Lithium ion battery fire extinguishing agent and preparation method and application thereof

Abstract

The invention provides a lithium ion battery fire extinguishing agent and a preparation method and application thereof, and relates to the technical field of gel materials. The lithium ion battery fire extinguishing agent comprises temperature-sensitive type hydrogel powder and water, and the temperature-sensitive type hydrogel powder and the water exist independently and are mixed during use; wherein the temperature-sensitive hydrogel powder comprises the following components in parts by mass: 1-5 parts of a temperature-sensitive substance, 1-3 parts of a thickening agent, 1-3 parts of a flexibilizer, 3-5 parts of a flame retardant, 1-3 parts of a hydrocarbon surfactant, 1-5 parts of a cosolvent, 1-5 parts of a crosslinking monomer, 0.1-0.2 part of an initiator and 0.01-0.05 part of a crosslinking agent. The lithium ion battery fire extinguishing agent can rapidly absorb heat and cool when making contact with the surface of a high-temperature battery, meanwhile, a gel film is formed on the surface of the battery for continuous cooling, waste liquid biodegradation can be achieved, an efficient cooling environment-friendly gel fire extinguishing system is constructed, and the lithium ion battery fire extinguishing agent is especially suitable for rapid fire extinguishing and sealing control of the lithium battery.

Description

Technical Field

[0001] The present invention relates to the technical field of gel materials, and in particular to a lithium-ion battery fire extinguishing agent, a preparation method thereof, and applications thereof. Background Art

[0002] With increasing demand for low-carbon and environmentally friendly solutions, lithium-ion batteries (Li-ion Batteries) are widely used in electric vehicles, digital products, and energy storage systems due to their high energy density. However, they also suffer from the problem of violent thermal runaway reactions, difficult-to-suppress flames, and a chain reaction of heat spread, which can easily lead to casualties and property damage. When a Li-ion battery experiences thermal runaway, chemical reactions occur internally, releasing large amounts of flammable gases and heat. According to molecular thermal motion and Arrhenius's law, the rate of chemical reactions accelerates with increasing temperature, further exacerbating thermal runaway. Commonly used fire extinguishing agents such as dry powder, carbon dioxide, water mist, and foam are somewhat effective in conventional fires. However, when dealing with Li-ion batteries experiencing thermal runaway, they often face challenges such as low extinguishing efficiency, low cooling efficiency, environmental pollution, and high re-ignition rates. While perfluorohexanone, a commonly used fire extinguishing agent in energy storage systems, effectively extinguishes fires by interrupting the flame chain reaction, it still suffers from low cooling efficiency, high re-ignition rates, and environmental pollution. A large number of studies have confirmed that the photolysis, hydrolysis and thermal decomposition reactions of perfluorohexanone will produce substances that are harmful to the human body and the environment, such as perfluoropropionic acid, heptafluoropropane and hydrogen fluoride.

[0003] Therefore, research and development targeting lithium-ion battery fires is urgently needed to address the core challenges of fire extinguishing, re-ignition prevention, and environmental pollution. Prior art CN110935128A discloses a fire-proof and cooling hydrogel and its preparation method. The hydrogel comprises the following components by weight: 0.05-20 parts of a hydrogel thickener; 5-35 parts of a freezing point depressant; 1-30 parts of an expandable foaming material; 1-15 parts of an expandable flame retardant; 0.01-1 parts of a foaming agent; 1-15 parts of a gas generator; 0.01-1 parts of a fungicide; and at least 50 parts of water. While this hydrogel has some fire-proof and cooling effects, it does not demonstrate improved fire extinguishing efficiency or re-ignition prevention. Furthermore, it fails to address the environmental pollution caused by the F⁻ released after thermal runaway of lithium-ion batteries.

[0004] Therefore, there is an urgent need to provide a lithium-ion battery fire extinguishing agent that can comprehensively and effectively solve the core problems of difficult fire extinguishing, preventing re-ignition, and polluting the environment. Summary of the Invention

[0005] The present invention provides a lithium-ion battery fire extinguishing agent and its preparation method and application, which are used to solve the defects of lithium-ion battery fire extinguishing agents in the prior art, such as unsatisfactory fire extinguishing efficiency and anti-reignition effect. It realizes efficient fire extinguishing in application scenarios such as lithium-ion battery fires, has an anti-reignition effect, and can also effectively solve the environmental pollution problem caused by lithium-ion battery fires.

[0006] The present invention provides a lithium ion battery fire extinguishing agent, comprising a temperature-sensitive hydrogel powder and water, wherein the temperature-sensitive hydrogel powder and water exist independently and are mixed when used. The thermosensitive hydrogel powder includes the following components in parts by mass: 1~5 parts of temperature-sensitive substances, 1~3 parts of thickeners, 1~3 parts of flexibilizers, 3~5 parts of flame retardants, 1~3 parts of hydrocarbon surfactants, 1~5 parts of cosolvents, 1~5 parts of crosslinking monomers, 0.1~0.2 parts of initiators, and 0.01~0.05 parts of crosslinking agents.

[0007] According to the lithium ion battery fire extinguishing agent provided by the present invention, preferably, the mass of the temperature-sensitive hydrogel powder is 3-6% of the mass of water.

[0008] According to the lithium ion battery fire extinguishing agent provided by the present invention, preferably, the particle size of the temperature-sensitive hydrogel powder is 100-2000 mesh.

[0009] According to the lithium ion battery fire extinguishing agent provided by the present invention, preferably, the temperature-sensitive hydrogel powder comprises the following components in parts by mass: 1~3 parts of temperature-sensitive substances, 1~3 parts of thickeners, 2~3 parts of flexibilizers, 3~5 parts of flame retardants, 1~2 parts of hydrocarbon surfactants, 1~2 parts of cosolvents, 2~3 parts of crosslinking monomers, 0.1~0.2 parts of initiators, and 0.03~0.05 parts of crosslinking agents.

[0010] According to the lithium ion battery fire extinguishing agent provided by the present invention, preferably, the temperature-sensitive substance is methyl cellulose and / or sodium carboxymethyl cellulose; and / or the thickener is any one of sodium alginate, xanthan gum or gelatin; and / or the flexibilizer is one or more of polyvinyl alcohol, polyethylene glycol, and polypropylene glycol; and / or the cross-linking monomer is acrylic acid; and / or the cross-linking agent is acrylamide, N,N′-methylenebis(acrylamide), N-hydroxymethyl acrylamide, 2-acrylamide-2-methylpropanesulfonic acid; and / or the initiator is ammonium persulfate or potassium persulfate; and / or the flame retardant is one or more of phosphates, phosphonates or phosphates; and / or the hydrocarbon surfactant is one or more of nonionic alkyl glycoside, fatty alcohol polyoxyethylene ether JFC, zwitterionic cocamidopropyl betaine, sodium α-olefin sulfonate, sodium fatty alcohol polyoxyethylene ether sulfate, sodium lauryl sulfate or sodium lauryl sulfonate; and / or the cosolvent is one or more of urea, calcium chloride, calcium sulfate, ethylene glycol, propylene glycol or n-butanol.

[0011] According to the lithium-ion battery fire extinguishing agent provided by the present invention, preferably, the viscosity of the lithium-ion battery fire extinguishing agent is 1.63-2.73 mPa•s, and the surface tension is 28.5-29.7 mN / m.

[0012] The present invention also provides a method for preparing a lithium-ion battery fire extinguishing agent, comprising the following steps: The following steps are included.

[0013] S1. Mix the dehydrated methylcellulose and the flexibilizer according to the ratio, add water and stir at 50-70°C for 1-2 hours to obtain a transparent solution A; S2. The transparent solution A is heated to 50-70°C, and a cross-linking monomer solution B and a cross-linking agent having a pH of 6.5-7.5 are added to form a uniform mixed solution C; S3. Heat the mixed solution C to 60°C, add the initiator, flame retardant, hydrocarbon surfactant, and cosolvent according to the ratio, and react at a constant temperature for 30-60 minutes to obtain a gel. Dry and refine the mixture to obtain a thermosensitive hydrogel powder.

[0014] According to the method for preparing a lithium-ion battery fire extinguishing agent of the present invention, preferably, the drying in step S3 is performed at 80° C. for 12 to 24 hours.

[0015] The present invention also provides a lithium ion battery fire extinguishing agent or the use of the lithium ion battery fire extinguishing agent prepared according to the preparation method of the lithium ion battery fire extinguishing agent of the present invention in the preparation of a fire extinguishing device.

[0016] The present invention also provides a fire extinguishing device, which includes a lithium-ion battery fire extinguishing agent or a lithium-ion battery fire extinguishing agent prepared according to the preparation method of the lithium-ion battery fire extinguishing agent of the present invention.

[0017] Beneficial effects: The lithium-ion battery fire extinguishing agent provided by the present invention uses raw materials such as methyl cellulose, acrylamide, and acrylic acid to construct a three-dimensional gel network structure through polymerization. At the same time, phosphorus-based flame retardants, cosolvents, stabilizers, etc. are added. When in contact with the high-temperature battery surface, it can quickly absorb heat and cool down. At the same time, a gel film is formed on the battery surface to achieve continuous cooling efficiency. It can also significantly reduce the fluoride in the waste liquid after injection and realize the biodegradation of the waste liquid. This constructs an environmentally friendly gel fire extinguishing system with high-efficiency cooling, which is particularly suitable for rapid response and on-site sealing of thermal runaway fires in lithium battery modules. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to make the contents of the present invention more clearly understood, the present invention is further described in detail below based on specific embodiments of the present invention in conjunction with the accompanying drawings.

[0019] Figure 1 FTIR spectra of the temperature-sensitive hydrogel of methyl cellulose, acrylic acid, polyethylene glycol and the lithium-ion battery fire extinguishing agent of Example 1.

[0020] Figure 2 This is a diagram of fluoride ion absorption in the waste liquid after fire extinguishing spraying.

[0021] Figure 3 Diagram of the fire extinguishing device for the fire extinguishing experiment.

[0022] Figure 4 Figure 3 is a graph showing the temperature change over time during the LFP battery fire extinguishing process, where (a) is the blank group, (b) is the water mist fire extinguishing, and (c) is the fire extinguishing using the fire extinguishing agent of Example 1.

[0023] Figure 5 Figure 2 is a graph showing the temperature variation over time during the NCM battery fire extinguishing process, where (a) is a blank group, (b) is a water mist fire extinguishing group, and (c) is a fire extinguishing group using the fire extinguishing agent of Example 1. DETAILED DESCRIPTION

[0024] The following examples are intended to illustrate the present invention but are not intended to limit the scope of the invention. Where specific techniques or conditions are not specified in the examples, the methods were performed according to those described in the literature in the art or according to the product instructions. Where the manufacturer of the reagents or instruments is not specified, all are conventional products available through regular channels.

[0025] The present invention provides a lithium ion battery fire extinguishing agent, comprising a temperature-sensitive hydrogel powder and water, wherein the temperature-sensitive hydrogel powder and water exist independently and are mixed when used. The thermosensitive hydrogel powder includes the following components in parts by mass: 1~5 parts of temperature-sensitive substances, 1~3 parts of thickeners, 1~3 parts of flexibilizers, 3~5 parts of flame retardants, 1~3 parts of hydrocarbon surfactants, 1~5 parts of cosolvents, 1~5 parts of crosslinking monomers, 0.1~0.2 parts of initiators, and 0.01~0.05 parts of crosslinking agents.

[0026] Among them, it should be noted that: The lithium-ion battery fire extinguishing agent of the present invention uses raw materials such as methyl cellulose, acrylamide, and acrylic acid, and constructs a three-dimensional gel network structure through polymerization. At the same time, phosphorus-based flame retardants, cosolvents, stabilizers, etc. are added to form a highly efficient and clean lithium-ion battery fire extinguishing agent. The lithium-ion battery fire extinguishing agent of the present invention is not only temperature-sensitive but also has a three-dimensional gel network structure, which can provide a larger specific surface area for water storage, so that it can quickly release a large amount of water molecules when it contacts the battery surface. The fire extinguishing agent can quickly absorb heat and cool down when it contacts the high-temperature battery surface, and at the same time form a gel film on the battery surface, effectively blocking oxygen and quickly absorbing heat and cooling. When the fire extinguishing agent just contacts the battery surface, the water molecules released are free water molecules in the three-dimensional gel network. The formed gel film contains water molecules that are tightly connected to the internal three-dimensional gel network structure through chemical bonds. After the film is formed, this part of the water molecules can be continuously released to achieve a continuous cooling effect.

[0027] Moreover, because during the fire extinguishing process, fluoride is adsorbed inside the gel through the three-dimensional gel network, and on the other hand, new compound precipitation is formed through the coordination effect between metal ions, the fire extinguishing agent of the present invention can also significantly reduce the fluoride content in the waste liquid after injection, thereby achieving biodegradation of the waste liquid.

[0028] The temperature-sensitive hydrogel of the present invention also has excellent adhesion and structural stability, and can continuously act on the battery surface to prevent re-ignition.

[0029] In summary, the fire extinguishing agent of the present invention has good temperature-sensitive responsiveness, heat absorption cooling performance, and continuous cooling performance. It can reduce the impact of the steam layer on cooling in the Leidenfrost effect, and quickly gel, cool down, and prevent re-ignition in the event of a thermal runaway fire in a lithium-ion battery. It provides an efficient and safe emergency protection method for electric vehicles, energy storage systems, etc., and is particularly suitable for rapid response and on-site sealing of thermal runaway fires in lithium battery modules. In addition, the fire extinguishing agent can be adapted to a variety of water-based fire extinguishing agent application scenarios and is suitable for emergency disposal of lithium battery fires in energy storage, electric vehicles, transportation, and other fields. It has comprehensive advantages such as simple structure, safe use, and environmental friendliness.

[0030] In the temperature-sensitive hydrogel powder of the present invention, the thickener is used to increase the viscosity of the agent so that it can adhere to the battery surface; the flexibilizer is used to reduce the contact angle to facilitate the spreading of the liquid on the battery surface; and the hydrocarbon surfactant is used to generate foam and reduce surface tension.

[0031] By controlling the synergistic dosage of each component, a good overall gelling effect and improvement of comprehensive performance can be achieved.

[0032] In certain embodiments, in order to achieve better comprehensive effects, the mass of the thermosensitive hydrogel powder is preferably 3-6% of the mass of water, for example, 3%, 4%, 5%, 6%, and any combination thereof.

[0033] In certain embodiments, in order to provide a larger specific surface area, be easier to dissolve, and prevent agglomeration during dissolution, the particle size of the thermosensitive hydrogel powder is preferably 100-2000 mesh, more preferably 200 mesh.

[0034] In certain embodiments, in order to further improve the effect, the temperature-sensitive hydrogel powder preferably includes the following components in parts by weight: 1~3 parts of temperature-sensitive substances, 1~3 parts of thickeners, 2~3 parts of flexibilizers, 3~5 parts of flame retardants, 1~2 parts of hydrocarbon surfactants, 1~2 parts of cosolvents, 2~3 parts of crosslinking monomers, 0.1~0.2 parts of initiators, and 0.03~0.05 parts of crosslinking agents.

[0035] For example, in some specific embodiments, it may be: 3 parts of temperature-sensitive substances, 2 parts of thickeners, 2 parts of flexibilizers, 3 parts of flame retardants, 1 part of hydrocarbon surfactants, 1 part of cosolvents, 2 parts of crosslinking monomers, 0.1 parts of initiators, and 0.03 parts of crosslinking agents; Or 1 part of temperature-sensitive substance, 1 part of thickener, 2 parts of flexibilizer, 5 parts of flame retardant, 2 parts of hydrocarbon surfactant, 2 parts of cosolvent, 2 parts of crosslinking monomer, 0.2 parts of initiator, 0.05 parts of crosslinking agent; Or 1 part of temperature-sensitive substance, 3 parts of thickener, 3 parts of flexibilizer, 3 parts of flame retardant, 2 parts of hydrocarbon surfactant, 2 parts of cosolvent, 3 parts of crosslinking monomer, 0.2 parts of initiator, 0.03 parts of crosslinking agent.

[0036] The lithium-ion battery fire extinguishing agent of the present invention does not impose specific restrictions on the components of the temperature-sensitive hydrogel powder; any components that can be realized in the art can be used. In certain embodiments, the temperature-sensitive substance can be, for example, methylcellulose and / or sodium carboxymethylcellulose; The thickener may be, for example, any one of sodium alginate, xanthan gum or gelatin; The cross-linking monomer may be, for example, acrylic acid; The cross-linking agent may be, for example, N,N′-methylenebis(acrylamide); The initiator may be, for example, ammonium persulfate (APS); The flame retardant may be, for example, one or more of phosphates, phosphonates or phosphates; The hydrocarbon surfactant may be one or more of nonionic alkyl glycoside, fatty alcohol polyoxyethylene ether JFC, zwitterionic cocamidopropyl betaine, sodium α-olefin sulfonate, sodium fatty alcohol polyoxyethylene ether sulfate, sodium lauryl sulfate or sodium lauryl sulfonate; The cosolvent may be one or more of urea, ethylene glycol, propylene glycol or n-butanol.

[0037] In certain specific embodiments, the phosphate flame retardant mentioned in the present invention can be specifically one or more of dimethyl phosphate, triethyl phosphate, tributyl phosphate and triphenyl phosphate; The phosphonate flame retardant may be selected from one or more of dimethyl methylphosphonate and N,N-phenylenediamino (2-hydroxy) dibenzyl tetraethyl phosphate; The phosphate flame retardant may be ammonium polyphosphate or trishydroxymethylphosphine oxide.

[0038] The lithium-ion battery fire extinguishing agent of the present invention introduces methyl cellulose as a temperature-sensitive hydrogel base, combined with a variety of biodegradable and environmentally friendly cross-linking agents, lubricants, flame retardants and other ingredients to construct an environmentally friendly gel fire extinguishing system with high-efficiency cooling. It has excellent adhesion and structural stability. The viscosity of the lithium-ion battery fire extinguishing agent is 1.63~2.73mPa•s and the surface tension is 28.5~29.7mN / m.

[0039] The surface tension of the lithium-ion battery fire extinguishing agent of the present invention is significantly lower than the approximately 40 mN / m of the prior art. Surface tension affects the extinguishing agent's ability to wet electrode materials or the internal structure of the battery. Lower surface tension helps the extinguishing agent spread quickly and penetrate into the thermal runaway zone, increasing the contact area with the active material and improving fire extinguishing efficiency.

[0040] At the same time, the viscosity of the lithium-ion battery fire extinguishing agent of the present invention is 1.63~2.73mPa•s. Appropriately increasing the battery viscosity can enhance the adhesion of the fire extinguishing agent on the surface of objects, improve the adhesion on the surface of objects in application scenarios such as lithium-ion batteries, while maintaining the stability of the film-forming structure and reducing the flow tendency, thereby extending the effective coverage time and preventing re-ignition.

[0041] In certain specific embodiments, the present invention further provides a method for preparing a lithium-ion battery fire extinguishing agent, comprising the following steps: S1. Mix the dehydrated methylcellulose and the flexibilizer according to the ratio, add water and stir at 50-70°C for 1-2 hours to obtain a transparent solution A; S2. The transparent solution A is heated to 50-70°C, and a cross-linking monomer solution B and a cross-linking agent having a pH of 6.5-7.5 are added to form a uniform mixed solution C; S3. Heat the mixed solution C to 60°C, add the initiator, flame retardant, hydrocarbon surfactant, and cosolvent according to the ratio, and react at a constant temperature for 30-60 minutes to obtain a gel. Dry and refine the mixture to obtain a thermosensitive hydrogel powder.

[0042] In certain embodiments, the methylcellulose and the flexibilizer mentioned in step S1 of the present invention and the cross-linking agent in step S2 are all subjected to a dehydration treatment, which can be performed by the following method: The methyl cellulose, the flexibilizer and the cross-linking agent (such as N,N'-methylenebisacrylamide) are placed in a vacuum drying oven at 60°C and dried for 6 to 8 hours to obtain the dehydrated methyl cellulose, the flexibilizer and the cross-linking agent.

[0043] In certain specific embodiments, the cross-linking monomer solution B with a pH of 6.5 to 7.5 in step S2 of the present invention can be prepared by referring to the following method: The acrylic acid monomer is mixed with the sodium hydroxide solution and the pH is adjusted to 6.5 to 7.5 to obtain a cross-linking monomer solution B with a pretreated pH of 6.5 to 7.5.

[0044] In certain specific embodiments, the drying treatment in the drying and refining step S3 is drying at 80° C. for 12 to 24 hours, and the refining can be performed by pulverizing and then filtering through a sieve to obtain a temperature-sensitive hydrogel powder of a target particle size.

[0045] The lithium-ion battery fire extinguishing agent of the present invention comprises independently existing temperature-sensitive hydrogel powder and water. When in use, the prepared temperature-sensitive hydrogel powder is mixed with water at room temperature to obtain the stable water-based fire extinguishing agent of the present invention for use in fire extinguishing devices.

[0046] On the other hand, the present invention also provides a lithium ion battery fire extinguishing agent or the use of the lithium ion battery fire extinguishing agent prepared according to the preparation method of the lithium ion battery fire extinguishing agent provided by the present invention in the preparation of a fire extinguishing device On the other hand, the present invention also provides a fire extinguishing device, which contains the lithium ion battery fire extinguishing agent provided by the present invention or the lithium ion battery fire extinguishing agent prepared according to the preparation method of the lithium ion battery fire extinguishing agent provided by the present invention.

[0047] Example 1 A lithium-ion battery fire extinguishing agent includes a temperature-sensitive hydrogel powder and water. The temperature-sensitive hydrogel powder and water exist independently and are mixed when used. The thermosensitive hydrogel powder includes the following components in parts by mass: 3 parts of temperature-sensitive substance methyl cellulose, 2 parts of thickener, 2 parts of flexibilizer, 3 parts of flame retardant, 1 part of hydrocarbon surfactant, 1 part of cosolvent, 2 parts of cross-linking monomer, 0.1 part of initiator, 0.03 part of cross-linking agent.

[0048] The specific preparation method of the lithium ion battery fire extinguishing agent of the above embodiment 1 is as follows: S1. Place 3 parts of temperature-sensitive methylcellulose and 2 parts of flexible polyethylene glycol in a vacuum drying oven at 60°C and dry for 6 hours. After removing the moisture, mix the temperature-sensitive methylcellulose and the flexible polyethylene glycol to obtain mixed powder A. The mixed powder A was slowly added into 80 mL of deionized water, placed in a three-necked flask and stirred in a 60°C water bath for 1.5 hours to obtain a high-viscosity transparent solution A; S2 In another container, 2.0 g of cross-linking monomer acrylic acid was mixed with 0.5 mL of sodium hydroxide solution (0.5 mol / L) and the pH was adjusted to about 7.0 to obtain cross-linking monomer solution B. Slowly dropwise add crosslinking monomer solution B and 0.03 parts of crosslinking agent N,N′-methylenebis(acrylamide) dried in a vacuum drying oven at 60°C for 6 hours to the high viscosity transparent solution A, stirring for 30 minutes to form a uniform reaction mixture C; S3. In a 60°C water bath, add 0.1 parts of initiator ammonium persulfate (APS), 3 parts of phosphate flame retardant, 1 part of hydrocarbon surfactant sodium α-olefin sulfonate, 1 part of co-solvent calcium chloride, and 1 part of thickener sodium alginate to the reaction mixture C, and continue to stir and react at a constant temperature for 45 minutes to obtain a gel. Transfer the obtained gel to a vacuum drying oven and dry it at 80°C for 12 to 24 hours to obtain a solid gel block. After cooling, crush it and filter it through a 200-mesh sieve to obtain a temperature-sensitive hydrogel powder.

[0049] The temperature-sensitive hydrogel powder of the lithium-ion battery fire extinguishing agent of Example 1 and methyl cellulose, acrylic acid, and polyethylene glycol were subjected to infrared characterization detection. Specifically, the FTIR spectra of methyl cellulose, acrylic acid, polyethylene glycol and the temperature-sensitive hydrogel of the lithium-ion battery fire extinguishing agent of Example 1 are as follows: Figure 1 shown.

[0050] from Figure 1The broad, intense absorption band at 3446 cm⁻¹ is primarily attributed to the abundant hydroxyl (-OH) stretching vibrations in methylcellulose (MC) and sodium polyacrylate (PAAS) molecules. The broadness of this peak reflects the extensive intermolecular hydrogen bonding network and the presence of some bound water molecules within the system. The absorption peak at 1627 cm⁻¹ can be attributed to the asymmetric stretching vibrations of the carboxylate (–COO⁻) in PAAS, with a slight shift in position, likely due to hydrogen bonding interactions. The strong absorption peak at 1074 cm⁻¹ corresponds to the stretching vibrations of the C–O–C ether bonds in PEG and MC, indicating that these two components play a connecting role in constructing the hydrogel network. The absorption peak at 954 cm⁻¹ is associated with the C–H rocking vibrations of the glycosidic bonds in the MC molecule. Changes in the infrared spectrum indicate that acrylic acid forms sodium polyacrylate through cross-linking, forming a three-dimensional gel network structure.

[0051] Example 2 A lithium-ion battery fire extinguishing agent includes a temperature-sensitive hydrogel powder and water. The temperature-sensitive hydrogel powder and water exist independently and are mixed when used. The thermosensitive hydrogel powder includes the following components in parts by mass: 1 part of temperature-sensitive substance sodium carboxymethyl methylcellulose, 1 part of thickener, 2 parts of flexibilizer, 5 parts of flame retardant, 2 parts of hydrocarbon surfactant, 2 parts of cosolvent, 2 parts of crosslinking monomer, 0.2 parts of initiator, 0.05 parts of crosslinking agent.

[0052] The specific preparation method of the lithium ion battery fire extinguishing agent of the above embodiment 1 is as follows: S1. Sodium carboxymethyl cellulose and the flexibilizer polyvinyl alcohol were placed in a vacuum drying oven at 60°C and dried for 6 hours. After removing the moisture, the temperature-sensitive substance methyl cellulose and the flexibilizer polyethylene glycol were weighed and mixed according to the mass ratio to obtain a mixed powder A. The mixed powder A was slowly added into 80 mL of deionized water, placed in a three-necked flask and stirred in a 60°C water bath for 1.5 hours to obtain a high-viscosity transparent solution A; S2. In another container, 2.0 g of cross-linking monomer acrylic acid was mixed with 0.5 mL of sodium hydroxide solution (0.5 mol / L) and the pH was adjusted to about 7.0 to obtain solution B. Solution B and the crosslinker N,N′-methylenebis(acrylamide) which had been dried in a vacuum drying oven at 60°C for 6 hours were slowly added dropwise to solution A while stirring for 30 minutes to form a uniform reaction mixture C. S3. In a 60°C water bath, add 0.2 parts of initiator ammonium persulfate (APS), 5 parts of phosphate flame retardant, 2 parts of hydrocarbon surfactant fatty alcohol polyoxyethylene ether JFC, 2 parts of cosolvent n-butanol, and 1 part of thickener xanthan gum to Solution C. Continue stirring at a constant temperature for 45 minutes to obtain a gel. Transfer the obtained gel to a vacuum drying oven and dry it at 80°C for 12 to 24 hours to obtain a solid gel block. After cooling, crush it and filter it through a 200-mesh sieve to obtain a temperature-sensitive hydrogel powder.

[0053] Example 3 A lithium-ion battery fire extinguishing agent includes a temperature-sensitive hydrogel powder and water. The temperature-sensitive hydrogel powder and water exist independently and are mixed when used. The thermosensitive hydrogel powder includes the following components in parts by mass: 1 part of temperature-sensitive substance carboxymethyl methylcellulose, 3 parts of thickener, 3 parts of flexibilizer, 3 parts of flame retardant, 2 parts of hydrocarbon surfactant, 2 parts of cosolvent, 3 parts of crosslinking monomer, 0.2 parts of initiator, 0.03 parts of crosslinking agent.

[0054] The specific preparation method of the lithium ion battery fire extinguishing agent of the above embodiment 1 is as follows: S1. Carboxymethyl cellulose and plier polypropylene glycol were placed in a vacuum drying oven at 60°C and dried for 6 hours. After removing the moisture, the temperature-sensitive substance methyl cellulose and plier polyethylene glycol were weighed and mixed according to the mass ratio to obtain mixed powder A. The mixed powder A was slowly added into 80 mL of deionized water, placed in a three-necked flask and stirred in a 60°C water bath for 1.5 hours to obtain a high-viscosity transparent solution A; S2. In another container, 3.0 g of cross-linking monomer acrylic acid was mixed with 0.5 mL of sodium hydroxide solution (0.5 mol / L) and the pH was adjusted to about 7.0 to obtain solution B. Solution B and the crosslinker N,N′-methylenebis(acrylamide) which had been dried in a vacuum drying oven at 60°C for 6 hours were slowly added dropwise to solution A while stirring for 30 minutes to form a uniform reaction mixture C. S3. In a 60°C water bath, add 0.2 parts of initiator ammonium persulfate (APS), 3 parts of phosphonate flame retardant, 2 parts of hydrocarbon surfactant zwitterionic cocamidopropyl betaine, 2 parts of cosolvent ethylene glycol, and 3 parts of gelatin to Solution C. Continue stirring at a constant temperature for 45 minutes to obtain a gel. Transfer the obtained gel to a vacuum drying oven and dry it at 80°C for 12 to 24 hours to obtain a solid gel block. After cooling, crush it and filter it through a 200-mesh sieve to obtain a temperature-sensitive hydrogel powder.

[0055] Comparative Example 1 A lithium-ion battery fire extinguishing agent was prepared using the same method as in Example 1, except that N,N'-methylenebisacrylamide (a crosslinking agent) was omitted. Results showed that the final product failed to form a stable gel structure and delaminated after prolonged storage, making it unstorable.

[0056] Comparative Example 2 The same method as in Example 1 was used, except that ammonium persulfate (initiator) was removed. Similar to Comparative Example 2, delamination occurred and the product could not be stored for a long time.

[0057] Comparative Example 3 The same method as in Example 1 was used, except that calcium chloride (solvent) was removed. - , the effect is almost the same as the blank test.

[0058] Example 4 The application process of the fire extinguishing agent of this embodiment is as follows: the powdered temperature-sensitive colloid of each embodiment and comparative example is added to water and stirred evenly to obtain a fire extinguishing agent with a mass concentration of 3%, and then a lithium battery fire extinguishing test is carried out. The results are shown in Table 1.

[0059] Example 5 The application process of the temperature-sensitive hydrogel fire extinguishing additive of this embodiment is as follows: the powdered temperature-sensitive colloid of each embodiment and comparative example is added to water and stirred evenly to obtain a fire extinguishing agent with a mass concentration of 6%. The lithium battery fire extinguishing test is carried out. The results are shown in Table 2.

[0060] Example 6 The application process of the temperature-sensitive hydrogel fire extinguishing additive of this embodiment is as follows: the powdered temperature-sensitive colloid of each embodiment and comparative example is added to water and stirred evenly to obtain a fire extinguishing agent with a mass concentration of 9%, and then a lithium battery fire extinguishing test is carried out. The results are shown in Table 3.

[0061] Example 7 Deionized water and a commercial water-based fire extinguishing agent were used to carry out lithium battery fire extinguishing experiments, and the temperature-sensitive hydrogel fire extinguishing additives of Example 1, Example 2, and Example 3 were used to carry out lithium battery thermal runaway fire extinguishing experiments. Figure 3 shown.

[0062] The effect of the above fire extinguishing agent is verified by Example 7.

[0063] The following standards were used for the various indicators of the embodiments and comparative examples of the present invention: Viscosity test: according to GB / T5561-2012 Chemical Reagent Viscosity Determination Method; Surface tension test: in accordance with GB / T5549-2010 Determination of liquid surface tension (pull-off method); pH value test: refer to GB / T9724-2007 General Rules for Determination of pH Value of Chemical Reagents; Conductivity test: refer to "GB / T14506.28-2010 Determination of electrical conductivity of water - Conductivity method"; fire extinguishing time and re-ignition test: refer to "GB17945-2010 General technical conditions for fire extinguishing agents of fire products".

[0064] Among them, the lower the surface tension, the more conducive it is for the fire extinguishing agent to penetrate into the thermal runaway area of ​​the battery, improve the fire extinguishing efficiency, and prevent re-ignition. The increase in viscosity also helps the fire extinguishing agent adhere to the surface and prevent re-ignition.

[0065] Conductivity affects the electrical conductivity of the fire extinguishing agent. If the conductivity is high, external short circuits between batteries are likely to occur, forming a current path.

[0066] pH can reflect the acidity or alkalinity of the fire extinguishing agent. If it is too acidic or too alkaline, it will be difficult to preserve and will corrode the metal.

[0067] The specific results are shown in Tables 1~3.

[0068] Table 1.

[0069] Table 2.

[0070] Table 3

[0071] The indicators in Tables 1 to 3 above are tested with reference to the following standards: Viscosity test: according to GB / T5561-2012 Chemical Reagent Viscosity Determination Method; Surface tension test: in accordance with GB / T5549-2010 Determination of liquid surface tension (pull-off method); pH value test: refer to GB / T9724-2007 General Rules for Determination of pH Value of Chemical Reagents; Conductivity test: refer to "GB / T14506.28-2010 Determination of electrical conductivity of water - Conductivity method"; fire extinguishing time and re-ignition test: refer to "GB17945-2010 General technical conditions for fire extinguishing agents of fire products".

[0072] As can be seen from Tables 1 to 3, the viscosity of the fire extinguishing agent of the present invention is significantly improved compared with the comparative example at different usage concentrations, indicating that the lithium ion battery fire extinguishing agent of the present invention has better adhesion, which is more conducive to forming a gel film on the battery surface, effectively blocking oxygen and rapidly absorbing heat and cooling, achieving a continuous cooling effect and long-term coverage to prevent re-ignition.

[0073] In addition, the fire extinguishing agent of the present invention has a significantly lower surface tension than the comparative example at different usage concentrations. The lower surface tension is more conducive to improving the wetting ability of the electrode material or the internal structure of the battery, helping the fire extinguishing agent to spread quickly and penetrate into the thermal runaway area, increasing the contact area with the active substance, and improving the fire extinguishing efficiency.

[0074] However, commercial water-based fire extinguishing agents have a large surface tension and cannot spread effectively and quickly and penetrate into the thermal runaway area, thus causing it to reignite.

[0075] Figure 2 This is the fluoride ion absorption diagram in the waste liquid after fire extinguishing spray. Figure 2 It can be seen that after deionized water extinguishes the fire, F ⁻ The release amount is the highest, indicating that deionized water as a solvent absorbs the F released after the battery thermal runaway ⁻ , while the fluoride ion content in the sprayed waste liquid in Example 1 is low, which proves that it is absorbed by the fire extinguishing agent. The lithium ion battery fire extinguishing agent prepared in Example 1 can absorb a large amount of F ⁻ , proving its environmental friendliness.

[0076] Figure 4 The temperature of the LFP battery fire extinguishing process changes with time, where (a) is the blank group, no fire extinguishing treatment is performed, so the curve temperature does not show a sudden drop, (b) is the fine water mist fire extinguishing, and (c) is the fire extinguishing using the fire extinguishing agent of Example 1, where 1#~5# correspond to Figure 3 Thermocouple arrangement on the LFP cell, T1-T5.

[0077] Figure 5 The temperature changes over time during the fire extinguishing process of NCM batteries, where (a) is the blank group without fire extinguishing treatment, (b) is the fire extinguishing with fine water mist, and (c) is the fire extinguishing with the fire extinguishing agent of Example 1, where 1#~5# correspond to Figure 3 Thermocouple arrangement on the LFP cell, T1-T5.

[0078] from Figure 4 and Figure 5 It can be seen that the fire extinguishing and cooling performance of the fire extinguishing agent of the present invention is better than that of fine water mist. While the fire extinguishing agent quickly extinguishes the flame of the lithium-ion battery, the hydrogel attached to the battery surface absorbs a large amount of heat to achieve a continuous cooling effect. At the same time, the gel film formed on the battery surface acts as a heat insulator and suppresses thermal runaway of the battery.

[0079] The lithium-ion battery fire extinguishing agent provided by this invention can gel under high-temperature conditions associated with lithium-ion battery fires, effectively blocking oxygen and rapidly absorbing heat to reduce temperatures. The gel also exhibits excellent adhesion and structural stability, allowing it to continuously adhere to the battery surface and prevent re-ignition. Experimental results demonstrate that the gel fire extinguishing agent can extinguish lithium battery flames within seconds and rapidly reduce the battery surface temperature.

[0080] In addition, the lithium-ion battery fire extinguishing agent provided by the present invention is composed of degradable or low-toxic ingredients such as methyl cellulose, polyethylene glycol, and acrylic acid. It has good environmental adaptability and safety in use. Its preparation process is simple and it can be processed into powder or liquid form. It is suitable for portable spraying or embedded protection. It is particularly suitable for fire risk scenarios such as electric vehicles, energy storage systems, lithium battery transportation and warehousing, and has broad engineering application prospects and promotion value.

[0081] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A lithium-ion battery fire extinguishing agent, characterized in that: It includes thermosensitive hydrogel powder and water. The thermosensitive hydrogel powder and water exist independently and are mixed when used. The thermosensitive hydrogel powder includes the following components in parts by mass: 1~5 parts of temperature-sensitive substances, 1~3 parts of thickeners, 1~3 parts of flexibilizers, 3~5 parts of flame retardants, 1~3 parts of hydrocarbon surfactants, 1~5 parts of cosolvents, 1~5 parts of crosslinking monomers, 0.1~0.2 parts of initiators, and 0.01~0.05 parts of crosslinking agents.

2. The lithium-ion battery fire extinguishing agent according to claim 1, characterized in that: The mass of the thermosensitive hydrogel powder is 3-6% of the mass of water.

3. The lithium-ion battery fire extinguishing agent according to claim 1, characterized in that: The particle size of the temperature-sensitive hydrogel powder is 100~2000 mesh.

4. The lithium-ion battery fire extinguishing agent according to any one of claims 1 to 3, characterized in that The thermosensitive hydrogel powder includes the following components in parts by mass: 1~3 parts of temperature-sensitive substances, 1~3 parts of thickeners, 2~3 parts of flexibilizers, 3~5 parts of flame retardants, 1~2 parts of hydrocarbon surfactants, 1~2 parts of cosolvents, 2~3 parts of crosslinking monomers, 0.1~0.2 parts of initiators, and 0.03~0.05 parts of crosslinking agents.

5. The lithium-ion battery fire extinguishing agent according to any one of claims 1 to 3, characterized in that: The temperature-sensitive substance is methylcellulose and / or sodium carboxymethylcellulose; and / or the thickener is any one of sodium alginate, xanthan gum or gelatin; and / or the flexibilizer is one or more of polyvinyl alcohol, polyethylene glycol, and polypropylene glycol; and / or the cross-linking monomer is acrylic acid; and / or the cross-linking agent is acrylamide, N,N′-methylenebis(acrylamide), N-hydroxymethyl acrylamide, 2-acrylamide-2-methylpropanesulfonic acid; and / or the initiator is ammonium persulfate or potassium persulfate; and / or the flame retardant is one or more of phosphates, phosphonates or phosphates; and / or the hydrocarbon surfactant is one or more of nonionic alkyl glycoside, fatty alcohol polyoxyethylene ether JFC, zwitterionic cocamidopropyl betaine, sodium α-olefin sulfonate, sodium fatty alcohol polyoxyethylene ether sulfate, sodium lauryl sulfate or sodium lauryl sulfonate; and / or the cosolvent is one or more of urea, calcium chloride, calcium sulfate, ethylene glycol, propylene glycol or n-butanol.

6. The lithium-ion battery fire extinguishing agent according to any one of claims 1 to 3, characterized in that: The viscosity of lithium-ion battery fire extinguishing agent is 1.63~2.73mPa•s, and the surface tension is 28.5~29.7mN / m.

7. A method for preparing the lithium-ion battery fire extinguishing agent according to any one of claims 1 to 6, characterized in that: The steps include: S1. The dehydrated methylcellulose and the flexibilizer were mixed in a ratio and dissolved evenly in water to obtain a transparent solution A; S2. The transparent solution A is heated to 50-70°C, and a cross-linking monomer solution B and a cross-linking agent having a pH of 6.5-7.5 are added to form a uniform mixed solution C; S3. Heat the mixed solution C to 60°C, add the initiator, flame retardant, hydrocarbon surfactant, and cosolvent according to the ratio, and react at a constant temperature for 30-60 minutes to obtain a gel. Dry and refine the mixture to obtain a thermosensitive hydrogel powder.

8. The method for preparing a lithium-ion battery fire extinguishing agent according to claim 7, characterized in that: The drying in step S3 is performed at 80° C. for 12 to 24 hours.

9. Use of the lithium ion battery fire extinguishing agent according to any one of claims 1 to 6 or the lithium ion battery fire extinguishing agent according to claim 7 or 8 in preparing a fire extinguishing device.

10. A fire extinguishing device, characterized in that: A lithium-ion battery fire extinguishing agent comprising the lithium-ion battery fire extinguishing agent according to any one of claims 1 to 6 or prepared by the preparation method of the lithium-ion battery fire extinguishing agent according to claim 7 or 8.

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