Deep cycling magnesium metal anode enabled by a robust Mg2+-Conducting and electron-insulating interphase

Abstract

Rechargeable magnesium batteries (RMBs) have garnered significant attention due to the abundant natural availability, safety and high volumetric capacity of magnesium (Mg) anode. However, the practical application has been hindered by the pronounced passivation layer and sluggish charge transfer kinetics of Mg anode in commercial conventional electrolytes. Herein, a superb Mg2+-conducting and electron-blocking interphase is in-situ constructed on Mg anode facilely through the spontaneous magnetization reaction with SbBr3 added in cost-effective Mg(TFSI)2 electrolyte. The interphase with high ionic conductivity and electronic resistivity endows Mg anode a stable long-cycling lifespan of 1600 h with a low overpotential (<0.3 V) at 0.5 mA cm−2 and 0.5 mAh cm−2. Benefitting from the deep cycling Mg anode, the Mg||CuS cell delivers an impressive specific capacity 85.2 mAh g−1 over 300 cycles at 1000 mA g−1 with a capacity retention of 82.8 %, as well as the Mg||Mo6S8 cell can be cycled over 500 cycles at 2C. This research provides valuable insight into the interphase construction and presents a feasible way to develop reliable Mg metal anode for high-performance RMBs.