A High-Performance Magnesium Triflate-based Electrolyte for Rechargeable Magnesium Batteries

The quest for a suitable electrolyte formulation is pivotal to the success of rechargeable magnesium batteries. A simple conventional electrolyte having high compatibility with magnesium anode and cathode material is in great demand. Herein, we report a simple yet effective electrolyte formulation, comprising magnesium triflate (Mg(OTf)2) and magnesium chloride in monoglyme, that can enable highly reversible, conditioning-free, and homogeneous magnesium deposition. Galvanostatic Mg plating/stripping demonstrates an average Coulombic efficiency of 99.4% over 1,000 cycles. The cells show excellent performance at current densities up to 3 mA cm−2 and areal capacities up to 5 mAh cm−2. Post mortem analysis unveils the formation of a robust solid electrolyte interphase, which leads to improved kinetics at the magnesium electrode. A prototype Mg battery with Mo6S8 cathode demonstrates stable cycling performance over 100 cycles. This study shows that rational design of Mg(OTf)2-based electrolytes is a promising direction toward the realization of high-performance magnesium batteries.