Preparation method of environment-friendly lithium battery fire extinguishing agent based on nanofiber gel

Abstract

The invention discloses a preparation method of an environment-friendly lithium battery fire extinguishing agent based on nanofiber gel, and relates to the technical field of fire extinguishing. When the environment-friendly lithium battery fire extinguishing agent is prepared, nano sodium carboxymethyl cellulose reacts with N-isopropylacrylamide and N, N-methylene bisacrylamide to prepare semi-interpenetrating network hydrogel; the semi-interpenetrating network hydrogel and calcium lactate are cross-linked, and nano sodium carboxymethyl cellulose hydrogel is prepared; and mixing and stirring the nano sodium carboxymethyl cellulose hydrogel, the modified silicon carbide and a flame retardant to prepare the environment-friendly lithium battery fire extinguishing agent. The prepared environment-friendly lithium battery fire extinguishing agent has good fire extinguishing performance.

Description

Technical Field

[0001] This invention relates to the field of fire extinguishing technology, specifically to a method for preparing an environmentally friendly lithium battery fire extinguishing agent based on nanofiber gel. Background Technology

[0002] Lithium batteries are widely used in electronics, electric vehicles, aerospace and other fields due to their high energy density and environmental friendliness. However, in recent years, lithium battery fires have occurred frequently, and extinguishing them is difficult. This is because the temperature is very high after the battery catches fire; the thermal runaway propagates rapidly after combustion, easily igniting adjacent batteries and other flammable materials, leading to subsequent combustion or even explosion; even after the open flame is extinguished, chemical reactions still occur inside the lithium battery, generating flammable gases, requiring continued cooling measures to suppress the internal reactions and prevent reignition. Therefore, it is essential to develop an environmentally friendly lithium battery fire extinguishing agent that can effectively combat lithium battery fires. Summary of the Invention

[0003] The purpose of this invention is to provide a method for preparing an environmentally friendly lithium battery fire extinguishing agent based on nanofiber gel, so as to solve the problems existing in the prior art.

[0004] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0005] A method for preparing an environmentally friendly lithium battery fire extinguishing agent based on nanofiber gel, wherein the environmentally friendly lithium battery fire extinguishing agent is prepared by mixing and stirring modified silicon carbide, nano-carboxymethyl cellulose sodium hydrogel and flame retardant;

[0006] As an optimization, the modified silicon carbide is prepared by reacting silicon carbide with dodecyltriethoxysilane;

[0007] As an optimization, the nano-carboxymethyl cellulose sodium hydrogel is prepared by reacting nano-carboxymethyl cellulose sodium, N-isopropylacrylamide, and N,N-methylenebisacrylamide to obtain a semi-interpenetrating network hydrogel, which is then crosslinked with calcium lactate.

[0008] As an optimization, the flame retardant is prepared by reacting 2,4,6-tris(4-aminophenyl)-1,3,5-triazine and 2,5-dihydroxyterephthalaldehyde with a Schiff base reaction, followed by reaction with dimethyl chlorophosphate.

[0009] As an optimization, the preparation method of the environmentally friendly lithium battery fire extinguishing agent based on nanofiber gel includes the following preparation steps:

[0010] (1) Under a nitrogen atmosphere, nano-carboxymethyl cellulose sodium, N-isopropylacrylamide, N,N-methylenebisacrylamide, and deionized water were mixed evenly at a mass ratio of 1:(8-10):(0.08-0.1):(30-40). Ammonium persulfate and tetramethylethylenediamine (0.2-0.4 times the mass of nano-carboxymethyl cellulose sodium) were added. The mixture was stirred at 200-300 r / min at 2-4℃ for 20-24 h and then allowed to stand at 20-30℃ for 40-48 h to obtain a semi-interpenetrating network hydrogel. The semi-interpenetrating network hydrogel and 2wt% calcium lactate aqueous solution were mixed evenly at a mass ratio of 1:(0.6-0.8). The mixture was stirred at 2000-4000 rpm at room temperature for 10-12 min to obtain nano-carboxymethyl cellulose sodium hydrogel.

[0011] (2) Mix modified silicon carbide, nano carboxymethyl cellulose sodium hydrogel and flame retardant at a mass ratio of 1:(10~15):(0.2~0.3) until uniform, stir at a speed of 2000~4000rpm for 6~8min, and cool naturally to room temperature to obtain an environmentally friendly lithium battery fire extinguishing agent.

[0012] As an optimization, the preparation process of the nano-carboxymethyl cellulose sodium in step (1) is as follows: add the sodium carboxymethyl cellulose aqueous solution into a high-pressure homogenizer, homogenize it 1 to 3 times under the condition of 30 to 40 MPa, and then homogenize it once at 130 to 140 MPa to obtain nano-carboxymethyl cellulose sodium.

[0013] As an optimization, the sodium carboxymethyl cellulose aqueous solution is prepared by uniformly mixing sodium carboxymethyl cellulose and deionized water at a mass ratio of 1:(15-20).

[0014] As an optimization, the nozzle model of the high-pressure homogenizer is D8.

[0015] As an optimization, the preparation process of modified silicon carbide in step (2) is as follows: dodecyltriethoxysilane and deionized water are mixed evenly at a mass ratio of 1:(1.8-2.2), silicon carbide with a mass of 0.2-0.4 times that of dodecyltriethoxysilane and anhydrous ethanol with a mass of 5-7 times that of dodecyltriethoxysilane are added and mixed evenly. The mixture is stirred at 70-80°C and 200-300 r / min for 3-4 h, centrifuged at 8000-10000 rpm for 10-12 min, the precipitate is washed 2-4 times with anhydrous ethanol, and vacuum dried at 60-70°C for 4-6 h to obtain modified silicon carbide.

[0016] As an optimization, the preparation process of the flame retardant in step (2) is as follows: Under a nitrogen atmosphere, covalent organic framework, triethylamine, potassium carbonate, and tetrahydrofuran are mixed evenly in a mass ratio of 1:(0.4-0.5):(0.5-0.6):(10-15). At room temperature, 1.6-1.8 times the mass of covalent organic framework dimethyl chlorophosphate is added dropwise at a uniform rate over 30 minutes. The mixture is stirred at 55-65°C and 200-300 r / min for 10-12 hours. The mixture is then filtered and washed 2-4 times with deionized water. Finally, it is vacuum dried at 80-90°C for 20-24 hours to obtain the flame retardant.

[0017] As an optimization, the preparation process of the covalent organic framework is as follows: 2,4,6-tris(4-aminophenyl)-1,3,5-triazine, 2,5-dihydroxyterephthalaldehyde, and acetonitrile are mixed evenly at a mass ratio of 1:(0.8-0.9):(20-30), and sonicated for 30 min. Then, 40-50 times the mass of glacial acetic acid of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine is added and mixed evenly. The mixture is sonicated for 1-3 min, and allowed to stand at room temperature for 24-36 h. The mixture is then centrifuged at 8000-10000 rpm for 10-12 min. The resulting precipitate is washed 2-4 times each with tetrahydrofuran and anhydrous ethanol, and then vacuum dried at 60-70℃ for 22-24 h to obtain the covalent organic framework.

[0018] As an optimization, the viscosity of the sodium carboxymethyl cellulose is 800–1200 mPa·s, and it was purchased from Jiangsu Puleisi Biotechnology Co., Ltd.

[0019] As an optimization, the average particle size of the silicon carbide is 30-50 nm, and it was purchased from Shanghai Xiaohuang Nanotechnology Co., Ltd.

[0020] Compared with the prior art, the beneficial effects achieved by the present invention are:

[0021] In preparing an environmentally friendly lithium battery fire extinguishing agent based on nanofiber gel, this invention involves mixing sodium carboxymethyl cellulose with deionized water and adding it to a high-pressure homogenizer to obtain nano-sodium carboxymethyl cellulose; reacting nano-sodium carboxymethyl cellulose, N-isopropylacrylamide, and N,N-methylenebisacrylamide to obtain a semi-interpenetrating network hydrogel, which is then crosslinked with calcium lactate to obtain nano-sodium carboxymethyl cellulose hydrogel; reacting dodecyltriethoxysilane and silicon carbide to obtain modified silicon carbide; reacting 2,4,6-tris(4-aminophenyl)-1,3,5-triazine and 2,5-dihydroxyterephthalaldehyde with a Schiff base reaction to obtain a covalent organic framework, which is then reacted with dimethyl chlorophosphate to obtain a flame retardant; and mixing and stirring the modified silicon carbide, nano-sodium carboxymethyl cellulose hydrogel, and flame retardant to obtain the environmentally friendly lithium battery fire extinguishing agent.

[0022] First, sodium carboxymethyl cellulose (CMC) was mixed with deionized water and added to a high-pressure homogenizer to obtain nano-sodium CMC. Then, a semi-interpenetrating network hydrogel was prepared by reacting the nano-sodium CMC, N-isopropylacrylamide, and N,N-methylenebisacrylamide. Using N,N-methylenebisacrylamide as a crosslinking agent, it crosslinked with N-isopropylacrylamide to form the semi-interpenetrating network hydrogel. This hydrogel contains a large amount of water, which absorbs a significant amount of heat during evaporation, thus lowering the temperature of the burning material. Simultaneously, at high temperatures, the semi-interpenetrating network hydrogel is in a gel state with a certain viscosity, allowing it to adhere to the surface of the burning material, isolating the internal combustible gas from oxygen and reducing the possibility of reignition. Finally, the semi-interpenetrating network hydrogel was crosslinked with calcium lactate to obtain nano-sodium CMC hydrogel. The carboxylate ions crosslink with calcium ions to form a three-dimensional network structure hydrogel, improving the water retention capacity of the hydrogel and thus enhancing the fire extinguishing performance of the environmentally friendly lithium battery fire extinguishing agent.

[0023] Secondly, modified silicon carbide was prepared by reacting dodecyltriethoxysilane with silicon carbide. The modified silicon carbide exhibits superhydrophobic properties and good thermal conductivity, enabling it to quickly dissipate heat generated during combustion, reduce the temperature of the burning material, and decrease the possibility of reignition, thereby enhancing the fire extinguishing performance of the environmentally friendly lithium battery fire extinguishing agent. Furthermore, a covalent organic framework was prepared by reacting 2,4,6-tris(4-aminophenyl)-1,3,5-triazine and 2,5-dihydroxyterephthalaldehyde with a Schiff base reaction. The framework is then reacted with dimethyl chlorophosphate to prepare a flame retardant. The amino group on 2,4,6-tris(4-aminophenyl)-1,3,5-triazine reacts with the aldehyde group on 2,5-dihydroxyterephthalaldehyde to form a Schiff base reaction, forming a covalent organic framework. This framework is then reacted with dimethyl chlorophosphate to introduce phosphorus into the covalent organic framework. This phosphorus, along with the nitrogen element of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine, synergistically retards the flame, reduces the possibility of reignition, and enhances the fire extinguishing performance of the environmentally friendly lithium battery fire extinguishing agent.

[0024] Finally, an environmentally friendly lithium battery fire extinguishing agent was prepared by mixing modified silicon carbide, nano-carboxymethyl cellulose sodium hydrogel, and flame retardant. By utilizing the hydrophobicity of modified silicon carbide, a gel dry water fire extinguishing agent was prepared by mixing it with nano-carboxymethyl cellulose sodium hydrogel and flame retardant under stirring conditions. This improved water retention and enhanced the fire extinguishing performance of the environmentally friendly lithium battery fire extinguishing agent. At the same time, the dry water material has good fluidity and dispersibility and can be used in dry powder fire extinguishers. Detailed Implementation

[0025] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0026] Example 1:

[0027] A method for preparing an environmentally friendly lithium battery fire extinguishing agent based on nanofiber gel includes the following preparation steps:

[0028] (1) Sodium carboxymethyl cellulose and deionized water were mixed evenly at a mass ratio of 1:15 to obtain an aqueous solution of sodium carboxymethyl cellulose; the aqueous solution of sodium carboxymethyl cellulose was added to a high-pressure homogenizer and homogenized once at 30 MPa, and then homogenized once at 130 MPa to obtain nano-sodium carboxymethyl cellulose; under a nitrogen atmosphere, nano-sodium carboxymethyl cellulose, N-isopropylacrylamide, N,N-methylenebisacrylamide, and deionized water were mixed at a mass ratio of 1:8:0.08:30. The mixture was stirred evenly, and 0.2 times the mass of sodium carboxymethyl cellulose nanoparticles and 0.4 times the mass of sodium carboxymethyl cellulose nanoparticles and tetramethylethylenediamine were added. The mixture was stirred at 200 r / min for 20 h at 2 °C and then allowed to stand at 20 °C for 40 h to obtain a semi-interpenetrating network hydrogel. The semi-interpenetrating network hydrogel and 2 wt% calcium lactate aqueous solution were mixed evenly at a mass ratio of 1:0.6 and stirred at 2000 rpm for 10 min at room temperature to obtain sodium carboxymethyl cellulose nanoparticles hydrogel.

[0029] (2) Dodecyltriethoxysilane and deionized water were mixed evenly at a mass ratio of 1:1.8. Silicon carbide with a mass of 0.2 times that of dodecyltriethoxysilane and anhydrous ethanol with a mass of 5 times that of dodecyltriethoxysilane were added and mixed evenly. The mixture was stirred at 70°C and 200 r / min for 3 h. The mixture was then centrifuged at 8000 rpm for 10 min. The precipitate was washed twice with anhydrous ethanol and dried under vacuum at 60°C for 4 h to obtain modified silicon carbide.

[0030] (3) Mix 2,4,6-tris(4-aminophenyl)-1,3,5-triazine, 2,5-dihydroxyterephthalaldehyde, and acetonitrile at a mass ratio of 1:0.8:20 until homogeneous, sonicate for 30 min, add glacial acetic acid at 40 times the mass of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine and mix until homogeneous, sonicate for 1 min, let stand at room temperature for 24 h, centrifuge at 8000 rpm for 10 min, and separate the precipitate by rehydration with tetrahydrofuran and anhydrous ethanol. The covalent organic framework was prepared by washing twice and vacuum drying at 60℃ for 22h. Under a nitrogen atmosphere, the covalent organic framework, triethylamine, potassium carbonate, and tetrahydrofuran were mixed evenly in a mass ratio of 1:0.4:0.5:10. At room temperature, 1.6 times the mass of dimethyl chlorophosphate of the covalent organic framework was added dropwise over 30min. The mixture was stirred at 55℃ and 200r / min for 10h. The mixture was filtered and washed twice with deionized water, and then vacuum dried at 80℃ for 20h to obtain the flame retardant.

[0031] (4) The modified silicon carbide, nano carboxymethyl cellulose sodium hydrogel and flame retardant are mixed evenly at a mass ratio of 1:10:0.2, stirred at 2000 rpm for 6 minutes, and naturally cooled to room temperature to obtain an environmentally friendly lithium battery fire extinguishing agent.

[0032] Example 2:

[0033] A method for preparing an environmentally friendly lithium battery fire extinguishing agent based on nanofiber gel includes the following preparation steps:

[0034] (1) Sodium carboxymethyl cellulose and deionized water were mixed evenly at a mass ratio of 1:18 to obtain an aqueous solution of sodium carboxymethyl cellulose; the aqueous solution of sodium carboxymethyl cellulose was added to a high-pressure homogenizer and homogenized twice at 35 MPa, and then homogenized once at 135 MPa to obtain nano-sodium carboxymethyl cellulose; under a nitrogen atmosphere, nano-sodium carboxymethyl cellulose, N-isopropylacrylamide, N,N-methylenebisacrylamide, and deionized water were mixed at a mass ratio of 1:9:0.09:35. The mixture was homogeneous, and ammonium persulfate (0.3 times the mass of sodium carboxymethyl cellulose nanoparticles) and tetramethylethylenediamine (0.5 times the mass of sodium carboxymethyl cellulose nanoparticles) were added. The mixture was stirred at 250 r / min for 22 h at 3 °C and then allowed to stand at 25 °C for 44 h to obtain a semi-interpenetrating network hydrogel. The semi-interpenetrating network hydrogel and 2 wt% calcium lactate aqueous solution were mixed homogeneously at a mass ratio of 1:0.7 and stirred at 3000 rpm for 11 min at room temperature to obtain sodium carboxymethyl cellulose nanoparticle hydrogel.

[0035] (2) Dodecyltriethoxysilane and deionized water were mixed evenly at a mass ratio of 1:2. Silicon carbide with a mass of 0.3 times that of dodecyltriethoxysilane and anhydrous ethanol with a mass of 6 times that of dodecyltriethoxysilane were added and mixed evenly. The mixture was stirred at 75°C and 250 r / min for 3.5 h. The mixture was then centrifuged at 9000 rpm for 11 min. The precipitate was washed three times with anhydrous ethanol and dried under vacuum at 65°C for 5 h to obtain modified silicon carbide.

[0036] (3) Mix 2,4,6-tris(4-aminophenyl)-1,3,5-triazine, 2,5-dihydroxyterephthalaldehyde, and acetonitrile at a mass ratio of 1:0.85:25 until homogeneous, sonicate for 30 min, add glacial acetic acid at 45 times the mass of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine and mix until homogeneous, sonicate for 2 min, let stand at room temperature for 30 h, centrifuge at 9000 rpm for 11 min, and wash the precipitate with tetrahydrofuran and anhydrous ethanol respectively. The covalent organic framework was prepared by washing three times and then vacuum drying at 65℃ for 23 hours. Under a nitrogen atmosphere, the covalent organic framework, triethylamine, potassium carbonate, and tetrahydrofuran were mixed evenly at a mass ratio of 1:0.45:0.55:13. At room temperature, 1.7 times the mass of dimethyl chlorophosphate was added dropwise over 30 minutes. The mixture was stirred at 60℃ and 250 r / min for 11 hours. The mixture was filtered and washed three times with deionized water. The mixture was then vacuum dried at 85℃ for 22 hours to obtain the flame retardant.

[0037] (4) The modified silicon carbide, nano carboxymethyl cellulose sodium hydrogel and flame retardant are mixed evenly at a mass ratio of 1:13:0.25, stirred at 3000 rpm for 7 minutes, and naturally cooled to room temperature to obtain an environmentally friendly lithium battery fire extinguishing agent.

[0038] Example 3:

[0039] A method for preparing an environmentally friendly lithium battery fire extinguishing agent based on nanofiber gel includes the following preparation steps:

[0040] (1) Sodium carboxymethyl cellulose and deionized water were mixed evenly at a mass ratio of 1:20 to obtain an aqueous solution of sodium carboxymethyl cellulose; the aqueous solution of sodium carboxymethyl cellulose was added to a high-pressure homogenizer and homogenized three times at 40 MPa, and then homogenized once at 140 MPa to obtain nano-sodium carboxymethyl cellulose; under a nitrogen atmosphere, nano-sodium carboxymethyl cellulose, N-isopropylacrylamide, N,N-methylenebisacrylamide, and deionized water were mixed at a mass ratio of 1:10:0.1:40. The mixture was homogeneous, and ammonium persulfate (0.4 times the mass of sodium carboxymethyl cellulose nanoparticles) and tetramethylethylenediamine (0.6 times the mass of sodium carboxymethyl cellulose nanoparticles) were added. The mixture was stirred at 300 r / min for 24 h at 4 °C and then allowed to stand at 30 °C for 48 h to obtain a semi-interpenetrating network hydrogel. The semi-interpenetrating network hydrogel and 2 wt% calcium lactate aqueous solution were mixed homogeneously at a mass ratio of 1:0.8 and stirred at 4000 rpm for 12 min at room temperature to obtain sodium carboxymethyl cellulose nanoparticle hydrogel.

[0041] (2) Dodecyltriethoxysilane and deionized water were mixed evenly at a mass ratio of 1:2.2. Silicon carbide with a mass of 0.4 times that of dodecyltriethoxysilane and anhydrous ethanol with a mass of 7 times that of dodecyltriethoxysilane were added and mixed evenly. The mixture was stirred at 80°C and 300 r / min for 4 h. The mixture was then centrifuged at 10000 rpm for 12 min. The precipitate was washed 4 times with anhydrous ethanol and dried under vacuum at 70°C for 6 h to obtain modified silicon carbide.

[0042] (3) Mix 2,4,6-tris(4-aminophenyl)-1,3,5-triazine, 2,5-dihydroxyterephthalaldehyde, and acetonitrile at a mass ratio of 1:0.9:30 until homogeneous, sonicate for 30 min, add glacial acetic acid at 50 times the mass of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine and mix until homogeneous, sonicate for 3 min, let stand at room temperature for 36 h, centrifuge at 10,000 rpm for 12 min, and separate the precipitate with tetrahydrofuran and anhydrous ethanol. The covalent organic framework was prepared by washing four times and vacuum drying at 70℃ for 24 hours. Under a nitrogen atmosphere, the covalent organic framework, triethylamine, potassium carbonate, and tetrahydrofuran were mixed evenly in a mass ratio of 1:0.5:0.6:15. At room temperature, 1.8 times the mass of dimethyl chlorophosphate was added dropwise over 30 minutes. The mixture was stirred at 65℃ and 300 r / min for 12 hours. The mixture was filtered and washed four times with deionized water. The mixture was then vacuum dried at 90℃ for 24 hours to obtain the flame retardant.

[0043] (4) The modified silicon carbide, nano carboxymethyl cellulose sodium hydrogel and flame retardant are mixed evenly at a mass ratio of 1:15:0.3, stirred at 4000 rpm for 8 minutes, and naturally cooled to room temperature to obtain an environmentally friendly lithium battery fire extinguishing agent.

[0044] Comparative Example 1:

[0045] The difference between the preparation method of the environmentally friendly lithium battery fire extinguishing agent based on nanofiber gel in Comparative Example 1 and Example 2 lies in the different step (1). Step (1) is modified as follows: sodium carboxymethyl cellulose and deionized water are mixed evenly at a mass ratio of 1:18 to obtain an aqueous solution of sodium carboxymethyl cellulose; the aqueous solution of sodium carboxymethyl cellulose is added to a high-pressure homogenizer and homogenized twice at 35 MPa, and then homogenized once at 135 MPa to obtain nano-sodium carboxymethyl cellulose; the nano-sodium carboxymethyl cellulose and 2wt% calcium lactate aqueous solution are mixed evenly at a mass ratio of 1:0.7, and stirred at 3000 rpm for 11 min at room temperature to obtain nano-sodium carboxymethyl cellulose hydrogel. The remaining steps are the same as in Example 2.

[0046] Comparative Example 2:

[0047] The preparation method of the environmentally friendly lithium battery fire extinguishing agent based on nanofiber gel in Comparative Example 2 differs from that in Example 2 in step (1). Step (1) is modified as follows: sodium carboxymethyl cellulose and deionized water are mixed evenly at a mass ratio of 1:18 to obtain an aqueous solution of sodium carboxymethyl cellulose; the aqueous solution of sodium carboxymethyl cellulose is added to a high-pressure homogenizer and homogenized twice at 35 MPa, and then homogenized once at 135 MPa to obtain nano-sodium carboxymethyl cellulose; under a nitrogen atmosphere, nano-sodium carboxymethyl cellulose, N-isopropylacrylamide, N,N-methylenebisacrylamide, and deionized water are mixed evenly at a mass ratio of 1:9:0.09:35, and 0.3 times the mass of ammonium persulfate and 0.5 times the mass of tetramethylethylenediamine are added. The mixture is stirred at 3°C ​​and 250 r / min for 22 h, and then allowed to stand at 25°C for 44 h to obtain nano-sodium carboxymethyl cellulose hydrogel. The remaining steps are the same as in Example 2.

[0048] Comparative Example 3:

[0049] The preparation method of the environmentally friendly lithium battery fire extinguishing agent based on nanofiber gel in Comparative Example 3 differs from that in Example 2 in that step (2) is omitted, and step (4) is modified as follows: AEROSIL R812S type silica, nano-carboxymethyl cellulose sodium hydrogel, and flame retardant are mixed evenly at a mass ratio of 1:13:0.25, stirred at 3000 rpm for 7 min, and naturally cooled to room temperature to obtain the environmentally friendly lithium battery fire extinguishing agent. The remaining steps are the same as in Example 2.

[0050] Comparative Example 4:

[0051] The preparation method of the environmentally friendly lithium battery fire extinguishing agent based on nanofiber gel in Comparative Example 4 differs from that in Example 2 in that step (3) is omitted, and step (4) is modified as follows: the modified silicon carbide and nano-carboxymethyl cellulose sodium hydrogel are mixed evenly at a mass ratio of 1:13, stirred at 3000 rpm for 7 min, and naturally cooled to room temperature to obtain the environmentally friendly lithium battery fire extinguishing agent. The remaining steps are the same as in Example 2.

[0052] Test example:

[0053] Fire extinguishing performance test: The specific test method is as follows:

[0054] Experimental setup: A 3.7V ternary polymer soft-pack lithium battery was used as the battery sample and placed in a combustion pan measuring 25cm wide and 35cm long. A resistance wire heater was used to heat the battery until it ignited. The battery combustion and extinguishing process took place within the combustion chamber to minimize the influence of environmental meteorological factors such as wind speed and air temperature on the experimental data. An observation window was located on the front of the combustion chamber, and a side opening was used for spraying the extinguishing agent. The extinguishing agent was stored in a high-pressure powder storage tank under nitrogen pressure at 0.5MPa. After the battery had stabilized during combustion, the powder was sprayed into the ignition source. Temperature data during combustion was collected using a K-type sheathed thermocouple, which was placed in close contact with the surface of the burning sample. Data was recorded using a paperless recorder and transferred to a computer via a USB interface.

[0055] Experimental Procedure: Weigh 100g of environmentally friendly lithium battery fire extinguishing agent and store it in a high-pressure powder storage tank. Pressurize the tank to 0.5MPa using nitrogen. Place a lithium battery sample in the center of a sample tray. Heat the battery sample using a heating plate and record the temperature data using a temperature measuring device. Once the sample is burning stably, begin spraying the fire extinguishing agent. Stop spraying after the open flame is extinguished. Weigh and record the remaining powder after extinguishing the fire. Stop recording when the temperature drops below 100℃. Perform three repeated tests on the environmentally friendly lithium battery fire extinguishing agents obtained from each example and test example, recording the average extinguishing time, the average amount of environmentally friendly lithium battery fire extinguishing agent used, and whether reignition occurred.

[0056] In the preliminary test, the combustion temperature of the battery sample was 630-640℃, and the temperature was around 300℃ when the open flame was extinguished.

[0057] The results are shown in Table 1.

[0058] Table 1

[0059]

[0060]

[0061] A comparison of the experimental data from Examples 1-3 and Comparative Examples 1-4 in Table 1 reveals that the environmentally friendly lithium battery fire extinguishing agent prepared in this invention has excellent fire extinguishing performance.

[0062] By comparison, the fire extinguishing performance of Examples 1-3 is greater than that of Comparative Examples 1-2, indicating that the semi-interpenetrating network hydrogel prepared by reacting nano-sodium carboxymethyl cellulose, N-isopropylacrylamide, and N,N-methylenebisacrylamide, with N,N-methylenebisacrylamide as a crosslinking agent, crosslinks with N-isopropylacrylamide to form a semi-interpenetrating network hydrogel. The hydrogel contains a large amount of water, which can absorb a large amount of heat when evaporating, thereby reducing the temperature of the burning material. At the same time, at high temperatures, the semi-interpenetrating network hydrogel is in a gel state with a certain viscosity, which can adhere to the surface of the burning material, isolating the internal combustible gas from contact with oxygen and reducing the possibility of reignition. The nano-sodium carboxymethyl cellulose hydrogel is prepared by crosslinking the semi-interpenetrating network hydrogel with calcium lactate. The carboxylate ions crosslink with calcium ions to form a three-dimensional network structure hydrogel, which improves the water retention capacity of the hydrogel, thereby enhancing the fire extinguishing performance of the environmentally friendly lithium battery fire extinguishing agent.

[0063] By comparison, the fire extinguishing performance of Examples 1-3 is greater than that of Comparative Example 3, indicating that the modified silicon carbide prepared by reacting dodecyltriethoxysilane and silicon carbide has superhydrophobic properties. When combined with nano-carboxymethyl cellulose sodium hydrogel and flame retardant under stirring conditions, a gel dry water extinguishing agent is prepared, which improves water retention and enhances the fire extinguishing performance of the environmentally friendly lithium battery fire extinguishing agent. At the same time, silicon carbide has good thermal conductivity, which can quickly dissipate the heat generated during combustion, reduce the temperature of the burning material, and reduce the possibility of reignition, thereby enhancing the fire extinguishing performance of the environmentally friendly lithium battery fire extinguishing agent.

[0064] By comparison, the fire extinguishing performance of Examples 1-3 was greater than that of Comparative Example 4, indicating that the amino group on 2,4,6-tris(4-aminophenyl)-1,3,5-triazine reacts with the aldehyde group on 2,5-dihydroxyterephthalaldehyde to form a covalent organic framework. This framework then reacts with dimethyl chlorophosphate to introduce phosphorus into the covalent organic framework. This phosphorus, along with the nitrogen element of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine, synergistically retards the flame, reduces the possibility of reignition, and enhances the fire extinguishing performance of the environmentally friendly lithium battery fire extinguishing agent.

[0065] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing an environmentally friendly lithium battery fire extinguishing agent based on nanofiber gel, characterized in that, The environmentally friendly lithium battery fire extinguishing agent is prepared by mixing and stirring modified silicon carbide, nano-carboxymethyl cellulose sodium hydrogel, and flame retardant. The modified silicon carbide is prepared by reacting silicon carbide with dodecyltriethoxysilane; The nano-carboxymethyl cellulose sodium hydrogel is prepared by reacting nano-carboxymethyl cellulose sodium, N-isopropylacrylamide, and N,N-methylenebisacrylamide to obtain a semi-interpenetrating network hydrogel, which is then crosslinked with calcium lactate. The flame retardant is prepared by reacting 2,4,6-tris(4-aminophenyl)-1,3,5-triazine and 2,5-dihydroxyterephthalaldehyde with a Schiff base reaction, followed by reaction with dimethyl chlorophosphate.

2. The preparation method of an environmentally friendly lithium battery fire extinguishing agent based on nanofiber gel according to claim 1, characterized in that, The preparation steps include the following: (1) Under a nitrogen atmosphere, nano-carboxymethyl cellulose sodium, N-isopropylacrylamide, N,N-methylenebisacrylamide, and deionized water were mixed evenly at a mass ratio of 1:(8-10):(0.08-0.1):(30-40). Ammonium persulfate and tetramethylethylenediamine (0.2-0.4 times the mass of nano-carboxymethyl cellulose sodium) were added. The mixture was stirred at 200-300 r / min at 2-4℃ for 20-24 h and then allowed to stand at 20-30℃ for 40-48 h to obtain a semi-interpenetrating network hydrogel. The semi-interpenetrating network hydrogel and 2wt% calcium lactate aqueous solution were mixed evenly at a mass ratio of 1:(0.6-0.8). The mixture was stirred at 2000-4000 rpm at room temperature for 10-12 min to obtain nano-carboxymethyl cellulose sodium hydrogel. (2) Mix modified silicon carbide, nano carboxymethyl cellulose sodium hydrogel and flame retardant at a mass ratio of 1:(10~15):(0.2~0.3) until uniform, stir at a speed of 2000~4000rpm for 6~8min, and cool naturally to room temperature to obtain an environmentally friendly lithium battery fire extinguishing agent.

3. The method for preparing an environmentally friendly lithium battery fire extinguishing agent based on nanofiber gel according to claim 2, characterized in that, The preparation process of the nano sodium carboxymethyl cellulose in step (1) is as follows: add the sodium carboxymethyl cellulose aqueous solution into a high-pressure homogenizer, homogenize it 1 to 3 times under the condition of 30 to 40 MPa, and then homogenize it once at 130 to 140 MPa to obtain nano sodium carboxymethyl cellulose.

4. The preparation method of an environmentally friendly lithium battery fire extinguishing agent based on nanofiber gel according to claim 3, characterized in that, The sodium carboxymethyl cellulose aqueous solution is prepared by uniformly mixing sodium carboxymethyl cellulose and deionized water at a mass ratio of 1:(15-20).

5. The preparation method of an environmentally friendly lithium battery fire extinguishing agent based on nanofiber gel according to claim 3, characterized in that, The nozzle model of the high-pressure homogenizer is D8.

6. The method for preparing an environmentally friendly lithium battery fire extinguishing agent based on nanofiber gel according to claim 2, characterized in that, The preparation process of modified silicon carbide in step (2) is as follows: dodecyltriethoxysilane and deionized water are mixed evenly at a mass ratio of 1:(1.8-2.2), silicon carbide with a mass of 0.2-0.4 times that of dodecyltriethoxysilane and anhydrous ethanol with a mass of 5-7 times that of dodecyltriethoxysilane are added and mixed evenly. The mixture is stirred at 70-80℃ and 200-300r / min for 3-4h, centrifuged at 8000-10000rpm for 10-12min, the precipitate is washed 2-4 times with anhydrous ethanol, and vacuum dried at 60-70℃ for 4-6h to obtain modified silicon carbide.

7. The method for preparing an environmentally friendly lithium battery fire extinguishing agent based on nanofiber gel according to claim 2, characterized in that, The preparation process of the flame retardant in step (2) is as follows: Under a nitrogen atmosphere, covalent organic framework, triethylamine, potassium carbonate, and tetrahydrofuran are mixed evenly in a mass ratio of 1:(0.4-0.5):(0.5-0.6):(10-15). At room temperature, 1.6-1.8 times the mass of covalent organic framework dimethyl chlorophosphate is added dropwise at a uniform rate over 30 minutes. The mixture is stirred at 55-65°C and 200-300 r / min for 10-12 hours. The mixture is filtered and washed 2-4 times with deionized water. It is then vacuum dried at 80-90°C for 20-24 hours to obtain the flame retardant.

8. The method for preparing an environmentally friendly lithium battery fire extinguishing agent based on nanofiber gel according to claim 7, characterized in that, The preparation process of the covalent organic framework is as follows: 2,4,6-tris(4-aminophenyl)-1,3,5-triazine, 2,5-dihydroxyterephthalaldehyde, and acetonitrile are mixed evenly at a mass ratio of 1:(0.8-0.9):(20-30), and sonicated for 30 min. Then, 40-50 times the mass of glacial acetic acid of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine is added and mixed evenly. The mixture is sonicated for 1-3 min and allowed to stand at room temperature for 24-36 h. The mixture is then centrifuged at 8000-10000 rpm for 10-12 min. The resulting precipitate is washed 2-4 times each with tetrahydrofuran and anhydrous ethanol, and then vacuum dried at 60-70℃ for 22-24 h to obtain the covalent organic framework.

9. The method for preparing an environmentally friendly lithium battery fire extinguishing agent based on nanofiber gel according to claim 4, characterized in that, The viscosity of the sodium carboxymethyl cellulose is 800–1200 mPa·s.

10. The method for preparing an environmentally friendly lithium battery fire extinguishing agent based on nanofiber gel according to claim 6, characterized in that, The silicon carbide has a particle size of 30–50 nm.

Images