Construction of NiCo2O4 nanorods into 3D porous ultrathin carbon networks for high-performance asymmetric supercapacitors

Abstract

Rational design of electrode architecture and utilization of distinct components are effective strategies to further enhance the performance of supercapacitors. In this work, a novel hybrid heterostructure consisting of NiCo2O4 nanorods with diameter between 10 nm and 20 nm grown on three-dimensional porous carbon (3D-OPC) is successfully fabricated via a simple direct nucleation on 3D-OPC matrix under hydrothermal conditions. The merits of highly conductive porous carbon and short ion transport channels in NiCo2O4 nanorods together with the synergistic effect between NiCo2O4 and 3D-OPC result in a higher specific capacitance of 1297 F g−1 at 0.5 A g−1 and enhanced rate capability (1253.6 Fg−1 at 5 A g−1) compared with urchin-like NiCo2O4. Moreover, an asymmetric supercapacitor device using hybrid NiCo2O4/3D-OPC and porous carbon as electrodes delivers a high energy density of 29.23 Wh kg−1 at 1.55 kW kg−1, outstanding power density (7.75 kW kg−1 at 27.38 Wh kg−1), and good cycling stability (capacitance retention of 87.6% after 3000 cycles at 1 A g−1), making it as one of the most promising candidates for electrochemical energy storage.