Fabrication of hybrid supercapacitor device based on NiCo2O4@ZnCo2O4 and the biomass-derived N-doped activated carbon with a honeycomb structure

Highly efficient supercapacitor devices are fabricated with the hybrid nanocomposite material and biomass-derived N-doped activated carbon with tunable morphology, composition and structures. NiCo2O4 materials with different morphologies including spherical, urchin, rod and granular are synthesized using different surfactants. These electrode materials display the maximum specific capacity of 419, 543, 506, and 456 C g(-1) at 1 A g(-1) respectively in 2 M KOH. The optimized urchin-like NiCo2O4 is hybridized with different concentration of ZnCo2O4 nanosheets. The hybridization process significantly increased the specific capacity to 1029 C g(-1) at 1 A g(-1) for NiCo2O4@ZnCo2O4-2 (NZC2). In order to make the hybrid supercapacitor device, honeycomb porous structured N-doped activated carbon is prepared with the Ricinus Communis seed. The prepared material shows an interconnected pore structure with a high nitrogen content and exhibits the maximum specific capacity of 236 C g(-1) at a current density of 1 A g(-1). The hybrid supercapacitor device made from NZC2 and the N-doped activated carbon offers the highest energy density of 101.6 W h kg(-1) with the corresponding power density of 1.62 kW kg(-1). (C) 2020 Elsevier Ltd. All rights reserved.