A facile surface alloy-engineering route to enable robust lithium metal anodes.

Li-rich alloys have been developed as advanced artificial SEI layers to suppress the formation of Li dendrites and parasitic reactions on the Li metal anode. Here, we systematically investigated the role of Li-rich alloys on Li deposition and decomposition of electrolyte molecules by DFT simulations. We found that the alloy surfaces exhibit self-smoothing behavior for suppressing the nucleation of lithium dendrites. This behavior is derived from the surface-localized free electrons (namely, the localized Li-affinity) of the Li-rich alloy SEI surfaces. Furthermore, the electron transfer between the electrolyte molecules and anode surface was efficiently reduced by the Li-rich alloys. The Li-rich alloys with low Li s states at the Fermi level and the high surface work function exhibit low reducibility to the electrolytes. Our findings herein provide a systematical understanding of Li-rich alloy functional layers, which are of great significance for advanced Li metal batteries.