Silicone-based fireproof sheet, its production process, and battery package having the sheet

Abstract

A silicone-based fireproof sheet, its production process, and a battery package using the sheet. The silicone-based fireproof sheet has a structure in which at least one heat-insulating filler selected from aerogel particles, hollow particles, and mesoporous particles is bound to a silicone-based polymer binder, and the amount of the heat-insulating filler is 5 to 40 mass% and the amount of the silicone-based polymer binder is 57.5 to 95 mass%, when the total mass of the solid content of the silicone-based fireproof sheet is 100 mass%.

Description

[Technical Field]

[0001] The present invention relates to a silicone fire-resistant sheet, a process for producing the same, and a battery package having the sheet, to the use of the silicone fire-resistant sheet in a battery package, and to a method for producing a battery package using the silicone fire-resistant sheet. [Background technology]

[0002] To control carbon dioxide emissions into the atmosphere and curb global warming caused by greenhouse gases, the production of electric vehicles (EVs) powered by rechargeable lithium-ion batteries (LIBs) has begun to surge in major regions around the world. To increase the driving distance per charge, EV battery manufacturers are targeting battery cathode and anode materials with higher energy density. Meanwhile, the adoption of nickel-based lithium metal oxides with higher Ni % increases the risk of thermal runaway propagation along with the increased energy density. To control the risk of thermal runaway propagation in battery packs with prismatic or pouch-shaped cells, a typical passive measure is to place an insulating sheet between two adjacent individual battery cells. When thermal runaway occurs in one cell, a so-called ignition cell, the temperature inside the cell rises sharply to 400°C or higher, e.g., 600°C, 800°C, or even 1000°C. Therefore, the surface of the cell heats up, and the temperature exceeds 350°C or higher, e.g., 550°C, 750°C, or 950°C. Heat-insulating sheets can slow the heat transfer from the hot surface of a flaming cell to adjacent healthy cells. A typical heat-insulating sheet used in the industry is an aerogel sheet, in which aerogel powder is compressed into a woven mat. The aerogel powder provides thermal insulation, and the woven mat holds the powder together in a sheet shape. However, due to its inherent low density and weak interparticle van der Waals forces, the aerogel powder on the sheet surface can easily disperse into the air during handling, causing contamination of the working environment. Therefore, there is a strong need in the EV battery industry for a method to develop a fire-resistant sheet with good thermal insulation performance and a clean working environment for the battery assembly process.

[0003] Silicone rubber can be ceramized at temperatures that cause its decomposition and condensation reaction. Adding insulating fillers, such as aerogel powder or hollow glass beads, to liquid silicone rubber, followed by curing and / or foaming, results in a sheet with silicone rubber as a matrix in which the insulating fillers are dispersed. If a cell experiences thermal runaway, the silicone matrix in the adjacent sheet may undergo ceramization, changing from soft rubber to a hard inorganic ceramic. Theoretically, the ceramized sheet can slow the heat diffusion from the igniting cell to adjacent healthy cells. Meanwhile, because the insulating filler is well bound by the silicone rubber, the sheet does not cause air pollution in the working environment. However, if the insulating filler is loaded too heavily into the liquid silicone rubber, the viscosity becomes too high, making it incompatible with the coating process. For mass-production pad or sheet manufacturing, an upper limit on the filler volume loading in the liquid silicone rubber is specified. Within this limit, the insulating performance of the final sheet may not be sufficient to prevent thermal runaway propagation. How to develop a fireproof sheet with silicone rubber to bind a sufficient load of pyrolytic filler remains a challenge.

[0004] This invention discloses a silicone-based fire-resistant sheet for battery packs that effectively prevents the propagation of thermal runaway from a burning cell to adjacent cells. This sheet uses silicone to bind an insulating filler, such as aerogel powder, with an insulating filler content of 5-40% by weight and a silicone content of >10% by weight or a polymer binder content of >50% by weight. The following is a more detailed summary of the related prior art that has been found. The prior art does not disclose battery packs that use silicone-bonded aerogel sheets, particularly sheets with an aerogel particle content of 5-40% by weight and a silicone content of >10% by weight or a polymer binder content of >50% by weight.

[0005] Chinese Patent Application Publication No. 108793932(A) claims a heat-insulating, energy-saving material and its preparation method, which are composed of the following raw materials, by weight: 30-60 parts silicon dioxide aerogel, liquid resin, 10-30 parts modified vitrified microbeads, 30-50 parts independent expanded perlite, 10-20 parts lightweight aggregate, 8-15 parts high-viscosity clay, 2-8 parts volcanic ash, 15-35 parts inorganic fiber, 2-10 parts dimethyl silicone oil, 1-5 parts water glass, 2-6 parts liquid resin, 0.5-1.5 parts dispersant, and 40-60 parts deionized water. The material of the present invention has a low thermal conductivity and low water absorption. The preparation method claims that water is first heated to 200°C, and then the liquid resin and silicone oil are added to the heated water. After the liquid resin is dissolved in the water, a filler is added to form a slurry. Unlike the prior art, the present invention claims a polymer binder content of >50 wt.% in the dry sheet to ensure mechanical strength. Calculations show that the maximum resin loading in the dry material in the prior art is 6 / (30+10+30+10+8+2+6+0.5)=6 / 96.5=6.2 wt.%. Clearly, the materials claimed in the prior art cannot be used for thermal runaway propagation prevention sheets in batteries. Furthermore, the prior art claimed a process in which a liquid resin was dissolved in hot water before adding a filler. Such a liquid resin would not be a silicone polymer, because silicone polymers cannot be dissolved in water.

[0006] US Patent No. 10,604,642 (B2) claims a solid insulating material essentially free of phyllosilicates, comprising: (a) 70 to 98 volume % of hydrophobic silica aerogel particles having an intrinsic density of 110 to 210 kg / m; and (b) 0.3 to 12 volume % of an organic binder formed by at least one organic polymer (b1) and at least one surfactant (b2) or by an amphiphilic organic polymer (b3), wherein these volume fractions are determined by image analysis of a thin section of the solid material and are given relative to the total volume of the material; and the aerogel particles have a particle size distribution with at least two maxima, a first maximum corresponding to an equivalent diameter (d) of less than 200 μm, preferably 25 μm to 150 μm, and a second maximum corresponding to an equivalent diameter (D) of 400 μm to 10 mm, preferably 500 μm to 5 mm. The prior art did not specify the organic binder as a silicone polymer. It taught water-soluble or water-dispersible polymers, such as acrylic or cellulose polymers, which cannot withstand the high temperatures encountered during battery thermal runaway. Unlike the prior art, the present invention discloses a silicone polymer as the majority of the polymeric binder, which reliably prevents thermal runaway propagation in the battery package. The silicone polymer in the binder must be >50 wt%, preferably >60 wt%, and more preferably >70 wt%. In some embodiments of the present invention, the volume percentage of the insulating filler is less than 60%. Furthermore, the present invention does not require aerogel particles with a particle size distribution exhibiting at least two maxima.

[0007] U.S. Patent Application Publication No. 20070238008(A1) claims an aerogel-based thermal management system and method for vehicles incorporating aerogel material to provide thermal insulation and heat protection. The aerogel material can be encapsulated in an encapsulating material such as a polymer, elastomer, or metal. Unlike the prior art, the present invention discloses a technology that uses a silicone emulsion to bind insulating fillers, such as aerogel powder, thus eliminating the need for encapsulation or encapsulating materials.

[0008] U.S. Patent No. 10,501,597 (B2) discloses a silicone rubber syntactic foam containing a silicone rubber binder and hollow glass beads, which partially or completely fills the open space of the battery module casing, partially or completely covers the battery cells, and / or partially or completely covers the module casing and, optionally, a lid covering the battery module casing. Unlike the prior art, the present invention discloses a sheet material containing >15 wt.% of a heat-insulating filler having a mesoporous or hollow structure. The sheet does not necessarily have to be a silicone rubber syntactic foam, as it is not limited to hollow glass beads. Furthermore, the present invention claims to mix a silicone emulsion with the filler, which binds the fillers together to form the final dry sheet. It has been found that the silicone emulsion is essential to meet processability requirements.

[0009] European Patent No. 3743466 (B1) claims a composition comprising a binder containing one or more siloxane polymers, silicone resins, silicone-based elastomers, and mixtures thereof, and a hydrophilic powder and / or gel selected from one or more amorphous porous hydrophilic silicas, wherein the binder is an aqueous solution, emulsion in water, or aqueous dispersion. Unlike the prior art, the present invention discloses a silicone sheet for preventing thermal runaway propagation, particularly in battery packages. The silicone sheet of the present invention contains an insulating filler that is not limited to porous hydrophilic silica. The insulating filler may be one selected from porous hydrophobic silica, hollow inorganic spheres, etc., or a combination thereof. Both porous hydrophobic silica and hollow glass beads are listed in comparative examples in the prior art. Furthermore, the prior art is silent about the final insulating performance of the composition. The present invention asserts that the final insulating performance of the silicone sheet must meet certain acceptable standards that specify the content of the insulating filler and silicone polymer in the total binder. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] Chinese Patent Application Publication No. 108793932(A) [Patent Document 2] US Patent No. 10604642(B2) [Patent Document 3] U.S. Patent Application Publication No. 20070238008(A1) [Patent Document 4] US Patent No. 10501597(B2) [Patent Document 5] European Patent No. 3743466(B1) Summary of the Invention [Problem to be solved by the invention]

[0011] The problem this invention aims to solve is how to better utilize insulating fillers, such as aerogel, in battery packs to prevent thermal runaway propagation in batteries without the work environment pollution problems of currently available aerogel blankets. The concept of this invention is a sheet (pad) of silicone polymer-bonded insulating filler, such as aerogel particles, with a sufficiently high filler loading for use in battery packs. The sheet also contains sufficient silicone binder so that the sheet is non-flammable and has good mechanical properties for handling. [Means for solving the problem]

[0012] After extensive investigation, the inventors discovered that the above problems can be solved by a silicone-based fireproof sheet having a structure in which at least one heat-insulating filler selected from aerogel particles, hollow particles, and mesoporous particles is bound to a silicone-based polymer binder, wherein the amount of the heat-insulating filler is 5 to 40 mass% and the amount of the silicone-based polymer binder is 57.5 to 95 mass%, when the total mass of the solids content of the silicone-based fireproof sheet is 100 mass%, and thus arrived at the present invention.

[0013] In the above-described silicone-based fireproof sheet, the average size or diameter of the insulating filler is not particularly limited, but is typically in the range of 1 μm to 1.20 mm, and at least 50% by weight of the silicone-based polymer binder is a cured silicone product. In some embodiments of the present disclosure, the aerogel particles have an average particle size in the range of 0.01 to 1.0 mm, and the amount is in the range of 15 to 35% by weight, based on the total weight of the solids of the silicone-based fireproof sheet. In some embodiments of the present disclosure, the silicone-based polymer binder is a water-based silicone polymer binder. In some embodiments of the present disclosure, the silicone-based polymer binder contains a water-based silicone polymer binder containing colloidal silica through a condensation curing reaction using an alkoxysilane as a crosslinker. In some embodiments of the present disclosure, the silicone-based polymer binder further comprises at least one selected from the group consisting of a flame retardant additive, a curing catalyst, a rheology modifier, an antifoaming additive, a wetting additive, a surface treatment agent, a colorant, a filler other than a heat insulating filler, an antioxidant additive, a biocide, an ultraviolet (UV) stabilizing additive, a biocide, and an adhesion promoting additive. In some embodiments of the present disclosure, the silicone-based fireproof sheet can be applied to a battery package.

[0014] The present disclosure further provides a battery packaging structure in which the silicone-based fire-resistant sheet is disposed completely or partially within the space between at least two adjacent individual battery cells. In some embodiments of the present disclosure, the battery has a prismatic or pouch-like shape.

[0015] In the battery packaging structure described above, the silicone-based fireproof sheet is a silicone-based product sheet that is cured before being placed in the space between at least two adjacent individual battery cells. In some embodiments of the present disclosure, the silicone-based fireproof sheet is a cured silicone-based product through a curing reaction of a curable silicone-based composition in the space between at least two adjacent individual battery cells. The preferred shape of the battery cells is preferably a prismatic or pouch-like shape that is protected by the silicone-based fireproof sheet.

[0016] The present disclosure further provides an aqueous curable silicone-based composition that is formed into the silicone-based fire-resistant sheet through a curing reaction, the composition comprising: (A) a curable silicone polymer binder containing at least 50% by mass of a curable silicone polymer in an amount ranging from 57.5 to 95% by mass, where the total mass of the solid content of the silicone fireproof sheet is 100% by mass; (B) at least one heat insulating filler selected from aerogel and hollow particles in an amount ranging from 5 to 40% by mass, when the total mass of the solid content of the silicone-based fireproof sheet is taken as 100% by mass; (C) a curing agent for said component (A); (D) water, and optionally (E) at least one selected from the group consisting of flame retardant additives, curing catalysts, rheology modifiers, antifoaming additives, wetting additives, surface treatment agents, colorants, fillers other than the heat insulating filler, antioxidant additives, biocides, ultraviolet (UV) stabilizing additives, and adhesion promoting additives, when the total mass of the solid content of the silicone fireproof sheet is taken as 100 mass %; The present invention provides an aqueous curable silicone-based composition comprising:

[0017] In the aqueous curable silicone composition, component (A) is a silicone polymer binder containing a curable silicone and another curable polymerizable material in a weight ratio of 50:50 to 100:00. In some embodiments of the present disclosure, component (A) of the silicone polymer binder is emulsified or uniformly dispersed in water (D).

[0018] The present disclosure further provides a method for producing the silicone-based fireproof sheet, comprising the steps of: Step (I): applying the aqueous curable silicone-based composition as a wet slurry layer onto a substrate, optionally having a release layer for the coating; Step (II): Following step (I), forming the silicone-based fireproof sheet by removing water from the applied aqueous curable silicone-based composition at a temperature of up to 140°C; The present invention provides a method comprising:

[0019] In some embodiments of the present disclosure, the thickness of the wet slurry layer of the aqueous curable silicone composition in step (I) is in the range of 0.2 to 10.0 mm. The method for producing the silicone fire retardant sheet further comprises the step of controlling the viscosity and / or flowability of the aqueous curable silicone composition by adding water and / or a rheology modifier before or at the same time as step (I).

[0020] Furthermore, the present invention provides a method for producing a battery packaging structure as claimed in claim 8, comprising the following steps: Step (BI): completely or partially filling a space between at least two adjacent individual battery cells with an aqueous curable silicone-based composition as a wet slurry layer; Step (B-II): Following step (BI), forming the silicone-based fireproof sheet in the space between at least two adjacent individual battery cells by removing water from the applied aqueous curable silicone-based composition at a temperature of up to 140°C; The present invention provides a method comprising:

[0021] Effect of the invention The present invention allows for the production of silicone-based fire-resistant sheets that allow for the addition of insulating fillers at loadings of >15% by weight or higher, creating a crosslinked polysiloxane backbone as a binder matrix in the final sheet. Additionally, silicone-bonded insulating sheets can be placed within battery packs to isolate hot spots or igniting cells and prevent / delay heat propagation to surrounding areas or cells.

[0022] It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed. [Brief explanation of the drawings]

[0023] [Figure 1] FIG. 1 is a schematic diagram of an apparatus for testing the thermal insulation performance of a silicone-based fire-resistant sheet according to the present disclosure. [Figure 2] 1 shows rear surface temperature curves of Examples IE-1 to IE-3 and Comparative Example CE1 in the present disclosure, the curves being, from top to bottom, the rear surface temperature curves of CE1, IE1, IE2, and IE3, respectively. [Figure 3] 10 is a backside temperature curve of Comparative Example CE2 in the present disclosure. [Figure 4] 1 shows backside temperature curves for Examples IE4 and IE5 in the present disclosure, where the curves are, from top to bottom, the backside temperature curves for IE4 and IE5, respectively. DETAILED DESCRIPTION OF THE INVENTION

[0024] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. As disclosed herein, "and / or" means "and, or alternatively" or "in addition, or alternatively." All ranges include the endpoints unless otherwise indicated.

[0025] All phrases containing parentheses refer to either or both of the substance or absence thereof contained within the parentheses. For example, the phrase "(water-based) polyurethane" includes, in the alternative, polyurethane and water-based polyurethane.

[0026] As used herein, the term "sheet" or "sheet form" refers to a flat product in the form of a pad or sheet having a thickness. Generally, "sheet" or "sheet form" includes pad forms, sheet forms, and other flat products having various thicknesses.

[0027] As used herein, the term "thickness" refers to the average of at least three measurements of a dry sheet (e.g., a sheet having a thickness of 0.8 to 1.2 mm) as measured using an Ames Gage, Model 13C-B2600 (Ames Corporation, Waltham Mass.).

[0028] As used herein, the terms "aerogel" and "aerogel material" describe a class of structures that have low density, open-cell structure, high surface area, and nanometer-scale pore sizes. Aerogel materials can be provided in at least powder, granule, bead, and other suitable forms, and include inorganic, organic, and hybrid organic-inorganic compositions, or some combination of the above forms and / or compositions.

[0029] As used herein, the term "aerogel" refers to a gel obtained in a known manner by the sol-gel route after drying. This term encompasses both suitable aerogels obtained by supercritical drying of formed gels, as well as gels commonly called "xerogels" obtained by evaporative drying at atmospheric pressure. Xerogels are highly advantageous when considering large-scale production of the materials of the invention due to their low cost, while aerogels exhibit more advantageous technical properties but are more expensive to produce.

[0030] The term "true density" is the quotient obtained by dividing the mass of a sample, such as the mass of a glass bubble, by the true volume of that mass of glass bubbles, as measured by a gas pycnometer. The "true volume" is the total volume of the glass bubbles, not the bulk volume.

[0031] As used herein, the terms "polymer" or "macromolecule" refer to polymers made from one or more different monomers, such as copolymers, terpolymers, tetrapolymers, pentapolymers, and the like, alternatively, and may be random, block, graft, sequential, or gradient polymers.

[0032] As used herein, the term "solids" or "solids content" refers to any material in a composition other than water and solvent, if present.

[0033] As used herein, unless otherwise indicated, the term "average diameter" or "average size" refers to the weight- or volume-average diameter as determined by light scattering (LS) using a BI-90 particle size analyzer (Brookhaven Instruments Corp. Holtsville, NY), or the weight- or volume-average length of irregularly shaped particles as measured by image analysis from images captured by either an instrument such as a SEM, TEM, or optical microscope.

[0034] As used herein, the phrase "% by mass" refers to mass percent or % by mass, and the phrase "% by weight" refers to weight percent or % by weight.

[0035] To effectively prevent thermal runaway propagation within a battery pack, it is highly preferable that the insulating inorganic filler content in the silicone-based fire sheet be greater than 15% by weight. In the present disclosure, silicone-based polymer binders (emulsions) allow for higher loadings of insulating filler (e.g., greater than 15% by weight) in the silicone-based fire sheet. Liquid silicone rubbers and resins, as well as solutions of silicone rubbers and resins in organic solvents, are candidates for dispersing aerogel particles therein, followed by a drying and / or curing process to produce silicone-bonded aerogel sheets. The organic solvent in the silicone polymer or resin solution must be contained in special equipment during the sheet manufacturing process. When liquid silicone rubbers or resins are used, the mixture viscosity may become high in some instances, especially when the aerogel particle loading level is very high. Due to the high viscosity, it is extremely difficult to process such high loadings of insulating filler in such liquid silicone rubbers or resins. By using a silicone-based polymeric binder emulsion, the viscosity of the wet slurry obtained after mixing the silicone-based polymeric binder emulsion with the insulating filler can be more easily fine-tuned to meet processability requirements. Furthermore, by using a silicone-based polymer as the majority of the polymeric binder, a crosslinked polysiloxane skeleton is created as the binder matrix in the silicone-based fireproof sheet. A well-crosslinked polysiloxane allows for good thermal stability up to 350°C, ensuring thermal insulation performance below that temperature. The well-crosslinked polysiloxane skeleton can be fine-tuned to favor ceramification at temperatures above 350°C to produce an inorganic ceramic material, allowing the insulating fillers to remain bonded to each other and providing excellent thermal insulation performance at temperatures above 350°C, such as 450°C, 650°C, 750°C, and even 950°C. To meet mechanical strength requirements, the total polymeric binder in the silicone-based fireproof sheet must be ≥ 57.5% by weight. To meet the thermal stability performance, the silicone-based polymer in the total polymeric binder must be ≧50 wt %, preferably ≧60 wt %, more preferably ≧70 wt %.

[0036] According to the present invention, the silicone-based fireproof sheet has a structure in which at least one heat insulating filler selected from aerogel particles, hollow particles, and mesoporous particles is bonded to a silicone-based polymer binder in an amount of 5-40 mass%, 5-35 mass%, 5-30 mass%, 5-25 mass%, 5-20 mass%, 5-15 mass%, 5-10 mass%, 10-40 mass%, 10-35 mass%, 10-30 mass%, 10-25 mass%, 10-20 mass%, 10-15 mass%, 15-40 mass%, 15-35 mass%, 15-30 mass%, 15-25 mass%, 15-20 mass%, or 15-20 mass%. %, 20 to 40 mass%, 20 to 35 mass%, 20 to 30 mass%, 20 to 25 mass%, 25 to 40 mass%, 25 to 35 mass%, 25 to 30 mass%, 30 to 40 mass%, 30 to 35 mass%, or 35 to 40 mass%, and the amount of the cured silicone polymer binder is in the range of 57.5 to 95 mass%, 57.5 to 90 mass%, 57.5 to 85 mass%, 57.5 to 80 mass%, 5 7.5-75 mass%, 57.5-70 mass%, 57.5-65 mass%, 57.5-60 mass%, 60-95 mass%, 60-90 mass%, 60-85 mass%, 60-80 mass%, 60-7 5% by mass, 60-70% by mass, 60-65% by mass, 65-95% by mass, 65-90% by mass, 65-85% by mass, 65-80% by mass, 65-75% by mass, 65-70% by mass, 70-95 quality %, 70 to 90 mass%, 70 to 85 mass%, 70 to 80 mass%, 70 to 75 mass%, 75 to 95 mass%, 75 to 90 mass%, 75 to 85 mass%, 75 to 80 mass%, 80 to 95 mass%, 80 to 90 mass%, 80 to 85 mass%, 85 to 95 mass%, 85 to 90 mass%, or 90 to 95 mass%, and the total mass of the solids content of the silicone fireproof sheet is 100 mass%.

[0037] In the present invention, the insulating filler includes at least one selected from aerogel particles, hollow particles, and mesoporous particles. Specifically, the insulating filler used in the present invention may include, but is not limited to, aerogel powder, hollow glass beads, perlite, hollow ceramic beads, mesoporous particles, microporous particles, a mixture of mesoporous particles with different pore sizes ranging from 2 nm to 50 nm, and other inorganic fillers with mesoporous or hollow-cell structures. In some embodiments, the insulating filler in the dry sheet has a loading of more than 15% by weight, 15% to 30% by weight, 15% to 25% by weight, 15% to 20% by weight, 20% to 30% by weight, 20% to 25% by weight, or 25% to 30% by weight.

[0038] In an embodiment of the present disclosure, the average diameter or size of the insulating filler is 1 μm (=0.001 mm) to 1.20 mm, 10 μm (=0.01 mm) to 1.20 mm, 0.01 to 1.20 mm, 0.01 to 1.00 mm, 0.01 to 0.80 mm, 0.01 to 0.60 mm, 0.01 to 0.40 mm, 0.01 to 0.20 mm, 0.03 to 1.20 mm, 0.20 to 1.00 mm, 0.20 to 0.80 mm, 0.20 to 0.60 mm, 0.20 to 0.40 mm, 0.40 to 1.20 mm, 0.40 to 1.00 mm, 0.40 to 0.80 mm, 0.40 to 0.60 mm, 0.60 to 1.20 mm, 0.60 to 1.00 mm, 0.60 to 0.80 mm, 0.80 to 1.20 mm, 0.80 to 1.00 mm, or 1.00 to 1.20 mm.

[0039] In embodiments of the present disclosure, aerogel particles, hollow particles, and mesoporous particles having an average diameter or size ranging from 0.05 to 1.0 mm, 0.05 to 0.8 mm, 0.05 to 0.6 mm, 0.05 to 1.0 mm, or 0.05 to 0.8 mm are bound together in a condensation-cured silicone polymer binder. The preferred amount of the aerogel particles is 15 to 35%, 15 to 30%, 15 to 25%, or 15 to 20% by weight, based on 100% by weight of the total solids content of the silicone fireproof sheet.

[0040] In the present invention, aerogel particles, hollow particles, and mesoporous particles have a density of less than 0.25 grams per cubic centimeter (g / cc), 0.001 g / cc to 0.25 g / cc, 0.05 g / cc to 0.20 g / cc, 0.05 g / cc to 0.15 g / cc, 0.05 g / cc to 0.10 g / cc, 0.10 g / cc to 0.25 g / cc, 0.10 g / cc to 0.20 g / cc, 0.10 g / cc to 0.15 g / cc, and 0.15 g / cc. and may have a thermal conductivity of less than 0.1 W / mK, 0.01 W / mK to 0.1 W / mK, 0.01 W / mK to 0.06 W / mK, 0.01 W / mK to 0.03 W / mK, 0.03 W / mK to 0.1 W / mK, 0.03 W / mK to 0.06 W / mK, or 0.06 W / mK to 0.1 W / mK.

[0041] In the present invention, aerogel particles can be provided in any suitable form, such as granules, powders, and beads. The chemical composition of the aerogel particles can be inorganic, organic, hybrid organic-inorganic, or any combination thereof. Any combination of the above forms and / or compositions can be used in the present invention. Optionally, the aerogel particles can be coated with one or more materials, such as a polymer or elastomer, or treated with a treating agent, such as a silane. A variety of different aerogel compositions can be used, including inorganic, organic, and hybrid organic-inorganic compositions. Inorganic aerogels are generally based on metal oxide compounds, including, but not limited to, silica, titania, zirconia, alumina, hafnia, yttria, or various carbides, nitrides, or any combination thereof. Organic aerogels can be based on compounds including, but not limited to, urethanes, resorcinol formaldehyde, polyimides, polyacrylates, chitosan, polymethyl methacrylate, members of the acrylate family of oligomers, trialkoxysilyl-terminated polydimethylsiloxanes, polyoxyalkylenes, polyurethanes, polybutadiene, members of the polyether family of materials, or combinations thereof. Examples of organic-inorganic hybrid aerogels include, but are not limited to, silica-PMMA, silica-chitosan, or combinations of the aforementioned organic and inorganic compounds. In certain circumstances, organic polymers or organic-inorganic hybrid polymers can be thermally treated to yield carbon- or inorganic-based mesoporous or microporous materials, including aerogels.

[0042] The term "hollow particles" is understood to mean particles having a high density or low porosity shell and free space within the shell. The hollow particles according to the present invention have a shell whose thickness can be controlled. In the present invention, hollow particles can include hollow glass particles and hollow ceramic beads.

[0043] In the present invention, mesoporous particles have pore diameters in the range of 2 nm to 50 nm, a large specific surface area, and a three-dimensional pore structure. According to their chemical composition, mesoporous materials are generally classified into silicon-based and non-silicon-based mesoporous materials. Non-silicon-based mesoporous materials include transition metal oxides, phosphates, and sulfides, such as silicon aluminophosphate (SAPO), which is formed after a portion of the P in an aluminophosphate-based molecular sieve material is replaced by Si, and activated carbon, which has a large internal surface area and a high pore volume.

[0044] In silicone-based fireproof sheets, the silicone-based polymeric binder may be fully or partially cured via a condensation reaction, e.g., a fully cured or semi-cured silicone-based polymeric binder. Alternatively, the silicone-based polymeric binder may be a curable, water-based, or solvent-based binder resin (i.e., in an uncured state) that can be applied to form a sheet product. Alternatively, the silicone-based polymeric binder may be cured via a hydrosilylation reaction, a condensation reaction, or a free-radical initiated curing reaction. In a preferred embodiment, the silicone-based polymeric binder is cured. In a preferred embodiment, the silicone-based polymeric binder is water-based (i.e., aqueous) for environmental friendliness. In a more preferred embodiment, the silicone-based polymeric binder may further contain a colloidal silica component. Most preferably, the silicone-based polymeric binder can be cured via a condensation reaction between a silicone having hydrolyzable groups and a hydrolyzable silane curing agent or other condensation reaction agent.

[0045] Silicone-based polymeric binders can be elastomeric or rigid, i.e., have a glass transition temperature above room temperature. Silicones typically contain four representative categories of structural units: M(RSiO-), D(-OSiR2O-), and T(RSiO-). 3 / 2 -), and Q(SiO 4 / 2) where R is a saturated or unsaturated alkyl or aryl group and the subscript n / 2 refers to the number of oxygen atoms bridging and sharing two silicon atoms. Silicone rubbers are based mainly on D structures, while resins are more based on T and Q structural units.

[0046] In embodiments of the present disclosure, at least 50%, at least 55%, at least 60%, at least 65%, or at least 70% by weight of the silicone-based polymeric binder is a cured silicone product.

[0047] In an embodiment of the present disclosure, the silicone-based polymer binder is a water-based silicone polymer binder resin. In a preferred embodiment of the present disclosure, the silicone-based polymer binder contains a water-based silicone polymer binder containing colloidal silica through a condensation cure reaction using an alkoxysilane as a crosslinker. The colloidal silica may be dispersed in water before mixing with the water-based silicone polymer binder so that the weight ratio of colloidal silica (solid content) to silicone polymer in the silicone emulsion is ≦0.5. A loading of >0.5 may result in the rubber matrix becoming too hard.

[0048] In an embodiment of the present disclosure, the silicone-based polymer binder further comprises at least one selected from the group consisting of a flame-retardant additive, a curing catalyst, a silicone crosslinker, a rheology modifier, an antifoaming additive, a wetting additive, a surface treatment agent, a colorant, a filler other than the insulating filler, an antioxidant additive, an ultraviolet (UV) stabilizing additive, a biocide, and an adhesion promoter additive. In the present invention, the flame-retardant additive comprises a halogenated flame-retardant additive and / or a non-halogenated flame-retardant additive. Examples of the halogenated flame-retardant additive include brominated polymers or oligomers, brominated styrene-butadiene-styrene copolymers (e.g., FR-122P used in the examples), and the like, preferably a combination of a brominated flame-retardant additive and antimony trioxide to form a Br-Sb synergistic system. Examples of the non-halogenated flame-retardant additive include ammonium polyphosphate, melamine polyphosphate, aluminum hydroxide, magnesium hydroxide, amorphous phosphorus, and expandable graphite. In the present invention, the flame retardant additive may be dispersed in the silicone-based polymeric binder (i.e., the polymer matrix) at a loading ranging from 0 to 60% by weight of the dry sheet, or may be distributed throughout the silicone-based polymeric binder. Flame retardant additives with loadings greater than 60% by weight may result in insufficient thermal insulation performance required for battery fire protection applications. Rheology modifiers, for example, in amounts of 0 to 2% by weight in the wet slurry, are used to fine-tune the viscosity of the wet slurry. Silicone crosslinkers may be included in amounts of 0 to 5% by weight in the wet slurry, such as TEOS (tetraethoxysilane) or NPOS (n-propyl orthosilicate). Curing catalysts include dioctyltin dilaurate, depending on the curing chemistry. Antifoam additives, for example, in amounts of 0 to 5% by weight in the wet slurry, are used to remove air bubbles in the wet slurry. Wetting additives are used for surface wetting of hydrophobic fillers. Colorants or color masterbatches can impart desired colors to the silicone-based fire protection sheet. Fillers other than the insulating filler include, but are not limited to, silica, CaCO3, and hydromagnesite.

[0049] In the present invention, the aqueous silicone polymer binder may be curable and includes a polyorganosiloxane containing at least two silicon-bonded hydroxyl or hydrolyzable groups in each molecule. The molecular structure of the polyorganosiloxane may be linear, cyclic, branched, dendritic, or network, with linear or partially branched linear being preferred. The hydroxyl or hydrolyzable groups may be present at the terminal positions of the molecular chain, at side chain positions of the molecular chain, or both. Examples of hydrolyzable groups include alkoxy groups, alkoxyalkoxy groups, acetoxy groups, oxime groups, enoxy groups, amino groups, aminoxy groups, and amido groups, and examples of C groups include methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, t-butoxy, hexyloxy, cyclohexyloxy, octyloxy, and decyloxy. 1~10 C such as alkoxy, methoxymethoxy, methoxyethoxy, ethoxymethoxy, methoxypropoxy, etc. 2~10 Alkoxyalkoxy is preferred.

[0050] The unsubstituted monovalent hydrocarbyl group and the substituted monovalent hydrocarbyl group are examples of silicon-bonded organic groups other than hydroxyl or hydrolyzable groups. From the viewpoint of emulsification-promoting action, the unsubstituted monovalent hydrocarbyl group is preferably C 1~10 Unsubstituted monovalent hydrocarbyl groups are preferred. Unsubstituted monovalent hydrocarbyl groups include C groups such as methyl, ethyl, n-propyl, isopropyl, butyl, t-butyl, hexyl, octyl, and decyl. 1~10 Alkyl; cyclopentyl, cyclohexyl, etc. 3~10 Cycloalkyl; vinyl, allyl, 5-hexenyl, 9-decenyl, etc. 2~10 Alkenyl; C such as phenyl, tolyl, xylyl 6~10 Aryl; and C such as benzyl, methylbenzyl, and phenethyl 7~10 Examples include aralkyl, among which C 1~10 Alkyl, C 6~10 Aryl, and C 2~10 Alkenyl is preferred, with methyl and phenyl being especially preferred.

[0051] The substituted monovalent hydrocarbyl groups may be any of the unsubstituted monovalent hydrocarbyl groups described above, particularly C 1~10 Examples include groups provided by substituting all or part of the hydrogen atoms in the alkyl and phenyl with halogen atoms such as fluorine and chlorine; epoxy functional groups such as glycidyloxy and epoxycyclohexyl; methacryl functional groups such as methacryloxy; acryl functional groups such as acryloxy; amino functional groups such as amino group, aminoethylamino, phenylamino and dibutylamino; sulfur-containing functional groups such as mercapto group and tetrasulfide group; or substituents such as alkoxy, hydroxycarbonyl and alkoxycarbonyl.

[0052] Illustrative examples of substituted monovalent hydrocarbyl groups include 3,3,3-trifluoropropyl, perfluorobutylethyl, perfluorooctylethyl, 3-chloropropyl, 3-glycidoxypropyl, 2-(3,4-epoxycyclohexyl)ethyl, 5,6-epoxyhexyl, 9,10-epoxydecyl, 3-methacryloxypropyl, 3-acryloxypropyl, 1,1-methacryloxyundecyl, 3-aminopropyl, N-(2-aminoethyl)aminopropyl, 3-(N-phenylamino)propyl, 3-dibutylaminopropyl, 3-mercaptopropyl, 3-hydroxycarbonylpropyl, methoxypropyl, and ethoxypropyl.

[0053] There are no particular limitations on the viscosity of the silicone polymer binder at 25° C. However, taking into consideration the strength of the cured sheet of the present invention and its handling characteristics during production, the viscosity of the silicone polymer binder at 25° C. is preferably 50 mPa·s to 2,000,000 mPa·s, more preferably 100 mPa·s to 500,000 mPa·s, and even more preferably 500 mPa·s to 100,000 mPa·s.

[0054] The silicone polymer binder may be a diorganopolysiloxane in which both molecular chain ends are capped with hydroxyl groups. Such diorganopolysiloxane in which both molecular chain ends are capped with hydroxyl groups has the general formula HO(RSiO) m H, which represent the same silicon-bonded unsubstituted or substituted monovalent hydrocarbyl groups other than hydroxyl or hydrolyzable groups, and C 1~10 Alkyl, C 6~10 Aryl, and C 2~10 Alkenyl is preferred, with methyl and phenyl being especially preferred. The subscript m is an integer having a value of at least 2, preferably a number that provides a viscosity at 25°C of 50 mPa·s to 2,000,000 mPa·s.

[0055] In the present invention, preferred aqueous silicone polymeric binders that can be cured through a condensation reaction are commercially available. For example, DOWSIL® 8005 aqueous resin, DOWSIL® 8004 aqueous resin, and Dowsil® IE-2404 can be purchased from DOW SILICONES CORPORATION or its affiliates. Such curable silicone polymeric binders or mixtures thereof can be cured by removing water under heating at temperatures up to 140°C.

[0056] In the present invention, the binder, when used, may be a mixture of a curable silicone-based polymer binder and another organic polymer binder resin / rubber composition. In an embodiment of the present invention, the other organic polymer binder resin / rubber composition includes, but is not limited to, polyurethane binders, polyacrylate / polyacrylic acid binders, epoxy resin binders, phenolic resin binders, polyamide binders, polyester binders, polyolefin binders, polystyrene binders, and ethylene-vinyl acetate copolymers. In a preferred embodiment, the amount of the curable silicone-based polymer binder is at least 50% by weight, at least 55% by weight, at least 60% by weight, at least 65% by weight, at least 70% by weight, at least 75% by weight, at least 80% by weight, or at least 85% by weight of the mixture. Specifically, an aqueous mixture of the silicone-based polymer binder and polyurethane binder is preferably used in the present invention. The aqueous binder resin mixture can be cured by removing water under heating at a maximum temperature of 140°C.

[0057] In the present invention, the aqueous curable silicone composition can be formed into the silicone fireproof sheet through a curing reaction, and the silicone fireproof sheet can be formed into the silicone fireproof sheet by (A) A curable silicone polymer binder containing at least 50 mass%, at least 55 mass%, at least 60 mass%, at least 65 mass%, or at least 70 mass% of a curable silicone polymer, wherein the curable silicone polymer is 57.5 to 95 mass%, 57.5 to 90 mass%, 57.5 to 85 mass%, 57.5 to 80 mass%, 57.5 to 75 mass%, 57.5 to 70 mass%, 57.5 to 65 mass%, 57.5 to 60 mass%, 60 to 95 mass%, 60 to 90 mass%, 60 to 85 mass%, 60 to 80 mass%, or 60 to 75 mass% , 60-70 mass%, 60-65 mass%, 65-95 mass%, 65-90 mass%, 65-85 mass%, 65-80 mass%, 65-75 mass%, 65-70 mass%, 70-95 mass%, 70-90 mass%, 70-85 mass%, 70-80 mass%, 70-75 mass% %, 75-95% by mass, 75-90% by mass, 75-85% by mass, 75-80% by mass, 80-95% by mass, 80-90% by mass, 80-85% by mass, 85-95% by mass, 85-90% by mass, or 90-95% by mass, and (B) 5-40% by mass, 5-35% by mass, 5-30% by mass, 5-25% by mass, 5-20% by mass, 5-15% by mass, 5-10% by mass, 10-40% by mass, 10-35% by mass, 1 0-30% by mass, 10-25% by mass, 10-20% by mass, 10-15% by mass, 15-40% by mass, 15-35% by mass, 15-30% by mass, 15-25% by mass, 15-20% by mass %, 20-40 mass%, 20-35 mass%, 20-30 mass%, 20-25 mass%, 25-40 mass%, 25-35 mass%, 25-30 mass%, 30-40 mass%, 30-35 mass%, 35-40 mass%, and / or 35-40 mass% of hollow particles, including mesoporous particles and / or microporous particles, such as aerogels; (C) a curing agent for said component (A); (D) water, and optionally (E) at least one selected from the group consisting of flame retardant additives, curing catalysts, rheology modifiers, antifoaming additives, wetting additives, surface treatment agents, colorants, fillers other than the insulating filler, antioxidant additives, ultraviolet (UV) stabilizing additives, biocides, and adhesion promoting additives; Including, This is when the total mass of the solid content of the silicone fireproof sheet is taken as 100 mass %.

[0058] In an embodiment of the present disclosure, component (A) is a silicone-based polymer binder containing a curable silicone and other curable polymerizable materials, and the other curable polymerizable materials are present in an amount of 0% to 30% by mass, 10% to 30% by mass, 20% to 30% by mass, 0% to 20% by mass, 0% to 10% by mass, 20% to 30% by mass, or 10% to 20% by mass, based on the total mass of the silicone-based polymer binder. Prior to mixing, component (A) of the silicone-based polymer binder may first be emulsified or uniformly dispersed in water (D).

[0059] Examples of the curing agent (C) of the component (A) include crosslinkable silanes and condensation curing agents. Typically, hydrolyzable silanes (e.g., TEOS (tetraethoxysilane), MTMS (methyltrimethoxysilane), NPOS (n-propyl orthosilicate), and mixtures thereof) are preferably used as the component (C).

[0060] In the present invention, the method for producing the silicone-based fireproof sheet comprises: (1) mixing a silicone-based polymer binder emulsion with a heat-insulating filler in an aqueous solution to form a wet slurry or paste; (2) applying a wet slurry or paste onto a substrate, such as a release paper, wherein the wet slurry or paste layer has a thickness in the range of 0.2 mm to 10 mm, 0.2 mm to 5 mm, or 2 mm to 10 mm (in the present invention, thicknesses <0.2 mm may be prone to pinhole formation in the wet film, and thicknesses >10 mm may make it difficult to remove water and form a crack-free dry sheet); (3) removing water by subjecting the wet film to temperatures up to 140°C and circulating air to form a dry sheet; temperatures above 140°C may result in cracks and other defects on the sheet; Includes.

[0061] In an embodiment of the present invention, the method for producing the silicone-based fire-resistant sheeting may further include adding one or more ingredients selected from colloidal silica, crosslinking agents, catalysts, rheology modifiers, antifoaming additives, wetting additives, colorants, other fillers, biocides, antioxidant additives, and UV stabilizers to the silicone-based polymer binder emulsion before mixing with the insulating filler in the aqueous solution.

[0062] In an embodiment of the present invention, the method for producing the silicone-based fire-resistant sheeting may further include, after adding the insulating filler to the silicone-based polymer binder emulsion, adding one or more components selected from colloidal silica, crosslinking agents, catalysts, rheology modifiers, antifoaming additives, wetting additives, colorants, other fillers, biocides, antioxidant additives, and UV stabilizers to the wet slurry or paste.

[0063] In an embodiment of the present invention, the method for producing the silicone-based fire-resistant sheet may further include adding a small amount of water to the wet slurry or paste to fine-tune its fluidity. The amount of water added is intended to ensure slightly better fluidity of the homogeneous slurry for application. If the fluidity of the slurry is sufficient to apply a specific wet film thickness, adding water may not be necessary, depending on the solids content of the emulsion and the filler loading. If the filler loading exceeds a certain volume concentration, the slurry will not be fluid, making it difficult to apply the slurry to a uniform wet film thickness. Water is added to improve fluidity. In some cases, a thickener loading is added appropriately to achieve a specific viscosity. On the other hand, adding too much water should be avoided because it can cause several simultaneous problems. One is the waste of energy consumed drying excess water. The second is the increase in the volume concentration of porous pores and channels remaining in the final pad due to water evaporation, which can reduce thermal insulation performance. The third problem is the additional amount of thickener required to maintain the slurry viscosity. That amount of thickener will remain in the final pad and may adversely affect mechanical performance.

[0064] In an embodiment of the present invention, the method for producing the silicone-based fire-resistant sheeting may further include applying a second layer of wet slurry or paste onto the dried layer obtained from step (3) above, followed by further drying. If desired, the method may further include applying a third layer of wet slurry or paste onto the dried second layer. Optionally, the method of the present invention may repeat the applying and drying steps several times.

[0065] In an embodiment of the present invention, the method of producing the silicone-based fire-resistant sheeting may further include removing the dry sheet from a substrate such as a release paper.

[0066] In the present invention, a silicone-based fire-resistant sheet containing 5 to 40% by weight of aerogel particles, hollow particles, or mesoporous particles and 57.5% by weight or more of a polymer binder, which may be silicone alone or a mixture of silicone and an organic polymer, can be used in a secondary battery pack including at least one battery module casing, in which the casing contains multiple battery cells electrically connected to each other. The battery cells are preferably prismatic or pouch-shaped, and are preferably protected by the silicone-based fire-resistant sheet.

[0067] In an embodiment of the present invention, a battery packaging structure is described in which the silicone-based fire-resistant sheet is completely or partially placed in the space between at least two adjacent individual battery cells. When preparing the battery packaging structure, the silicone-based fire-resistant sheet can be cured by removing water before being placed in the space between at least two adjacent individual battery cells. In this method of producing a battery packaging structure, a "cured" or "semi-cured" silicone-based fire-resistant sheet can be completely or partially placed (including inserted) in the space between at least two adjacent individual battery cells to prevent heat transfer from the hot surface of a "burning" cell to adjacent good cells caused by thermal runaway propagation.

[0068] Alternatively, a silicone-based fire-resistant sheet can be placed in the space between at least two adjacent individual battery cells through a curing reaction by removing water from the curable silicone-based composition in the space. In this embodiment of the present invention, a battery package structure is prepared using a curable silicone-based composition that can be cured to become the silicone-based fire-resistant sheet. More specifically, the method for producing this battery package structure includes the following steps: Step (BI): completely or partially filling the space between at least two adjacent individual battery cells with the aqueous curable silicone-based composition as a wet slurry layer; and Step (B-II): subsequent to Step (BI), forming a silicone-based fire-resistant sheet in the space between at least two adjacent individual battery cells by removing water from the applied aqueous curable silicone-based composition at a temperature of up to 140°C.

[0069] Considering the procedural requirements in the battery assembly process or the fire protection performance required for the battery package structure, any of the production methods can be used to place a silicone-based fire protection sheet in the space between at least two adjacent individual battery cells.

[0070] The silicone-based fire-resistant sheet partially or completely fills the open space of the battery module casing, and / or partially or completely covers the battery cells, and / or partially or completely covers the module casing, and optionally covers the lid that covers the battery module casing. The silicone-based fire-resistant sheet is obtained by dispersing a heat-insulating filler in a polymer binder emulsion, applying it to a specific wet thickness, and forming a final sheet containing the heat-insulating inorganic filler after drying the water. The heat-insulating inorganic filler has a mesoporous or hollow structure and a true density of less than 0.25 g / cc. The silicone-based fire-resistant sheet can also be assembled between a water-cooling plate and a metal plate of a battery case to prevent heat diffusion between the water-cooling plate and the metal plate of the battery case. The silicone-based fire-resistant sheet is obtained by dispersing a heat-insulating filler in a polymer binder emulsion, applying it to a specific wet thickness, and forming a final sheet containing the heat-insulating inorganic filler after drying the water. The insulating inorganic filler has a mesoporous or hollow structure and a true density of less than 0.25 g / cc. It can be pre-fabricated and then assembled into a battery case. Alternatively, it can be prepared by dispersing the insulating filler in a polymer binder emulsion to obtain a slurry, which is then applied to the inner surface of the metal plate of the battery case, and then drying the water to form an insulating coating layer sheet. [Example]

[0071] Some embodiments of the present invention are now described in the following examples, in which all parts and percentages are by weight unless otherwise specified.

[0072] Information on the raw materials used in the examples is listed in Table 1 below.

[0073] [Table 1]

[0074] Examples 1 to 5 (IE1 to 5) of the present invention and Comparative Examples 1 to 3 (CE1 to 3) In Examples 1-5 of the present disclosure, silicone-based fireproof sheets were made using the raw materials and their amounts set forth in Table 2. Comparative Examples 1-3 served as controls.

[0075] [Table 2]

[0076] For IE1-4 and CE1-3, three steps were involved: Step 1: Formulate the wet slurry; Step 2: Applying the wet slurry onto a substrate and removing the water to provide a dry sheet; Step 3: Test the thermal insulation performance of the dryer sheet at high temperatures.

[0077] A detailed description of the steps is provided below: Step 1: Formulate the wet slurry Dowsil 8005, DI water (if needed), FR-122P (if needed), and Sb2O3 (if needed) were added to a 1-liter plastic cup and mixed with a Cowles blade at a stirring speed of 300 rpm to form a homogeneous slurry. Keltrol CG powder was then slowly added while stirring at 300 rpm to ensure powder dissolution and to avoid clumping of the Keltrol CG powder. After complete dissolution and viscosity increase, IC3110 or S-15 (if needed) was gradually added while stirring at 300 rpm to create a homogeneous slurry.

[0078] Step 2: Apply the wet slurry onto a substrate and remove the water to provide a dry sheet The slurry obtained in step 1 was spread on a PTFE sheet using a knife doctor to form a wet sheet having a thickness of 2.5 mm, which was then dried in an oven at 90°C for 1 hour to obtain a dry sheet.

[0079] Step 3: The sheet's insulating performance at high temperatures.

[0080] The dried sheet was cut into an 8 cm x 8 cm square and placed on a heat stage stabilized at 630 °C. An Al plate with two 0.5 mm OD K-type thermocouples was attached to the backside of the specimen, partially embedded in a 0.4 mm groove, in close contact with the specimen's backside to record the backside temperature. To control heat diffusion, the entire surface of the Al plate was thoroughly covered with insulating asbestos board. A steel load was then placed on the Al plate, applying a pressure of 0.03 MPa to the specimen. See Figure 1 for a description of the setup. The entire setup was completed within 10 seconds after the specimen was attached to the heat stage. The 630 °C heat stage temperature was calibrated by placing a square 8 cm x 8 cm aerogel sheet / pad with a thickness of 4 ± 0.2 mm on the Al plate, with one thermocouple directly contacting the heat stage surface at the center of the sheet. Calibration continued for at least 20 minutes with the 630 °C heat stage surface stabilized before starting the thermal insulation performance test. During the test, the backside temperature was recorded from the time the specimen was attached to the heat stage. The test lasted for 20 minutes. The original thickness of the sheet specimen was measured at each corner, and the average thickness was calculated. During the test, a feeler gauge was inserted between the heat stage and the Al plate, and the thickness was measured just before the end of the test. Both the change in backside temperature and the change in thickness over the test period were recorded.

[0081] For IE5, we still included the three steps above, but split step 2 into two parts: 2-1: The wet slurry is applied onto a substrate and the water is removed to obtain a dry loose sheet; 2-2: Dowsil 8005 (i.e., polymer emulsion) is impregnated into the dried loose sheet, and the water is removed to obtain the final sheet.

[0082] Details of Step 2-1 and Step 2-2 are as follows: Step 2-1: A slurry of Syntegra YS-3000, water, Keltrol CG thickener, antifoaming agent 4-88, and aerogel filler IC3110 was spread onto a PTFE sheet using a knife doctor to form a wet sheet 2.5 mm thick. The wet sheet was dried in an oven at 90°C for 1 hour to obtain a dry loose sheet.

[0083] Step 2-2: The loose sheet was uniformly impregnated with Dowsil 8005 using a brush, and the impregnated loose sheet was placed in an oven at 90°C for 1 hour to obtain a dry sheet.

[0084] [Table 3]

[0085] The total binder weight percent in the dry sheet is important for mechanical strength. CE3 showed unacceptable dry sheet strength and was easily crushed to powder with the fingers because the binder loading in CE3 was less than 60%. IE3 showed marginal sheet strength at 60.2 weight percent binder, suggesting that more than 60 weight percent binder in the dry sheet was required to ensure sufficient sheet strength for downstream assembly operations in battery module and package production.

[0086] Compared with CE1 (i.e., a silicone sheet containing no insulating filler), IE1-5 exhibit much lower backside temperatures (see Figures 2-4), suggesting a significant improvement in thermal insulation performance. To meet the practical design criteria, a lower backside temperature of less than 220°C, preferably less than 170°C, was required for a 2.5 mm thick insulating sheet when placed on a heat stage at 630°C for 20 minutes under a pressure of 0.03 MPa. All examples of the present invention meet the practical design criteria. The amount of insulating filler in IE1 is close to the lower limit, suggesting that an insulating filler content of >15 wt% is preferred to maintain good thermal protection performance.

[0087] The weight percent of polysiloxane in the binder is important for thermal insulation performance. CE2 showed that when polyurethane was used as the main binder, the thermal insulation performance was even worse than CE1, i.e., a silicone sheet containing no insulating filler. IE5 showed that the thermal insulation performance was good when polysiloxane was the majority of the binder. It was suggested that the weight percent of polysiloxane in the binder should be >50%, preferably >60%, and more preferably >70%.

[0088] All examples except IE4 did not experience any ignition during the test due to the addition of flame retardant additives to the sheet. IE4 did experience a small ignition, but it quickly extinguished when removed from the heat stage at the end of the test. Small ignitions can generally be eliminated by adding some flame retardant additives.

[0089] Testing and Evaluation The acceptance criteria included three parts: mechanical strength, thermal insulation at high temperatures, and flame ignition in a heat stage test.

[0090] mechanical strength The mechanical strength of the insulation sheet is evaluated by bending. If a sheet with a thickness of 2.5 mm can be bent from one end to the other with a radius of 1 cm more than 50 times without any change or damage, it is scored as "very good." If it can be bent more than 10 times without obvious damage, it is scored as "good." If it can be bent more than once without obvious damage, it is scored as "marginal." If it cannot be bent, it is scored as "unacceptable." Since the sheet is wound in mass production, it is necessary to bend it at least once. The mechanical strength of the sheet in CE3 and IE3 suggested that a binder load of >60% by mass was required.

[0091] High temperature insulation High-temperature insulation performance is evaluated by a heat stage test. In practical design, a 2.5 mm thick insulation sheet requires a backside temperature of less than 220°C when placed on a heat stage at 630°C for 20 minutes under a pressure of 0.03 MPa. All inventive examples meet the criteria. IE1 is near the lower limit, suggesting that >15% by weight of insulating filler is preferred to maintain good thermal protection performance. On the other hand, CE1 and IE5 indicate that the weight percent of polysiloxane in the binder must be in the majority to ensure sufficient insulation performance. The weight percent of polysiloxane in the binder must be >50%, preferably >60%, and more preferably >70%.

[0092] Flame ignition in heat stage testing Flame ignition of insulation sheets is assessed by the appearance of fire during the test. If the sheet ignites, additional heat will likely be generated, which must be avoided. IE1 to IE3 indicate that flame ignition can be avoided by adding a flame retardant additive.

Claims

1. A silicone-based fireproof sheet having a structure in which at least one heat insulating filler selected from aerogel particles, hollow particles, and mesoporous particles is bound to a silicone-based polymer binder, wherein the amount of the heat insulating filler is 5 to 40 mass % and the amount of the silicone-based polymer binder is 57.5 to 95 mass % when the total mass of the solid content of the silicone-based fireproof sheet is 100 mass %.

2. 2. The silicone-based fire-resistant sheet according to claim 1, wherein the average size of the heat-insulating filler is 1 μm to 1.20 mm, and at least 50% by weight of the silicone-based polymer binder is cured silicone.

3. 2. The silicone-based fire-resistant sheet according to claim 1, wherein the aerogel particles have an average size in the range of 0.01 to 1.0 mm and an amount of the aerogel particles in the silicone-based fire-resistant sheet in the range of 15 to 35% by mass, where the total mass of the solid content of the silicone-based fire-resistant sheet is 100% by mass.

4. 2. The silicone-based fire-resistant sheet according to claim 1, wherein the silicone-based polymer binder is a water-based silicone polymer binder.

5. 2. The silicone-based fire-resistant sheet according to claim 1, wherein the silicone-based polymer binder comprises a water-based silicone polymer binder containing colloidal silica.

6. 2. The silicone-based fire-resistant sheet according to claim 1, wherein the silicone-based polymer binder further comprises at least one selected from the group consisting of a flame retardant additive, a curing catalyst, a rheology modifier, an antifoaming additive, a wetting additive, a surface treatment agent, a colorant, a filler other than the heat-insulating filler, an antioxidant additive, a biocide, an ultraviolet (UV) stabilizing additive, and an adhesion-promoting additive.

7. The silicone fire-resistant sheet according to any one of claims 1 to 6, which is applied to a battery package.

8. A battery packaging structure, wherein the silicone-based fire-resistant sheet according to any one of claims 1 to 6 is disposed completely or partially within the space between at least two adjacent individual battery cells.

9. The battery packaging structure according to claim 8 , wherein the shape of the battery is a prismatic shape or a pouch shape.

10. 9. The battery packaging structure of claim 8, wherein the silicone-based fire-resistant sheet is a silicone-based sheet that is cured before being placed in the space between at least two adjacent individual battery cells.

11. 9. The battery packaging structure according to claim 8, wherein the silicone-based fire-resistant sheet is a cured silicone-based product through a curing reaction of a curable silicone-based composition in the space between at least two adjacent individual battery cells.

12. An aqueous curable silicone composition that is formed into the silicone fire-resistant sheet according to any one of claims 1 to 7 through a curing reaction, comprising: (A) a silicone-based polymeric binder containing at least 50% by weight of a curable silicone polymer in an amount ranging from 57.5 to 95% by weight; (B) at least one insulating filler selected from aerogel particles, hollow particles, and mesoporous particles in an amount ranging from 5 to 40% by weight; (C) a curing agent; (D) water, and optionally (E) at least one selected from the group consisting of a flame retardant additive, a curing catalyst, a rheology modifier, an antifoaming additive, a wetting additive, a surface treatment agent, a colorant, a filler other than the heat insulating filler, an antioxidant additive, a biocide, an ultraviolet (UV) stabilizing additive, and an adhesion promoting additive; Including, This is an aqueous curable silicone composition when the total mass of the solid content of the silicone fireproof sheet is taken as 100 mass %.

13. 13. The aqueous curable silicone composition of claim 12, wherein component (A) is a silicone-based polymeric binder containing a curable silicone polymer and other curable / polymerizable materials, the other curable / polymerizable materials being in an amount of 0% to 30% by weight.

14. 13. The aqueous curable silicone composition of claim 12, wherein component (A) is emulsified or uniformly dispersed in (D) water.

15. A method for producing the silicone fireproof sheet according to any one of claims 1 to 7, comprising the following steps: Step (I): applying the aqueous curable silicone-based composition according to any one of claims 11 to 13 as a wet slurry layer onto a substrate optionally having a release layer; Step (II): Following step (I), forming the silicone-based fire-resistant sheet by removing water from the applied aqueous curable silicone-based composition at a temperature of up to 140°C.

16. 16. The method for producing a silicone-based fire-resistant sheet according to claim 15, wherein in step (I), the thickness of the wet slurry layer of the aqueous curable silicone-based composition is 0.2 to 10.0 mm.

17. 16. The method for producing a silicone-based fire-resistant sheet according to claim 15, further comprising the step of controlling the viscosity and / or flowability of the aqueous curable silicone-based composition by adding water and / or a rheology modifier prior to or at the same time as step (I).

18. 9. A method for producing a battery packaging structure according to claim 8, comprising the step of disposing the silicone-based fire-blocking sheet according to any one of claims 1 to 7 completely or partially in a space between at least two adjacent individual battery cells.

19. Steps below: Step (BI): completely or partially filling the space between at least two adjacent individual battery cells with the aqueous curable silicone-based composition of any one of claims 12 to 14 as a wet slurry layer; Step (B-II): Following step (B-I), forming a silicone-based fireproof sheet in the space between at least two adjacent individual battery cells by removing water from the applied aqueous curable silicone-based composition at a temperature of up to 140°C; 10. A method for producing the battery package structure of claim 8, comprising:

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