One-step microwave-hydrothermal preparation of NiS/rGO hybrid for high-performance symmetric solid-state supercapacitor

The NiS/reduced graphene (rGO) hybrid has recently attracted increasing interest due to its synthetic effect to improve the conductivity and volume expansion of NiS during charge-discharge cycles as well as the capacitive performance of graphene. However, the preparation of high-performance NiS/rGO hybrid electrode material is still a challenging issue due to its complex multi-step preparation process, which causes low reproducibility, long-time and large-energy consuming. Herein, we report a one-step microwave-hydrothermal preparation of NiS/rGO hybrid electrode material. Compared to the conventional multi-step preparation process, the new method is green without using any chemical surfactant and the preparation time is significantly reduced from several days to only 6 h. The as-prepared NiS/rGO hybrid exhibits a low resistance of similar to 0.48 Omega, ultrahigh specific capacitance of 1745.67 F g(-1) at 1 A g(-1) and a high capacity retention of 451.21 F g(-1) at 10 A g(-1) after 3000 consecutive cycles with high reproducibility. The assembled symmetric solid-state supercapacitor (SCC) based on NiS/rGO hybrid electrode material shows a specific capacitance of 14.20 F g(-1), a high energy density of 7.1 Wh kg(-1) and a high power density of 1836 W kg(-1), demonstrating a great potential for the application in the field of energy storage devices.