KMnO4-assisted synthesis of oxygen-containing porous graphene with high gravimetric and volumetric performances for supercapacitor

Graphene becomes a promising electrode material for supercapacitor because of their high theoretical specific surface area and good conductivity. Nevertheless, the main disadvantage of graphene is the irreversible agglomeration because of the strong interlayer van der Waals force, which is significantly decreases the surface area, thus resulting in poor electrochemical performance. Herein, we report a new and facile strategy to synthesize rich oxygen-containing porous graphene (OPG) using KMnO4 as activator precursor. The optimized OPG-600 samples possess crumpled porous framework with a suitable surface area and massive oxygen-containing functional groups. Benefiting from their synergistic influence, the OPG-600 electrode displays a high gravimetric and volumetric capacitance of 363.3 F g-1 and 342.5 F cm-3 at 0.5 A g-1 and good rate performance (240 F g-1 and 226.3 F cm-3 at 30 A g-1). More interestingly, the OPG-600 symmetric supercapacitor displays a high volumetric energy density of 19.2 Wh L-1 and superior electrochemical stability.