Facile Preparation of CuCo S /Cu S Nanocomposites as High-Performance Cathode Materials for Rechargeable Magnesium Batteries*.

Rechargeable magnesium batteries (RMBs) have been considered a promising energy-storage device due to their high energy density and high safety, but they still suffer from a lack of high-rate performance and cycle performance of the cathode. Nanosized CuCo S /Cu S composites have been synthesized for the first time by a facile solvothermal method. Herein, the magnesium ion storage behavior when applied in the cathode for RMBs is discussed. Electrochemical results demonstrated that the CuCo S /Cu S composites exhibit a high initial discharge capacity of 256 mAh g at 10 mA g and 123 mAh g at 300 mA g at room temperature and an outstanding long-term cyclic stability over 300 cycles at 300 mA g . Furthermore, the electrochemical storage mechanism demonstrated that the storage process of magnesium ion in the CuCo S /Cu S cathode is mainly driven by strong pseudocapacitive effects.