One Step Synthesis of low Crystalline Nickel Cobalt Sulfide with High Capacitance for Energy Storage Applications
Energy is one of appearing issues to study in recent years because of oil exhausted and environment polluted. Seeking a material with high power density and energy density is urgent to investigate in order to dealing with the energy and environmental problem. Nickel cobalt sulfide is a new pseudo capacitance material to improve the specific capacitance of super capacitor. However, the hydrothermal synthesis of nickel cobalt sulfide (NCS) with the reagent of sodium sulfide is a two-steps process. The process is time consuming and expensive. Herein, a modified process (one-step process) to prepare NCS materials is developed in this study. The comparison of the materials prepared by these two processes is carried out by using the measurements of XRD, SEM, XPS and the electrochemical analyzer. These results show that the NCS prepared by modified process (N1) displays lower crystallinity and nanoflower morphology which is different with NCS made by the two-steps hydrothermal process(N2). The N1 also performs higher specific capacitance of 1712 F g-1 compared with the N2 with capacitance of 904 F g-1 at the same current density of 5 A g-1. This N1 electrode exhibits maximum energy density of 14.9 Wh kg-1 and maximum power density of 3133 W kg-1. The N1 material has great potential to apply in energy storage devices. Keywords - Pseudocapacitor, Nickel Cobalt Sulfide, Hydrothermal Method, Specific Capacitance.