Facile fabrication and improved supercapacitive performance of exfoliated graphene with hierarchical porous structure

Abstract As a promising electrochemical storage material, graphene has drawn tremendous attention due to its fascinating features, such as excellent mechanical flexibility, high specific surface area and superior conductivity. Nevertheless, the severe restacking of graphene sheets decreases the active surface area and decelerates the ion transport kinetics, hindering the practical application. Literatures reveals that constructing an exfoliated holey sheet structure helps solve this problem. In this work, the novel porous reduced graphene oxide with exfoliated sheets is fabricated via a hydrothermal assembly-calcination method by using Ni(NO3)2•6H2O as the activator. The dosage of Ni(NO3)2•6H2O is optimized according to the electrochemical properties of the corresponding electrode materials for the three-electrode supercapacitors. The results show that the optimal p-RGO-5 displays a high specific capacitance of 253.8 F g−1 at 1.0 A g−1. Moreover, the p-RGO-5-based symmetric supercapacitor delivers a specific energy of 24.67 W h kg−1 at the specific power of 400.00 W kg−1, in addition to superior cycling stability and high rate capability. Our work offers an effective approach for fabricating porous graphene, which is promising in the fields of energy conversion and storage devices.