Regulating lithium nucleation and growth by zinc modified current collectors

Abstract

Lithium metal is commonly regarded as the "Holy Grail" anode material for high energy density rechargeable batteries. However, the uncontrollable growth of Li dendrites has posed safety concerns and thus greatly hindered its large-scale application. Here we have modified the surface of a commercial anode current collector, Cu foil, with a thin layer of Zn by a facile electroplating method, in order to regulate the Li nucleation and the following growth processes. Because of the formation of a solid solution buffer layer and Li-Zn alloy phases, the Li nucleation overpotential was dramatically reduced, realizing a uniform Li nucleation and a smooth Li plating morphology. As a result, significantly improved long-term cycling performance with a high Coulombic efficiency was achieved by the lithiophilic Zn coated Cu foil as a current collector. Full cells of Li-LiFePO4 and Li-S using the Li deposited on the Zn modified Cu as the anode, showed increased capacity with low voltage hysteresis and greatly enhanced cycling stability, ascribed to the uniform Li deposition and formation of a stable SEI layer. This work demonstrates the feasibility of employing lithiophilic modified Cu foils as Li metal current collectors for practical applications.