High Energy Density Asymmetric Supercapacitor Based ZnS/NiCo2S4/Co9S8 Nanotube Composites Materials

Flexible energy storage devices are leading to many researches owing to the huge development prospects, especially the energy storage materials. Recently, ZnS/NiCo2S4/Co9S8 nanotube (ZNCN) is synthesized by adding rod-like ZnO during hydrothermal process, differing from previous reports. The capacitance of ZNCN electrode is 1618.1 F g(-1) at the current density of 1 A g(-1) in 2 m KOH, a 1.2-fold enhancement with respect to the pristine NiCo2S4/Co9S8 (NC) (1348 F g(-1)), a 1.44-fold enhancement with respect to the pristine NiCo2S4 (1127 F g(-1)). ZNCN electrode maintains 77% of the original specific capacitance after 5000 cycles at 15 A g(-1). An asymmetric supercapacitor is assembled using ZNCN as its positive electrode and the hydrated ferric oxide (FeOOH) deposited on the carbon cloth as negative electrode (ZNCN//FeOOH) to demonstrate performance. The as-assembled device can operate in a voltage region of 1.6 V, at a power density of 0.75 kW kg(-1), the energy density reaches 66 Wh kg(-1), when solid-state electrolyte and diaphragm are assembled into a flexible solid-state device, it can successfully light up the LED light. The ZNCN in this study may provide a new material for flexible electronic devices, while providing a new strategy for energy storage applications.