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

Abstract

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 m² 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.