Nanorod-assembled NiCo2O4 hollow microspheres assisted by an ionic liquid as advanced electrode materials for supercapacitors

Abstract

In this work, nanorod-assembled NiCo2O4 hollow microspheres have been successfully prepared by an ionic liquid-assisted hydrothermal method for the first time. The as-obtained nanorod-assembled NiCo2O4 hollow microspheres manifest a high specific capacitance (764 F g−1 at 2 A g−1), exceptional rate capability (53.5% of capacity retention at 30 A g−1) and good cycling stability (101.7% of initial capacity retention after 1500 cycles). The superior electrochemical performance can be attributed to the unique hollow micro-/nanostructure, which can provide more active sites for the faradic redox reaction, provide an easy electrolyte penetration path and alleviate the volume change during the charge-discharge process. These results suggest that the nanorod-assembled NiCo2O4 hollow microspheres could be promising electrode materials for supercapacitor applications. Additionally, this synthetic method can be extended to the fabrication of other hollow micro-/nanostructure materials for energy and other related applications.