High Energy Density Asymmetric Supercapacitor Based on NiOOH/Ni₃S₂/3D Graphene and Fe₃O₄/Graphene Composite Electrodes

摘要

The application of the composite of Ni₃S₂ nanoparticles and 3D graphene as a novel cathode material for supercapacitors is systematically investigated in this study. It is found that the electrode capacitance increases by up to 111% after the composite electrode is activated by the consecutive cyclic voltammetry scanning in 1?M KOH. Due to the synergistic effect, the capacitance and the diffusion coefficient of electrolyte ions of the activated composite electrode are ca. 3.7 and 6.5 times higher than those of the Ni₃S₂ electrode, respectively. Furthermore, the activated composite electrode exhibits an ultrahigh specific capacitance of 3296?F/g and great cycling stability at a current density of 16?A/g. To obtain the reasonable matching of cathode/anode electrodes, the composite of Fe₃O₄ nanoparticles and chemically reduced graphene oxide (Fe₃O₄/rGO) is synthesized as the anode material. The Fe₃O₄/rGO electrode exhibits the specific capacitance of 661?F/g at 1?A/g and excellent rate capability. More importantly, an asymmetric supercapacitor fabricated by two different composite electrodes can be operated reversibly between 0 and 1.6?V and obtain a high specific capacitance of 233?F/g at 5?mV/s, which delivers a maximum energy density of 82.5?Wh/kg at a power density of 930?W/kg.