Conductive coating for high-temperature-resistant lithium battery and preparation method of conductive coating

Abstract

The invention discloses a conductive coating for a high-temperature-resistant lithium battery and a preparation method thereof.The conductive coating is prepared from, by weight, 80-100 parts of modified resin, 3-5 parts of silver powder, 10-15 parts of carbon black, 10-15 parts of graphene and 150-200 parts of N-methyl-2-pyrrolidone, in the blending process of the raw materials, sulfydryl on the modified resin and anions of the silver powder can form a coordinate bond, and therefore the conductive coating is formed. The modified resin contains an anthraquinone structure, the molecular structure of the anthraquinone structure has a conjugated pi electron system, and the conjugated structure can promote delocalization of electrons, so that an electron transmission channel is formed, and the conductivity of the coating is ensured; the three-dimensional structure of the modified resin can enhance the interaction between molecules and improve the thermal stability of the material, and the modified resin is matched with organic silicon chain segments in the molecules, so that the prepared conductive coating has a very good high-temperature-resistant effect.

Description

Technical Field

[0001] The present invention relates to the technical field of preparation of conductive coatings for lithium batteries, and in particular to a conductive coating for high-temperature resistant lithium batteries and a preparation method thereof. Background Art

[0002] Lithium-ion battery refers to the general term for batteries with lithium-ion embedded compounds as the positive electrode material. It is a rechargeable battery that relies on the movement of lithium ions between the positive and negative electrodes to work. Due to the excellent charge and discharge capabilities of lithium-ion batteries, they are widely used in electronic equipment, submarines, torpedoes, drones, electric vehicles, grid energy storage, etc. At present, the energy density, power density and cycle life of lithium-ion batteries have been significantly improved, but there are still hidden dangers in terms of safety. Although lithium-ion batteries have excellent charge and discharge capabilities, high temperatures will appear inside the battery during the charge and discharge process, which may cause the coating coated on the surface of the current collector to fall off due to thermal expansion and the coating aging process to accelerate, causing the coating to be damaged, thereby increasing the contact resistance between the current collector and the active material, causing the battery to short circuit, which has a great safety hazard. Summary of the Invention

[0003] The purpose of the present invention is to provide a conductive coating for high-temperature resistant lithium batteries and a preparation method thereof, which solves the problem that the conductive coating for lithium batteries currently falls off in high-temperature environments and the conductivity decreases significantly, affecting the normal use of the battery.

[0004] The purpose of the present invention can be achieved through the following technical solutions:

[0005] A method for preparing a conductive coating for a high-temperature resistant lithium battery comprises the following steps:

[0006] Step A1: lithium dimethylhydrogensilanol and tetrahydrofuran are uniformly mixed, stirred at a speed of 120-150 r / min and a temperature of 0°C, and octamethylcyclotetrasiloxane is added. The temperature is raised to 25-30°C, and the reaction is carried out for 7-9 hours to obtain an intermediate. The intermediate, modified polyurethane, and tetrahydrofuran are mixed, and the reaction is carried out at a speed of 200-300 r / min and a temperature of 25-30°C for 1-1.5 hours to obtain a functionalized polyurethane.

[0007] Step A2: functionalized polyurethane, modifier, chloroplatinic acid and DMF are mixed, nitrogen is introduced, and the reaction is carried out at a speed of 120-150 r / min and a temperature of 75-85° C. for 8-10 hours to prepare a pretreated resin; thioglycolic acid, p-toluenesulfonic acid, triphenyl phosphite and DMF are mixed uniformly, nitrogen is introduced, and the pretreated resin is added to the mixture at a speed of 150-200 r / min and a temperature of 65-70° C., and the temperature is raised to 80-85° C. and the reaction is carried out for 8-10 hours to prepare a modified resin;

[0008] Step A3: Weigh the following raw materials in parts by weight: 80-100 parts of modified resin, 3-5 parts of silver powder, 10-15 parts of carbon black, 10-15 parts of graphene and 150-200 parts of N-methylpyrrolidone, and mix the raw materials evenly at a temperature of 40-60°C to prepare a high-temperature resistant conductive coating for lithium batteries.

[0009] Furthermore, the molar ratio of lithium dimethylhydrogensilanol and octamethylcyclotetrasiloxane in step A1 is 1:3, and the molar ratio of Si-Cl bonds on the intermediate and the modified polyurethane is 1:1.

[0010] Furthermore, the molar ratio of the Si-H bond on the functionalized polyurethane described in step A2 to the modifier is 1:1, the amount of chloroplatinic acid is 1‰ of the mass of the modifier, the molar ratio of thioglycolic acid to the hydroxyl group on the pretreated resin is 1:1, the amount of p-toluenesulfonic acid is 2% of the mass of thioglycolic acid, and the amount of triphenyl phosphite is 1‰ of the mass of thioglycolic acid.

[0011] Furthermore, the modified polyurethane is prepared by the following steps:

[0012] Step B1: Acrylic acid, diethanolamine, p-toluenesulfonic acid and dimethyl sulfoxide are mixed, nitrogen is introduced into the mixture, and the reaction is carried out at a speed of 120-150 r / min and a temperature of 60-80° C. for 3-5 hours to obtain a modifier; octamethylcyclotetrasiloxane, tetramethyltetraphenylcyclotetrasiloxane, tetramethylammonium hydroxide, 1,1,3,3-tetramethyldisiloxane and dichlorothione are mixed uniformly, nitrogen is introduced into the mixture, the reaction is carried out at a speed of 120-150 r / min and a temperature of 90-95° C. for 10-12 hours, and then the temperature is raised to 105-110° C. and the reaction is continued for 2-3 hours to obtain polysiloxane;

[0013] Step B2: polysiloxane, a modifier, chloroplatinic acid, and DMF are mixed, nitrogen is introduced, and the mixture is reacted at a speed of 120-150 r / min and a temperature of 75-85° C. for 6-8 hours to obtain a modified monomer; polytetrahydrofuran diol, 1,4-aminoanthraquinone, and acetone are uniformly mixed, nitrogen is introduced, and isophorone diisocyanate and dibutyltin dilaurate are added to the mixture at a speed of 150-200 r / min and a temperature of 60-65° C. with stirring, and the mixture is reacted for 2-3 hours to obtain a polyurethane prepolymer;

[0014] Step B3: The polyurethane prepolymer, the modified monomer and DMF are uniformly mixed, stirred and dibutyltin dilaurate is added at a speed of 200-300 r / min and a temperature of 65-70°C, and the reaction is carried out for 30-40 minutes. Hydroxyethyl methacrylate is added and the reaction is carried out for 2-3 hours to obtain a pretreated polyurethane. The pretreated polyurethane, trichlorosilane, chloroplatinic acid and DMF are mixed, nitrogen protection is introduced, and the reaction is carried out at a speed of 120-150 r / min and a temperature of 75-85°C for 6-8 hours to obtain a modified polyurethane.

[0015] Furthermore, the molar ratio of acrylic acid and diethanolamine in step B1 is 1:1, the amount of p-toluenesulfonic acid is 2% by mass of acrylic acid and diethanolamine, and the amount ratio of octamethylcyclotetrasiloxane, tetramethyltetraphenylcyclotetrasiloxane, tetramethylammonium hydroxide, 1,1,3,3-tetramethyldisiloxane and dichloride is 3.5 mol:1.3 mol:6 mol:4 mol:8 L.

[0016] Furthermore, the molar ratio of the polysiloxane and the modifier described in step B2 is 1:2, the amount of chloroplatinic acid is 1‰ of the mass of the modifier, the molar ratio of polytetrahydrofuran diol, 1,4-diaminoanthraquinone and isophorone diisocyanate is 1:1:3, and the amount of dibutyltin dilaurate is 3% of the mass of polytetrahydrofuran diol.

[0017] Furthermore, the molar ratio of the polyurethane prepolymer, modified monomer and hydroxyethyl methacrylate in step B3 is 3n+1:n:2n+2, where n is a natural number greater than 0, the molar ratio of the double bond on the pretreated polyurethane and trichlorosilane is 1:1, and the amount of chloroplatinic acid used is 1‰ of the mass of trichlorosilane.

[0018] Beneficial effects of the present invention: A conductive coating for high-temperature resistant lithium batteries prepared in the present application includes the following raw materials: modified resin, silver powder, carbon black, graphene and N-methylpyrrolidone, the modified resin uses dimethylhydrogen silicon lithium as an initiator and octamethylcyclotetrasiloxane as a polymerization monomer to prepare an intermediate, the intermediate is reacted with modified polyurethane, so that the lithium silicon on the intermediate reacts with the Si-Cl bond on the modified polyurethane to prepare functionalized polyurethane, the functionalized polyurethane is reacted with a modifier, so that the Si-H bond on the functionalized polyurethane reacts with the double bond on the modifier to prepare a pretreated resin, the pretreated resin is reacted with thioglycolic acid, so that the hydroxyl group on the pretreated resin reacts with the carboxyl group on the thioglycolic acid to prepare a modified resin.

[0019] The modified polyurethane uses acrylic acid and diethanolamine as raw materials, reacts the carboxyl group on the acrylic acid with the secondary amine of the diethanolamine to prepare a modifier, performs ring-opening condensation on octamethylcyclotetrasiloxane and tetramethyltetraphenylcyclotetrasiloxane, and then uses 1,1,3,3-tetramethyldisiloxane to block the end to prepare polysiloxane, reacts the polysiloxane with the modifier, reacts the Si-H bond on the polysiloxane with the double bond on the modifier to prepare a modified monomer, reacts polytetrahydrofuran, 1,4-diaminoanthraquinone and isophorone diisocyanate to form a prepolymer structure to prepare a polyurethane prepolymer, reacts the polyurethane prepolymer with the modified monomer to form a hyperbranched structure, and then uses hydroxyethyl methacrylate to block the end to prepare a pretreated polyurethane, and reacts the pretreated polyurethane with trichlorosilane, so that the double bond on the pretreated polyurethane reacts with the Si-H bond on the trichlorosilane to prepare the modified polyurethane.

[0020] During the raw material blending process, the thiol group on the modified resin can form a coordination bond with the silver powder anion, thereby strengthening the contact between the conductive silver powder and the modified resin, which is conducive to the formation of a conductive path. The modified resin molecule contains an anthraquinone structure, and its molecular structure has a conjugated π electron system. This conjugated structure can promote the delocalization of electrons, thereby forming an electron transmission channel to ensure the conductivity of the coating. The three-dimensional structure of the modified resin can enhance the interaction between molecules and improve the thermal stability of the material. This structure brings the distance between molecules closer, and the van der Waals force and hydrogen bond between molecules are enhanced, thereby improving the high temperature resistance of the material. Combined with the organic silicon chain segment inside the molecule, the prepared conductive coating has a good high temperature resistance effect.

[0021] Specific implementation method

[0022] 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 part of the embodiments of the present invention, not all of them. 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.

[0023] Example 1, a method for preparing a conductive coating for a high-temperature resistant lithium battery, specifically comprising the following steps:

[0024] Step A1: lithium dimethylhydrogensilanol and tetrahydrofuran are uniformly mixed, stirred at a speed of 120 r / min and a temperature of 0°C, and octamethylcyclotetrasiloxane is added. The temperature is raised to 25°C, and the reaction is carried out for 7 hours to obtain an intermediate. The intermediate, modified polyurethane, and tetrahydrofuran are mixed, and the reaction is carried out at a speed of 200 r / min and a temperature of 25°C for 1 hour to obtain a functionalized polyurethane.

[0025] Step A2: functionalized polyurethane, modifier, chloroplatinic acid, and DMF were mixed, nitrogen was introduced, and the reaction was carried out at a speed of 120 r / min and a temperature of 75°C for 8 hours to prepare a pretreated resin; thioglycolic acid, p-toluenesulfonic acid, triphenyl phosphite, and DMF were mixed uniformly, nitrogen was introduced, and the pretreated resin was added to the mixture at a speed of 150 r / min and a temperature of 65°C. The mixture was heated to 80°C and the reaction was carried out for 8 hours to prepare a modified resin;

[0026] Step A3: Weigh the following raw materials in parts by weight: 80 parts of modified resin, 3 parts of silver powder, 10 parts of carbon black, 10 parts of graphene and 150 parts of N-methylpyrrolidone, mix the raw materials evenly at a temperature of 40°C to prepare a high-temperature resistant conductive coating for lithium batteries.

[0027] The molar ratio of lithium dimethylhydrogensilanol and octamethylcyclotetrasiloxane in step A1 is 1:3, and the molar ratio of Si-Cl bonds on the intermediate and the modified polyurethane is 1:1.

[0028] The molar ratio of the Si-H bond on the functionalized polyurethane described in step A2 to the modifier is 1:1, the amount of chloroplatinic acid is 1‰ of the mass of the modifier, the molar ratio of thioglycolic acid to the hydroxyl group on the pretreated resin is 1:1, the amount of p-toluenesulfonic acid is 2% of the mass of thioglycolic acid, and the amount of triphenyl phosphite is 1‰ of the mass of thioglycolic acid.

[0029] The modified polyurethane is prepared by the following steps:

[0030] Step B1: Acrylic acid, diethanolamine, p-toluenesulfonic acid and dimethyl sulfoxide were mixed, nitrogen was introduced, and the reaction was carried out at a speed of 120 r / min and a temperature of 60°C for 3 hours to obtain a modifier. Octamethylcyclotetrasiloxane, tetramethyltetraphenylcyclotetrasiloxane, tetramethylammonium hydroxide, 1,1,3,3-tetramethyldisiloxane and dichlorothione were mixed, nitrogen was introduced, the reaction was carried out at a speed of 120 r / min and a temperature of 90°C for 10 hours, and then the temperature was raised to 105°C and the reaction was continued for 2 hours to obtain polysiloxane;

[0031] Step B2: polysiloxane, a modifier, chloroplatinic acid, and DMF were mixed, nitrogen was introduced, and the mixture was reacted at a speed of 120 r / min and a temperature of 75° C. for 6 hours to obtain a modified monomer. Polytetrahydrofuran diol, 1,4-diaminoanthraquinone, and acetone were mixed uniformly, nitrogen was introduced, and isophorone diisocyanate and dibutyltin dilaurate were added with stirring at a speed of 150 r / min and a temperature of 60° C. to obtain a polyurethane prepolymer.

[0032] Step B3: The polyurethane prepolymer, the modified monomer, and DMF were uniformly mixed, and dibutyltin dilaurate was added under stirring at a speed of 200 r / min and a temperature of 65° C., and the mixture was reacted for 30 minutes. Hydroxyethyl methacrylate was added and the mixture was reacted for 2 hours to obtain a pretreated polyurethane. The pretreated polyurethane, trichlorosilane, chloroplatinic acid, and DMF were mixed, nitrogen was introduced, and the mixture was reacted at a speed of 120 r / min and a temperature of 75° C. for 6 hours to obtain a modified polyurethane.

[0033] The molar ratio of acrylic acid and diethanolamine in step B1 is 1:1, the amount of p-toluenesulfonic acid used is 2% by mass of acrylic acid and diethanolamine, and the amount ratio of octamethylcyclotetrasiloxane, tetramethyltetraphenylcyclotetrasiloxane, tetramethylammonium hydroxide, 1,1,3,3-tetramethyldisiloxane and dithionyl chloride is 3.5 mol:1.3 mol:6 mol:4 mol:8 L.

[0034] The molar ratio of the polysiloxane and the modifier described in step B2 is 1:2, the amount of chloroplatinic acid is 1% of the mass of the modifier, the molar ratio of polytetrahydrofuran diol, 1,4-diaminoanthraquinone and isophorone diisocyanate is 1:1:3, the amount of dibutyltin dilaurate is 3% of the mass of polytetrahydrofuran diol, and the molecular weight of polytetrahydrofuran diol is 2000.

[0035] The molar ratio of the polyurethane prepolymer, modified monomer and hydroxyethyl methacrylate in step B3 is 4:1:4, the molar ratio of the double bond on the pretreated polyurethane and trichlorosilane is 1:1, and the amount of chloroplatinic acid used is 1‰ of the mass of trichlorosilane.

[0036] Example 2, a method for preparing a conductive coating for a high-temperature resistant lithium battery, specifically comprising the following steps:

[0037] Step A1: lithium dimethylhydrogensilanol and tetrahydrofuran are uniformly mixed, stirred at a speed of 120 r / min and a temperature of 0°C, and octamethylcyclotetrasiloxane is added. The temperature is raised to 25-30°C, and the reaction is carried out for 8 hours to obtain an intermediate. The intermediate, modified polyurethane, and tetrahydrofuran are mixed, and the reaction is carried out at a speed of 200 r / min and a temperature of 28°C for 1.5 hours to obtain a functionalized polyurethane.

[0038] Step A2: functionalized polyurethane, modifier, chloroplatinic acid, and DMF were mixed, nitrogen was introduced, and the reaction was carried out at a speed of 120 r / min and a temperature of 80°C for 9 hours to prepare a pretreated resin; thioglycolic acid, p-toluenesulfonic acid, triphenyl phosphite, and DMF were mixed uniformly, nitrogen was introduced, and the pretreated resin was added to the mixture at a speed of 200 r / min and a temperature of 70°C. The mixture was heated to 80°C and the reaction was carried out for 9 hours to prepare a modified resin;

[0039] Step A3: Weigh the following raw materials in parts by weight: 90 parts of modified resin, 4 parts of silver powder, 12 parts of carbon black, 12 parts of graphene and 180 parts of N-methylpyrrolidone, and mix the raw materials evenly at a temperature of 50°C to prepare a high-temperature resistant conductive coating for lithium batteries.

[0040] The molar ratio of lithium dimethylhydrogensilanol and octamethylcyclotetrasiloxane in step A1 is 1:3, and the molar ratio of Si-Cl bonds on the intermediate and the modified polyurethane is 1:1.

[0041] The molar ratio of the Si-H bond on the functionalized polyurethane described in step A2 to the modifier is 1:1, the amount of chloroplatinic acid is 1‰ of the mass of the modifier, the molar ratio of thioglycolic acid to the hydroxyl group on the pretreated resin is 1:1, the amount of p-toluenesulfonic acid is 2% of the mass of thioglycolic acid, and the amount of triphenyl phosphite is 1‰ of the mass of thioglycolic acid.

[0042] The modified polyurethane is prepared by the following steps:

[0043] Step B1: Acrylic acid, diethanolamine, p-toluenesulfonic acid and dimethyl sulfoxide were mixed, nitrogen was introduced, and the reaction was carried out at a speed of 120 r / min and a temperature of 70°C for 4 hours to obtain a modifier. Octamethylcyclotetrasiloxane, tetramethyltetraphenylcyclotetrasiloxane, tetramethylammonium hydroxide, 1,1,3,3-tetramethyldisiloxane and dichlorothione were mixed, nitrogen was introduced, the reaction was carried out at a speed of 150 r / min and a temperature of 90°C for 12 hours, and then the temperature was raised to 108°C and the reaction was continued for 3 hours to obtain polysiloxane;

[0044] Step B2: polysiloxane, a modifier, chloroplatinic acid, and DMF were mixed, nitrogen was introduced, and the mixture was reacted at a speed of 120 r / min and a temperature of 80° C. for 7 hours to obtain a modified monomer. Polytetrahydrofuran diol, 1,4-diaminoanthraquinone, and acetone were uniformly mixed, nitrogen was introduced, and isophorone diisocyanate and dibutyltin dilaurate were added with stirring at a speed of 150 r / min and a temperature of 65° C. to obtain a polyurethane prepolymer.

[0045] Step B3: The polyurethane prepolymer, the modified monomer, and DMF were uniformly mixed, and dibutyltin dilaurate was added under stirring at a speed of 300 r / min and a temperature of 65° C., and the mixture was reacted for 35 minutes. Hydroxyethyl methacrylate was added and the mixture was reacted for 3 hours to obtain a pretreated polyurethane. The pretreated polyurethane, trichlorosilane, chloroplatinic acid, and DMF were mixed, and nitrogen was introduced. The mixture was reacted at a speed of 120 r / min and a temperature of 80° C. for 7 hours to obtain a modified polyurethane.

[0046] The molar ratio of acrylic acid and diethanolamine in step B1 is 1:1, the amount of p-toluenesulfonic acid used is 2% by mass of acrylic acid and diethanolamine, and the amount ratio of octamethylcyclotetrasiloxane, tetramethyltetraphenylcyclotetrasiloxane, tetramethylammonium hydroxide, 1,1,3,3-tetramethyldisiloxane and dithionyl chloride is 3.5 mol:1.3 mol:6 mol:4 mol:8 L.

[0047] The molar ratio of the polysiloxane and the modifier described in step B2 is 1:2, the amount of chloroplatinic acid is 1‰ of the mass of the modifier, the molar ratio of polytetrahydrofuran diol, 1,4-diaminoanthraquinone and isophorone diisocyanate is 1:1:3, the amount of dibutyltin dilaurate is 3% of the mass of polytetrahydrofuran diol, and the molecular weight of polytetrahydrofuran diol is 2000.

[0048] The molar ratio of the polyurethane prepolymer, modified monomer and hydroxyethyl methacrylate in step B3 is 7:2:6, the molar ratio of the double bond on the pretreated polyurethane and trichlorosilane is 1:1, and the amount of chloroplatinic acid used is 1‰ of the mass of trichlorosilane.

[0049] Example 3, a method for preparing a conductive coating for a high-temperature resistant lithium battery, specifically comprising the following steps:

[0050] Step A1: lithium dimethylhydrogensilanol and tetrahydrofuran were uniformly mixed, stirred at a speed of 150 r / min and a temperature of 0°C, and octamethylcyclotetrasiloxane was added. The temperature was raised to 30°C, and the reaction was carried out for 9 hours to obtain an intermediate. The intermediate, modified polyurethane, and tetrahydrofuran were mixed, and the reaction was carried out at a speed of 300 r / min and a temperature of 30°C for 1.5 hours to obtain a functionalized polyurethane.

[0051] Step A2: functionalized polyurethane, modifier, chloroplatinic acid, and DMF were mixed, nitrogen was introduced, and the reaction was carried out at a speed of 150 r / min and a temperature of 85° C. for 10 hours to prepare a pretreated resin; thioglycolic acid, p-toluenesulfonic acid, triphenyl phosphite, and DMF were mixed uniformly, nitrogen was introduced, and the pretreated resin was added to the mixture at a speed of 200 r / min and a temperature of 70° C., and the temperature was raised to 85° C. and the reaction was carried out for 10 hours to prepare a modified resin;

[0052] Step A3: Weigh the following raw materials in parts by weight: 100 parts of modified resin, 5 parts of silver powder, 15 parts of carbon black, 15 parts of graphene and 200 parts of N-methylpyrrolidone, and mix the raw materials evenly at a temperature of 60°C to prepare a high-temperature resistant conductive coating for lithium batteries.

[0053] The molar ratio of lithium dimethylhydrogensilanol and octamethylcyclotetrasiloxane in step A1 is 1:3, and the molar ratio of Si-Cl bonds on the intermediate and the modified polyurethane is 1:1.

[0054] The molar ratio of the Si-H bond on the functionalized polyurethane described in step A2 to the modifier is 1:1, the amount of chloroplatinic acid is 1‰ of the mass of the modifier, the molar ratio of thioglycolic acid to the hydroxyl group on the pretreated resin is 1:1, the amount of p-toluenesulfonic acid is 2% of the mass of thioglycolic acid, and the amount of triphenyl phosphite is 1‰ of the mass of thioglycolic acid.

[0055] The modified polyurethane is prepared by the following steps:

[0056] Step B1: Acrylic acid, diethanolamine, p-toluenesulfonic acid and dimethyl sulfoxide were mixed, nitrogen was introduced, and the reaction was carried out at a speed of 150 r / min and a temperature of 80°C for 5 hours to obtain a modifier. Octamethylcyclotetrasiloxane, tetramethyltetraphenylcyclotetrasiloxane, tetramethylammonium hydroxide, 1,1,3,3-tetramethyldisiloxane and dichlorothione were mixed, nitrogen was introduced, the reaction was carried out at a speed of 150 r / min and a temperature of 95°C for 12 hours, and then the temperature was raised to 110°C and the reaction was continued for 3 hours to obtain polysiloxane;

[0057] Step B2: polysiloxane, a modifier, chloroplatinic acid, and DMF were mixed, nitrogen was introduced into the mixture, and the reaction was carried out at a speed of 150 r / min and a temperature of 85° C. for 8 hours to obtain a modified monomer. Polytetrahydrofuran diol, 1,4-diaminoanthraquinone, and acetone were uniformly mixed, nitrogen was introduced into the mixture, and isophorone diisocyanate and dibutyltin dilaurate were added thereto under stirring at a speed of 200 r / min and a temperature of 65° C., and the mixture was reacted for 3 hours to obtain a polyurethane prepolymer.

[0058] Step B3: The polyurethane prepolymer, the modified monomer, and DMF were uniformly mixed, and dibutyltin dilaurate was added under stirring at a speed of 300 r / min and a temperature of 70°C, and the reaction was carried out for 40 minutes. Hydroxyethyl methacrylate was added and the reaction was carried out for 3 hours to obtain a pretreated polyurethane. The pretreated polyurethane, trichlorosilane, chloroplatinic acid, and DMF were mixed, nitrogen was introduced, and the reaction was carried out at a speed of 150 r / min and a temperature of 85°C for 8 hours to obtain a modified polyurethane.

[0059] The molar ratio of acrylic acid and diethanolamine in step B1 is 1:1, the amount of p-toluenesulfonic acid used is 2% by mass of acrylic acid and diethanolamine, and the amount ratio of octamethylcyclotetrasiloxane, tetramethyltetraphenylcyclotetrasiloxane, tetramethylammonium hydroxide, 1,1,3,3-tetramethyldisiloxane and dithionyl chloride is 3.5 mol:1.3 mol:6 mol:4 mol:8 L.

[0060] The molar ratio of the polysiloxane and the modifier described in step B2 is 1:2, the amount of chloroplatinic acid is 1‰ of the mass of the modifier, the molar ratio of polytetrahydrofuran diol, 1,4-diaminoanthraquinone and isophorone diisocyanate is 1:1:3, the amount of dibutyltin dilaurate is 3% of the mass of polytetrahydrofuran diol, and the molecular weight of polytetrahydrofuran diol is 2000.

[0061] The molar ratio of the polyurethane prepolymer, modified monomer and hydroxyethyl methacrylate in step B3 is 10:3:8, the molar ratio of the double bond on the pretreated polyurethane and trichlorosilane is 1:1, and the amount of chloroplatinic acid used is 1‰ of the mass of trichlorosilane.

[0062] Comparative Example 1: Compared with Example 1, no silver powder was added in this comparative example, and the remaining steps were the same.

[0063] Comparative Example 2: Compared with Example 1, in this comparative example, polysiloxane, allyl alcohol, chloroplatinic acid and DMF were mixed, nitrogen was introduced for protection, and the reaction was carried out for 6 hours at a speed of 120 r / min and a temperature of 75°C. The obtained product replaced the modified monomer, and the remaining steps were the same.

[0064] Comparative Example 3: Compared with Example 1, this comparative example uses pretreated resin instead of modified resin, and the remaining steps are the same.

[0065] The conductive coatings prepared in Examples 1-3 and Comparative Examples 1-3 were tested for adhesion in accordance with GB / T 9286-2021, and then baked at 300°C for 30 minutes. The adhesion was then tested, and the conductivity was tested using a four-probe method. The conductivity was then tested again at 300°C for 30 minutes. The conductivity reduction rate was calculated. The test results are shown in Table 1 below.

[0066] Table 1

[0067]

[0068] It can be seen from Table 1 above that the present invention has a good high temperature resistance effect.

[0069] The above content is merely an example and explanation of the concept of the present invention. Those skilled in the art may make various modifications or additions to the described specific embodiments or replace them in a similar manner. As long as they do not deviate from the concept of the invention or exceed the scope defined by the claims, they should all fall within the scope of protection of the present invention.

Claims

1. A method for preparing a conductive coating for a high-temperature resistant lithium battery, characterized in that: The specific steps include: Step A1: lithium dimethylhydrogensilanol and tetrahydrofuran are mixed and stirred, and octamethylcyclotetrasiloxane is added to react to obtain an intermediate. The intermediate, modified polyurethane, and tetrahydrofuran are mixed and reacted to obtain a functionalized polyurethane. Step A2: functionalized polyurethane, modifier, chloroplatinic acid, and DMF are mixed, and nitrogen is introduced to react to obtain a pretreated resin; thioglycolic acid, p-toluenesulfonic acid, triphenyl phosphite, and DMF are uniformly mixed, and nitrogen is introduced to the mixture, and the pretreated resin is added to react to obtain a modified resin; Step A3: Weigh the following raw materials in parts by weight: 80-100 parts of modified resin, 3-5 parts of silver powder, 10-15 parts of carbon black, 10-15 parts of graphene and 150-200 parts of N-methylpyrrolidone, and mix the raw materials evenly at a temperature of 40-60°C to prepare a high-temperature resistant conductive coating for lithium batteries.

2. The method for preparing a conductive coating for a high-temperature resistant lithium battery according to claim 1, wherein: The molar ratio of lithium dimethylhydrogensilanol and octamethylcyclotetrasiloxane in step A1 is 1:3, and the molar ratio of Si-Cl bonds on the intermediate and the modified polyurethane is 1:

1.

3. The method for preparing a conductive coating for a high temperature resistant lithium battery according to claim 1, wherein: The molar ratio of Si-H bonds on the functionalized polyurethane described in step A2 to the modifier is 1:1, and the molar ratio of thioglycolic acid to the hydroxyl groups on the pretreated resin is 1:

1.

4. The method for preparing a conductive coating for a high-temperature resistant lithium battery according to claim 1, wherein: The modified polyurethane is prepared by the following steps: Step B1: Acrylic acid, diethanolamine, p-toluenesulfonic acid, and dimethyl sulfoxide are mixed, nitrogen is introduced to protect the reaction, and the reaction is carried out to prepare a modifier; octamethylcyclotetrasiloxane, tetramethyltetraphenylcyclotetrasiloxane, tetramethylammonium hydroxide, 1,1,3,3-tetramethyldisiloxane, and dichloride are mixed uniformly, nitrogen is introduced to protect the reaction, and polysiloxane is prepared; Step B2: polysiloxane, a modifier, chloroplatinic acid, and DMF are mixed, nitrogen is introduced to protect the mixture, and the mixture is reacted to obtain a modified monomer; polytetrahydrofuran diol, 1,4-diaminoanthraquinone, and acetone are uniformly mixed, nitrogen is introduced to protect the mixture, and isophorone diisocyanate and dibutyltin dilaurate are added with stirring to react to obtain a polyurethane prepolymer; Step B3: The polyurethane prepolymer, modified monomer and DMF are mixed and stirred, and dibutyltin dilaurate is added to react, hydroxyethyl methacrylate is added and reacted to obtain a pretreated polyurethane, and the pretreated polyurethane, trichlorosilane, chloroplatinic acid and DMF are mixed, nitrogen is introduced for protection, and the reaction is carried out to obtain a modified polyurethane.

5. The method for preparing a conductive coating for a high-temperature resistant lithium battery according to claim 4, wherein: The molar ratio of acrylic acid and diethanolamine in step B1 is 1:1, and the usage ratio of octamethylcyclotetrasiloxane, tetramethyltetraphenylcyclotetrasiloxane, tetramethylammonium hydroxide, 1,1,3,3-tetramethyldisiloxane and dithionyl chloride is 3.5 mol:1.3 mol:6 mol:4 mol:8 L.

6. The method for preparing a conductive coating for a high-temperature resistant lithium battery according to claim 4, wherein: The molar ratio of the polysiloxane and the modifier in step B2 is 1:2, and the molar ratio of polytetrahydrofuran diol, 1,4-diaminoanthraquinone and isophorone diisocyanate is 1:1:

3.

7. The method for preparing a conductive coating for a high-temperature resistant lithium battery according to claim 4, wherein: The molar ratio of the polyurethane prepolymer, modified monomer and hydroxyethyl methacrylate in step B3 is 3n+1:n:2n+2, where n is a natural number greater than 0, and the molar ratio of the double bond on the pretreated polyurethane to trichlorosilane is 1:

1.

8. A conductive coating for high temperature resistant lithium batteries, characterized by: Prepared according to any one of claims 1 to 7.

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