Low-temperatures synthesis of CuS nanospheres as cathode material for magnesium second batteries

Rechargeable magnesium batteries (RMBs), as one of the most promising candidates for efficient energy storage devices with high energy, power density and high safety, have attracted increasing attention. However, searching for suitable cathode materials with fast diffusion kinetics and exploring their magnesium storage mechanisms remains a great challenge. CuS submicron spheres, made by a facile low-temperature synthesis strategy, were applied as the high-performance cathode for RMBs in this work, which can deliver a high specific capacity of 396 mAh g⁻¹ at 20 mA g⁻¹ and a remarkable rate capacity of 250 mAh g⁻¹ at 1000 mA g⁻¹. The excellent rate performance can be assigned to the nano needle-like particles on the surface of CuS submicron spheres, which can facilitate the diffusion kinetics of Mg²⁺. Further storage mechanism investigations illustrate that the CuS cathodes experience a two-step conversion reaction controlled by diffusion during the electrochemical reaction process. This work could make a contribution to the study of the enhancement of diffusion kinetics of Mg²⁺ and the reaction mechanism of RMBs.