▎ 摘　　要

NOVELTY - Swelling-resistant polyester composite film, comprises core layer, surface layer A and surface layer B. The surface layer A and the surface layer B are respectively located on the two side surfaces of the core layer. The raw material of the surface layer A and the surface layer B each independently includes 88-97% polyester material and 3-12% additive. The raw material of the core layer includes 95-99% polyester material and 1-5% additive. The additives in the surface layer A, the surface layer B and the core layer all include a nucleating agent. The content of the nucleating agent in the surface layer A and the surface layer B is higher than the content of the nucleating agent in the core layer, and the mass percentage of the nucleating agent in the surface layer A and the surface layer B in the respective additives is ≮ 50%. USE - The swelling-resistant polyester composite film is useful in a composite current collector of battery pole piece of battery in electronic device (all claimed). ADVANTAGE - The swelling-resistant polyester composite film has high crystallinity, solvent resistance and flexibility, and reduced film breaking rate of the film making process, and ensures stable production of the battery. The composite current collector has improved stability. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are also included for: preparation method of the swelling-resistant polyester composite film, comprising obtaining the polyester chip A by mixing the raw materials of the surface layer A, carrying out melt extrusion and molding chip processing, obtaining the polyester chips B by mixing the raw materials of the core layer, carrying out melt extrusion and forming chips, obtaining the polyester chip C by mixing the raw materials of the surface layer B, carrying out melt extrusion and forming chip processing, crystallizing and drying the polyester chip A, the polyester chip B and the polyester chip C in sequence, placing into different twin-screw extruders respectively, and performing melt extrusion processing to obtain molten polyester materials, performing casting, stretching and heat treatment on the molten polyester material in sequence to obtain a polyester composite film including the surface layer A, the core layer and the surface layer B; composite current collector, comprising a matrix layer and a metal conductive layer, where the metal conductive layer is arranged on at least one surface of the base layer, and the base layer includes the polyester composite film; electrode pole piece, comprising an active material layer located on at least one surface of the composite current collector close to the metal conductive layer; and a battery, comprising a anode sheet and a cathode sheet.