A cellulose-based aerogel battery core thermal insulation material and a preparation method thereof

Abstract

The present application relates to the technical field of battery core thermal insulation sheets and their preparation, and in particular to a cellulose-based aerogel battery core thermal insulation material and its preparation method. The cellulose-based aerogel battery core thermal insulation material provided by the method includes: a first glass fiber mesh cloth; a first cellulose-based aerogel composite slurry layer coated on the first surface of the first fiber mesh cloth; a second cellulose-based aerogel composite slurry layer coated on the second surface of the first fiber mesh cloth; a first release film covering the first cellulose-based aerogel composite slurry layer; a second release film covering the second cellulose-based aerogel composite slurry layer. The thermal insulation sheet prepared by the method of the present application has good thermal insulation performance, flame retardancy, thermal stability, mechanical properties and safety, etc.; the method of the present invention also has the advantages of simple and easy operation of the preparation method, fewer types of raw materials used, and low preparation cost.

Description

Technical Field

[0001] The present application relates to the technical field of battery core thermal insulation sheets and preparation thereof, and in particular to a cellulose-based aerogel battery core thermal insulation material and a preparation method thereof. Background Art

[0002] Insulation materials in the new energy field include fiber felt, foam, mica board and aerogel materials. In recent years, aerogel materials have been widely studied and applied, and have been proven to have many advantages as insulation materials. In the field of new energy vehicles, aerogel materials are used not only for thermal insulation and shockproofing of the vehicle body, modules and shells, external cold-proof layers and high-temperature insulation layers of battery boxes, but also for thermal insulation and flame retardancy between power battery cells. At present, electric vehicles mainly use lithium-ion batteries as power batteries, and battery thermal runaway under extreme conditions brings safety problems to electric vehicles, such as electric vehicles catching fire due to overcharging of the battery. In this case, aerogel battery cell insulation sheets are used between battery cells and modules to play a role in thermal isolation, which can better prevent safety accidents caused by thermal runaway of the battery cells.

[0003] Currently, commonly used aerogel materials, such as silicone gel felt, have good thermal insulation performance and certain heat resistance and fire resistance, and have good application prospects. Researchers have conducted a lot of research on this related technology, and it has been proven that good results have been achieved. For example, Chinese patent application CN 114883736A (under review) discloses an aerogel battery core thermal insulation sheet and its preparation method and application. It prepares an aerogel battery core thermal insulation sheet by compounding glass fiber mesh cloth, aerogel composite slurry and glass fiber felt. The thermal insulation sheet has high strength, is not easy to deform, and has good thermal stability. However, the composition of this method is complex. In addition to the complex mixing process and high preparation cost, there is also the problem of insufficient mechanical properties.

[0004] In addition, due to the existing problems of poor mechanical properties, high preparation cost, insufficient thermal stability and fire resistance of aerogels, it is increasingly difficult to meet the current technological development demand for battery core insulation materials. Therefore, reducing the preparation cost of aerogel materials and further improving the properties of aerogel insulation materials, including heat resistance, flame retardancy, mechanics, etc., have always been the hot spots and difficulties of industry research. Summary of the invention

[0005] The embodiments of the present application provide a cellulose-based aerogel battery core thermal insulation material and a preparation method thereof, so as to solve the problems of the aerogel battery core thermal insulation material in the related art, such as insufficient flame retardancy and heat resistance, poor mechanical properties, and high preparation cost.

[0006] In a first aspect, a cellulose-based aerogel battery core thermal insulation material is provided, comprising:

[0007] Fiberglass mesh cloth;

[0008] a first cellulose-based aerogel composite slurry layer coated on a first surface of the glass fiber mesh cloth;

[0009] a second cellulose-based aerogel composite slurry layer coated on the second surface of the glass fiber mesh cloth;

[0010] A first release film covering the first cellulose-based aerogel composite slurry layer;

[0011] A second release film is covered on the second cellulose-based aerogel composite slurry layer.

[0012] Specifically, the release film is a PE film, a PET film, an OPP film or a PI film.

[0013] In a second aspect, a method for preparing the above-mentioned cellulose-based aerogel battery core thermal insulation material is provided, comprising the following steps:

[0014] Step 1: preparing a cellulose-based aerogel composite slurry;

[0015] Step 2: Apply a layer of cellulose-based aerogel composite slurry on the second surface of the glass fiber mesh cloth, covering the first release film;

[0016] Step 3: Apply a layer of cellulose-based aerogel composite slurry on the second surface of the glass fiber mesh cloth, covering the second release film;

[0017] Step 4: Dry naturally at room temperature or in an oven and then remove the film to obtain a cellulose-based aerogel battery cell thermal insulation sheet.

[0018] Specifically, the process of preparing the cellulose-based aerogel composite slurry in step 1 is as follows:

[0019] To prepare cellulose-based aerogel, water, silicone-acrylic emulsion, cellulose-based aerogel, defoamer, preservative, glass microbeads and chopped fibers are mixed in proportion.

[0020] More specifically, the cellulose-based aerogel battery core insulation material provided includes the following components by weight percentage:

[0021] Water 10-25%, silicone-acrylic emulsion 26-42%, cellulose-based aerogel 10-25%, defoaming agent 0.3-2%, preservative 0.2-1.2%, glass microbeads 4-7%, chopped fibers 5-16%.

[0022] More specifically, the defoamer is selected from one of the polysiloxane defoamers; the polysiloxane defoamers include but are not limited to Z-201 and XST-1340 (manufacturer: Fujian Xister Environmental Protection Materials Technology Co., Ltd.);

[0023] More specifically, the preservative includes but is not limited to at least one of S-100 and S-133, both of which are purchased from Guangzhou Zhongwan New Materials Co., Ltd.

[0024] More specifically, the chopped fibers are at least one of glass fibers, carbon fibers, pre-oxidized fibers and aluminum silicate fibers, and the length of the chopped fibers is 1.5 to 100 mm.

[0025] More specifically, the method for preparing the cellulose-based aerogel comprises:

[0026] Step 1, dissolving cellulose in an acid solution and adding a cross-linking agent to react;

[0027] Step 2, adding a dispersion of phosphoethanolamine to react;

[0028] Step 3: Finally, after gel aging and supercritical drying, a cellulose-based aerogel battery core thermal insulation material is obtained.

[0029] During the preparation process of the above-mentioned cellulose-based aerogel, silica sol is added as a cross-linking agent to connect and form a three-dimensional network structure and introduce a large number of silicon hydroxyl groups, and then phosphoethanolamine is added to cross-link and stabilize the gel structure, form a rich pore structure, and introduce carbon chains and phosphate groups on the surface of the cellulose-based aerogel. Therefore, the prepared cellulose-based aerogel has good thermal insulation performance, structural stability, thermal stability, and mechanical properties, and the surface also has a certain hydrophobicity; in addition, since the added cross-linking agent first consumes the hydroxyl groups on the cellulose, and the remaining hydroxyl groups consume the hydroxyl groups on the phosphoethanolamine, the water absorption of the prepared cellulose-based aerogel is greatly improved, and the safety of the battery core thermal insulation material used for preparation is improved; the method of the present invention also has the advantages of simple and easy operation of the preparation method, low preparation of raw materials used, and low preparation cost.

[0030] Specifically, the cellulose in step 1 is hydroxy cellulose;

[0031] More specifically, the hydroxycellulose is selected from at least one of hydroxymethyl cellulose, hydroxyethyl cellulose, carboxymethyl cellulose and carboxyethyl cellulose; the selection of hydroxycellulose is conducive to better gel formation.

[0032] Specifically, in step 1, the concentration of cellulose in the acid solution is 1-5 wt%, and the pH is 4.0-6.0.

[0033] Specifically, the acid solution in step 1 is a hydrochloric acid solution.

[0034] Specifically, the crosslinking agent in step 1 is silica sol, and the mass fraction of the silica sol is 15-30%; the silica sol contains a large amount of silanol groups, has high reactivity, and can react with hydroxyl groups, amino groups and the like.

[0035] Specifically, the reaction temperature in step 1 is 40 to 80° C., and the reaction time is 4 to 24 hours.

[0036] Specifically, the mass ratio of cellulose to cross-linking agent added in step 1 is 12 to 21:1.

[0037] Specifically, the mass ratio of the phosphoethanolamine added in step 2 to the silica sol added in step 1 is 1 to 3:1;

[0038] The amino group of phosphoethanolamine can react with the hydroxyl group to produce cross-linking. The carbon chain it contains can form a hydrophobic layer on the surface of cellulose-based aerogel, and the phosphate group at its end is beneficial to improving flame retardancy and temperature resistance.

[0039] The content of phosphoethanolamine should not exceed this ratio, because the phosphate group it contains is a hydrophilic group. When the content of phosphoethanolamine exceeds this ratio, the prepared cellulose-based aerogel battery core insulation material will absorb a large amount of water, which will not only affect the structural stability, but also may cause safety hazards; when its content is too low, it is not conducive to cross-linking and the consumption of the introduced silanol groups, and will also cause the prepared cellulose-based aerogel battery core insulation material to absorb water.

[0040] Specifically, the reaction temperature in step 2 is 40-60° C., and the reaction time is 0.5-1 h.

[0041] Specifically, in the dispersion of phosphoethanolamine in step 2, the content of phosphoethanolamine is more than 10%; the dispersion of phosphoethanolamine is added in this process to facilitate uniform dispersion, which can also be achieved by adding powder and stirring sufficiently.

[0042] Specifically, the supercritical drying conditions in step 3 are to maintain a pressure of 13 to 18 MPa at 50 to 70° C. and a drying time of 20 to 24 hours.

[0043] Specifically, the gel aging condition in step 3 is standing at room temperature for 6 to 24 hours.

[0044] Specifically, step 3 also includes a solvent replacement step.

[0045] Specifically, step 3 also includes a step of performing hydrophobic modification.

[0046] The beneficial effects of the technical solution provided by this application include:

[0047] (1) The cellulose-based aerogel battery core thermal insulation sheet provided by the present invention contains cellulose-based aerogel, which has good dispersibility and low water absorption in both aqueous and oily systems, and is easy to add in large quantities. In addition, the aerogel is cross-linked with silica sol and phosphoethanolamine during the preparation process, and has good mechanical properties and structural stability. The cellulose-based aerogel battery core thermal insulation sheet prepared using the aerogel has excellent thermal insulation, flame retardancy, heat resistance, mechanical properties and safety.

[0048] (2) The cellulose-based aerogel battery cell insulation sheet provided by the present invention contains relatively few types of components, which reduces the preparation cost of aerogel battery cell insulation materials; the method of the present application also has the advantages of being simple and easy to operate, requiring less equipment investment, being conducive to mass production, and having good application prospects. DETAILED DESCRIPTION

[0049] The technical solution of the present application will be described clearly and completely below in conjunction with the embodiments. Obviously, the described embodiments are part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0050] The silicone-acrylic emulsions used in the examples and comparative examples of the present application were produced by Linyi Haishan Chemical Co., Ltd.; the defoamers Z-201 and XST-1340 used were produced by Fujian Xister Environmental Protection Materials Technology Co., Ltd.; the preservatives S-100 and S-133 used were purchased from Guangzhou Zhongwan New Materials Co., Ltd.

[0051] Example 1

[0052] 1. A method for preparing a cellulose-based aerogel battery core thermal insulation material, comprising:

[0053] Step 1, dissolving hydroxymethyl cellulose in a hydrochloric acid solution to a pH of 5 and a cellulose concentration of 3 wt % in the hydrochloric acid solution, adding silica sol (silicon dioxide content of 25 wt %) as a crosslinking agent at a mass ratio of cellulose to crosslinking agent of 15:1, and reacting at 60° C. for 12 h;

[0054] Step 2, adding a dispersion of phosphoethanolamine (15 wt%) at a mass ratio of phosphoethanolamine to silica sol of 2:1 and reacting at 50° C. for 45 min;

[0055] Step 3: Finally, the mixture was allowed to stand at room temperature for 18 hours for gel aging and supercritically dried for 22 hours at 60° C. and 15 MPa using carbon dioxide as a medium to obtain a cellulose-based aerogel battery core insulation material.

[0056] 2. Preparation method of cellulose-based aerogel battery core insulation material:

[0057] Step 1: Prepare cellulose-based aerogel composite slurry by taking 17 parts of water, 42 parts of silicone-acrylic emulsion, 18 parts of cellulose-based aerogel, 1 part of defoamer Z-201, 1 part of preservative S-100, 5 parts of glass microbeads and 16 parts of 50mm glass fiber in proportion;

[0058] Step 2: Apply a layer of cellulose-based aerogel composite slurry on the second surface of the glass fiber mesh cloth and cover it with a PE film;

[0059] Step 3: Apply a layer of cellulose-based aerogel composite slurry on the second surface of the glass fiber mesh cloth and cover it with a PE film;

[0060] Step 4: After naturally drying at room temperature, remove the film to obtain a cellulose-based aerogel battery cell thermal insulation sheet.

[0061] Example 2

[0062] 1. A method for preparing a cellulose-based aerogel battery core thermal insulation material, comprising:

[0063] Step 1, dissolving hydroxyethyl cellulose in a hydrochloric acid solution to a pH of 4.0 and a cellulose concentration of 2 wt % in the hydrochloric acid solution, adding silica sol (silicon dioxide content of 16 wt %) as a crosslinking agent at a mass ratio of cellulose to crosslinking agent of 12:1, and reacting at 40° C. for 24 h;

[0064] Step 2, adding a dispersion of phosphoethanolamine (25 wt%) at a mass ratio of phosphoethanolamine to silica sol of 1:1 and reacting at 40° C. for 0.5 h;

[0065] Step 3: Finally, the mixture was allowed to stand at room temperature for 8 hours for gel aging and supercritically dried at 50° C. and 18 MPa for 24 hours using carbon dioxide as a medium to obtain a cellulose-based aerogel battery core insulation material.

[0066] 2. Preparation method of cellulose-based aerogel battery core insulation material:

[0067] Step 1: Prepare cellulose-based aerogel composite slurry by taking 25 parts of water, 42 parts of silicone-acrylic emulsion, 15 parts of cellulose-based aerogel, 0.5 parts of defoamer XST-1340, 0.5 parts of preservative S-133, 7 parts of glass microbeads and 10 parts of 95mm carbon fiber in proportion;

[0068] Step 2: Apply a layer of cellulose-based aerogel composite slurry on the second surface of the glass fiber mesh cloth, and cover it with a PET film;

[0069] Step 3: Apply a layer of cellulose-based aerogel composite slurry on the second surface of the glass fiber mesh cloth, covering the PET film;

[0070] Step 4: Dry in an oven at room temperature and then remove the film to obtain a cellulose-based aerogel battery cell thermal insulation sheet.

[0071] Example 3

[0072] 1. A method for preparing a cellulose-based aerogel battery core thermal insulation material, comprising:

[0073] Step 1, dissolving carboxymethyl cellulose in a hydrochloric acid solution to a pH of 6.0 and a cellulose concentration of 4 wt % in the hydrochloric acid solution, adding silica sol (silicon dioxide content of 28 wt %) as a crosslinking agent at a mass ratio of cellulose to crosslinking agent of 21:1, and reacting at 80° C. for 4 h;

[0074] Step 2, adding a dispersion of phosphoethanolamine (12 wt%) at a mass ratio of phosphoethanolamine to silica sol of 1 to 3:1 and reacting at 60° C. for 0.5 h;

[0075] Step 3: Finally, the gel is allowed to stand at room temperature for 24 hours for gel aging, and then the solvent is replaced three times with n-hexane as the solvent, and then supercritically dried with carbon dioxide as the medium at 70° C. and a pressure of 13 MPa for 20 hours to obtain a cellulose-based aerogel battery core insulation material.

[0076] 2. Preparation method of cellulose-based aerogel battery core insulation material:

[0077] Step 1: Prepare a cellulose-based aerogel composite slurry by taking 25 parts of water, 26 parts of silicone-acrylic emulsion, 25 parts of cellulose-based aerogel, 1.8 parts of defoamer Z-201, 1.2 parts of preservative S-100, 6 parts of glass microbeads and 15 parts of 5 mm pre-oxidized silk fibers in proportion;

[0078] Step 2: Apply a layer of cellulose-based aerogel composite slurry on the second surface of the glass fiber mesh cloth, covering the OPP film;

[0079] Step 3: Apply a layer of cellulose-based aerogel composite slurry on the second surface of the glass fiber mesh cloth, covering the OPP film;

[0080] Step 4: After naturally drying at room temperature, remove the film to obtain a cellulose-based aerogel battery cell thermal insulation sheet.

[0081] Example 4

[0082] 1. A method for preparing a cellulose-based aerogel battery core thermal insulation material, comprising:

[0083] Step 1, dissolving carboxyethyl cellulose in a hydrochloric acid solution to a pH of 4.0 and a cellulose concentration of 2 wt % in the hydrochloric acid solution, adding silica sol (silicon dioxide content of 21 wt %) as a crosslinking agent at a mass ratio of cellulose to crosslinking agent of 18:1, and reacting at 60° C. for 4 h;

[0084] Step 2, adding phosphoethanolamine at a mass ratio of phosphoethanolamine to silica sol of 2:1 and reacting at 50° C. for 40 minutes;

[0085] Step 3: Finally, the mixture was allowed to stand at room temperature for 12 hours for gel aging, and then immersed in a 10 wt% hexamethyldisilazane solution for hydrophobic modification, and then supercritically dried at 60°C and 15 MPa for 24 hours with carbon dioxide as the medium to obtain a cellulose-based aerogel battery core insulation material.

[0086] 2. Preparation method of cellulose-based aerogel battery core insulation material:

[0087] Step 1: Prepare cellulose-based aerogel composite slurry by taking 18.5 parts of water, 38 parts of silicone-acrylic emulsion, 21 parts of cellulose-based aerogel, 0.3 parts of defoamer Z-201, 0.2 parts of preservative S-100, 7 parts of glass microbeads and 15 parts of 15mm aluminum silicate fiber in proportion;

[0088] Step 2: Apply a layer of cellulose-based aerogel composite slurry on the second surface of the glass fiber mesh cloth to cover the PI film;

[0089] Step 3: Apply a layer of cellulose-based aerogel composite slurry on the second surface of the glass fiber mesh cloth to cover the PI film;

[0090] Step 4: After naturally drying at room temperature, remove the film to obtain a cellulose-based aerogel battery cell thermal insulation sheet.

[0091] Comparative Example 1

[0092] Preparation method of aerogel battery core thermal insulation material:

[0093] Step 1: Prepare cellulose-based aerogel composite slurry by taking 17 parts of water, 42 parts of silicone-acrylic emulsion, 18 parts of silicone aerogel (manufacturer: Jiangxi Chenguang New Materials Co., Ltd.), 1 part of defoamer Z-201, 1 part of preservative S-100, 5 parts of glass microbeads and 16 parts of 50mm glass fiber in proportion;

[0094] Step 2: Apply a layer of cellulose-based aerogel composite slurry on the second surface of the glass fiber mesh cloth and cover it with a PE film;

[0095] Step 3: Apply a layer of cellulose-based aerogel composite slurry on the second surface of the glass fiber mesh cloth and cover it with a PE film;

[0096] Step 4: After naturally drying at room temperature, remove the film to obtain the aerogel battery cell thermal insulation sheet.

[0097] Comparative Example 2

[0098] The preparation method of cellulose aerogel battery core thermal insulation material is as follows:

[0099] Step 1: Prepare cellulose-based aerogel composite slurry by taking 17 parts of water, 42 parts of silicone-acrylic emulsion, 18 parts of cellulose aerogel, 1 part of defoamer Z-201, 1 part of preservative S-100, 5 parts of glass microbeads and 16 parts of 50mm glass fiber in proportion;

[0100] Step 2: Apply a layer of cellulose-based aerogel composite slurry on the second surface of the glass fiber mesh cloth and cover it with a PE film;

[0101] Step 3: Apply a layer of cellulose-based aerogel composite slurry on the second surface of the glass fiber mesh cloth and cover it with a PE film;

[0102] Step 4: After naturally drying at room temperature, remove the film to obtain the cellulose aerogel battery core thermal insulation sheet.

[0103] The preparation method of cellulose aerogel in this comparative example refers to Example 1 of CN107686562A, specifically:

[0104] Weigh 400g of poplar wood and put it into a plant crusher, grind it for 1h, pass it through a 60-mesh standard sieve to obtain sieved powder, weigh 10g of the sieved powder and put it into a Soxhlet extractor, mix phenylethanol and water at a volume ratio of 2:1 at room temperature to obtain a phenylethanol solution, then pour 300mL of the phenylethanol solution into the Soxhlet extractor, extract it at 90℃ for 6h, remove the extract, and obtain a crude cellulose; put the crude cellulose into a beaker, add 50mL of 20% by mass subchloroethane into the beaker, and sodium hydroxide solution, adjust the pH value of the solution to 4 with 98% glacial acetic acid, keep warm at 75°C for 5h, repeat the above operation 3 times, remove lignin and obtain holocellulose; soak the holocellulose with 120mL of 20% sodium hydroxide solution at 90°C, keep warm for 2h, filter and remove the filtrate to obtain purified cellulose, prepare the purified cellulose into a 10% water suspension, place it in an ultrasonic plant cell crusher and ultrasonically treat it at a power of 1200W for 30min to obtain wood nanocellulose; according to weight, mix 10 parts of 25% silica sol, 4 parts of 5% nitric acid solution and 16 parts of anhydrous ethanol and add them to a beaker, stir for 15min to obtain a mixed solution, add 100 parts of n-heptane, 4 parts of n-butanol and 0.1 parts of sucrose ester to a three-necked flask, and drop the mixed solution into the three-necked flask with a constant pressure dropping funnel at a dropping rate of 3mL / min, and start the stirrer at the same time , after stirring at 100 r / min for 30 min, 4 parts of 5% ammonia water by mass and 30 parts of wood nanocellulose were added, and after waiting for 10 min, the substance in the flask was filtered to obtain a filter cake; the filter cake was washed 3 times with acetone to obtain gel microspheres, and at 60 ° C, ethyl orthosilicate and anhydrous ethanol were mixed in a mass ratio of 1:3 to obtain a mixture, and the gel microspheres were soaked in the mixture for 3 h and then dried at 70 ° C at normal pressure for 1 h to obtain cellulose aerogel microspheres.

[0105] Performance Testing

[0106] The performance of the thermal insulation sheets prepared in the examples and comparative examples was tested, and the test results are shown in Table 1. The thermal insulation performance test of the obtained cellulose-based aerogel battery core thermal insulation material was carried out in accordance with the GB / T34336-2017 standard.

[0107] Table 1

[0108]

[0109] It can be seen from Table 1 that the cellulose-based aerogel battery core insulation material prepared in the embodiment of the present invention has good thermal insulation performance, flame retardant performance, mechanical properties and thermal stability; in addition, in Comparative Example 1, the cellulose-based aerogel is replaced by silica aerogel, and in Comparative Example 2, the cellulose-based aerogel prepared in the present application is replaced by the existing cellulose aerogel. Since the surfaces of the silica aerogel and the existing cellulose aerogel are not treated with silica sol and phosphoethanolamine, the structure is easily destroyed after being dispersed and infiltrated in the resin and organic solvent systems, and it is difficult to disperse in both water and oil systems. The large amount of addition leads to uneven mixing. The thermal insulation performance, flame retardant performance, mechanical properties and thermal stability of the aerogel battery core insulation sheet finally prepared are poor.

Claims

1. A cellulose-based aerogel battery core insulation material, characterized in that: include: Fiberglass mesh cloth; a first cellulose-based aerogel composite slurry layer coated on a first surface of the glass fiber mesh cloth; a second cellulose-based aerogel composite slurry layer coated on the second surface of the glass fiber mesh cloth; A first release film covering the first cellulose-based aerogel composite slurry layer; a second release film covering the second cellulose-based aerogel composite slurry layer; The preparation method of the cellulose-based aerogel battery core thermal insulation material comprises: preparing a cellulose-based aerogel composite slurry, wherein the process of preparing the cellulose-based aerogel composite slurry is: Prepare cellulose-based aerogel, mix water, silicone-acrylic emulsion, cellulose-based aerogel, defoamer, preservative, glass microbeads and chopped fibers in proportion; The preparation method of the cellulose-based aerogel comprises: Step 1, dissolving cellulose in an acid solution and adding a cross-linking agent to react; Step 2, adding a dispersion of phosphoethanolamine to react; The cross-linking agent in step 1 is silica sol.

2. The cellulose-based aerogel battery core thermal insulation material according to claim 1, characterized in that: The release film is a PE film, a PET film, an OPP film or a PI film.

3. A method for preparing the cellulose-based aerogel battery core thermal insulation material according to claim 1, characterized in that: The following steps are involved: Step 1: Apply a layer of cellulose-based aerogel composite slurry on the second surface of the glass fiber mesh cloth, covering the first release film; Step 2: Apply a layer of cellulose-based aerogel composite slurry on the second surface of the glass fiber mesh cloth, covering the second release film; Step 3: Dry naturally at room temperature or in an oven and then remove the film to obtain a cellulose-based aerogel battery cell thermal insulation sheet.

4. The cellulose-based aerogel battery core thermal insulation material according to claim 1, characterized in that: The chopped fibers are at least one of glass fibers, carbon fibers, pre-oxidized fibers and aluminum silicate fibers, and the length of the chopped fibers is 1.5 to 100 mm.

5. The cellulose-based aerogel battery core thermal insulation material according to claim 1, characterized in that: The cellulose-based aerogel composite slurry comprises the following components by weight percentage: Water 10-25%, silicone-acrylic emulsion 26-42%, cellulose-based aerogel 10-25%, defoaming agent 0.3-2%, preservative 0.2-1.2%, glass microbeads 4-7%, chopped fibers 5-16%.

6. The cellulose-based aerogel battery core thermal insulation material according to claim 1, characterized in that: The method for preparing the cellulose-based aerogel further comprises: After the reaction in step 2, the cellulose-based aerogel is obtained by gel aging and supercritical drying.

7. The cellulose-based aerogel battery core thermal insulation material according to claim 1, characterized in that: The cellulose in step 1 is selected from at least one of hydroxymethyl cellulose, hydroxyethyl cellulose, carboxymethyl cellulose and carboxyethyl cellulose.

8. The cellulose-based aerogel battery core thermal insulation material according to claim 1, characterized in that: The mass fraction of the silica sol is 15-30%.

9. The cellulose-based aerogel battery core thermal insulation material according to claim 1, characterized in that: The mass ratio of the cellulose added in step 1 to the cross-linking agent is 12-21:1, and the mass ratio of the phosphoethanolamine added in step 2 to the cross-linking agent added in step 1 is 1-3:1.

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