Electrochemical performance of honeycomb graphene prepared from acidic graphene oxide via a chemical expansion method

Abstract

• Simple, low-energy and scalable one-step chemical expansion of graphene. • High-yield (>90%) preparation of of nanocrystalline chemically expanded graphene. • Specific capacity of 283.8F·g −1 at 1 A·g −1 , and excellent rate capability. • Excellent capacity retention of ≈87% after 5000 cycles at 20 A·g −1. High-performance electrode materials are particularly important for the next-generation of supercapacitors with enhanced specific capacity and cycle stability. In this study, a simple and scalable thermal expansion method is used to convert acidic graphite oxide (AGO) into chemically expanded graphene (CEG) nanostructure, with a honeycomb morphology consisting of 2–3 graphene layers. The CEG produced by the thermal expansion of AGO under modified conditions of time and duration (CEG-2) exhibits a substantially large specific surface area of around 388 m 2 ·g −1 , in comparison to value of 6 m 2 ·g −1 recorded on the virgin superconducting graphite powder. This provides the CEG-2 material with an excellent specific capacitance of 283.8F·g −1 , recoded at 1 A·g −1 . The cycle stability of CEG-2 is characterized to be highly desirable with a retention rate of around 87% after 5000 cycles. The results obtained suggest the enhanced electrochemical performance of CEG.