Cation reduction and comproportionation as novel strategies to produce high voltage, halide free, carborane based electrolytes for rechargeable Mg batteries

Here we describe the cation reduction and comproportionation as novel routes to synthesize electrolytes for rechargeable Mg-ion batteries. Reduction of the ammonium cation in [HNMe31+][HCB11H111-] with metallic Mg affords the halide free carborane salt [Mg2+][HCB11H111-](2). Comproportionation of [Mg2+] [HCB11H111-](2) with MgPh2 affords the novel monocationic electrolyte [MgPh1+][HCB11H111-], which reversibly deposits/strips Mg with a remarkable oxidative stability of 4.6 V vs. Mg0/+2.