Gel fire extinguishing additive for inhibiting rekindling and preparation method and application thereof

Abstract

This invention belongs to the field of fire safety technology, and relates to a gel fire extinguishing additive for inhibiting reignition, its preparation method, and its application. The raw materials of the gel fire extinguishing additive include the following components in parts by weight: 1-5 parts of gelling agent, 1-4.5 parts of thickener, 2-5 parts of crosslinking agent, 1-3 parts of penetrant, 2-6 parts of flame retardant, and 3-5 parts of antifreeze agent; the gelling agent is selected from hydroxypropyl methylcellulose; the thickener is selected from chitosan and / or ethylene glycol chitosan; the crosslinking agent includes sodium tripolyphosphate and calcium nitrate. This invention provides a gel fire extinguishing additive with high-temperature rapid film formation, temperature-sensitive response, excellent adhesion, long-lasting cooling, reignition inhibition, and flame retardant protection functions through temperature-sensitive response and multifunctional synergistic design. It solves the problems of slow fire extinguishing, frequent reignition, poor adhesion, and poor environmental adaptability in existing lithium-ion battery fire extinguishing technologies, and has important application prospects and industrial promotion value.

Description

Technical Field

[0001] This invention belongs to the field of fire safety technology, and relates to a gel fire extinguishing additive that inhibits reignition, its preparation method, and its application. Background Technology

[0002] With the widespread application of lithium-ion batteries in new energy vehicles and energy storage systems, they are prone to thermal runaway and fires under conditions such as overcharging, short circuits, or mechanical damage. Current technologies primarily employ water-based, dry powder, and gaseous extinguishing agents to address these fires. Water-based extinguishing agents possess good cooling capabilities, and some deionized or insulating water-based systems exhibit low conductivity, meeting certain requirements for use in charged environments. However, these extinguishing agents are still in fluid form, with limited adhesion and retention capabilities, making them prone to leakage within complex battery structures and failing to form a durable and stable coating on the heat source surface, thus affecting continuous cooling and suppression of reignition. While dry powder extinguishing agents can quickly suppress open flames, they primarily rely on chemical suppression and lack sustained cooling capabilities, making it difficult to effectively reduce the internal temperature of the battery. Gaseous extinguishing agents mainly work through asphyxiation, and their ability to suppress the continuous exothermic reactions inside the battery is also relatively limited. In addition, although foam fire extinguishing systems can isolate air through covering, their foam structure is easily damaged under the high temperature and gas impact conditions caused by the thermal runaway of lithium-ion batteries, making it difficult to maintain stable coverage for a long time.

[0003] In recent years, gel-type fire extinguishing materials have been developed. By constructing a three-dimensional network structure using polymer components, they can significantly improve the adhesion and retention capacity of the extinguishing agent on the burning surface, thereby extending the residence time of moisture in high-temperature areas and enhancing the sustained cooling effect to some extent. Therefore, the gel system not only helps reduce the heat release rate but also forms a covering layer on the protected surface, isolating air and inhibiting the escape of flammable gases. However, existing gel fire extinguishing agents mostly focus on improving cooling performance through structural thickening; their rapid response capability, structural stability, and ability to inhibit reignition under high-temperature conditions still need further improvement. Especially during the thermal runaway of lithium-ion batteries, continuous heat release and gas impact can easily lead to damage or instability of the gel structure, thus affecting its long-term coverage and effectiveness.

[0004] Therefore, there is an urgent need to develop a multifunctional synergistic fire extinguishing system that can respond quickly and form a stable covering layer under high temperature conditions, while also possessing excellent moisture retention, good adhesion, and long-term ability to suppress reignition, in order to overcome the aforementioned shortcomings of existing technologies. Summary of the Invention

[0005] The main objective of this invention is to overcome the deficiencies in the prior art and provide a gel fire extinguishing additive for inhibiting reignition, its preparation method, and its application.

[0006] To achieve the above objectives, the specific technical solution is as follows: This invention provides a gel fire extinguishing additive that inhibits reignition, the raw materials of which include the following components in parts by weight: 1-5 parts gelling agent, 1-4.5 parts thickener, 2-5 parts crosslinking agent, 1-3 parts penetrant, 2-6 parts flame retardant, and 3-5 parts antifreeze; The gelling agent is selected from hydroxypropyl methylcellulose (HPMC); the thickener is selected from chitosan and / or ethylene glycol chitosan; the crosslinking agent includes sodium tripolyphosphate (STPP) and calcium nitrate.

[0007] This invention's gel fire extinguishing additive, when compounded with water, can be formulated into a temperature-sensitive gel fire extinguishing agent with characteristics such as rapid gelation, continuous cooling, and environmental friendliness. It is suitable for emergency response and thermal runaway prevention in lithium-ion battery fires. The temperature-sensitive skeleton hydroxypropyl methylcellulose used in this invention can rapidly respond to high temperatures in the early stages of lithium battery thermal runaway, quickly forming a covering film to isolate air and cover the heat source, achieving rapid suppression and thermal insulation of the flame, effectively blocking the combustion chain reaction. The three-dimensional network structure constructed by the thickeners chitosan and ethylene glycol chitosan enhances the adhesion and retention capacity of the gel on complex battery surfaces, allowing the fire extinguishing agent to remain on the heat source surface for a long time, achieving continuous cooling and reignition suppression. The crosslinking agents STPP and calcium nitrate form a multivalent cationic crosslinking network to assist crosslinking, improve the structural stability of the gel under high temperature and gas impact conditions, prevent the covering layer from cracking, and thus enhance the long-term protective capability of the fire extinguishing agent.

[0008] Furthermore, the raw materials of the gel fire extinguishing additive include 3 to 5 parts of functional additives, wherein the functional additives are selected from propylene glycol (PG).

[0009] The functional additive propylene glycol used in this invention is used to retain moisture, improve rheological properties, and lower the low-temperature freezing point.

[0010] Furthermore, the mass ratio of sodium tripolyphosphate (STPP) to calcium nitrate is (1-2):1.

[0011] The present invention uses a crosslinking agent with the above-mentioned mass ratio, resulting in a more uniform multivalent cationic crosslinking network structure. This ensures that the gel forming speed is adapted to the response requirements of lithium battery thermal runaway, while also achieving higher structural strength. Under the impact of high-speed airflow during thermal runaway, it is less prone to cracking or falling off, thus maintaining the integrity of the covering layer and ensuring long-term heat insulation and flame suppression effects. At the same time, it does not cause premature curing of the gel system due to excessive crosslinking, which would affect the fluidity of the extinguishing agent during storage and use.

[0012] Furthermore, the penetrant is fatty alcohol polyoxyethylene ether (AEO-9).

[0013] The present invention uses a penetrant, fatty alcohol polyoxyethylene ether AEO-9, which can enhance the penetration ability of the fire extinguishing agent into the gaps of the battery module and the surface of the heat source, ensuring that the gel uniformly covers hard-to-reach areas and improves the uniformity and reliability of fire extinguishing.

[0014] Furthermore, the flame retardant is selected from ammonium polyphosphate (APP) and / or ammonium nitrate (MAP); preferably composed of ammonium polyphosphate and ammonium nitrate; more preferably, the mass ratio of ammonium polyphosphate to ammonium nitrate is (1-2):1.

[0015] This invention utilizes the aforementioned flame retardant to form a heat-insulating char layer at high temperatures, while simultaneously inhibiting the combustion chain reaction, effectively preventing the risk of reignition after thermal runaway, and significantly improving battery fire extinguishing safety. Furthermore, the composite flame retardant formulated in the above proportions avoids the negative impact of excessive dosage of a single flame retardant on gel flowability and molding performance, balancing flame retardant efficiency with the performance of the extinguishing agent, and synergistically enhancing the suppression of lithium battery thermal runaway.

[0016] Further, the antifreeze is selected from propylene glycol (PG) and / or dipropylene glycol (DPG); preferably composed of propylene glycol and dipropylene glycol, more preferably the mass ratio of propylene glycol and dipropylene glycol is 1:(0.5-2).

[0017] The antifreeze agent used in this invention can ensure the fluidity and moisturizing properties of the system at low temperatures.

[0018] This invention also provides a method for preparing the above-mentioned gel fire extinguishing additive, comprising the following steps: (1) Dissolve the gelling agent in deionized water, let it stand to defoam, and obtain solution A; (2) Dissolve the thickener in deionized water, let it stand to defoam, and obtain solution B; (3) Mix solutions A and B with the crosslinking agent at room temperature to obtain solution C; (4) Mix the functional additives, penetrants, flame retardants, and antifreeze with solution C, let stand to defoam, dry, and pulverize.

[0019] The fire extinguishing gel prepared by this invention is in the form of a powdered solid, which has good storage stability and convenient transportation, significantly expanding its application possibilities in multiple scenarios.

[0020] Preferably, the gelling agent and thickener are dried at 65-75°C for 1-2 hours.

[0021] Further, in steps (1) and (2), the gelling agent and the thickener are dissolved in deionized water by stirring at 60-80°C for 1-2 hours, and the standing time is 20-24 hours.

[0022] Furthermore, in step (3), the stirring time is 1 to 2 hours; in step (4), the settling time is 12 to 24 hours.

[0023] Furthermore, in step (4), the drying is carried out under vacuum conditions at 60-80°C; preferably, the powder is sieved through a 100-mesh sieve after pulverization.

[0024] The present invention also provides a hydrogel fire extinguishing agent, comprising the above-mentioned hydrogel fire extinguishing additive or the hydrogel fire extinguishing additive prepared by the above-mentioned hydrogel fire extinguishing additive preparation method.

[0025] Furthermore, in the hydrogel fire extinguishing agent, the gel fire extinguishing additive accounts for 2 to 5% of the mass of the hydrogel fire extinguishing agent.

[0026] The gel fire extinguishing additive of this invention, when compounded with water, can be made into a temperature-sensitive gel fire extinguishing agent with characteristics such as rapid gelation, continuous cooling, and environmental friendliness. It is suitable for emergency treatment and thermal runaway prevention of lithium-ion battery fires. It is easy to use, requiring only a small amount to be effective, and has low cost and high application and promotion value.

[0027] Compared with the prior art, the present invention has the following significant advantages: This invention, through the design of a temperature-sensitive framework and polymer network structure, enables the gel fire extinguishing additive to rapidly thicken and form a stable covering layer in the early stages of lithium battery thermal runaway. This prolongs the residence time of moisture in high-temperature areas, significantly improving the sustained cooling effect and effectively isolating air and inhibiting the release of flammable gases. Simultaneously, by rationally selecting functional components such as thickeners, crosslinking agents, penetrants, and flame retardants, this invention achieves synergistic effects among the components, not only enhancing the high-temperature stability and moisture retention of the gel structure but also strengthening the long-term ability to inhibit reignition during thermal runaway. Furthermore, while ensuring rapid response and structural stability, this system also considers the adhesion and permeability to complex battery module surfaces, allowing the fire extinguishing agent to fully cover the battery surface and internal heat source areas, achieving efficient, safe, and reliable handling of thermal runaway fires in power batteries and energy storage batteries.

[0028] This invention provides a gel fire extinguishing additive with high-temperature rapid film formation, temperature-sensitive response, excellent adhesion, long-lasting cooling, suppression of reignition, and flame retardant protection functions through temperature-sensitive response and multi-functional synergistic design. It solves the problems of slow fire extinguishing, frequent reignition, poor adhesion, and poor environmental adaptability in existing lithium-ion battery fire extinguishing technologies, and has important application prospects and industrial promotion value. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in this invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below.

[0030] Figure 1 This is a diagram showing the gel state of the gel fire extinguishing additive solution D in Example 1 of the present invention. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with the embodiments of this invention. Obviously, the described embodiments are only some embodiments of this invention, not all embodiments. 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] The terms "preferred," "further preferred," and "more preferred" used in this invention, followed by technical features, constitute preferred embodiments of the invention in a specific aspect, but should not be construed as limiting the scope of protection. When the preferred definitions at each level are combined in a progressive relationship, the degree of preference increases progressively.

[0033] In this invention, the technical features described in an open-ended manner include both closed-ended technical solutions composed of the listed features and open-ended technical solutions that include the listed features.

[0034] In this invention, numerical ranges are involved. Unless otherwise specified, the numerical ranges are considered continuous and include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Furthermore, when the range refers to integers, it includes every integer between the minimum and maximum values ​​of the range. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are included.

[0035] The technical solution of the present invention will be described in detail below through embodiments and comparative examples. It should be noted that the following embodiments are only used to help understand the technical solution of the present invention and do not constitute any limitation on the scope of protection of the present invention.

[0036] Unless otherwise specified, specific techniques or conditions in the embodiments of this invention shall be performed in accordance with the techniques or conditions described in the literature in this field, or in accordance with the product instructions. Devices, instruments, reagents, etc., whose manufacturers are not specified are all conventional products that can be purchased through legitimate channels. All raw materials used in this invention are readily available in the domestic market.

[0037] Example 1 This embodiment provides a gel fire extinguishing additive and its preparation method, wherein the gel fire extinguishing additive is prepared from the following raw materials in the indicated mass percentages: 2% gelling agent, 2% thickener, 4% crosslinking agent, 4% propylene glycol, 2% penetrant AEO-9, 4% flame retardant, 4% antifreeze, balance deionized water; The gelling agent is hydroxypropyl methylcellulose, the thickener is chitosan, the crosslinking agent is sodium tripolyphosphate and calcium nitrate in a mass ratio of 1:1, the flame retardant is ammonium polyphosphate and ammonium nitrate in a mass ratio of 1:1, and the antifreeze agent is propylene glycol and dipropylene glycol in a mass ratio of 1:1.

[0038] This embodiment also provides a method for preparing the above-mentioned gel fire extinguishing additive, including the following steps: (1) Dry the gelling agent and thickener in an oven at 70°C for 1.5 hours, then remove them and place them in a vacuum drying oven for later use.

[0039] (2) Add the gelling agent to deionized water at 60℃ and stir for 2 hours. Let it stand at room temperature for 22 hours to remove bubbles and obtain solution A; (3) Add the thickener to deionized water, stir in a water bath at 75°C for 1.5 hours, and let stand at room temperature for 20 hours to remove bubbles, to obtain solution B; (4) After mixing solutions A and B, add a crosslinking agent and stir for 2 hours to obtain solution C; (5) Add propylene glycol, penetrant, flame retardant and antifreeze to solution C, stir for 2 hours, let stand for 24 hours to remove bubbles, and obtain solution D; (6) Place solution D in a vacuum drying oven at 70°C to dry, pulverize and pass through a 100-mesh sieve to obtain a powdered gel fire extinguishing additive.

[0040] Example 2 This embodiment provides a gel fire extinguishing additive and its preparation method, wherein the gel fire extinguishing additive is prepared from the following raw materials in the indicated mass percentages: 1.5% gelling agent, 3% thickener, 3% crosslinking agent, 3% propylene glycol, 1.5% penetrant AEO-9, 5% flame retardant, 3% antifreeze, balance deionized water; The gelling agent is hydroxypropyl methylcellulose, the thickener is ethylene glycol chitosan, the crosslinking agent is sodium tripolyphosphate and calcium nitrate in a mass ratio of 1:1, the flame retardant is ammonium polyphosphate and ammonium nitrate in a mass ratio of 1:1, and the antifreeze agent is propylene glycol and dipropylene glycol in a mass ratio of 1:1.

[0041] The preparation method of the fire extinguishing gel in this embodiment is the same as that in Example 1, and will not be repeated here.

[0042] Example 3 This embodiment provides a gel fire extinguishing additive and its preparation method, wherein the gel fire extinguishing additive is prepared from the following raw materials in the indicated mass percentages: 1.0% gelling agent, 4.5% thickener, 5% crosslinking agent, 2.5% propylene glycol, 2% penetrant AEO-9, 6% flame retardant, 5% antifreeze, balance deionized water; The gelling agent is hydroxypropyl methylcellulose, the thickener is chitosan and ethylene glycol chitosan in a mass ratio of 2:1, the crosslinking agent is sodium tripolyphosphate and calcium nitrate in a mass ratio of 1:1, the flame retardant is ammonium polyphosphate and ammonium nitrate in a mass ratio of 1:1, and the antifreeze agent is propylene glycol and dipropylene glycol in a mass ratio of 1:1.

[0043] The preparation method of the fire extinguishing gel in this embodiment is the same as that in Example 1, and will not be repeated here.

[0044] Example 4 This embodiment provides a gel fire extinguishing additive and its preparation method. Compared with Example 1, the only difference is the composition of the fire extinguishing gel, specifically: the gelling agent is 5%.

[0045] Example 5 This embodiment provides a gel fire extinguishing additive and its preparation method. Compared with Embodiment 2, the only difference is the composition of the fire extinguishing gel. Specifically, the flame retardant is 6%, and the flame retardant is ammonium polyphosphate and ammonium nitrate in a mass ratio of 2:1.

[0046] Example 6 This embodiment provides a gel fire extinguishing additive and its preparation method. Compared with Embodiment 3, the only difference is the composition of the fire extinguishing gel. Specifically, the gelling agent is 3% and the flame retardant is ammonium polyphosphate and ammonium nitrate in a mass ratio of 2:1.

[0047] Comparative Example 1 Novec 1230 is a commercially available perfluorohexanone fire extinguishing agent.

[0048] Comparative Example 2 Deionized water.

[0049] Comparative Example 3 This embodiment provides a gel fire extinguishing additive and its preparation method. Compared with Example 2, the only difference is the composition of the fire extinguishing gel. Specifically, ethylene glycol chitosan is replaced with chitosan of equal mass percentage.

[0050] Comparative Example 4 This embodiment provides a gel fire extinguishing additive and its preparation method. Compared with Example 2, the only difference is the composition of the fire extinguishing gel. Specifically, ethylene glycol chitosan is replaced with an equal mass percentage of carboxymethyl chitosan.

[0051] Comparative Example 5 This embodiment provides a gel fire extinguishing additive and its preparation method. Compared with Example 1, the only difference is the composition of the fire extinguishing gel. Specifically, the crosslinking agent is sodium tripolyphosphate and does not contain calcium nitrate.

[0052] Comparative Example 6 This embodiment provides a gel fire extinguishing additive and its preparation method. Compared with Example 1, the only difference is the composition of the fire extinguishing gel. Specifically, the crosslinking agent is sodium tripolyphosphate and calcium nitrate in a mass ratio of 3:1.

[0053] Comparative Example 7 This embodiment provides a gel fire extinguishing additive and its preparation method. Compared with Example 5, the only difference is the composition of the fire extinguishing gel. Specifically, the flame retardant is ammonium polyphosphate and does not contain ammonium nitrate.

[0054] Comparative Example 8 This embodiment provides a gel fire extinguishing additive and its preparation method. Compared with Example 6, the only difference is the composition of the fire extinguishing gel. Specifically, the mass ratio of ammonium polyphosphate to ammonium nitrate is 1:2.

[0055] The powdered temperature-sensitive fire extinguishing gels from each embodiment and Comparative Example 1 were added to water and stirred until homogeneous to obtain the fire extinguishing agent, and then its performance was tested.

[0056] Viscosity: The rheological properties of the system were characterized using an NDJ-8S rotational viscometer (25 ± 0.5 ℃). During the test, rotor No. 1 was used at a rotational speed of 60 rpm, and measurements were taken under stable shear conditions. The average value of the readings when they reached a stable state with minimal fluctuations was taken as the final viscosity result, expressed in mPa·s.

[0057] Surface tension: Measured using a BAY-101 automatic surface / interface tension meter (Wilhelmy plate method), obtained by the change in wetting force between the platinum plate and the liquid interface. The basic relationship can be expressed as γ = F / L, where F is the force and L is the contact perimeter.

[0058] Conductivity: The DDSJ-308F conductivity meter (DJS-1D electrode) was used to measure the conductivity at a constant temperature of 25 ℃. Before measurement, the electrode was calibrated with a standard conductivity solution. During the test, the electrode was completely immersed in the solution to be tested and allowed to stand for about 5 min. After the signal stabilized, the value was read to characterize the ionic strength and electrolyte dissolution behavior of the system.

[0059] pH value: The pH value was measured using a PHS-3C precision pH meter (composite electrode). Before the test, three-point calibration was performed using standard buffer solutions (pH 4.00, 6.86, and 9.18). During the measurement, the electrode was immersed in the solution and left to stand for about 5 minutes. After the potential response stabilized, the value was read to reflect the changes in the acidity and alkalinity of the system and the degree of acidification caused by HF generation.

[0060] Application Example 1 The powdered gel fire extinguishing additives of each embodiment and Comparative Examples 3-8 were added to water and stirred evenly to obtain a fire extinguishing agent with a mass concentration of 3%; Comparative Example 1 used commercially available lithium-ion battery water-based fire extinguishing agent and Comparative Example 2 used deionized water, which can be used directly. The results are shown in Table 1.

[0061] Table 1. Indicators

[0062] Application Example 2 The powdered gel fire extinguishing additives from each embodiment and Comparative Examples 3-8 were added to water and stirred until homogeneous to obtain a fire extinguishing agent with a mass concentration of 4%. The commercially available lithium-ion battery water-based fire extinguishing agent of Comparative Example 1 and the deionized water of Comparative Example 2 can be used directly. The results are shown in Table 2.

[0063] Table 2 Indicators

[0064] Application Example 3 The powdered gel fire extinguishing additives of each embodiment and Comparative Examples 3-8 were added to water and stirred evenly to obtain a fire extinguishing agent with a mass concentration of 5%. The commercially available lithium-ion battery water-based fire extinguishing agent of Comparative Example 1 and the deionized water of Comparative Example 2 can be used directly. The results are shown in Table 3.

[0065] Table 3 Indicators

[0066] The fire extinguishing gel of this invention, when mixed with water, can be made into a high-adhesion, anti-sagging temperature-sensitive gel fire extinguishing agent with characteristics such as rapid gelation, continuous cooling, and environmental friendliness, and is easy to use.

[0067] As can be seen from the data in Tables 1 to 3, the fire extinguishing gel prepared in this invention, when combined with water, requires only 3-5% addition to obtain a high-performance temperature-sensitive gel fire extinguishing agent. Its overall performance is significantly superior to commercially available lithium-ion battery water-based fire extinguishing agents, deionized water, and the comparative proportions. Its effects are mainly reflected in the following aspects: (1) The extinguishing agent of the present invention has excellent wetting and penetrating properties. The surface tension of the extinguishing agents obtained in Examples 1 to 6 is always maintained between 27.2 and 27.9 mN / m, which is significantly lower than that of deionized water (72.3 mN / m), enabling it to wet the battery surface more quickly and penetrate into the thermal runaway area, thereby improving cooling efficiency and extinguishing efficiency.

[0068] (2) The extinguishing agent of the present invention has suitable rheological properties. As the amount of extinguishing gel added increases from 3% to 5%, the viscosity of the system gradually increases from 2.46-4.51 mPa·s to 3.81-5.98 mPa·s. While ensuring good spray performance, it improves the adhesion ability of the extinguishing agent to the battery surface, enabling the extinguishing agent to continuously cover the high-temperature area and prevent it from being lost, thereby prolonging the cooling time and enhancing the continuous cooling effect. Among them, the adhesion strength of the gel system obtained in Comparative Example 5 decreased, the gel network structure was relatively loose, and the high-temperature continuous coverage ability was insufficient; the gel system obtained in Comparative Example 6 showed local flocculation, decreased uniformity, and reduced adhesion effect to the battery surface.

[0069] (3) The fire extinguishing agent of the present invention has a fast fire extinguishing speed and strong cooling ability. At a dosage of 3%, the fire extinguishing time of Examples 1-6 is only 2-4 s, while commercially available fire extinguishing agents and deionized water require 145 s and 134 s, respectively; each comparative example still requires 7-12 s. As the dosage increases to 4% and 5%, all examples can complete the fire extinguishing within 2 s, while the comparative examples still require 4-8 s, indicating that the present invention significantly improves the initial fire extinguishing efficiency.

[0070] (4) The fire extinguishing agent of the present invention has excellent continuous cooling ability. After continuous fire extinguishing for 4 minutes, the battery temperature of Examples 1 to 6 was significantly lower than that of the comparative examples. Among them, at the addition amount of 5%, the battery temperature of Examples 1 was only 68.4-81.3 ℃, which was significantly lower than the 128.7 ℃ of commercially available fire extinguishing agents, the 159.6 ℃ of deionized water, and the 81.7-97.6 ℃ of the comparative examples. The fire extinguishing additive of Example 6 was a homogeneous gel, and its adhesion and free radical capture ability were at a balance point, resulting in the best cooling effect. After continuous fire extinguishing, the temperature was only 68.4 ℃, indicating that the present invention can effectively reduce the battery temperature and continuously suppress the development of thermal runaway.

[0071] (5) The fire extinguishing agent of the present invention can effectively suppress reignition. Regardless of the addition amount of 3%, 4% or 5%, no reignition occurred in Examples 1 to 6 after 30 minutes of ignition; while commercially available fire extinguishing agents, deionized water and all comparative examples showed varying degrees of reignition, indicating that the present invention can not only quickly extinguish open flames, but also continuously reduce battery temperature and prevent heat accumulation from causing secondary thermal runaway. Among them, the fire extinguishing additive obtained in Example 5 is a homogeneous gel, which has the strongest ability to capture combustion free radicals, that is, the strongest fire extinguishing ability and long-term non-reignition. The fire extinguishing agent obtained in Comparative Example 3 shows a decrease in the uniformity of the gel film formed under high temperature conditions, a weakening of adhesion, a shortening of the battery surface coverage time, and a reduction in the ability to inhibit reignition. Although the fire extinguishing agent obtained in Comparative Example 4 has a certain gelling ability, the stability of the gel structure at high temperature is insufficient, the integrity of the coating is poor, and the continuous fire suppression ability is lower than that of Example 2. The fire extinguishing agent obtained in Comparative Example 7 has a certain flame retardant effect, but its ability to continuously suppress combustible gases during thermal runaway is insufficient, and the reignition phenomenon is more obvious. The fire extinguishing agent obtained in Comparative Example 8 shows a decrease in the ability to form char at high temperature, a decrease in the thermal stability of the gel layer, and a significant weakening of the reignition suppression effect.

[0072] (6) The fire extinguishing agent of the present invention has excellent wall-mounting and liquid-retaining properties. After the fire extinguishing is stopped, the agents in Examples 1 to 6 can stably adhere to the battery surface and continue to cool down, while commercially available fire extinguishing agents and deionized water cannot adhere to the battery surface, and each comparative example has only a small amount of residue, making it difficult to form a continuous covering layer. The temperature-sensitive gel formed by the present invention can firmly adhere to the surface of the high-temperature battery, continuously lock in water and retain moisture, reduce evaporation loss, achieve long-term cooling, and improve the thermal management capability after fire extinguishing.

[0073] In summary, the fire extinguishing gel prepared by this invention requires only a small amount of addition to significantly reduce the surface tension of the fire extinguishing agent, imparting suitable viscosity and excellent wall adhesion properties to the system. This achieves comprehensive advantages such as rapid fire extinguishing, continuous cooling, effective prevention of reignition, and long-term covering and cooling. This fully demonstrates that the fire extinguishing gel of this invention has excellent properties such as rapid gelation, high adhesion, anti-sagging, continuous cooling, and green environmental protection, and can meet the application requirements of rapid, efficient, and safe fire extinguishing of lithium-ion battery fires.

[0074] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A gel fire extinguishing additive for inhibiting reignition, characterized in that, The raw materials consist of the following components in parts by weight: 1-5 parts gelling agent, 1-4.5 parts thickener, 2-5 parts crosslinking agent, 1-3 parts penetrant, 2-6 parts flame retardant, and 3-5 parts antifreeze; The gelling agent is selected from hydroxypropyl methylcellulose; the thickener is selected from chitosan and / or ethylene glycol chitosan; the crosslinking agent includes sodium tripolyphosphate and calcium nitrate.

2. The gel fire extinguishing additive according to claim 1, characterized in that, The raw materials include 3 to 5 parts of functional additives, wherein the functional additives are selected from propylene glycol.

3. The gel fire extinguishing additive according to claim 1 or 2, characterized in that, The mass ratio of sodium tripolyphosphate to calcium nitrate is (1-2):

1.

4. The gel fire extinguishing additive according to claim 1 or 2, characterized in that, The penetrant is fatty alcohol polyoxyethylene ether.

5. The gel fire extinguishing additive according to claim 3, characterized in that, The flame retardant is selected from ammonium polyphosphate and / or ammonium nitrate; preferably it is composed of ammonium polyphosphate and ammonium nitrate; more preferably the mass ratio of ammonium polyphosphate and ammonium nitrate is (1-2):

1.

6. The gel fire extinguishing additive according to claim 4, characterized in that, The antifreeze is selected from propylene glycol and / or dipropylene glycol; preferably composed of propylene glycol and dipropylene glycol, more preferably the mass ratio of propylene glycol and dipropylene glycol is 1:(0.5-2).

7. A method for preparing a gel fire extinguishing additive as described in any one of claims 1 to 6, characterized in that, Includes the following steps: (1) Dissolve the gelling agent in deionized water, let it stand to defoam, and obtain solution A; (2) Dissolve the thickener in deionized water, let it stand to defoam, and obtain solution B; (3) Mix solutions A and B with the crosslinking agent at room temperature to obtain solution C; (4) Mix the functional additives, penetrants, flame retardants, and antifreeze with solution C, let stand to defoam, dry, and pulverize.

8. The method for preparing the gel fire extinguishing additive according to claim 7, characterized in that, In steps (1) and (2), the gelling agent and thickener are dissolved in deionized water by stirring at 60-80°C for 1-2 hours, and the standing time is 20-24 hours. And / or, in step (4), the drying is carried out under vacuum conditions at 60-80°C; preferably, the powder is sieved through a 100-mesh sieve after pulverization.

9. A hydrogel fire extinguishing agent, comprising the hydrogel fire extinguishing additive according to any one of claims 1 to 6 or the hydrogel fire extinguishing additive prepared by any one of claims 7 to 8.

10. The hydrogel fire extinguishing agent according to claim 9, characterized in that, The gel fire extinguishing additive is 3 to 5% of the mass of the hydrogel fire extinguishing agent.

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