MgCl₂: The Key Ingredient to Improve Chloride Containing Electrolytes for Rechargeable Magnesium-Ion Batteries

The effect of MgCl 2 on a series of chloride containing magnesium electrolytes was investigated. In the presence of extra MgCl 2 , the electrochemical properties of Grignard reagents (RMgCl, R = Ph, Et, i Pr) were significantly improved, and the advantage of MgCl 2 was further demonstrated in Mg-Mo 6 S 8 rechargeable batteries with improved capacities and much smaller over-potentials. MgCl 2 was then further proven to be a powerful reagent to improve the performance of well-established strong Lewis acid derived magnesium electrolytes including the "all-phenyl" complex (APC) and alkoxide-based magnesium electrolytes. The results suggest that MgCl 2 salt is a very important species to benefit all chloride containing electrolytes for rechargeable magnesium-ion batteries.