Flower-Shaped Self-Assembled Ni0.5Cu0.5Co2O4 porous architecture: a ternary metal oxide as a High-Performance charge storage electrode material

Abstract

In this work, a wet-chemical followed by thermal annealing strategy is employed to prepare Ni0.5Cu0.5Co2O4 without using any template. The material with flower-like architecture is composed of several nanorods that exhibit good textural properties (surface area: 120 m2 /g, pore volume: 0.35 cc/g) and exposed facets and thus offers numerous electroactive sites for ion diffusion at the vicinity of electrode−electrolyte. The fabricated electrode with Ni0.5Cu0.5Co2O4 exhibits a higher specific capacitance of 367.4 F/g compared to fabricated electrodes using NiCo2O4 (280.3 F/g) and CuCo2O4(133.5 F/g) at the current density of 1 A/g. The material also exhibits high electronic conductivity (low Rct) and impressive cycling stability (89% retention after 5000th cycle). The combination of the synergistic effect of the variable oxidation state of three metal ions, large electroactive surface area, and fast ion diffusion through the porous structure are responsible for this high performance supercapacitive property of the ternary metal oxide. An assembly of four equivalent asymmetric supercapacitors (fabricated using activated carbon as cathode and Ni0.5Cu0.5Co2O4 as anode) connected in series is demonstrated for powering LEDs. The fabricated device has been shown to achieve 53.08 W h kg−1 energy density at the power density of 700.3 W kg−1 and withholding the columbic efficiency of 99.6% after a 5000 cyclic runs at 5 A/g applied current density. Moreover, the output efficiency of the device is better or comparable to most of the Ni- and Co-based asymmetric devices reported earlier.