Construction of NiCo-OH/Ni3S2 core-shell heterostructure wrapped in rGO nanosheets as efficient supercapacitor electrode enabling high stability up to 20,000 cycles

Abstract

Inspite of the high theoretical capacitance of transition metal hydroxides, they continue to suffer low conductivity and weak structural robustness leading to unsatisfactory electrochemical performance. Systematic design of core?shell heterostructure composed of different elements with peculiar electronic properties is effective to amplify the overall electrochemical performance. Herein, this study proposes a novel porous reduced graphene oxide modified nickel cobalt hydroxide/nickel sulphide (rGO@NiCo-OH/Ni3S2) nanocomposite prepared through a facile three-step hydrothermal method for supercapacitor application. The three-dimensional (3D) network benefits from the high surface area of 189 m2 g?1, the core stability and the interwoven nanowires, which act as conductive channels, presenting exceptionally good electrochemical properties. The rGO@NiCoOH/Ni3S2 electrode does not only delivers impressive specific capacitance of 2694F g?1 at current density of 2 A g?1. Moreover, when integrated into an asymmetric supercapacitor (ASC), the rGO@NiCo-OH/Ni3S2-based device displays high energy density of 53.5 Wh kg?1 at power density of 760 W kg?1, exhibits excellent cycling stability (95.5% capacitance retention after 20,000 cycles) and lights 2 V light emitting diode (LED) sustained for 11 min.