Solid-state symmetrical supercapacitor based on hierarchical flower-like nickel sulfide with shape-controlled morphological evolution

The development of energy storage materials with high capacity and rapid charging and discharging ability have become the most important and major issues of concern in recent years. In this study, a mesoporous nickel sulfide (NiS) hierarchical framework was synthesized using a simple solvothermal method under optimized experimental conditions, including the amount of sulfur and experimental time, and characterized using a range of spectroscopic and microscopic techniques. The resulting materials were tested further as electrode materials in an electrochemical half-cell assembly and full cell solid-state symmetric assembly cell. The optimized mesoporous nickel sulfide hierarchical showed excellent specific capacitance performance with outstanding cycling stability (∼88.57%) after 5000 consecutive charge discharge cycles. A prototype symmetric supercapacitor device was also assembled using hierarchical flower-like NiS and the measured device performance showed a high capacitance of 11.15 F/g, high energy density of 0.991 Wh/kg at a power density of 132 W/kg, and at power density of 261.11 W/kg at an energy density of 0.329 Wh/kg, and excellent cycling stability (83.8% with 92.9% coulombic efficiency after 2000 cycles at 0.26 A/g). The potential applications of the above device were demonstrated by powering a light emitting diode and commercially available fan for more than 30s discharging time.