Competitive Current Modes for Tunable Ni-Sn Electrodeposition and Their Lithiation/Delithiation Properties

Li-ion battery (LIB) anodes with graded composition have the potential to relax interfacial stress and better accommodate the internal stress buildup within the anode during battery operation. A one-dimensional numerical model was developed, where the balance between two competitive current modes (electrokinetic reaction-limited current and diffusion-limited current) defines the deposit composition. The model indicated that the composition of a binary alloy deposit can be varied with overpotential, by decreasing the relative concentration of the more noble element in the plating bath. Indeed, when Ni-Sn alloy was electrodeposited from a Ni 2+ :Sn 2+ =50:1 bath, the fraction of Sn in the deposit decreased, from 0.47 to 0.13, with increasing current density. Under this plating condition, Ni-Sn deposits were prepared with uniform, discretized and gradient changes in the deposition current density. Cyclic voltammetry of these samples demonstrated both reversible and irreversible reactions with Li-ion, offering a promising premise for LIB application.