Composite current collector containing ptc material and method for manufacturing the same

Abstract

The application discloses a kind of composite current collector containing PTC material and preparation method thereof, it is related to current collector technical field, including polymer base film and copper metal layer on the upper and lower faces of polymer base film.The polymer base film includes the following weight parts raw materials: modified polypropylene 100-110 parts, modified PTC material 20-25 parts, lubricant 1.2-1.4 parts, initiator 0.3-0.5 parts, filler 14-18 parts.Modified polypropylene synthesized is grafted into polypropylene molecular chain with benzotriazole and epoxy group, improve the adhesion of polymer base film and copper metal layer and the corrosion resistance of composite current collector.Modified PTC material synthesized is obtained by loading thiophene ring and DOPO on nano-barium titanate, so that the composite current collector has high ultraviolet resistance, flame retardancy and anti-hot runaway property.The composite current collector containing PTC material of the application has high safety in use in battery, and is worth popularizing.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of current collectors, in particular to a composite current collector containing PTC material and a preparation method thereof. BACKGROUND

[0002] The composite current collector is a sandwich structure of "metal conductive layer-polymer material-metal conductive layer", which is obtained by using PET / PP / PI and other polymer insulating materials as the "sandwich" layer, i.e. the base film, and depositing aluminum or copper on the upper and lower surfaces of the base film. The base film has properties such as insulation and flame retardation, while the metal conductive layer is thin and will melt like a fuse when short-circuited, thus limiting the damage of the battery to the "point break" at the puncture site, effectively forming a "break effect" to prevent continuous large current from causing battery overheating problems and effectively solving the safety problem. Therefore, the performance of the base film is the key to determining the quality of the composite current collector.

[0003] Among the many polymer materials used as base films for composite current collectors, those using polypropylene as the base film are relatively common. However, the polypropylene molecular chain has a small polarity and low surface tension, and the bonding force between the polypropylene and the metal layer with high surface tension is poor. In addition, polypropylene has poor ultraviolet resistance and is easily degraded by ultraviolet radiation, which adversely affects the performance of the base film. To reduce the risk of fire, flame retardants are usually directly added to the base film to improve its flame retardation. However, the directly added flame retardants have poor compatibility with polypropylene and are easily exuded from the base film material, resulting in poor flame retardation of the base film.

[0004] However, for batteries with higher density, if short-circuiting occurs during the puncture or extrusion test, it will be accompanied by a sharp increase in the current, which will increase the risk of thermal runaway and cause safety accidents. In the prior art, materials such as barium titanate with a positive temperature coefficient (PTC) are used. PTC materials exhibit uniform electrical conductivity at the normal operating temperature of the battery, and when the temperature in the battery increases, the electrical resistance of the positive temperature coefficient material suddenly increases to interrupt the flow of current, which can avoid the increased risk of thermal runaway. Nano-barium titanate has the characteristics of small particle size and high surface activity, and is prone to agglomeration, which limits its use in the base film.

[0005] Therefore, it is necessary to develop a suitable modification method to improve the bonding force between the polypropylene base film and the metal, enhance the ultraviolet resistance and flame retardation of the polypropylene base film, and add nano-barium titanate with improved agglomeration to the polypropylene base film. Then, the base film is used in the preparation of a composite current collector to obtain a composite current collector with more excellent performance, which has practical significance. SUMMARY

[0006] In order to solve the technical problems, the application provides a composite current collector containing PTC material and a preparation method thereof.

[0007] The object of the application can be achieved by the following technical solutions.

[0008] The composite current collector containing PTC material comprises a polymer base film and copper metal layers on the upper and lower surfaces of the polymer base film.

[0009] The polymer base film comprises the following raw materials by weight: 100-110 parts of modified polypropylene, 20-25 parts of modified PTC material, 1.2-1.4 parts of lubricant, 0.3-0.5 parts of initiator, and 14-18 parts of filler.

[0010] The lubricant is selected from one of butyl stearate and ethylene bis-stearamide; the initiator is dicumyl peroxide; and the filler is alkali-free glass fiber.

[0011] The preparation of the composite current collector containing PTC material comprises the following steps.

[0012] In step S1, the modified polypropylene, modified PTC material, lubricant, initiator and filler are stirred for 30-40 min, then extruded by a double-screw extruder at 220-240 DEG C, stretched at 115-125 DEG C, heat set at 230-240 DEG C to form a film, then soaked in distilled water at 55-65 DEG C for 10-11 h, and finally dried at 90-100 DEG C for 6-8 h to obtain the polymer base film.

[0013] In step S2, the polymer base film is passed through a copper plating roller along the axial direction of the copper plating roller by using a vacuum evaporation method, and the evaporated copper is plated on both surfaces of the polymer base film to obtain the composite current collector containing PTC material.

[0014] Further, the copper plating roller has a first temperature zone and a second temperature zone, the temperature of the first temperature zone is 45-55 DEG C, and the temperature of the second temperature zone is 15-25 DEG C.

[0015] The preparation of the modified polypropylene comprises the following steps.

[0016] In step A1, the carboxylic acid containing a terminal carbon-carbon double bond is added into DMF, dichlorosulfoxide is added under stirring, and reflux stirring is carried out at 40-50 DEG C for 4-5 h to obtain an acyl chloride product; then the nitro-containing benzotriazole and potassium carbonate are added into dimethyl sulfoxide to obtain a mixed solution 1, the acyl chloride product is added into dimethyl sulfoxide to obtain a mixed solution 2, the mixed solution 2 is added dropwise into the mixed solution 1 under ice water bath, after the dropwise addition is completed, the temperature is increased to 40-45 DEG C, and constant temperature stirring is carried out for 8-10 h, and then reduced pressure distillation is carried out to obtain a nitro product.

[0017] Further, the ratio of the amount of the carboxylic acid containing terminal carbon-carbon double bond, DMF, and dichlorosulfoxide is 0.1-0.12 mol: 50-60 mL: 0.12-0.15 mol, and the carboxylic acid containing terminal carbon-carbon double bond is selected from one of 7-octenoic acid, 5-methylhexyl-2-butenic acid, and 5-hexenoic acid; the ratio of the amount of the nitro-containing benzotriazole, potassium carbonate, and dimethyl sulfoxide is 0.1-0.15 mol: 0.02-0.04 mol: 40-50 mL, and the nitro-containing benzotriazole is selected from one of 6-methyl-7-nitro-1H-benzo[D][1,2,3]triazole and 4-nitro-1H-1,2,3-benzotriazole; the ratio of the amount of the acyl chloride product in the mixed solution 2 and dimethyl sulfoxide is 13-16 g: 30-40 mL; and the ratio of the amount of the mixed solution 1 and the mixed solution 2 is 50-60 mL: 40-50 mL.

[0018] In the reaction process of step A1, the carboxylic acid containing terminal carbon-carbon double bond reacts with dichlorosulfoxide to generate an acyl chloride product; and the acyl chloride product reacts with the secondary amino group of the nitro-containing benzotriazole to generate a nitro product.

[0019] In step A2, the nitro product is added into ethyl acetate, warmed to 45-55°C, and stirred under reflux, then sodium dithionite is added, and stirred under reflux for 1-1.5 h to obtain a primary amine product.

[0020] Further, the ratio of the amount of the nitro product, ethyl acetate, and sodium dithionite is 32-36 g: 100-110 mL: 18-20 g.

[0021] In the reaction process of step A2, the nitro group in the nitro product is reduced to an amino group to obtain a primary amine product.

[0022] In step A3, epichlorohydrin, the primary amine product, and tetrabutylammonium bromide are added into toluene, and stirred under reflux at 100-110°C for 3-4 h, then cooled to room temperature, and sodium hydroxide solution is added, and stirred for 5-6 h to obtain a functional product.

[0023] Further, the ratio of the amount of epichlorohydrin, the primary amine product, tetrabutylammonium bromide, toluene, and sodium hydroxide solution is 19-21 g: 35-39 g: 0.05-0.08 mol: 90-100 mL: 20-25 mL; and the mass fraction of the sodium hydroxide solution is 40-50%.

[0024] In the reaction process of step A3, the amino group of the primary amine product is ring-opened with epichlorohydrin, and then ring-closed to form two epoxy groups to obtain a functional product containing terminal carbon-carbon double bond, benzotriazole, and epoxy group.

[0025] Step A4, functional product, crosslinking agent are added into toluene, after stirring for 10-15 min, polypropylene is added and stirred for 10-15 min, then the reaction bottle is sealed, and then 60 After being taken out after being irradiated by Co γ rays for 8-10 h, the modified polypropylene is obtained after being washed by anhydrous ethanol, extracted by acetone and dried;

[0026] Further, the amount ratio of toluene, functional product, crosslinking agent and polypropylene is 450-500 mL:40-50 g:7-9 g:130-140 g, and the crosslinking agent is divinyl benzene;

[0027] During the reaction of Step A4, the functional product and the polypropylene are grafted under the assistance of the crosslinking agent and the Co γ ray irradiation; 60 Under the assistance of the crosslinking agent and the Co γ ray irradiation, the functional product is grafted with the polypropylene to obtain the modified polypropylene;

[0028] The preparation of the modified PTC material comprises the following steps:

[0029] Step B1, the amino-containing silane coupling agent is added into ethanol and deionized water, and stirred for 8-10 h to obtain a hydrolysis solution; the nano-barium titanate is added into ethanol and ultrasonically dispersed for 20-30 min to obtain a dispersion solution; the hydrolysis solution is added dropwise into the dispersion solution under ultrasonic at a temperature of 60-70 ℃, and stirred and reacted for 10-11 h, and then dried and ground into powder to obtain the nano-barium titanate with amino on the surface;

[0030] Further, the amount ratio of the amino-containing silane coupling agent, ethanol and deionized water in the hydrolysis solution is 10-12 g:60-70 mL:35-45 mL, the amino-containing silane coupling agent is selected from one of KH-550, KH-540, N-methyl-3-aminopropyl trimethoxysilane and N-phenyl-3-aminopropyl trimethoxysilane; the amount ratio of the nano-barium titanate and ethanol in the dispersion solution is 5-6 g:100-120 mL; the amount ratio of the hydrolysis solution and the dispersion solution is 40-50 mL:115-125 mL; and the volume fraction of ethanol is 95%;

[0031] During the reaction of Step B1, the amino-containing silane coupling agent is hydrolyzed to form a chemical bond with the surface of the nano-barium titanate to obtain the nano-barium titanate with amino on the surface;

[0032] Step B2, in a protective gas atmosphere, the formaldehyde containing a thiophene ring is added into acetic anhydride, and then potassium carbonate is added, and stirred and reacted under reflux at 150-170 ℃ for 24-26 h, and then extracted, rotary evaporated and dried to obtain an unsaturated carboxylic acid; in a protective gas atmosphere, DOPO and the unsaturated carboxylic acid are added into DMF, and stirred and reacted at 90-110 ℃ for 8-10 h, and then recrystallized in an ice water bath after being cooled to room temperature, and then filtered under reduced pressure to obtain a carboxyl product;

[0033] Further, the amount ratio of thienyl-containing formaldehyde, acetic anhydride and potassium carbonate is 0.1-0.15 mol: 0.05-0.07 mol: 5-8 mmol, the thienyl-containing formaldehyde is selected from one of 2-thiophene formaldehyde, 2,2-bithiophene-5-acetaldehyde and 5-isobutylthiophene-2-formaldehyde; the amount ratio of DOPO, unsaturated carboxylic acid and DMF is 23-27 g: 16-22 g: 80-100 mL;

[0034] In the reaction process of step B2, the aldehyde group of the thienyl-containing formaldehyde reacts with the acetic anhydride to generate a carboxylic acid containing carbon-carbon double bond, i.e. the unsaturated carboxylic acid; the carbon-carbon double bond of the unsaturated carboxylic acid is added with DOPO to obtain a carboxyl product;

[0035] In step B3, the carboxyl product is added into DMF, dichlorosulfoxide is added under stirring, and reflux stirring reaction is carried out at 45-50 DEG C for 4-5 h to obtain the acyl chloride product 1; the surface amino-containing nano-barium titanate and potassium carbonate are added into dimethyl sulfoxide to obtain a mixed solution a, and the acyl chloride product 1 is added into dimethyl sulfoxide to obtain a mixed solution b; under ice water bath, the mixed solution b is added dropwise into the mixed solution a, after dropwise addition is completed, the temperature is increased to 40-45 DEG C, and constant temperature stirring reaction is carried out for 10-11 h to obtain the modified PTC material;

[0036] Further, the amount ratio of the carboxyl product, DMF and dichlorosulfoxide is 42-46 g: 120-130 mL: 13-15 g; the amount ratio of the surface amino-containing nano-barium titanate, potassium carbonate and dimethyl sulfoxide in the mixed solution a is 8-10 g: 0.01-0.02 mol: 60-70 mL; the amount ratio of the acyl chloride product 1 and dimethyl sulfoxide in the mixed solution b is 45-47 g: 90-100 mL; the amount ratio of the mixed solution a and the mixed solution b is 70-80 mL: 100-110 mL;

[0037] In the reaction process of step B3, the carboxyl product reacts with dichlorosulfoxide to generate the acyl chloride product 1; the amino group of the surface amino-containing nano-barium titanate reacts with the acyl chloride product 1, and the thienyl and DOPO are loaded on the nano-barium titanate to obtain the modified PTC material;

[0038] The present application discloses a composite current collector containing PTC material, which comprises a polymer base film and copper metal layers on the upper and lower surfaces of the polymer base film; the polymer base film is prepared from modified polypropylene, modified PTC material, lubricant, initiator and filler.

[0039] The modified polypropylene is obtained by grafting benzotriazole into polypropylene while introducing epoxy groups; benzotriazole can form stable complexes with the surface of copper metal when the surface of copper metal is in contact with benzotriazole, thereby enhancing the bonding force between the base film prepared from the modified polypropylene and the surface of copper metal; these complexes can form a protective film to prevent corrosive media such as oxygen, water, acid and alkali from approaching, which is also conducive to improving the corrosion resistance of the composite current collector; and the epoxy groups can form strong chemical bonds with the metal surface, thereby further enhancing the adhesion between the polymer base film and the surface of copper metal and making the polymer base film and the surface of copper metal more closely combined; the polymer base film prepared from the modified polypropylene makes up for the defect of insufficient bonding force between the polypropylene base film and the surface of copper metal, and is more conducive to improving the structural stability of the composite current collector.

[0040] The modified PTC material is obtained by grafting and loading thiophene rings and DOPO onto nano-barium titanate; after modification, the agglomeration of nano-barium titanate is improved and the nano-barium titanate is more uniformly dispersed in the matrix; when the temperature in the battery increases, the resistance of the composite current collector can suddenly increase to interrupt the flow of current, which can more effectively improve the thermal runaway phenomenon and improve the thermal runaway prevention performance of the composite current collector; the thiophene ring can effectively absorb ultraviolet energy and convert it into lower-energy heat energy, thereby reducing the aging effect of ultraviolet light on the modified polypropylene; the stability of the thiophene ring loaded on the nano-barium titanate is improved, which can better improve the ultraviolet resistance of the modified composite current collector; the DOPO is loaded on the nano-barium titanate, the compatibility of DOPO with the modified polypropylene is increased and DOPO is less likely to extravasate and fail; when DOPO burns, the surface of the high-molecular polymer is dehydrated and degraded to form a carbon layer, and the phosphorus-containing derivatives generated at the same time cover the surface of the polymer, thereby insulating the transmission of flammable gas and heat and preventing further burning, thereby improving the flame retardance of the polymer base film and avoiding the fire hazard of the battery during use. DETAILED DESCRIPTION

[0041] The technical solutions in the embodiments of the present application will be described below in a clear and complete manner. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0042] Embodiment 1

[0043] A modified polypropylene, the preparation of which comprises the following steps:

[0044] Step Al, 7-octenoic acid was added into DMF, dichlorosulfoxide was added under stirring, the reaction was stirred at 40℃ under reflux for 4h to obtain acyl chloride product; 6-methyl-7-nitro-lH-benzo[D][l,2,3]triazole, potassium carbonate were added into dimethyl sulfoxide to obtain mixture 1, then the acyl chloride product was added into dimethyl sulfoxide to obtain mixture 2, mixture 2 was added dropwise into mixture 1 under ice water bath, after dropwise addition was completed, the temperature was increased to 40℃, the reaction was stirred at constant temperature for 8h, and then was distilled under reduced pressure to obtain nitro product; the amount ratio of 7-octenoic acid, DMF and dichlorosulfoxide was 0.1 mol: 50 mL: 0.12 mol; the amount ratio of 6-methyl-7-nitro-lH-benzo[D][l,2,3]triazole, potassium carbonate and dimethyl sulfoxide in mixture 1 was 0.1 mol: 0.02 mol: 40 mL; the amount ratio of acyl chloride product and dimethyl sulfoxide in mixture 2 was 13 g: 30 mL; the amount ratio of mixture 1 and mixture 2 was 50 mL: 40 mL;

[0045] Step A2, the nitro product was added into ethyl acetate, the temperature was increased to 45℃, and then sodium dithionite was added, the reaction was stirred under reflux for 1h to obtain primary amine product; the amount ratio of nitro product, ethyl acetate and sodium dithionite was 32 g: 100 mL: 18 g;

[0046] Step A3, epichlorohydrin, primary amine product and tetrabutylammonium bromide were added into toluene, the reaction was stirred under reflux at 100℃ for 3h, sodium hydroxide solution was added after the reaction was cooled to room temperature, and then the mixture was stirred for 5h to obtain functional product; the amount ratio of epichlorohydrin, primary amine product, tetrabutylammonium bromide, toluene and sodium hydroxide solution was 19 g: 35 g: 0.05 mol: 90 mL: 20 mL; the mass fraction of sodium hydroxide solution was 40%;

[0047] Step A4, under nitrogen atmosphere, the functional product and divinylbenzene were added into toluene, the mixture was stirred for 10 min, then polypropylene (supplier: Shanghai Eusoh Plastic Co., Ltd.) was added, the mixture was continuously stirred for 10 min, then the reaction bottle was sealed, and the mixture was irradiated by Co γ ray for 8h, then was taken out, washed by anhydrous ethanol, extracted by acetone, and dried to obtain modified polypropylene; the amount ratio of toluene, functional product, divinylbenzene and polypropylene was 450 mL: 40 g: 7 g: 130 g. 60 Co γ ray irradiation for 8h, then was washed by anhydrous ethanol, extracted by acetone, and dried to obtain modified polypropylene; the amount ratio of toluene, functional product, divinylbenzene and polypropylene was 450 mL: 40 g: 7 g: 130 g.

[0048] Example 2

[0049] A modified polypropylene, the preparation comprising the following steps:

[0050] Step Al, 5-methylhexyl-2-butenoic acid was added into DMF, dichlorosulfoxide was added under stirring, the reaction was stirred at 45℃ under reflux for 4.5h to obtain acyl chloride product; 4-nitro-lH-l,2,3-benzotriazole, potassium carbonate were added into dimethyl sulfoxide to obtain mixture 1, then the acyl chloride product was added into dimethyl sulfoxide to obtain mixture 2, mixture 2 was added dropwise into mixture 1 under ice water bath, after dropwise addition was completed, the temperature was increased to 42℃, the reaction was stirred at constant temperature for 9h, then it was distilled under reduced pressure to obtain nitro product; the amount ratio of 5-methylhexyl-2-butenoic acid, DMF, dichlorosulfoxide was 0.11mol:55mL:0.13mol; the amount ratio of 4-nitro-lH-l,2,3-benzotriazole, potassium carbonate, dimethyl sulfoxide in mixture 1 was 0.13mol:0.03mol:45mL; the amount ratio of acyl chloride product, dimethyl sulfoxide in mixture 2 was 14g:35mL; the amount ratio of mixture 1, mixture 2 was 55mL:45mL;

[0051] Step A2, the nitro product was added into ethyl acetate, the temperature was increased to 50℃, the reflux was started, then sodium hydrosulfite was added, the reaction was stirred at reflux for 1.3h to obtain primary amine product; the amount ratio of nitro product, ethyl acetate, sodium hydrosulfite was 34g:105mL:19g;

[0052] Step A3, epichlorohydrin, primary amine product, tetrabutylammonium bromide were added into toluene, the reaction was stirred at reflux at 105℃ for 3.5h, after the temperature was cooled to room temperature, sodium hydroxide solution was added, the reaction was stirred for 5.5h to obtain functional product; the amount ratio of epichlorohydrin, primary amine product, tetrabutylammonium bromide, toluene, sodium hydroxide solution was 20g:37g:0.065mol:95mL:23mL; the mass fraction of sodium hydroxide solution was 45%;

[0053] Step A4, under nitrogen atmosphere, the functional product, divinylbenzene were added into toluene, after stirring for 13min, polypropylene (supplier: Shanghai Eusoh Plastic Co., Ltd.) was added, the reaction was stirred for 13min, then the reaction bottle was sealed, after Co γ irradiation for 9h, it was taken out, then it was washed with anhydrous ethanol, extracted with acetone, dried to obtain modified polypropylene; the amount ratio of toluene, functional product, divinylbenzene, polypropylene was 475mL:45g:8g:135g. 60 Co γ irradiation for 9h, then it was taken out, then it was washed with anhydrous ethanol, extracted with acetone, dried to obtain modified polypropylene; the amount ratio of toluene, functional product, divinylbenzene, polypropylene was 475mL:45g:8g:135g.

[0054] Example 3

[0055] A modified polypropylene, the preparation comprising the following steps:

[0056] Step A1, 5-hexenoic acid was added into DMF, dichlorosulfoxide was added under stirring, the reaction was stirred at 50°C under reflux for 5h to obtain acyl chloride product; 4-nitro-1H-1, 2, 3-benzotriazole, potassium carbonate were added into dimethyl sulfoxide to obtain mixture 1, then acyl chloride product was added into dimethyl sulfoxide to obtain mixture 2, mixture 2 was added dropwise into mixture 1 under ice water bath, after dropwise addition was completed, the temperature was increased to 45°C, the reaction was stirred at constant temperature for 10h, and then distilled under reduced pressure to obtain nitro product; the amount ratio of 5-hexenoic acid, DMF and dichlorosulfoxide was 0.12mol:60mL:0.15mol; the amount ratio of 4-nitro-1H-1, 2, 3-benzotriazole, potassium carbonate and dimethyl sulfoxide in mixture 1 was 0.15mol:0.04mol:50mL; the amount ratio of acyl chloride product and dimethyl sulfoxide in mixture 2 was 16g:40mL; the amount ratio of mixture 1 and mixture 2 was 60mL:50mL;

[0057] Step A2, the nitro product was added into ethyl acetate, the temperature was increased to 55°C, and then reflux stirring was started, sodium hydrosulfite was added, and then the reaction was stirred at reflux for 1.5h to obtain primary amine product; the amount ratio of nitro product, ethyl acetate and sodium hydrosulfite was 36g:110mL:20g;

[0058] Step A3, epichlorohydrin, primary amine product and tetrabutylammonium bromide were added into toluene, the reaction was stirred at 110°C under reflux for 4h, sodium hydroxide solution was added after the reaction was cooled to room temperature, and then the reaction was stirred for 6h to obtain functional product; the amount ratio of epichlorohydrin, primary amine product, tetrabutylammonium bromide, toluene and sodium hydroxide solution was 21g:39g:0.08mol:100mL:25mL; the mass fraction of sodium hydroxide solution was 50%;

[0059] Step A4, under nitrogen atmosphere, the functional product and divinylbenzene were added into toluene, the reaction was stirred for 15min, polypropylene (supplier: Shanghai Ousuo Plastic Co., Ltd.) was added, the reaction was stirred for another 15min, the reaction bottle was sealed, and then the reaction was carried out by 60 After being irradiated by Co γ ray for 10h, the reaction bottle was taken out, and then the modified polypropylene was obtained after being washed by anhydrous ethanol, extracted by acetone and dried; the amount ratio of toluene, functional product, divinylbenzene and polypropylene was 500mL:50g:9g:140g.

[0060] Example 4

[0061] A modified PTC material, the preparation thereof comprises the following steps:

[0062] Step B1, KH-550 was added into ethanol and deionized water, stirred for 8h to obtain a hydrolysis solution; then nano-barium titanate was added into ethanol and ultrasonic dispersed for 20min to obtain a dispersion solution; the hydrolysis solution was added dropwise into the dispersion solution under ultrasonic at 60℃, stirred for 10h, then dried and ground into powder to obtain the nano-barium titanate with amino on the surface; the amount ratio of KH-550, ethanol and deionized water in the hydrolysis solution was 10g:60mL:35mL; the amount ratio of nano-barium titanate and ethanol in the dispersion solution was 5g:100mL; the amount ratio of the hydrolysis solution and the dispersion solution was 40mL:115mL; the volume fraction of ethanol was 95%;

[0063] Step B2, under nitrogen atmosphere, 2-thiophene formaldehyde was added into acetic anhydride, then potassium carbonate was added, stirred and refluxed at 150℃ for 24h, extracted, rotary evaporated, dried to obtain an unsaturated carboxylic acid; under nitrogen atmosphere, DOPO and the unsaturated carboxylic acid were added into DMF, stirred and reacted at 90℃ for 8h, then recrystallized by ice water bath after cooling to room temperature, filtered under reduced pressure to obtain a carboxyl product; the amount ratio of 2-thiophene formaldehyde, acetic anhydride and potassium carbonate was 0.1mol:0.05mol:5mmol; the amount ratio of DOPO, the unsaturated carboxylic acid and DMF was 23g:16g:80mL;

[0064] Step B3, the carboxyl product was added into DMF, dichlorosulfoxide was added under stirring, stirred and refluxed at 45℃ for 4h to obtain acyl chloride product 1; the nano-barium titanate with amino on the surface and potassium carbonate were added into dimethyl sulfoxide to obtain a mixed solution a, then acyl chloride product 1 was added into dimethyl sulfoxide to obtain a mixed solution b, under ice water bath, the mixed solution b was added dropwise into the mixed solution a, after the dropwise addition was completed, the temperature was increased to 40℃, and stirred for 10h to obtain the modified PTC material; the amount ratio of the carboxyl product, DMF and dichlorosulfoxide was 42g:120mL:13g; the amount ratio of the nano-barium titanate with amino on the surface, potassium carbonate and dimethyl sulfoxide in the mixed solution a was 8g:0.01mol:60mL; the amount ratio of acyl chloride product 1 and dimethyl sulfoxide in the mixed solution b was 45g:90mL; the amount ratio of the mixed solution a and the mixed solution b was 70mL:100mL.

[0065] Example 5

[0066] A modified PTC material, the preparation thereof comprises the following steps:

[0067] Step B1, KH-540 was added into ethanol and deionized water, and stirred for 9 hours to obtain a hydrolysis solution; then nano-barium titanate was added into ethanol, and ultrasonic dispersed for 25 minutes to obtain a dispersion solution; the hydrolysis solution was added dropwise into the dispersion solution under ultrasonic at 65°C, and stirred for 10.5 hours to obtain a surface-amino-containing nano-barium titanate; the amount ratio of KH-540, ethanol and deionized water in the hydrolysis solution was 11g:65mL:40mL; the amount ratio of nano-barium titanate and ethanol in the dispersion solution was 5.5g:110mL; the amount ratio of the hydrolysis solution and the dispersion solution was 45mL:120mL; the volume fraction of ethanol was 95%;

[0068] Step B2, under nitrogen atmosphere, 2,2-bithiophene-5-acetaldehyde was added into acetic anhydride, and then potassium carbonate was added, and stirred for 25 hours under reflux at 160°C to obtain an unsaturated carboxylic acid; under nitrogen atmosphere, DOPO and the unsaturated carboxylic acid were added into DMF, and stirred for 9 hours at 100°C, and then recrystallized by ice water bath after cooling to room temperature, and filtered under reduced pressure to obtain a carboxyl product; the amount ratio of 2,2-bithiophene-5-acetaldehyde, acetic anhydride and potassium carbonate was 0.13mol:0.06mol:6.5mmol; the amount ratio of DOPO, the unsaturated carboxylic acid and DMF was 25g:19g:90mL;

[0069] Step B3, the carboxyl product was added into DMF, and dichlorosulfoxide was added under stirring, and stirred for 4.5 hours under reflux at 47°C to obtain an acyl chloride product 1; the surface-amino-containing nano-barium titanate and potassium carbonate were added into dimethyl sulfoxide to obtain a mixed solution a, and then the acyl chloride product 1 was added into dimethyl sulfoxide to obtain a mixed solution b, and the mixed solution b was added dropwise into the mixed solution a under ice water bath, and then the temperature was increased to 42°C, and stirred for 10.5 hours to obtain a modified PTC material; the amount ratio of the carboxyl product, DMF and dichlorosulfoxide was 44g:125mL:14g; the amount ratio of the surface-amino-containing nano-barium titanate, potassium carbonate and dimethyl sulfoxide in the mixed solution a was 9g:0.015mol:65mL; the amount ratio of the acyl chloride product 1 and dimethyl sulfoxide in the mixed solution b was 46g:95mL; the amount ratio of the mixed solution a and the mixed solution b was 75mL:105mL.

[0070] Example 6

[0071] A modified PTC material, the preparation thereof comprising the following steps:

[0072] Step B1, N-methyl-3-aminopropyltrimethoxysilane was added into ethanol and deionized water, stirred for 10 h to obtain a hydrolysis solution; nano-barium titanate was added into ethanol and ultrasonic dispersed for 30 min to obtain a dispersion solution; the hydrolysis solution was added dropwise into the dispersion solution under ultrasonic at 70℃, stirred for 11 h, then dried and ground into powder to obtain the nano-barium titanate with amino on the surface; the amount ratio of N-methyl-3-aminopropyltrimethoxysilane, ethanol and deionized water in the hydrolysis solution was 12 g:70 mL:45 mL; the amount ratio of nano-barium titanate and ethanol in the dispersion solution was 6 g:120 mL; the amount ratio of the hydrolysis solution and the dispersion solution was 50 mL:125 mL; the volume fraction of ethanol was 95%;

[0073] Step B2, 5-isobutylthiophene-2-carboxaldehyde was added into acetic anhydride under nitrogen atmosphere, then potassium carbonate was added, stirred and refluxed at 170℃ for 26 h, extracted, rotary evaporated, dried to obtain an unsaturated carboxylic acid; DOPO and the unsaturated carboxylic acid were added into DMF under nitrogen atmosphere, stirred and reacted at 110℃ for 10 h, cooled to room temperature, recrystallized by ice water bath, and filtered under reduced pressure to obtain a carboxyl product; the amount ratio of 5-isobutylthiophene-2-carboxaldehyde, acetic anhydride and potassium carbonate was 0.15 mol:0.07 mol:8 mmol; the amount ratio of DOPO, the unsaturated carboxylic acid and DMF was 27 g:22 g:100 mL;

[0074] Step B3, the carboxyl product was added into DMF, dichlorosulfoxide was added under stirring, stirred and refluxed at 50℃ for 5 h to obtain acyl chloride product 1; the nano-barium titanate with amino on the surface and potassium carbonate were added into dimethyl sulfoxide to obtain a mixed solution a, acyl chloride product 1 was added into dimethyl sulfoxide to obtain a mixed solution b, mixed solution b was added dropwise into mixed solution a under ice water bath, after the dropwise addition was completed, the temperature was increased to 45℃, and stirred and reacted for 11 h to obtain the modified PTC material; the amount ratio of the carboxyl product, DMF and dichlorosulfoxide was 46 g:130 mL:15 g; the amount ratio of the nano-barium titanate with amino on the surface, potassium carbonate and dimethyl sulfoxide in mixed solution a was 10 g:0.02 mol:70 mL; the amount ratio of acyl chloride product 1 and dimethyl sulfoxide in mixed solution b was 47 g:100 mL; the amount ratio of mixed solution a and mixed solution b was 80 mL:110 mL.

[0075] Example 7

[0076] A composite current collector containing PTC material, comprising a polymer base film and copper metal layers on both sides of the polymer base film; the polymer base film comprises the following raw materials by weight: modified polypropylene 100 parts, modified PTC material 20 parts, lubricant 1.2 parts, initiator 0.3 parts, and filler 14 parts; the lubricant is butyl stearate; the initiator is dicumyl peroxide; and the filler is alkali-free glass fiber (supplier: Hebei Jiegui Mineral Products Co., Ltd.);

[0077] The preparation of the composite current collector containing PTC material comprises the following steps:

[0078] Step S1, after the modified polypropylene obtained in Example 1, the modified PTC material obtained in Example 4, the lubricant, the initiator, and the filler are stirred for 30 min, they are extruded through a double-screw extruder at 220℃, then stretched at 115℃, heat set at 230℃ to form a film, and then soaked in distilled water at 55℃ for 10 h, and finally dried at 90℃ for 6 h to obtain a polymer base film;

[0079] Step S2, the polymer base film is passed through a copper plating roller along the axial direction of the copper plating roller to plate evaporated copper on both sides of the polymer base film by a vacuum evaporation method to obtain a composite current collector containing PTC material; the copper plating roller has a first temperature zone and a second temperature zone, the temperature of the first temperature zone is 45℃, and the temperature of the second temperature zone is 15℃.

[0080] Example 8

[0081] A composite current collector containing PTC material, comprising a polymer base film and copper metal layers on both sides of the polymer base film; the polymer base film comprises the following raw materials by weight: modified polypropylene 105 parts, modified PTC material 23 parts, lubricant 1.3 parts, initiator 0.4 parts, and filler 16 parts; the lubricant is butyl stearate; the initiator is dicumyl peroxide; and the filler is alkali-free glass fiber (supplier: Hebei Jiegui Mineral Products Co., Ltd.);

[0082] The preparation of the composite current collector containing PTC material comprises the following steps:

[0083] Step S1, after the modified polypropylene obtained in Example 2, the modified PTC material obtained in Example 5, the lubricant, the initiator, and the filler are stirred for 35 min, they are extruded through a double-screw extruder at 230℃, then stretched at 120℃, heat set at 235℃ to form a film, and then soaked in distilled water at 60℃ for 10.5 h, and finally dried at 95℃ for 7 h to obtain a polymer base film;

[0084] Step S2, using the method of vacuum evaporation, the polymer base film along the axial direction of the copper plating roller through the copper plating roller, the evaporation of copper plating on both sides of the polymer base film, get the composite current collector containing PTC material; the copper plating roller has a first temperature zone and a second temperature zone, the temperature of the first temperature zone is 50℃, the temperature of the second temperature zone is 20℃.

[0085] Example 9

[0086] A composite current collector containing PTC material, comprising a polymer base film and a copper metal layer on both sides of the polymer base film; the polymer base film comprises the following raw materials by weight: modified polypropylene 110 parts, modified PTC material 25 parts, lubricant 1.4 parts, initiator 0.5 parts, filler 18 parts; the lubricant is butyl stearate; the initiator is dicumyl peroxide; the filler is alkali-free glass fiber (supplier: Hebei Jiegui Mineral Products Co., Ltd.);

[0087] The preparation of the composite current collector containing PTC material comprises the following steps:

[0088] Step S1, the modified polypropylene obtained in Example 3, the modified PTC material obtained in Example 6, the lubricant, the initiator and the filler are stirred for 40 min, then extruded through a twin-screw extruder at 240℃, then stretched at 125℃, heat set at 240℃ to form a film, then soaked in distilled water at 65℃ for 11 h, and finally dried at 100℃ for 8 h to obtain a polymer base film;

[0089] Step S2, using the method of vacuum evaporation, the polymer base film along the axial direction of the copper plating roller through the copper plating roller, the evaporation of copper plating on both sides of the polymer base film, get the composite current collector containing PTC material; the copper plating roller has a first temperature zone and a second temperature zone, the temperature of the first temperature zone is 55℃, the temperature of the second temperature zone is 25℃.

[0090] Comparative Example 1

[0091] Comparing with Example 9, the functional product in the preparation process of the modified polypropylene is replaced by functional product s, without introducing epoxy group, benzotriazole is grafted into polypropylene, and the rest is exactly the same as Example 9, to prepare a composite current collector containing PTC material;

[0092] The preparation process of functional product s is as follows:

[0093] Step A1, 5-hexenoic acid was added into DMF, dichlorosulfoxide was added under stirring, the reaction was stirred at 50°C under reflux for 5h to obtain acyl chloride product e; benzotriazole, potassium carbonate were added into dimethyl sulfoxide to obtain mixture c, then acyl chloride product e was added into dimethyl sulfoxide to obtain mixture d, mixture d was added dropwise into mixture c under ice water bath, after dropwise addition was completed, the temperature was increased to 45°C, and the reaction was stirred for 10h under constant temperature, and then it was distilled under reduced pressure to obtain functional product s; the amount ratio of 5-hexenoic acid, DMF and dichlorosulfoxide was 0.12mol:60mL:0.15mol; the amount ratio of benzotriazole, potassium carbonate and dimethyl sulfoxide was 0.1mol:0.02mol:40mL; the amount ratio of acyl chloride product e and dimethyl sulfoxide was 16g:40mL; the amount ratio of mixture c and mixture d was 60mL:50mL.

[0094] Comparative Example 2

[0095] Comparing with Example 9, the benzotriazole containing nitro group in the preparation process of the modified polypropylene used was replaced by N-methyl-3-nitrobenzylamine, i.e. no benzotriazole was introduced, and the rest was exactly the same as Example 9, to prepare the composite current collector containing PTC material.

[0096] Comparative Example 3

[0097] Comparing with Example 9, the formaldehyde containing thiophene ring in the preparation process of the modified PTC material used was replaced by p-methoxybenzaldehyde, i.e. the thiophene ring was not loaded on the nano-barium titanate, and the rest was exactly the same as Example 9, to prepare the composite current collector containing PTC material.

[0098] Comparative Example 4

[0099] Comparing with Example 9, the carboxyl product in step B3 in the preparation process of the modified PTC material used was replaced by the unsaturated carboxylic acid obtained in step B2, i.e. DOPO was not loaded on the nano-barium titanate, and the rest was exactly the same as Example 9, to prepare the composite current collector containing PTC material.

[0100] Comparative Example 5

[0101] Comparing with Example 9, the modified PTC material used was replaced by nano-barium titanate, and the rest was exactly the same as Example 9, to prepare the composite current collector containing PTC material.

[0102] The composite current collector containing PTC material prepared by the present application was further detected for effect, as follows:

[0103] Adhesion strength: A layer of Permacel P-94 double-sided tape is bonded to a 1mm thick copper foil. A composite current collector is bonded on top of the double-sided tape. A layer of ethylene-acrylic acid copolymer film (DuPont Nurcel 0903, 50μm thick) is then applied over the composite current collector. The adhesion strength is then tested at 1.3×10⁵ N / m. 2 Hot-press at 120℃ for 10s, cool to room temperature, and cut into strips of 150mm×15mm; finally, fix the ethylene-acrylic acid copolymer film of the sample strips to the upper clamp of the tensile testing machine, and fix the rest to the lower clamp. After fixing, peel the two at an angle of 180° and a speed of 100mm / min, and test the peel force, which is the adhesion force between the film and the metal conductive layer.

[0104] Corrosion resistance: A slurry made of active material (graphite), conductive agent (conductive carbon black) and binder (sodium carboxymethyl cellulose) in a mass ratio of 94:3:3 was uniformly coated on the surface of a composite current collector containing PTC material. After drying at 100℃ for 1-1.5h, the battery electrode was obtained. The battery electrode was then immersed in a 1mol / L LiPF6 EC / DMC / DEC mixed solution for 60h. The mass ratio of EC, DMC and DEC in the mixed solution was 1:2:1. Corrosion phenomena were observed.

[0105] Flame retardancy: Flame retardancy was tested in accordance with UL94 standard;

[0106] Tensile strength: For polymer-based films used in composite current collectors, tensile strength tests were conducted according to GB / T13022-1991, and the polymer-based film was placed under ultraviolet radiation with an intensity of 0.89 W / m. 2 After treatment at a temperature of 25℃ and an aging time of 48h, the tensile strength retention rate was measured.

[0107] Thermal runaway resistance: The composite current collector was used in lithium-ion batteries according to conventional techniques in the field. The prepared lithium-ion batteries were subjected to a nail penetration safety test according to the test methods described in GB / T31485-2015, and the temperatures of the corresponding lithium-ion batteries after nail penetration were recorded. The results are recorded in Table 1.

[0108] Table 1: Test Results

[0109]

[0110] According to the data in Table 1, the polymer-based film of the composite current collector containing the PTC material of the application has excellent adhesion with the copper metal layer, the polymer-based film has good ultraviolet aging resistance, the composite current collector has strong corrosion resistance, flame resistance and thermal runaway prevention performance. It can be known from the comparison of Example 9 and Comparative Example 1 that the adhesion of the polymer-based film of the composite current collector prepared by introducing no epoxy group and only grafting benzotriazole into polypropylene to obtain modified polypropylene 1 is decreased. It can be known from the comparison of Example 9 and Comparative Example 2 that the adhesion of the polymer-based film of the composite current collector and the corrosion resistance of the composite current collector are both decreased by introducing no benzotriazole and only introducing epoxy group into polypropylene. It can be known from the comparison of Example 9 and Comparative Example 3 that the ultraviolet aging resistance of the polymer-based film of the composite current collector and the ultraviolet resistance of the composite current collector are both decreased by not loading the thiophene ring on the nano-barium titanate. It can be known from the comparison of Example 9 and Comparative Example 4 that the flame resistance grade of the polymer-based film and the flame resistance of the composite current collector are both decreased by not loading DOPO on the nano-barium titanate. It can be known from the comparison of Example 9 and Comparative Example 5 that the agglomeration phenomenon is not improved, the dispersibility in the polymer-based film is poor, the needle safety is decreased, the thermal runaway prevention performance of the composite current collector is decreased, and the ultraviolet resistance and the flame resistance of the composite current collector are both decreased by not modifying the nano-barium titanate.

[0111] The above is only an example and description of the concept of the application, and those skilled in the art can make various modifications or supplements or use similar ways to replace the described specific embodiments, as long as they do not deviate from the concept of the application or exceed the scope defined by the claims.

Claims

1. A composite current collector comprising a PTC material, characterized by: The application relates to a polymer-based film and a copper metal layer on the upper and lower surfaces of the polymer-based film; the polymer-based film comprises the following raw materials in parts by weight: modified polypropylene 100-110 parts, modified PTC material 20-25 parts, lubricant 1.2-1.4 parts, initiator 0.3-0.5 parts and filler 14-18 parts. The modified polypropylene is prepared by the following steps: Step A1: a carboxylic acid containing a terminal carbon-carbon double bond is added into DMF and stirred to react with dichlorosulfoxide to obtain an acyl chloride product; then nitro-containing benzotriazole and potassium carbonate are added into dimethyl sulfoxide to obtain a mixed solution 1, the acyl chloride product is added into dimethyl sulfoxide to obtain a mixed solution 2, the mixed solution 2 is added dropwise into the mixed solution 1 under an ice water bath, and stirring reaction is carried out to obtain a nitro product; Step A2: the nitro product is added into ethyl acetate and stirred to react with sodium hyposulfite to obtain a primary amine product; Step A3: epoxy chloropropane, the primary amine product and tetrabutylammonium bromide are added into toluene and stirred to react, then sodium hydroxide solution is added, and stirring reaction is carried out to obtain a functional product; Step A4. The functional product, crosslinking agent, and polypropylene are added to toluene under a protective gas atmosphere and stirred at 60°C for 2 hours. 60 Co γ-ray irradiation reaction to obtain modified polypropylene The modified PTC material is prepared by the following steps: Step B1: a silane coupling agent containing an amino group is added into ethanol and deionized water, and stirring is carried out for 8-10 hours to obtain a hydrolysis solution; nano-barium titanate is added into ethanol and ultrasonic dispersion is carried out for 20-30 minutes to obtain a dispersion solution; the hydrolysis solution is added dropwise into the dispersion solution under ultrasonic at a temperature of 60-70 DEG C, stirring reaction is carried out for 10-11 hours, then drying and grinding are carried out to obtain nano-barium titanate with an amino group on the surface; Step B2: in a protective gas atmosphere, formaldehyde containing a thiophene ring is added into acetic anhydride, and potassium carbonate is added, reflux stirring reaction is carried out at 150-170 DEG C for 24-26 hours, extraction, rotary evaporation and drying are carried out to obtain an unsaturated carboxylic acid; in a protective gas atmosphere, DOPO and the unsaturated carboxylic acid are added into DMF, stirring reaction is carried out at 90-110 DEG C for 8-10 hours, after cooling to room temperature, recrystallization is carried out through an ice water bath, and vacuum filtration is carried out to obtain a carboxyl product; Step B3: the carboxyl product is added into DMF, dichlorosulfoxide is added under stirring, reflux stirring reaction is carried out at 45-50 DEG C for 4-5 hours to obtain acyl chloride product 1; the nano-barium titanate with an amino group on the surface and potassium carbonate are added into dimethyl sulfoxide to obtain a mixed solution a, the acyl chloride product 1 is added into dimethyl sulfoxide to obtain a mixed solution b, the mixed solution b is added dropwise into the mixed solution a under an ice water bath, after dropwise addition is completed, the temperature is increased to 40-45 DEG C, and constant temperature stirring reaction is carried out for 10-11 hours to obtain the modified PTC material.

2. The composite current collector containing PTC material according to claim 1, characterized in that: The lubricant is one of butyl stearate and ethylene bis-stearamide, the initiator is dicumyl peroxide, and the filler is alkali-free glass fiber; in step A1, the amount ratio of the carboxylic acid containing a terminal carbon-carbon double bond, DMF and dichlorosulfoxide is 0.1-0.12 mol: 50-60 mL: 0.12-0.15 mol, and the carboxylic acid containing a terminal carbon-carbon double bond is one of 7-octenoic acid, 5-methylhexyl-2-butenic acid and 5-hexenoic acid.

3. The composite current collector containing PTC material according to claim 1, characterized in that: In step A1, the amount ratio of nitro-containing benzotriazole, potassium carbonate, dimethyl sulfoxide in mixture 1 is 0.1-0.15 mol:0.02-0.04 mol:40-50 mL, and the nitro-containing benzotriazole is selected from one of 6-methyl-7-nitro-1H-benzo[D][1,2,3]triazole, 4-nitro-1H-1,2,3-benzotriazole; the amount ratio of acyl chloride product, dimethyl sulfoxide in mixture 2 is 13-16 g:30-40 mL; and the amount ratio of mixture 1, mixture 2 is 50-60 mL:40-50 mL.

4. The composite current collector containing PTC material according to claim 1, wherein: In step A2, the amount ratio of nitro product, ethyl acetate, sodium hydrosulfite is 32-36 g:100-110 mL:18-20 g; in step A4, the amount ratio of toluene, functional product, crosslinking agent, polypropylene is 450-500 mL:40-50 g:7-9 g:130-140 g, and the crosslinking agent is divinyl benzene.

5. The composite current collector containing PTC material according to claim 1, wherein: In step A3, the amount ratio of epichlorohydrin, primary amine product, tetrabutylammonium bromide, toluene, sodium hydroxide solution is 19-21 g:35-39 g:0.05-0.08 mol:90-100 mL:20-25 mL; and the mass fraction of sodium hydroxide solution is 40-50%.

6. The composite current collector containing PTC material according to claim 1, wherein: In step B1, the amount ratio of amino-containing silane coupling agent, ethanol and deionized water in hydrolysis solution is 10-12 g:60-70 mL:35-45 mL, and the amino-containing silane coupling agent is selected from one of KH-550, KH-540, N-methyl-3-aminopropyltrimethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane; the amount ratio of nano barium titanate, ethanol in dispersion solution is 5-6 g:100-120 mL; the amount ratio of hydrolysis solution, dispersion solution is 40-50 mL:115-125 mL; and the volume fraction of ethanol is 95%.

7. The composite current collector containing PTC material according to claim 1, wherein: In step B2, the amount ratio of thienyl-containing formaldehyde, acetic anhydride, potassium carbonate is 0.1-0.15 mol:0.05-0.07 mol:5-8 mmol, and the thienyl-containing formaldehyde is selected from one of 2-thiophene formaldehyde, 2,2-bithiophene-5-acetaldehyde, 5-isobutylthiophene-2-formaldehyde; the amount ratio of DOPO, unsaturated carboxylic acid, DMF is 23-27 g:16-22 g:80-100 mL.

8. The composite current collector containing PTC material according to claim 1, wherein: In step B3, the amount ratio of carboxyl product, DMF, thionyl chloride is 42-46 g:120-130 mL:13-15 g; the amount ratio of surface amino-containing nano barium titanate, potassium carbonate and dimethyl sulfoxide in mixture a is 8-10 g:0.01-0.02 mol:60-70 mL; the amount ratio of acyl chloride product 1, dimethyl sulfoxide in mixture b is 45-47 g:90-100 mL; and the amount ratio of mixture a, mixture b is 70-80 mL:100-110 mL.

9. A method of producing a composite current collector comprising a PTC material according to any one of claims 1 to 8, characterized in that: The method comprises the following steps: Step S1, after the modified polypropylene, modified PTC material, lubricant, initiator and filler are stirred for 30-40 min, they are extruded through a double screw extruder at 220-240℃, then stretched at 115-125℃, heat set at 230-240℃ to form a film, then soaked in distilled water at 55-65℃ for 10-11 h, and finally dried at 90-100℃ for 6-8 h to obtain a polymer-based film; Step S2, using a vacuum evaporation method, the polymer-based film is passed along the axis of the copper plating roller to the copper plating roller, and evaporated copper is plated on both sides of the polymer-based film to obtain a composite current collector containing a PTC material; the copper plating roller has a first temperature zone and a second temperature zone, the temperature of the first temperature zone is 45-55℃, and the temperature of the second temperature zone is 15-25℃.

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