A composite current collector base film with high chemical stability and its preparation method

Abstract

The present invention relates to the field of composite current collector technology, and discloses a composite current collector base film with high chemical stability and a preparation method thereof. The composite current collector base film in this application comprises the following raw materials in parts by weight: 70-90 parts of PET resin, 10-20 parts of PP resin, 8-12 parts of modified silicone, 6-10 parts of reinforcing filler, 0.3-0.6 parts of lubricant, 0.5-1.5 parts of antioxidant, and 1.5-2.5 parts of compatibilizer. The base film is made of PET resin as the main raw material, and PP resin, modified silicone, reinforcing filler and other additives are added. The combined effect of these additives gives the base film excellent chemical stability and improves the poor acid and alkali resistance of traditional PET base films.

Description

Technical Field

[0001] The present invention relates to the technical field of composite current collectors, and in particular to a composite current collector base film with high chemical stability and a preparation method thereof. Background Art

[0002] Composite current collectors are a new type of battery material with a "sandwich" structure, consisting of a polymer layer and a metal conductive layer. They typically consist of a polymer (such as PET, PP, or PI) as the middle layer, with metal conductive layers (such as aluminum or copper) plated on the top and bottom surfaces. The middle layer is typically a film made from PET resin, which is lightweight, corrosion-resistant, and flexible, making it a promising candidate for a matrix material.

[0003] However, pure PET film still faces challenges in its application: insufficient chemical stability. PET itself has a certain tolerance to weak acids, weak bases, and some organic solvents, but under high concentrations of lithium salts (such as LiPF6), ester solvents (such as carbonates), strong acids and bases, and high-temperature cycling conditions, its molecular chains may swell or hydrolyze, leading to a decline in the mechanical properties of the base film and interfacial failure, which in turn leads to a decrease in the conductivity of the current collector and even battery failure. The lack of chemical stability of the PET base film also affects the adhesion between the PET base film and the metal layer, resulting in poor adhesion between the film and the metal layer, which in turn affects battery performance. Therefore, researchers need to develop a composite current collector base film with high chemical stability and high adhesion to meet practical applications. Summary of the Invention

[0004] In order to solve the above technical problems, the present invention provides a composite current collector base film with high chemical stability and a preparation method thereof.

[0005] The purpose of the present invention can be achieved through the following technical solutions:

[0006] A composite current collector base film with high chemical stability, comprising the following raw materials in parts by weight: 70-90 parts of PET resin, 10-20 parts of PP resin, 8-12 parts of modified silicone, 6-10 parts of reinforcing filler, 0.3-0.6 parts of lubricant, 0.5-1.5 parts of antioxidant, and 1.5-2.5 parts of compatibilizer;

[0007] The lubricant is pentaerythritol stearate;

[0008] The antioxidant is one of antioxidant 1010 or antioxidant 168;

[0009] The compatibilizer is maleic anhydride grafted polypropylene;

[0010] The modified silicone is prepared by the following steps:

[0011] Step A1: Stir p-aminophenol, triethylamine, and dichloromethane evenly, transfer to an ice-water bath, add dimethyl chlorophosphate, and stir for 1 hour. Then, heat to 25-35° C. and stir for 12-16 hours. Filter, wash, and dry to obtain a phosphate product.

[0012] Furthermore, in step A1, the molar ratio of p-aminophenol, dimethyl chlorophosphate and triethylamine is 1:1:1;

[0013] Step A2: Epichlorohydrin and methanol are stirred evenly, heated to 65°C in an oil bath, 1-vinylimidazole is added, and stirred for 6 hours. The mixture is distilled under reduced pressure, washed, and the product is collected. The phosphate product, tetrabutylammonium bromide, and DMF (N,N-dimethylformamide) are added to the product, stirred evenly, and heated to 90°C for 4 hours. The mixture is filtered, washed, and dried to obtain the imidazole-phosphate product.

[0014] Furthermore, in step A2, the ratio of epichlorohydrin to 1-vinylimidazole is 10-20 mL:3-6 mL, the molar ratio of the phosphate product to 1-vinylimidazole is 1:1, and the mass of tetrabutylammonium bromide is 0.1-0.3 g;

[0015] Step A3: Under nitrogen conditions, dimethyldimethoxysilane, 2,4,6,8-tetramethylcyclotetrasiloxane, tridecafluorooctyltrimethoxysilane and trifluoromethanesulfonic acid were mixed and stirred for 24 hours, anhydrous sodium bicarbonate was added and stirred for 1 hour, and then anhydrous sodium sulfate was added and stirred for 1 hour. The organic silicon precursor was filtered, rotary evaporated, and dried to collect the organic silicon precursor; the organic silicon precursor was then added dropwise to a mixture containing the imidazole-phosphate product, the KARSTEDT catalyst and toluene, and the mixture was reacted under nitrogen at 90-100° C. for 18-24 hours, rotary evaporated, purified, and dried to obtain the modified organic silicon;

[0016] Furthermore, in step A3, the molar ratio of dimethyldimethoxysilane, 2,4,6,8-tetramethylcyclotetrasiloxane, and tridecafluorooctyltrimethoxysilane in the organosilicon precursor is 1-2:3-6:0.5-1, trifluoromethanesulfonic acid accounts for 0.25wt%-0.35wt% of the total reactants, and anhydrous sodium bicarbonate and anhydrous sodium sulfate account for 20wt%-30wt% and 35wt%-45wt% of the total reactants, respectively;

[0017] Furthermore, in step A3, the molar ratio of the imidazole-phosphate product to 2,4,6,8-tetramethylcyclotetrasiloxane in the modified silicone is 5-10:1, and the KARSTEDT catalyst accounts for 0.001 wt%-0.003 wt% of the total reactants.

[0018] The reinforcing filler is prepared by the following steps:

[0019] Step B1: Ultrasonically disperse chitosan in water, add h-BN (hexagonal boron nitride) and ultrasonically treat for 30 minutes, transfer to a planetary ball mill and ball mill at 450 rpm for 12 hours, let it stand, and filter the upper layer of solution and dry it to obtain pretreated boron nitride nanosheets;

[0020] The surface of boron nitride after wet ball milling contains chitosan with good dispersibility, which can improve the dispersibility of boron nitride;

[0021] Furthermore, in step B1, the ratio of chitosan, water, and h-BN is 3-5 g:50 mL:2-4 g;

[0022] Step B2: Mix pyromellitic anhydride and 4,4'-diaminodiphenyl ether in DMF and stir in an ice-water bath for 30-50 minutes to obtain a PAA precursor solution. Then, add the modified boron nitride nanosheet DMF solution to the PAA precursor solution, raise the temperature to 60°C, and age at this temperature for 45 hours. Then, filter and dry to obtain PAA@boron nitride. Then, heat the PAA@boron nitride at 320-340°C under a nitrogen atmosphere for 1-1.5 hours to obtain a reinforcing filler.

[0023] Furthermore, in step B2, the usage ratio of pyromellitic anhydride, 4,4'-diaminodiphenyl ether and modified boron nitride nanosheets is 0.101-0.203 mol: 0.1-0.2 mol: 200 mL;

[0024] Furthermore, the amount ratio of modified boron nitride nanosheets to DMF in the modified boron nitride nanosheet DMF solution is 5-10 g:200 mL;

[0025] Furthermore, the PAA in step B2 is polyamic acid.

[0026] Using boron nitride with good thermal conductivity as the matrix of the reinforcing filler can improve the thermal conductivity of the base film, enabling the base film to effectively conduct and disperse heat, avoid local overheating, and thus improve the thermal stability of the battery; it can also maintain structural stability in high-temperature environments and reduce mechanical stress caused by thermal expansion or contraction.

[0027] Using polyimide with good acid and alkali resistance to protect boron nitride can reduce the corrosion of acid and alkali on boron nitride, thereby improving the acid resistance of the base film and further improving the chemical stability of the base film.

[0028] A method for preparing a composite current collector base film with high chemical stability comprises the following steps:

[0029] Weigh the raw materials by weight, heat and mix the PET resin, PP resin, modified silicone, reinforcing filler, lubricant, antioxidant and compatibilizer at 230-240° C., transfer the mixture to a twin-screw extruder for extrusion, casting and casting to form a thick base film, and then biaxially stretch the thick base film to form a composite current collector base film;

[0030] Furthermore, the extrusion temperature of the twin-screw extruder is 260-270° C., and the stretching ratio in the biaxial stretching is 3.5-4:1.

[0031] Beneficial effects of the present invention:

[0032] The composite current collector base film in this application is made of PET resin as the main raw material, with the addition of PP resin, modified silicone, reinforcing filler and other additives, which work together to make the base film have excellent chemical stability and improve the poor acid and alkali resistance of traditional PET base film.

[0033] The current collector base film in the present application introduces modified silicone, and utilizes the fluorine element, phosphate group and imidazole structure in the modified silicone to work synergistically to improve the chemical stability of the base film; wherein, the side chain introduces a phosphate group with strong polarity, and the phosphate can improve the adsorption capacity of the base film to the metal layer by chemical bonding or physical adsorption with the metal surface, while also giving the base film certain flame retardant properties; the high bond energy CF bond can also effectively resist the chemical corrosion of the electrolyte, and still has excellent chemical stability under acid and alkaline conditions; the Si-O bond in the main chain has a higher bond energy, and the higher the bond energy, the more stable it is, so that it is difficult to break in high temperature or chemical corrosion environment, and has good stability; in addition, the modified silicone can also physically entangle or chemically react with the resin molecular chain in the base film, thereby improving the density of the base film and making it difficult to be chemically corroded.

[0034] The introduction of the reinforcing filler in this application can form protrusions on the surface of the base film, increasing the roughness of the base film surface, thereby improving the bonding strength between the base film and the metal layer and reducing the shedding of the metal layer due to insufficient adhesion. The reinforcing filler is evenly dispersed in the base film and, through its layered and dense structure, forms a physical barrier within the base film, hindering the penetration of corrosive media. At the same time, the filler itself has high chemical stability and can maintain structural integrity in corrosive environments, thereby improving the chemical stability of the base film. DETAILED DESCRIPTION

[0035] 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.

[0036] Example 1: Modified silicone is prepared by the following steps:

[0037] Step A1: Mix 0.1 mol of p-aminophenol, 0.1 mol of triethylamine, and 100 mL of dichloromethane, transfer to an ice-water bath, add 0.1 mol of dimethyl chlorophosphate, stir for 1 hour, then heat to 25°C and stir for 12 hours, filter, wash, and dry to obtain a phosphate product;

[0038] Step A2, 10 mL of epichlorohydrin and 100 mL of methanol were stirred evenly, heated to 65 ° C under oil bath conditions, 3 mL of 1-vinylimidazole was added and stirred for 6 hours, distilled under reduced pressure, washed, and the product was collected. 0.1 mol of phosphate product, 0.1 g of tetrabutylammonium bromide and 50 mL of DMF were added to the product and stirred evenly, and the temperature was raised to 90 ° C for 4 hours. The mixture was filtered, washed, and dried to obtain the imidazole-phosphate product;

[0039] Step A3. Under nitrogen conditions, 0.1 mol of dimethyldimethoxysilane, 0.3 mol of 2,4,6,8-tetramethylcyclotetrasiloxane, 0.05 mol of tridecafluorooctyltrimethoxysilane and trifluoromethanesulfonic acid were mixed and stirred for 24 hours, anhydrous sodium bicarbonate was added and stirred for 1 hour, and then anhydrous sodium sulfate was added and stirred for 1 hour, filtered, rotary evaporated, and dried to collect the organosilicon precursor; then the organosilicon precursor was added dropwise to a mixture containing 0.9 mol of imidazole-phosphate product, KARSTEDT catalyst and 200 mL of toluene, and reacted under nitrogen at 90° C. for 18 hours, rotary evaporated, purified, and dried to obtain modified organosilicon, wherein trifluoromethanesulfonic acid accounted for 0.25wt% of the total reactants, anhydrous sodium bicarbonate and anhydrous sodium sulfate accounted for 20wt% and 35wt% of the total reactants, respectively, and the KARSTEDT catalyst accounted for 0.001wt% of the total reactants.

[0040] The reinforcing filler is prepared by the following steps:

[0041] Step B1: 3 g of chitosan was ultrasonically dispersed in 50 mL of water, 2 g of h-BN was added, and the mixture was ultrasonically treated for 30 min. The mixture was transferred to a planetary ball mill and ball milled at 450 rpm for 12 h. The mixture was allowed to stand, and the upper layer of the solution was filtered and dried to obtain pretreated boron nitride nanosheets.

[0042] Step B2: 0.101 mol of pyromellitic anhydride and 0.1 mol of 4,4'-diaminodiphenyl ether were mixed in 200 mL of DMF and stirred in an ice-water bath for 30 min to obtain a PAA precursor solution. The modified boron nitride nanosheet DMF solution was then added to the PAA precursor solution, and the mixture was heated to 60°C and aged at a constant temperature for 45 h. The mixture was filtered and dried to obtain PAA@boron nitride. The PAA@boron nitride was then heated at 320°C for 1 h under a nitrogen atmosphere to obtain a reinforced filler.

[0043] Furthermore, the amount ratio of the modified boron nitride nanosheets to DMF in the modified boron nitride nanosheet DMF solution is 5 g:200 mL.

[0044] Example 2: Modified silicone is prepared by the following steps:

[0045] Step A1: 0.1 mol of p-aminophenol, 0.1 mol of triethylamine, and 100 mL of dichloromethane were stirred evenly, transferred to an ice-water bath, 0.1 mol of dimethyl chlorophosphate was added, and stirred for 1 hour. The mixture was then heated to 30° C. and stirred for 14 hours. The mixture was filtered, washed, and dried to obtain a phosphate product.

[0046] Step A2, 15 mL of epichlorohydrin and 100 mL of methanol were stirred evenly, heated to 65 ° C under oil bath conditions, 4.5 mL of 1-vinylimidazole was added and stirred for 6 hours, distilled under reduced pressure, washed, and the product was collected. 0.1 mol of phosphate product, 0.2 g of tetrabutylammonium bromide and 50 mL of DMF were added to the product and stirred evenly, and the temperature was raised to 90 ° C for 4 hours. Filter, wash, and dry to obtain the imidazole-phosphate product;

[0047] Step A3. Under nitrogen conditions, 0.15 mol of dimethyldimethoxysilane, 0.45 mol of 2,4,6,8-tetramethylcyclotetrasiloxane, 0.075 mol of tridecafluorooctyltrimethoxysilane and trifluoromethanesulfonic acid were mixed and stirred for 24 hours, anhydrous sodium bicarbonate was added and stirred for 1 hour, and then anhydrous sodium sulfate was added and stirred for 1 hour. The organic silicon precursor was filtered, rotary evaporated, and dried to collect the organic silicon precursor; the organic silicon precursor was then added dropwise to a mixture containing 1.8 mol of imidazole-phosphate product, KARSTEDT catalyst and 200 mL of toluene, and reacted under nitrogen at 95° C. for 21 hours, rotary evaporated, purified, and dried to obtain modified organic silicon, wherein trifluoromethanesulfonic acid accounted for 0.3 wt% of the total reactants, anhydrous sodium bicarbonate and anhydrous sodium sulfate accounted for 25 wt% and 40 wt% of the total reactants, respectively, and the KARSTEDT catalyst accounted for 0.002 wt% of the total reactants.

[0048] The reinforcing filler is prepared by the following steps:

[0049] Step B1: 4 g of chitosan was ultrasonically dispersed in 50 mL of water, 3 g of h-BN was added, and the mixture was ultrasonically treated for 30 min. The mixture was transferred to a planetary ball mill and ball milled at 450 rpm for 12 h. The mixture was allowed to stand, and the upper layer of the solution was filtered and dried to obtain pretreated boron nitride nanosheets.

[0050] Step B2: 0.151 mol of pyromellitic anhydride and 0.15 mol of 4,4'-diaminodiphenyl ether were mixed in 200 mL of DMF and stirred in an ice-water bath for 40 min to obtain a PAA precursor solution. The modified boron nitride nanosheet DMF solution was then added to the PAA precursor solution, and the mixture was heated to 60°C and aged at a constant temperature for 45 h. The mixture was filtered and dried to obtain PAA@boron nitride. The PAA@boron nitride was then heated at 330°C for 1.2 h under a nitrogen atmosphere to obtain a reinforced filler.

[0051] Furthermore, the amount ratio of the modified boron nitride nanosheets to DMF in the modified boron nitride nanosheet DMF solution is 7.5 g:200 mL.

[0052] Example 3: Modified silicone is prepared by the following steps:

[0053] Step A1: 0.1 mol of p-aminophenol, 0.1 mol of triethylamine, and 100 mL of dichloromethane were stirred evenly, transferred to an ice-water bath, 0.1 mol of dimethyl chlorophosphate was added, and stirred for 1 hour. The mixture was then heated to 35° C. and stirred for 16 hours. The mixture was filtered, washed, and dried to obtain a phosphate product.

[0054] Step A2, 20 mL of epichlorohydrin and 100 mL of methanol were stirred evenly, heated to 65 ° C under oil bath conditions, 6 mL of 1-vinylimidazole was added and stirred for 6 hours, distilled under reduced pressure, washed, and the product was collected. 0.1 mol of phosphate product, 0.3 g of tetrabutylammonium bromide and 50 mL of DMF were added to the product and stirred evenly, and the temperature was raised to 90 ° C for 4 hours. Filter, wash, and dry to obtain the imidazole-phosphate product;

[0055] Step A3. Under nitrogen conditions, 0.2 mol of dimethyldimethoxysilane, 0.6 mol of 2,4,6,8-tetramethylcyclotetrasiloxane, 0.1 mol of tridecafluorooctyltrimethoxysilane and trifluoromethanesulfonic acid were mixed and stirred for 24 hours, anhydrous sodium bicarbonate was added and stirred for 1 hour, and then anhydrous sodium sulfate was added and stirred for 1 hour, filtered, rotary evaporated, and dried to collect the organosilicon precursor; then the organosilicon precursor was added dropwise to a mixture containing 3 mol of imidazole-phosphate product, KARSTEDT catalyst and 200 mL of toluene, and reacted under nitrogen at 100° C. for 24 hours, rotary evaporated, purified, and dried to obtain modified organosilicon, wherein trifluoromethanesulfonic acid accounted for 0.35 wt% of the total reactants, anhydrous sodium bicarbonate and anhydrous sodium sulfate accounted for 30 wt% and 45 wt% of the total reactants, respectively, and the KARSTEDT catalyst accounted for 0.003 wt% of the total reactants.

[0056] The reinforcing filler is prepared by the following steps:

[0057] Step B1: 5 g of chitosan was ultrasonically dispersed in 50 mL of water, 4 g of h-BN was added and ultrasonically treated for 30 min, and the mixture was transferred to a planetary ball mill and ball milled at 450 rpm for 12 h. The mixture was allowed to stand, and the upper layer of the solution was filtered and dried to obtain pretreated boron nitride nanosheets.

[0058] Step B2: 0.203 mol of pyromellitic anhydride and 0.2 mol of 4,4'-diaminodiphenyl ether were mixed in 200 mL of DMF and stirred in an ice-water bath for 50 min to obtain a PAA precursor solution. The modified boron nitride nanosheet DMF solution was then added to the PAA precursor solution, and the mixture was heated to 60°C and aged at a constant temperature for 45 h. The mixture was filtered and dried to obtain PAA@boron nitride. The PAA@boron nitride was then heated at 340°C for 1.5 h under a nitrogen atmosphere to obtain a reinforcing filler.

[0059] Furthermore, the amount ratio of the modified boron nitride nanosheets to DMF in the modified boron nitride nanosheet DMF solution is 10 g:200 mL.

[0060] Example 4: A method for preparing a composite current collector base film with high chemical stability comprises the following steps:

[0061] The raw materials were weighed by weight, and 70 parts of PET resin, 10 parts of PP resin, 8 parts of modified silicone prepared in Example 1, 6 parts of reinforcing filler prepared in Example 1, 0.3 parts of pentaerythritol stearate, 0.5 parts of antioxidant 1010 and 1.5 parts of maleic anhydride grafted polypropylene were heated and mixed at 230°C, and then transferred to a twin-screw extruder and extruded, cast and cast at a temperature of 260°C to form a thick base film, and then the thick base film was biaxially stretched at a stretching ratio of 3.5:1 to form a composite current collector base film.

[0062] Example 5: A method for preparing a composite current collector base film with high chemical stability comprises the following steps:

[0063] The raw materials were weighed by weight, and 80 parts of PET resin, 15 parts of PP resin, 10 parts of modified silicone prepared in Example 2, 8 parts of reinforcing filler prepared in Example 2, 0.5 parts of pentaerythritol stearate, 1 part of antioxidant 168 and 2 parts of maleic anhydride grafted polypropylene were heated and mixed at 235°C, and then transferred to a twin-screw extruder and extruded, cast and cast at a temperature of 265°C to form a thick base film, and then the thick base film was biaxially stretched at a stretching ratio of 4:1 to form a composite current collector base film.

[0064] Example 6: A method for preparing a composite current collector base film with high chemical stability comprises the following steps:

[0065] The raw materials were weighed by weight, and 90 parts of PET resin, 20 parts of PP resin, 12 parts of modified silicone prepared in Example 3, 10 parts of reinforcing filler prepared in Example 3, 0.6 parts of pentaerythritol stearate, 1.5 parts of antioxidant 168 and 2.5 parts of maleic anhydride grafted polypropylene were heated and mixed at 240°C, and then transferred to a twin-screw extruder and extruded, cast and cast at a temperature of 270°C to form a thick base film, and then the thick base film was biaxially stretched at a stretching ratio of 4:1 to form a composite current collector base film.

[0066] Comparative Example 1: This comparative example is a composite current collector base film. The difference from Example 6 is that h-BN is used instead of the reinforcing filler prepared in Example 3, and the rest are the same.

[0067] Comparative Example 2: This comparative example is a composite current collector base film. The difference from Example 6 is that commercially available organic silicon is used instead of the modified organic silicon prepared in Example 3. The rest are the same.

[0068] Comparative Example 3: This comparative example is a composite current collector base film, which differs from Example 6 in that the modified organic silicon prepared in Example 3 and the reinforcing filler prepared in Example 3 are not added, and the rest are the same.

[0069] The composite current collector base films prepared in Examples 4-6 and Comparative Examples 1-3 were subjected to performance tests:

[0070] Tensile performance test: tensile strength test according to ASTM D638-2014;

[0071] Adhesion performance test: Copper was magnetron sputtered onto the composite current collector base film prepared in Examples 4-6 and Comparative Examples 1-3 to form a 0.2 mm copper plating layer on the composite current collector base film. An adhesion / peeling test was performed using 3M tape, and the number of peeling times was recorded.

[0072] Chemical performance test: The composite current collector base film was cut into 10 cm × 10 cm samples and immersed in 5 wt% HCl solution, 5 wt% NaOH solution, and electrolyte at 25°C for 7 days. The samples were then removed, cleaned, and dried. The mass before and after samples were compared, and the mass loss rate was calculated. The electrolyte was a mixture of ethylene carbonate, diethyl carbonate, and methyl ethyl carbonate in a mass ratio of 1:2:1.

[0073] Thermal stability test: The composite current collector base film was tested for thermal shrinkage according to ASTM D1204. The smaller the value, the higher the thermal stability. The test was based on the thermal shrinkage of the film after being placed at 150°C for 30 minutes. The test results are shown in Table 1:

[0074] Table 1: Performance test results

[0075]

[0076] As can be seen from Table 1, the composite current collector base film prepared in the present invention has excellent tensile strength, adhesion, acid and alkali resistance, electrolyte resistance and thermal stability. Therefore, it has a good application prospect as a base film for current collectors.

[0077] 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 scope defined by the concept of the invention, they should all fall within the scope of protection of the present invention.

Claims

1. A composite current collector base film with high chemical stability, characterized in that: The invention comprises the following raw materials in parts by weight: 70-90 parts of PET resin, 10-20 parts of PP resin, 8-12 parts of modified silicone, 6-10 parts of reinforcing filler, 0.3-0.6 parts of lubricant, 0.5-1.5 parts of antioxidant, and 1.5-2.5 parts of compatibilizer; The lubricant is pentaerythritol stearate, the antioxidant is one of antioxidant 1010 or antioxidant 168, and the compatibilizer is maleic anhydride grafted polypropylene; The modified organosilicon is prepared by a hydrosilylation reaction of an organosilicon precursor and an imidazole-phosphate product, wherein the organosilicon precursor is prepared by the reaction of dimethyldimethoxysilane, 2,4,6,8-tetramethylcyclotetrasiloxane and tridecafluorooctyltrimethoxysilane, and the imidazole-phosphate product is prepared by the reaction of epichlorohydrin, 1-vinylimidazole and a phosphate product, and the phosphate product is prepared by the reaction of p-aminophenol and dimethyl chlorophosphate; The reinforcing filler is prepared by reacting pyromellitic acid, 4,4'-diaminodiphenyl ether and pre-treated boron nitride nanosheets, and the pre-treated boron nitride nanosheets are prepared by wet ball milling h-BN and chitosan.

2. The high chemical stability composite current collector base film according to claim 1, characterized in that: The modified silicone is prepared by the following steps: Step A1: Stir p-aminophenol, triethylamine, and dichloromethane evenly, transfer to an ice-water bath, add dimethyl chlorophosphate, and stir for 1 hour. Then, heat to 25-35° C. and stir for 12-16 hours. Filter, wash, and dry to obtain a phosphate product. Step A2: Epichlorohydrin and methanol were stirred evenly, heated to 65°C in an oil bath, 1-vinylimidazole was added, and stirred for 6 hours. The mixture was distilled under reduced pressure, washed, and the product was collected. The phosphate product, tetrabutylammonium bromide, and DMF were added to the product, stirred evenly, and heated to 90°C for 4 hours. The mixture was filtered, washed, and dried to obtain the imidazole-phosphate product. Step A3. Under nitrogen conditions, dimethyldimethoxysilane, 2,4,6,8-tetramethylcyclotetrasiloxane, tridecafluorooctyltrimethoxysilane and trifluoromethanesulfonic acid were mixed and stirred for 24 hours, anhydrous sodium bicarbonate was added and stirred for 1 hour, and then anhydrous sodium sulfate was added and stirred for 1 hour. The organic silicon precursor was filtered, rotary evaporated, and dried to collect the organic silicon precursor; the organic silicon precursor was then added dropwise to a mixture containing the imidazole-phosphate product, KARSTEDT catalyst and toluene, and reacted under nitrogen at 90-100° C. for 18-24 hours, rotary evaporated, purified, and dried to obtain the modified organic silicon.

3. The high chemical stability composite current collector base film according to claim 2, characterized in that: The molar ratio of p-aminophenol, dimethyl chlorophosphate and triethylamine in step A1 is 1:1:

1.

4. The high chemical stability composite current collector base film according to claim 2, characterized in that: In step A2, the usage ratio of epichlorohydrin and 1-vinylimidazole is 10-20 mL:3-6 mL, the molar ratio of the phosphate product and 1-vinylimidazole is 1:1, and the mass of tetrabutylammonium bromide is 0.1-0.3 g.

5. The high chemical stability composite current collector base film according to claim 2, characterized in that: In step A3, the molar ratio of dimethyldimethoxysilane, 2,4,6,8-tetramethylcyclotetrasiloxane, and tridecafluorooctyltrimethoxysilane in the organosilicon precursor is 1-2:3-6:0.5-1, trifluoromethanesulfonic acid accounts for 0.25wt%-0.35wt% of the total reactants, and anhydrous sodium bicarbonate and anhydrous sodium sulfate account for 20wt%-30wt% and 35wt%-45wt% of the total reactants, respectively.

6. The high chemical stability composite current collector base film according to claim 2, characterized in that: In step A3, the molar ratio of the imidazole-phosphate product to 2,4,6,8-tetramethylcyclotetrasiloxane in the modified organosilicon is 5-10:1, and the KARSTEDT catalyst accounts for 0.001 wt%-0.003 wt% of the total reactants.

7. The high chemical stability composite current collector base film according to claim 1, characterized in that: The reinforcing filler is prepared by the following steps: Step B1, ultrasonically disperse chitosan in water, add h-BN and ultrasonically treat for 30 minutes, transfer to a planetary ball mill and ball mill at 450 rpm for 12 hours, let it stand, take the upper layer solution by suction filtration, and dry to obtain pre-treated boron nitride nanosheets; Step B2: Mix pyromellitic anhydride and 4,4'-diaminodiphenyl ether in DMF and stir in an ice-water bath for 30-50 minutes to obtain a PAA precursor solution. Then, add the modified boron nitride nanosheet DMF solution to the PAA precursor solution, raise the temperature to 60°C and age at a constant temperature for 45 hours, filter, and dry to obtain PAA@boron nitride. Then, heat the PAA@boron nitride at 320-340°C under a nitrogen atmosphere for 1-1.5 hours to obtain a reinforcing filler.

8. The high chemical stability composite current collector base film according to claim 7, characterized in that: The usage ratio of chitosan, water and h-BN in step B1 is 3-5 g:50 mL:2-4 g.

9. The high chemical stability composite current collector base film according to claim 7, characterized in that: In step B2, the usage ratio of pyromellitic anhydride, 4,4'-diaminodiphenyl ether and modified boron nitride nanosheets is 0.101-0.203 mol:0.1-0.2 mol:200 mL, and the usage ratio of modified boron nitride nanosheets and DMF in the modified boron nitride nanosheet DMF solution is 5-10 g:200 mL.

10. A method for preparing the composite current collector base film with high chemical stability according to any one of claims 1 to 9, characterized in that: The following steps are involved: The raw materials are weighed by weight, and the PET resin, PP resin, modified silicone, reinforcing filler, lubricant, antioxidant and compatibilizer are heated and mixed at 230-240°C, and then transferred to a twin-screw extruder for extrusion, casting and casting to form a thick base film. The thick base film is then biaxially stretched to form a composite current collector base film. The extrusion temperature of the twin-screw extruder is 260-270°C, and the stretching ratio in the biaxial stretching is 3.5-4:1.

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