Rational design of hierarchical FeCo2O4 nanosheets@NiO nanowhiskers core-shell heterostructure as binder-free electrodes for efficient pseudocapacitors

Hierarchical core-shell nanoarchitectures have triggered significant technological and scientific interests because of their remarkable versatility in nanoscale electronics and energy storage systems. Meanwhile, designing and fabricating the heterostructure electrode materials by employing effective interface modification could acquire prominent electrochemical performance for supercapacitors. In this study, we reported that FeCo2O4 nanosheets were first synthesized on Ni foam, and then the novel microstructure of NiO nanowhiskers was covered on FeCo2O4 by surface modification. The FeCo2O4 NSs@NiO NWs composite with hierarchical and core-shell structure presented ultrahigh specific capacitance of 4746.2 F g(-1) at the current density of 1 A g(-1), and the remarkable capacitance retention was 88.9% after 8000 cycles at 5 A g(-1). Meanwhile, the asymmetric supercapacitors (FeCo2O4 NSs@NiONWs//AC) exhibited excellent energy density of 60.6 Wh kg(-1) and remarkable power density of 30 kW kg(-1), which could efficiently light up 23 red LED (1.8 V). The device also displayed prominent cyclic stability with 130.8% capacitance retention after 8000 cycles at a current density of 5 A g(-1). This work presented a new method to accomplish a controllable synthesis of hierarchical core-shell heterostructure as electrode materials for high-performance electrochemical energy storage. (C) 2021 Published by Elsevier Ltd.