NiCo2O4 Hexagonal Nanoplates/Cornstalk-Derived Porous Carbon Composites for High-Performance Supercapacitor Electrodes

Because of the ever-growing concern on fossil energy depletion and ecological environment devastation, the exploitation of biomass-based energy storage devices has been an imperative trend. Here, the one-step carbonization process plus hydrothermal method is proposed to prepare the composite of NiCo2O4 hexagonal nanoplates and three-dimensional porous carbon using cornstalk as the precursor, which can effectively enhance the electrochemical properties of supercapacitors. Compared with the bare cornstalk-derived porous carbon (CSPC) or single NiCo2O4 nanoplates, the as-prepared composite exhibits high specific capacitance and long cycle life, which can be ascribed to the integration of the merits of CSPC with a highly conductive pore-rich structure and NiCo2O4 with high energy density, good redox property, and short ion transport channel. The specific capacitance can reach 959.2 F·g–1 in 6 M KOH electrolyte at a current density of 0.5 A·g–1, and the capacitance retention is 93% at a current density of 20 A·g–1 over more than 5000 cycles, indicating that this composite can be considered as an outstanding electrode material for the development of high-performance supercapacitors.