High-Performance Supercapacitors Based on Graphitic Nanofibers/Nickel Sulfide Composite Electrodes

Abstract

Fossil fuel depletion, environmental pollution, and global warming have attracted interest in developing green and replaceable energy storage devices. Among various energy storage devices, supercapacitors (SCs) have been widely recognized in a wide range of applications in energy storage over the past decade, such as electric vehicles, mobile electronic devices, large industrial equipment, memory backup systems, and military devices. It is due to their unique properties including high power capability, long cycle lifetime, and fast charge/discharge rate. In this work, nickel sulfide (Ni 3 S 2 ) nanosheets were growth on the surface of graphitic-nanofibres (GNFs) by using pulse-reversal (PR) electrodeposition method. Compared to the pristine Ni 3 S 2 electrode with discharged capacitance of 461 F g-1, the GNFs@ Ni 3 S 2 electrode revealed a higher capacitance of 635 F g -1 at the same charge-discharge current density of 0.5 mA cm -2 . The GNFs@ Ni 3 S 2 electrode still retained 79% of the capacitance at 0.5 mA cm -2 when it was charged/discharged at 4 mAcm -2 . Furthermore, the GNFs@ Ni 3 S 2 electrode showed great electrochemical stability. For instance, the GNFs@ Ni 3 S 2 electrode displayed 90% of initial capacitance after the consecutive 200 cycles charged/discharged at current density of 0.5 mAcm -2 .