Special gel type water-based fire extinguishing agent for low-conductivity and high-stability lithium battery

Abstract

The invention relates to the technical field of fire extinguishing materials, in particular to a low-conductivity high-stability gel type water-based fire extinguishing agent. The composite material comprises the following raw materials in parts by weight: 1-3 parts of modified nano silicon dioxide aerogel; 1-3 parts of nano aluminum hydroxide; 1 to 3 parts of trimethyl phosphate; 20 to 35 parts of an emulsifier OP-10; 10-15 parts of an antifreeze agent; 0.5 to 1.5 parts of a fluorocarbon surfactant; 0.5 to 1.5 parts of a bacteriostatic agent; 0.5-2 parts of a foam stabilizer; 0.3 to 1.5 parts of xanthan gum; 0.1 to 0.8 part of calcium lactate; 0.5 to 2 parts of bentonite; 0.5 to 2 parts of mica; 0.1 to 1 part of a conditioning agent; and 40-60 parts of deionized water. And the prepared porous insulation network, phosphate free radical capture and xanthan gum calcium lactate gel have a synergistic effect, so that the fire extinguishing agent has the characteristics of low conductivity, rapid cooling and long-acting combustion suppression, and is suitable for emergency protection of fire disasters of lithium batteries of electric automobiles and energy storage systems.

Description

Technical Field

[0001] This invention relates to the field of fire extinguishing materials technology, specifically to a low-conductivity, highly stable gel-type water-based fire extinguishing agent suitable for lithium-ion battery fires and its preparation method. Background Technology

[0002] Lithium-ion batteries are widely used in energy storage systems, electric vehicles, and portable electronic devices due to their high energy density and long cycle life. However, they are prone to thermal runaway under operating or abusive conditions, releasing large amounts of flammable gases and highly toxic hydrogen fluoride. This, coupled with intense flames, localized high temperatures, and electrochemical side reactions, can easily lead to serious fires. Given the unique characteristics of lithium battery fires, existing fire extinguishing materials have revealed numerous problems in their application.

[0003] While water-based fire extinguishing agents possess excellent cooling capabilities, their high electrical conductivity (typically exceeding 100 μS / cm) poses a significant safety hazard when used with battery modules, potentially causing secondary disasters such as electrical short circuits. Dry powder fire extinguishing agents, although capable of suppressing combustion through powder coating, have limited cooling capacity, leave difficult-to-clean residues after extinguishing, and may contaminate battery packs and sensitive electronic equipment. Gaseous fire extinguishing agents, such as heptafluoropropane, while non-conductive, often fail to meet the full-cycle response requirements for lithium battery thermal runaway due to low cooling efficiency, limited spray area, and susceptibility to reignition after extinguishing.

[0004] In recent years, some studies have attempted to introduce foam or gel structures into water-based systems to enhance the adhesion and coverage of extinguishing agents on high-temperature surfaces, prolong their action time, and improve extinguishing efficiency. However, these systems often face prominent problems such as high conductivity, poor structural stability, non-degradable components, and limited functional mechanisms, making it difficult to achieve efficient and long-lasting extinguishing effects while ensuring electrical safety. Furthermore, reducing the ionic components in the system to lower conductivity further weakens its thermal conductivity and foam performance, thus affecting the rapid cooling process in the initial stages of fire extinguishing. The introduction of polymeric additives or inorganic particles to enhance the film-forming properties and stability of foams or gels may lead to the system's biodegradability, increasing the environmental burden. In addition, most existing extinguishing agents focus on physical cooling or oxygen isolation mechanisms, which are insufficient to address the chain combustion reactions triggered by numerous free radicals during lithium battery fires, resulting in a risk of reignition after extinguishing the fire.

[0005] Current technology lacks a water-based fire extinguishing agent that can simultaneously possess high stability, high cooling efficiency, and multiple fire extinguishing mechanisms while maintaining low electrical conductivity. In particular, gel-type products suitable for lithium-ion battery thermal runaway fires are still lacking, and there is an urgent need to achieve performance breakthroughs through collaborative innovation in material systems and structural design. Summary of the Invention

[0006] To overcome the technical challenges of existing lithium-ion battery fire extinguishing materials, such as high conductivity, insufficient cooling capacity, structural instability, limited functional mechanisms, and poor environmental adaptability, this invention provides a low-conductivity, highly stable gel-type water-based fire extinguishing agent specifically for lithium batteries and its preparation method. By constructing an organic-inorganic composite system, introducing modified aerogel to enhance thermal insulation and structural stability, utilizing trimethyl phosphate for free radical capture, and combining a non-ionic emulsion system with a pH-responsive gel network to construct a stable foam layer, this method balances conductivity safety, coverage durability, and synergistic fire extinguishing function. This fire extinguishing agent exhibits low conductivity, rapid cooling, and strong adhesion, effectively preventing lithium battery short circuits and inhibiting the spread of thermal runaway. Furthermore, the system is environmentally friendly and biodegradable, suitable for various lithium battery application scenarios, and possesses good engineering practicality and promising prospects for widespread application.

[0007] The objective of this invention can be achieved through the following technical solutions: A low-conductivity, high-stability lithium battery-specific gel-type water-based fire extinguishing agent comprises the following raw materials in parts by weight: 1-3 parts modified nano-silica aerogel; 1-3 parts nano-aluminum hydroxide; 1-3 parts trimethyl phosphate; 20-35 parts emulsifier OP-10; 10-15 parts antifreeze; 0.5-1.5 parts fluorocarbon surfactant; 0.5-1.5 parts antibacterial agent phenoxyethanol; 0.5-2 parts foam stabilizer; 0.3-1.5 parts xanthan gum; 0.1-0.8 parts calcium lactate; 0.5-2 parts bentonite; 0.5-2 parts mica; 0.1-1 part regulator; and 40-60 parts deionized water.

[0008] Optionally, the modified nano-silica aerogel comprises the following raw materials in parts by weight: 10-20 parts of tetraethyl orthosilicate; 60-100 parts of ethanol; 10-20 parts of deionized water; 0.5-1.5 parts of hydrochloric acid; 0.5-1.5 parts of ammonia; 2-6 parts of methyltriethoxysilane; and 1-3 parts of 3-(dioxophosphoric methylamino)propyltriethoxysilane; wherein the concentration of the hydrochloric acid is 0.01 mol / L; and the volume fraction of the ammonia is 25%.

[0009] Optionally, the emulsifier OP-10 is octylphenol polyoxyethylene ether; the antifreeze is a mixture of ethylene glycol and glycerol in a mass ratio of 2:1 to 1:1; the fluorocarbon surfactant is a mixture of potassium hexafluorohexyl sulfonate and a perfluoroalkyl carboxylate-containing surfactant in a mass ratio of 1:2 to 1:3; the antibacterial agent is phenoxyethanol; and the regulator is a mixture of triethanolamine and sodium hydroxide solution in a mass ratio of 2:1 to 3:1.

[0010] Optionally, the preparation method of modified nano-silica aerogel includes the following steps: (1) After mixing tetraethyl orthosilicate and ethanol evenly, add deionized water and hydrochloric acid and stir to carry out hydrolysis reaction to form a transparent sol; (2) Slowly add ammonia water to the transparent sol while continuing to stir; (3) Add methyltriethoxysilane and 3-(dioxophosphoric methylamino)propyltriethoxysilane in sequence; (4) After aging the reaction product, ethanol is added to perform multiple solvent replacements. (5) Drying to obtain a dry gel; (6) Heat treatment of the dry gel yields a modified nano silica aerogel with stable structure and synergistic regulation of surface functional groups.

[0011] Optionally, in step (1), the hydrolysis reaction temperature is 25-35℃, the time is 30-60 minutes, and the pH is 2.5-3.5; in step (2), the condensation reaction pH is 8-9, and the reaction time is 1-2 hours; in step (3), the surface modification reaction temperature is 20-30℃, and the time is 2-4 hours; in step (5), the drying temperature is 50-80℃, and the drying time is 12-24 hours; in step (6), the heat treatment temperature is 600-800℃, and the heat treatment time is 1-3 hours.

[0012] Optionally, a method for preparing a low-conductivity, high-stability gel-type water-based fire extinguishing agent specifically for lithium batteries includes the following steps: S1, Modified nano-silica aerogel and nano-aluminum hydroxide are added to deionized water and dispersed evenly under stirring to form the first dispersion; S2, after mixing trimethyl phosphate and emulsifier OP-10 evenly, add it to the first dispersion and continue stirring to form an emulsion system; S3, add antifreeze, fluorocarbon surfactant, antibacterial agent phenoxyethanol and foam stabilizer to the emulsion, stir and mix to form a homogeneous main liquid; S4. Add xanthan gum and calcium lactate to the main system liquid, and slowly add the regulator to adjust the pH. Continue stirring to promote the formation of gel structure. S5, after gel formation, add bentonite and mica, and stir thoroughly to improve system stability and adhesion performance; S6, add deionized water, and mix thoroughly again to obtain a low-conductivity, highly stable gel-type water-based fire extinguishing agent specifically for lithium batteries.

[0013] Optionally, the temperature at which the first dispersion is formed in step S1 is 25–35°C.

[0014] Optionally, the pH of gel formation in step S4 is 6.5 to 7.5.

[0015] The beneficial effects of this invention are: The low-conductivity, high-stability gel-type water-based fire extinguishing agent for lithium batteries proposed in this invention addresses the electrical risks, reignition tendency, and insufficient fire extinguishing efficiency during the thermal runaway process of lithium-ion batteries. By constructing a multi-component synergistic foam-gel fire extinguishing system with composite functions, it exhibits excellent comprehensive performance.

[0016] By introducing modified nano-silica aerogel and nano-aluminum hydroxide, combined with a low-electrolysis solvent system, the fire extinguishing agent effectively reduces the ion mobility in the system, and the conductivity can be controlled below 8μS / cm. This significantly improves the protection against the risk of short circuit in the battery cell during fire extinguishing and meets the electrical safety requirements of lithium batteries.

[0017] The constructed pH-responsive gel network exhibits excellent thermal stability and film-forming ability, maintaining a long coverage time at high temperatures to form a dense bubble film that isolates oxygen while achieving continuous cooling, significantly extending the liquid precipitation time. The extinguishing agent demonstrates excellent spreadability and adhesion on the battery surface, effectively covering complex geometries and improving the extinguishing efficiency against thermal runaway sources.

[0018] This fire extinguishing agent is particularly suitable for applications in lithium battery energy storage systems, electric vehicle battery packs, consumer electronics battery packs, and testing platforms, and has significant engineering practicality and broad prospects for promotion. Attached Figure Description

[0019] The invention will now be further described with reference to the accompanying drawings.

[0020] Figure 1 Comparison of infrared spectra of nano-silica and modified nano-silica aerogel; Figure 2 Scanning electron microscope image of modified nano-silica aerogel; Figure 3 A bar chart comparing the conductivity test results of low-conductivity, high-stability lithium battery-specific gels with different formulations. Figure 4 A bar chart comparing the foaming performance test results of low conductivity and high stability lithium battery-specific gels with different formulations; Figure 5 Bar chart comparing the exfoliation time of gel solutions with different ratios for low conductivity and high stability lithium batteries; Figure 6 A bar chart comparing the test results of cooling rates of low-conductivity, high-stability lithium battery-specific gels with different formulations; Figure 7 A bar chart comparing the surface tension test results of low conductivity, high stability lithium battery-specific gels with different formulations. Detailed Implementation

[0021] The present invention will be further described below with reference to specific embodiments. However, the present invention is not limited to the following embodiments. Equivalent adjustments made without departing from the spirit and essence of the present invention should also be considered to fall within the protection scope of the present invention.

[0022] Example 1: In this embodiment, nano-aluminum hydroxide and modified nano-silica are selected as inorganic insulation reinforcing components, combined with trimethyl phosphate and OP-10 emulsifier to form an inhibitor system, and combined with ethylene glycol as the main antifreeze and film-forming component, to construct a gel-type water-based fire extinguishing agent through multi-component synergy.

[0023] like Figure 1 As shown, the original nano-silica in The modified nano-silica aerogel exhibits a broad, blunt, and strong –OH stretching absorption peak, indicating that its surface is rich in hydroxyl groups and readily adsorbs moisture. The peak intensity in the same wavelength band is significantly weakened in the modified nano-silica aerogel, indicating that the hydroxyl groups are replaced by organosilanes, resulting in a significant enhancement of the material's hydrophobicity. Correspondingly, The H–O–H bending vibration decreased from a moderate intensity to a weak peak, further supporting the evidence of a reduction in adsorbed water content. and In the modified sample, a new C–H stretching absorption was observed, while the original sample did not exhibit this feature, proving that the methyl / propyl chain grafting was successful. Clearly appearing The bending vibration peak further confirmed that methyltriethoxysilane was immobilized on the surface. The Si–O–Si asymmetric stretching absorption was the main peak in both samples, but the peak was sharper after modification, indicating that the silicon-oxygen network remained intact and its density was improved. The Si–O–Si symmetric stretching and The Si–O bending peaks also remained stable, indicating that the main framework structure was not damaged.

[0024] Modified samples in Shoulders of P–O–Si bonds appear, and... The region produces P–N and P–O–C related spikes; in addition... Si–C absorption peaks appeared. These new peaks indicate that 3-(dioxophosphorus methylamino)propyltriethoxysilane has been synergistically grafted, introducing phosphorus-nitrogen flame-retardant functional groups and forming Si–C covalent bonds. Combined infrared comparison shows that the modified nano-silica aerogel retains… While constructing the framework, hydroxyl substitution, hydrophobic layer construction, and introduction of phosphorus-nitrogen functional groups were achieved, laying the molecular structural foundation for improving its comprehensive properties such as low electrical conductivity insulation, thermal barrier, and free radical suppression.

[0025] Figure 2It can be seen more intuitively that the modified nano-silica aerogel has a three-dimensional porous structure.

[0026] Preparation steps: S1: Mix 10 parts tetraethyl orthosilicate and 80 parts ethanol evenly, then add 20 parts deionized water and 1 part hydrochloric acid with a concentration of 0.01 mol / L. Stir at room temperature (25-30℃) for 30 minutes to promote the hydrolysis reaction and form a uniform transparent sol. Then, slowly add 25% ammonia water to adjust the pH to 8.5 and continue stirring for 1 hour to promote the condensation reaction and obtain a preliminary colloidal system. Add 4 parts methyltriethoxysilane and 3-(dioxophosphoric acid methylamino)propyltriethoxysilane to the system and continue stirring at 20-30℃ for 3 hours to make the organosilane uniformly grafted onto the surface of the silica framework. After aging the system for 24 hours, perform three ethanol replacements to remove byproducts, and then dry at 60℃ for 18 hours to obtain a dry gel. Finally, heat-treat the dry gel at 700℃ for 2 hours to obtain a dense and hydrophobic modified nano-silica aerogel powder for use in fire extinguishing agent formulations. S2: Take 1 part of nano aluminum hydroxide and 1 part of surface-modified nano silica, add 10 parts of deionized water, and disperse evenly under magnetic stirring to obtain component A; S3: Mix 1 part of trimethyl phosphate and 30 parts of OP-10 emulsifier evenly, then slowly add 20 parts of deionized water and continue stirring to form an emulsion to obtain component B; S4: Mix 10 parts of antifreeze, 1 part of fluorocarbon surfactant, 1 part of phenoxyethanol antibacterial agent and 1 part of foam stabilizer, and add 10 parts of deionized water, stirring to form component C; S5: Mix the above components A, B and C in a volume ratio of 1:1:1, and slowly stir evenly to form composite component D; S6: Add a regulator (ammonia water) to component D to adjust the pH to 8-9, and add deionized water to make the system concentration appropriate; S7: Add xanthan gum and calcium lactate compound, and stir at room temperature until a uniform transparent gel is formed to obtain the finished fire extinguishing agent.

[0027] Example 2: This embodiment increases the amount of trimethyl phosphate added to 2 parts based on Example 1 to enhance its ability to inhibit free radical chain reactions, and appropriately adjusts the proportion of stabilizer.

[0028] Preparation steps: S1: Take 2 parts of nano-aluminum hydroxide and 1 part of modified nano-silica, add 10 parts of deionized water, and stir evenly to form component A; S2: Mix 2 parts of trimethyl phosphate and 30 parts of OP-10, add 20 parts of deionized water, and emulsify at high speed to form component B; S3: Mix 10 parts of antifreeze, 1 part of fluorocarbon surfactant, 1 part of phenoxyethanol, and 1 part of foam stabilizer, add 10 parts of deionized water, and stir to form component C; S4: Combine components A, B, and C in equal volume ratio and stir thoroughly to form component D; S5: Adjust the pH to 8 using ammonia water, and add an appropriate amount of deionized water to adjust the dilution; S6: Add xanthan gum-calcium lactate composite gelling agent to D to form a gel-type fire extinguishing system with good adhesion.

[0029] Example 3: In this embodiment, the proportion of nano-silica is further increased to 2 parts, while the phenoxyethanol content is increased to 1.5 parts to enhance the thermal insulation and microbial stability of the system.

[0030] Preparation steps: S1: Weigh 1 part of nano-aluminum hydroxide and 2 parts of modified nano-silica, mix them, add 10 parts of deionized water, and disperse by ultrasonication to obtain component A; S2: Mix 2 parts of trimethyl phosphate and 30 parts of emulsifier, then slowly add 20 parts of deionized water and stir to emulsify to form component B; S3: Prepare 10 parts of antifreeze, 1 part of fluorocarbon surfactant, 1.5 parts of phenoxyethanol, and 1 part of foam stabilizer, add 10 parts of deionized water and stir to form component C; S4: Mix A, B, and C in sequence to obtain component D; S5: Adjust the pH of system D to 8.5, add an appropriate amount of deionized water to adjust to the target concentration; S6: Add xanthan gum and calcium lactate composition dropwise, stir to form a transparent high-viscosity gel, and complete the preparation of the fire extinguishing agent.

[0031] Comparative Example 1: Without using trimethyl phosphate, a system consisting only of emulsifiers, water, and inorganic particles was used to verify the performance differences under conditions without free radical inhibitors.

[0032] Preparation steps: S1: Mix 1 part of nano-aluminum hydroxide and 1 part of modified nano-silica, then add 10 parts of deionized water to form component A; S2: Mix 30 parts of OP-10 emulsifier directly with 20 parts of deionized water to obtain component B; S3: Prepare 10 parts of antifreeze, 1 part of fluorocarbon surfactant, 1 part of phenoxyethanol and 1 part of foam stabilizer, add 10 parts of deionized water, and stir to form component C; S4: Mix components A, B and C to obtain component D; S5: Adjust the pH to neutral with ammonia water, and add a small amount of deionized water to adjust the concentration; S6: Add xanthan gum-calcium lactate composite agent to form a preliminary gel, and obtain the comparative sample.

[0033] Comparative Example 2: This comparative example removes all inorganic fillers (aluminum hydroxide and silica), retaining only emulsifiers, antibacterial agents, and organic film-forming agents, to analyze the impact of the absence of inorganic insulating components on overall performance.

[0034] Preparation steps: S1: No component A added (no inorganic particles); S2: Mix 2 parts trimethyl phosphate with 30 parts OP-10, then add 20 parts deionized water to form component B; S3: Mix 10 parts antifreeze, 1 part fluorocarbon surfactant, 1.5 parts phenoxyethanol, 1 part foam stabilizer, and 10 parts water to form component C; S4: Combine B and C and stir evenly to form component D; S5: Adjust the pH to 8-9 and add water to the target viscosity; S6: Add xanthan gum and calcium lactate to form a colloidal structure, obtaining a fire extinguishing agent sample without inorganic reinforcing agents.

[0035] Performance testing Conductivity testing methods The ionic conductivity of the fire extinguishing agent samples was determined at room temperature using a standard laboratory conductivity meter. Before testing, the samples were thoroughly shaken and mixed, allowed to stand for 10 minutes, and then the supernatant was poured into a measuring battery for measurement. This method directly reflects whether the fire extinguishing agent provides electrical safety assurance for the lithium battery system during fire extinguishing; lower conductivity reduces the risk of leakage and short circuits.

[0036] Foaming performance test method The foaming ability of the extinguishing agent during actual spraying was simulated using mechanical stirring. The extinguishing agent sample was placed in a graduated cylinder and stirred for 30 seconds at a fixed speed. Immediately after stirring stopped, the foam height and remaining liquid height were observed to assess the foam volume growth capacity. The foam system was then allowed to stand, and the time required for the first noticeable collapse of the foam top was recorded to assess the stability of the foam structure. This test demonstrates the spread and adhesion time of the extinguishing agent when actually sprayed onto the surface of a lithium battery, and is particularly significant for its persistence in high-temperature flue gas environments.

[0037] Gel stability and pH response test methods The fire extinguishing agent sample was poured into a transparent cuvette and placed in a constant temperature environment for 24 hours. The presence of stratification, sedimentation, or collapse was observed to evaluate the stability of the three-dimensional gel network structure under static storage conditions at room temperature. Subsequently, the pH of the system was adjusted by adding acid or alkali dropwise, and changes such as transparency, disintegration, or structural compaction of the gel were observed to determine its pH responsiveness. This method was used to evaluate the adaptability and structural reversibility of the cross-linked gel network constructed using the xanthan gum-calcium lactate coordination system to environmental changes.

[0038] Cooling rate test method To simulate the high-temperature environment of lithium battery thermal runaway, a hot plate was used to heat aluminum powder to near the combustion temperature of a lithium battery, and an infrared thermometer was used to record its initial surface temperature. Pre-formulated extinguishing agent foam was then rapidly sprayed onto the hot aluminum powder surface, while the temperature change trend was continuously monitored with an infrared thermometer, recording the rapid temperature drop within the first 5 seconds after spraying. This test can evaluate the evaporative heat absorption capacity of the extinguishing agent foam and its fire suppression and cooling efficiency in high-temperature environments, and is an important means of measuring the extinguishing agent's ability to control heat diffusion.

[0039] Surface tension testing methods An automatic surface tension meter was used to determine the surface tension of the extinguishing agent solution using the pendant method. Samples were tested at room temperature. Lower surface tension values ​​indicate that the extinguishing agent spreads and adheres more easily to the burning surface, facilitating rapid fire coverage and inhibiting fire spread. This testing method was used to verify whether the synergistic effect of introduced fluorocarbon surfactants, emulsifiers, and other components effectively reduces interfacial energy, thereby improving the rapid wetting and reignition prevention performance of the extinguishing agent.

[0040] Table 1 Performance test results of low-conductivity, high-stability lithium battery-specific gel-type water-based fire extinguishing agent ; To comprehensively verify the overall performance advantages of the low-conductivity, high-stability lithium battery-specific gel-type water-based fire extinguishing agent of this invention in terms of electrical insulation, foam stability, cooling capacity, and surface spreadability, systematic tests were conducted on the samples prepared in Examples 1, 2, and 3, and Comparative Examples 1 and 2. The test items included foam conductivity, expansion ratio, liquid separation time, maximum cooling rate, and surface tension. The test results are shown in the table below. Figure 3 As shown.

[0041] As can be seen from the foam conductivity data, the foam conductivity of Examples 1-3 was controlled between 7.8 and 8.3 μS / cm, significantly lower than that of Comparative Example 1 (15.4 μS / cm) and Comparative Example 2 (22.8 μS / cm). This performance is attributed to the composite insulating framework composed of modified nano-silica aerogel and nano-aluminum hydroxide, whose high specific surface area and three-dimensional porous structure effectively restrict the migration path of electrolyte ions. Simultaneously, the aerogel, modified with high-temperature surfaces, is distributed in a stable hydrophobic state within the system, further reducing the possibility of ion concentration and the formation of conductive channels in the foam. The fact that this invention did not add traditional high-ion-content salt flame retardants is one of the important reasons for the significant reduction in conductivity.

[0042] Regarding foam expansion and stability, the expansion ratios of Examples 1-3 were 8.2, 9.1, and 10.0, respectively, significantly higher than those of Comparative Example 1 (6.5) and Comparative Example 2 (5.3). This superior foaming performance is attributed to the synergistic interfacial regulation between the emulsifier OP-10 and the fluorocarbon surfactant, which effectively reduces the gas-liquid interfacial tension and enhances the elasticity of the bubble film. In terms of liquid separation time, the examples consistently remained above 12.5 minutes, significantly better than the comparative examples (all less than 9 minutes). This indicates that the constructed pH-responsive gel structure forms a physical support network in the foam system, effectively locking in liquid, mitigating foam collapse due to gravity and water separation, and enhancing the foam layer's coverage and oxygen barrier sealing performance.

[0043] In terms of thermal response performance, the maximum cooling rates of Examples 1-3 reached 200, 213, and 232 °C / s, respectively, while those of Comparative Examples 1 and 2 were only 128 and 95 °C / s, respectively. This high thermal suppression efficiency mainly relies on the decomposition of trimethyl phosphate under high temperature conditions to generate phosphorus free radicals such as PO-. These intermediate products can rapidly combine with chain free radicals such as H+ and OH- during the combustion process, terminating the combustion chain reaction process. At the same time, the aerogel and nano-aluminum hydroxide absorb a large amount of heat energy during the decomposition process and form heat-insulating particles, forming an inert protective barrier on the surface of the fire source, effectively reducing the temperature propagation rate and preventing the thermal runaway of lithium batteries from spreading.

[0044] In the surface tension test, the foam tension of Examples 1 to 3 was controlled at 15.2 to 16.5 mN / m, which is lower than that of the comparative example (20.4 to 23.8 mN / m). This helps the foam to spread quickly, penetrate and tightly cover the shell of the lithium battery, improve the fire extinguishing coverage efficiency and prevent the risk of flammable vapor escape and reignition.

[0045] In summary, by constructing a multiphase synergistic network, this invention achieves foam stability, electrical insulation, and rapid thermal suppression without introducing any high-conductivity components. It systematically solves the common problems of high conductivity, foam instability, and poor adaptability to lithium battery fire extinguishing in water-based fire extinguishing agents, demonstrating excellent comprehensive fire extinguishing performance and application engineering feasibility.

Claims

1. A low-conductivity, high-stability gel-type water-based fire extinguishing agent specifically for lithium batteries, characterized in that, It contains the following raw materials in parts by weight: 1-3 parts modified nano-silica aerogel; 1-3 parts nano-aluminum hydroxide; 1-3 parts trimethyl phosphate; 20-35 parts emulsifier OP-10; 10-15 parts antifreeze; 0.5-1.5 parts fluorocarbon surfactant; 0.5-1.5 parts antibacterial agent phenoxyethanol; 0.5-2 parts foam stabilizer; 0.3-1.5 parts xanthan gum; 0.1-0.8 parts calcium lactate; 0.5-2 parts bentonite; 0.5-2 parts mica; 0.1-1 part regulator; and 40-60 parts deionized water.

2. The low-conductivity, high-stability gel-type water-based fire extinguishing agent for lithium batteries according to claim 1, characterized in that, The modified nano-silica aerogel comprises the following raw materials in parts by weight: 10-20 parts of tetraethyl orthosilicate; 60-100 parts of ethanol; 10-20 parts of deionized water; 0.5-1.5 parts of hydrochloric acid; 0.5-1.5 parts of ammonia; 2-6 parts of methyltriethoxysilane; and 1-3 parts of 3-(dioxophosphoric methylamino)propyltriethoxysilane. The concentration of the hydrochloric acid is 0.01 mol / L, and the volume fraction of the ammonia is 25%.

3. The low conductivity, high stability, gel-type water-based fire extinguishing agent for lithium batteries according to claim 1, characterized in that, The emulsifier OP-10 is octylphenol polyoxyethylene ether; the antifreeze is a mixture of ethylene glycol and glycerol in a mass ratio of 2:1 to 1:1; the fluorocarbon surfactant is a mixture of potassium hexafluorohexyl sulfonate and a perfluoroalkyl carboxylate-containing surfactant in a mass ratio of 1:2 to 1:3; the antibacterial agent is phenoxyethanol; and the regulator is a mixture of triethanolamine and sodium hydroxide solution in a mass ratio of 2:1 to 3:

1.

4. A low-conductivity, high-stability gel-type water-based fire extinguishing agent for lithium batteries according to claim 1 or 2, characterized in that, The preparation method of the modified nano-silica aerogel includes the following steps: (1) After mixing tetraethyl orthosilicate and ethanol evenly, add deionized water and hydrochloric acid and stir to carry out hydrolysis reaction to form a transparent sol; (2) Slowly add ammonia water to the transparent sol while continuing to stir; (3) Add methyltriethoxysilane and 3-(dioxophosphoric methylamino)propyltriethoxysilane in sequence; (4) After aging the reaction product, ethanol is added to perform multiple solvent replacements. (5) Drying to obtain a dry gel; (6) Heat treatment of the dry gel yields a modified nano silica aerogel with stable structure and synergistic regulation of surface functional groups.

5. The low-conductivity, high-stability gel-type water-based fire extinguishing agent for lithium batteries according to claim 4, characterized in that, In step (1), the hydrolysis reaction is carried out at a temperature of 25-35°C for 30-60 minutes and at a pH of 2.5-3.

5. In step (2), the polycondensation reaction is carried out at a pH of 8-9 and at a reaction time of 1-2 hours. In step (3), the surface modification reaction is carried out at a temperature of 20-30°C for 2-4 hours. In step (5), the drying temperature is 50-80°C and the drying time is 12-24 hours. In step (6), the heat treatment temperature is 600-800°C and the heat treatment time is 1-3 hours.

6. A method for preparing a low-conductivity, high-stability gel-type water-based fire extinguishing agent specifically for lithium batteries, wherein the low-conductivity, high-stability gel-type water-based fire extinguishing agent is as described in any one of claims 1 to 5, characterized in that... Includes the following steps: S1, Modified nano-silica aerogel and nano-aluminum hydroxide are added to deionized water and dispersed evenly under stirring to form the first dispersion; S2, after mixing trimethyl phosphate and emulsifier OP-10 evenly, add it to the first dispersion and continue stirring to form an emulsion system; S3, add antifreeze, fluorocarbon surfactant, antibacterial agent phenoxyethanol and foam stabilizer to the emulsion, stir and mix to form a homogeneous main liquid; S4. Add xanthan gum and calcium lactate to the main system liquid, and slowly add the regulator to adjust the pH. Continue stirring to promote the formation of gel structure. S5, after gel formation, add bentonite and mica, and stir thoroughly to improve system stability and adhesion performance; S6, add deionized water, and mix thoroughly again to obtain a low-conductivity, highly stable gel-type water-based fire extinguishing agent specifically for lithium batteries.

7. The low-conductivity, high-stability gel-type water-based fire extinguishing agent for lithium batteries according to claim 6, characterized in that, The temperature at which the first dispersion is formed in step S1 is 25–35°C.

8. The low-conductivity, high-stability gel-type water-based fire extinguishing agent for lithium batteries according to claim 6, characterized in that, In step S4, the pH of the gel formation is 6.5 to 7.5.

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