Facile synthesis of a reduced graphene oxide wrapped porous NiCo2O4 composite with superior performance as an electrode material for supercapacitors

Abstract

Even though NiCo₂O₄ is considered to be one of the most promising materials for supercapacitor applications, its unsatisfactory rate performance and cycling stability, due to inherently low electrical conductivity, have limited its further growth as a supercapacitor electrode. The present study tries to profitably exploit reduced graphene oxide (rGO) nanosheets as a conducting unit to enhance the electronic conductivity, by a simple hydrothermal technique assisted by ammonia hydroxide, to improve the overall electrochemical performance of NiCo₂O₄ in supercapacitors. The as-prepared NiCo₂O₄–rGO nanocomposite consists of NiCo₂O₄ hexagons wrapped in conducting rGO sheets, which ensure a short ion diffusion distance, percolating electron conducting pathways, and stable structural integrity. Such a feasible design provides good synergism between the rGO and the NiCo₂O₄, resulting in better electrochemical performance. As a result, this nanocomposite displays impressive overall electrochemical performance, in aspects such as promising capacitance (1185 F g⁻¹ at a current density of 2 A g⁻¹) and remarkable cycling stability (98% capacitance retention after 10 000 charge–discharge cycles at 2 A g⁻¹). This facile method could be beneficial for preparing similar materials that require high electronic conductivity.