Lithium ion battery fire extinguishing agent and preparation process

Abstract

The application relates to the technical field of lithium ion battery fire extinguishing agents, in particular to a lithium ion battery fire extinguishing agent and a preparation process. The preparation process comprises the following steps: S1, biomass pretreatment: 40-50 parts of chitin powder is mixed with 2wt% sodium hydroxide solution according to a mass-volume ratio of 1:10, stirring is carried out at 60 DEG C for 1-2h, chitin crude products are obtained after centrifugal freeze-drying; the chitin crude products are dispersed in deionized water, and a cellulose suspension with a solid content of 1% is obtained after ultrasonic treatment; S2, cellulose modification: 15-20 parts of povidone is added to the cellulose suspension, mixing and stirring are carried out at 60 DEG C for 1h, and a modified cellulose suspension is obtained; S3, introduction of nano silicon dioxide; S4, preparation of modified gel; and S5, crosslinking and drying.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of lithium ion battery fire extinguishing agents, in particular to a lithium ion battery fire extinguishing agent and a preparation process. BACKGROUND

[0002] The types of lithium ion battery fire extinguishing agents include dry powder, gas (such as perfluorohexanone and heptafluoropropane), water-based, aerogel and the like. The cost of the gas fire extinguishing agent is relatively high, the dry powder fire extinguishing agent has a wide application range and is easy to operate, but powder residues are difficult to clean, and the cooling effect of the water-based fire extinguishing agent is remarkable, but the water-based fire extinguishing agent has strong conductivity, which has the risk of causing short circuit and corrosion of the battery. Therefore, it is necessary to develop a new type of fire extinguishing agent with high efficiency, fire extinguishing, combustion suppression and equipment protection.

[0003] In the related art, the aerogel fire extinguishing agent can quickly cool and isolate air, does not have the conductivity characteristics of the water-based fire extinguishing agent, is relatively environmentally friendly and safe, and is suitable for precision equipment and live scenes. The aerogel fire extinguishing agent usually takes inorganic or organic nanomaterials as a skeleton and combines functional fire-retardant ingredients, and mainly includes mainstream technologies of silica gel-based aerogel and graphene aerogel. On the one hand, the cost of raw materials (such as graphene) is relatively high, and on the other hand, the aerogel has relatively large brittleness, and the stability and mechanical strength are insufficient, so the aerogel is not suitable for high-temperature fire extinguishing of lithium batteries. SUMMARY

[0004] The application provides a lithium ion battery fire extinguishing agent and a preparation process to solve the problems mentioned in the background.

[0005] In a first aspect, a lithium ion battery fire extinguishing agent is provided, which comprises:

[0006] 40-50 parts of chitin powder, 15-20 parts of povidone, 20-25 parts of tetraethyl orthosilicate, 5-8 parts of a 5wt% rhamnose solution, 4-5 parts of modified attapulgite, 3-5 parts of a 25wt% glutaraldehyde solution and 5-8 parts of sodium bicarbonate;

[0007] The preparation method of the modified attapulgite comprises the following steps:

[0008] The attapulgite, perfluorohexanone and ammonium alum are mixed in a mass ratio of 2:0.5:0.1, and then ultrasonic treatment is performed for 10 minutes to obtain the modified attapulgite.

[0009] Preferably, the particle size of the attapulgite is not greater than 5μm.

[0010] In a second aspect, a preparation method of a lithium ion battery fire extinguishing agent is provided, and the preparation method is used for preparing the lithium ion battery fire extinguishing agent as any one of the above, and the preparation method comprises the following steps:

[0011] S1, biomass pretreatment:

[0012] Mix 40-50 parts of chitin powder with 2wt% sodium hydroxide solution according to the mass volume ratio 1:10, stir at 60℃ for 1-2h, centrifugal freeze-drying to obtain chitin crude product;

[0013] Disperse the chitin crude product in deionized water, and obtain a cellulose suspension with a solid content of 1% after ultrasonic treatment;

[0014] S2, cellulose modification:

[0015] Add 15-20 parts of povidone to the cellulose suspension, mix and stir at 60℃ for 1h to obtain a modified cellulose suspension;

[0016] S3, introduction of nano-silicon dioxide:

[0017] Drop 20-25 parts of tetraethyl orthosilicate into the modified cellulose suspension, adjust the pH to 2-3, then add 5-8 parts of 5wt% rhamnose solution and 10% modified attapulgite by mass of chitin, stir in an ice bath at 0-5℃ for 2h, then warm to 20-25℃ for 3h to obtain a gel;

[0018] S4, modified gel preparation:

[0019] Immerse the gel in an ethanol solution of lanolin, vacuum filter for 5-10min, and dry at 60℃ for 2h to obtain a modified gel, the concentration of the ethanol solution of lanolin is 0.5-2wt%;

[0020] S5, cross-linking and drying:

[0021] Add 3-5 parts of 25wt% glutaraldehyde solution and 5-8 parts of sodium bicarbonate to the modified gel, react in a 60℃ water bath for 3-4h to obtain a wet gel;

[0022] Use an ethanol solution to perform multiple solvent replacement of the wet gel, with a single replacement time of no less than 12h, then perform supercritical CO2 drying for 2-4h to obtain an aerogel, crush the aerogel in a ball mill to 1-80 micron powder to obtain a lithium ion battery fire extinguishing agent, the drying conditions are 40℃ and 10MPa.

[0023] Preferably, in S2, adding povidone specifically includes:

[0024] Dissolve the povidone in water at 60℃, stir until completely dissolved to obtain a 10wt% povidone solution, add the povidone solution to the cellulose suspension to obtain a modified cellulose suspension.

[0025] Preferably, in S3, glacial acetic acid is used when adjusting the pH.

[0026] Preferably, in S5, the multiple solvent replacement of the wet gel using an ethanol solution comprises the following steps:

[0027] placing the wet gel in an ethanol solution with a concentration of 95%, soaking for 12h, replacing the ethanol solution, and repeating the soaking for 2-3 times;

[0028] using anhydrous ethanol to soak for 12-24h to complete the solvent replacement.

[0029] Preferably, in S5, the supercritical CO2 drying conditions are: at room temperature, increasing the temperature to 40℃ at a rate of 2-5℃ / min, and increasing the pressure to 10MPa at a rate of 0.5-1MPa / min.

[0030] In a second aspect, a lithium ion battery extinguishing agent is provided, which is prepared by the preparation method of the lithium ion battery extinguishing agent as described in any of the above.

[0031] The technical scheme provided in the present application has the following beneficial effects:

[0032] The present application provides a preparation method of a lithium ion battery extinguishing agent, which uses chitin as a biomass-based material, has good adsorption while having certain mechanical strength, can adsorb electrolyte and assist aerogel in isolating oxygen, forms an interpenetrating network through the combination of povidone and biomass molecular chains through hydrogen bonds, improves mechanical strength and inhibits thermal decomposition, forms a hybrid structure after being combined with nano-silicon dioxide, generates CO2, N2 and a carbon layer after burning, and sodium bicarbonate decomposes to generate CO2 and Na2O, effectively extinguishing the fire while leaving no conductive residue; the modification of rhamnose and lanolin impregnation helps to form a three-dimensional network structure of aerogel, absorbs heat during decomposition, helps to cool down, improves the water resistance, thermal stability and combustion inhibition of the extinguishing agent, and has low cost, which is suitable for industrialization needs. BRIEF DESCRIPTION OF DRAWINGS

[0033] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0034] Figure 1 A flow chart of the preparation process of the lithium ion battery extinguishing agent provided in the present application. DETAILED DESCRIPTION

[0035] In order to make the purposes, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the scope of protection of the present application.

[0036] Referring to Figure 1 As shown in the drawings, the present application provides a preparation method of a lithium ion battery fire extinguishing agent, which comprises the following steps:

[0037] S1, biomass pretreatment:

[0038] 40-50 parts of chitin powder is mixed with 2wt% sodium hydroxide solution according to the mass-volume ratio of 1:10, stirred at 60℃ for 1-2h, centrifuged and freeze-dried to obtain chitin crude product;

[0039] The chitin crude product is dispersed in deionized water, and after ultrasonic treatment, a cellulose suspension with a solid content of 1% is obtained.

[0040] Further, the cellulose suspension is further ultrasonically treated to ensure uniform dispersion.

[0041] S2, cellulose modification:

[0042] 15-20 parts of povidone is added to the cellulose suspension, mixed and stirred at 60℃ for 1h to obtain a modified cellulose suspension.

[0043] Specifically, adding povidone specifically includes:

[0044] The povidone is dissolved in water at 60℃, stirred until completely dissolved to obtain a 10wt% povidone solution, and the povidone solution is added to the cellulose suspension to obtain a modified cellulose suspension.

[0045] S3, introducing nano-silicon dioxide:

[0046] 20-25 parts of tetraethyl orthosilicate is added dropwise to the modified cellulose suspension, the pH is adjusted to 2-3, 5-8 parts of 5wt% rhamnose solution and modified attapulgite with a mass of 10% of the mass of chitin are added, stirred in an ice bath at 0-5℃ for 2h, then warmed to 20-25℃ for 3h to obtain a gel.

[0047] The preparation method of the modified attapulgite comprises the following steps:

[0048] The silicate, perfluorohexanone and ammonium alum are mixed in a mass ratio of 2:0.5:0.1, and then ultrasonic treatment is performed for 10 minutes to obtain modified silicate, wherein the particle size of the silicate is not greater than 5 μm.

[0049] S4, modified gel preparation:

[0050] The gel is immersed in an ethanol solution of lanolin, vacuum filtration is performed for 5-10 minutes, and then drying is performed at 60°C for 2 hours to obtain a modified gel, wherein the concentration of the ethanol solution of lanolin is 0.5-2 wt%;

[0051] S5, cross-linking and drying:

[0052] To the modified gel, 3-5 parts of a 25 wt% glutaraldehyde solution and 5-8 parts of sodium bicarbonate are added, and then reaction is performed in a 60°C water bath for 3-4 hours to obtain a wet gel;

[0053] The wet gel is subjected to multiple solvent replacements using an ethanol solution, each replacement is performed for not less than 12 hours, and then supercritical CO2 drying is performed for 2-4 hours to obtain an aerogel, which is crushed into a 1-80 μm powder in a ball mill to obtain a lithium ion battery fire extinguishing agent, and the drying conditions are specifically 40°C and 10 MPa.

[0054] Specifically, the multiple solvent replacements of the wet gel using an ethanol solution include the following steps:

[0055] The wet gel is immersed in a 95% ethanol solution for 12 hours, the ethanol solution is replaced, and the immersion is repeated for 2-3 times;

[0056] Finally, the wet gel is immersed in anhydrous ethanol for 12-24 hours to complete the solvent replacement.

[0057] Specifically, the supercritical CO2 drying conditions are as follows: at room temperature, the temperature is increased to 40°C at a rate of 2-5°C / min, and the pressure is increased to 10 MPa at a rate of 0.5-1 MPa / min.

[0058] In the following examples and comparative examples, the preparation method of the modified silicate includes the following steps:

[0059] The silicate, perfluorohexanone and ammonium alum are mixed in a mass ratio of 2:0.5:0.1, and then ultrasonic treatment is performed for 10 minutes to obtain modified silicate, wherein the particle size of the silicate is not greater than 5 μm.

[0060] Example 1

[0061] The preparation method of the lithium ion battery fire extinguishing agent provided in this example includes:

[0062] S1, biomass pretreatment:

[0063] Mix 40 g chitin powder with 400 mL sodium hydroxide solution with a concentration of 2 wt%, stir at 60°C for 2 h, centrifugalize and freeze-dry to obtain chitin crude product; disperse the chitin crude product in deionized water, and obtain a chitin suspension with a solid content of 1% after ultrasonic treatment.

[0064] S2, chitin modification:

[0065] Dissolve 20 g povidone in water at 60°C, stir until completely dissolved to obtain a 10 wt% povidone solution, add the povidone solution to the chitin suspension prepared in S1 to obtain a modified chitin suspension.

[0066] S3, introduction of nano-silicon dioxide:

[0067] Drop 20 g tetraethyl orthosilicate into the modified chitin suspension, adjust the pH to 2 using glacial acetic acid, add 5 g of a rhamnose solution with a concentration of 5 wt%, and 4 g of modified attapulgite, stir in an ice bath at 5°C for 2 h, then warm to 25°C for 3 h to obtain a gel.

[0068] S4, preparation of modified gel:

[0069] Immerse the gel of S3 in an ethanol solution of lanolin with a concentration of 2 wt%, vacuum filter for 5 min, and dry at 60°C for 2 h to obtain a modified gel;

[0070] S5, cross-linking and drying:

[0071] Add 3 g of a glutaraldehyde solution with a concentration of 25 wt% and 5 g of sodium bicarbonate to the modified gel of S4, and react in a 60°C water bath for 4 h to obtain a wet gel;

[0072] First, use a 95% ethanol solution to perform three 12 h solvent replacements on the wet gel, then soak the wet gel in anhydrous ethanol for 12 h, then perform supercritical CO2 drying for 2 h to obtain an aerogel, which is crushed into a 1-80 micron powder in a ball mill to obtain a lithium ion battery fire extinguishing agent, with a drying condition of 40°C and 10 MPa.

[0073] Example 2

[0074] The preparation method of the lithium ion battery fire extinguishing agent provided in this example includes:

[0075] S1, biomass pretreatment:

[0076] Mix 50 g chitin powder with 500 mL sodium hydroxide solution with a concentration of 2 wt%, stir at 60°C for 1 h, centrifugalize and freeze-dry to obtain chitin crude product; disperse the chitin crude product in deionized water, and obtain a chitin suspension with a solid content of 1% after ultrasonic treatment.

[0077] S2, cellulose modification:

[0078] 20 g of povidone was dissolved in water at 60 °C, and stirred until completely dissolved to obtain a 10 wt% povidone solution. The povidone solution was added to the cellulose suspension of S1 to obtain a modified cellulose suspension.

[0079] S3, introduction of nanosilica:

[0080] 25 g of tetraethyl orthosilicate was added dropwise to the modified cellulose suspension, and the pH was adjusted to 3 using glacial acetic acid. 8 g of a rhamnose solution with a concentration of 5 wt% and 5 g of modified attapulgite were added. After stirring in an ice bath at 0 °C for 2 h, the temperature was increased to 20 °C and reacted for 3 h to obtain a gel.

[0081] S4, preparation of modified gel:

[0082] The gel of S3 was immersed in an ethanol solution of lanolin with a concentration of 1 wt%, and after vacuum filtration for 6 min, it was dried at 60 °C for 2 h to obtain a modified gel.

[0083] S5, cross-linking and drying:

[0084] 5 g of a glutaraldehyde solution with a concentration of 25 wt% and 8 g of sodium bicarbonate were added to the modified gel of S4, and reacted in a 60 °C water bath for 3 h to obtain a wet gel.

[0085] The wet gel was first subjected to two 15 h solvent exchanges using 95% ethanol solution, then soaked in anhydrous ethanol for 24 h, and then subjected to supercritical CO2 drying for 4 h to obtain an aerogel. The aerogel was crushed into a 1-80 micron powder in a ball mill to obtain a lithium ion battery fire extinguishing agent. The drying conditions were: at room temperature, the temperature was increased to 40 °C at a rate of 5 °C / min, and the pressure was increased to 10 MPa at a rate of 1 MPa / min, and the temperature and pressure were maintained at 40 °C and 10 MPa for 4 h.

[0086] Example 3

[0087] The preparation method of the lithium ion battery fire extinguishing agent provided in this example includes:

[0088] S1, biomass pretreatment:

[0089] 45 g of chitin powder was mixed with 450 mL of a 2 wt% sodium hydroxide solution, stirred at 60 °C for 2 h, and then centrifuged and freeze-dried to obtain a chitin crude product. The chitin crude product was dispersed in deionized water and ultrasonically treated to obtain a cellulose suspension with a solid content of 1%.

[0090] S2, cellulose modification:

[0091] Dissolve 15 g of povidone in water at 60 °C, stir until completely dissolved to obtain a 10 wt% povidone solution, add the povidone solution to the cellulose suspension prepared in S1 to obtain a modified cellulose suspension.

[0092] S3, introduction of nanosilica:

[0093] Add 22 g of tetraethyl orthosilicate dropwise to the modified cellulose suspension, adjust the pH to 2 using glacial acetic acid, add 6 g of a rhamnose solution with a concentration of 5 wt%, and 4.5 g of modified attapulgite, stir in an ice bath at 2 °C for 2 h, then warm to 20 °C for 3 h to obtain a gel.

[0094] S4, preparation of modified gel:

[0095] Immerse the gel of S3 in an ethanol solution of lanolin with a concentration of 0.5 wt%, vacuum suction filter for 10 min, then dry at 60 °C for 2 h to obtain a modified gel;

[0096] S5, cross-linking and drying:

[0097] Add 4 g of a glutaraldehyde solution with a concentration of 25 wt% and 6 g of sodium bicarbonate to the modified gel of S4, react in a 60 °C water bath for 3 h to obtain a wet gel;

[0098] First, perform three 12 h solvent exchanges on the wet gel using 95% ethanol solution, then soak the wet gel in anhydrous ethanol for 15 h, then perform supercritical CO2 drying for 2 h to obtain an aerogel, crush the aerogel in a ball mill to obtain a 1-80 micron powder to obtain a lithium ion battery fire extinguishing agent, the drying conditions are: at room temperature, increase the temperature to 40 °C at a rate of 2 °C / min, while increasing the pressure to 10 MPa at a rate of 0.8 MPa / min, and maintain drying at 40 °C and 10 MPa for 2 h.

[0099] Example 4

[0100] The preparation method of the lithium ion battery fire extinguishing agent provided in this example comprises:

[0101] S1, biomass pretreatment:

[0102] Mix 45 g of chitin powder with 450 mL of a 2 wt% sodium hydroxide solution, stir at 60 °C for 1 h, centrifuge and freeze-dry to obtain chitin crude product; disperse the chitin crude product in deionized water, ultrasonically treat to obtain a cellulose suspension with a solid content of 1%.

[0103] S2, cellulose modification:

[0104] Dissolve 18 g of povidone in water at 60 °C, stir until completely dissolved to obtain a 10 wt% povidone solution, add the povidone solution to the cellulose suspension prepared in S1 to obtain a modified cellulose suspension.

[0105] S3, introduction of nanosilica:

[0106] Add 25 g of tetraethyl orthosilicate dropwise to the modified cellulose suspension, adjust the pH to 2 using glacial acetic acid, add 6 g of a rhamnose solution with a concentration of 5 wt%, and 4.5 g of modified attapulgite, stir in an ice bath at 2 °C for 2 h, then warm to 25 °C for 3 h to obtain a gel.

[0107] S4, preparation of modified gel:

[0108] Immerse the gel of S3 in an ethanol solution of lanolin with a concentration of 1 wt%, vacuum suction filter for 6 min, then dry at 60 °C for 2 h to obtain a modified gel;

[0109] S5, crosslinking and drying:

[0110] Add 4 g of a glutaraldehyde solution with a concentration of 25 wt% and 6 g of sodium bicarbonate to the modified gel of S4, react in a 60 °C water bath for 3 h to obtain a wet gel;

[0111] First, perform three solvent exchanges of the wet gel using 95% ethanol solution for 12 h each, then soak the wet gel in anhydrous ethanol for 15 h, then perform supercritical CO2 drying for 2 h to obtain an aerogel, crush the aerogel into a 1-80 micron powder in a ball mill to obtain a lithium ion battery extinguishing agent, the drying conditions are: at room temperature, increase the temperature to 40 °C at a rate of 4 °C / min, while increasing the pressure to 10 MPa at a rate of 0.8 MPa / min, and maintain drying at 40 °C and 10 MPa for 2 h.

[0112] Comparative Example 1

[0113] The difference between this comparative example and Example 4 is that the S2 step is not performed.

[0114] Comparative Example 2

[0115] The difference between this comparative example and Example 4 is that in step S2, the amount of povidone added is reduced to 5 g.

[0116] Comparative Example 3

[0117] The difference between this comparative example and Example 4 is that in step S3, no rhamnose solution is added.

[0118] Comparative Example 4

[0119] The difference between the present comparative example and Example 4 is that the S4 step is not performed.

[0120] A 1 Ah lithium iron phosphate battery (18650 specification) was used as the test object:

[0121] The fire extinguishing efficiency was tested. The lithium ion battery extinguishing agent prepared in Examples 1 to 4 and Comparative Examples 1 to 4 was filled into a spray gun, the filling pressure was 1.5 MPa (20°C), the spray head pressure was 1.2 MPa, and the spray head outlet diameter was 3 mm; five lithium batteries were used as a group, and after being fully charged, they were placed in a fireproof container, and the current and voltage were gradually increased to overcharge the batteries. When the batteries started to heat up, smoke, and eventually appeared as a flame, a small lithium ion battery fire was successfully ignited. The extinguishing agent was sprayed 2 seconds after the flame appeared, and the spray head was 1 m away from the surface of the battery. A high-speed camera and an infrared thermal imager were used to record the changes in flame and temperature after the battery thermal runaway. The time from thermal runaway to complete flame extinguishment was recorded, and the results are shown in Table 1.

[0122] Table 1

[0123] Group Extinguishing time (s) Example 1 6.3 Example 2 5.2 Example 3 5.4 Example 4 4.5 Comparative Example 1 6.5 Comparative Example 2 7.6 Comparative Example 3 8.3 Comparative Example 4 8.8

[0124] As can be seen from the above table, the fire extinguishing time of the lithium ion battery extinguishing agent prepared in Examples 1 to 4 is within 7 seconds. This is because the aerogel has good heat insulation performance and coverage effect, which quickly blocks the contact between the battery and oxygen, inhibits the combustion reaction, and there is no rekindling phenomenon within 24 hours. Compared with Comparative Example 4, Example 4 has a faster fire extinguishing time. This is because the modification of lanolin gives the aerogel a certain flexibility, and the hydrophobic groups of lanolin reduce the polarity of the extinguishing agent.

[0125] Further, the mechanical strength was tested. The aerogels prepared in Examples 1 to 4 and Comparative Examples 1 to 4 were processed into cylindrical samples with a diameter of 10 mm and a height of 20 mm. The samples were placed between the upper and lower compression plates of a material testing machine, which were coated with silicone oil to prevent sticking. Then the samples were compressed at a compression rate of 0.5 mm / min until the strain reached 50%. According to the stress-strain curve, the corresponding elastic modulus and compressive strength were obtained. The results are shown in Table 2.

[0126] Table 2

[0127]

[0128]

[0129] The lithium battery generates thermal expansion stress when thermal runaway occurs. The fire extinguishing agent with certain mechanical strength can maintain the structural integrity at high temperature and continuously play a role. The aerogels prepared in Examples 1-4 have high elastic modulus and compressive strength, which can ensure that the fire extinguishing agent is not easily damaged in the lithium battery thermal runaway environment, can withstand certain high temperature expansion stress, and maintain its heat insulation and fire extinguishing performance.

[0130] The anti-caking property of the lithium ion battery fire extinguishing agent obtained from Examples 1-4 and Comparative Examples 1-4 was tested according to GB 15308-2019. 50g of lithium ion battery fire extinguishing agent powder was loaded into an aluminum can, stored at 50℃ and 75% humidity for 72h, then cooled to room temperature, and the surface hardness of the powder was tested using a needle penetration tester. Examples 1-4 and Comparative Examples 1-4 did not show obvious caking.

[0131] The above is only a specific embodiment of the present application, which enables those skilled in the art to understand or implement the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to these embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features applied herein.

Claims

1. A fire extinguishing agent for lithium ion batteries, characterized by comprising: It comprises: 40~50 parts of chitin powder, 15~20 parts of povidone, 20~25 parts of tetraethyl orthosilicate, 5~8 parts of 5wt% rhamnose solution, 4~5 parts of modified attapulgite, 3~5 parts of 25wt% glutaraldehyde solution and 5~8 parts of sodium bicarbonate; The preparation method of the modified attapulgite comprises the following steps: After mixing the attapulgite, perfluorohexanone and ammonium alum according to the mass ratio of 2:0.5:0.1, ultrasonic treatment is carried out for 10 min to obtain the modified attapulgite; The preparation method of the lithium ion battery fire extinguishing agent comprises the following steps: S1, biomass pretreatment: After mixing 40~50 parts of chitin powder with 2wt% sodium hydroxide solution according to the mass volume ratio of 1:10, stirring at 60℃ for 1~2h, centrifugal freeze-drying, chitin crude product is obtained; The chitin crude product is dispersed in deionized water, and after ultrasonic treatment, a cellulose suspension with a solid content of 1% is obtained; S2, cellulose modification: 15~20 parts of povidone are added to the cellulose suspension, mixed and stirred at 60℃ for 1h to obtain a modified cellulose suspension; S3, introduction of nano silicon dioxide: 20~25 parts of tetraethyl orthosilicate are added to the modified cellulose suspension, the pH is adjusted to 2~3, 5~8 parts of 5wt% rhamnose solution and modified attapulgite with a mass of 10% of chitin are added, stirring in an ice bath at 0~5℃ for 2h, then warming to 20~25℃ for 3h to obtain a gel; S4, preparation of modified gel: The gel is immersed in lanolin ethanol solution, vacuum filtration for 5~10min, and dried at 60℃ for 2h to obtain a modified gel, the concentration of the lanolin ethanol solution is 0.5~2wt%; S5, crosslinking and drying: 3~5 parts of 25wt% glutaraldehyde solution and 5~8 parts of sodium bicarbonate are added to the modified gel, and the reaction is carried out in a 60℃ water bath for 3~4h to obtain a wet gel; The wet gel is subjected to multiple solvent replacement with ethanol solution, and each replacement time is not less than 12h, then supercritical CO2 drying is carried out for 2~4h to obtain an aerogel, the aerogel is crushed into 1~80 micron powder in a ball mill to obtain a lithium ion battery fire extinguishing agent, and the drying conditions are 40℃ and 10MPa.

2. The lithium ion battery fire extinguishing agent of claim 1, wherein: The particle size of the attapulgite is not greater than 5μm.

3. The lithium ion battery fire extinguishing agent of claim 1, wherein: In S2, the addition of povidone specifically comprises: The povidone is dissolved in water at 60℃, stirred until completely dissolved to obtain a 10wt% povidone solution, and the povidone solution is added to the cellulose suspension to obtain a modified cellulose suspension.

4. The lithium ion battery fire extinguishing agent of claim 1, wherein: In S3, glacial acetic acid is used when adjusting the pH.

5. The lithium ion battery fire extinguishing agent of claim 1, wherein: In S5, the multiple solvent replacement of the wet gel with ethanol solution comprises the following steps: The wet gel is placed in an ethanol solution with a concentration of 95% for 12 hours, the ethanol solution is replaced, and the soaking is repeated 2-3 times; Anhydrous ethanol is used for soaking for 12-24 hours to complete solvent replacement.

6. The lithium ion battery fire extinguishing agent according to claim 1, wherein: In S5, the supercritical CO2 drying conditions are: at room temperature, the temperature is increased to 40℃ at a rate of 2-5℃ / min, and the pressure is increased to 10 MPa at a rate of 0.5-1 MPa / min.

Images