Ternary Mg alloy-based artificial interphase enables high-performance rechargeable magnesium batteries

Abstract

Rechargeable magnesium batteries (RMBs) provide potential advantages over lithium-ion batteries in terms of high volumetric capacity, natural abundance, and high safety. However, the rational design of high-performance magnesium-based metal anodes compatible with conventional electrolytes is a big challenge for the viability of RMBs. In this work, an in-situ formed ternary alloy-based artificial interphase layer on Mg foil as an anode was successfully prepared through a facile and universal electrodeposition strategy. The Mg-Sn-Bi@Mg anode provides high charge transfer dynamics for Mg deposition and constructs a reduced energy barrier for Mg2+ ions desolvation. Thanks to the unique Mg deposition behaviors, the Mg-Sn-Bi@Mg alloy anode demonstrates a low overpotential of 39.4 mV and a long cycle life of >2000 h. The transfer kinetics for RMBs can be largely improved due to the unique alloying reactions. Density functional theory (DFT) calculations demonstrate that the designed ternary alloy-based artificial interphase layer enables faster Mg2+ ion migration than the bare Mg electrode. Full cells with Mo6S8 cathode also show ultra-stable cycling performance over 2400 cycles at 1C in a conventional all-phenyl complex (APC) electrolyte. This facile interface modification strategy sheds light on the development of advanced RMBs and also provides a promising direction for the design of high-performance Mg-based alloy anodes for high-performance RMBs and beyond.