Improving electrochemical performance of rechargeable magnesium batteries with conditioning-free Mg-Cl complex electrolyte

Electrolyte plays an important role in development of rechargeable magnesium batteries with high energy density and safety. Here, a novel electrolyte is synthesized by the reaction between magnesium powder, AlCl3 and TiCl4 in tetraethylene glycol dimethyl ether. It shows promising electrochemical properties among the current inorganic Mg2+ electrolytes in terms of excellent reversibility and good stability, which can support magnesium deposition and stripping for 1000 cycles with a relatively low overpotential at 0.1 mA/cm2. The non-nucleophilic characteristics makes it well-suited for sulfur cathode of rechargeable Mg batteries. The rechargeable Mg battery coupled with KB/S electrode using copper current collector and Mg anode delivers a high discharge specific capacity of nearly 1000 mAh/g and an impressive prolonged cycle life for 100 cycles, and also shows the excellent rate capability when using lithium bromide as electrolyte additive.