Iron Oxide Nanoneedles Anchored on N-Doped Carbon Nanoarrays as an Electrode for High-Performance Hybrid Supercapacitor

Iron oxides have been widely recognized in the energy storage field, owing to the high theoretical capacitance, low cost, and environmental friendliness. However, the intrinsic poor electrical conductivities have significantly hindered their practical applications. The rational design of the conductive supports is considered an efficient approach to solve the issues. In this work, a three-dimensional composite structure of the Fe2O3 nanoneedles grown on N-doped porous carbon nanoarrays that are derived from a metal-organic framework on carbon cloth (N-C/CC) is designed. The in situ formed N-C/CC nanoarrays substrate not only exhibits desirable conductivity, but also possesses increased diffusion channels and high mechanical flexibility. Thanks to the unique structure, the Fe2O3@N-C/CC composite exhibits a high specific capacitance of 183.3 mF cm-2 at 3 mA cm-2 and excellent cycling stability with 82.7% capacitance retention after 5000 cycles at 5 mA cm-2. Moreover, a quasi-solid-state hybrid supercapacitor is assembled using Fe2O3@N-C/CC as an anode and NiO@N-C/CC as a cathode, and the device delivers a high energy density of 14.1 Wh kg-1 at a power density of 1500 W kg-1. This work demonstrates a different route to develop three-dimensional nanoarray materials for energy storage.