Cu2MoS4 hollow nanocages with fast and stable Mg2+-storage performance

Rechargeable Mg batteries attract an increasing interest for grid energy storage because of the high safety and low cost; however, lack of Mg-intercalation cathodes is seriously hindering their development. In the present study, hollow polyhedral Cu2MoS4 nanocages (CMS-H) are synthesized and investigated as a novel cathode for rechargeable Mg batteries. The layered structure of I-phase Cu2MoS4 acts as ideal host for reversible Mg2+ intercalation/deintercalation, during which the interlayer spacing changes along with valence state change of Cu and Mo elements. CMS-H provides a high reversible capacity (180 mAh g at 50 mA g(-1)) and an excellent rate performance beyond simple Cu2MoS4 nanosheets, demonstrating the privilege of hollow architecture in Mg-storage via accommodating the strain and constructing short-range electron/ion transport pathways. CMS-H exhibits a superior cycleability over 2500 cycles, indicating the stability of I-phase Cu2MoS4 during long-term Mg-intercalation cycling. The present results highlight a new type of hollow Cu2MoS4 material for fast and stable Mg-storage, which is of great significance and provides scientific insights for the development of high-performance cathodes for rechargeable Mg batteries.