Using a Chloride-Free Magnesium Battery Electrolyte to Form a Robust Anode-Electrolyte Nanointerface.

ABSTRACT

Magnesium bis(hexamethyldisilazide) (Mg(HMDS)2)-based electrolytes are compelling candidates for rechargeable magnesium batteries due to their high compatibility with magnesium metal anode. However, the usual combination of Mg(HMDS)2 with chloride salts limits their practical application due to severe corrosion of cell components and low anodic stability. Herein, we report for the first time, a chloride-free Mg(HMDS)2-based electrolyte in 1,2-dimethoxyethane. By chemically controlling the moisture content using tetrabutylammonium borohydride as a moisture scavenger, the electrolyte demonstrates outstanding electrochemical performance in magnesium plating/stripping, with an average Coulombic efficiency of 98.3% over 150 cycles, and is noncorrosive to cell components. Surface analysis and depth profiling of the magnesium metal anode reveals the formation of a robust solid electrolyte interphase at the anode-electrolyte nanointerface, which allows magnesium plating/stripping to occur reversibly. The electrolyte also demonstrates good compatibility with a copper sulfide nanomaterial cathode, which exhibits a high initial discharge capacity of 261.5 mAh g-1.