Special fire extinguishing agent for lithium battery

Abstract

The invention discloses a fire extinguishing agent special for a lithium battery, and belongs to the technical field of fire extinguishing agents. The special fire extinguishing agent for the lithium battery comprises the following components in parts by weight: 15-25 parts of organic modified bentonite, 30-40 parts of polymer microspheres, 5-8 parts of a composite flame retardant, 2-4 parts of a surfactant and 80-100 parts of hydrogel, the polymer microsphere comprises a core material and a shell, the core material is 2-acrylamido-2-methylpropanesulfonate and silane modified porous calcium carbonate, and the shell is an acrylate copolymer; the organic modified bentonite is imidazoline quaternary ammonium salt modified sodium bentonite. The special fire extinguishing agent for the lithium battery, provided by the invention, is environment-friendly in raw materials, relatively low in cost, excellent in insulativity, good in fire extinguishing and cooling effects, high in cooling rate, capable of effectively and quickly inhibiting flames and preventing thermal runaway of the lithium battery, high in reignition resistance and high in utilization rate.

Description

Technical Field

[0001] The present invention belongs to the technical field of fire extinguishing agents, and in particular relates to a fire extinguishing agent special for lithium ion batteries and a preparation method thereof. Background Art

[0002] Lithium-ion batteries, with their advantages of high energy density, high conversion efficiency, and fast response speed, have become a key development direction for electrochemical energy storage technology, and their share in electrochemical energy storage continues to increase. However, due to their physical and chemical properties, lithium-ion batteries are inevitably subject to damage such as extrusion, high temperature, overcharging, and short circuits during long-term use and storage, which can cause combustion and even explosion. However, lithium battery fires are difficult to extinguish for the following reasons: after a battery fire occurs, the temperature is very high; thermal runaway propagates quickly after combustion, easily igniting adjacent batteries and other combustible materials, causing subsequent combustion and even explosion; after the open flame of a lithium battery is extinguished, chemical reactions will continue to occur inside the battery to generate flammable gases, requiring measures to continue cooling and suppressing the continued reaction within the battery to prevent re-ignition; and there is a lack of specialized fire extinguishing agents with excellent comprehensive performance.

[0003] In the last century, people mostly used halon fire extinguishing agents to extinguish lithium battery fires. However, after long-term use, it was found that halon fire extinguishing agents had limited fire extinguishing capabilities for lithium battery fires. After extinguishing the open flame, it could not continue to effectively cool down the battery, and the battery could still reignite. In addition, the bromine and chlorine produced by halon fire extinguishing agents would destroy the atmospheric ozone layer, thereby affecting the entire ecological environment and threatening human survival.

[0004] Halon alternatives currently attracting researchers' attention include hydrogels, perfluorohexanone, dry water, and gaseous fire extinguishing agents. Hydrogels are highly hydrophilic, three-dimensional grid structures that can encapsulate lithium batteries. While the internal moisture absorbs heat and cools the battery, they also isolate oxygen and form a protective film to prevent re-ignition. However, after extinguishing a fire, the battery's outer shell becomes covered with a gelatinous substance, making it difficult to clean. Furthermore, the protective film is ineffective, prone to holes and the risk of further re-ignition. Perfluorohexanone is a new-generation halon alternative with low environmental impact, excellent fire suppression, and excellent insulation. It is liquid at room temperature, making it easy to store. However, at low concentrations, it can promote fire growth and is somewhat toxic. Furthermore, it poorly transfers the energy generated by thermal runaway, making it susceptible to re-ignition. Dry water fire extinguishing agents differ from traditional dry powder and water mist fire extinguishing agents in that they combine the advantages of both. They can effectively slow the temperature increase of unexploded lithium batteries and gradually lower their temperature, thereby inhibiting their internal chemical reactions and interrupting the thermal runaway transmission chain of lithium batteries. However, they have little effect on already-exploded lithium batteries and are unable to effectively suppress the battery fire. Furthermore, they have poor water retention and fluidity. Gaseous fire extinguishing agents, primarily inert gas fire extinguishing agents and halogenated hydrocarbon fire extinguishers, are non-decomposable, non-toxic, and clean. They have a good suppressive effect on the initial self-heating stage of battery fires. However, they are expensive, have high concentrations during the fire extinguishing process, are time-consuming, and cannot effectively and quickly suppress flames. In particular, they are less effective in suppressing the rapid combustion and explosion stage caused by thermal runaway in the later stages.

[0005] Invention patent CN202310102662.9 discloses a composite coated fire extinguishing agent for lithium batteries, comprising fluorocarbon fire extinguishing material microcapsules (with a core of fluorocarbon fire extinguishing material and a shell of polymer coating material), dry water material (with a core of water and a shell of hydrophobic gas-phase SiO2), and hydrogel. The agent has excellent fire suppression effect, high utilization rate, low cost, and high safety factor. However, the fluorocarbon fire extinguishing material in the agent contains fluorine, which has certain toxicity and a certain risk of thermal runaway. Invention patent CN202010619601.6 discloses a method for preparing a multi-stage water-sustaining bentonite fire extinguishing agent for lithium-ion batteries. The agent effectively coats bentonite containing stable bound water with a water-soluble polymer and an inorganic powder to form water-containing suspended microspheres, which are then assisted by a dispersing agent. The agent has a long-lasting cooling and fire extinguishing effect, can effectively prevent secondary reignition, and achieve safe and effective fire extinguishing of lithium batteries. However, the water content in the agent is low, and the initial cooling rate is poor. Summary of the Invention

[0006] The main purpose of the present invention is to provide a special fire extinguishing agent for lithium batteries, which has environmentally friendly raw materials, low cost, excellent insulation, good fire extinguishing and cooling effect, fast cooling rate, can effectively and quickly suppress flames, prevent thermal runaway of lithium batteries, has strong resistance to re-ignition, and has high utilization rate.

[0007] In order to achieve the purpose of the present invention, the present invention provides a special fire extinguishing agent for lithium batteries, comprising the following components in parts by weight: 15-25 parts of organic modified bentonite, 30-40 parts of polymer microspheres, 5-8 parts of composite flame retardant, 2-4 parts of surfactant, and 80-100 parts of hydrogel;

[0008] The polymer microspheres include a core material and a shell. The core material is 2-acrylamide-2-methylpropane sulfonate and silane-modified porous calcium carbonate, and the shell is an acrylic ester copolymer.

[0009] Furthermore, the preparation method of the polymer microspheres includes:

[0010] P1. Add 10-20wt% acetic acid to the porous calcium carbonate, stir evenly, add silane hydrolyzate, ultrasonicate at 80°C for 30-60min, filter, wash repeatedly with deionized water, and dry to obtain silane-modified porous calcium carbonate;

[0011] P2. Add an appropriate amount of deionized water to 2-acrylamido-2-methylpropanesulfonate and mix well. Then add the silane-modified porous calcium carbonate and ultrasonicate at 40-50°C for 30 minutes and dry to obtain a core material.

[0012] P3. Add an appropriate amount of acetone to the acrylic ester copolymer and ultrasonicate for 30 minutes, then add 40wt% ethanol solution and stir evenly, then add the above core material, stir at 70-80℃ for 1-2 hours, filter, dry, and crush to obtain polymer microspheres.

[0013] Furthermore, the silane hydrolyzate is composed of an aminosilane coupling agent, water, and ethanol in a mass ratio of 1:2:4;

[0014] The mass ratio of the porous calcium carbonate to the aminosilane coupling agent is 1:(0.05-0.09);

[0015] The mass ratio of the porous calcium carbonate to the 2-acrylamido-2-methylpropanesulfonate is 1:(0.3-0.6);

[0016] The added amount of the acrylic ester copolymer is 10-15% of the total mass of the porous calcium carbonate and the 2-acrylamido-2-methylpropanesulfonate.

[0017] The polymer microspheres of the present invention are coated with 2-acrylamido-2-methylpropane sulfonate and silane-modified porous calcium carbonate via an acrylate copolymer, so that the polymer microspheres release 2-acrylamido-2-methylpropane sulfonate and silane-modified porous calcium carbonate in the fire area. Simultaneously, the acrylate copolymer foams and expands at high temperature and adheres to the fire surface of the battery together with the core material, thereby isolating oxygen. The silane-modified porous calcium carbonate can adsorb combustion products and harmful gases, isolate oxygen, improve fire extinguishing efficiency, and further prevent thermal runaway of the lithium battery and reignition. The addition of 2-acrylamido-2-methylpropane sulfonate can improve the adhesion of the porous calcium carbonate to the battery surface and provide active groups to combine with free radicals generated by battery combustion, effectively suppressing thermal runaway of the lithium battery in the later stage, preventing reignition, and improving the fire extinguishing efficiency of the present invention.

[0018] Furthermore, the preparation method of the organic modified bentonite is as follows: sodium bentonite is acidified, filtered, dried, and calcined to obtain pretreated bentonite; an appropriate amount of deionized water is added to the pretreated bentonite and mixed evenly, and then imidazoline quaternary ammonium salt is added, the pH value is adjusted to 8, the temperature is raised to 60-70°C, stirred for 2-3 hours, centrifuged, dried, and ground to obtain the organic modified bentonite.

[0019] The present invention uses imidazoline quaternary ammonium salt to modify sodium bentonite, thereby improving the bonding strength between the sodium bentonite and the hydrogel. Furthermore, the sodium bentonite and the hydrogel can be covered on the surface of the lithium battery, thereby increasing the coverage area and coverage density of the protective layer, preventing the formation of pores, and improving the oxygen isolation effect of the present invention. Furthermore, after the fire is extinguished, the residue covering the battery surface is easily removed, thereby reducing processing costs. Furthermore, the addition of the imidazoline quaternary ammonium salt and the sodium bentonite increases the adsorption rate of battery combustion products, further suppressing thermal runaway in the later stage of the lithium battery, preventing re-ignition, and improving the utilization rate of the fire extinguishing agent and the fire extinguishing effect.

[0020] Furthermore, the addition amount of the imidazoline quaternary ammonium salt is 12-16% of the mass of the sodium bentonite.

[0021] Furthermore, the composite flame retardant is composed of aluminum hypophosphite, ammonium pentaborate, and ammonium polyphosphate in a mass ratio of 3:1:1. The present invention utilizes a composite flame retardant composed of aluminum hypophosphite, ammonium pentaborate, and ammonium polyphosphate in appropriate proportions. The three interact to enhance the fire extinguishing effect and cooling rate of the present invention, significantly suppress thermal runaway in lithium batteries, and prevent secondary re-ignition of lithium batteries.

[0022] Furthermore, the surfactant is any one or more of sodium secondary alkyl sulfonate, sodium dodecylbenzene sulfonate, polyoxyethylene fatty acid ester, fatty alcohol polyoxyethylene ether phosphate, and sodium lauryl sulfate.

[0023] Furthermore, the hydrogel is composed of the following raw materials in weight fractions: 20-30 parts of polyethylene glycol, 3-5 parts of low molecular weight sodium polyacrylate, 0.1-2 parts of super absorbent resin and 100-150 parts of deionized water.

[0024] The addition of polyethylene glycol and low-molecular-weight sodium polyacrylate to the hydrogel of the present invention not only increases the initial cooling rate of the fire extinguishing agent, but also allows the hydrogel to be evenly dispersed on the surface of the lithium battery fire extinguishing protective layer (i.e., a protective layer covering the battery surface formed during the fire extinguishing process using polymer microspheres, organically modified bentonite, etc.), thereby improving the heat insulation and cooling effect of the present invention.

[0025] Furthermore, the super absorbent resin is any one or more of sodium polyacrylate, polyacrylamide, carboxymethyl cellulose, sodium acrylate-butyl acrylate copolymer, and high molecular water-absorbing resin SAP.

[0026] The present invention also provides a method for preparing a special fire extinguishing agent for lithium batteries, which specifically comprises the following steps: adding polymer microspheres, a composite flame retardant and a surfactant into a reactor and mixing and stirring for 10-15 minutes; then adding organic modified bentonite and hydrogel and stirring for 5-10 minutes to obtain the special fire extinguishing agent for lithium batteries.

[0027] The present invention has achieved the following beneficial effects:

[0028] 1. The fire extinguishing agent of the present invention is a composite system formed by organically modified bentonite, polymer microspheres, a composite flame retardant, a hydrogel, and a surfactant. The organically modified bentonite, polymer microspheres, and hydrogel are used to synergistically extinguish fires. This allows the fire extinguishing agent of the present invention to respond quickly, rapidly extinguishing the fire and rapidly reducing the temperature in the early stages of a fire. Simultaneously, it can continuously reduce the temperature for a long period of time, absorbing heat and forming a tight protective layer on the surface of the lithium battery, isolating oxygen and suppressing the temperature rise and re-ignition caused by thermal runaway within the lithium battery. In the early stages of a fire, the hydrogel has a fast response speed, rapidly extinguishing the fire, and continuously absorbing heat to suppress the temperature rise caused by thermal runaway within the lithium battery. When heated, the polymer microspheres rupture their foamed shells, releasing the core material within and adhering to the surface of the lithium battery. This foaming shell not only absorbs harmful gases released by the lithium battery combustion but also combines with free radicals released during the battery combustion process, terminating the chain reaction. This synergistic fire extinguishing effect with the hydrogel improves the fire extinguishing efficiency of the present invention. The addition of organically modified bentonite forms a coating on the lithium battery surface, isolating it from oxygen and further preventing thermal runaway. This increases the coverage area and thickness of the present invention, improving the fire extinguishing speed. The addition of a composite flame retardant forms a porous char layer, which retards the escape of combustion gases and the spread of flames, delaying thermal runaway and reducing temperatures, thus enhancing the fire extinguishing effectiveness of the present invention.

[0029] 2. The raw materials of the fire extinguishing agent of the present invention are environmentally friendly, insulating, and non-corrosive, and will not cause damage to lithium batteries and their equipment, thereby ensuring the safety of the environment and equipment.

[0030] 3. The fire extinguishing agent of the present invention has a simple processing technology, and the components interact with each other, having the dual functions of cooling and extinguishing fires. It can not only quickly reduce the battery temperature, but also suppress secondary fires of lithium batteries. At the same time, the fire extinguishing agent is convenient to store and transport, and is suitable for solving the fire safety problems in the large-scale use of lithium-ion batteries. DETAILED DESCRIPTION

[0031] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0032] The special fire extinguishing agent for lithium batteries of the present invention is described below with reference to specific embodiments.

[0033] Example 1

[0034] A preparation method of a special fire extinguishing agent for lithium batteries comprises the following steps: adding 30 parts by mass of polymer microspheres, 5 parts of composite flame retardant and 2 parts of surfactant into a reactor, mixing and stirring for 15 minutes, then adding 15 parts of organic modified bentonite and 80 parts of hydrogel, and stirring for 8 minutes to obtain the special fire extinguishing agent for lithium batteries.

[0035] The preparation method of the above polymer microspheres is:

[0036] P1. 60 mL of 20 wt% acetic acid was added to 100 g of porous calcium carbonate and stirred thoroughly. Then, 63 g of silane hydrolyzate was added and ultrasonicated at 80°C for 40 minutes. The mixture was filtered, washed repeatedly with deionized water, and dried at 100°C for 3 hours to obtain silane-modified porous calcium carbonate. The silane hydrolyzate was composed of KH550 (γ-aminopropyltriethoxysilane), water, and ethanol in a mass ratio of 1:2:4.

[0037] P2. Add 50 mL of deionized water to 60 g of 2-acrylamido-2-methylpropanesulfonate (AMPS) and mix thoroughly. Then add the above-mentioned silane-modified porous calcium carbonate. Ultrasonicate at 50°C for 30 minutes and dry at 100°C for 2 hours to obtain the core material.

[0038] P3. Add 15 mL of acetone to 24 g of an acrylic acid ester copolymer and sonicate for 30 minutes. Then, add 20 mL of a 40 wt% ethanol solution and stir until uniform. Add the core material and stir at 80°C for 2 hours. Filter, dry, and crush through a 200 mesh sieve to obtain polymer microspheres. Preferably, the acrylic acid ester copolymer is ethylene-methyl acrylate copolymer (EMA).

[0039] The composite flame retardant is composed of aluminum hypophosphite, ammonium pentaborate and ammonium polyphosphate in a mass ratio of 3:1:1.

[0040] The surfactant is sodium dodecylbenzenesulfonate.

[0041] The organically modified bentonite is prepared by treating 1 kg of sodium bentonite with 2 mol / L hydrochloric acid for 4 hours, filtering, drying, and calcining to obtain pretreated bentonite. 100 mL of deionized water is added to the pretreated bentonite and mixed thoroughly. Then, 160 g of an imidazoline quaternary ammonium salt is added, the pH is adjusted to 8 with a 2 mol / L NaOH solution, the mixture is heated to 60°C, stirred for 3 hours, centrifuged, dried, ground, and sieved through 200 mesh to obtain the organically modified bentonite. The imidazoline quaternary ammonium salt is selected from Green Union Chemical, model YTY-05, and the sodium bentonite is 325 mesh.

[0042] The hydrogel is composed of the following raw materials by weight: 30 parts polyethylene glycol, 4 parts low-molecular-weight sodium polyacrylate, 0.1 parts superabsorbent resin, and 100 parts deionized water. The low-molecular-weight sodium polyacrylate is Derin 42N, a Derin new material; and the superabsorbent resin is a high-molecular-weight water-absorbing resin (SAP).

[0043] Example 2

[0044] A preparation method of a special fire extinguishing agent for lithium batteries comprises the following steps: adding 40 parts by mass of polymer microspheres, 8 parts of composite flame retardant and 4 parts of surfactant into a reactor, mixing and stirring for 15 minutes, then adding 25 parts of organic modified bentonite and 100 parts of hydrogel, and stirring for 10 minutes to obtain the special fire extinguishing agent for lithium batteries.

[0045] The preparation method of the above polymer microspheres is:

[0046] P1. 60 mL of 20 wt% acetic acid was added to 100 g of porous calcium carbonate and stirred thoroughly. Then, 35 g of silane hydrolyzate was added and ultrasonicated at 80°C for 40 minutes. The mixture was filtered, washed repeatedly with deionized water, and dried at 100°C for 3 hours to obtain silane-modified porous calcium carbonate. The silane hydrolyzate was composed of KH550, water, and ethanol in a mass ratio of 1:2:4.

[0047] P2. Add 20 mL of deionized water to 30 g of 2-acrylamido-2-methylpropanesulfonate (AMPS) and mix thoroughly. Then add the above-mentioned silane-modified porous calcium carbonate. Ultrasonicate at 50°C for 30 minutes and dry at 100°C for 2 hours to obtain the core material.

[0048] P3. Add 8 mL of acetone to 13 g of EMA and sonicate for 30 min. Then add 10 mL of 40 wt% ethanol solution and stir evenly. Then add the above-mentioned core material and stir at 80°C for 2 h. Filter, dry, crush and sieve 200 mesh to obtain polymer microspheres.

[0049] The composite flame retardant is the same as that in Example 1, refer to Example 1.

[0050] The above surfactant is polyoxyethylene fatty acid ester.

[0051] The organic modified bentonite is prepared by treating 1 kg of sodium bentonite (325 mesh) with 2 mol / L hydrochloric acid for 4 hours, filtering, drying, and calcining to obtain pretreated bentonite; adding 100 mL of deionized water to the pretreated bentonite and mixing uniformly; then adding 120 g of imidazoline quaternary ammonium salt YTY-05; adjusting the pH to 8 with 2 mol / L NaOH solution; heating to 60° C., stirring for 3 hours, centrifuging, drying, grinding, and sieving through 200 mesh to obtain the organic modified bentonite.

[0052] The hydrogel is composed of the following raw materials in weight fractions: 20 parts of polyethylene glycol, 5 parts of low molecular weight sodium polyacrylate Derin 42N, 0.4 parts of super absorbent resin, and 150 parts of deionized water.

[0053] Example 3

[0054] A preparation method of a special fire extinguishing agent for lithium batteries comprises the following steps: adding 36 parts by mass of polymer microspheres, 6 parts of composite flame retardant and 3 parts of surfactant into a reactor, mixing and stirring for 15 minutes, then adding 22 parts of organic modified bentonite and 100 parts of hydrogel, and stirring for 10 minutes to obtain the special fire extinguishing agent for lithium batteries.

[0055] The preparation method of the above polymer microspheres is:

[0056] P1. 60 mL of 20 wt% acetic acid was added to 100 g of porous calcium carbonate and stirred thoroughly. Then, 56 g of silane hydrolyzate was added and ultrasonicated at 80°C for 40 minutes. The mixture was filtered, washed repeatedly with deionized water, and dried at 100°C for 3 hours to obtain silane-modified porous calcium carbonate. The silane hydrolyzate was composed of KH550, water, and ethanol in a mass ratio of 1:2:4.

[0057] P2. Add 35 mL of deionized water to 40 g of 2-acrylamido-2-methylpropanesulfonate (AMPS) and mix thoroughly. Then add the above-mentioned silane-modified porous calcium carbonate. Ultrasonicate at 50°C for 30 minutes and dry at 100°C for 2 hours to obtain the core material.

[0058] P3. Add 10 mL of acetone to 15 g of EMA and sonicate for 30 minutes. Then add 12 mL of 40 wt% ethanol solution and stir evenly. Then add the above-mentioned core material and stir at 80°C for 2 hours. Filter, dry, crush and sieve 200 mesh to obtain polymer microspheres.

[0059] The composite flame retardant and surfactant are the same as those in Example 1, refer to Example 1.

[0060] The organic modified bentonite is prepared by treating 1 kg of sodium bentonite (325 mesh) with 2 mol / L hydrochloric acid for 4 hours, filtering, drying, and calcining to obtain pretreated bentonite; adding 100 mL of deionized water to the pretreated bentonite and mixing uniformly; then adding 150 g of imidazoline quaternary ammonium salt YTY-05; adjusting the pH to 8 with 2 mol / L NaOH solution; heating to 60° C., stirring for 3 hours, centrifuging, drying, grinding, and sieving through 200 mesh to obtain the organic modified bentonite.

[0061] The hydrogel is composed of the following raw materials in weight fractions: 25 parts of polyethylene glycol, 4 parts of low molecular weight sodium polyacrylate Derin 42N, 0.2 parts of super absorbent resin, and 150 parts of deionized water. The super absorbent resin is polyacrylamide.

[0062] Example 4

[0063] The raw materials and preparation method of a fire extinguishing agent for lithium batteries are the same as those in Example 3. The difference is that the preparation method of the polymer microspheres in Example 4 is:

[0064] P1. 60 mL of 20 wt% acetic acid was added to 100 g of porous calcium carbonate and stirred thoroughly. Then, 56 g of silane hydrolyzate was added and ultrasonicated at 80°C for 40 minutes. The mixture was filtered, washed repeatedly with deionized water, and dried at 100°C for 3 hours to obtain silane-modified porous calcium carbonate. The silane hydrolyzate was composed of KH550, water, and ethanol in a mass ratio of 1:2:4.

[0065] P2. Add 40 mL of deionized water to 50 g of 2-acrylamido-2-methylpropanesulfonate (AMPS) and mix thoroughly. Then add the above-mentioned silane-modified porous calcium carbonate. Ultrasonicate at 50°C for 30 minutes and dry at 100°C for 2 hours to obtain the core material.

[0066] P3. Add 13 mL of acetone to 22 g of EMA and sonicate for 30 minutes. Then add 18 mL of 40 wt% ethanol solution and stir evenly. Then add the above-mentioned core material, stir at 80°C for 2 hours, filter, dry, crush and sieve 200 mesh to obtain polymer microspheres.

[0067] Comparative Example 1

[0068] The raw materials, preparation method, etc. of the lithium battery-specific fire extinguishing agent in Comparative Example 1 are the same as those in Example 4, except that no organic modified bentonite is added in Comparative Example 1.

[0069] Comparative Example 2

[0070] The raw materials, preparation method, etc. of the special fire extinguishing agent for lithium batteries in Comparative Example 2 are the same as those in Example 4. The difference is that pretreated bentonite is used in place of organic modified bentonite in Comparative Example 2, and the addition amount is still 22 parts.

[0071] Comparative Example 3

[0072] The raw materials and preparation method of the lithium battery-specific fire extinguishing agent in Comparative Example 3 are the same as those in Example 4, except that polymer microspheres are not added in Comparative Example 3.

[0073] Comparative Example 4

[0074] The raw materials, preparation method, etc. of the lithium battery-specific fire extinguishing agent in Comparative Example 4 are the same as those in Example 4. The difference is that in Comparative Example 4, no polymer microspheres are added, and only a mixture of porous calcium carbonate, AMPS, and EMA in a mass ratio of 50:25:11 is added, and the amount of the mixture added is still 36 parts.

[0075] Comparative Example 5

[0076] The raw materials, preparation method, etc. of the lithium battery-specific fire extinguishing agent in Comparative Example 5 are the same as those in Example 5. The difference is that AMPS is not added to the polymer microsphere core material in Comparative Example 5, that is, EMA is directly wrapped with silane-modified porous calcium carbonate, and the added amount is still 36 parts.

[0077] Comparative Example 6

[0078] The raw materials, preparation method, etc. of the lithium battery-specific fire extinguishing agent in Comparative Example 6 are the same as those in Example 6, except that the polymer microspheres in Comparative Example 6 do not have an EMA shell, and the added amount is still 36 parts.

[0079] Comparative Example 7

[0080] The raw materials, preparation method, etc. of the lithium battery-specific fire extinguishing agent of Comparative Example 7 are the same as those of Example 7, except that polyethylene glycol is not added to the hydrogel of Comparative Example 7.

[0081] Comparative Example 8

[0082] The raw materials, preparation method, etc. of the lithium battery-specific fire extinguishing agent of Comparative Example 8 are the same as those of Example 8, except that low molecular weight sodium polyacrylate is not added to the hydrogel of Comparative Example 8.

[0083] The fire extinguishing performance and anti-reignition performance of the lithium battery fire extinguishing agents prepared in Examples 1-4 and Comparative Examples 1-8 were tested, and the test results are shown in Table 1 below.

[0084] Fire extinguishing performance test: Spray the fire of the lithium battery of the electric vehicle using three 3.7V batteries. The spraying distance does not exceed 700mm and the spraying time interval is 1-2s. After the open flame is extinguished, observe for 1 hour to see if there is any possibility of re-ignition.

[0085] Table 1 Fire extinguishing performance test results of lithium battery special fire extinguishing agent

[0086]

[0087]

[0088] From the test results in Table 1 above, it can be seen that the fire extinguishing agent for lithium batteries of the present invention has a fast fire extinguishing rate and will not re-ignite. From the comparative data of Comparative Example 3 and Example 4, it can be seen that the addition of polymer microspheres significantly improves the fire extinguishing effect of the fire extinguishing agent of the present invention and suppresses the possibility of re-ignition of lithium batteries.

[0089] The technical features of the above embodiments can be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0090] The above embodiments merely illustrate several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the scope of the present invention, all of which fall within the scope of protection of the present invention.

Claims

1. A fire extinguishing agent for lithium batteries, characterized in that: The invention comprises the following components in parts by weight: 15-25 parts of organic modified bentonite, 30-40 parts of polymer microspheres, 5-8 parts of composite flame retardant, 2-4 parts of surfactant, and 80-100 parts of hydrogel; The polymer microspheres include a core material and a shell. The core material is 2-acrylamide-2-methylpropane sulfonate and silane-modified porous calcium carbonate, and the shell is an acrylic ester copolymer.

2. The lithium battery-specific fire extinguishing agent according to claim 1, characterized in that: The preparation method of the polymer microspheres comprises: P1. Add 10-20wt% acetic acid to the porous calcium carbonate, stir evenly, add silane hydrolyzate, ultrasonicate at 80°C for 30-60min, filter, wash repeatedly with deionized water, and dry to obtain silane-modified porous calcium carbonate; P2. Add an appropriate amount of deionized water to 2-acrylamido-2-methylpropanesulfonate and mix well. Then add the silane-modified porous calcium carbonate and ultrasonicate at 40-50°C for 30 minutes and dry to obtain a core material. P3. Add an appropriate amount of acetone to the acrylic ester copolymer and ultrasonicate for 30 minutes, then add 40wt% ethanol solution and stir evenly, then add the above core material, stir at 70-80℃ for 1-2 hours, filter, dry, and crush to obtain polymer microspheres.

3. The lithium battery-specific fire extinguishing agent according to claim 2, characterized in that: The silane hydrolyzate is composed of an aminosilane coupling agent, water and ethanol in a mass ratio of 1:2:4; The mass ratio of the porous calcium carbonate to the aminosilane coupling agent is 1:(0.05-0.09); The mass ratio of the porous calcium carbonate to the 2-acrylamido-2-methylpropanesulfonate is 1:(0.3-0.6); The added amount of the acrylic ester copolymer is 10-15% of the total mass of the porous calcium carbonate and the 2-acrylamido-2-methylpropane sulfonate.

4. The lithium battery-specific fire extinguishing agent according to claim 1, characterized in that: The preparation method of the organic modified bentonite comprises: acidifying sodium bentonite, filtering, drying, and calcining to obtain pretreated bentonite; adding an appropriate amount of deionized water to the pretreated bentonite and mixing uniformly; then adding imidazoline quaternary ammonium salt, adjusting the pH value to 8, heating to 60-70°C, stirring for 2-3 hours, centrifuging, drying, and grinding to obtain the organic modified bentonite.

5. The lithium battery-specific fire extinguishing agent according to claim 4, characterized in that: The added amount of the imidazoline quaternary ammonium salt is 12-16% of the mass of the sodium bentonite.

6. The lithium battery-specific fire extinguishing agent according to claim 1, characterized in that: The composite flame retardant is composed of aluminum hypophosphite, ammonium pentaborate and ammonium polyphosphate in a mass ratio of 3:1:

1.

7. The lithium battery-specific fire extinguishing agent according to claim 1, characterized in that: The surfactant is any one or more of sodium secondary alkyl sulfonate, sodium dodecylbenzene sulfonate, polyoxyethylene fatty acid ester, fatty alcohol polyoxyethylene ether phosphate, and sodium lauryl sulfate.

8. The fire extinguishing agent for lithium batteries according to claim 1, characterized in that: The hydrogel is composed of the following raw materials in weight fractions: 20-30 parts of polyethylene glycol, 3-5 parts of low-molecular-weight sodium polyacrylate, 0.1-2 parts of highly absorbent resin and 100-150 parts of deionized water.

9. The fire extinguishing agent for lithium batteries according to claim 1, characterized in that: The super absorbent resin is any one or more of sodium polyacrylate, polyacrylamide, carboxymethyl cellulose, sodium acrylate-butyl acrylate copolymer, and high molecular water-absorbing resin SAP.

10. A method for preparing a fire extinguishing agent for lithium batteries according to any one of claims 1 to 9, characterized in that: The specific steps are: adding polymer microspheres, composite flame retardant and surfactant into a reaction kettle and mixing and stirring for 10-15 minutes, then adding organic modified bentonite and hydrogel and stirring for 5-10 minutes to obtain the lithium battery special fire extinguishing agent.

Images