Rapid microwave-assisted fabrication of 3D cauliflower-like NiCo2S4 architectures for asymmetric supercapacitors

In this study, 3D cauliflower-like NiCo2S4 architectures have been synthesized through a facile, one-step and template-free microwave method. The cauliflower-like NiCo2S4 materials are made up of 3D microstructures with an average diameter of around 600 nm and each nanostructure is found to be constructed of many intertwined nanoparticles. The NiCo2S4-modified electrode was successfully applied to a pseudocapacitor. The electrochemical performance of the NiCo2S4 material was studied by cyclic voltammetry, galvanostatic charge-discharge and electrical impedance spectroscopy. The 3D cauliflower-like NiCo2S4 materials exhibit a maximum capacitance of 1471 Fg(-1) at 1 Ag-1 and also show remarkable rate capability and prominent cycling stability. To improve the energy density of the supercapacitor, a NiCo2S4-modified electrode and activated carbon-modified electrode were used to assemble an asymmetric capacitor. The asymmetric capacitor demonstrates remarkable properties with a maximum energy density of 44.8 Wh kg(-1) and a maximum power density of 16.0 kW kg(-1). Furthermore, two capacitors assembled together can successfully light up a red light-emitting diode (LED) and last for more than 10 min. The excellent capacitance performance demonstrates that the cauliflower-like NiCo2S4 has potential applications in supercapacitors.