An Amorphous Molybdenum Polysulfide Cathode for Rechargeable Magnesium Batteries

Graphical An amorphous molybdenum polysulfide material is synthesized and used as the cathode for rechargeable magnesium batteries. This electrode provides a high capacity (185 mAh g −1 ) and a good rate performance (50 mAh g −1 at 1000 mA g −1 ). A mechanism study demonstrates that both molybdenum and sulfur undergo redox reactions and contribute to the capacity. 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-MoS x ) is synthesized via a simple one-step solvothermal reaction and used as the cathode material for RMBs. The a-MoS x 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 MoS 2 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-MoS x .