Electroless Deposition of Automatically Shedded Thin Copper Foils

Electroless deposition (ELD) is a process widely used for the production of thin metal films, but stripping the films from the substrate remains challenging. Here, we report a low-cost ELD method for the large-scale production of freestanding copper (Cu) foils in a short time of 25-55 min. By atomizing a thin (<100 nm) sacrificial layer of chitosan with weak glycosyl bonds and a high degree of deacetylation on the glass substrate, the chitosan is completely decomposed in the process of Cu-deposition, producing automatically shedded Cu foils with varied thicknesses from 746 nm to 8.33 mu m and high elastic modulus. When used as battery current collectors, the thin Cu foils with enhanced adhesive fastness and contact areas greatly enhance the capacity and rate capability of graphite anodes. Compared with the commercial Cu current collectors, both the battery capacity and energy density are increased by 429.6 and 484.1%, respectively. The reported approach can be extended for fabricating other metal foils such as nickel with properties appealing for applications.