Superior plating/stripping performance through constructing an artificial interphase layer on metallic Mg anode

Abstract

Rechargeable magnesium batteries (RMBs) have attracted tremendous attention in energy storage applications in term of high abundance, high specific capacity and remarkable safety of metallic magnesium (Mg) anode. However, a serious passivation of Mg anode in the conventional electrolytes leads to extremely poor plating/stripping performance, further hindering its applications. Herein, we propose a convenient method to construct an artificial interphase layer on Mg anode by substitution and alloying reactions between SbCl3 and Mg. This Sb-based artificial interphase layer containing mainly MgCl2 and Mg3Sb2 endows the significantly improved interfacial kinetics and electrochemical performance of Mg anode. The overpotential of Mg plating/stripping in conventional Mg(TFSI)2/DME electrolytes is vastly reduced from over 2 V to 0.25–0.3 V. Combining experiments and calculations, we demonstrate that under the uniform distribution of MgCl2 and Mg3Sb2, an electric field with a favorable potential gradient is formed on the anode surface, which enables swift Mg2+ migration. Meanwhile, this layer can inhibit the decomposition of electrolytes to protect anode. This work provides an in-depth exploration of the artificial solid-electrolyte interface (SEI) construction, and a more achievable and safe path to realize the application of metallic Mg anode in RMBs.