Microwave-induced phase engineering of copper sulfide nanosheets for rechargeable magnesium batteries

Phase controlling in transition metal dichalcogenides has been considered as a powerful route to regulate their chemical and electronic property for energy-related application yet is still subject to limited efficient fabrication method. We herein report a microwave-assisted strategy to synthesize Cu_xS nanosheets with tunable phases as high-performance cathode materials for rechargeable magnesium batteries. By precisely controlling the microwave irradiation time, the ultrathin two-dimensional Cu_xS nanosheets with graphene-like morphologies can be selectively prepared. The electrochemical measurements show that the specific capacities of different Cu_xS nanosheets strongly depend on their crystallographic structure and comply with a decreasing tendency of Cu_1.7S > CuS > Cu_1.9S. The multiphase Cu_1.7S nanosheets delivers a capacity of 153.0 mAh g ^{− 1} at 300 mA g ^{− 1}, significantly higher than that 100.8 and 84.8 mAh g ^{− 1} of CuS and Cu_1.9S counterparts. Moreover, Cu_1.7S nanosheets display an excellent rate capability at various high current densities. Our work found that tuning the phase composition of Cu_xS could improve its electrochemical performances for rechargeable magnesium batteries. In addition, we offer a facile strategy to fabricate multiphase two-dimensional metal sulfide materials with great potential applications for energy devices.