An Amorphous Molybdenum Polysulfide Cathode for Rechargeable Magnesium Batteries

Rechargeable magnesium batteries (RMBs) attract research interest owing to the low cost and high reliability, but the design of cathode materials is the major difficulty of their development. The bivalent magnesium cation suffers from a strong interaction with the anion and is difficult to intercalate into traditional magnesium intercalation cathodes. Herein, an amorphous molybdenum polysulfide (a-MoSx) is synthesized via a simple one-step solvothermal reaction and used as the cathode material for RMBs. The a-MoSx cathode provides a high capacity (185 mAh g(-1)) and a good rate performance (50 mAh g(-1) at 1000 mA g(-1)), which are much superior compared with crystalline MoS2 and demonstrate the privilege of amorphous RMB cathodes. A mechanism study demonstrates both of molybdenum and sulfur undergo redox reactions and contribute to the capacity. Further optimizations indicate low-temperature synthesis would favor the magnesium storage performance of a-MoSx.

Automated summary

Rechargeable magnesium batteries (RMBs) have attracted research interest for their low cost and high reliability, but designing cathode materials is a major challenge. In this study, an amorphous molybdenum polysulfide (a-MoSx) was synthesized and used as the cathode material for RMBs, demonstrating superior capacity and rate performance compared to crystalline MoS2. Mechanism studies showed that both molybdenum and sulfur contribute to the capacity through redox reactions. Further optimizations indicated that low-temperature synthesis improves the magnesium storage performance of a-MoSx.