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 µm ultra-thin electrolytic copper foil with appealing physicochemical properties is prepared, presenting very low Rz (surface roughness) of 1.74 µm 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 µm candidate (205.81 Wh/kg) and the purchased 4.5 µm counterpart (310.48 Wh/kg). Also, decreasing the thickness of commercial copper foil (9 µm) to 4.5 µm demonstrates superiorities in both resources saving and environmental benignity, contributing 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.