Interfacial engineering of ultra-thin PET/Cu composite foils via etching-grafting modification

Polyethylene terephthalate/copper (PET/Cu) composite foil, which combines lightweight, flexibility, and excellent electrical conductivity, exhibits promising potential for applications in flexible electronics, portable devices, and lithium-ion battery current collectors. However, achieving efficient and stable metallization of the PET substrate with robust interfacial bonding remains a significant challenge. In this study, an ultra-thin PET/Cu composite foil with excellent adhesion and conductivity was prepared through interfacial engineering. The fabrication process involves oxygen plasma etching, functional silane grafting, and electroplating. The prepared PET/Cu composite foil features a copper layer thickness of approximately 1 μm and presents the adhesion strength meeting the ASTM D3359 5B standard. Meanwhile, the foil achieves a minimum resistivity of 2.137 × 10 −8  Ω m. Compared to the pure copper foil, the PET/Cu composite foil exhibits a 44.89 % reduction in areal mass while maintaining exceptional electrochemical performance, revealing substantial prospects as the next-generation anode current collector for lithium-ion batteries.