Anionic Se-Substitution toward High-Performance CuS1- x Sex Nanosheet Cathode for Rechargeable Magnesium Batteries.

Rechargeable magnesium batteries (rMBs) are promising as the most ideal further energy storage systems but lack competent cathode materials due to sluggish redox reaction kinetics. Herein, developed is an anionic Se-substitution strategy to improve the rate capability and the cycling stability of 2D CuS1- x Sex nanosheet cathodes through an efficient microwave-induced heating method. The optimized CuS1- x Sex (X = 0.2) nanosheet cathode can exhibit high reversible capacity of 268.5 mAh g-1 at 20 mA g-1 and good cycling stability (140.4 mAh g-1 at 300 mA g-1 upon 100 cycles). Moreover, the CuS1- x Sex (X = 0.2) nanosheet cathode can deliver remarkable rate capability with a reversible capacity of 119.2 mAh g-1 at 500 mA g-1 , much higher than the 21.7 mAh g-1 of pristine CuS nanosheets. The superior electrochemical performance can be ascribed to the enhanced reaction kinetics, enriched cation storage active sites, and shortened ion diffusion pathway of the CuS1- x Sex nanosheet. Therefore, tuning anionic chemical composition demonstrates an effective strategy to develop novel cathode materials for rMBs.

Microwave-Assisted Synthesis of CuS Hierarchical Nanosheets as the Cathode Material for High-Capacity Rechargeable Magnesium Batteries.

Rechargeable magnesium batteries (rMBs) have been recognized as one of most promising next-generation energy storage devices with high energy and power density. However, the development of rMBs has been hampered by the lack of usable cathode materials with high capacity and cycling stability. Herein, we report an ultra-rapid, cost-effective, and scalable synthesis of ultrathin CuS hierarchical nanosheets by a one-step microwave-assisted preparation. Benefiting from the exceptional structural configuration, when used as the cathode material for rMBs at room temperature, the CuS hierarchical nanosheets deliver a high reversible discharge capacity of 300 mA h g-1 at 20 mA g-1, remarkable rate capability (256.5 mA h g-1 at 50 mA g-1 and 237.5 mA h g-1 at 100 mA g-1), and excellent cycling stability (135 mA h g-1 at 200 mA g-1 over 200 cycles). To date, the obtained excellent electrochemical performances are superior to most results ever reported for cathode materials of rMBs.