Scalable preparation of hierarchical porous activated carbon/graphene composites for high-performance supercapacitors

Hierarchical porous activated carbon particles covered with graphene were prepared by spray-drying a GO/maltodextrin aqueous suspension followed by carbonization and activation. The as-prepared core-shell particles had a high specific surface area (up to 2457 m(2) g(-1)) and exhibited an outstanding specific capacitance (up to 405 F g(-1) at 0.2 A g(-1), 299 F g(-1) at 1 A g(-1) and 199 F g(-1) at 50 A g(-1)) along with excellent cycling stability, high energy density and power density in a KOH electrolyte. Moreover, the spontaneous formation of the core-shell structure during the spray-drying process was verified by DFT calculations with the support of XPS chemical analysis and TEM characterization. This designable and controllable strategy of spray-drying could be introduced to design and develop new composite materials with a core-shell structure for potential applications in energy storage, catalysis and adsorption.