Composite phase change heat storage coating for new energy battery and preparation method of composite phase change heat storage coating

Abstract

The invention relates to a composite phase change heat storage coating for a new energy battery and a preparation method of the composite phase change heat storage coating. According to the technical scheme, the preparation method comprises the following steps: mixing silicon carbide, diamond, alumina sol, sodium carboxymethyl cellulose, polyacrylamide and a defoaming agent to obtain slurry I; and mixing the slurry I with polyisocyanate to prepare the high-thermal-conductivity internal coating. Uniformly mixing sodium sulfate decahydrate, n-eicosane and diatomite to obtain a phase change microcapsule; mixing the phase change microcapsules, alumina sol, sodium carboxymethyl cellulose, polyacrylamide and a defoaming agent to obtain slurry II, and mixing the slurry II with polyisocyanate to obtain the phase change heat storage external coating. Spraying the high-thermal-conductivity internal coating on the surface of the new energy battery, and curing to obtain a cured high-thermal-conductivity internal coating; and spraying the phase change heat storage outer coating on the surface of the cured high-heat-conductivity inner coating, and curing to obtain the composite phase change heat storage coating for the new energy battery. The prepared product is large in heat storage density, high in heat conductivity and good in cycling stability.

Description

Technical Field

[0001] The present invention belongs to the technical field of composite phase-change thermal storage coatings, and specifically relates to a composite phase-change thermal storage coating for new energy batteries and a preparation method thereof. Background Art

[0002] In recent years, the development and research of new energy vehicles has become a hot area of ​​global concern. As the key power source for new energy electric vehicles, the operating status of new energy batteries has a direct impact on the performance of the entire vehicle. New energy batteries include lithium cobalt oxide batteries, lithium iron phosphate batteries, nickel metal hydride batteries, ternary lithium batteries and graphene batteries. As the demand for energy and power of new energy batteries continues to grow, the performance degradation and safety hazards caused by heat accumulation during charging and discharging are becoming increasingly prominent. Temperature control of new energy batteries in high or low temperature environments has become a key factor in ensuring their performance and safety. Generally, the operating temperature of new energy batteries should be controlled within the range of 20°C to 45°C, and the temperature difference within the single battery should be kept within 10°C.

[0003] Currently, common cooling methods for new energy batteries include air cooling, liquid cooling, heat pipe cooling, and phase change material cooling. Phase change material cooling technology utilizes its characteristic of absorbing or releasing heat energy during phase change without changing temperature. Therefore, by forming a phase change thermal storage coating on the surface of new energy batteries, it can avoid excessively high or low operating temperatures of new energy batteries and improve temperature unevenness. This has attracted the attention of technicians in this field: The patented technology "A method for preparing a composite phase change coating that is beneficial to heat dissipation of lithium-ion batteries (CN201910987981.6)" uses paraffin as a phase change medium and attapulgite as an adsorption matrix to prepare a composite heat storage coating and apply it to the surface of a lithium battery. Although it can effectively reduce the internal temperature of the battery, the prepared phase change coating has a low thermal conductivity, which affects the heat exchange efficiency during actual application.

[0004] The patented technology "A coating with thermal regulation function and its lithium battery (CN202410491677.3)" uses a combination of a thermally conductive skeleton and a phase-change thermal storage material to coat the battery surface to control the heat of the battery. However, unpackaged phase-change thermal storage materials may leak during the cycle, resulting in poor cycle stability.

[0005] In the patented technology of "A battery cover and preparation method based on phase change microcapsule material, and electronic device (CN202411180567.1)", the technology disperses phase change microcapsules in the matrix resin to prepare a phase change thermal storage coating, which has good heat transfer and stability properties. However, the proportion of paraffin phase change medium is small, resulting in the prepared thermal storage coating having a low thermal storage density.

[0006] In the patented technology of "Power Battery, Coating Preparation Method and Vehicle (CN202110269921.8)", this technology uses phase change heat storage coating to slow down the temperature rise and heat accumulation of the power battery. However, it is difficult to achieve rapid heat transfer between the phase change coating and the battery by relying on thermal conductive adhesive, and the prepared phase change coating has the problem of low thermal conductivity.

[0007] In summary, existing composite phase change thermal storage coatings have the following technical defects: low thermal storage density, low thermal conductivity and poor cycle stability. Summary of the Invention

[0008] The present invention aims to overcome the defects of the prior art and has the purpose of providing a method for preparing a composite phase-change thermal storage coating for new energy batteries. The composite phase-change thermal storage coating for new energy batteries prepared by this method has high thermal storage density, high thermal conductivity and good cycle stability.

[0009] To achieve the above-mentioned purpose, the specific steps of the technical solution adopted by the present invention are: step 1, 30~40wt% of silicon carbide, 20~30wt% of diamond, 20~40wt% of aluminum sol, 2~6wt% of sodium carboxymethyl cellulose, 3~5wt% of polyacrylamide and 1~3wt% of defoaming agent are mixed to obtain slurry I; the mass ratio of slurry I to polyisocyanate is 1:0.05~0.10, the slurry I is mixed with the polyisocyanate, and the mixture is stirred evenly to obtain a high thermal conductive inner coating.

[0010] Step 2: Stir 40-60wt% of sodium sulfate decahydrate, 20-30wt% of n-eicosane and 20-30wt% of diatomaceous earth at 50-70°C for 1-3h, take out and cool to room temperature to obtain phase change microcapsules; mix the 50-70wt% phase change microcapsules, 20-40wt% of aluminum sol, 2-6wt% of sodium carboxymethyl cellulose, 3-5wt% of polyacrylamide and 1-3wt% of defoaming agent to obtain slurry II, and then mix the slurry II with the polyisocyanate at a mass ratio of slurry II: polyisocyanate of 1:0.05-0.10, stir evenly, and prepare a phase change thermal storage outer coating.

[0011] Step 3: Spray the high thermal conductivity inner coating prepared in step 1 on the surface of the new energy battery with ultrasonic atomization to a thickness of 40~60μm, and cure it for 1~2h to obtain a cured high thermal conductivity inner coating; then spray the phase change thermal storage outer coating prepared in step 2 on the surface of the cured high thermal conductivity inner coating with ultrasonic atomization to a thickness of 80~120μm, and then cure it for 1~2h to obtain a composite phase change thermal storage coating for new energy batteries.

[0012] The SiC content of the silicon carbide is ≥99.0wt%; and the particle size of the silicon carbide is ≤20μm.

[0013] The C content of the diamond is ≥99.0wt%; and the particle size of the diamond is ≤20μm.

[0014] The Al2O3 content of the aluminum sol in step 1 is ≥20.0wt%, the pH is 2-3, and the particle size of the aluminum sol is 10-25nm; the aluminum sol in step 2 is the same as the aluminum sol in step 1.

[0015] The defoaming agent in step 1 is a silicone defoaming agent or a polyether defoaming agent; the defoaming agent in step 2 is the same as the defoaming agent in step 1.

[0016] The content of 1,4-cyclohexanedimethyl diisocyanate in the polyisocyanate in step 1 is ≥75.0 mol%; the polyisocyanate in step 2 is the same as the polyisocyanate in step 1.

[0017] The sodium sulfate decahydrate has a Na2SO4·10H2O content of ≥99.0 wt%.

[0018] The C of n-eicosane 20 H 42 Content ≥99.0wt%.

[0019] The SiO2 content in the diatomaceous earth is ≥80.0wt%, and the Al2O3 content is ≥3.0wt%; the particle size of the diatomaceous earth is ≤25μm.

[0020] Due to the adoption of the above technical solution, the present invention has the following positive effects compared with the prior art: (1) The present invention uses sodium sulfate decahydrate as an inorganic phase change medium and n-eicosane as an organic phase change medium and stabilizer, and utilizes the characteristics of high phase change latent heat and suitable phase change temperature of the two to absorb heat when the battery temperature rises and release heat when the temperature drops, thereby achieving effective regulation of the battery temperature. Therefore, the prepared composite phase change thermal storage coating for new energy batteries has a high thermal storage density.

[0021] (2) The present invention introduces silicon carbide and diamond as the main components of the inner coating, and utilizes the high thermal conductivity of silicon carbide and diamond to achieve rapid heat transfer between new energy batteries and phase change thermal storage coatings, greatly reducing the overheating and overcooling problems of new energy batteries. Therefore, the prepared composite phase change thermal storage coating for new energy batteries has high thermal conductivity.

[0022] (3) The present invention makes full use of the complex pore structure and large specific surface area of ​​diatomaceous earth to improve the adsorption capacity of sodium sulfate decahydrate and n-eicosane, effectively stabilizing their phase change process. Therefore, the prepared composite phase change thermal storage coating for new energy batteries has good cycle stability.

[0023] The composite phase-change thermal storage coating for new energy batteries prepared by the present invention has been tested: the phase change latent heat is 120-160 J / g; the thermal conductivity is 20-25 W / (m·K); there is no obvious expansion during the phase change process of the composite phase-change thermal storage coating after spraying; the temperature difference between the inside and outside of the battery during 4C rate discharge is 4-7°C; and the 1000-cycle capacity retention rate is 93.0-94.5%.

[0024] The testing standards for the performance indicators involved in the present invention are: the latent heat of phase change is measured according to GB / T 19466.3-2004; and the thermal conductivity is measured according to ASTM-E1461.

[0025] Therefore, the composite phase-change thermal storage coating for new energy batteries prepared by the present invention has the characteristics of high thermal storage density, high thermal conductivity and good cycle stability. DETAILED DESCRIPTION

[0026] The present invention will be further described below in conjunction with specific embodiments, which does not limit the scope of protection thereof.

[0027] A composite phase-change thermal storage coating for new energy batteries and its preparation method. The steps of the preparation method described in this specific embodiment are: Step 1: 30-40 wt% of silicon carbide, 20-30 wt% of diamond, 20-40 wt% of aluminum sol, 2-6 wt% of sodium carboxymethyl cellulose, 3-5 wt% of polyacrylamide and 1-3 wt% of defoaming agent are mixed to obtain slurry I; slurry I is mixed with polyisocyanate at a mass ratio of slurry I to polyisocyanate of 1:0.05-0.10, and stirred evenly to obtain a high thermal conductive inner coating.

[0028] Step 2: Stir 40-60wt% of sodium sulfate decahydrate, 20-30wt% of n-eicosane and 20-30wt% of diatomaceous earth at 50-70°C for 1-3h, take out and cool to room temperature to obtain phase change microcapsules; mix the 50-70wt% phase change microcapsules, 20-40wt% of aluminum sol, 2-6wt% of sodium carboxymethyl cellulose, 3-5wt% of polyacrylamide and 1-3wt% of defoaming agent to obtain slurry II, and then mix the slurry II with the polyisocyanate at a mass ratio of slurry II: polyisocyanate of 1:0.05-0.10, stir evenly, and prepare a phase change thermal storage outer coating.

[0029] Step 3: Spray the high thermal conductivity inner coating prepared in step 1 on the surface of the new energy battery with ultrasonic atomization to a thickness of 40~60μm, and cure it for 1~2h to obtain a cured high thermal conductivity inner coating; then spray the phase change thermal storage outer coating prepared in step 2 on the surface of the cured high thermal conductivity inner coating with ultrasonic atomization to a thickness of 80~120μm, and then cure it for 1~2h to obtain a composite phase change thermal storage coating for new energy batteries.

[0030] The Al2O3 content of the aluminum sol in step 1 is ≥20.0wt%, and the pH is 2-3.

[0031] The defoaming agent in step 1 is an organosilicon defoaming agent or a polyether defoaming agent.

[0032] The content of 1,4-cyclohexanedimethyl diisocyanate in the polyisocyanate in step 1 is ≥75.0 mol%.

[0033] The SiO2 content in the diatomaceous earth is ≥80.0wt%, and the Al2O3 content is ≥3.0wt%.

[0034] In this specific implementation mode: The SiC content of the silicon carbide is ≥99.0wt%; and the particle size of the silicon carbide is ≤20μm.

[0035] The C content of the diamond is ≥99.0wt%; and the particle size of the diamond is ≤20μm.

[0036] The colloidal particle size of the aluminum sol is 10 to 25 nm; the aluminum sol in step 2 is the same as the aluminum sol in step 1.

[0037] The defoaming agent in step 2 is the same as the defoaming agent in step 1.

[0038] The polyisocyanate in step 2 is the same as the polyisocyanate in step 1.

[0039] The sodium sulfate decahydrate has a Na2SO4·10H2O content of ≥99.0 wt%.

[0040] The C of n-eicosane 20 H 42 Content ≥99.0wt%.

[0041] The particle size of the diatomaceous earth is ≤25 μm.

[0042] Example 1 A composite phase-change thermal storage coating for new energy batteries and its preparation method. The steps of the preparation method described in this embodiment are: Step 1: 40 wt% of silicon carbide, 30 wt% of diamond, 20 wt% of aluminum sol, 6 wt% of sodium carboxymethyl cellulose, 3 wt% of polyacrylamide and 1 wt% of defoaming agent are mixed to obtain slurry I; slurry I is mixed with polyisocyanate at a mass ratio of slurry I to polyisocyanate of 1:0.05, and stirred evenly to obtain a high thermal conductive inner coating.

[0043] Step 2: Stir 40wt% of sodium sulfate decahydrate, 30wt% of n-eicosane and 30wt% of diatomaceous earth at 50°C for 1h, take out and cool to room temperature to obtain phase change microcapsules; mix the 50wt% phase change microcapsules, 40wt% of aluminum sol, 6wt% of sodium carboxymethyl cellulose, 3wt% of polyacrylamide and 1wt% of defoaming agent to obtain slurry II, and then mix slurry II with polyisocyanate at a mass ratio of slurry II: polyisocyanate of 1:0.05, stir evenly, and prepare a phase change thermal storage outer coating.

[0044] Step 3: Spray the high thermal conductivity inner coating prepared in step 1 on the surface of the new energy battery with ultrasonic atomization to a thickness of 40 μm, and cure it for 1 hour to obtain a cured high thermal conductivity inner coating; then spray the phase change thermal storage outer coating prepared in step 2 on the surface of the cured high thermal conductivity inner coating with ultrasonic atomization to a thickness of 80 μm, and then cure it for 1 hour to obtain a composite phase change thermal storage coating for new energy batteries.

[0045] The Al2O3 content of the aluminum sol in step 1 is 20.0wt% and the pH is 2.0.

[0046] The defoaming agent in step 1 is an organosilicon defoaming agent.

[0047] The content of 1,4-cyclohexanedimethyl diisocyanate in the polyisocyanate in step 1 is 75.0 mol%.

[0048] The SiO2 content in the diatomaceous earth is 80.0 wt%, and the Al2O3 content is 3.0 wt%.

[0049] The composite phase change thermal storage coating for new energy batteries prepared in this embodiment was tested: the phase change latent heat was 120 J / g; the thermal conductivity was 25 W / (m·K); there was no obvious expansion during the phase change process of the composite phase change thermal storage coating after spraying; the temperature difference between the inside and outside of the battery during 4C rate discharge was 4°C; and the 1000-cycle capacity retention rate was 94.5%.

[0050] Example 2 A composite phase-change thermal storage coating for new energy batteries and its preparation method. The steps of the preparation method described in this embodiment are: Step 1: 36 wt% of silicon carbide, 28 wt% of diamond, 26 wt% of aluminum sol, 5 wt% of sodium carboxymethyl cellulose, 3 wt% of polyacrylamide and 2 wt% of defoaming agent are mixed to obtain slurry I; slurry I is mixed with polyisocyanate at a mass ratio of slurry I to polyisocyanate of 1:0.07, and stirred evenly to obtain a high thermal conductive inner coating.

[0051] Step 2: Stir 50wt% of sodium sulfate decahydrate, 25wt% of n-eicosane and 25wt% of diatomaceous earth at 60°C for 2h, take out and cool to room temperature to obtain phase change microcapsules; mix the 58wt% phase change microcapsules, 32wt% of aluminum sol, 5wt% of sodium carboxymethyl cellulose, 3wt% of polyacrylamide and 2wt% of defoaming agent to obtain slurry II, and then mix the slurry II with the polyisocyanate at a mass ratio of slurry II: polyisocyanate of 1:0.07, stir evenly, and prepare a phase change thermal storage outer coating.

[0052] Step 3: Spray the high thermal conductivity inner coating prepared in step 1 on the surface of the new energy battery with ultrasonic atomization to a thickness of 50 μm, and cure it for 1.5 hours to obtain a cured high thermal conductivity inner coating; then spray the phase change thermal storage outer coating prepared in step 2 on the surface of the cured high thermal conductivity inner coating with ultrasonic atomization to a thickness of 90 μm, and then cure it for 1.5 hours to obtain a composite phase change thermal storage coating for new energy batteries.

[0053] The Al2O3 content of the aluminum sol in step 1 is ≥20.9wt%, and the pH is 2.4.

[0054] The defoaming agent in step 1 is an organosilicon defoaming agent.

[0055] The content of 1,4-cyclohexanedimethyl diisocyanate in the polyisocyanate in step 1 is 77.2 mol%.

[0056] The SiO2 content in the diatomaceous earth is 80.6wt%, and the Al2O3 content is 3.4wt%.

[0057] The composite phase-change thermal storage coating for new energy batteries prepared in this embodiment was tested to have the following characteristics: the latent heat of phase change was 132 J / g; the thermal conductivity was 23 W / (m·K); there was no obvious expansion during the phase change process of the composite phase-change thermal storage coating after spraying; the temperature difference between the inside and outside of the battery during 4C rate discharge was 5°C; and the capacity retention rate after 1000 cycles was 94.1%.

[0058] Example 3 A composite phase-change thermal storage coating for new energy batteries and its preparation method. The steps of the preparation method described in this embodiment are: Step 1: 34 wt% of silicon carbide, 24 wt% of diamond, 32 wt% of aluminum sol, 4 wt% of sodium carboxymethyl cellulose, 4 wt% of polyacrylamide and 2 wt% of defoaming agent are mixed to obtain slurry I; slurry I is mixed with polyisocyanate at a mass ratio of slurry I to polyisocyanate of 1:0.09, and stirred evenly to obtain a high thermal conductive inner coating.

[0059] Step 2: Stir 55wt% of sodium sulfate decahydrate, 22wt% of n-eicosane and 23wt% of diatomaceous earth at 65°C for 2h, take out and cool to room temperature to obtain phase change microcapsules; mix the 65wt% phase change microcapsules, 25wt% of aluminum sol, 4wt% of sodium carboxymethyl cellulose, 4wt% of polyacrylamide and 2wt% of defoaming agent to obtain slurry II, and then mix slurry II with polyisocyanate at a mass ratio of slurry II: polyisocyanate of 1:0.09, stir evenly, and prepare a phase change thermal storage outer coating.

[0060] Step 3: Spray the high thermal conductivity inner coating prepared in step 1 on the surface of the new energy battery with ultrasonic atomization to a thickness of 55 μm, and cure it for 1.5 hours to obtain a cured high thermal conductivity inner coating; then spray the phase change thermal storage outer coating prepared in step 2 on the surface of the cured high thermal conductivity inner coating with ultrasonic atomization to a thickness of 100 μm, and then cure it for 1.5 hours to obtain a composite phase change thermal storage coating for new energy batteries.

[0061] The Al2O3 content of the aluminum sol in step 1 is 21.5wt% and the pH is 2.8.

[0062] The defoaming agent in step 1 is a polyether defoaming agent.

[0063] The content of 1,4-cyclohexanedimethyl diisocyanate in the polyisocyanate in step 1 is 78.9 mol%.

[0064] The SiO2 content in the diatomaceous earth is 81.7wt%, and the Al2O3 content is 3.7wt%.

[0065] The composite phase-change thermal storage coating for new energy batteries prepared in this embodiment was tested to have the following characteristics: the latent heat of phase change was 153 J / g; the thermal conductivity was 22 W / (m·K); there was no obvious expansion during the phase change process of the composite phase-change thermal storage coating after spraying; the temperature difference between the inside and outside of the battery during 4C rate discharge was 6°C; and the capacity retention rate after 1000 cycles was 93.4%.

[0066] Example 4 A composite phase-change thermal storage coating for new energy batteries and its preparation method. The steps of the preparation method described in this embodiment are: Step 1: 30 wt% of silicon carbide, 20 wt% of diamond, 40 wt% of aluminum sol, 2 wt% of sodium carboxymethyl cellulose, 5 wt% of polyacrylamide and 3 wt% of defoaming agent are mixed to obtain slurry I; slurry I is mixed with polyisocyanate at a mass ratio of slurry I to polyisocyanate of 1:0.10, and stirred evenly to obtain a high thermal conductive inner coating.

[0067] Step 2: Stir 60wt% of sodium sulfate decahydrate, 20wt% of n-eicosane and 20wt% of diatomaceous earth at 70°C for 3h, take out and cool to room temperature to obtain phase change microcapsules; mix the 70wt% phase change microcapsules, 20wt% of aluminum sol, 2wt% of sodium carboxymethyl cellulose, 5wt% of polyacrylamide and 3wt% of defoaming agent to obtain slurry II, and then mix slurry II with polyisocyanate at a mass ratio of slurry II: polyisocyanate of 1:0.10, stir evenly, and prepare a phase change thermal storage outer coating.

[0068] Step 3: Spray the high thermal conductivity inner coating prepared in step 1 on the surface of the new energy battery with ultrasonic atomization to a thickness of 60 μm, and cure it for 2 hours to obtain a cured high thermal conductivity inner coating; then spray the phase change thermal storage outer coating prepared in step 2 on the surface of the cured high thermal conductivity inner coating with ultrasonic atomization to a thickness of 120 μm, and then cure it for 2 hours to obtain a composite phase change thermal storage coating for new energy batteries.

[0069] The Al2O3 content of the aluminum sol in step 1 is 22.0wt% and the pH is 3.0.

[0070] The defoaming agent in step 1 is a polyether defoaming agent.

[0071] The content of 1,4-cyclohexanedimethyl diisocyanate in the polyisocyanate in step 1 is 80.0 mol%.

[0072] The SiO2 content in the diatomaceous earth is 82.1 wt%, and the Al2O3 content is 4.0 wt%.

[0073] The composite phase change thermal storage coating for new energy batteries prepared in this embodiment was tested: the phase change latent heat was 160 J / g; the thermal conductivity was 20 W / (m·K); there was no obvious expansion during the phase change process of the composite phase change thermal storage coating after spraying; the temperature difference between the inside and outside of the battery during 4C rate discharge was 7°C; and the 1000-cycle capacity retention rate was 93.0%.

[0074] Compared with the prior art, this embodiment has the following positive effects: (1) This specific embodiment uses sodium sulfate decahydrate as an inorganic phase change medium and n-eicosane as an organic phase change medium and stabilizer, and utilizes the characteristics of high phase change latent heat and suitable phase change temperature of the two to absorb heat when the battery temperature rises and release heat when the temperature drops, thereby achieving effective regulation of the battery temperature. Therefore, the prepared composite phase change thermal storage coating for new energy batteries has a high thermal storage density.

[0075] (2) This specific embodiment introduces silicon carbide and diamond as the main components of the inner coating, and utilizes the high thermal conductivity of silicon carbide and diamond to achieve rapid heat transfer between the new energy battery and the phase change thermal storage coating, greatly reducing the overheating and overcooling problems of the new energy battery. Therefore, the prepared composite phase change thermal storage coating for new energy batteries has high thermal conductivity.

[0076] (3) This specific embodiment makes full use of the complex pore structure and large specific surface area of ​​diatomaceous earth to improve the adsorption capacity of sodium sulfate decahydrate and n-eicosane, effectively stabilize their phase change process, and thus the prepared composite phase change thermal storage coating for new energy batteries has good cycle stability.

[0077] The composite phase-change thermal storage coating for new energy batteries prepared according to this specific embodiment has been tested: the phase change latent heat is 120~160J / g; the thermal conductivity is 20~25W / (m·K); there is no obvious expansion during the phase change process of the composite phase-change thermal storage coating after spraying; the temperature difference between the inside and outside of the battery at a 4C rate discharge is 4~7°C; and the 1000-cycle capacity retention rate is 93.0~94.5%.

[0078] The testing standards for the performance indicators involved in this specific embodiment are: the latent heat of phase change is measured according to GB / T 19466.3-2004; and the thermal conductivity is measured according to ASTM-E1461.

[0079] Therefore, the composite phase-change thermal storage coating for new energy batteries prepared in this specific embodiment has the characteristics of high thermal storage density, high thermal conductivity and good cycle stability.

Claims

1. A method for preparing a composite phase-change thermal storage coating for new energy batteries, characterized in that: The preparation method is: Step 1: 30-40 wt% of silicon carbide, 20-30 wt% of diamond, 20-40 wt% of aluminum sol, 2-6 wt% of sodium carboxymethyl cellulose, 3-5 wt% of polyacrylamide and 1-3 wt% of a defoaming agent are mixed to obtain slurry I; The slurry I and the polyisocyanate are mixed at a mass ratio of slurry I to polyisocyanate of 1:0.05-0.10, and stirred evenly to prepare a high thermal conductive inner coating; Step 2: 40-60wt% of sodium sulfate decahydrate, 20-30wt% of n-eicosane and 20-30wt% of diatomaceous earth are stirred at 50-70°C for 1-3h, taken out and cooled to room temperature to obtain phase change microcapsules; 50-70wt% of the phase change microcapsules, 20-40wt% of aluminum sol, 2-6wt% of sodium carboxymethyl cellulose, 3-5wt% of polyacrylamide and 1-3wt% of a defoaming agent are mixed to obtain slurry II, and then the slurry II is mixed with the polyisocyanate at a mass ratio of slurry II: polyisocyanate of 1:0.05-0.10, and stirred evenly to obtain a phase change thermal storage outer coating; Step 3: Spray the high thermal conductivity inner coating prepared in step 1 on the surface of the new energy battery with ultrasonic atomization to a thickness of 40~60μm, and cure it for 1~2h to obtain a cured high thermal conductivity inner coating; then spray the phase change thermal storage outer coating prepared in step 2 on the surface of the cured high thermal conductivity inner coating with ultrasonic atomization to a thickness of 80~120μm, and then cure it for 1~2h to obtain a composite phase change thermal storage coating for new energy batteries.

2. The method for preparing a composite phase-change thermal storage coating for new energy batteries according to claim 1, characterized in that: The SiC content of the silicon carbide is ≥99.0wt%; and the particle size of the silicon carbide is ≤20μm.

3. The method for preparing a composite phase-change thermal storage coating for new energy batteries according to claim 1, characterized in that: The C content of the diamond is ≥99.0wt%; and the particle size of the diamond is ≤20μm.

4. The method for preparing a composite phase-change thermal storage coating for new energy batteries according to claim 1, characterized in that: The Al2O3 content of the aluminum sol in step 1 is ≥20.0wt%, the pH is 2-3, and the particle size of the aluminum sol is 10-25nm; the aluminum sol in step 2 is the same as the aluminum sol in step 1.

5. The method for preparing a composite phase-change thermal storage coating for new energy batteries according to claim 1, characterized in that: The defoaming agent in step 1 is a silicone defoaming agent or a polyether defoaming agent; the defoaming agent in step 2 is the same as the defoaming agent in step 1.

6. The method for preparing a composite phase-change thermal storage coating for new energy batteries according to claim 1, characterized in that: The content of 1,4-cyclohexanedimethyl diisocyanate in the polyisocyanate in step 1 is ≥75.0 mol%; the polyisocyanate in step 2 is the same as the polyisocyanate in step 1.

7. The method for preparing a composite phase-change thermal storage coating for new energy batteries according to claim 1, characterized in that: The sodium sulfate decahydrate has a Na2SO4·10H2O content of ≥99.0 wt%.

8. The method for preparing a composite phase-change thermal storage coating for new energy batteries according to claim 1, characterized in that: The C of n-eicosane 20 H 42 Content ≥99.0wt%.

9. The method for preparing a composite phase-change thermal storage coating for new energy batteries according to claim 1, characterized in that: The SiO2 content in the diatomaceous earth is ≥80.0wt%, and the Al2O3 content is ≥3.0wt%; the particle size of the diatomaceous earth is ≤25μm.

10. A composite phase change thermal storage coating for new energy batteries, characterized by: The composite phase-change thermal storage coating for new energy batteries is a composite phase-change thermal storage coating for new energy batteries prepared according to the preparation method of the composite phase-change thermal storage coating for new energy batteries according to any one of claims 1 to 9.