properties

[0045] Flexural properties of coated glass cloth samples were measured before and after aging for 28 days at 85°C and 85% relative humidity on an Insight 5 tensile testing machine using a slightly modified ASTM D790 3-point flexural test. Aged samples were dried in an oven at 110°C for 1 hour prior to testing. The span between supports was 25.4 mm and the chuck speed was 5.1 mm / min. The measured flexural properties are shown as percentage change relative to the control material (CE 1) in Table 3 and also in Table 5.

[0046] Riot Control Test

[0047] Test specimens are tested for their resistance to hot particle blast to simulate high energy vehicle batteries under thermal runaway conditions. High energy batteries not only burn particles but also blast particles, which can also erode through materials at their high combustion temperatures.

[0048] After equilibrating the sample with a 1200°C flame, the sample is subjected to a series of 10-second sand blasts followed by a 5-second rest period. Sand blasting is performed at the substrate with a 25 psi compressed air pressure source; the sand is 120 grit alumina irregular media. These 10-second blasts with 5-second rests are repeated (with continuous flame application) until the flame and grit penetrate through the test sample. The coated side of the test sample sheet construction is oriented toward the hot particle blast. The number of blasts endured before penetrating the entire construction is recorded and shown in Table 4.

[0049] Material

[0050] 1 Potassium silicate solution (MR>3.2; 29% solids), purchased from PQ Corporation (Valley Forge, PA, USA).

[0051] 6 Potassium silicate solution (2.6<MR≤3.2; 39.2% solids), purchased from PQ Corporation (Valley Forge, PA, USA).

[0052] Sodium silicate (KSS) solution (2.6<MR≤3.2; 42.7% solids), purchased from PQ Corporation (Valley Forge, Pennsylvania, USA).

[0053] NALCO 2327 colloidal silica (40.0% solids), purchased from Nalco Chemical Company (Naperville, IL, USA)

[0054] P water-washed kaolin, available from Kamin LLC (Macon, GA, USA).

[0055] Poly(vinyl alcohol) fiber, NYCON-PVA RMS702 chopped polyvinyl alcohol fiber, 24 micrometers in diameter, 6 mm in length, purchased from Nycon Corporation (Fairless Hills, PA, USA).

[0056] Polypropylene fiber, Nycon ProCon M chopped polypropylene fiber, 38 micrometers in diameter, 19 mm in length, purchased from Nycon Corporation (Fairless Hills, Pennsylvania, USA).

[0057] Nylon fiber, Nycon RC nylon fiber, 9 micrometers in diameter, 3 mm in length, purchased from Nycon Corporation (Fairless Hills, Pennsylvania, USA).

[0058] Unifrax E-glass microfibers (6 micrometers in diameter, 6 mm in length), purchased from Unifrax (Tonawanda, NY, USA).

[0059] Suzorite 20S phlogopite (1300 micrometers median particle size), purchased from Imerys (Boucherville, Quebec, CA).

[0060] Suzorite 200HK phlogopite powder (60 micrometers median particle size), purchased from Imerys (Boucherville, Quebec, Canada).

[0061] E-glass cloth - 76g / m 2 basis weight, 0.072 mm thick, purchased from JPS Composite Materials (Anderson, South Carolina, USA).

[0062] Preparation of coating composition

[0063] Add all solid components to the mixing container and mix manually. Then add the inorganic binder and mix manually until the solids in the resulting slurry or paste are fully wetted. Then mix the mixture in a FlackTek high-speed mixer at 3,000 rpm for 2 minutes. The composition of each coating is provided in Table 1.

[0064] Table 1. Exemplary coating compositions in wet coating compositions

[0065]

[0066] Note: Due to the different densities of PVA fibers and glass fibers, the fiber volume fraction of Ex.3 (0.6% by weight of PVA fibers) is approximately the same as that of Ex.6 (1.2% by weight of glass fibers).

[0067] The coating compositions of Examples Ex.1 to Ex.4 and Comparative Examples CE 1 to CE 5 were applied to a thin e-glass cloth and dried at 100°C for 68 hours. The weight of the dried composition coating was approximately 1400 g / m². 2 .

[0068] Examples Ex.5, Ex.6, Ex.7, Ex.9, Ex.10, and Ex.11 were coated onto the release liner and dried at 120°C for 16 hours. The coating weight of Ex.5 and Ex.6 was approximately 1700 g / m². 2 The coating weight of Ex 7 is approximately 1300g / m². 2 The coating weight of Ex 9 is approximately 2600 g / m². 2 The coating weight of Ex 10 is approximately 1400 g / m². 2 Furthermore, the coating weight of Ex 11 is approximately 1300g / m². 2 .

[0069] The coating composition of Example Ex.8 was applied to flame-retardant paper, such as the flame-retardant paper described in PCT Publication No. WO 2020 / 023357. The coating weight of Ex.8 (excluding the flame-retardant paper) was 2000 g / m². 2 .

[0070] Table 2. Exemplary coating compositions in dried coatings are provided by weight percentage

[0071] Example adhesive filler fiber CE 1 28.7 71.3 CE 2 27.8 72.2 CE 3 28.7 69.3 2.0 CE 4 27.0 72.1 0.8 CE 5 27.0 72.6 0.4 CE 6 41.1 58.8 Ex1 28.7 70.8 0.5 Ex2 28.7 70.3 1.0 Ex3 28.7 69.3 2.0 Ex4 28.7 70.3 1.0 Ex5 43.1 56.8 0.1 Ex6 40.0 53.8 6.1 Ex7 60.2 38.0 1.8 Ex8 21.7 78.2 0.1 Ex9 17.0 82.9 0.1 Ex.10 41.1 58.4 0.5 Ex.11 41.1 57.3 1.6

[0072] Table 3. Flexural properties of exemplary coating compositions compared to Comparative Example CE 1 (without fiber fillers)

[0073]

[0074] Note: Fiber weight percentage is given as the amount of fiber in the wet coating composition.

[0075] As shown in Table 3, compared to the control sample CE 1, the addition of PVA fibers to the coating composition improved the flexural modulus and flexural stress at break of the coating composition, and was also higher than those of the coating composition containing glass fibers (Ex5). Furthermore, humidity aging data showed that the flexural modulus and flexural stress at break of the glass fiber composition were approximately the same as the control, while these properties of PVA fibers continued to be greater than those of the control (or glass fiber). Adding either type of fiber did not increase the flexural strain at break.

[0076] Table 4. Explosion-proof test results of exemplary coating compositions

[0077] Example <![CDATA[Coating weight (g / m 2 )]]> Endure the blast observe CE 2 1301 11 Ex4 1392 12 CE 4 1308 8 CE 5 1185 7 CE 6 1516 16 Cracking when exposed to heat Ex.10 1432 9 Cracking when exposed to heat Ex.11 1309 11 It did not crack when exposed to heat.

[0078] The comparison of Example Ex.4 in Table 4 with Comparative Examples CE 2, CE 4, and CE 5 shows that the addition of organic fibers did not adversely affect the number of explosions endured. Therefore, it has been found that the addition of organic fibers to the exemplary inorganic coating enhances the coating's flexibility while maintaining good explosion resistance and heat resistance.

[0079] Table 5. Flexural properties of exemplary coating compositions and their values ​​relative to comparative example CE 6

[0080]

[0081] Note: Fiber weight percentage is given as the amount of fiber in the wet coating composition.

[0082] While Comparative Example CE 6 showed a tendency to crack upon exposure to heat, Example Ex. 10 (which had a composition substantially the same as CE 6, except that Ex. 10 contained 0.5 wt% organic fibers in the dried coating) exhibited an increased flexural modulus. However, the Ex. 10 sample still cracked upon exposure to high temperatures (approximately 1200°C). As provided in Ex. 11, increasing the organic fibers in the dried coating to 1.6 wt% demonstrates that adding an appropriate level of organic fibers prevents cracking upon exposure to high temperatures while also providing good shatter resistance.

[0083] Therefore, organic fibers improve both the flexural modulus and strength of these inorganic coatings. Surprisingly, the incorporation of organic fibers into these inorganic systems has demonstrated unexpected high-temperature resistance and explosion-proof properties at temperatures far exceeding the thermal stability limits of organic fibers. Furthermore, even though organic fibers far exceed their thermal stability limits, they can also reduce the tendency of some inorganic coatings to crack at high temperatures.

Claims

1. A solvent-based coating composition for use in battery modules of electric vehicles, said solvent-based coating composition comprising: Solvent; Inorganic fillers; Inorganic binders, and Short-cut organic fibers, The coating composition comprises, based on the percentage of solids in the dried coating, 35% to 85% of the inorganic filler, 15% to 60% of the inorganic binder, and 0.1% to 6.5% of the chopped organic fibers. The inorganic filler is kaolin, metakaolin, or a mixture of kaolin and mica. The inorganic binder is selected from sodium silicate, potassium silicate, lithium silicate, and colloidal silica, and... The chopped organic fibers mentioned above are selected from polyvinyl alcohol fibers, polypropylene fibers, and nylon fibers. The coating, when applied to the substrate, is able to withstand high-temperature particle spraying at temperatures exceeding 1000°C without perforation caused by thermal runaway events in high-energy batteries.

2. The coating composition according to claim 1, wherein the inorganic filler is a mixture of kaolin and mica.

3. The coating composition according to claim 1, wherein the chopped organic fibers are selected from polyvinyl alcohol fibers and polypropylene fibers.

4. The coating composition according to claim 1, wherein the chopped organic fibers are composed of polyvinyl alcohol fibers.

5. The coating composition according to claim 1, wherein the chopped organic fibers increase the modulus of the cured coating formed by the coating composition by at least 24%.

6. The coating composition of claim 1, wherein the chopped organic fibers increase the fracture stress of the cured coating formed by the coating composition by at least 24%.

7. The coating composition according to claim 1, wherein when the coating is heated to a high temperature, the chopped organic fibers in the coating composition reduce cracking of the coating.

8. A refractory article wherein the coating composition according to claim 1 has been applied to a flat surface of a substrate, wherein the refractory article is capable of withstanding high-temperature particle blasting at temperatures greater than 1000°C without perforation caused by high-energy thermal runaway events.

9. The refractory product according to claim 8, wherein the high temperature is 1200°C.

10. The refractory product according to claim 8, wherein the substrate comprises one of glass cloth, basalt cloth, and mica board.

11. The refractory article according to claim 8, wherein the coating composition according to claim 1 has been applied to the three-dimensional surface of the substrate.

12. The refractory article according to claim 11, wherein the three-dimensional surface is the inner surface of the aluminum cover for the battery pack.

13. The refractory article according to claim 8 further includes a pressure-sensitive adhesive disposed on the cured coating surface, the cured coating surface being disposed on the substrate.

14. A coating composition for use in battery modules of electric vehicles, said coating composition comprising: Solvent; Inorganic fillers; Inorganic binders, and Short-cut organic fibers, The coating composition comprises, based on the percentage of solids in the dried coating, 35% to 85% of the inorganic filler, 15% to 60% of the inorganic binder, and 0.1% to 6.5% of the chopped organic fibers. The inorganic filler is kaolin, metakaolin, or a mixture of kaolin and mica. The inorganic binder is selected from sodium silicate, potassium silicate, lithium silicate, and colloidal silica, and... The chopped organic fibers mentioned above are nylon fibers. The coating, when applied to the substrate, is able to withstand high-temperature particle spraying at temperatures exceeding 1000°C without perforation caused by thermal runaway events in high-energy batteries.

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