Aerogel fire extinguishing agent and method of making same

Abstract

The application discloses an aerogel fire extinguishing agent and a preparation method thereof. The aerogel fire extinguishing agent is prepared from the following raw materials by simple mixing and hydrothermal reaction, and then the solid product after the hydrothermal reaction is subjected to CO2 supercritical drying: 10-30 parts of graphene aerogel powder, 1-5 parts of Mg(HCO3)2 powder, 0.1-0.5 parts of inorganic fiber, 0.01-0.1 parts of sodium dodecyl sulfonate and 50-100 parts of water. The inorganic fiber is combined with the layered porous graphene aerogel to form a stable product structure, the magnesium bicarbonate is effectively dispersed on the surface of the graphene and in the graphene aerogel, and the fire extinguishing substance is gradually released along with the progress of the fire extinguishing process, so that the rekindling is effectively prevented. The specific structure is constructed to synergistically combine the simple raw materials, so that the prepared fire extinguishing agent has the excellent characteristics of rapid cooling, non-rekindling, environmental friendliness, high-efficiency toxic gas adsorption and the like, the fire extinguishing efficiency is higher, the ignition prevention effect is better, the battery combustion fire can be effectively extinguished, and the application value is extremely high.

Description

Technical Field

[0001] This invention belongs to the field of aerogel technology and relates to an aerogel fire extinguishing agent and its preparation method. Specifically, it relates to an aerogel fire extinguishing agent that can be used for lithium battery fire extinguishing and its preparation method. Background Technology

[0002] Lithium-ion batteries have been widely used in urban underground spaces due to their high energy density, good cycle performance, and portability. However, lithium-ion batteries themselves pose a high fire hazard. Under conditions such as heating by external heat sources, compression and puncture under external forces, or external short circuits, uncontrolled chain reactions can occur inside the battery, leading to thermal runaway. This not only ignites surrounding combustibles and burns nearby equipment, but the toxic and harmful fumes and gases produced by the battery combustion also threaten human life and health, causing irreparable loss of life and property.

[0003] Therefore, it is necessary to find an ideal fire extinguishing agent that can not only extinguish the fire but also prevent the battery temperature from rising. Commonly used fire extinguishing agents for lithium-ion battery fires include water-based fire extinguishing agents, foam fire extinguishing agents, dry powder fire extinguishing agents, CO2 fire extinguishing agents, and halon fire extinguishing agents. These fire extinguishing agents can extinguish the open flames of lithium-ion batteries, but they cannot effectively stop the internal chemical reactions of the battery. The high internal temperature of the battery can still support the internal chemical reactions, and there is a possibility of secondary reignition of the extinguished lithium battery.

[0004] Aerogel is a three-dimensional nanoporous material with ultra-high porosity. It is a highly dispersed solid nanomaterial composed of aggregated polymer or colloidal particles, possessing a nanoporous network structure. The gaseous dispersion medium filling its nanopores endows aerogels with advantages such as low density and low thermal conductivity. It is widely used in numerous fields including military, construction, energy, and environmental protection, serving as a novel heat insulation and fire extinguishing material. Through its unique properties, aerogel can exhibit excellent fire extinguishing effects in various complex fire scenarios. For example, in electronic equipment fires, the microporous structure of aerogel can adsorb combustion products, effectively inhibiting fire spread and protecting the safe operation of equipment. In building fires, aerogel extinguishing agents can form an insulating layer and effectively reduce temperature, controlling the fire. In oil and gas fires, aerogel extinguishing agents can form an inert gas layer and reduce the temperature of the fire source, effectively controlling the spread of oil and gas fires and reducing the risk of secondary explosions. Aerogel extinguishing agents have a wide range of applications, effectively responding to various complex fires, exhibiting excellent fire extinguishing effects, protecting property, reducing casualties, and mitigating the environmental impact of fire accidents. The gel materials in aerogel fire extinguishing agents are mainly divided into two categories: inorganic gels and organic polymer gels. Inorganic aerogels are prone to water loss, shrinkage, cracking, and powdering after gelation, resulting in poor mechanical properties. Organic aerogels are flammable and have higher costs. CN117414559A discloses an aerogel foam fire extinguishing agent and its in-situ preparation method. First, a template agent is added to an ammonia-ethanol mixed solution and heated to dissolve. Then, tetraethyl orthosilicate is added, and hydrolysis and condensation are performed under heating conditions to produce aerogel particles. Next, a compound surfactant is added for surface adsorption modification and steric stabilization. Finally, fire extinguishing components are added to obtain the aerogel foam fire extinguishing agent. CN117398649A discloses an aerogel fire extinguishing material based on a surfactant binary compound system and its preparation method. This fire extinguishing material is composed of silica aerogel powder, surfactant, composite colloid, foam stabilizer, antifreeze agent, crosslinking agent, fire extinguishing component, and water. It uniformly disperses solid silica nanoporous material in a liquid fire extinguishing agent, forming a structurally stable aerogel fire extinguishing agent. During fire extinguishing, the silica aerogel powder and the fire extinguishing enhancer component interact to form a nanopolymerized aerogel fire extinguishing material. CN116785637A discloses a high-efficiency aerogel fire extinguishing agent and its preparation method, using inorganic non-metallic oxide sol, perfluorohexanone, flame retardant, and foaming agent as raw materials. Perfluorohexanone is encapsulated in the nanoporous structure of the sol, effectively solving the problem of perfluorohexanone's low boiling point and high volatility. By leveraging the synergistic effect of the organic fire extinguishing agent perfluorohexanone and the inorganic fire extinguishing agent aerogel, the advantages of perfluorohexanone's high fire extinguishing performance and pollution-free nature, as well as the high specific surface area and porosity of aerogel, are integrated, resulting in a fire extinguishing agent with excellent characteristics such as rapid cooling, non-reignition, environmental friendliness, and efficient adsorption of toxic gases.CN106310577A discloses a high-efficiency liquid fire extinguishing agent containing aerogel material, comprising aerogel powder, water, surfactant, fire extinguishing enhancer, stabilizer, and other components. When aerogel powder is applied to the fire extinguishing agent, the aerogel powder and fire extinguishing enhancer interact during fire extinguishing, effectively covering the substrate surface and blocking heat transfer, preventing the spread of flames and heat. CN110448850A discloses a low-temperature concentrated fire extinguishing agent and its preparation and application methods, comprising the following components in parts by weight: 7-13 parts diethylene glycol, 25-35 parts ethylene glycol, 15-25 parts inorganic salt, 2-4 parts foaming agent, 2-4 parts fluorocarbon surfactant, 3-7 parts flame retardant, and 28-36 parts distilled water. Because this invention uses ethylene glycol to lower the freezing point of the fire extinguishing agent, it has a lower freezing point, making it suitable for use in cold regions and expanding the application range of the fire extinguishing agent. It exhibits good fire extinguishing effects at both low and normal temperatures. CN112169241B discloses a water-based aerogel high-efficiency fire extinguishing agent and its preparation method. Using inorganic aerogel powder, template agent, phosphorus-containing flame retardant, nitrogen-containing flame retardant, and hydrophilic colloidal stabilizer as raw materials, the agent utilizes the ultra-low thermal conductivity and ultra-high adsorption capacity of inorganic nanoporous aerogel to significantly improve the efficiency of the fire extinguishing agent. Simultaneously, the phosphorus-containing and nitrogen-containing flame retardants are combined as relevant functional components of the fire extinguishing agent. Colloidal stabilizers and ion buffers are added to the water-based flame retardant, increasing its uniformity and shelf life. This results in an agent that possesses both high-efficiency fire extinguishing function and good fire prevention and flame retardant properties. CN111840880A discloses an aerogel fire extinguishing agent and its preparation method. This aerogel fire extinguishing agent comprises modified silica aerogel and silica sol. It is prepared by: dispersing silica aerogel evenly in a polyethyleneimine aqueous solution at pH=5 to obtain a modified silica aerogel solution; then adding silica sol and cellulose hydroxyethyl ether sequentially, and dispersing evenly. This fire extinguishing agent has higher fire extinguishing efficiency and better ignition prevention effect. CN111494863A discloses an aerogel fire extinguishing agent comprising 100-120 parts aerogel powder, 5-10 parts catalyst, 10-25 parts ethanol, 10-12 parts hydrochloric acid, 15-20 parts ammonia, 2-5 parts fire extinguishing enhancer, and 1-3 parts fire-resistant fiber. Doping with oxide particles such as copper oxide and iron oxide can increase the service temperature of aerogels. Coating the outer layer of aerogel composites with an infrared-blocking coating can better improve the infrared radiation blocking effect of aerogel composites, while also facilitating the bonding between fibers and aerogels and improving the mechanical properties of aerogel composites.

[0005] While the existing aerogel fire extinguishing agents described above have a certain fire extinguishing effect, their complex composition generally requires complex surfactants, flame retardants, foaming agents, etc., making the preparation process relatively cumbersome and complicated, which is not conducive to large-scale use. Therefore, to address the above-mentioned shortcomings of the existing technology, it is necessary to develop a novel aerogel fire extinguishing agent and its preparation method, which can achieve higher fire extinguishing efficiency, effective and rapid cooling, and suppression of reignition. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides an aerogel fire extinguishing agent and its preparation method. The aerogel fire extinguishing agent uses graphene aerogel, magnesium bicarbonate, inorganic fibers, sodium dodecyl sulfonate, and water as raw materials. These materials are simply mixed and then subjected to a hydrothermal reaction. The solid product from the hydrothermal reaction is then dried using supercritical CO2. The resulting fire extinguishing agent uses readily available and simple raw materials, exhibits good fire extinguishing effects, and can quickly and effectively suppress fires in single-cell lithium iron phosphate batteries. It can also effectively reduce the temperature of lithium batteries, effectively inhibit reignition, and prevent the spread of battery fires.

[0007] The purpose of this invention is to provide an aerogel fire extinguishing agent, which is prepared from the following raw materials in parts by weight:

[0008] 10-30 parts of graphene aerogel powder;

[0009] 1-5 parts of Mg(HCO3)2 powder;

[0010] Inorganic fibers: 0.1–0.5 parts;

[0011] Sodium dodecyl sulfonate 0.01–0.1 parts;

[0012] 50-100 parts water. The graphene aerogel powder was purchased from Beijing Beike New Material Technology Co., Ltd., and has a porous layered structure. The inorganic fibers are one or more of glass fibers, basalt fibers, and alumina fibers. The size of the inorganic fibers is not limited, but preferably, when the diameter of the inorganic fibers is 50-1000 nm and the length is 30-2000 μm, the resulting aerogel fire extinguishing agent has the best mechanical properties and high product stability. The inorganic fibers are tightly connected with the graphene aerogel, and the inorganic fibers are interwoven into a network, which can improve the mechanical properties of the material and the stability of the fire extinguishing agent material to a certain extent. Sodium bicarbonate is distributed in particulate form in the pores and surface of the aerogel particles. The aerogel also contains a large amount of carbon dioxide gas and a small amount of water. In the early stages of a fire, the water inside the graphene aerogel evaporates, absorbing heat and extinguishing the fire. Magnesium bicarbonate decomposes, absorbing heat and producing magnesium carbonate, water vapor, and carbon dioxide. Simultaneously, some carbon dioxide escapes from the aerogel, thus isolating oxygen and reducing the lithium battery temperature to some extent, inhibiting battery combustion. As the temperature continues to rise, the aerogel network is completely destroyed, and carbon dioxide continues to escape, isolating oxygen. Meanwhile, magnesium carbonate decomposes to produce magnesium oxide and carbon dioxide, collectively suppressing the fire. Furthermore, the aerogel fire extinguishing agent obtained in this application has good fluidity and viscosity, effectively adsorbing onto the lithium battery surface. Upon heating, it loses its fluidity. The graphene particles and the generated MgO and Mg(OH)2 particles are themselves fire-extinguishing and flame-retardant materials, adhering to the surface of the burning material, reducing its contact area with oxygen, isolating oxygen, preventing reignition, and further controlling the fire.

[0013] As a preferred embodiment, the fire extinguishing agent is prepared from the following raw materials in parts by weight:

[0014] 20 parts of graphene aerogel powder;

[0015] Two parts of Mg(HCO3)2 powder;

[0016] 0.2 parts of inorganic fiber;

[0017] Sodium dodecyl sulfonate 0.01 parts;

[0018] 50 parts water.

[0019] Another object of the present invention is to provide a method for preparing an aerogel fire extinguishing agent, comprising the following steps:

[0020] 1) Disperse 1 to 5 parts of Mg(HCO3)2 powder in 50 to 100 parts of water, stir until completely dissolved, and obtain magnesium bicarbonate solution;

[0021] 2) Add 0.01 to 0.1 parts of sodium dodecyl sulfonate and 0.1 to 0.5 parts of inorganic fiber to the magnesium bicarbonate solution in sequence, and continue stirring until the dispersion is uniform to obtain dispersion A; the presence of sodium dodecyl sulfonate serves as a dispersant to improve the dispersion and wetting of the raw materials in the system, and also facilitates the deposition and adhesion of magnesium bicarbonate inside and on the surface of the graphene aerogel.

[0022] 3) Add 10-30 parts of graphene aerogel powder to dispersion A, stir continuously until uniformly dispersed, transfer the dispersion product to a hydrothermal reactor with a polytetrafluoroethylene liner, seal, evacuate to a vacuum degree of 0.8, heat to 50-80℃ and react for 4 hours, cool to room temperature after the reaction is completed, and filter to obtain solid product A.

[0023] 4) Place solid product A in a CO2 supercritical high-pressure extraction device and perform supercritical drying for 3-5 hours at a temperature of 30-60℃ and a pressure of 5-10MPa using CO2 as the medium to obtain aerogel fire extinguishing agent.

[0024] Specifically, in step 3), the hydrothermal reaction is carried out at 60℃ for 4 hours, and the filtration is performed by vacuum filtration. In step 4), the CO2 supercritical high-pressure extraction is carried out with CO2 as the medium at a temperature of 50℃ and a pressure of 10MPa for 5 hours of supercritical drying.

[0025] The specific preparation method of this invention can obtain a high-performance aerogel fire extinguishing agent. Through hydrothermal reaction of a uniformly dispersed mixture, magnesium bicarbonate particles are evenly distributed within the pores and surface of the graphene aerogel. Simultaneously, the layered graphene aerogel particles adhere to each other, and the inorganic fibers interweave to form a network, creating disordered inorganic fiber reinforcing ribs within the layered graphene aerogel, thus improving the material's mechanical properties and enhancing the stability of the fire extinguishing agent structure. Supercritical carbon dioxide drying of the gel system after the hydrothermal reaction replaces most of the water within the gel with carbon dioxide, effectively improving the fire extinguishing effect of the agent.

[0026] The aerogel fire extinguishing agent obtained by this invention can quickly extinguish battery fires and effectively inhibit fire reignition. It can be widely used in fire control of batteries such as lithium batteries, zinc-manganese batteries, nickel-metal hydride batteries, fuel cells, zinc-air batteries, or nickel-cadmium batteries.

[0027] Compared with the prior art, the beneficial effects of the technical solution of this application are as follows:

[0028] 1. Aerogel fire extinguishing agent is prepared from graphene aerogel, magnesium bicarbonate, inorganic fiber, sodium dodecyl sulfonate and water. The composition of the fire extinguishing agent is simple, the raw materials are easy to obtain, and it does not use complex and flammable organic materials and phosphorus-containing flame retardants. The cost is low, the product pollution is small, and it has good economic value.

[0029] 2. When the aerogel fire extinguishing agent obtained by this invention is applied to a fire, the high specific heat capacity water first rapidly vaporizes, quickly carrying away heat and lowering the temperature of the affected area. A large amount of carbon dioxide is also gradually released, isolating oxygen. Simultaneously, the magnesium bicarbonate on the graphene surface and inside gradually absorbs heat and begins to decompose as the temperature rises. While cooling, the products also effectively inhibit combustion. Furthermore, the aerogel powder can effectively act on the burning battery; its high specific surface area and porosity effectively adsorb toxic gases and microparticles released from the burning battery. At the same time, the nano-scale graphene aerogel powder and the decomposition products of magnesium bicarbonate, MgO and Mg(OH)2, adhere to the surface of the burning material, reducing its contact area with oxygen and isolating oxygen to prevent reignition. Covering the battery surface effectively isolates air and prevents reignition. Under the synergistic effect of the components in the aerogel fire extinguishing agent of this invention, it can effectively extinguish battery fires, demonstrating extremely high application value.

[0030] 3. The aerogel fire extinguishing agent obtained in this invention combines inorganic fibers with layered porous graphene aerogel. The inorganic fibers intertwine to form a network, which is interwoven with the three-dimensional layered graphene to form a stable product structure. Simultaneously, the specific preparation method allows magnesium bicarbonate to be effectively dispersed on the graphene surface and inside the graphene aerogel. As the fire extinguishing process progresses, the extinguishing substance is gradually released, resulting in more effective prevention of reignition. Constructing a specific structure effectively utilizes the graphene aerogel, inorganic fibers, magnesium bicarbonate, and the water and carbon dioxide within the aerogel. Combining the advantages of the raw materials, the prepared fire extinguishing agent possesses excellent characteristics such as rapid cooling, prevention of reignition, environmental friendliness, and efficient adsorption of toxic gases, resulting in higher fire extinguishing efficiency and better prevention of ignition. Detailed Implementation

[0031] To make the technical problems solved by this invention, the technical solutions adopted, and the technical effects achieved clearer, the technical solutions of the embodiments of this invention will be described in further detail below. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0032] It should be noted that, in this document, the reference to "embodiment" means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. Those skilled in the art will explicitly and implicitly understand that the embodiments described herein can be combined with other embodiments.

[0033] Unless otherwise specified, the experimental methods used in the following examples are conventional methods. Unless otherwise specified, the materials and reagents used in the following examples are commercially available.

[0034] The following examples are merely intended to provide those skilled in the art with a complete disclosure and description of how to prepare and evaluate the compounds, compositions, articles, devices, and / or methods described in the claims and protected by this invention, and are intended to be exemplary only, and not to limit the scope of what the inventors consider their invention. Efforts have been made to ensure accuracy regarding figures (e.g., quantities, temperatures, etc.), but some errors and deviations should be taken into account.

[0035] Example 1

[0036] An aerogel fire extinguishing agent is prepared by the following method:

[0037] 1) Disperse 1 part of Mg(HCO3)2 powder in 50 parts of water and stir until completely dissolved to obtain a magnesium bicarbonate solution; 2) Add 0.01 parts of sodium dodecyl sulfonate and 0.1 parts of glass fiber with a diameter of 50-1000 nm and a length of 30-2000 μm to the magnesium bicarbonate solution in sequence, and continue stirring until uniformly dispersed to obtain dispersion A; 3) Add 10 parts of graphene aerogel powder to dispersion A, and continue stirring until uniformly dispersed. Transfer the dispersion product to a hydrothermal reactor lined with polytetrafluoroethylene, seal it, evacuate to a vacuum degree of 0.8, heat to 50℃ and react for 4 hours. After the reaction is completed, cool to room temperature and filter to obtain solid product A; 4) Place solid product A in a CO2 supercritical high-pressure extraction device and supercritically dry it for 3 hours at a temperature of 30℃ and a pressure of 5 MPa using CO2 as the medium to obtain the aerogel fire extinguishing agent.

[0038] Example 2

[0039] An aerogel fire extinguishing agent is prepared by the following method:

[0040] 1) Disperse 5 parts of Mg(HCO3)2 powder in 100 parts of water and stir until completely dissolved to obtain a magnesium bicarbonate solution; 2) Add 0.1 parts of sodium dodecyl sulfonate, 0.5 parts of a mixture of basalt fiber and alumina fiber with a diameter of 50-1000 nm and a length of 30-2000 μm in a mass ratio of 1:1 to the magnesium bicarbonate solution and continue stirring until uniformly dispersed to obtain dispersion A; 3) Add 30 parts of graphene aerogel powder to dispersion A and continue stirring until uniformly dispersed. Transfer the dispersion product to a hydrothermal reactor lined with polytetrafluoroethylene, seal it, evacuate to a vacuum degree of 0.8, heat to 80℃ and react for 4 hours. After the reaction is completed, cool to room temperature and filter to obtain solid product A; 4) Place solid product A in a CO2 supercritical high-pressure extraction device and supercritically dry it at a temperature of 60℃ and a pressure of 10 MPa for 5 hours using CO2 as the medium to obtain the aerogel fire extinguishing agent.

[0041] Example 3

[0042] An aerogel fire extinguishing agent is prepared by the following method:

[0043] 1) Disperse 2 parts of Mg(HCO3)2 powder in 50 parts of water and stir until completely dissolved to obtain a magnesium bicarbonate solution; 2) Add 0.01 parts of sodium dodecyl sulfonate and 0.2 parts of glass fiber with a diameter of 50-1000 nm and a length of 30-2000 μm to the magnesium bicarbonate solution in sequence, and continue stirring until uniformly dispersed to obtain dispersion A; 3) Add 20 parts of graphene aerogel powder to dispersion A, and continue stirring until uniformly dispersed. Transfer the dispersion product to a hydrothermal reactor lined with polytetrafluoroethylene, seal it, evacuate to a vacuum degree of 0.8, heat to 60℃ and react for 4 hours. After the reaction is completed, cool to room temperature and filter to obtain solid product A; 4) Place solid product A in a CO2 supercritical high-pressure extraction device and supercritically dry it for 5 hours at a temperature of 50℃ and a pressure of 10 MPa using CO2 as the medium to obtain the aerogel fire extinguishing agent.

[0044] Comparative Example 1

[0045] An aerogel fire extinguishing agent is prepared by the following method:

[0046] 1) Add 0.01 parts sodium dodecyl sulfonate and 0.2 parts glass fibers with a diameter of 50-1000 nm and a length of 30-2000 μm to 50 parts water, and stir continuously until uniformly dispersed to obtain dispersion A; 2) Add 20 parts graphene aerogel powder to dispersion A, and stir continuously until uniformly dispersed. Transfer the dispersion product to a hydrothermal reactor lined with polytetrafluoroethylene, seal it, evacuate to a vacuum degree of 0.8, heat to 60℃ and react for 4 hours. After the reaction is completed, cool to room temperature and filter to obtain solid product A; 3) Place solid product A in a CO2 supercritical high-pressure extraction device, and use CO2 as a medium to supercritically dry at a temperature of 50℃ and a pressure of 10 MPa for 5 hours to obtain aerogel fire extinguishing agent.

[0047] Comparative Example 2

[0048] An aerogel fire extinguishing agent is prepared by the following method:

[0049] 1) Disperse 2 parts of Mg(HCO3)2 powder in 50 parts of water and stir until completely dissolved to obtain a magnesium bicarbonate solution; 2) Add 0.12 parts of sodium dodecyl sulfonate and 0.6 parts of glass fiber with a diameter of 50-1000 nm and a length of 30-2000 μm to the magnesium bicarbonate solution in sequence, and continue stirring until uniformly dispersed to obtain dispersion A; 3) Add 40 parts of graphene aerogel powder to dispersion A, and continue stirring until uniformly dispersed. Transfer the dispersion product to a hydrothermal reactor lined with polytetrafluoroethylene, seal it, evacuate to a vacuum degree of 0.8, heat to 60℃ and react for 4 hours. After the reaction is completed, cool to room temperature and filter to obtain solid product A; 4) Place solid product A in a CO2 supercritical high-pressure extraction device and supercritically dry it for 5 hours at a temperature of 50℃ and a pressure of 10 MPa using CO2 as the medium to obtain the aerogel fire extinguishing agent.

[0050] Comparative Example 3

[0051] An aerogel fire extinguishing agent is prepared by the following method:

[0052] 1) Disperse 2 parts of Mg(HCO3)2 powder in 50 parts of water and stir until completely dissolved to obtain a magnesium bicarbonate solution; 2) Add 0.01 parts of sodium dodecyl sulfonate to the magnesium bicarbonate solution and stir continuously until evenly dispersed to obtain dispersion A; 3) Add 20 parts of graphene aerogel powder to dispersion A and stir continuously until evenly dispersed. Transfer the dispersion product to a hydrothermal reactor lined with polytetrafluoroethylene, seal it, evacuate to a vacuum degree of 0.8, heat to 60℃ and react for 4 hours. After the reaction is completed, cool to room temperature and filter to obtain solid product A; 4) Place solid product A in a CO2 supercritical high-pressure extraction device and supercritically dry it for 5 hours at a temperature of 50℃ and a pressure of 10MPa using CO2 as the medium to obtain the aerogel fire extinguishing agent.

[0053] Comparative Example 4

[0054] An aerogel fire extinguishing agent is prepared by the following method:

[0055] 1) Weigh 50 parts of water into a container, add 0.01 parts of sodium dodecyl sulfonate, and stir continuously until evenly dispersed to obtain dispersion A; 2) Add 20 parts of graphene aerogel powder to dispersion A, stir continuously until evenly dispersed, transfer the dispersion product to a hydrothermal reactor lined with polytetrafluoroethylene, seal, evacuate to a vacuum degree of 0.8, heat to 60℃ and react for 4 hours, cool to room temperature after the reaction, and filter to obtain solid product A; 3) Place solid product A in a CO2 supercritical high-pressure extraction device, use CO2 as a medium and supercritically dry at a temperature of 50℃ and a pressure of 10MPa for 5 hours to obtain aerogel fire extinguishing agent.

[0056] Comparative Example 5

[0057] A silica aerogel fire extinguishing agent was prepared according to the method described in Chinese patent CN111840880A.

[0058] Comparative Example 6

[0059] Use pure water as the extinguishing agent.

[0060] Fire extinguishing performance test

[0061] The same batch of lithium iron phosphate batteries were heated to 200°C using a heating element. When the lithium-ion batteries began to thermally runaway, the extinguishing agent from the example or comparative example was released. The surface temperature of the batteries was tested by thermocouples on the battery surface at the start of extinguishing and after extinguishing, and the time for the open flame to be extinguished was recorded.

[0062] Table 1. Experimental results of extinguishing fires caused by thermal runaway of lithium iron phosphate.

[0063] Experiment number Battery maximum temperature Battery minimum temperature Flame extinguishing time Whether it reignites Example 1 655℃ 113℃ 10s no Example 2 658℃ 109℃ 9s no Example 3 653℃ 115℃ 11s no Comparative Example 1 667℃ 142℃ 23s yes Comparative Example 2 646℃ 125℃ 15s no Comparative Example 3 662℃ 127℃ 16s no Comparative Example 4 679℃ 156℃ 30s yes Comparative Example 5 650℃ 131℃ 25s no Comparative Example 6 630℃ 163℃ 160s yes

[0064] The experimental results in the table show that after the release of the aerogel fire extinguishing agent, the battery flame was extinguished and the temperature dropped rapidly. The fire extinguishing agent in the embodiments of the present invention can effectively reduce the battery temperature, stop the chemical reaction inside the battery, and prevent the battery temperature from rising again after a period of time. At the same time, the battery treated with the embodiments of the present invention did not reignite, indicating that the aerogel fire extinguishing agent prepared in the present invention has a certain effect on extinguishing fires and inhibiting reignition of lithium iron phosphate batteries.

[0065] The comparative experimental results show that the presence of magnesium bicarbonate effectively inhibits the reignition of lithium batteries. This is presumably because as the lithium battery burns, the temperature rises, and magnesium bicarbonate gradually decomposes. On one hand, it absorbs heat, lowering the battery temperature; on the other hand, the carbon dioxide produced during decomposition isolates oxygen, inhibiting combustion. Simultaneously, the products MgO and magnesium hydroxide also have a coating effect on combustion materials and a flame-retardant effect. Furthermore, the comparison between the examples and the comparative examples shows that the presence of inorganic fibers also reduces the battery temperature to some extent, achieving a heat-insulating and flame-retardant effect. The flame extinguishing time also demonstrates that the aerogel fire extinguishing agent of this invention has a good suppressive and extinguishing effect on lithium battery fires, and can effectively reduce the battery temperature compared to silica fire extinguishing agents.

[0066] The above provides a detailed description of an aerogel fire extinguishing agent and its preparation method. The above content, combined with specific preferred embodiments, further illustrates the present invention and should not be construed as limiting the specific implementation of the invention to these descriptions. For those skilled in the art, the structure of this invention can be flexibly varied without departing from its concept, leading to the derivation of a series of products. Any simple deductions or substitutions should be considered as falling within the patent protection scope defined by the submitted claims.

Claims

1. An aerogel fire extinguishing agent, characterized in that, The extinguishing agent is prepared from the following raw materials in parts by weight: 10-30 parts of graphene aerogel powder; 1-5 parts of Mg(HCO3)2 powder; Inorganic fibers: 0.1~0.5 parts; Sodium dodecyl sulfonate 0.01~0.1 parts; 50-100 parts water; The inorganic fiber is one or more of glass fiber, basalt fiber and alumina fiber.

2. The aerogel fire extinguishing agent according to claim 1, characterized in that, The extinguishing agent is prepared from the following raw materials in parts by weight: 20 parts of graphene aerogel powder; Two parts of Mg(HCO3)2 powder; 0.2 parts of inorganic fiber; Sodium dodecyl sulfonate 0.01 parts; 50 parts water.

3. The aerogel fire extinguishing agent according to claim 1, characterized in that, The inorganic fiber has a diameter of 50–1000 nm and a length of 30–2000 μm.

4. A method for preparing the aerogel fire extinguishing agent according to any one of claims 1 to 3, characterized in that, Includes the following steps: 1) Disperse 1-5 parts of Mg(HCO3)2 powder in 50-100 parts of water, stir until completely dissolved, and obtain magnesium bicarbonate solution; 2) Add 0.01~0.1 parts of sodium dodecyl sulfonate and 0.1~0.5 parts of inorganic fiber to the magnesium bicarbonate solution in sequence, and continue stirring until the dispersion is uniform to obtain dispersion A; 3) Add 10-30 parts of graphene aerogel powder to dispersion A, stir continuously until uniformly dispersed, transfer the dispersion product to a hydrothermal reactor with a polytetrafluoroethylene liner, seal, evacuate to a vacuum degree of 0.8, heat to 50-80℃ and react for 4 hours, cool to room temperature after the reaction is completed, and filter to obtain solid product A. 4) Place solid product A in a CO2 supercritical high-pressure extraction device and perform supercritical drying for 3-5 hours at a temperature of 30-60℃ and a pressure of 5-10MPa using CO2 as the medium to obtain aerogel fire extinguishing agent.

5. The method for preparing the aerogel fire extinguishing agent according to claim 4, characterized in that, In step 3), the hydrothermal reaction is carried out at 60°C for 4 hours, and the filtration is performed by vacuum filtration.

6. The method for preparing the aerogel fire extinguishing agent according to claim 4, characterized in that, Step 4) In the CO2 supercritical high-pressure extraction, CO2 is used as the medium to carry out supercritical drying for 5 hours at a temperature of 50℃ and a pressure of 10MPa.

7. The application of an aerogel fire extinguishing agent according to any one of claims 1 to 3 or an aerogel fire extinguishing agent prepared by any one of claims 4 to 6 in extinguishing battery fires, characterized in that, The batteries include: lithium batteries, nickel-metal hydride batteries, zinc-air batteries, or nickel-cadmium batteries.