Water-based paint with co-insulativity and safety and carbon-coated current collector prepared from water-based paint

Abstract

The invention relates to the technical field of lithium batteries, in particular to water-based paint with co-insulativity and safety and a carbon-coated current collector prepared from the water-based paint. Comprising the following steps: step 1, mixing a dialuminum hydrogen phosphate binder with deionized water to obtain a glue solution; step 2, adding an insulating material into the glue solution in three times, dispersing at a high speed of 2000-2600 rpm / min for 30-60 minutes, adding deionized water, dispersing at a high speed for 30-60 minutes again, adding a pH regulator to regulate the pH to 6.9-7.1, adding a wetting agent, dispersing at a low speed of 10-15 rpm / min for 30-45 minutes, and homogenizing at a pressure of 550-650 bar for 2-3 times to obtain a water-based coating; and 3, coating the surface of the current collector with the water-based paint, and drying to form an insulating coating, thereby obtaining the carbon-coated current collector.

Description

Technical Field

[0001] This invention relates to the field of lithium battery technology, specifically to a water-based coating with both insulating and safe properties, and the carbon-coated current collector prepared therefrom. Background Art

[0002] Lithium-ion batteries, with their high energy density and long cycle life, have been widely used in new energy, electronics, power tools, and energy storage. In the lithium battery industry, to further improve the rate performance of lithium batteries, carbon-coated current collector technology is often used. This technology provides a static conductive network by coating a carbon layer on the surface of aluminum foil, reducing the contact resistance between the active material and the current collector and improving conductivity.

[0003] However, in practical applications, the edges of the carbon-coated current collector are prone to electrochemical corrosion and lithium plating due to long-term exposure to the electrolyte environment. This can lead to the formation of local conductive channels, resulting in leakage and significantly reducing the insulation and safety of the lithium battery.

[0004] To improve the safety of carbon-coated current collectors, existing technologies typically employ a ceramic edge-coating process. This involves applying ceramic slurry to the edges of the carbon-coated current collector to form an insulating protective barrier, thereby enhancing its safety. However, existing ceramic edge-coating processes present several problems in practical applications: Firstly, traditional adhesives often use organic resins, which are prone to decomposition and carbonization at high temperatures, leading to instability or even peeling of the carbon coating. Simultaneously, this releases large amounts of flammable gases, not only failing to suppress combustion but also indirectly providing fuel for combustion, significantly reducing the edge insulation and safety of the carbon-coated current collector. Secondly, the insulating material in insulating coatings typically uses single alumina ceramics. While this improves insulation, it is prone to crystal transformation at high temperatures, accompanied by volume shrinkage, which compromises the density of the ceramic layer, greatly reducing insulation performance and safety.

[0005] In summary, solving the above problems and preparing a water-based coating with both insulating and safe properties is of great significance. Summary of the Invention

[0006] The purpose of this invention is to provide a water-based coating with good insulation and safety, and a carbon-coated current collector prepared therefrom, to solve the problems mentioned in the background art.

[0007] To solve the above-mentioned technical problems, the present invention provides the following technical solution: A water-based coating with both insulating and safety properties, wherein the preparation method of the water-based coating is as follows: Step 1: Mix aluminum hydrogen phosphate binder with deionized water to obtain an adhesive solution; Step 2: Add the insulating material to the adhesive solution in three batches, disperse at high speed of 2000~2600 rpm / min for 30~60 min, add deionized water and disperse at high speed again for 30~60 min, add pH adjuster to adjust pH to 6.9~7.1, add wetting agent and disperse at low speed of 10~15 rpm / min for 30~45 min, then homogenize at a pressure of 550~650 bar 2~3 times to obtain water-based coating.

[0008] More preferably, the insulating material is an Al2O3-ZrO2 composite powder; the amount of Al2O3-ZrO2 composite powder added accounts for 50wt%~80wt% of the solid content in the water-based coating; the amount of wetting agent added accounts for 8wt%~12wt% of the total mass of the water-based coating.

[0009] In a more optimized manner, the preparation process of the aluminum hydrogen phosphate binder is as follows: a 20wt%~30wt% aqueous solution of phosphoric acid is heated to 60~80℃, followed by the addition of alumina, with a mass ratio of phosphoric acid to alumina of 2:0.9~1.1, and stirred at 80~90℃ for 1~2 hours. The pH is adjusted to 2.0~4.0 with ammonia water, and the mixture is concentrated to a solid content of 30~50% to obtain the aluminum hydrogen phosphate binder.

[0010] Ideally, the solid content of the adhesive solution is 30-50%; the viscosity of the adhesive solution is 800-3500 mPa·s.

[0011] In a more optimized manner, the preparation process of the Al2O3-ZrO2 composite powder is as follows: aluminum nitrate nonahydrate and zirconium oxychloride are added to deionized water at a mass ratio of 8:1.9~2.1, urea aqueous solution is added to adjust the pH to 9.0~10.0 to form a coprecipitate, and after washing and drying, it is calcined at 600~1000℃ for 2~4h to obtain Al2O3-ZrO2 composite powder.

[0012] In a further embodiment, the concentration of the urea aqueous solution is 0.8~1.2 mol / L.

[0013] More preferably, the pH adjuster is a 0.4~0.6 mmol / L sodium hydroxide aqueous solution; the amount of the pH adjuster added accounts for 5wt%~10wt% of the solid content in the water-based coating; the wetting agent includes one or more of polyether siloxane, modified polyether siloxane, and alcohol reagents.

[0014] In a more optimized manner, when the wetting agent is a modified polyether siloxane, the preparation process of the modified polyether siloxane is as follows: S1-1: Hydroxyethyl methacrylate and triethylamine are added to tetrahydrofuran, and hexachlorocyclotriphosphazene is added. The mixture is refluxed at 60-70°C for 20-28 hours, filtered, extracted, and dried. Subsequently, the mixture is added to tetrahydrofuran, and under a nitrogen atmosphere, mercaptosilane coupling agent and azobisisobutyronitrile are added. The mixture is reacted at 50-60°C for 3-4 hours, purified, and dried to obtain the modified polymer. S1-2: Add yttrium oxide to a 75wt%~85wt% aqueous ethanol solution, add an aminosilane coupling agent, react at 50~60℃ for 3~4h, add the modified polymer, add ammonia dropwise to adjust the pH to 8.3~8.7, stir at 60~80℃ for 1.5~2.5h, filter, wash and dry to obtain modified yttrium oxide; S1-3: Under a nitrogen atmosphere, hydrogen-containing silicone oil, allyl glycidyl ether, allyl polyoxyethylene polyoxypropylene ether, and platinum catalyst are added to xylene and reacted at 85~95℃ for 3~5h. Then, ethylenediamine is added and reacted at 80~90℃ for 3~5h. The mixture is then distilled under reduced pressure to obtain amino-modified polyether siloxane. S1-4: Amino-modified polyether siloxane, modified yttrium oxide, and triethylamine are added to xylene-tetrahydrofuran and reacted at 60-70℃ for 2-4 hours. After centrifugation and drying, modified polyether siloxane is obtained.

[0015] In a further embodiment, the mass ratio of xylene to tetrahydrofuran in the xylene-tetrahydrofuran raw material is 3:0.8~1.2.

[0016] In a further embodiment, the concentration of the ammonia water is 0.8~1.2 mol / L.

[0017] In a more optimized manner, the raw material for the modified polyether siloxane includes the following components: by mass, 2-3 parts of hydrogen-containing silicone oil, 0.05-0.1 parts of platinum catalyst, 2-3 parts of allyl polyoxyethylene polyoxypropylene ether, 3.2-6.5 parts of allyl glycidyl ether, 1.5-3 parts of ethylenediamine, 4-6 parts of modified yttrium oxide, and 0.1-0.15 parts of triethylamine; The raw material for the modified yttrium oxide includes the following components by mass: 4.4-6.8 parts hydroxyethyl methacrylate, 0.03-0.06 parts triethylamine, 2-3 parts hexachlorocyclotriphosphazene, 2.5-4.5 parts mercaptosilane coupling agent, 0.1-0.2 parts azobisisobutyronitrile, 5-6 parts yttrium oxide, 1-2.2 parts aminosilane coupling agent, and 4-6 parts modified polymer.

[0018] In a further embodiment, the platinum catalyst is a 25wt%~30wt% chloroplatinic acid solution.

[0019] A carbon-coated current collector is prepared by applying an aqueous coating onto the surface of the current collector and drying it to form an insulating coating, thereby obtaining the carbon-coated current collector.

[0020] Ideally, the thickness of the insulating coating is ≥2μm, and the width of the coating is 280~320mm.

[0021] Compared with the prior art, the present invention has the following beneficial effects: (1) In this scheme, aluminum hydrogen phosphate (Al(H2PO4)3) is used as a high-temperature binder to form stable phosphate products. Then, a high-temperature resistant and highly insulating ZrO2-Al2O3 material is successfully prepared by a simple and efficient co-precipitation method. The obtained ZrO2-Al2O3 is added to the insulating slurry as the main material to provide the coating with strong insulation. The insulating coating obtained by this water-based edge coating slurry has excellent insulation and safety. The coating can achieve complete insulation with a sheet resistance of ≥2μm thickness, and has no damage or effect on the coating at high temperatures below 500℃. The purpose of introducing aluminum hydrogen phosphate as a flame-retardant binder is mainly that this material can generate phosphate products such as AlPO4 and ZrP2O7 at high temperatures, which fundamentally improves the high-temperature resistance and flame-retardant performance of the insulating coating.

[0022] (2) This scheme uses modified polyether siloxane as a wetting agent to further improve insulation and high temperature resistance. Among them, yttrium oxide refines ZrO2-Al2O3 grains through lattice matching effect, improves coating density, reduces electron transport channels, and improves insulation; the silicon-phosphorus hybrid layer (modified polymer) forms a covalent interface with aluminum dihydrogen phosphate binder through PO-Al bonds, forming electron barrier and improving insulation. Yttrium oxide can form YOP bonds with binder to improve thermal stability, improve the thermal decomposition temperature of polyether siloxane, and reduce crack generation caused by thermal stress concentration; the silicon-phosphorus hybrid layer itself has a flame-retardant structure of POC bonds, which further improves the reduction of thermal decomposition temperature of polyether siloxane.

[0023] Meanwhile, the grafted allyl segments and the silicon-phosphorus hybrid layer provide steric hindrance and repulsion, improving dispersibility; the polyether segments interact with the binder through hydrogen bonding, enhancing the bonding force between the binder and the insulating material, and improving the overall stability of the coating. DETAILED DESCRIPTION

[0024] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0025] It should be noted that the following parts are by weight. There are no special restrictions on the manufacturers of the raw materials involved in this invention. Exemplary examples include: sodium hydroxide in flake form, grade AR, purity ≥96.0%; phosphoric acid, grade GR, purity ≥85.0%, national drug code 10015408, purchased from Sinopharm Group; alumina, grade AR, national drug code 10000917, purchased from Sinopharm Group; ammonia, grade for LC-MS, purity ≥25%, national drug code XW011336216024, purchased from Sinopharm Group; aluminum nitrate nonahydrate, grade AR, purity ≥99.0%, national drug code 80003616, purchased from Sinopharm Group; zirconium oxychloride, grade 36%, national drug code XW01769943602, purchased from Sinopharm Group; urea, grade Acros-C14075. 1 kg of anhydrous ethanol (C140750010, purchased from Sinopharm Group); anhydrous ethanol (AR grade, purity ≥99.7%, C10009218, purchased from Sinopharm Group); hydroxyethyl methacrylate (CAS number 868-77-9); triethylamine (CAS number 121-44-8); hexachlorocyclotriphosphazene (CAS number 940-71-6); mercaptopropyltrimethoxysilane (CAS number 4420-74-0); 3-aminopropyltriethoxysilane (CAS number 919-30-2); chloroplatinic acid (CAS number 16941-12). -1; Yttrium oxide, specification 50nm, item number 0821, purchased from Jiangsu Runfeng Synthetic Technology Co., Ltd.; Hydrogen-containing silicone oil with an active hydrogen mass fraction of 0.18%, CAS number 63148-57-2; Allyl polyoxyethylene polyoxypropylene ether, CAS number 69227-21-0, relative molecular mass 1300; Ethylenediamine, CAS number 107-15-3; Allyl glycidyl ether, CAS number 106-92-3; Hexacarbon perfluoropolyether siloxane, CAS number 1184727-90-9, relative molecular mass 1000.

[0026] The following embodiments are specifically illustrated as follows: (1) The mass ratio of xylene to tetrahydrofuran is 3:1; (2) The solid content of the adhesive solution is 40%; the viscosity of the adhesive solution is 2150 mPa·s; (3) The pH adjuster is a 0.5 mmol / L sodium hydroxide aqueous solution; the wetting agent is a modified polyether siloxane; and the insulating material is an Al2O3-ZrO2 composite powder.

[0027] Example 1: A water-based coating with both insulating and safe properties, and a carbon-coated current collector prepared therefrom, comprising the following steps: Step 1: Heat a 25wt% phosphoric acid aqueous solution to 70℃, then add alumina. The mass ratio of phosphoric acid to alumina is 2:1. Stir magnetically at 1000r / min for 1.5h at 85℃. Adjust the pH to 3.0 with 1mol / L ammonia. Evaporate and concentrate to a viscous state with a solid content of 40%. Let stand for 24h to obtain aluminum hydrogen phosphate binder. Step 2: Add aluminum nitrate nonahydrate and zirconium oxychloride to deionized water at a mass ratio of 8:2. Stir magnetically at 1000 r / min for 30 minutes until the solution is free of obvious impurities. Add 1 mol / L urea aqueous solution to adjust the pH to 9.5 to form Al(OH)3 and Zr(OH)4 coprecipitate. Wash the precipitate with deionized water and anhydrous ethanol. After dehydration with ethanol, dry in a vacuum drying oven at 80℃ for 12 hours. Calcine at 800℃ for 3 hours to obtain Al2O3-ZrO2 composite powder. Wash the calcined material again with ethanol. After washing multiple times, place the powder in a vacuum drying oven and dry at 80℃ for 12 hours for later use. Step 3: S1: Add 5.6 parts of hydroxyethyl methacrylate and 0.04 parts of triethylamine to tetrahydrofuran, add 2.5 parts of hexachlorocyclotriphosphazene, reflux at 65℃ for 24 h, filter, extract and dry; then add to tetrahydrofuran, under nitrogen atmosphere, add 3.5 parts of mercaptopropyltrimethoxysilane and 0.15 parts of azobisisobutyronitrile, react at 55℃ for 3.5 h, purify and dry to obtain the modified polymer; S2: Add 5.5 parts of yttrium oxide to 80wt% ethanol aqueous solution, add 1.5 parts of 3-aminopropyltriethoxysilane, react at 55℃ for 3.5 h, add 5 parts of modified polymer, and add 1mol / L ammonia water dropwise to adjust pH adjusted to 8.5, stirred at 70℃ for 2 hours, filtered, washed and dried to obtain modified yttrium oxide; S3: Under nitrogen atmosphere, 2.5 parts of hydrogen-containing silicone oil, 4.5 parts of allyl glycidyl ether, 2.5 parts of allyl polyoxyethylene polyoxypropylene ether, and 0.08 parts of 25wt% chloroplatinic acid solution were added to xylene and reacted at 90℃ for 4 hours. Then, 2.5 parts of ethylenediamine were added and reacted at 85℃ for 4 hours. The mixture was then distilled under reduced pressure to obtain amino-modified polyether siloxane; S4: Amino-modified polyether siloxane, 5 parts of modified yttrium oxide, and 0.12 parts of triethylamine were added to xylene-tetrahydrofuran and reacted at 65℃ for 3 hours. The mixture was then centrifuged and dried to obtain modified polyether siloxane; Step 4: Mix aluminum hydrogen phosphate binder with deionized water to obtain an adhesive solution; Step 5: Add one-third of the mass of insulating material and disperse at 2300 rpm / min for 30 min. Add one-third of the mass of insulating material and disperse at 2300 rpm / min for 30 min. Add the remaining insulating material and disperse at 2300 rpm / min for 60 min. Add deionized water and disperse again at 2300 rpm / min for 30 min. Add pH adjuster to adjust pH to 7.0. Add wetting agent and disperse at 12 rpm / min for 35 min. Then homogenize twice at a pressure of 600 bar to obtain water-based coating. Step 6: Apply water-based coating to the surface of the current collector with a width of 300 mm, dry it to form an insulating coating with a thickness of 2 μm, and obtain the carbon-coated current collector.

[0028] In the above embodiments, the amount of Al2O3-ZrO2 composite powder added accounts for 80 wt% of the solid content in the water-based coating; the amount of wetting agent added accounts for 10 wt% of the total mass of the water-based coating; and the amount of pH adjuster added accounts for 8 wt% of the solid content in the water-based coating.

[0029] Example 2: A water-based coating with common insulation and safety properties and the carbon-coated current collector prepared therefrom, based on Example 1; the amount of Al2O3-ZrO2 composite powder added accounts for 70 wt% of the solid content in the water-based coating, and the rest is the same as in Example 1.

[0030] Example 3: A water-based coating with common insulation and safety properties and the carbonized current collector prepared therefrom, based on Example 1; the amount of Al2O3-ZrO2 composite powder added accounts for 60 wt% of the solid content in the water-based coating, and the rest is the same as in Example 1.

[0031] Example 4: A water-based coating with common insulation and safety properties and the carbonized current collector prepared therefrom, based on Example 1; the amount of Al2O3-ZrO2 composite powder added accounts for 50 wt% of the solid content in the water-based coating, and the rest is the same as in Example 1.

[0032] Example 5: A water-based coating with common insulation and safety properties and the carbon-coated current collector prepared therefrom, based on Example 1, is modified as follows: Step 1: 25wt% phosphoric acid aqueous solution is heated to 70°C, and then alumina is added. The mass ratio of phosphoric acid to alumina is 2:1. The mixture is magnetically stirred at 1000r / min for 1.5h at 85°C. The mixture is then evaporated and concentrated to a viscous state with a solid content of 40%. After standing for 24h, aluminum hydrogen phosphate binder is obtained.

[0033] Comparative Example 1: Based on Example 1, conventional PAA was used instead of aluminum hydrogen phosphate binder, while the rest of the process remained unchanged.

[0034] Comparative Example 2: Based on Example 1, without modified polymer (silicon-phosphorus hybrid layer), and with the remaining processes unchanged, specifically: Step 3: S1: Add 5.5 parts of yttrium oxide to an 80wt% aqueous ethanol solution, add 1.8 parts of vinyltrimethoxysilane, react at 65℃ for 4h, adjust the pH to 9 by adding 1mol / L ammonia dropwise, stir at 70℃ for 2h, filter, wash and dry to obtain modified yttrium oxide; S2: Under a nitrogen atmosphere, add 2.5 parts of hydrogen-containing silicone oil, 4.5 parts of allyl glycidyl ether, 2.5 parts of allyl polyoxyethylene polyoxypropylene ether, and 0.08 parts of 25wt% chloroplatinic acid solution to xylene, react at 90℃ for 4h, add 2.5 parts of ethylenediamine, react at 85℃ for 4h, and distill under reduced pressure to obtain amino-modified polyether siloxane; S3: Add amino-modified polyether siloxane, 5 parts of modified yttrium oxide, and 0.12 parts of triethylamine to xylene-tetrahydrofuran, react at 65℃ for 3h, centrifuge and dry to obtain modified polyether siloxane.

[0035] Comparative Example 3: Based on Example 1, without the addition of yttrium oxide, with the remaining processes unchanged, specifically: Step 3: Under a nitrogen atmosphere, 2.5 parts of hydrogen-containing silicone oil, 4.5 parts of allyl glycidyl ether, 2.5 parts of allyl polyoxyethylene polyoxypropylene ether, and 0.08 parts of 25wt% chloroplatinic acid solution were added to xylene and reacted at 90℃ for 4 hours. Then, 2.5 parts of ethylenediamine were added and reacted at 85℃ for 4 hours. The mixture was then distilled under reduced pressure to obtain modified polyether siloxane.

[0036] Comparative Example 4: Based on Example 1, without adding amino-modified polyether siloxane, and with the rest of the process unchanged, specifically: Step 3: S1: Add 5.6 parts of hydroxyethyl methacrylate and 0.04 parts of triethylamine to tetrahydrofuran, add 2.5 parts of hexachlorocyclotriphosphazene, reflux at 65°C for 24 h, filter, extract and dry; then add to tetrahydrofuran, under nitrogen atmosphere, add 3.5 parts of mercaptopropyltrimethoxysilane and 0.15 parts of azobisisobutyronitrile, react at 55°C for 3.5 h, purify and dry to obtain the modified polymer; S2: Add 5.5 parts of yttrium oxide to 80 wt% ethanol aqueous solution, add 1 0.5 parts of 3-aminopropyltriethoxysilane were reacted at 55°C for 3.5 h, 4.5 parts of modified polymer were added, and 1 mol / L ammonia was added dropwise to adjust the pH to 8.5. The mixture was stirred at 70°C for 2 h, filtered, washed, and dried to obtain modified yttrium oxide; S3: 2.5 parts of hexacarbon perfluoropolyether siloxane, 5 parts of modified yttrium oxide, 0.12 parts of triethylamine, and 0.03 parts of boron trifluoride ethyl ether were added to xylene-tetrahydrofuran and reacted at 60°C for 4 h. The mixture was then centrifuged and dried to obtain modified polyether siloxane.

[0037] Test experiment: The carbon-coated current collectors prepared in Examples 1-5 and Comparative Examples 1-4 were tested for their performance: (1) Sheet resistance and penetration resistance test: Several 20cm×5cm carbon-coated current collectors were taken and the surface sheet resistance was tested using a four-probe sheet resistance meter; the carbon-coated current collectors were cut into 5cm×5cm pieces and the penetration resistance was measured using a diaphragm resistance meter. The data were recorded respectively; the results are shown in Table 1.

[0038] Results Analysis: According to the data analysis in Table 1, this scheme uses aluminum hydrogen phosphate (Al(H2PO4)3) as a high-temperature binder and ZrO2-Al2O3 as an insulating slurry, which can directly reduce the risk of battery short circuit and thermal runaway, meeting the high safety standards of power batteries (such as electric vehicles); reduce edge side reactions (such as lithium plating and corrosion), and extend cycle life; and through edge protection, the electrode thickness or material system can be more aggressively optimized.

[0039] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

Claims

1. A water-based coating that provides both insulation and safety, characterized in that: The preparation method of the water-based coating is as follows: Step 1: Mix aluminum hydrogen phosphate binder with deionized water to obtain an adhesive solution; Step 2: Add the insulating material to the adhesive solution in three batches, disperse at high speed of 2000~2600 rpm / min for 30~60 min, add deionized water and disperse at high speed again for 30~60 min, add pH adjuster to adjust pH to 6.9~7.1, add wetting agent and disperse at low speed of 10~15 rpm / min for 30~45 min, then homogenize at a pressure of 550~650 bar 2~3 times to obtain water-based coating.

2. The water-based coating with insulation and safety as described in claim 1, characterized in that: The insulating material is Al2O3-ZrO2 composite powder; the amount of Al2O3-ZrO2 composite powder added accounts for 50wt%~80wt% of the solid content in the water-based coating; the amount of wetting agent added accounts for 8wt%~12wt% of the total mass of the water-based coating.

3. The water-based coating with insulation and safety as described in claim 1, characterized in that: The preparation process of the aluminum hydrogen phosphate binder is as follows: a 20wt%~30wt% aqueous solution of phosphoric acid is heated to 60~80℃, and then aluminum oxide is added. The mass ratio of phosphoric acid to aluminum oxide is 2:0.9~1.

1. The mixture is stirred at 80~90℃ for 1~2 hours, the pH is adjusted to 2.0~4.0 with ammonia water, and the mixture is concentrated to a solid content of 30~50% to obtain the aluminum hydrogen phosphate binder.

4. The water-based coating with insulating and safe properties according to claim 1, characterized in that: The solid content of the adhesive solution is 30-50%; the viscosity of the adhesive solution is 800-3500 mPa·s.

5. The water-based coating with insulation and safety as described in claim 2, characterized in that: The preparation process of the Al2O3-ZrO2 composite powder is as follows: aluminum nitrate nonahydrate and zirconium oxychloride are added to deionized water at a mass ratio of 8:1.9~2.1, urea aqueous solution is added to adjust the pH to 9.0~10.0 to form a coprecipitate, and after washing and drying, it is calcined at 600~1000℃ for 2~4h to obtain Al2O3-ZrO2 composite powder.

6. The method for preparing a water-based coating with insulating and safe properties according to claim 1, characterized in that: The pH adjuster is a 0.4~0.6 mmol / L sodium hydroxide aqueous solution; the amount of the pH adjuster added accounts for 5wt%~10wt% of the solid content in the water-based coating; the wetting agent includes one or more of polyether siloxane, modified polyether siloxane, and alcohol reagents.

7. The water-based coating with insulation and safety as described in claim 6, characterized in that: When the wetting agent is a modified polyether siloxane, the preparation process of the modified polyether siloxane is as follows: S1-1: Hydroxyethyl methacrylate and triethylamine are added to tetrahydrofuran, hexachlorocyclotriphosphazene is added, and the mixture is refluxed at 60~70℃ for 20~28h, filtered, extracted and dried; then added to tetrahydrofuran, under a nitrogen atmosphere, mercaptosilane coupling agent and azobisisobutyronitrile are added, and the mixture is reacted at 50~60℃ for 3~4h, purified and dried to obtain the modified polymer; S1-2: Add yttrium oxide to a 75wt%~85wt% aqueous ethanol solution, add an aminosilane coupling agent, react at 50~60℃ for 3~4h, add the modified polymer, add ammonia dropwise to adjust the pH to 8.3~8.7, stir at 60~80℃ for 1.5~2.5h, filter, wash and dry to obtain modified yttrium oxide; S1-3: Under a nitrogen atmosphere, hydrogen-containing silicone oil, allyl glycidyl ether, allyl polyoxyethylene polyoxypropylene ether, and platinum catalyst are added to xylene and reacted at 85~95℃ for 3~5h. Then, ethylenediamine is added and reacted at 80~90℃ for 3~5h. The mixture is then distilled under reduced pressure to obtain amino-modified polyether siloxane. S1-4: Amino-modified polyether siloxane, modified yttrium oxide, and triethylamine are added to xylene-tetrahydrofuran and reacted at 60-70℃ for 2-4 hours. After centrifugation and drying, modified polyether siloxane is obtained.

8. The water-based coating with insulation and safety as described in claim 7, characterized in that: The modified polyether siloxane raw material comprises the following components by mass: 2-3 parts hydrogen-containing silicone oil, 0.05-0.1 parts platinum catalyst, 2-3 parts allyl polyoxyethylene polyoxypropylene ether, 3.2-6.5 parts allyl glycidyl ether, 1.5-3 parts ethylenediamine, 4-6 parts modified yttrium oxide, and 0.1-0.15 parts triethylamine; The raw material for the modified yttrium oxide includes the following components by mass: 4.4-6.8 parts hydroxyethyl methacrylate, 0.03-0.06 parts triethylamine, 2-3 parts hexachlorocyclotriphosphazene, 2.5-4.5 parts mercaptosilane coupling agent, 0.1-0.2 parts azobisisobutyronitrile, 5-6 parts yttrium oxide, 1-2.2 parts aminosilane coupling agent, and 4-6 parts modified polymer.

9. A carbon-coated current collector, characterized in that: The carbon-coated current collector prepared by an aqueous coating with common insulation and safety according to any one of claims 1 to 8 is prepared by: applying an aqueous coating to the surface of the current collector, drying it to form an insulating coating, and obtaining the carbon-coated current collector.

10. A carbon-coated current collector according to claim 9, characterized in that: The thickness of the insulating coating is ≥2μm; the width of the coating is 280~320mm.

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