Scalable exfoliation and activation of graphite into porous graphene using microwaves for high–performance supercapacitors

Activated few–layered graphene (a–FLG) materials with porous structures are prepared using a KOH–assisted microwave irradiation technique from natural graphite. The employment of KOH as a chemical etchant efficiently activates the surface pore structure of graphene during the exfoliation of graphite exposed to microwave irradiation. The resultant a–FLG materials exhibit favorable and tailorable large surface areas and porous structures for the deposition of electrochemically active MnO2. When measuring electrochemical characteristics, MnO2/a–FLG exhibits a high specific capacitance (265 F/g), high rate capability, and excellent long–term stability. Moreover, asymmetric supercapacitor devices fabricated using a–FLG as a negative electrode and MnO2/a–FLG as a positive electrode show high energy (40.8 Wh/kg) and power (16.3 kW/kg) densities with high capacitance retention (96% over 10000 cycles). [Display omitted] •Preparation of porous graphene sheets using KOH–assisted microwave irradiation.•Characterization of a–FLG materials with high surface area and porous structure.•Demonstration of energy storage performances of a–FLG electrodes.•High energy and power densities of asymmetric supercapacitor devices.