Flame retardant composition, method of making the same, and battery comprising the same

Abstract

A battery module includes a plurality of secondary battery cells arranged side by side; and a flame retardant composition provided on top of the plurality of secondary battery cells; wherein the flame retardant composition includes a first composition and a second composition. The first composition includes a porous particle on which a first metal catalyst particle and a first flame retardant particle are provided. The second composition includes a fiber composition including a fiber base material on which a second metal catalyst particle and a second flame retardant particle are provided.

Description

Technical Field

[0001] This disclosure relates to flame retardant compositions for energy storage devices, methods of manufacturing the same, and articles comprising the same. Specifically, this disclosure relates to flame retardant compositions for batteries, methods of manufacturing the same, and battery modules and battery packs comprising the flame retardant compositions. Background Technology

[0002] Batteries, comprising multiple assembled battery cells (such as secondary batteries), are used in a variety of applications, including portable electronic devices, e-bikes, hybrid vehicles, and electric vehicles. Because secondary battery cells store electrical energy at high density, they often generate unusually high amounts of heat and gas, which can lead to undesirable thermal events. This phenomenon frequently occurs when the battery is accidentally short-circuited or damaged.

[0003] Furthermore, when one battery cell in an assembled battery module experiences an adverse thermal event, it may trigger a corresponding adverse event in an adjacent secondary battery cell. It is desirable to prevent such adverse events from occurring sequentially.

[0004] We also hope to provide flame retardant materials that can be used in energy storage devices such as batteries, capacitors, and supercapacitors, which can increase the flame retardancy of energy storage devices. Summary of the Invention

[0005] A flame retardant composition for a battery module includes a first composition and a second composition disposed on top of a plurality of battery cells in the battery module. The first composition comprises porous particles on which first metal catalyst particles and first flame retardant particles are disposed. The second composition comprises a fibrous composition on which second metal catalyst particles and second flame retardant particles are disposed.

[0006] On the one hand, the first composition and the second composition are tightly mixed and added to the battery module as a single layer.

[0007] On the other hand, the first composition is disposed in the first layer, and the second composition is disposed in the second layer; wherein the second layer is farther away from the secondary battery cell than the first layer.

[0008] On the other hand, a first layer containing the first composition is disposed between two second layers, each second layer containing the second composition.

[0009] On the other hand, a second layer containing the second composition is disposed between the two first layers containing the first composition.

[0010] On the other hand, the first metal catalyst particle has the same chemical composition as the second metal catalyst particle.

[0011] On the other hand, the first metal catalyst particles have a different chemical composition than the second metal catalyst particles.

[0012] On the other hand, the first flame retardant particles have the same chemical composition as the second flame retardant particles.

[0013] On the other hand, the first metal catalyst particle and the second metal catalyst particle each contain a transition metal.

[0014] On the other hand, the first metal catalyst particle and the second metal catalyst particle are independently selected from iron, nickel, cobalt, platinum, palladium, rhodium, tungsten, titanium, niobium, hafnium, vanadium, molybdenum, manganese or combinations thereof.

[0015] On the other hand, the first flame retardant particles and the second flame retardant particles are independently selected from metal hydroxides, metal halides, phosphorus-containing flame retardants, nitrogen-containing flame retardants, and combinations thereof.

[0016] On the other hand, phosphorus-containing flame retardants are organophosphates, among which nitrogen-containing flame retardants are melamine.

[0017] On the other hand, the porous particles are selected from zeolites, aerogels, metal-organic frameworks, pyrolytic metal oxides or combinations thereof.

[0018] A battery module includes a plurality of secondary battery cells arranged side by side; and a flame retardant composition disposed on top of the plurality of secondary battery cells; wherein the flame retardant composition comprises a first composition and a second composition. The first composition comprises porous particles on which first metal catalyst particles and first flame retardant particles are disposed. The second composition comprises a fiber composition comprising a fiber substrate on which second metal catalyst particles and second flame retardant particles are disposed.

[0019] On the one hand, the first metal catalyst particle has the same chemical composition as the second metal catalyst particle.

[0020] On the other hand, the first metal catalyst particles have a different chemical composition than the second metal catalyst particles.

[0021] On the other hand, the first flame retardant particles have the same chemical composition as the second flame retardant particles.

[0022] On the other hand, the first metal catalyst particles and the second metal catalyst particles contain transition metal particles.

[0023] On the other hand, metal catalyst particles, flame retardant particles, and porous particles are mixed with polymer binders to create a slurry that fills all the free spaces in the module.

[0024] The above-described features and advantages, as well as other features and advantages, of this disclosure will become apparent from the following detailed description when taken in conjunction with the accompanying drawings. Attached Figure Description

[0025] Other features, advantages, and details appear only by way of example in the following detailed description, which refers to the accompanying drawings, wherein:

[0026] Figure 1 This is an exemplary schematic diagram of a cross-section of a battery module including multiple secondary battery cells; and

[0027] Figure 2 This is an exemplary schematic diagram of a battery module having a flame retardant composition disposed on top of a secondary battery cell. Detailed Implementation

[0028] The following description is exemplary in nature and is not intended to limit this disclosure, its application or use.

[0029] This document discloses a flame retardant composition disposed in a battery module to increase the overall flame retardancy of the module and minimize adverse thermal events, such as thermal runaway. The flame retardant composition is disposed in the battery module and located on top of a plurality of battery cells contained within the battery module. In one embodiment, the flame retardant composition is disposed in the battery module and located on top of a plurality of vertically aligned battery cells contained within the battery module.

[0030] The flame retardant composition comprises a fibrous substrate in which a slurry comprising a porous medium, metal catalyst particles, and flame retardant particles is disposed. The slurry may optionally contain a polymer binder. The slurry can be cast into a module to fill empty spaces within the module. In another embodiment, the flame retardant composition comprises a fibrous substrate in which a slurry comprising a porous medium, metal catalyst particles, and flame retardant particles is permeated. In one embodiment, the flame retardant composition may be applied as a single layer to a battery module on top of a plurality of vertically aligned battery cells.

[0031] In another embodiment, the flame retardant composition may be used in two or more layers in the battery module—a first layer comprising a first composition containing a particulate flame retardant composition, and a second layer comprising a second composition containing a fibrous flame retardant composition. The first composition of the first layer is a particulate composition comprising a porous medium, first metal catalyst particles, and first flame retardant particles, while the second composition of the second layer is a fibrous composition comprising a fibrous substrate, second metal catalyst particles, and second flame retardant particles. The first metal catalyst particles may be the same as or different from the second metal catalyst particles, and the first flame retardant particles may be the same as or different from the second flame retardant particles. In a preferred embodiment, the first metal catalyst particles are the same as the second metal catalyst particles, and the first flame retardant particles are the same as the second flame retardant particles. The first and second layers may be placed in the battery module in different configurations discussed herein.

[0032] In another embodiment, the first and second compositions may be mixed together into a tight mixture and applied as a monolayer to the battery module detailed herein.

[0033] Figure 1 This is an exemplary schematic cross-section of a battery module 100, which includes multiple modules 150, 250, etc., arranged parallel to each other. Each module includes multiple battery cells. For example, a first module 150 includes battery cells 102, 104, 106, etc., while a second module 250 includes battery cells 102', 104', 106', etc. The first module 150 is separated from the second module 250 by a barrier 200. The multiple battery cells 102, 104, 106… are housed in a protective casing 108. At the top of the battery cells 102, 104, 106, etc. is a space 210, into which a flame retardant composition may be applied as a single layer or in multiple layers.

[0034] Flame retardant compositions used in single-layer applications

[0035] As described above, the flame retardant composition (when used as a single layer) comprises a fibrous substrate into which a slurry comprising a solvent, a porous medium, metal catalyst particles and flame retardant particles permeates.

[0036] The fiber substrate comprises an inherently non-flammable fiber composition. The fibers in the fiber composition preferably have an aspect ratio greater than 1, more preferably greater than 5, and more preferably greater than 10. As used herein, "fiber" includes fibers that can exist in the form of whiskers, needles, rods, tubes, wires, elongated lamellar crystals, thin sheet-like lamellar crystals, ellipsoids, microfibers, nanofibers and nanotubes, elongated fullerenes, etc. When this filler exists in aggregate form, aggregates with an aspect ratio greater than 1 are also sufficient.

[0037] Non-limiting examples of suitable fiber fillers include short inorganic fibers, including processed mineral fibers, such as those derived from mixtures containing at least one of aluminosilicate, alumina, magnesium oxide, and calcium sulfate hemihydrate; boron fibers; ceramic fibers such as silicon carbide; and fibers produced by 3M Corporation of St. Paul, Minnesota, USA, under the trademark name... The company sells fibers made of mixed oxides of aluminum, boron, and silicon. The fiber substrate may also include monocrystalline fibers or "whiskers," including silicon carbide, alumina, boron carbide, iron, nickel, and copper. It may also include fiber substrates such as glass fiber, basalt fiber, including textile glass fiber, and quartz.

[0038] This reinforcing filler can be provided in the form of monofilament or multifilament fibers and can be used alone or in combination with other types of fibers, such as through co-weaving or core / skin, side-by-side, orange-type, or matrix and fibrillary structures, or through other methods known to those skilled in the art of fiber manufacturing. Typical co-weaving structures include glass fiber-carbon fiber, carbon fiber-aramid (aramid) fiber, and aramid fiber-glass fiber. The glass-containing fiber substrate can be provided, for example, in the form of rovings, woven fiber reinforcements such as 0-90 degree fabrics, nonwoven fiber reinforcements such as continuous fiber mats, chopped strand mats, tissue paper, paper and felt, as well as three-dimensional woven reinforcements, preforms, and braids.

[0039] In a preferred embodiment, glass fibers are used as the fiber substrate. Useful glass fibers can be formed from any type of fiberizable glass composition, including those prepared from fiberizable glass compositions, commonly referred to as "E glass," "A glass," "C glass," "D glass," "R glass," "S glass," and fluorine-free and / or boron-free E glass derivatives. Most reinforcing mats comprise glass fibers formed from E glass.

[0040] Commercially produced glass fibers typically having a nominal filament diameter of about 4.0 to about 35.0 micrometers, and most commonly produced E-glass fibers having a nominal filament diameter of about 9.0 to about 30.0 micrometers, can be used in fiber-based substrates.

[0041] The filaments of the fiber-based matrix are produced by standard processes (e.g., by steam or air blowing, flame blowing, and mechanical stretching). Preferred filaments for the fiber-based matrix can be produced by mechanical stretching. The glass fibers may or may not be sized. Sizing glass fibers have at least a portion of their surface coated with a sizing composition that facilitates the wetting and penetration of any matrix material placed on the fiber bundle and contributes to achieving the desired physical properties in the composite material.

[0042] Glass fibers are preferably sized bundles of glass. In preparing glass fibers, many filaments can be formed simultaneously, sized with a coating agent, and then bundled together. Alternatively, the bundle itself can be formed first from filaments and then sized. The amount of sizing used is typically sufficient to bond the glass filaments into a continuous bundle and ranges from about 0.1 to about 5% by weight, more typically from about 0.1 to 2% by weight, based on the weight of the glass fibers. Typically, this can be about 1.0% by weight based on the weight of the glass filaments. Short bundles of glass fibers, about 1 / 4 inch long or shorter, preferably about 1 / 8 inch long, can also be used. If desired, their length can also be greater than about a quarter inch.

[0043] In a preferred embodiment, the fiber composition comprises glass fibers in the form of fibrous glass. Generally, the glass fibers are present in the flame retardant composition in an amount up to about 50% by weight based on the total weight of the composition, preferably about 1% to about 20% by weight based on the total weight of the flame retardant composition.

[0044] Carbon fiber can also be used as a fiber matrix in flame retardant compositions. Carbon fiber has several advantages, including high stiffness, high tensile strength, low weight-to-strength ratio, high chemical resistance, high temperature resistance, and low thermal expansion. The precursors for carbon fiber are polyacrylonitrile (PAN), rayon, and pitch. These precursors are first woven into filament yarns, and then stretched under tension at temperatures exceeding 1000°C, preferably exceeding 1500°C, to form carbon fiber.

[0045] Carbon fibers can also be treated with the sizing agents detailed above. Fiber substrates containing carbon fibers can also be provided in the form of, for example, rovings, woven fiber reinforcements such as 0-90 degree fabrics, nonwoven fiber reinforcements such as continuous fiber mats, chopped strand mats, tissues, paper and mats, as well as three-dimensional woven reinforcements, preforms, and braids.

[0046] The amount of glass fiber in the flame retardant composition is up to about 50% by weight based on the total weight of the composition, preferably about 1 to about 20% by weight based on the total weight of the flame retardant composition.

[0047] Porous media

[0048] The flame retardant composition comprises a porous medium (hereinafter referred to as porous particles), which may be added to the composition alone or alternatively together with a first flame retardant and a first metal catalyst disposed on the porous medium (hereinafter referred to as first metal catalyst particles). The porous particles can react with most of the gases, such as hydrogen and hydrocarbon gases, initially generated in the battery during adverse thermal events to terminate the combustion chain branching reaction and inhibit the spread of adverse thermal events.

[0049] Furthermore, the high specific surface area of ​​porous particles can adsorb combustible gases. In one embodiment, the first metal catalyst particles can convert gases released during thermal escape to produce carbon-containing particles, thereby solidifying hydrocarbon gases. Porous media (e.g., zeolite) also catalyze char formation. The char undergoes expansion due to the synergistic reaction between the zeolite, polymer components such as any binders used, and flame-retardant chemicals such as ammonium phosphate. This expansion increases flame retardancy.

[0050] Expansion is the act or process of growing larger or expanding, which consumes some of the heat generated during adverse thermal events, thereby mitigating the spread of these events. The particulate nature of porous media allows them to fill spaces and gaps within the module, providing close contact with the battery cells. This close contact can help to rapidly eliminate adverse thermal events within the module. Suitable examples of porous particles are zeolites, aerogels, pyrolytic metal oxides, metal-organic frameworks (MoF), and combinations thereof.

[0051] zeolite

[0052] Zeolites are a form of molecular sieve, consisting of microporous crystalline solids with a well-defined structure containing silicon, aluminum, and oxygen in their framework, and may also contain cations within their pores. Zeolites (similar to all the porous media detailed herein) can be added alone to flame retardant compositions (without metal catalyst particles or flame retardant particles), or they can be added to flame retardants together with a portion of metal catalyst particles and a portion of flame retardant particles (from the flame retardant composition).

[0053] Zeolites possess an interconnected alumina and silica crystalline framework, particularly a cross-linked alumina and silica crystalline framework via shared oxygen atoms, and can therefore be characterized by the silica-alumina ratio (SAR). Generally, as the SAR of a zeolite increases, the zeolite exhibits increased hydrothermal stability. Molecular sieves are defined by their crystalline or pseudocrystalline structure, which is formed by molecular tetrahedral units interconnected in a regular and / or repeating manner to form a framework.

[0054] Zeolites possess a three-dimensional molecular framework derived from the orientation of their interconnecting pores. The pores of these molecular sieves typically have volumes on the order of several cubic nanometers and openings (also called “pores” or “pore openings”) on the order of several angstroms in diameter. These pores are defined by the ring size of their pores, where, for example, the term “8-ring” refers to a closed ring consisting of eight tetrahedral coordinated silicon (or aluminum) atoms and eight oxygen atoms. In some zeolites, the channels are aligned within the framework to form one or more channels that penetrate the framework, thus creating a mechanism that restricts the entry or passage of different molecular or ion species based on the relative size of the channels and the molecular or ion species.

[0055] This feature is useful because the size of the zeolite (used as a substrate) allows some combustible gases generated during thermal events to enter its pores (and be deprived of oxygen), while some other gases (potentially non-combustible) are excluded from the porous substrate. This feature minimizes the continuous propagation of thermal events from one cell to an adjacent cell, thereby improving flame retardancy. The size and shape of the zeolite pores therefore affect its catalytic activity, as they exert a spatial influence on the reactants, controlling the entry of reactants and products.

[0056] Molecular sieves with small-pore frameworks (i.e., containing a maximum ring size of 8) have been found to be particularly useful in SCR applications. Small-pore molecular sieves include those with the following crystal structure types: CHA, LEV, ERI, and AEI. Specific examples of aluminosilicates and aluminosilicate phosphates of molecular sieves with a CHA framework include SAPO-34, AIPO-34, and SSZ-13.

[0057] aerogel

[0058] Aerogels can also be used as porous particles, which can be used alone (as defined above - without metal catalyst particles or without flame retardant particles) or alternatively with some or all of the catalyst metal particles and flame retardant particles placed thereon. Aerogels are synthetic porous ultralight materials derived from wet gels, in which the liquid component of the wet gel is replaced by gas, and the gel structure does not collapse significantly. The result is a solid with extremely low density and extremely low thermal conductivity. Aerogels are good thermal insulators because they virtually eliminate two of the three modes of heat transfer—conduction (they are primarily composed of insulating gases) and convection (the microstructure prevents net gas movement). They are good conductive thermal insulators because they are almost entirely composed of gas, which is a very poor thermal conductor. They are good convection inhibitors because air cannot circulate within the lattice.

[0059] Inorganic and organic aerogels can also be used as porous particles. Inorganic aerogels include silica aerogel, alumina aerogel, nickel-alumina aerogel, holmium oxide aerogel, iron oxide aerogel, erbium oxide aerogel, chromium oxide aerogel, samarium oxide aerogel, vanadium oxide aerogel, neodymium oxide aerogel, or combinations thereof. Aerogels can be surface-treated with surface treatment agents such as hexamethyldisilazane and trichloromethylsilane to prevent moisture from entering the porous particles.

[0060] Organic aerogel particles can include particles obtained from biopolymers as well as particles obtained from synthetic organic polymers.

[0061] Examples of biopolymers that can be used in aerogels include cellulose, cellulose with reduced crystallinity, polysaccharides, deacetylated chitosan, oligo-deacetylated chitosan, gelatin, collagen, hydroxyalkyl cellulose such as hydroxypropyl cellulose, hydroxymethyl cellulose, and hydroxyethyl cellulose; sodium carboxymethyl cellulose, cellulose acetate, cellulose diacetate, cellulose triacetate, cellulose propionate, cellulose acetate butyrate, and cellulose ethers such as ethyl cellulose, sugars (glucose, sucrose, lactose, galactose, fructose, mannitol, sorbitol, or combinations thereof), proteins, starch, pectin, alginate, sodium octenyl succinate starch, locust bean gum, carrageenan, agar, xanthan gum, guar gum, casein, whey protein isolate, soybean protein isolate, pea protein isolate, potato protein isolate, corn protein, lecithin, stearic acid, beeswax, cottonseed wax, carnauba wax, milk fat, palm kernel oil, etc., or combinations thereof.

[0062] Synthetic polymers can also be used in aerogels. The synthetic polymer is an organic polymer, selectable from various thermoplastic polymers, mixtures of thermoplastic polymers, thermosetting polymers, or mixtures of thermoplastic and thermosetting polymers. The organic polymer can also be a polymer, copolymer, terpolymer, or mixture thereof containing at least one of the aforementioned organic polymers. The organic polymer can also be an oligomer, homopolymer, copolymer, block copolymer, alternating block copolymer, random polymer, random copolymer, random block copolymer, graft copolymer, star-shaped block copolymer, dendritic polymer, polyelectrolyte (a polymer having repeating groups containing electrolytes), polyampholyte (a polyelectrolyte having repeating cationic and anionic groups), ionomer, etc., or combinations thereof. The number average molecular weight of the organic polymer is greater than 10,000 g / mol, preferably greater than 20,000 g / mol, more preferably greater than 50,000 g / mol.

[0063] Examples of thermoplastic polymers that can be used in polymeric materials include polyacetal, polyacrylic acid, polycarbonate, polyalkyd resin, polystyrene, polyolefin, polyester, polyamide, polyarylamide, polyamide-imide, polyarylide, polyurethane, epoxy resin, phenolic resin, silicone resin, polyarylsulfone, polyethersulfone, polyphenylene sulfide, polysulfone, polyimide, polyetherimide, polytetrafluoroethylene, polyetherketone, polyetheretherketone, polyetherketoneketone, polybenzoxazole, polyoxadiazole, polybenzothiazide-benzothiazide, polybenzothiazide, polypyrazine-quinoxaline, polypyrroleimide, polyquinoxaline, and polybenzimidazole. Zyrazole, polyindoline, polyoxyisoindoline, polydioxyisoindoline, polytriazine, polypyridazine, polypiperazine, polypyridine, polypiperidine, polytriazole, polypyrazole, polycarboborane, polyoxabicyclononane, polydibenzofuran, polyphthalamide, polyacetal, polyanhydride, polyethylene ether, polyethylene sulfide, polyvinyl alcohol, polyvinyl ketone, polyhalogenated ethylene, polyvinyl acrylonitrile, polyethylene ester, polysulfonate, polysulfide, polysulfide, polysulfone, polysulfonamide, polyurea, polyphosphazene, polysilazane, polypropylene, polyethylene, polyethylene terephthalate, polyvinylidene fluoride, polysiloxane, etc., or combinations thereof.

[0064] Examples of thermosetting polymers include epoxy polymers, unsaturated polyester polymers, polyimide polymers, bismaleimide polymers, bismaleimide triazine polymers, cyanate ester polymers, vinyl polymers, benzoxazine polymers, benzocyclobutene polymers, acrylic resins, alkyd resins, phenolic resins, methyl phenolic resins, melamine-formaldehyde polymers, urea-formaldehyde polymers, hydroxymethyl furan, isocyanates, diallyl phthalate, triallyl cyanurate, triallyl isocyanurate, unsaturated polyesterimides, resorcinol formaldehyde, phenol formaldehyde, melamine formaldehyde, cresol formaldehyde, phenol furfuryl alcohol, etc., or combinations thereof. Biopolymer aerogels are preferred. Among biopolymers, alginate-based aerogels are preferred.

[0065] Aerogels can be manufactured using supercritical extraction, freeze drying, or a combination thereof.

[0066] Pyrolytic metal oxides

[0067] Pyrolytic metal oxides in the form of porous aggregates of nanoparticles are effective as thermally conductive solid components and can be used as porous particles in the first composition of flame retardant compositions. Examples of pyrolytic metal oxides are pyrolytic silica, pyrolytic alumina, pyrolytic zirconium oxide, pyrolytic titanium dioxide, or combinations thereof.

[0068] Based on the total volume of the porous substrate before impregnation with the transition metal precursor (described in detail below) and the flame retardant compound (described in detail below), the porous particles have a high surface area and a porosity of more than 50% by volume, preferably more than 70% by volume, and more preferably more than 90% by volume.

[0069] The average pore size in the porous particles can be from 5 angstroms to 100 micrometers (μm), preferably from 100 nanometers (nm) to 50 micrometers, and more preferably from 150 nanometers to 20 micrometers. It is desirable for the porous substrate to contain a higher volume percentage of micrometer-sized pores compared to the volume percentage of nanometer-sized pores. This prevents the porous substrate from collapsing due to capillary pressure when exposed to liquids (e.g., moisture, battery acids, etc.).

[0070] Porous particles can have a unimodal, bimodal, or multimodal particle size distribution. A multimodal particle size distribution is preferred because it allows for better packing of the particles in the first composition. Porous particles can have an average particle size of 2 nanometers to 1000 micrometers, preferably 10 nanometers to 100 micrometers, and more preferably 50 to 10 micrometers.

[0071] Metal-organic framework

[0072] Metal-organic frameworks (MOFs) are among the fastest-growing classes of materials in chemistry today. They consist of interchangeable metal nodes and carbon-based pillars. The Cambridge Crystallography Data Centre has recorded over 15,000 MOFs, providing a vast array of materials to choose from.

[0073] MOFs possess specific surface areas and micropore volumes that surpass those of traditional adsorbents such as zeolites and activated carbon. MOFs are hybrid inorganic-organic frameworks assembled from secondary structural units (SBUs) typically composed of metal ions or clusters, linked by rigid organic ligands. Various cations and molecular bridges can be incorporated into the framework to create a variety of materials with different pore sizes and functions.

[0074] To successfully design adsorbents, it is essential to fully understand their structure, including pore size / shape and adsorbate properties. Adsorbates attach to surfaces through weak mutual attraction known as van der Waals forces. Adsorption occurs in pores with diameters approximately twice the molecular diameter of the adsorbed molecule, which is why the pore size distribution within the adsorbent is a decisive factor. Currently available MOFs can adsorb molecules ranging from macropores to mesopores. According to IUPAC nomenclature, micropores are defined as pores with diameters less than 2 nm, and mesopores are defined as pores with diameters between 2 and 50 nm. The pore size is chosen to provide an easy diffusion path for adsorbate molecules to desorb and diffuse out of the pore network.

[0075] Another material property that may affect adsorbate adsorption is the presence of open metal sites, thus affecting the chemistry / functionality of MOFs to some extent.

[0076] In some MOFs, the metal center binds within a specific coordination environment, allowing the central cation to be open and accessible to adsorbed gas molecules. Compared to non-open metals, unsaturated metal sites have been shown to enhance the affinity for certain adsorbates.

[0077] It should be noted that, if necessary, combinations of two or more metal-organic frameworks, zeolites, aerogels, pyrolytic metal oxides, etc., can be used.

[0078] Based on the total weight of the flame retardant composition, porous particles may be added to the flame retardant composition in an amount of 1-20% by weight, preferably 2-15% by weight.

[0079] Metal catalyst particles

[0080] Metal catalyst particles are used in flame retardant compositions and can be added to the flame retardant composition alone (without placing them on porous particles), or alternatively, they can be dispersed on porous particles and then added to the flame retardant composition.

[0081] When the flame retardant composition is added to a battery module in two layers, metal catalyst particles can be added to the first layer with a first composition and to the second layer with a second composition. The metal catalyst particles in the first composition can be the same as or "different" from those in the second composition. The term "different" implies a chemical difference—the chemical properties of the metal particles in the first composition differ from those of the metal particles in the second composition.

[0082] Metal catalyst particles are used to catalyze the release of carbon-containing gases generated in the battery module during thermal runaway. Gases are produced when the battery is heated to undesirable temperatures. These gases are typically carbon-containing (i.e., they contain hydrocarbons, carbon dioxide, carbon monoxide, or combinations thereof) and are released from the electrolyte used in the battery. These gases are flammable and toxic.

[0083] Metal particles can act as catalysts, converting these carbon-containing gases into carbon-containing solids, such as carbon nanotubes, graphene, graphite particles, polyacetylene, or combinations thereof. In other words, they solidify the gas, reducing its adverse effects. Furthermore, some of the formed solids expand (sometimes referred to as exfoliation, especially in the case of graphite), which promotes flame retardancy and helps suppress or delay adverse thermal events. It should be noted that some of these carbon-containing gases enter the pores of the porous particles, where they are isolated and combustion is prevented due to oxygen deficiency.

[0084] Suitable metal particles include transition metal particles, such as iron, nickel, cobalt, gold, silver, platinum, palladium, rhodium, aluminum, magnesium, lead, copper, tungsten, titanium, niobium, hafnium, vanadium, copper, molybdenum, manganese, or combinations thereof. Preferred metal particles include iron, nickel, cobalt, or combinations thereof.

[0085] Metal particles can be placed on a fibrous substrate or porous medium by reducing the salts of the aforementioned metals, such as chlorides, chlorates, sulfates, sulfides, nitrates, and phosphates. The metal salt is dissolved in a suitable solvent and then mixed with the porous particles to form a slurry. The slurry is then dried, causing the metal salt to deposit on the porous particles. The porous particles with the metal salt deposited on them are then subjected to a reducing gas stream (e.g., hydrogen, helium, etc.) at high temperature to reduce the salt to the metal.

[0086] The metal catalyst particles have average particle sizes of 2 nanometers to 50 micrometers, 10 nanometers to 25 micrometers, and 50 nanometers to 15 micrometers. The size of the metal particles depends on the salt concentration in the slurry relative to the porous particles. Higher salt concentrations result in larger metal catalyst particle sizes after reduction compared to porous particles.

[0087] Based on the total weight of the first composition, the metal catalyst particles are typically present on the porous particles in an amount of 0.5 to 10% by weight, preferably 1 to 5% by weight, and more preferably 1.5 to 4% by weight.

[0088] Flame retardant particles

[0089] Flame retardant particles are present in the flame retardant composition (or, when the flame retardant composition is added in two or more layers, in the first and second compositions). The flame retardant particles in the first composition may be the same as or "different" from those in the second composition. The term "different" implies a chemical difference—the chemical properties of the flame retardant particles in the first composition differ from the chemical properties of the flame retardant particles in the second composition.

[0090] Examples of suitable flame retardant particles are metal hydroxides, halogenated flame retardants, phosphorus-containing flame retardants, nitrogen-containing flame retardants, or combinations thereof.

[0091] Metal hydroxides act as flame retardants by reacting with water (either with themselves or with metal oxides) under heating. The water can be used to extinguish flames or, alternatively, to surround flammable materials, preventing oxygen from contacting and igniting them. In one embodiment, metal oxides can be used together with metal hydroxides as flame retardants. Examples of metal hydroxides are magnesium hydroxide, aluminum hydroxide, or combinations thereof. Examples of metal oxides are magnesium oxide, aluminum oxide, or combinations thereof.

[0092] In some embodiments, phosphorus-containing flame retardants include organophosphates. Exemplary organophosphate flame retardants include phosphates containing phenyl, substituted phenyl, or a combination of phenyl and substituted phenyl, resorcinol-based bisaryl phosphates such as resorcinol bis(diphenyl phosphate), and bisphenol-based ones such as bisphenol A bis(diphenyl phosphate). In some embodiments, the organophosphate is selected from tris(alkylphenyl) phosphates (e.g., CAS Reg. 89492-23-9 or CAS Reg. 78-33-1), resorcinol bis(diphenyl phosphate) (CAS Reg. 57583-54-7), bisphenol A bis(diphenyl phosphate) (CAS Reg. 181028-79-5), triphenyl phosphate (CAS Reg. 115-86-6), tris(isopropylphenyl) phosphates (e.g., CAS Reg. 68937-41-7), tert-butylphenyl diphenyl phosphate (CAS Reg. 56803-37-3), bis(tert-butylphenyl) phenyl phosphate (CAS Reg. 65652-41-7), tris(tert-butylphenyl) phosphate (CAS Reg. 78-33-1), and combinations thereof.

[0093] In some embodiments, the organophosphate comprises a bis(aryl) phosphate having the following formula:

[0094]

[0095] Wherein, R is independently C1-C each time it appears. 12 Alkylene; R 5 and R 6 Each time it appears, it is independently a C1-C5 alkyl group; R 1 R 2 and R 4 Independently, it is C1-C 12 hydrocarbon group; R 3 Each occurrence is independently C1-C 12 Hydrocarbon group; n is 1 to 25; and s1 and s2 are independently integers equal to 0, 1, or 2. In some embodiments, OR 1 OR 2 OR 3 and OR 4 It is independently derived from phenol, monoalkylphenol, dialkylphenol or trialkylphenol.

[0096] As will be readily understood by those skilled in the art, bis(aryl) phosphates are derived from bisphenols. Exemplary bisphenols include 2,2-bis(4-hydroxyphenyl)propane (bisphenol A), 2,2-bis(4-hydroxy-3-methylphenyl)propane, bis(4-hydroxyphenyl)methane, bis(4-hydroxy-3,5-dimethylphenyl)methane, and 1,1-bis(4-hydroxyphenyl)ethane. In some embodiments, bisphenols include bisphenol A.

[0097] In some embodiments, the flame retardant comprises a metal dialkylphosphine salt. As used herein, the term "metal dialkylphosphine salt" refers to a salt comprising at least one metal cation and at least one dialkylphosphine salt anion. In some embodiments, the metal dialkylphosphine salt has the following formula:

[0098]

[0099] Among them, R a and R b Each is independently a C1-C6 alkyl group; m is calcium, magnesium, aluminum, or zinc; and d is 2 or 3. R a and R b Examples include methyl, ethyl, n-propyl, isopropyl, n-butyl, tert-butyl, and n-pentyl. In some embodiments, R a and R b It is ethyl, M is aluminum, and d is 3 (i.e., the dialkyl phosphine salt is tris(diethylphosphine)aluminum).

[0100] In some embodiments, the flame retardant includes a nitrogen-containing flame retardant. Nitrogen-containing flame retardants include those comprising a nitrogen-containing heterocyclic base and a phosphate, pyrophosphate, or polyphosphate. In some embodiments, the nitrogen-containing flame retardant has the following formula:

[0101]

[0102] Wherein, g is from 1 to 10000, and the ratio of f to g is from 0.5:1 to 1.7:1, specifically from 0.7:1 to 1.3:1, and more specifically from 0.9:1 to 1.1:1. It should be understood that the molecular formula includes substances in which one or more protons are transferred from phosphate groups to melamine groups. When g is 1, the nitrogen-containing flame retardant is melamine phosphate (CAS Reg. No. 20208-95-1). When g is 2, the nitrogen-containing flame retardant is melamine pyrophosphate (CAS Reg. No. 15541 60-3). When g is greater than 2 on average, the nitrogen-containing flame retardant is melamine polyphosphate (CAS Reg. No. 56386-64-2). In some embodiments, the nitrogen-containing flame retardant is melamine pyrophosphate, melamine polyphosphate, or a mixture thereof. In some embodiments where the nitrogen-containing flame retardant is melamine polyphosphate, the average g value is greater than 2 to 10,000, specifically 5 to 1,000, and more specifically 10 to 500. In some embodiments where the nitrogen-containing flame retardant is melamine polyphosphate, the average g value is greater than 2 to 500. Methods for preparing melamine phosphate, melamine pyrophosphate, and melamine polyphosphate are known in the art and are commercially available. For example, melamine polyphosphate can be prepared by reacting polyphosphate with melamine, as described, for example, in U.S. Patent No. 6,025,419 to Kasowski et al., or by heating melamine pyrophosphate to constant weight at 290°C under nitrogen, as described in U.S. Patent No. 6,015,510 to Jacobson et al. In some embodiments, the nitrogen-containing flame retardant comprises melamine cyanurate.

[0103] Nitrogen-containing flame retardants can have low volatility. For example, in some embodiments, when heated from 25°C to 280°C at a rate of 20°C / min, specifically from 25°C to 300°C, more specifically from 25°C to 320°C, the nitrogen-containing flame retardant showed a weight loss of less than 1% by thermogravimetric analysis.

[0104] In some embodiments, the average particle size of the flame retardant particles is 10 nanometers to 1000 micrometers, preferably 100 nanometers to 500 micrometers, and more preferably 200 to 20 micrometers.

[0105] Based on the total weight of the flame retardant composition, the flame retardant particles are typically present in the flame retardant composition in an amount of 0.5 to 20% by weight, preferably 1 to 10% by weight, and more preferably 1.5 to 8% by weight.

[0106] Manufacturing of a single-layer flame retardant composition

[0107] To manufacture the flame retardant composition, porous particles, metal catalyst particles, and flame retardant particles are first mixed with a solvent to form a slurry. The slurry may contain a polymer binder (wherein the polymers are selected from the list above). A fiber substrate is then immersed in the slurry, allowing the slurry to penetrate the substrate. When the desired amount of slurry has penetrated into the fibers, the fiber substrate is dried to remove the solvent and any byproducts. The flame retardant composition, comprising the fiber substrate, porous media, metal catalyst particles, and flame retardant particles, is then added in a monolayer to the battery module and placed on top of the battery cell, as shown. Figure 1 As shown (see) Figure 1 The first layer (202) in the middle.

[0108] Optionally, the slurry (still in slurry form) after being mixed with the fiber substrate can be poured into the module to fill any unoccupied space (in the module).

[0109] It should be noted that the metal catalyst particles can be added in the form of a metal salt precursor to form a slurry. The metal catalyst particles are obtained by reducing the metal salt to leave the metal catalyst particles. An exemplary reducing agent is hydrogen.

[0110] Manufacturing of two-layer flame retardant compositions

[0111] When the flame retardant composition is added in two layers, the slurry contains only metal catalyst particles and flame retardant particles. The slurry is added to a fibrous matrix to form the first composition, and then separately added to porous particles to form the second composition. Each composition is then dried to remove solvents and any reaction precursors and byproducts. The compositions can be mixed together and added as a single layer as detailed above, or alternatively, as two separate layers as detailed below.

[0112] The first composition is added as a first layer to the battery module, while the second composition is disposed on top of the first layer in the battery module. For example... Figure 2 As shown, both the first and second layers are disposed between the battery casing and the battery cell. In one embodiment, there may be multiple layers comprising the first composition and the second composition, with each layer alternating with the others.

[0113] Figure 2 A battery module 100 having a first layer 202 (including a first composition) and a second layer 204 (including a second composition) is depicted. The second layer 204, comprising a fibrous substrate, is disposed on top of the first layer 202, which comprises porous particles. In one embodiment, the order of these layers may be reversed, with the first layer comprising porous particles disposed on top of the second layer comprising the fibrous substrate.

[0114] In yet another embodiment (not shown), the flame retardant composition may comprise multiple layers of a first composition and a second composition. In other words, the second layer comprising a fibrous substrate is disposed between the two first layers comprising porous particles. Alternatively, the first layer comprising porous particles may be disposed between the two layers comprising a fibrous substrate.

[0115] The solvent (used to prepare the slurry) can be water, an aqueous solvent (i.e., a solvent compatible with water), a solvent immiscible with water, or a combination thereof. Supercritical and / or superheated fluids may also be used as solvents in some compositions. Aqueous solvents are preferred. Liquid carbon dioxide is also preferred. Solvents capable of combining with water to form cosolvents capable of dissolving salts are ideal.

[0116] Solvents can be liquid aprotic polar solvents, polar protic solvents, nonpolar solvents, or combinations thereof. Liquid aprotic polar solvents such as propylene carbonate, ethylene carbonate, butyrolactone, acetonitrile, benzyl nitrile, nitromethane, nitrobenzene, sulfolane, dimethylformamide, N-methylpyrrolidone, etc., or combinations thereof, are commonly required for dissolving or slurrying salts and flame retardants. Polar protic solvents such as water, methanol, acetonitrile, nitromethane, ethanol, propanol, isopropanol, butanol, etc., or combinations thereof, can be used. Other nonpolar solvents such as benzene, toluene, dichloromethane, carbon tetrachloride, hexane, diethyl ether, tetrahydrofuran, etc., or combinations thereof, can also be used for dissolving or slurrying salts and flame retardants. Examples of preferred solvents are water, alcohols, tetrahydrofuran, acetone, or combinations thereof.

[0117] In another embodiment (not shown), the first composition 202 may be mixed with the second composition 204 after drying, and the mixture (of the first and second compositions) is applied as a monolayer to the top of the secondary battery cell.

[0118] Flame retardant compositions offer numerous advantages. They absorb combustible gases from the pores of porous substrates. They convert some combustible gases into expanding carbon, absorbing heat and slowing heat transfer during the expansion process. Flame retardants prevent flammable materials from burning.

[0119] While this disclosure has been described with reference to one or more exemplary embodiments, those skilled in the art will understand that various changes can be made and elements can be substituted with equivalents without departing from the scope of this disclosure. Furthermore, many modifications can be made to adapt particular situations or materials to the teachings of this disclosure without departing from the essential scope of this disclosure. Therefore, it is intended that this disclosure be limited to the specific embodiments disclosed as the best mode for carrying out this disclosure, but rather that this disclosure will include all embodiments falling within the scope of the claims.

Claims

1. A flame retardant composition for a battery module, comprising: The first composition comprises porous particles, on which first metal catalyst particles and first flame retardant particles are disposed. as well as The second composition comprises a fiber composition, the fiber composition comprising a fiber substrate having second metal catalyst particles and second flame retardant particles disposed thereon; wherein the first and second compositions are disposed on top of a plurality of battery cells in a battery module. The metal catalyst is used to convert carbon-containing gas into carbon-containing solid, and includes iron, nickel, cobalt, gold, silver, platinum, palladium, rhodium, aluminum, magnesium, lead, copper, tungsten, titanium, niobium, hafnium, vanadium, molybdenum, manganese or combinations thereof.

2. The flame retardant composition according to claim 1, wherein, The first composition and the second composition are mixed in a tight mixture and disposed in a single layer in the battery module.

3. The flame retardant composition according to claim 1, wherein, The first composition is disposed in a first layer, and the second composition is disposed in a second layer; The second layer is farther away from the plurality of battery cells than the first layer.

4. The flame retardant composition according to claim 1, wherein, At least one layer comprising the first composition is disposed between two layers comprising the second composition.

5. The flame retardant composition according to claim 1, wherein, At least one layer comprising the second composition is disposed between two layers comprising the first composition.

6. The flame retardant composition according to claim 1, wherein, The first metal catalyst particle is the same as the second metal catalyst particle.

7. The flame retardant composition according to claim 1, wherein, The first metal catalyst particles are different from the second metal catalyst particles.

8. The flame retardant composition according to claim 1, wherein, The first flame retardant particles are the same as the second flame retardant particles.

9. A battery module, comprising: Multiple secondary battery units arranged side by side; as well as A flame retardant composition disposed on top of multiple secondary battery cells; The flame retardant composition includes a first layer, on which a second layer is disposed; wherein the first layer comprises a first composition, and the second layer comprises a second composition; wherein the first composition comprises porous particles, on which first metal catalyst particles and first flame retardant particles are disposed; and wherein the second composition comprises a fiber composition comprising a fiber substrate on which second metal catalyst particles and second flame retardant particles are disposed. The metal catalyst is used to convert carbon-containing gas into carbon-containing solid, and includes iron, nickel, cobalt, gold, silver, platinum, palladium, rhodium, aluminum, magnesium, lead, copper, tungsten, titanium, niobium, hafnium, vanadium, molybdenum, manganese or combinations thereof.

10. The battery module according to claim 9, wherein, The porous particles are selected from the group consisting of aerogels, pyrolytic metal oxides, zeolites, metal-organic framework materials, or combinations thereof.

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