Preparing ultra-thin copper foil as current collector for improving the LIBs performances with reduced carbon footprint

Adopting ultra-thin copper foil as the current collector is one of the most important strategies for improving the gravimetric energy density of lithium-ion batteries (LIBs), however, stumbled by the quality-control of physicochemical properties for ultra-thin foils. Herein, by utilizing combinative additives, the <= 4.5 mu m ultra-thin electrolytic copper foil with appealing physicochemical properties is prepared, presenting very low Rz (surface roughness) of 1.74 mu m and extraordinarily high tensile strength of 435.65 MPa. When being used as the current collector in LIBs, a high gravimetric energy density of 323.19 Wh/kg was achieved, outperforming both the commercial 9 mu m candidate (205.81 Wh/kg) and the purchased 4.5 mu m counterpart (310.48 Wh/kg). Also, decreasing the thickness of commercial copper foil (9 mu m) to 4.5 mu m demonstrates superiorities in both resources saving and environmental benignity, contributing to similar to 32 million tons copper savings in 2030 and 40.6 % elimination in carbon footprint for copper foil preparation. The results herein can provide guidance for quality-controlled preparation of ultra-thin copper foil as well as new insights for resource savings and environmentally friendly manufacturing.