Composite coating for protecting new energy power battery liquid cooling plate and preparation method thereof

Abstract

The application discloses a composite coating for protecting a liquid cooling plate of a new energy power battery and a preparation method thereof, and contains the following raw materials in parts by weight: modified MXene / graphene double carriers 70-90 parts, core-shell structure Cu@ZIF-8@double carrier powder 5-12 parts, alkali-soluble acrylic copolymer resin 15-25 parts, KH-570 0.5-1.5 parts, fluorocarbon surfactant L30 0.2-0.8 parts, zinc phosphate 8-12 parts, mica powder 8-12 parts, polyamide wax 12-18 parts, K-7318 2-4 parts, and diatomite 12-18 parts; wherein the core-shell structure Cu@ZIF-8@double carrier powder is a core-shell structure formed by in-situ growth of Cu@ZIF-8 on an MXene / graphene interface. The application provides a comprehensive protective layer with super-hydrophobicity, corrosion resistance, antibacterial property and high adhesion for the liquid cooling plate, and has excellent performance.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of protection of key components of new energy power battery thermal management systems, and in particular to a composite coating for protecting a new energy power battery liquid cooling plate and a preparation method thereof. BACKGROUND

[0002] With the rapid development of new energy electric vehicles, the thermal management safety of power batteries is crucial. As the core component of the battery thermal management system, the liquid cooling plate is directly in contact with the coolant for a long time, facing the challenges of electrochemical corrosion, ion penetration, and microbial growth (especially in ethylene glycol-water type coolant). These factors can cause corrosion perforation of the liquid cooling plate, coolant leakage, thermal management failure, and even safety accidents such as battery system short circuit.

[0003] Traditional protective coatings for liquid cooling plates (such as conventional epoxy coatings or passivation films) often have single functions and are difficult to meet the requirements of long-term corrosion prevention, microbial inhibition, and resistance to long-term immersion and cold-heat cycling of the coolant. New nanomaterials such as graphene or MXene can improve corrosion resistance, but their dispersion in the coating, adhesion to the substrate, and functional synergy are still technical difficulties. In particular, microbial contamination in the coolant environment can form a biofilm, reducing heat exchange efficiency and exacerbating local corrosion, and existing technologies lack effective active antibacterial mechanisms.

[0004] Therefore, the development of a multifunctional composite coating that can firmly adhere to the liquid cooling plate substrate (usually aluminum alloy or stainless steel) and synergistically provide physical barrier, chemical corrosion prevention, active antibacterial, and surface hydrophobicity (to prevent the adhesion of harmful substances in the coolant) is of great significance to improve the reliability, safety, and service life of the power battery system. SUMMARY

[0005] The purpose of the present application is to provide a composite coating for protecting a new energy power battery liquid cooling plate and a preparation method thereof. The coating solves the defects of traditional functional coatings in which antibacterial, hydrophobic, and corrosion resistance are difficult to be considered simultaneously due to poor material interface compatibility and uneven dispersion of functional phases by constructing a "double two-dimensional carrier-core shell synergistic" system. The ZIF-8 crystal nucleus is anchored by the surface -F / -OH functional group of MXene (Ti3C2T x ), and the graphene sheet provides an extension plane. The two are cross-linked by a silane coupling agent to form a three-dimensional conductive network to inhibit stacking. Cu@ZIF-8 is in-situ grown on the MXene / graphene interface to form a "core-shell double barrier" structure (Cu@ZIF-8 as the core and double two-dimensional materials as the shell), which prolongs the diffusion path of the corrosion medium by more than 3.2 times. The double carrier improves the Cu 2+ / Zn 2+ release stability, inhibits ion burst release, and synergizes with the antibacterial activity of MXene (F -The graphene physically blocks the cell membrane destruction, achieves a bacteriostatic rate of 99% and a salt spray corrosion resistance of 1000h. The coating significantly improves the comprehensive protection performance of the coating, especially the antibacterial property, surface hydrophobicity (water contact angle > 150°), corrosion resistance and adhesion (≥13MPa, not more than 1 level), and can be widely applied to the liquid cooling plate of the power battery pack of the electric vehicle, the liquid cooling system of the battery cluster of the energy storage power station, the liquid cooling system matched with the high-power charging facility and other harsh protection performance required fields.

[0006] To achieve the above object, the present application provides the following technical scheme:

[0007] A composite coating for protecting a new energy power battery liquid cooling plate, comprising the following raw materials by weight:

[0008] Modified MXene / graphene double carrier: 70-90 parts,

[0009] Core-shell structure Cu@ZIF-8@double carrier powder: 5-12 parts,

[0010] Alkali-soluble acrylic copolymer resin: 15-25 parts,

[0011] Silane coupling agent KH-570: 0.5-1.5 parts,

[0012] Fluorocarbon surfactant L30: 0.2-0.8 parts,

[0013] Zinc phosphate: 8-12 parts,

[0014] Mica powder: 8-12 parts,

[0015] Polyamide wax: 12-18 parts,

[0016] Curing accelerator K-7318: 2-4 parts,

[0017] Diatomite: 12-18 parts;

[0018] The core-shell structure Cu@ZIF-8@double carrier powder is a core-shell structure formed by in-situ growth of Cu@ZIF-8 on the interface of MXene / graphene.

[0019] Cu@ZIF-8 is prepared by in-situ loading of copper ions (Cu 2+ ) in the ZIF-8 skeleton structure formed by coordination of zinc ions (Zn 2+ ) and 2-methyl imidazole.

[0020] Further, the preparation process of the modified MXene / graphene double carrier is: mixing MXene and reduced graphene oxide in a mass ratio of 0.8-1:1, then adding silane coupling agent KH-570, and reacting at 55-60°C for 2-3h to form a cross-linked modified MXene / graphene double carrier, wherein the added mass of the silane coupling agent KH-570 is 1 / 4-1 / 3 of the total mass of MXene and reduced graphene oxide.

[0021] Further, the core-shell structure Cu@ZIF-8@double carrier powder is prepared from the modified MXene / graphene double carrier, and the specific preparation process is:

[0022] The modified MXene / graphene double carrier is configured into a double carrier methanol dispersion liquid, and then Zn(NO3)2·6H2O and Cu(NO3)2·3H2O are added and magnetically stirred at 40°C for 30min.

[0023] A methanol solution containing 2-methylimidazole is added dropwise, and stirring is performed at 60°C for 4h to complete in-situ crystallization of ZIF-8 through heterogeneous nucleation on the surface of the carrier.

[0024] The total mass of zinc nitrate hexahydrate and copper nitrate trihydrate and the volume of total methanol are in a ratio of (0.3-0.6)g:40mL, the mass of 2-methylimidazole and the volume of total methanol are in a ratio of (0.3-0.7)g:40mL, and the mass of the modified MXene / graphene double carrier and the volume of total methanol are in a ratio of (0.4-0.6)g:40mL.

[0025] After in-situ crystallization, centrifugation is performed at a rotation speed of 8000-12000rpm, methanol washing is performed for 3-5 times, vacuum drying is performed at a drying temperature of 50-70°C for 6-10h, and the core-shell structure Cu@ZIF-8@double carrier powder is obtained, which is a light blue core-shell powder.

[0026] Further, the composite coating is tested, and the cross-hatch adhesion grade is ≤1, the pull-off strength is ≥13.5MPa, the antibacterial rate is not less than 99.0%, the water contact angle is >150°, and the salt spray corrosion resistance is not less than 800h; preferably, the antibacterial rate is not less than 99.3%, and the salt spray corrosion resistance is not less than 1000h.

[0027] Further, the mass ratio of the modified MXene / graphene double carrier and the core-shell structure Cu@ZIF-8@double carrier powder is 100:(10-15).

[0028] Further, the mass ratio of zinc nitrate hexahydrate and copper nitrate trihydrate is (10-16):2.

[0029] The preparation method of the above composite coating is as follows:

[0030] a. Ball milling diatomite to 20~25 μm to obtain pretreated diatomite;

[0031] b. Mixing modified MXene / graphene double carrier, alkali-soluble acrylic copolymer resin and deionized water, adding zinc phosphate and pretreated diatomite;

[0032] c. After stirring at 85±5℃ for 50~60 min, removing impurities by centrifugation at a speed of 3500~3600 rpm;

[0033] d. Adding mica powder and curing accelerator into the centrifuged filtrate in sequence and mixing uniformly, then adding polyamide wax, KH-570 and L30, stirring uniformly at 85±5℃, and then performing high-temperature curing treatment to obtain a modified dispersion liquid;

[0034] e. Adding core-shell structure Cu@ZIF-8@double carrier powder into the modified dispersion liquid, and obtaining the composite coating for protecting new energy power battery liquid cooling plate after ultrasonic treatment at 50~65℃.

[0035] Further, during the spraying construction of the composite coating, ultrasonic assisted spraying is adopted to make the graphene sheet layer lay flat on the substrate surface.

[0036] Compared with the prior art, the present application has the following beneficial effects:

[0037] The present application has synergistic antibacterial property: the double carrier synergistic effect builds a high-efficiency functional platform: the -F / -OH functional groups on the surface of MXene precisely anchor the ZIF-8 crystal nucleus, significantly improving the loading rate (>90%) and preventing falling off; the graphene sheet layer provides an extension plane, and is crosslinked with MXene through a silane coupling agent to form a three-dimensional conductive network, completely inhibiting the stacking problem of two-dimensional materials. This unique structure makes Cu 2+ / Zn 2+ achieve synergistic slow release: MXene conductive network promotes uniform ion diffusion, graphene physical barrier prolongs the release period, and the double ion antibacterial efficiency breaks through 99.99% (more than 7% higher than the physical mixing system), and the antibacterial spectrum and long-acting property far exceed traditional technology.

[0038] The application has excellent corrosion resistance, and the “core-shell double barrier” structure (Cu@ZIF-8 as the core and double two-dimensional materials as the shell) forms a triple protection mechanism: the MXene / graphene crosslinked network constructs a dense “double two-dimensional maze” in the coating, so that the diffusion path of the corrosion medium is lengthened by 3.2 times, and the actual measured salt spray corrosion resistance is >800 hours, preferably >1000 hours; the high conductivity of MXene accelerates electron transfer, cooperates with zinc phosphate to form a stable passivation film, and the ions released by Cu@ZIF-8 deposit protective oxides at defects; the silane coupling agent bridges the double carriers and the alkali-soluble acrylic copolymer resin, and the efficient filling (BET >1100 m 2 / g) of the core-shell structure to micropores reduces the porosity of the coating by more than 60%, completely blocking the penetration channel.

[0039] The prepared coating has high adhesion: zinc phosphate reacts with the surface of the metal substrate to form a firm chemical bond. The silane coupling agent KH-570 can improve the compatibility and interfacial bonding force of inorganic fillers (graphene, mica, diatomite) and organic resins (alkali-soluble acrylic copolymer resin). The dense and well-bonded coating structure together ensures that the coating has excellent adhesion (0-1 level), realizes better interfacial performance at a lower cost, and has excellent comprehensive performance.

[0040] The coating of the application builds the core-shell structure Cu@ZIF-8@double carrier powder, aiming to provide a comprehensive protective layer with super-hydrophobicity, corrosion resistance, antibacterial property and high adhesion for the liquid cooling plate. The double carrier adopts a double two-dimensional carrier composed of MXene / graphene, which has excellent performance. DETAILED DESCRIPTION

[0041] The technical solutions of the application will be described in detail below with reference to the embodiments. Obviously, the described embodiments are only some of the embodiments of the application, not all the embodiments. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the application.

[0042] It should be noted that the embodiments described below or the technical features thereof can be combined in any manner to form new embodiments without conflict.

[0043] In order to make the purpose, technical solutions and advantages of the application more clear, the application will be further described in detail below with reference to the embodiments. It should be understood that the following description is only used to explain the application, and does not limit the application.

[0044] The various reagents used in the following examples and comparative examples are all ordinary commercially available products.

[0045] Example 1: Preparation of modified MXene / graphene double carrier

[0046] 1.0 g of Ti3AlC2 was added to 20 mL of 40%wt HF, and stirred magnetically at 35°C for 24 h;

[0047] Centrifugal washing until pH>6, precipitate was added with 0.5M TMAOH solution, ultrasonic at 20KHz for 1h (ultrasonic power was 300W), and dried to obtain exfoliated MXene.

[0048] 0.8 g of exfoliated MXene was mixed with 1.0 g of reduced graphene oxide (rGO), and 0.5 g of KH-570 was added;

[0049] Reaction at 60°C for 2h, to obtain modified MXene / graphene double carrier, and the Zeta potential was measured as +38mV.

[0050] Example 2: Preparation of core-shell structure Cu@ZIF-8@double carrier powder

[0051] The modified MXene / graphene double carrier of Example 1 was dispersed with ethanol or methanol (methanol dispersion was used in this example), configured into a double carrier dispersion liquid, 0.297 g of Zn(NO3)2·6H2O and 0.042 g of Cu(NO3)2·3H2O were added, and stirred magnetically at 40°C for 30 min.

[0052] 0.65 g of 2-methylimidazole was added dropwise in methanol solution (collectively referred to as 2-methylimidazole solution), and stirred at 60°C for 4h (non-ambient temperature), to complete the in-situ crystallization of ZIF-8; the total volume of all methanol was 40 mL; the mass of modified MXene / graphene double carrier was 0.5 g.

[0053] After in-situ crystallization, centrifugation was performed at a speed of 10000 rpm, washed with methanol for 3 times, and vacuum dried at 60°C for 8h, to obtain light blue core-shell powder (coating rate was 92%, BET was 1120m 2 / g), which was the core-shell structure Cu@ZIF-8@double carrier powder.

[0054] Example 3: Preparation of composite coating

[0055] A certain amount of diatomite was broken by ball milling (ball to material ratio was 5:1, 30 min), and the undersize part was taken through a 600 mesh screen, and sealed for standby use;

[0056] 80 parts of modified MXene / graphene double carrier (Example 1), 20 parts of alkali-soluble acrylic copolymer resin, 30 parts of deionized water were mixed, and then 10 parts of zinc phosphate, 15 parts of ball-milled diatomite were added, and stirred uniformly at a speed of 1000 rpm of anchor stirrer at room temperature;

[0057] Primary reaction: increase the temperature to 85℃ at a rate of 2℃ / min, stir for 50 min at 1000 rpm, use a viscometer to control the system viscosity ≤500 cP, monitor in real time;

[0058] Centrifugal purification: move the mixture into a high-temperature-resistant centrifuge tube, centrifuge at 25℃, 3500 r / min for 10 min; collect the supernatant after centrifugation, discard the >5 μm precipitate at the bottom, and achieve the purpose of removing impurities;

[0059] Functional addition: transfer the centrifuged filtrate (supernatant) into a blender, and sequentially add 10 parts of mica powder (previously dried at 105℃ for 2h) and 3 parts of curing accelerator K-7318, use a sawtooth dispersing disc, stir at 1200 rpm for 60 min, and mix uniformly;

[0060] Modification and reinforcement: slowly add 15 parts of polyamide wax 6900-20X, 1.0 parts of silane coupling agent KH-570, and 0.5 parts of fluorocarbon surfactant L30 to the system using a constant pressure dropping funnel to control the flow rate, increase the temperature to 85±5℃ at a rate of 1℃ / min, and stir at 800 rpm for 90 min, and mix uniformly;

[0061] High-temperature curing treatment: keep the temperature at 85±5℃ for 60 min, and then cool to 40℃ before discharging, to obtain a modified dispersion liquid;

[0062] Then add 5 parts of core-shell structure Cu@ZIF-8@double carrier powder (Example 2) to the modified dispersion liquid, and ultrasonically treat at 60℃ for 2h (ultrasonic power is 500W), to obtain the composite coating for new energy power battery liquid cooling plate protection, which is the MXene / graphene double two-dimensional carrier enhanced core-shell structure Cu@ZIF-8 composite coating.

[0063] Example 4: Preparation of a composite coating

[0064] The steps and raw materials of the composite coating of this example are the same as those of Example 3, except that the amount of core-shell structure Cu@ZIF-8@double carrier powder added is 10 parts.

[0065] Example 5: Preparation of a composite coating

[0066] The steps and raw materials of the composite coating of this example are the same as those of Example 3, except that the amount of core-shell structure Cu@ZIF-8@double carrier powder added is 12 parts.

[0067] Comparative Example 1:

[0068] Use 90 parts of ordinary water-based reduced graphene oxide to replace the double carrier, and add 10 parts of physically mixed Cu@ZIF-8 powder (non-core-shell structure), and the rest of the components and steps are the same as those of Example 4.

[0069] Comparative Example 2:

[0070] Use the double carrier of Example 1, but add 10 parts of physically mixed Cu@ZIF-8 powder, the rest is the same as Example 4.

[0071] Comparative Example 3:

[0072] Load Cu@ZIF-8 with MXene only (no graphene), the amount added is the same as Example 4, and the rest of the components are consistent.

[0073] Comparative Example 4:

[0074] Select a brand of epoxy anticorrosive paint (solid content 50%), follow the manufacturer's instructions for construction. Replace the Cu@ZIF-8 powder with 10 parts of physically mixed ZIF-8 powder and CuO nano powder (add the amount according to the molar ratio of Zn:Cu=4:1). The physically mixed powder is only mechanically mixed. Add 10 parts of mechanically mixed powder to the epoxy anticorrosive paint and ultrasonic treat at 60°C for 2h (ultrasonic power is 500W).

[0075] In order to test the related performance of the composite coating of the present application, the composite coating is sprayed onto the surface of a 1x1cm copper sheet with ultrasonic assistance. During the spraying process, ultrasonic vibration energy is applied to the workpiece being sprayed, causing the graphene flakes located in the viscous flow state coating to gradually stretch and lay flat on the surface of the workpiece. The coating thickness is 0.2μm. The test is simulated during the service process. Specifically, Examples 3-5 and Comparative Examples 1-4 are tested as follows, and the test results are shown in Table 1:

[0076] Corrosion resistance test: neutral salt spray test (NSS, GB / T10125-2021): inject a prepared sodium chloride solution with a mass fraction of (5±1)% into the salt spray test chamber, maintain the temperature in the test chamber at (35±2)℃, generate salt spray through a spraying device, and continuously spray the salt spray with a settling amount in the range of (1-2)mL / (80cm 2 •h). The test sample should be placed at a specified angle to ensure that the salt spray can uniformly settle on the surface of the sample. The test duration is determined according to the sample characteristics and test requirements. During the test, observe the corrosion of the sample, and after the test is completed, clean and inspect the sample to evaluate its corrosion resistance. Record the time (h) when red rust appears on the coating.

[0077] Antibacterial test: according to GB / T31402-2023, Determination of antibacterial activity on the surface of plastics and other non-porous materials[S]. Test the antibacterial performance of each coating.

[0078] Surface hydrophobicity: use OCA200 full-automatic single fiber contact angle measuring instrument to measure the static water contact angle (°) of the coating surface. Take the average value of 5 different points.

[0079] Adhesion test:

[0080] GB / T5210-2006, Paint and Varnish Pull-off Adhesion Test [S]. Record the pull-off strength (MPa) and failure type (A: cohesive failure, B: adhesive failure).

[0081] According to the grid method of ISO2409-2007, F107 grid marker is used to measure the adhesion of the coating. The edge of the notch is completely smooth, the grid edge has no peeling, the cross intersection of the notch has a small piece of peeling, the actual damage in the grid area is not more than 5% for level 1; the edge or intersection of the notch has peeling, the area is 5-15% for level 2; the edge or intersection of the notch has peeling, the area is 15-20% for level 3; the edge or intersection of the notch has peeling, the area is 20-25% for level 4; the edge of the notch has large peeling, the peeling area is 25-35% for level 5.

[0082] Table 1

[0083]

[0084] The composite coating of the present application exhibits breakthrough comprehensive protection performance. Through a triple synergistic mechanism, a technical breakthrough is achieved: first, the core-shell structure Cu@ZIF-8@double carrier realizes long-acting slow release of copper and zinc ions (bacteriostatic rate ≥ 99.3%), which significantly surpasses the physical mixing system (comparative examples 1-4, bacteriostatic rate ≤ 92.8%) in resisting escherichia coli and staphylococcus aureus, especially the bacteriostatic rates of example 4 on the two kinds of pathogenic bacteria are 99.9% and 99.7% respectively, verifying the synergistic effect of MOFs slow release and MXene / graphene antibacterial; second, the super-hydrophobic interface formed by the directional migration of silane coupling agent and fluorocarbon surfactant under the double carrier system (contact angle of example 4 is 155°±2°) effectively blocks the penetration of the medium, while the contact angle of comparative example 4 (ordinary composite, epoxy numerical solution) is only 105°±4°, and the single-loaded system without graphene (comparative example 3, contact angle is 92°±3°) confirms the synergistic hydrophobic mechanism of MXene-F group and graphene micro-nano roughness, and the migration of silane coupling agent KH-570 and fluorocarbon surfactant L30 to the surface during the curing process of the coating makes the water contact angle > 150° in the current system; third, the "brick and mud" maze structure formed by MXene / graphene, the nanopore filling of Cu@ZIF-8 and the chemical bonding of zinc phosphate in the multi-level corrosion protection barrier make the salt spray corrosion resistance of examples 3-4 break through 1000 hours, which is increased by 138% compared with the best comparative example (the salt spray corrosion resistance of comparative example 4 is 420 hours).

[0085] The key data comparison table shows that Example 4 (core-shell structure Cu@ZIF-8@double carrier powder addition amount 10%) is the optimal performance scheme: the antibacterial property reaches the peak value (99.9% E. coli inhibition rate), the hydrophobicity is the strongest (155°±2 contact angle), the corrosion resistance is flat with Example 3 and significantly better than Example 5 (salt spray 850 hours) due to the decrease in compactness caused by excessive addition, while maintaining the highest adhesion grade (14.8 MPa pull-off strength, 0 grade grid). This scheme perfectly balances functionality and stability, and compared with the commercial anticorrosive paint (Comparative Example 4), it achieves all-round breakthrough in corrosion resistance (>1000h vs 420h), inhibition rate (99.9% vs 88.3%) and adhesion (14.8 MPa vs 11.0 MPa), providing a revolutionary protection solution for electric vehicle power battery pack liquid cooling plates, energy storage power station battery cluster liquid cooling systems and other harsh environments.

[0086] The unmentioned part of the present application is applicable to the prior art.

Claims

1. A composite coating for the protection of liquid-cooled plates of new energy power batteries, characterized in that, The raw materials include the following parts by weight: Modified MXene / graphene dual carrier: 70 - 90 parts, Core - shell structured Cu@ZIF - 8@dual - carrier powder: 5 - 12 parts, Alkali - soluble acrylic copolymer resin: 15 - 25 parts, Silane coupling agent KH - 570: 0.5 - 1.5 parts, Fluorocarbon surfactant L30: 0.2 - 0.8 parts, Zinc phosphate: 8 - 12 parts, Mica powder: 8 - 12 parts, Polyamide wax: 12 - 18 parts, Curing accelerator K - 7318: 2 - 4 parts, Diatomite: 12 - 18 parts; Among them, the core - shell structured Cu@ZIF - 8@dual - carrier powder is a core - shell structure formed by the in - situ growth of Cu@ZIF - 8 on the MXene / graphene interface; The preparation process of the modified MXene / graphene dual carrier is as follows: Mix MXene and reduced graphene oxide at a mass ratio of 0.8~1:1, and then add silane coupling agent KH - 570. React at 55~60 °C for 2~3 h to form the modified MXene / graphene dual carrier. The added mass of the silane coupling agent KH - 570 is 1 / 4~1 / 3 of the total mass of MXene and reduced graphene oxide; The core - shell structured Cu@ZIF - 8@dual - carrier powder is prepared from the modified MXene / graphene dual carrier. The specific preparation process is as follows: Prepare a dual - carrier methanol dispersion of the modified MXene / graphene dual carrier. Take the dual - carrier methanol dispersion, add Zn(NO3)2·6H2O and Cu(NO3)2·3H2O, and stir magnetically at 40 °C for 30 min; Drop - wise add a methanol solution containing 2 - methylimidazole, stir at 60 °C for 4 h, and complete the in - situ crystallization of ZIF - 8 by heterogeneous nucleation on the surface of the carrier; Among them, the total mass ratio of zinc nitrate hexahydrate and copper nitrate trihydrate to the total volume of methanol is (0.3~0.6) g:40 mL, the mass ratio of 2 - methylimidazole to the total volume of methanol is (0.3~0.7) g:40 mL; the mass ratio of the modified MXene / graphene dual carrier to the total volume of methanol is (0.4~0.6) g:40 mL; After in - situ crystallization, centrifuge at a speed of 8000~12000 rpm, wash with methanol 3~5 times, and dry in vacuum. The drying temperature is 50 - 70 °C, and the drying time is 6 - 10 h to obtain the core - shell structured Cu@ZIF - 8@dual - carrier powder.

2. The composite coating for protecting liquid-cooled plates of new energy power batteries according to claim 1, characterized in that: The core-shell structured Cu@ZIF-8@dual-carrier powder exhibits a Cu@ZIF-8 coating rate >90% and a BET >1100 m. 2 / g.

3. The composite coating for protecting liquid-cooled plates of new energy power batteries according to claim 1, characterized in that: After testing, the cross - hatch adhesion grade of the composite coating ≤ 1 level, the pull - off strength ≥ 13.5 MPa, the antibacterial rate is not less than 99.0%, the water contact angle > 150°, and the salt spray corrosion resistance is not less than 800 h.

4. The composite coating for protecting liquid-cooled plates of new energy power batteries according to claim 1, characterized in that: The mass ratio of the modified MXene / graphene dual carrier to the core - shell structured Cu@ZIF - 8@dual - carrier powder is 100:(10~15).

5. The composite coating for protecting liquid-cooled plates of new energy power batteries according to any one of claims 1-4, characterized in that: The composite coating is used in the liquid - cooled plates of electric vehicle power battery packs, the liquid - cooled systems of battery clusters in energy storage power stations, and the liquid - cooled systems supporting high - power charging facilities.

6. A method for preparing a composite coating for the protection of liquid-cooled plates of new energy power batteries as described in claim 1, characterized in that: The process of the preparation method is as follows: [[ID= b. Mix the modified MXene / graphene dual carrier, alkali-soluble acrylic copolymer resin and deionized water, and add zinc phosphate and pretreated diatomaceous earth; c. Stir at 85±5℃ for 50~60 min, then centrifuge at 3500~3600 rpm to remove impurities; d. Add mica powder and curing accelerator to the filtrate after centrifugation and mix well. Then add polyamide wax, KH-570 and L30. Stir well at 85±5℃ and then perform high-temperature curing treatment to obtain modified dispersion. e. Add the core-shell structured Cu@ZIF-8@ dual-carrier powder to the modified dispersion, and then ultrasonically treat it at 50~65℃ to obtain the composite coating for the protection of the liquid cooling plate of the new energy power battery.

7. The preparation method according to claim 6, characterized in that: During the application of composite coatings, ultrasonic-assisted spraying is used to spread graphene sheets evenly on the substrate surface.

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