Thermally responsive aerogel-enhanced gel foam extinguishing agent and methods of making and using the same

Abstract

The application discloses a kind of thermal response aerogel reinforced gel foam extinguishing agent, mainly including surfactant, thermal response polymer, nano-aerogel.On this basis, the inventor has also established the corresponding preparation method.The application forms the three-phase gel foam covering layer by the synergistic effect of foam covering, thermal response gelation and nano-aerogel solid-phase heat insulation support, which has the advantages of rapid covering, water retention and low thermal conductivity insulation capacity.Actual use shows that the application has good fire extinguishing performance, especially suitable for lithium-ion battery fire protection, and can be widely applied to electric vehicle battery pack, energy storage power station battery pack and lithium-ion battery production, transportation and storage scene thermal runaway fire protection.

Description

Technical Field

[0001] This invention belongs to the field of fire protection materials and new energy battery safety technology, and in particular relates to a thermally responsive aerogel-reinforced gel foam fire extinguishing agent, its preparation method and application. Background Technology

[0002] With the rapid development of new energy vehicles, energy storage power stations, and mobile electronic devices, lithium-ion batteries are widely used due to their high energy density and long cycle life. However, lithium-ion batteries may experience thermal runaway under conditions of overcharging, short circuits, mechanical damage, or external high temperatures. During thermal runaway, the battery continuously releases heat and flammable gases, and such fires are characterized by high temperatures, rapid spread, easy reignition, and difficulty in complete cooling.

[0003] Traditional water-based fire extinguishing agents have a cooling effect, but they are prone to leakage or rapid evaporation on tilted or high-temperature battery surfaces, making it difficult to form a durable covering layer; ordinary foam fire extinguishing agents can cover and isolate oxygen, but they are prone to rupture, leakage, and collapse under high temperature and strong heat radiation conditions; dry powder fire extinguishing agents can quickly suppress open flames, but their cooling capacity is insufficient, making it difficult to suppress thermal runaway reactions and reignition inside the battery.

[0004] Temperature-sensitive gels or temperature-sensitive foam fire extinguishing agents can increase the viscosity of the system as the temperature rises, thereby improving water retention and fire resistance. However, foam systems that rely solely on the gelation of temperature-sensitive polymer water films have a thermal insulation structure mainly derived from the polymer gel network, lacking a solid-phase nanoporous thermal insulation framework. When only thickening systems such as cellulose gels are used, stability is mainly improved by the polymer network, making it difficult to simultaneously achieve enhanced foam liquid film mechanical properties, low thermal conductivity insulation, and long-term adhesion under lithium-ion battery thermal runaway scenarios. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a high-performance thermally responsive aerogel-reinforced gel foam fire extinguishing agent, its preparation method and application.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0007] Thermally responsive aerogel-reinforced gel foam fire extinguishing agents mainly include surfactants, thermally responsive polymers, and nano-aerogels.

[0008] The aforementioned extinguishing agents also include flame retardants, dispersants, chelating agents, preservatives, and water.

[0009] The above-mentioned fire extinguishing agent is made from the following components in parts by weight: 0.5 to 2 parts surfactant, 0.1 to 1 part thermally responsive polymer, 0.1 to 1 part nano-aerogel, 1 to 5 parts flame retardant, 0.5 to 3 parts dispersant, 0.1 to 1 part chelating agent, 0.05 to 0.2 parts preservative, with the balance being water, and the total amount of all components is 100 parts.

[0010] The surfactant is a nonionic surfactant and / or an amphoteric surfactant; the nonionic surfactant is one or more of stearyl alcohol polyoxypropylene ether, dodecyl glycoside, oleamide polyoxyethylene ether, and alkyl sugar alcohol ether; the amphoteric surfactant is one or more of cocamidopropyl sulfobetaine, potassium lauroyl glutamate, sodium lauroyl glutamate, and alkyl hydroxy betaine.

[0011] The thermally responsive polymer is one or more of the following: poly(N-isopropylacrylamide), polyvinyl alcohol, chitosan, methylcellulose, hydroxyethyl methylcellulose, hydroxypropyl methylcellulose, carboxymethylcellulose, polyacrylamide, and alginate.

[0012] Nano-aerogels are one or more of silica aerogels, alumina aerogels, and silica-alumina composite aerogels.

[0013] The flame retardant is one or more of expanded graphite, diammonium hydrogen phosphate, aluminum hydroxide, and magnesium hydroxide;

[0014] The dispersant is one or more of propylene glycol, ethylene glycol, ethylene glycol butyl ether, and glycerin;

[0015] The chelating agent is one or more of the following: ethylenediaminetetraacetic acid and its sodium salt, diethylenetriaminepentaacetic acid and its salts, aminotrimethylphosphonic acid, hydroxyethylidene diphosphonic acid, sodium gluconate, and sodium citrate.

[0016] The preservative is one or more of isothiazolinone, phenoxyethanol, benzoic acid and its salts, sorbic acid and its salts, and p-hydroxybenzoic acid esters.

[0017] The thermally responsive polymer is a compound of poly(N-isopropylacrylamide) and polyvinyl alcohol, chitosan and polyvinyl alcohol, or poly(N-isopropylacrylamide) and hydroxypropyl methylcellulose; the nano-aerogel is a compound of hydrophilic silica aerogel and hydrophobic silica aerogel; the flame retardant is a compound of expanded graphite and diammonium hydrogen phosphate or diammonium hydrogen phosphate and magnesium hydroxide.

[0018] The mass ratio of hydrophilic silica aerogel to hydrophobic silica aerogel is 1:0.3 to 1:2.0.

[0019] The preparation method of the above-mentioned fire extinguishing agent includes the following steps:

[0020] S1. Add water to the reaction vessel, add dispersant and chelating agent, and stir until fully dissolved to form a homogeneous aqueous phase;

[0021] S2, add amphoteric surfactant and nonionic surfactant in sequence, stir at low speed until completely dissolved to form a stable foam base liquid;

[0022] S3, the thermally responsive polymer is slowly added to the foam base liquid to ensure that the polymer is fully dispersed and does not gel prematurely;

[0023] S4. Slowly add the nano-aerogel and stir at low speed to avoid particle agglomeration, so that the nano-aerogel is evenly dispersed in the foam base liquid.

[0024] S5, add flame retardant and corrosion inhibitor and stir evenly to ensure uniform distribution of all components, thus obtaining the thermally responsive aerogel-reinforced gel foam fire extinguishing agent. After preparation, the fire extinguishing agent can be stored in a sealed container to maintain good flowability and sprayability.

[0025] In step S3, the system temperature is controlled at 25–30°C;

[0026] In step S4, hydrophilic silica aerogel is added first, followed by hydrophobic silica aerogel, or the hydrophilic silica aerogel and hydrophobic silica aerogel are pre-dispersed before being added, so that the nano-aerogel is simultaneously distributed in the aqueous gel network and the foam gas-liquid interface.

[0027] The above-mentioned thermally responsive aerogel-reinforced gel foam extinguishing agent is used in fire protection.

[0028] Fire protection refers to fire protection for lithium-ion batteries.

[0029] To address the problems existing in current fire extinguishing agents, the inventors have developed a thermally responsive aerogel-reinforced gel foam fire extinguishing agent, mainly comprising surfactants, thermally responsive polymers, and nano-aerogels. Through the synergistic effect of the surfactant system's foam stabilizing effect, the thermally responsive polymer's gelation effect, and the nano-aerogel's solid-phase support effect, the three-phase foam system of this invention can maintain an intact foam gel coating layer under high-temperature conditions, significantly delaying the propagation of thermal runaway from lithium-ion batteries, reducing the risk of reignition, and achieving a highly efficient fire extinguishing effect through continuous heat absorption, oxygen isolation, and blocking heat conduction. Based on this, the inventors have also established a corresponding preparation method.

[0030] Unlike fire extinguishing agents that rely solely on temperature-sensitive foam or cellulose gel foam, this invention does not simply rely on temperature-sensitive polymers to increase water film viscosity, nor does it solely rely on cellulose gel to improve foam stability. Instead, it achieves a three-phase gel foam covering layer through the synergistic effect of foam coverage, thermally responsive gelation, and solid-phase thermal insulation support from nano-aerogels. This layer combines rapid coverage, water retention, and low thermal conductivity insulation capabilities. Practical application demonstrates that this invention exhibits excellent fire extinguishing performance, making it particularly suitable for lithium-ion battery fire protection. It can be widely applied to thermal runaway fire protection in electric vehicle battery packs, energy storage power station battery modules, and lithium-ion battery production, transportation, and storage scenarios. When a lithium-ion battery fire occurs, the extinguishing agent of this invention is sprayed onto the surface of the lithium-ion battery or the gap between battery modules through a compressed air foam generator. When the battery surface temperature rises, the thermally responsive polymer forms a three-dimensional gel network, the nano-aerogel provides solid-phase thermal insulation support, and the flame retardant reduces the flame temperature. A stable, water-retaining, heat-insulating, and anti-reignition three-phase gel foam covering layer is formed on the surface of the lithium-ion battery, which enhances adhesion, water retention, and heat insulation capabilities, thereby inhibiting the spread of thermal runaway and reignition of the lithium-ion battery. Detailed Implementation

[0031] I. Fire Extinguishing Agent Design Principles

[0032] Surfactants are used to generate initial foam and maintain a stable structure at the gas-liquid interface. The surfactant system forms stable foam during the fire extinguishing process, providing a stable interfacial environment for the gelation of thermally responsive polymers and ensuring that the foam has good spreadability and retention on high-temperature surfaces. This provides interfacial stability conditions for the gelation of thermally responsive polymers and the embedding of nano-aerogels.

[0033] Thermally responsive polymers undergo a solution-gel phase transition upon temperature increase, forming a continuous and stable three-dimensional gel network layer, which is a key structural unit for achieving high-temperature adhesion and water retention capabilities. This gel network can form a buffer isolation layer on the surface of lithium-ion batteries or their module gaps, significantly slowing down heat conduction and prolonging the residence time of the extinguishing agent on the surface, providing the necessary conditions for the stable existence of the foam structure.

[0034] Nano-aerogels, acting as solid-phase support units, are uniformly dispersed within a liquid-phase network formed by thermally responsive polymers and a surfactant-stabilized foam film. They are distributed at the foam liquid film and Plateau boundary, enhancing the foam's mechanical strength and thermal stability through high specific surface area, porous structure, and interfacial adsorption, slowing down liquid film drainage, and blocking heat conduction. The nano-aerogels and the three-dimensional gel network formed by the thermally responsive polymers at high temperatures together constitute a gel-aerogel composite framework, transforming the extinguishing agent from a foam mixture easily transported and sprayed at room temperature into a stable three-phase gel foam covering layer at high temperatures. Hydrophilic aerogels facilitate dispersion within the aqueous gel network, while hydrophobic aerogels are beneficial for adsorption or enrichment at the foam gas-liquid interface. Together, they synergistically improve the foam liquid film strength, inhibit drainage, and form a porous, thermally insulating support structure.

[0035] Flame retardants are used to enhance the flame suppression capabilities of fire extinguishing agents. Under high-temperature conditions, flame retardants reduce flame temperature through endothermic decomposition or by forming an insulating layer.

[0036] Dispersants are used to adjust the system's solubility and improve low-temperature flowability. This component can improve the dispersion of surfactants, thermally responsive polymers, and nano-aerogels in the aqueous phase, and enhance the foam's spreading ability on burning surfaces.

[0037] Chelating stabilizers are used to complex metal ions in the aqueous phase, thereby reducing their impact on the stability of surfactants and polymer structures.

[0038] Preservatives are used to inhibit the growth of microorganisms during the storage of fire extinguishing agents, thereby extending the product's shelf life.

[0039] The extinguishing agent exhibits good fluidity and foaming properties at room temperature, and can be delivered and sprayed as a foam mixture via a compressed air foam generator. The foam covers the battery surface at room temperature. As the battery temperature rises, the thermally responsive polymer rapidly gels to form a stable foam gel coating layer. Nano-aerogels provide solid-phase support and block heat conduction, while flame retardants reduce the flame temperature, thereby effectively inhibiting the spread of thermal runaway and reignition.

[0040] Through the synergistic effect of the above components, after the fire extinguishing agent of this invention is sprayed into the lithium-ion battery or its module gaps, the nano-aerogel is dispersed in the form of solid particles in the foam liquid film and foam Plateau boundary. The thermally responsive polymer forms a liquid-phase three-dimensional gel network when the temperature rises. The nano-aerogel and the liquid-phase three-dimensional gel network together constitute a gel-aerogel composite skeleton, thereby forming a three-phase gel foam covering layer (adhesion duration not less than 20 min) on the high-temperature surface of the lithium-ion battery. Through multiple mechanisms such as foam covering to isolate oxygen, gel network to retain water, nano-aerogel low thermal conductivity insulation, and flame retardant heat absorption and flame suppression, the fire extinguishing agent effectively inhibits the spread of thermal runaway and reignition. Without the synergistic effect of thermally responsive polymer or suitable surfactant system, nano-aerogel is difficult to play a long-term supporting and insulating role in high-temperature environment; without nano-aerogel, it is difficult to form a low thermal conductivity porous insulation skeleton by relying solely on the gelation of the temperature-sensitive polymer water film.

[0041] Therefore, this extinguishing agent is particularly suitable for rapid fire suppression and safety control in electric vehicle battery packs, energy storage power station battery packs, and lithium-ion battery production, transportation, and storage scenarios.

[0042] II. Application of Extinguishing Agents

[0043] Example 1

[0044] The preparation and application of the fire extinguishing agent described in this invention are illustrated below using the preparation of 100 g of thermally responsive aerogel-reinforced three-phase foam fire extinguishing agent as an example. The prepared foam liquid can be sprayed through a compressed air foam generator for extinguishing lithium-ion battery thermal runaway fires.

[0045] First, 45.0 g of deionized water was added to a reaction vessel, along with 1.5 g of propylene glycol as a dispersant and 0.5 g of disodium ethylenediaminetetraacetate as a chelating agent. The mixture was stirred until a homogeneous aqueous phase was formed. Then, 0.6 g of the amphoteric surfactant potassium lauroyl glutamate and 0.9 g of the nonionic surfactant stearyl alcohol polyoxypropylene ether were added sequentially. The mixture was stirred at low speed for 10–20 min until completely dissolved, yielding the foam base liquid. Next, 0.5 g of the thermoresponsive polymer poly(N-isopropylacrylamide) and 0.1 g of polyvinyl alcohol were slowly added, while controlling the system temperature at 25–30 °C to ensure sufficient polymer dispersion without premature gelation. Subsequently, nano-aerogels, including 0.2 g of hydrophilic silica aerogel and 0.3 g of hydrophobic silica aerogel, were slowly added to the liquid system, with low-speed stirring to prevent particle agglomeration and ensure uniform dispersion.

[0046] Finally, add 1.8 g of flame retardant expanded graphite and 1.2 g of diammonium hydrogen phosphate, as well as 0.1 g of preservative isothiazolinone, and add the remaining deionized water to a final volume of 100 g. Continue stirring until homogeneous to obtain a high-temperature stable fire extinguishing agent system. After preparation, store the fire extinguishing agent in a sealed container to maintain good flowability and sprayability.

[0047] The performance of the thermally responsive aerogel-reinforced three-phase foam fire extinguishing agent prepared in Example 1 was tested, and the results are as follows: surface tension: 26.0 mN / m; 25% separation time: 38.5 min; extinguishing time in a lithium battery simulated fire: 58 s; anti-burning time: 27.0 min; high-temperature surface adhesion duration: approximately 22 min.

[0048] Example 2

[0049] The preparation and application of the fire extinguishing agent described in this invention are illustrated below using the preparation of 100 g of thermally responsive aerogel-reinforced three-phase foam fire extinguishing agent as an example. The prepared foam liquid can be sprayed through a compressed air foam generator for extinguishing lithium-ion battery thermal runaway fires.

[0050] First, 45.0 g of deionized water was added to a reaction vessel, along with 1.2 g of dispersant ethylene glycol butyl ether and 0.3 g of chelating agent sodium citrate. The mixture was stirred until a homogeneous aqueous phase was formed. Subsequently, 0.8 g of amphoteric surfactant cocamidopropyl sulfobetaine and 0.7 g of nonionic surfactant dodecyl glycoside were added sequentially. The mixture was stirred at low speed for 10–20 min until completely dissolved, yielding the foam base solution.

[0051] Next, 0.6 g of the thermally responsive polymer chitosan and 0.2 g of polyvinyl alcohol were slowly added, while the system temperature was controlled at 25–30 °C to ensure that the polymers were fully dispersed and did not gel prematurely. Subsequently, nano-aerogels, 0.3 g of hydrophilic silica aerogel and 0.1 g of hydrophobic silica aerogel, were slowly added to the liquid system, and low-speed stirring was used to avoid particle agglomeration and ensure uniform dispersion.

[0052] Finally, add 1.5 g of flame retardant diammonium hydrogen phosphate and 1.5 g of magnesium hydroxide, as well as 0.1 g of preservative phenoxyethanol, and add the remaining deionized water to a final volume of 100 g. Continue stirring until homogeneous to obtain a high-temperature stable fire extinguishing agent system. After preparation, store the fire extinguishing agent in a sealed container to maintain good flowability and sprayability.

[0053] The performance of the foam liquid prepared in Example 2 was tested, and the results are as follows: surface tension: 26.3 mN / m; 25% separation time: 35.0 min; extinguishing time in a simulated lithium battery fire: 60 s; fire resistance time: 25.5 min; duration of high-temperature surface adhesion: approximately 23 min.

[0054] Example 3

[0055] The preparation and application of the fire extinguishing agent described in this invention are illustrated below using the preparation of 100 g of thermally responsive aerogel-reinforced three-phase foam fire extinguishing agent as an example. The prepared foam liquid can be sprayed through a compressed air foam generator for extinguishing lithium-ion battery thermal runaway fires.

[0056] First, 45.0 g of deionized water was added to a reaction vessel, along with 1.0 g of dispersant propylene glycol and 0.2 g of chelating agent disodium ethylenediaminetetraacetate. The mixture was stirred until a homogeneous aqueous phase was formed. Subsequently, 0.7 g of amphoteric surfactant potassium lauroyl glutamate and 1.0 g of nonionic surfactant oleamide polyoxyethylene ether were added sequentially. The mixture was stirred at low speed for 10–20 min until completely dissolved, yielding the foam base solution.

[0057] Next, 0.4 g of the thermally responsive polymer poly(N-isopropylacrylamide) and 0.2 g of hydroxypropyl methylcellulose were slowly added, while the system temperature was controlled at 25–30 °C to ensure that the polymers were fully dispersed and did not gel prematurely. Subsequently, 0.3 g of silica aerogel and 0.3 g of alumina aerogel were slowly added to the liquid system, and the mixture was stirred at low speed to avoid particle agglomeration and ensure uniform dispersion.

[0058] Finally, add 2.0 g of flame retardant expanded graphite, 1.5 g of magnesium hydroxide, and 0.1 g of preservative isothiazolinone, and add the remaining deionized water to a final volume of 100 g. Continue stirring until homogeneous to obtain a high-temperature stable fire extinguishing agent system. After preparation, store the fire extinguishing agent in a sealed container to maintain good flowability and sprayability.

[0059] The performance of the foam liquid prepared in Example 3 was tested, and the results are as follows: surface tension: 25.7 mN / m; 25% separation time: 40.3 min; extinguishing time in a simulated lithium battery fire: 55 s; anti-burning time: 28.6 min; duration of high-temperature surface adhesion: approximately 25.5 min.

[0060] Comparative Example 1 (Non-thermal-responsive polymer)

[0061] The preparation and application of the comparative example described in this invention are illustrated below using the preparation of 100 g of foam extinguishing agent as an example. The obtained foam liquid can be sprayed through a compressed air foam generator for extinguishing lithium-ion battery thermal runaway fires.

[0062] First, 45.0 g of deionized water was added to a reaction vessel, along with 1.0 g of dispersant propylene glycol and 0.2 g of chelating agent disodium ethylenediaminetetraacetate. The mixture was stirred until a homogeneous aqueous phase was formed. Subsequently, 0.7 g of amphoteric surfactant potassium lauroyl glutamate and 1.0 g of nonionic surfactant oleamide polyoxyethylene ether were added sequentially. The mixture was stirred at low speed for 10–20 min until completely dissolved, yielding the foam base solution.

[0063] Next, the nano-aerogels were slowly added to the liquid system, including 0.3 g of silica aerogel and 0.3 g of alumina aerogel. The mixture was stirred at low speed to avoid particle agglomeration and ensure uniform dispersion.

[0064] Finally, add 2.0 g of flame retardant expanded graphite, 1.5 g of magnesium hydroxide, and 0.1 g of preservative isothiazolinone, and add the remaining deionized water to a final volume of 100 g. Continue stirring until homogeneous to obtain a high-temperature stable fire extinguishing agent system. After preparation, store the fire extinguishing agent in a sealed container to maintain good flowability and sprayability.

[0065] The performance of the comparative foam liquid was tested, and the results are as follows: surface tension: 25.5 mN / m; 25% separation time: 33.0 min; extinguishing time in a simulated lithium battery fire: 65 s; fire resistance time: 23.8 min; duration of adhesion to high-temperature surfaces: approximately 20 min.

[0066] Comparative Example 2 (without nano-aerogel foam)

[0067] The preparation and application of the comparative example described in this invention are illustrated below using the preparation of 100 g of foam extinguishing agent as an example. The obtained foam liquid can be sprayed through a compressed air foam generator for extinguishing lithium-ion battery thermal runaway fires.

[0068] First, 45.0 g of deionized water was added to a reaction vessel, along with 1.0 g of dispersant propylene glycol and 0.2 g of chelating agent disodium ethylenediaminetetraacetate. The mixture was stirred until a homogeneous aqueous phase was formed. Subsequently, 0.7 g of amphoteric surfactant potassium lauroyl glutamate and 1.0 g of nonionic surfactant oleamide polyoxyethylene ether were added sequentially. The mixture was stirred at low speed for 10–20 min until completely dissolved, yielding the foam base solution.

[0069] Next, slowly add 0.4 g of the thermally responsive polymer poly-N-isopropylacrylamide and 0.2 g of hydroxypropyl methylcellulose, while controlling the system temperature at 25-30°C to ensure that the polymer is fully dispersed and does not gel prematurely.

[0070] Finally, add 2.0 g of flame retardant expanded graphite, 1.5 g of magnesium hydroxide, and 0.1 g of preservative isothiazolinone, and add the remaining deionized water to a final volume of 100 g. Continue stirring until homogeneous to obtain a high-temperature stable fire extinguishing agent system. After preparation, store the fire extinguishing agent in a sealed container to maintain good flowability and sprayability.

[0071] The performance of the comparative foam liquid was tested, and the results are as follows: surface tension: 25.9 mN / m; 25% separation time: 30.5 min; extinguishing time in a simulated lithium battery fire: 68 s; fire resistance time: 21.0 min; duration of adhesion to high-temperature surfaces: approximately 18 min.

[0072] Comparative Example 3 (Traditional Foam Fire Extinguishing Agent)

[0073] The preparation and application of the comparative example described in this invention are illustrated below using the preparation of 100 g of foam extinguishing agent as an example. The obtained foam liquid can be sprayed through a compressed air foam generator for extinguishing lithium-ion battery thermal runaway fires.

[0074] First, 45.0 g of deionized water was added to a reaction vessel, along with 1.0 g of dispersant propylene glycol and 0.2 g of chelating agent disodium ethylenediaminetetraacetate. The mixture was stirred until a homogeneous aqueous phase was formed. Subsequently, 0.7 g of amphoteric surfactant potassium lauroyl glutamate and 1.0 g of nonionic surfactant oleamide polyoxyethylene ether were added sequentially. The mixture was stirred at low speed for 10–20 min until completely dissolved, yielding the foam base solution.

[0075] Next, add 2.0 g of flame retardant expanded graphite and 1.5 g of magnesium hydroxide, as well as 0.1 g of preservative isothiazolinone. Add the remaining deionized water to a final volume of 100 g, and continue stirring until homogeneous to obtain a high-temperature stable fire extinguishing agent system. After preparation, store the fire extinguishing agent in a sealed container to maintain good flowability and sprayability.

[0076] The performance of the comparative foam liquid was tested, and the results are as follows: surface tension: 25.4 mN / m; 25% separation time: 10.0 min; extinguishing time in a simulated lithium battery fire: 75 s; fire resistance time: 15.0 min; duration of adhesion to high-temperature surfaces: approximately 12 min.

[0077] The foam liquid formulations and performance test results of the above examples and comparative examples are summarized in Tables 1 and 2.

[0078] As shown in Tables 1 and 2, the surface tension of each formulation remained at 25.4–26.3 mN / m, indicating that different fluorine-free surfactant systems all have a good foaming basis, but the difference in surface tension is not the main factor affecting the fire extinguishing performance.

[0079] Examples 1–3, which simultaneously added thermally responsive polymers and aerogels, exhibited a 25% liquid exudation time of 35.0–40.3 min, a fire extinguishing time of 55–60 s, a fire resistance time of 25.5–28.6 min, and a high-temperature adhesion duration of 22–25.5 min. Their overall performance was significantly superior to the comparative examples. This demonstrates that the combination of thermally responsive polymers and aerogels can enhance the strength and structural stability of the foam liquid film, and improve the foam's coverage, insulation, and adhesion capabilities on high-temperature surfaces.

[0080] Among them, Example 3 showed the best overall performance, with the longest 25% liquid seepage time at 40.3 min and the shortest fire extinguishing time at 55 s. Its fire resistance and high-temperature adhesion time reached 28.6 min and 25.5 min, respectively. In contrast, Comparative Example 3, without the addition of thermally responsive polymers and aerogels, had a 25% liquid seepage time of only 10 min, a fire extinguishing time extended to 75 s, and significantly reduced fire resistance and adhesion performance.

[0081] In summary, thermally responsive polymers and aerogels are key components for improving the stability, heat resistance, and lithium battery fire suppression effect of this fluorine-free foam fire extinguishing agent, and the two have a significant synergistic enhancing effect.

[0082] Table 1 Foaming Liquid Formulation

[0083]

[0084] Table 2. Test Results of Foaming Liquid Formulation

[0085]

Claims

1. A thermally responsive aerogel-reinforced gel foam fire extinguishing agent, characterized in that... It mainly includes surfactants, thermally responsive polymers, and nano-aerogels.

2. The extinguishing agent according to claim 1, characterized in that... It also includes flame retardants, dispersants, chelating agents, preservatives, and water.

3. The extinguishing agent according to claim 2, characterized in that... It is made from the following components in parts by weight: surfactant 0.5-2 parts, thermoresponsive polymer 0.1-1 parts, nano-aerogel 0.1-1 parts, flame retardant 1-5 parts, dispersant 0.5-3 parts, chelating agent 0.1-1 parts, preservative 0.05-0.2 parts, with the balance being water, and the total amount of all components is 100 parts.

4. The extinguishing agent according to claim 1, characterized in that: The surfactant is a nonionic surfactant and / or an amphoteric surfactant; the nonionic surfactant is one or more of stearyl alcohol polyoxypropylene ether, dodecyl glycoside, oleamide polyoxyethylene ether, and alkyl sugar alcohol ether; the amphoteric surfactant is one or more of cocamidopropyl sulfonate betaine, potassium lauroyl glutamate, sodium lauroyl glutamate, and alkyl hydroxy betaine. The thermally responsive polymer is one or more of the following: poly(N-isopropylacrylamide), polyvinyl alcohol, chitosan, methylcellulose, hydroxyethyl methylcellulose, hydroxypropyl methylcellulose, carboxymethylcellulose, polyacrylamide, and alginate. The nano-aerogel is one or more of silica aerogel, alumina aerogel, and silica-alumina composite aerogel. The flame retardant is one or more of expanded graphite, diammonium hydrogen phosphate, aluminum hydroxide, and magnesium hydroxide; The dispersant is one or more of propylene glycol, ethylene glycol, ethylene glycol butyl ether, and glycerin; The chelating agent is one or more of the following: ethylenediaminetetraacetic acid and its sodium salt, diethylenetriaminepentaacetic acid and its salts, aminotrimethylphosphonic acid, hydroxyethylidene diphosphonic acid, sodium gluconate, and sodium citrate. The preservative is one or more of isothiazolinone, phenoxyethanol, benzoic acid and its salts, sorbic acid and its salts, and p-hydroxybenzoic acid esters.

5. The extinguishing agent according to claim 4, characterized in that: The thermally responsive polymer is a compound of poly(N-isopropylacrylamide) and polyvinyl alcohol, chitosan and polyvinyl alcohol, or poly(N-isopropylacrylamide) and hydroxypropyl methylcellulose; the nano-aerogel is a compound of hydrophilic silica aerogel and hydrophobic silica aerogel; the flame retardant is a compound of expanded graphite and diammonium hydrogen phosphate or diammonium hydrogen phosphate and magnesium hydroxide.

6. The extinguishing agent according to claim 5, characterized in that: The mass ratio of the hydrophilic silica aerogel to the hydrophobic silica aerogel is 1:0.3 to 1:2.

0.

7. The method for preparing the extinguishing agent according to claim 1, characterized in that... Includes the following steps: S1, add water to the reaction vessel, add dispersant and chelating agent, and stir until a homogeneous aqueous phase is formed; S2, add amphoteric surfactant and nonionic surfactant in sequence, stir until completely dissolved to form a stable foam base liquid; S3, slowly add the thermally responsive polymer to the foam base liquid; S4. Slowly add the nano-aerogel to evenly disperse it in the foam base liquid. S5, add flame retardant and preservative and stir evenly to obtain thermally responsive aerogel-reinforced gel foam fire extinguishing agent.

8. The method for preparing the extinguishing agent according to claim 7, characterized in that: In step S3, the system temperature is controlled at 25–30°C; In step S4, the hydrophilic silica aerogel is added first, followed by the hydrophobic silica aerogel, or the hydrophilic silica aerogel and hydrophobic silica aerogel are pre-dispersed before being added.

9. The application of the extinguishing agent according to any one of claims 1 to 6 or the thermally responsive aerogel-reinforced gel foam extinguishing agent obtained by any one of the preparation methods according to claims 7 to 8 in fire protection.

10. The application according to claim 9, characterized in that: The fire protection mentioned is for lithium-ion battery fire protection.

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