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

摘要

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.