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

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 9.5 nm, 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 947.4 F g(-1) at the current density of 0.5 A g(-1), and great rate capability, remaining 725.4 F g(-1) at the high current density of 10.0 A g(-1). The specific capacitance of the composites decays by only 2.1% after 3000 cycles at the current density of 10.0 A g(-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. (C) 2014 Elsevier B.V. All rights reserved.