Bifunctional non-nucleophilic electrolyte enables long-life magnesium batteries via elimination of passive film on Mg anode

Magnesium batteries are one of the ideal candidates for next-generation battery systems with high energy density and safety. However, the development of compatible non-nucleophilic electrolytes and the passivation of the Mg anode are the primary obstacles that impede their development. Here, a non-nucleophilic electrolyte is proposed through in-situ reactions between AlCl₃ + InCl₃/TEG (AI-E) electrolyte and Mg anode, which kills two birds with one stone that magnesium salts with the structures of [MgCl·TEG]⁺ and [MgCl·2TEG]⁺ are generated and the passive film on Mg anode is converted into solid electrolyte interphase (SEI). Compared with the Mg(TFSI)₂ electrolyte, the polarization of the Mg anode in the AI-E electrolyte decreases from 2.0 V to 0.08 V for 400 cycles, and the Mg/S battery with the AI-E electrolyte reaches an improved discharge voltage plateau of 1.12 V for 50 cycles. This work expects to provide a one-step method for magnesium salt synthesis and Mg anode passivation.