Fire extinguishing agent for battery fire prevention and control and preparation method thereof

Abstract

The invention discloses a fire extinguishing agent for battery fire prevention and control and a preparation method thereof, and relates to the technical field of fire extinguishing materials. When preparing the fire extinguishing agent for battery fire prevention and control, the present invention reacts lanthanum nitrate hexahydrate with 1,3,5-tribenzoic acid to obtain a lanthanum organic metal framework; adopts a solution crystallization technique to load ammonium dihydrogen phosphate onto the lanthanum organic metal framework to obtain composite flame retardant particles; cellulose is reacted with sodium hydroxide and sodium acrylate in sequence to obtain modified cellulose; the modified cellulose is mixed with composite flame retardant particles and expanded graphite, and cross-linked with N,N'-methylenebisacrylamide to obtain a thermosensitive hydrogel; the thermosensitive hydrogel is mixed with sodium carbonate and glacial acetic acid, and ground into microparticles after drying to obtain a fire extinguishing agent for battery fire prevention and control. The fire extinguishing agent for battery fire prevention and control prepared by the present invention has excellent fire extinguishing performance.

Description

Technical Field

[0001] The present invention relates to the technical field of fire extinguishing materials, and in particular to a fire extinguishing agent for battery fire prevention and control and a preparation method thereof. Background Art

[0002] With the rapid development of the new energy industry, lithium-ion batteries, as the most competitive intermediate energy storage medium in the market, have been widely used in energy storage systems and electric vehicles due to their long service life, high energy density, low self-discharge rate, no memory effect and superior environmental friendliness. However, lithium battery fires have occurred from time to time in recent years, and the safety issues of lithium batteries have attracted widespread attention from researchers.

[0003] Lithium battery thermal runaway usually occurs under adverse conditions such as overcharging, overheating or short circuit. Without subsequent protective measures, it is very easy to develop into a violent combustion or even explosion accident, causing great losses to people's lives and property. Therefore, it is necessary to propose a fire extinguishing agent for battery fire prevention and control and its preparation method, so as to extinguish the fire in time when a battery fire accident occurs, prevent the fire from spreading, and protect people's lives and property. Summary of the invention

[0004] The purpose of the present invention is to provide a fire extinguishing agent for battery fire prevention and control and a preparation method thereof, so as to solve the problems existing in the prior art.

[0005] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0006] A fire extinguishing agent for battery fire prevention and control, wherein the fire extinguishing agent for battery fire prevention and control is prepared by loading ammonium dihydrogen phosphate onto a lanthanum organic metal framework using a dissolution crystallization technology to obtain composite flame retardant particles; mixing modified cellulose with the composite flame retardant particles and expanded graphite, and cross-linking with N,N'-methylenebisacrylamide to obtain a temperature-sensitive hydrogel; mixing the temperature-sensitive hydrogel with sodium carbonate and glacial acetic acid, and grinding the mixture into microparticles after drying;

[0007] The lanthanum organic metal framework is prepared by reacting lanthanum nitrate hexahydrate with 1,3,5-tribenzoic acid;

[0008] The modified cellulose is prepared by reacting cellulose with sodium hydroxide and sodium acrylate in sequence.

[0009] A method for preparing a fire extinguishing agent for battery fire prevention and control, comprising the following preparation steps:

[0010] (1) At room temperature, ammonium dihydrogen phosphate and deionized water are mixed uniformly in a mass ratio of 1:(2.3-2.5) to prepare a saturated ammonium dihydrogen phosphate solution, 0.3-0.4 times the mass of the ammonium dihydrogen phosphate lanthanum organic metal framework is added, the mixture is mixed uniformly, ultrasonically dispersed for 20-30 minutes, anhydrous ethanol is added in an amount of 0.5-0.7 times the mass of the saturated ammonium dihydrogen phosphate solution, stirred at 10-30° C. and 300-500 r / min for 2-3 hours, allowed to stand for 1-2 hours, filtered, and dried at 50-60° C. under vacuum conditions for 5-6 hours to obtain composite flame retardant particles;

[0011] (2) Modified cellulose, N,N'-methylenebisacrylamide, composite flame retardant particles, expanded graphite, and deionized water are mixed uniformly in a mass ratio of 1:(0.1-0.2):(0.05-0.07):(0.04-0.06):(8-10), and under nitrogen protection, a potassium persulfate aqueous solution with a mass fraction of 8-10% and a mass fraction of 2-3 times the mass of the modified cellulose is added dropwise within 10 minutes, the temperature is raised to 50-60°C, and stirring is continued for 1-2 hours to obtain a thermosensitive hydrogel; sodium carbonate with a mass fraction of 0.03-0.05 times the mass of the thermosensitive hydrogel and glacial acetic acid with a mass fraction of 0.03-0.05 times the mass of the thermosensitive hydrogel are added to the thermosensitive hydrogel, and stirring is continued for 2-4 minutes. Under vacuum conditions, it is dried at 60-70°C for 7-9 hours, crushed with a crusher, and then ground into powder with a ball mill, and passed through a 400-500 mesh sieve to obtain a fire extinguishing agent for battery fire prevention and control.

[0012] As an optimization, the lanthanum organic metal framework in step (1) is prepared by uniformly mixing a lanthanum nitrate dispersion with a 1,3,5-tribenzoic acid solution, stirring at 20 to 30° C. and 300 to 500 r / min for 3 to 4 hours, filtering, washing with anhydrous ethanol and deionized water for 3 to 5 times respectively, and drying at 70 to 80° C. under vacuum conditions for 6 to 8 hours to obtain a lanthanum organic metal framework.

[0013] As an optimization, the lanthanum nitrate dispersion is prepared by uniformly mixing lanthanum nitrate hexahydrate and deionized water in a mass ratio of 1:(40-50), and ultrasonically dispersing for 1-2 hours.

[0014] As an optimization, the 1,3,5-tribenzoic acid solution is prepared by uniformly mixing 1,3,5-tribenzoic acid, anhydrous ethanol and deionized water in an equal molar amount of lanthanum nitrate hexahydrate at a mass ratio of 1:(20-30):(20-30).

[0015] As an optimization, the modified cellulose in step (2) is prepared by uniformly mixing alkaline cellulose, potassium persulfate and deionized water in a mass ratio of 1:(0.03-0.05):(40-50), stirring at 35-45°C and 300-500 r / min for 8-10 min under nitrogen protection, adding sodium acrylate in an amount 2-3 times the mass of the alkaline cellulose, heating to 50-60°C, continuing to stir for 1-2 h, filtering, and drying at 50-60°C for 5-6 h under vacuum conditions.

[0016] As an optimization, the alkaline cellulose is prepared by uniformly mixing cellulose and a sodium hydroxide aqueous solution with a mass fraction of 14 to 16% in a mass ratio of 1:(8 to 10), stirring at 50 to 60° C. and 300 to 500 r / min for 1 to 2 hours, cooling to room temperature, filtering, washing with deionized water for 3 to 5 times, and drying at 50 to 60° C. for 6 to 7 hours under vacuum conditions.

[0017] As an optimization, the molecular weight of the cellulose is 80,000 to 100,000.

[0018] Compared with the prior art, the beneficial effects achieved by the present invention are:

[0019] When preparing a fire extinguishing agent for battery fire prevention and control, the present invention comprises the following steps: reacting lanthanum nitrate hexahydrate with 1,3,5-tribenzoic acid to obtain a lanthanum organic metal framework; adopting a dissolution crystallization technology to load ammonium dihydrogen phosphate onto the lanthanum organic metal framework to obtain composite flame retardant particles; reacting cellulose with sodium hydroxide and sodium acrylate in sequence to obtain modified cellulose; mixing the modified cellulose with the composite flame retardant particles and expanded graphite, and cross-linking with N,N'-methylenebisacrylamide to obtain a temperature-sensitive hydrogel; and mixing the temperature-sensitive hydrogel with sodium carbonate and glacial acetic acid, drying, and grinding the mixture into microparticles to obtain the fire extinguishing agent for battery fire prevention and control.

[0020] Firstly, lanthanum nitrate hexahydrate is reacted with 1,3,5-tribenzoic acid to obtain a lanthanum organometallic framework. Using the dissolution crystallization technology, ammonium dihydrogen phosphate is loaded onto the lanthanum organometallic framework to obtain composite flame retardant particles. The lanthanum oxide produced by the lanthanum organometallic framework during combustion can catalyze carbonization and capture free radicals, promote the formation of a surface carbon layer and inhibit smoke release. Ammonium dihydrogen phosphate is the main component of ABC dry powder fire extinguishing agent, which can interrupt the flame combustion chain reaction and react on the surface of the burning material after contact with the flame to form polyphosphates. According to its usage, a glass layer of a certain thickness is formed, which carbonizes the surface of the burning material, forms a fireproof layer, slows down the combustion process, and prevents the solid from further spreading at high temperature. Moreover, the ammonia released by the decomposition of ammonium dihydrogen phosphate is a non-flammable gas, which can dilute the oxygen in the air, giving the fire extinguishing agent for battery fire prevention and control excellent fire extinguishing performance.

[0021] Secondly, cellulose is reacted with sodium hydroxide and sodium acrylate in sequence to obtain modified cellulose; the modified cellulose is mixed with composite flame retardant particles and expanded graphite, and cross-linked with N,N'-methylenebisacrylamide to obtain a thermosensitive hydrogel; the thermosensitive hydrogel is prepared with cellulose as a raw material, the cellulose is alkalized and reacted with sodium acrylate, a hydrophilic group carboxyl group is grafted on the cellulose to obtain a modified cellulose, N,N'-methylenebisacrylamide is used as a cross-linking agent to prepare the thermosensitive hydrogel, and a hydrophilic group amide group is introduced; the thermosensitive hydrogel contains a large amount of water, and water has a high latent heat of evaporation. During the fire extinguishing process, part of the water in the thermosensitive hydrogel evaporates and absorbs Heat can quickly reduce the temperature of the fire scene. At the same time, the evaporated water vapor also dilutes the oxygen concentration around the burning object. Since the hydrogel is in a gel state at high temperature and has a high viscosity, it will form a covering film with a certain thickness on the solid surface when extinguishing a solid fire, thereby blocking the contact between the combustible and oxygen, playing an oxygen-isolating and blocking role. The hydrogel covering the solid surface will further evaporate and take away the heat. When expanded graphite is added to the thermosensitive hydrogel, the volume of the expanded graphite can instantly expand 150 to 300 times when it encounters high temperature. As the temperature rises, all the water in the thermosensitive hydrogel evaporates, and the expanded graphite expands rapidly, wrapping and sealing the high-temperature fire source to prevent re-ignition.

[0022] Finally, the thermosensitive hydrogel is mixed with sodium carbonate and glacial acetic acid, dried and ground into microparticles to produce a fire extinguishing agent for battery fire prevention and control; sodium carbonate and glacial acetic acid are added to the thermosensitive hydrogel as foaming agents, and react at high temperature to generate carbon dioxide. While carbon dioxide dilutes the oxygen concentration, pores are formed in the gel. The porous structure can respond more quickly to temperature changes, resulting in a rapid loss of water content in the thermosensitive hydrogel at high temperature, which has the effect of rapid cooling. DETAILED DESCRIPTION

[0023] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0024] Example 1

[0025] A method for preparing a fire extinguishing agent for battery fire prevention and control, the method for preparing a fire extinguishing agent for battery fire prevention and control comprising the following preparation steps:

[0026] (1) Lanthanum nitrate hexahydrate and deionized water were mixed at a mass ratio of 1:40, and ultrasonically dispersed for 1 hour to prepare a lanthanum nitrate dispersion; 1,3,5-tribenzoic acid, anhydrous ethanol, and deionized water in an equal molar amount of lanthanum nitrate hexahydrate were mixed at a mass ratio of 1:20:20 to prepare a 1,3,5-tribenzoic acid solution; the lanthanum nitrate dispersion and the 1,3,5-tribenzoic acid solution were mixed evenly, stirred at 20°C and 300 r / min for 4 hours, filtered, washed with anhydrous ethanol and deionized water for 3 times each, and dried in a vacuum oven. Under vacuum conditions, the mixture was dried at 70°C for 8 hours to obtain a lanthanum organic metal framework; at room temperature, ammonium dihydrogen phosphate and deionized water were mixed evenly at a mass ratio of 1:2.3 to prepare a saturated ammonium dihydrogen phosphate solution, 0.3 times the mass of the ammonium dihydrogen phosphate lanthanum organic metal framework was added, the mixture was mixed evenly, ultrasonically dispersed for 20 minutes, anhydrous ethanol was added at 0.5 times the mass of the saturated ammonium dihydrogen phosphate solution, the mixture was stirred at 10°C and 300 r / min for 3 hours, the mixture was allowed to stand for 1 hour, filtered, and dried at 50°C for 6 hours under vacuum conditions to obtain composite flame retardant particles;

[0027] (2) Cellulose and a 14% sodium hydroxide aqueous solution were mixed in a mass ratio of 1:8, stirred at 50°C and 300 r / min for 2 h, cooled to room temperature, filtered, washed with deionized water for 3 times, and dried at 50°C for 7 h under vacuum to obtain alkaline cellulose; alkaline cellulose, potassium persulfate, and deionized water were mixed in a mass ratio of 1:0.03:40, stirred at 35°C and 300 r / min for 10 min under nitrogen protection, sodium acrylate twice the mass of the alkaline cellulose was added, the temperature was raised to 50°C, the reaction was continued with stirring for 2 h, filtered, and dried at 50°C for 6 h under vacuum to obtain modified cellulose; modified cellulose, N,N '-Methylenebisacrylamide, composite flame retardant particles, expanded graphite, and deionized water are mixed in a mass ratio of 1:0.1:0.05:0.04:8. Under nitrogen protection, an 8% potassium persulfate aqueous solution with a mass fraction of twice the mass of modified cellulose is added dropwise within 10 minutes, the temperature is raised to 50°C, and stirring is continued for 2 hours to obtain a thermosensitive hydrogel; sodium carbonate with a mass fraction of 0.03 times the mass of the thermosensitive hydrogel and glacial acetic acid with a mass fraction of 0.03 times the mass of the thermosensitive hydrogel are added to the thermosensitive hydrogel, and stirring is continued for 4 minutes. Under vacuum conditions, it is dried at 60°C for 9 hours, crushed with a crusher, and then ground into powder with a ball mill, and passed through a 400-mesh sieve to obtain a fire extinguishing agent for battery fire prevention and control.

[0028] Example 2

[0029] A method for preparing a fire extinguishing agent for battery fire prevention and control, the method for preparing a fire extinguishing agent for battery fire prevention and control comprising the following preparation steps:

[0030] (1) Lanthanum nitrate hexahydrate and deionized water were mixed at a mass ratio of 1:45, and ultrasonically dispersed for 1.5 hours to prepare a lanthanum nitrate dispersion; 1,3,5-tribenzoic acid, anhydrous ethanol, and deionized water in an equal molar amount of lanthanum nitrate hexahydrate were mixed at a mass ratio of 1:25:25 to prepare a 1,3,5-tribenzoic acid solution; the lanthanum nitrate dispersion and the 1,3,5-tribenzoic acid solution were mixed evenly, stirred at 25°C and 400 r / min for 3.5 hours, filtered, washed with anhydrous ethanol and deionized water 4 times each, and placed in a vacuum condition. Under the condition of drying at 75℃ for 7h, a lanthanum organic metal framework was obtained; at room temperature, ammonium dihydrogen phosphate and deionized water were mixed evenly at a mass ratio of 1:2.4 to prepare a saturated ammonium dihydrogen phosphate solution, 0.35 times the mass of the ammonium dihydrogen phosphate lanthanum organic metal framework was added, mixed evenly, ultrasonically dispersed for 25min, anhydrous ethanol was added at 0.6 times the mass of the saturated ammonium dihydrogen phosphate solution, stirred at 20℃, 400r / min for 2.5h, allowed to stand for 1.5h, filtered, and dried at 55℃ for 5.5h under vacuum conditions to obtain composite flame retardant particles;

[0031] (2) Cellulose and a 15% sodium hydroxide aqueous solution were mixed in a mass ratio of 1:9, stirred at 55°C and 400 r / min for 1.5 h, cooled to room temperature, filtered, washed with deionized water 4 times, and dried at 55°C for 6.5 h under vacuum conditions to obtain alkaline cellulose; alkaline cellulose, potassium persulfate, and deionized water were mixed in a mass ratio of 1:0.04:45, stirred at 40°C and 400 r / min for 9 min under nitrogen protection, sodium acrylate 2.5 times the mass of alkaline cellulose was added, the temperature was raised to 55°C, the reaction was continued with stirring for 1.5 h, filtered, and dried at 55°C for 5.5 h under vacuum conditions to obtain modified cellulose; modified cellulose, N N'-methylenebisacrylamide, composite flame retardant particles, expanded graphite, and deionized water were mixed evenly in a mass ratio of 1:0.15:0.06:0.05:9. Under nitrogen protection, a 9% potassium persulfate aqueous solution with a mass fraction of 2.5 times the mass of modified cellulose was added dropwise within 10 minutes, the temperature was raised to 55°C, and stirring was continued for 1.5 hours to obtain a thermosensitive hydrogel; sodium carbonate with a mass fraction of 0.04 times the mass of the thermosensitive hydrogel and glacial acetic acid with a mass fraction of 0.04 times the mass of the thermosensitive hydrogel were added to the thermosensitive hydrogel, and stirring was continued for 3 minutes. Under vacuum conditions, it was dried at 65°C for 8 hours, crushed with a crusher, and then ground into powder with a ball mill, and passed through a 450-mesh sieve to obtain a fire extinguishing agent for battery fire prevention and control.

[0032] Example 3

[0033] A method for preparing a fire extinguishing agent for battery fire prevention and control, the method for preparing a fire extinguishing agent for battery fire prevention and control comprising the following preparation steps:

[0034] (1) Lanthanum nitrate hexahydrate and deionized water were mixed at a mass ratio of 1:50, and ultrasonically dispersed for 2 hours to prepare a lanthanum nitrate dispersion; 1,3,5-tribenzoic acid, anhydrous ethanol, and deionized water in an equal molar amount of lanthanum nitrate hexahydrate were mixed at a mass ratio of 1:30:30 to prepare a 1,3,5-tribenzoic acid solution; the lanthanum nitrate dispersion and the 1,3,5-tribenzoic acid solution were mixed evenly, stirred at 30°C and 500 r / min for 3 hours, filtered, washed with anhydrous ethanol and deionized water for 5 times each, and dried in a vacuum oven. Under vacuum conditions, the mixture was dried at 80°C for 6 hours to obtain a lanthanum organic metal framework; at room temperature, ammonium dihydrogen phosphate and deionized water were mixed at a mass ratio of 1:2.5 to prepare a saturated ammonium dihydrogen phosphate solution, 0.4 times the mass of the ammonium dihydrogen phosphate lanthanum organic metal framework was added, the mixture was mixed evenly, ultrasonically dispersed for 30 minutes, anhydrous ethanol was added at 0.7 times the mass of the saturated ammonium dihydrogen phosphate solution, stirred at 30°C and 500 r / min for 2 hours, allowed to stand for 2 hours, filtered, and dried at 60°C for 5 hours under vacuum conditions to obtain composite flame retardant particles;

[0035] (2) Cellulose and a 16% sodium hydroxide aqueous solution were mixed in a mass ratio of 1:10, stirred at 60°C and 500 r / min for 1 hour, cooled to room temperature, filtered, washed with deionized water for 5 times, and dried at 60°C for 6 hours under vacuum conditions to obtain alkaline cellulose; alkaline cellulose, potassium persulfate, and deionized water were mixed in a mass ratio of 1:0.05:50, stirred at 45°C and 500 r / min for 8 minutes under nitrogen protection, sodium acrylate 3 times the mass of alkaline cellulose was added, the temperature was raised to 60°C, the reaction was continued with stirring for 1 hour, filtered, and dried at 60°C for 5 hours under vacuum conditions to obtain modified cellulose; modified cellulose, N,N' -Methylenebisacrylamide, composite flame retardant particles, expanded graphite, and deionized water are mixed in a mass ratio of 1:0.2:0.07:0.06:10. Under nitrogen protection, a 10% potassium persulfate aqueous solution with a mass fraction of 3 times the mass of modified cellulose is added dropwise within 10 minutes, the temperature is raised to 60°C, and stirring is continued for 1 hour to obtain a thermosensitive hydrogel; sodium carbonate with a mass of 0.05 times the mass of the thermosensitive hydrogel and glacial acetic acid with a mass of 0.05 times the mass of the thermosensitive hydrogel are added to the thermosensitive hydrogel, and stirring is continued for 2 minutes. Under vacuum conditions, it is dried at 70°C for 7 hours, crushed with a crusher, and then ground into powder with a ball mill, and passed through a 500-mesh sieve to obtain a fire extinguishing agent for battery fire prevention and control.

[0036] Comparative Example 1

[0037] The preparation method of the fire extinguishing agent for battery fire prevention and control of Comparative Example 1 is different from that of Example 2 in that step (1) is not performed, and step (2) is modified as follows: cellulose and a sodium hydroxide aqueous solution with a mass fraction of 15% are mixed uniformly in a mass ratio of 1:9, stirred at 55°C and 400r / min for 1.5h, cooled to room temperature, filtered, washed with deionized water 4 times, and dried at 55°C for 6.5h under vacuum conditions to obtain alkaline cellulose; alkaline cellulose, potassium persulfate, and deionized water are mixed uniformly in a mass ratio of 1:0.04:45, stirred at 40°C and 400r / min for 9min under nitrogen protection, sodium acrylate 2.5 times the mass of alkaline cellulose is added, the temperature is raised to 55°C, the reaction is continued with stirring for 1.5h, filtered, and dried at 55°C under vacuum conditions. ℃ and dried for 5.5h to obtain modified cellulose; modified cellulose, N, N'-methylenebisacrylamide, ammonium dihydrogen phosphate, expanded graphite, and deionized water were mixed uniformly in a mass ratio of 1:0.15:0.06:0.05:9, and a 9% potassium persulfate aqueous solution of 2.5 times the mass of modified cellulose was added dropwise within 10min under nitrogen protection, and the temperature was raised to 55℃, and stirring was continued for 1.5h to obtain a thermosensitive hydrogel; sodium carbonate of 0.04 times the mass of the thermosensitive hydrogel and glacial acetic acid of 0.04 times the mass of the thermosensitive hydrogel were added to the thermosensitive hydrogel, and stirring was continued for 3min, and dried at 65℃ for 8h under vacuum conditions, crushed with a crusher, and then ground into powder with a ball mill, and passed through a 450-mesh sieve to obtain a fire extinguishing agent for battery fire prevention and control. The remaining steps are the same as in Example 2.

[0038] Comparative Example 2

[0039] The preparation method of the fire extinguishing agent for battery fire prevention and control in Comparative Example 2 is different from that in Example 2 in that step (1) is different, and step (1) is modified as follows: lanthanum nitrate hexahydrate and deionized water are mixed evenly at a mass ratio of 1:45, and ultrasonically dispersed for 1.5 hours to obtain a lanthanum nitrate dispersion; 1,3,5-tribenzoic acid, anhydrous ethanol, and deionized water in an equal molar amount of lanthanum nitrate hexahydrate are mixed evenly at a mass ratio of 1:25:25 to prepare a 1,3,5-tribenzoic acid solution; the lanthanum nitrate dispersion and the 1,3,5-tribenzoic acid solution are mixed evenly, stirred at 25°C and 400r / min for 3.5 hours, filtered, washed 4 times with anhydrous ethanol and deionized water respectively, and dried at 75°C for 7 hours under vacuum conditions to obtain composite flame retardant particles. The remaining steps are the same as in Example 2.

[0040] Comparative Example 3

[0041] The preparation method of the fire extinguishing agent for battery fire prevention and control in Comparative Example 3 is different from that in Example 2 only in step (2). Step (2) is modified as follows: cellulose and a sodium hydroxide aqueous solution with a mass fraction of 15% are mixed in a mass ratio of 1:9, stirred at 55°C and 400r / min for 1.5h, cooled to room temperature, filtered, washed with deionized water 4 times, and dried at 55°C for 6.5h under vacuum conditions to obtain alkaline cellulose; alkaline cellulose, potassium persulfate, and deionized water are mixed in a mass ratio of 1:0.04:45, stirred at 40°C and 400r / min for 9min under nitrogen protection, sodium acrylate 2.5 times the mass of alkaline cellulose is added, and the temperature is raised to 55°C. , continue to stir the reaction for 1.5h, filter, and dry at 55°C for 5.5h under vacuum conditions to obtain modified cellulose; the modified cellulose, N,N'-methylenebisacrylamide, composite flame retardant particles, expanded graphite, and deionized water are mixed uniformly at a mass ratio of 1:0.15:0.06:0.05:9, and under nitrogen protection, a 9% potassium persulfate aqueous solution of 2.5 times the mass of the modified cellulose is added dropwise within 10min, the temperature is raised to 55°C, and stirring is continued for 1.5h to obtain a thermosensitive hydrogel; the thermosensitive hydrogel is dried at 65°C for 8h under vacuum conditions, crushed with a crusher, and then ground into powder with a ball mill, and passed through a 450-mesh sieve to obtain a fire extinguishing agent for battery fire prevention and control. The remaining steps are the same as in Example 2.

[0042] Comparative Example 4

[0043] The preparation method of the fire extinguishing agent for battery fire prevention and control of Comparative Example 4 is different from that of Example 2 only in step (2). Step (2) is modified as follows: cellulose and a sodium hydroxide aqueous solution with a mass fraction of 15% are mixed in a mass ratio of 1:9, stirred at 55°C and 400r / min for 1.5h, cooled to room temperature, filtered, washed with deionized water 4 times, and dried at 55°C for 6.5h under vacuum conditions to obtain alkaline cellulose; alkaline cellulose, potassium persulfate, and deionized water are mixed in a mass ratio of 1:0.04:45, stirred at 40°C and 400r / min for 9min under nitrogen protection, sodium acrylate 2.5 times the mass of alkaline cellulose is added, the temperature is raised to 55°C, the reaction is continued with stirring for 1.5h, filtered, and dried under vacuum conditions. Conditions, 55 ° C drying for 5.5h to obtain modified cellulose; modified cellulose, N, N'-methylenebisacrylamide, composite flame retardant particles, deionized water are mixed in a mass ratio of 1: 0.15: 0.06: 9, and under nitrogen protection, a 9% potassium persulfate aqueous solution of 2.5 times the mass of modified cellulose is added dropwise within 10min, the temperature is raised to 55 ° C, and stirring is continued for 1.5h to obtain a thermosensitive hydrogel; sodium carbonate 0.04 times the mass of the thermosensitive hydrogel and glacial acetic acid 0.04 times the mass of the thermosensitive hydrogel are added to the thermosensitive hydrogel, and stirring is continued for 3min. Under vacuum conditions, it is dried at 65 ° C for 8h, crushed with a crusher, and then ground into powder with a ball mill, and passed through a 450-mesh sieve to obtain a fire extinguishing agent for battery fire prevention and control. The remaining steps are the same as in Example 2.

[0044] Comparative Example 5

[0045] The preparation method of the fire extinguishing agent for battery fire prevention and control in Comparative Example 5 is different from that in Example 2 in that step (2) is not performed, and step (1) is modified as follows: lanthanum nitrate hexahydrate and deionized water are mixed uniformly in a mass ratio of 1:45, and ultrasonically dispersed for 1.5 hours to obtain a lanthanum nitrate dispersion; 1,3,5-tribenzoic acid, anhydrous ethanol, and deionized water in an equal molar amount of lanthanum nitrate hexahydrate are mixed uniformly in a mass ratio of 1:25:25 to prepare a 1,3,5-tribenzoic acid solution; the lanthanum nitrate dispersion and the 1,3,5-tribenzoic acid solution are mixed uniformly, stirred at 25 ° C, 400 r / min for 3.5 hours, and filtered. , washed with anhydrous ethanol and deionized water for 4 times respectively, dried at 75°C for 7 hours under vacuum conditions to obtain a lanthanum organic metal framework; at room temperature, ammonium dihydrogen phosphate and deionized water were mixed evenly in a mass ratio of 1:2.4 to prepare a saturated solution of ammonium dihydrogen phosphate, 0.35 times the mass of ammonium dihydrogen phosphate lanthanum organic metal framework was added, mixed evenly, ultrasonically dispersed for 25 minutes, 0.6 times the mass of the saturated solution of ammonium dihydrogen phosphate was added with anhydrous ethanol, stirred at 20°C and 400r / min for 2.5 hours, allowed to stand for 1.5 hours, filtered, and dried at 55°C for 5.5 hours under vacuum conditions to obtain a fire extinguishing agent for battery fire prevention and control.

[0046] Test Case

[0047] Fire extinguishing performance test

[0048] Test method: dilute the embodiment and comparative example with water to a concentration of 3-4%, and put them into a fire extinguisher bottle. The nozzle of the fire extinguisher bottle is a DN15 water mist nozzle. When using, first put the prepared fire extinguishing agent into the bottle, and then fill the bottle with air to maintain the pressure in the bottle at 1.2Mpa; use 18650 lithium battery to conduct thermal runaway test. When the lithium battery is heated to the point of explosion, turn off the heating rod, and the fire extinguisher will hold the fire extinguisher bottle and spray freely until the flame is extinguished, and record the fire extinguishing time. The results are shown in Table 1.

[0049] Table 1

[0050] Fire extinguishing time(s) Fire extinguishing time(s) Example 1 2.83 Comparative Example 1 8.36 Example 2 2.75 Comparative Example 2 9.14 Example 3 3.06 Comparative Example 3 7.53 Comparative Example 4 6.33 Comparative Example 5 12.58

[0051] From the comparison of the experimental data of Examples 1 to 3 and Comparative Examples 1 to 5 in Table 1, it can be found that the fire extinguishing agent for battery fire prevention and control prepared by the present invention has good fire extinguishing performance.

[0052] By comparison, the fire extinguishing time of Examples 1 to 3 is shorter than that of Comparative Example 1, indicating that the lanthanum organic metal framework is prepared by reacting lanthanum nitrate hexahydrate with 1,3,5-tribenzoic acid; ammonium dihydrogen phosphate is loaded onto the lanthanum organic metal framework by dissolution crystallization technology to prepare composite flame retardant particles; lanthanum oxide produced by the lanthanum organic metal framework during combustion can catalyze carbonization and capture free radicals, promote the formation of a surface carbon layer and inhibit smoke release, and endow the fire extinguishing agent for battery fire prevention and control with excellent fire extinguishing performance.

[0053] By comparison, the fire extinguishing time of Examples 1 to 3 is shorter than that of Comparative Example 2, indicating that the lanthanum organic metal framework is prepared by reacting lanthanum nitrate hexahydrate with 1,3,5-tribenzoic acid; ammonium dihydrogen phosphate is loaded onto the lanthanum organic metal framework by dissolution crystallization technology to prepare composite flame retardant particles; ammonium dihydrogen phosphate is the main component of ABC dry powder fire extinguishing agent, which can interrupt the flame combustion chain reaction, and can also react on the surface of the burning object after contact with the flame to form polyphosphate, and form a glass layer of a certain thickness according to its usage amount, carbonize the surface of the burning object, form a fireproof layer, slow down the combustion process, and prevent the solid from further spreading at high temperature; and the ammonia released by the decomposition of ammonium dihydrogen phosphate is a non-flammable gas, which can dilute the oxygen in the air, giving the fire extinguishing agent for battery fire prevention and control excellent fire extinguishing performance.

[0054] By comparison, the fire extinguishing time of Examples 1 to 3 is shorter than that of Comparative Examples 3 to 5, indicating that cellulose is reacted with sodium hydroxide and sodium acrylate in sequence to obtain modified cellulose; the modified cellulose is mixed with composite flame retardant particles and expanded graphite, and cross-linked with N,N'-methylenebisacrylamide to obtain a thermosensitive hydrogel; the thermosensitive hydrogel is prepared using cellulose as a raw material, the cellulose is alkalized and then reacted with sodium acrylate, a hydrophilic group carboxyl group is grafted onto the cellulose to obtain the modified cellulose, the thermosensitive hydrogel is prepared using N,N'-methylenebisacrylamide as a cross-linking agent, and a hydrophilic group amide group is introduced; the thermosensitive hydrogel contains a large amount of water, and water has a high latent heat of evaporation. During the fire extinguishing process, part of the water in the thermosensitive hydrogel evaporates and absorbs heat, rapidly reducing the temperature of the fire scene. At the same time, the evaporated water vapor also dilutes the oxygen concentration around the burning object; since the hydrogel is in a gel state at high temperature and has a high viscosity, it will form on the solid surface when extinguishing a solid fire. The thermosensitive hydrogel is formed into a covering film with a certain thickness, thereby blocking the contact between the combustible and oxygen, and playing the role of oxygen isolation and blocking; the hydrogel covering the solid surface will further evaporate and take away the heat; the expanded graphite is added to the thermosensitive hydrogel, and the volume of the expanded graphite can instantly expand 150 to 300 times when it encounters high temperature. As the temperature rises, after all the water in the thermosensitive hydrogel evaporates, the expanded graphite expands rapidly, wraps and seals the high-temperature fire source to prevent re-ignition; the thermosensitive hydrogel is mixed with sodium carbonate and glacial acetic acid, and then ground into microparticles after drying to obtain a fire extinguishing agent for battery fire prevention and control; sodium carbonate and glacial acetic acid are added to the thermosensitive hydrogel as foaming agents, and react at high temperature to generate carbon dioxide. While carbon dioxide dilutes the oxygen concentration, pores are formed in the gel. The porous structure can respond more quickly to temperature changes, resulting in a rapid loss of water content in the thermosensitive hydrogel at high temperature, which plays a role of rapid cooling and further improving the fire extinguishing performance of the fire extinguishing agent for battery fire prevention and control.

[0055] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method 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 in the scope of protection of the present invention.

Claims

1. A fire extinguishing agent for battery fire prevention and control, characterized in that: The fire extinguishing agent for battery fire prevention and control is prepared by loading ammonium dihydrogen phosphate onto a lanthanum organic metal framework using a dissolution crystallization technology to prepare composite flame retardant particles; mixing modified cellulose with the composite flame retardant particles and expanded graphite, and cross-linking with N,N'-methylenebisacrylamide to prepare a thermosensitive hydrogel; mixing the thermosensitive hydrogel with sodium carbonate and glacial acetic acid, and grinding them into microparticles after drying; The lanthanum organic metal framework is prepared by reacting lanthanum nitrate hexahydrate with 1,3,5-benzenetricarboxylic acid; The modified cellulose is prepared by reacting cellulose with sodium hydroxide and sodium acrylate in sequence.

2. A method for preparing a fire extinguishing agent for battery fire prevention and control, characterized in that: The method comprises the following preparation steps: (1) At room temperature, ammonium dihydrogen phosphate and deionized water were mixed at a mass ratio of 1:(2.3-2.5) to prepare a saturated ammonium dihydrogen phosphate solution, 0.3-0.4 times the mass of the lanthanum organic metal framework of the ammonium dihydrogen phosphate was added, the mixture was mixed evenly, ultrasonically dispersed for 20-30 min, anhydrous ethanol was added at 0.5-0.7 times the mass of the saturated ammonium dihydrogen phosphate solution, stirred at 10-30 ° C and 300-500 r / min for 2-3 h, allowed to stand for 1-2 h, filtered, and dried at 50-60 ° C under vacuum conditions for 5-6 h to obtain composite flame retardant particles; (2) Modified cellulose, N,N'-methylenebisacrylamide, composite flame retardant particles, expanded graphite and deionized water were mixed in a mass ratio of 1:(0.1-0.2):(0.05-0.07):(0.04-0.06):(8-10). Under nitrogen protection, 8-10% potassium persulfate aqueous solution (2-3 times the mass of modified cellulose) was added dropwise within 10 minutes. The temperature was raised to 50-60°C and stirred for 1-2 hours to obtain a thermosensitive hydrogel. Sodium carbonate (0.03-0.05 times the mass of the thermosensitive hydrogel) and glacial acetic acid (0.03-0.05 times the mass of the thermosensitive hydrogel) were added to the thermosensitive hydrogel. The mixture was stirred for 2-4 minutes. The mixture was dried at 60-70°C under vacuum for 7-9 hours. The mixture was crushed with a crusher and ground into powder with a ball mill. The powder was sieved through a 400-500 mesh sieve to obtain a fire extinguishing agent for battery fire prevention and control.

3. The method for preparing a fire extinguishing agent for battery fire prevention and control according to claim 2, characterized in that: The lanthanum organic metal framework of step (1) is prepared by uniformly mixing a lanthanum nitrate dispersion with a 1,3,5-benzenetricarboxylic acid solution, stirring at 20-30° C. and 300-500 r / min for 3-4 hours, filtering, washing with anhydrous ethanol and deionized water for 3-5 times respectively, and drying at 70-80° C. under vacuum conditions for 6-8 hours to obtain a lanthanum organic metal framework.

4. The method for preparing a fire extinguishing agent for battery fire prevention and control according to claim 3, characterized in that: The lanthanum nitrate dispersion is prepared by uniformly mixing lanthanum nitrate hexahydrate and deionized water in a mass ratio of 1:(40-50) and ultrasonically dispersing for 1-2 hours.

5. The method for preparing a fire extinguishing agent for battery fire prevention and control according to claim 3, characterized in that: The 1,3,5-benzenetricarboxylic acid solution is prepared by uniformly mixing lanthanum nitrate hexahydrate with 1,3,5-benzenetricarboxylic acid, anhydrous ethanol and deionized water in a mass ratio of 1:(20-30):(20-30).

6. The method for preparing a fire extinguishing agent for battery fire prevention and control according to claim 2, characterized in that: The modified cellulose in step (2) is prepared by uniformly mixing alkaline cellulose, potassium persulfate and deionized water in a mass ratio of 1:(0.03-0.05):(40-50), stirring at 35-45°C and 300-500 r / min for 8-10 min under nitrogen protection, adding sodium acrylate in an amount 2-3 times the mass of the alkaline cellulose, heating to 50-60°C, continuing to stir for 1-2 h, filtering, and drying at 50-60°C for 5-6 h under vacuum conditions.

7. The method for preparing a fire extinguishing agent for battery fire prevention and control according to claim 6, characterized in that: The alkaline cellulose is prepared by uniformly mixing cellulose and a sodium hydroxide aqueous solution with a mass fraction of 14-16% in a mass ratio of 1:(8-10), stirring at 50-60° C. and 300-500 r / min for 1-2 hours, cooling to room temperature, filtering, washing with deionized water for 3-5 times, and drying at 50-60° C. for 6-7 hours under vacuum conditions.

8. The method for preparing a fire extinguishing agent for battery fire prevention and control according to claim 7, characterized in that: The molecular weight of the cellulose is 80,000 to 100,000.