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. Mg^0/+2.