Overcoming passivation in rechargeable magnesium batteries: Artificial solid-electrolyte interface for enhanced anode functionality

Rechargeable magnesium batteries (RMBs) have garnered significant attention in the field of energy storage. However, the use of a traditional electrolyte, Mg(TFSI) 2 /DME, leads to the passivation of the Mg metal anode (MMA), limiting the reversible deposition and dissolution process of Mg 2+ . Consequently, we propose a feasible method to modify the MMA, resulting in the formation of an artificial solid-electrolyte interface (SEI) coating rich in MgBr 2 , MgI 2 and Sb. This modification leads to substantial improvements in the interfacial kinetics and electrochemical properties of MMA, effectively suppressing the passivation reaction and significantly reducing the overpotential from 2 V to 0.3 V. Upon incorporating CuS/VS 4 cathode materials with a 0.15 M SbBr 3 modification, the discharge capacity reached 125 and 191 mAh·g −1 , respectively (compared to the initial capacity of 30 and 98 mAh·g −1 ) after 30 cycles. Similarly, with a 0.8 M SbI 3 modification, the battery exhibited capacities of 220 and 240 mAh·g −1 , respectively. Through a combination of experimental and computational analyses, we confirmed the uniform distribution of Sb, MgBr 2 and MgI 2 on the MMA surface and a substantial decrease in the diffusion barrier of Mg 2+ . This study presents a straightforward and efficient method for constructing an artificial SEI coating.