High performance supercapacitor electrode materials based on porous NiCo2O4 hexagonal nanoplates/reduced graphene oxide composites

Abstract

A novel composite with porous NiCo2O4 hexagonal nanoplates deposited on reduced graphene oxide (RGO) sheets is synthesized through a simple hydrothermal method followed by a thermal annealing process. The average side length and thickness of the NiCo2O4 nanoplates are ca. 61 and 9.5nm, respectively. The capacitive performances of the as-prepared composites as electrode materials are investigated. It is found that the NiCo2O4/RGO (NCG) composites exhibit an enhanced capacitive performance as compared with pure NiCo2O4 hexagonal nanoplates and RGO. The NCG composites can achieve a maximum average specific capacitance of 947.4Fg−1 at the current density of 0.5Ag−1, and great rate capability, remaining 725.4Fg−1 at the high current density of 10.0Ag−1. The specific capacitance of the composites decays by only 2.1% after 3000 cycles at the current density of 10.0Ag−1, indicating an excellent cycling stability. The enhanced capacitive performance for NCG composites can be attributed to the structural advantages of high specific surface area, superior electrical properties and well-connected network of the RGO support. The superior capacitive performance demonstrates the promising application of the NCG composites in electrode materials for supercapacitor.