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.