PNNL

Abstract

Lithium-magnesium (Li-Mg) alloy has been considered as a potential alternative anode for high energy density rechargeable Li metal batteries. However, the optimum content of Mg in Li-Mg alloy and the mechanism of the improved performance are not well understood. Herein, density functional theory calculation is used to investigate the effect of Mg amount in Li-Mg alloy anode. The Li-Mg alloy with about 5 wt.% Mg (Li-Mg5) has the lowest absorption energy of Li. Therefore, all the surface area can be “controlled” by Mg atom, leading to the smoothly continuous deposition of Li on the surface around the Mg center. Electrochemical experiments further demonstrate that Li-Mg5 exhibits the best cycling stability in Li metal batteries with high-voltage, high-loading cathode and lean electrolyte, and it also leads to smooth, compact and less corrosion layer on the surface. Both theoretical simulations and experimental results prove that Li-Mg5 has optimum Mg content and gives best battery cycling performance.