Nanoribbon-Like Nico2o4/Reduced Graphene Oxide Nanocomposite for High-Performance Hybrid Supercapacitor
Nanoribbon-like NiCo2O4/reduced graphene oxide (RGO) nanocomposites are in situ prepared by an oxalate-assisted hydrothermal method. The various RGO contents (10, 20, and 30 wt.%) were added during oxalate precipitation. The plate-like shape of oxalate precipitates was thermally decomposed into the nanoribbon-like morphology in which the NiCo2O4 nanoparticles were aligned in one direction. There was a network of pores between nanoparticles (~21-14 nm) because caused by exhausting a large volume of gases during calcination at 450 °C. The specific capacitance increases from 820 to 1486 F g-1 at 1 A g-1 with the amounts of RGO up to 30 wt. %. Furthermore, the NiCo2O4/RGO nanocomposites exhibit higher rate capability in comparison with the pristine NiCo2O4 nanoparticles. The NiCo2O4/30 wt. % RGO//active carbon (AC) hybrid capacitor has a high energy density of 61 Wh kg-1 at the current density of 1 A g-1 and excellent cycling stability of 92% at 3 A g-1 after 5000 cycles