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CN-121991387-A - Composite current collector base film and preparation method thereof

CN121991387ACN 121991387 ACN121991387 ACN 121991387ACN-121991387-A

Abstract

The invention relates to the field of manufacturing of thin film current collectors, in particular to a composite current collector base film and a preparation method thereof. The preparation method comprises the steps of mixing octamercaptopropyl cage-type polysilsesquioxane with a solvent in protective gas, adding a polymerization inhibitor and a catalyst, heating, dropwise adding glycidyl methacrylate for light-proof constant-temperature reaction, concentrating, precipitating, filtering and drying to obtain cage-type polysilsesquioxane derivatives containing carbon-carbon double bonds and/or epoxy groups, mixing the modifier with matrix resin, a free radical initiator and an antioxidant at a high speed, preparing master batches by reactive melt extrusion and cooling granulation, extruding and casting the master batches into thick sheets, and carrying out biaxial stretching, heat setting and rolling to obtain the composite current collector base film.

Inventors

  • HUANG HAN
  • WANG YONGJUN
  • WANG RUNXIAO
  • ZHUANG ZHI
  • WANG JINZE

Assignees

  • 扬州博恒新能源材料科技有限公司

Dates

Publication Date
20260508
Application Date
20260409

Claims (9)

  1. 1. The preparation method of the composite current collector base film is characterized by comprising the following steps of: Mixing matrix resin, a multifunctional modifier, a free radical initiator and an antioxidant at a high speed to obtain a uniform mixture, adding the uniform mixture into an extruder, performing reactive melt extrusion, cooling and granulating to obtain modified composition master batches; wherein, the preparation of the multifunctional modifier comprises the following steps: Mixing octamercaptopropyl cage-type polysilsesquioxane with a solvent, stirring and dissolving, adding a polymerization inhibitor and a catalyst, heating to 40-60 ℃ in a protective gas atmosphere, dropwise adding glycidyl methacrylate, keeping the temperature away from light, reacting, concentrating the reaction liquid after the reaction is finished, dropwise adding a precipitant to precipitate, carrying out suction filtration, washing and drying to obtain the multifunctional modifier, wherein the multifunctional modifier is a cage-type polysilsesquioxane derivative containing carbon-carbon double bonds and hydroxyl groups in a molecular structure.
  2. 2. The preparation method of the composite current collector base film according to claim 1, wherein the weight ratio of the base resin to the multifunctional modifier to the free radical initiator to the antioxidant is 100 (1.0-10.0) (0.01-0.05) (0.1-0.5).
  3. 3. The method for preparing a composite current collector substrate film according to claim 1, wherein the matrix resin is selected from any one or more of polypropylene, polyethylene terephthalate, polyimide and polyphenylene sulfide; The free radical initiator is selected from any one of 2, 5-dimethyl-2, 5-bis (tert-butylperoxy) hexane, dicumyl peroxide and benzoyl peroxide; The antioxidant is a mixture of hindered phenol antioxidant pentaerythritol tetra [ beta- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionate ] and phosphite antioxidant tri (2, 4-di-tert-butylphenyl) phosphite, and the mass ratio of the hindered phenol antioxidant pentaerythritol tetra [ beta- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionate ] to the phosphite antioxidant tri (2, 4-di-tert-butylphenyl) phosphite is 1 (1-2).
  4. 4. The preparation method of the composite current collector base film according to claim 1, wherein the mass ratio of the octamercaptopropyl cage polysilsesquioxane to the solvent to the polymerization inhibitor to the catalyst to the glycidyl methacrylate is (8-12) (70-100) (0.05-0.15) (0.2-0.5) (4-8).
  5. 5. The preparation method of the composite current collector base film according to claim 1, wherein the solvent is anhydrous tetrahydrofuran, the polymerization inhibitor is hydroquinone, the catalyst is triethylamine, the precipitant is n-hexane, and the shielding gas is nitrogen.
  6. 6. The preparation method of the composite current collector base film according to claim 1, wherein the heating temperature is 40-60 ℃, the light-resistant constant-temperature reaction time is 10-14h, the drying temperature is 25 ℃, and the drying time is 20-28h.
  7. 7. The method for preparing a composite current collector substrate film according to claim 1, wherein the reactive melt extrusion temperature is 180-210 ℃, and the screw rotation speed is 180-220rpm; the biaxial stretching comprises longitudinal stretching and transverse stretching, wherein the longitudinal stretching multiplying power is 4-6 times, the longitudinal stretching temperature is 110-130 ℃, the transverse stretching multiplying power is 5-7 times, and the transverse stretching temperature is 145-165 ℃; The heat setting temperature is 155-175 ℃.
  8. 8. The method for preparing a composite current collector base film according to claim 1, wherein reactive melt extrusion is performed by using a co-rotating twin screw extruder; Extruding the modified composition master batch by adopting a single screw extruder and casting into thick sheets through a T-type die; the temperature of casting into thick plates is 210-230 ℃, and the thickness of the composite current collector base film is 4-5 mu m.
  9. 9. A composite current collector substrate film prepared by the method for preparing a composite current collector substrate film according to any one of claims 1 to 8.

Description

Composite current collector base film and preparation method thereof Technical Field The invention relates to the field of manufacturing of thin film current collectors, in particular to a composite current collector base film and a preparation method thereof. Background The continuous operation of the charge and discharge cycle of the battery brings extremely high requirements for guaranteeing the internal operation safety of the battery, the traditional pure metal foil is easy to peel, and thermal runaway caused by high-temperature thermal shrinkage of the polymer base film is a key factor for causing the safety of the battery to be reduced, so that the high-temperature dimensional stability and the interface binding force of the composite current collector base film are effectively improved, which are important bases for guaranteeing the long-term safe and efficient operation of the battery, and the bonding between the polymer base film and the metal layer is mainly dependent on physical action in the traditional composite current collector technology, so that the interface binding force is poor. In addition, the existing composite current collector is extremely easy to generate phase separation and interface debonding of a metal layer and a matrix under a high-temperature stress field, and the mechanical continuity of a base film can be seriously weakened by the agglomeration effect of nano particles; The invention takes matrix resin and a multifunctional modifier as cores, and a compact physical and chemical dual crosslinking network is built in a matrix through a physical melt blending and chemical reactive extrusion process; according to the invention, through in-situ reactive grafting and free sulfhydryl coordination, the sulfhydryl-containing chain segment is enriched on the surface and metal binding sites are provided, so that the binding force between the composite current collector base film and the metal layer and the high-temperature dimensional stability are improved, and the long-term stable service of the composite current collector is ensured. Disclosure of Invention The invention aims to provide a composite current collector base film and a preparation method thereof, wherein when facing a battery charge-discharge cycle and a high-temperature stress field, the existing modified base film preparation technology is easy to generate phase separation and interface debonding between a metal layer and the base film, and high-molecular base film high-temperature heat shrinkage is easy to cause thermal runaway, and obvious defects exist in the two aspects. Mixing matrix resin, a multifunctional modifier, a free radical initiator and an antioxidant at a high speed to obtain a uniform mixture, adding the uniform mixture into an extruder, performing reactive melt extrusion, cooling and granulating to obtain modified composition master batches; wherein, the preparation of the multifunctional modifier comprises the following steps: Mixing octamercaptopropyl cage-type polysilsesquioxane with a solvent, stirring and dissolving, adding a polymerization inhibitor and a catalyst, heating to 40-60 ℃ in a protective gas atmosphere, dropwise adding glycidyl methacrylate, keeping the temperature away from light, reacting, concentrating the reaction liquid after the reaction is finished, dropwise adding a precipitant to precipitate, carrying out suction filtration, washing and drying to obtain the multifunctional modifier, wherein the multifunctional modifier is a cage-type polysilsesquioxane derivative containing carbon-carbon double bonds and hydroxyl groups in a molecular structure. Optionally, the weight ratio of the matrix resin, the multifunctional modifier, the free radical initiator and the antioxidant is 100 (1.0-10.0) (0.01-0.05) (0.1-0.5). Optionally, the matrix resin is selected from any one or more of polypropylene, polyethylene terephthalate, polyimide, and polyphenylene sulfide; The free radical initiator is selected from any one of 2, 5-dimethyl-2, 5-bis (tert-butylperoxy) hexane, dicumyl peroxide and benzoyl peroxide; The antioxidant is a mixture of hindered phenol antioxidant pentaerythritol tetra [ beta- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionate ] and phosphite antioxidant tri (2, 4-di-tert-butylphenyl) phosphite, and the mass ratio of the hindered phenol antioxidant pentaerythritol tetra [ beta- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionate ] to the phosphite antioxidant tri (2, 4-di-tert-butylphenyl) phosphite is 1 (1-2). Optionally, the mass ratio of the octamercaptopropyl cage polysilsesquioxane, the solvent, the polymerization inhibitor, the catalyst and the glycidyl methacrylate is (8-12): (70-100): (0.05-0.15): (0.2-0.5): (4-8). Optionally, the solvent is anhydrous tetrahydrofuran, the polymerization inhibitor is hydroquinone, the catalyst is triethylamine, the precipitant is n-hexane, and the shielding gas is nitrogen. Optionally, the heating temperature is 40-60 ℃, the light-