Graphene architecture interpenetrated with mesoporous carbon nanosheets promotes fast and stable potassium storage

Carbon materials are considered as prospective anode candidates for potassium ion batteries (PIBs). However, the low-rate capability is hampered by slow K+ diffusion kinetics and obstructed electron transport of carbon-based anodes. In this work, calcium D-gluconate derived mesoporous carbon nanosheets (CGC) were interpenetrated into the architecture of reduced graphene oxides (RGO) to form the composites of two-dimensional (2D)/2D graphene/mesoporous carbon nanosheets (RGO@CGC). CGC as a rigid skeleton can prevent the graphene layers from restacking and maintain the structural stability of the 2D/2D carbon composites of RGO@CGC. The mesopores in CGC can shorten the path of ion diffusion and facilitate the penetration of electrolytes. RGO possesses the high surface-to-volume ratio and superior electron transport capability in the honeycomb-like 2D network consisting of sp2-hybridized carbon atoms. Especially, the π-π stacking interaction between CGC and RGO enhances stable composite structure formation, expedites interlayer-electron transfer, and establishes three-dimensional (3D) ion transportation pathways. Owing to these unique structure, RGO@CGC exhibits fast and stable potassium storage capability. Furthermore, the effects of binders and electrolytes on the electrochemical performance of RGO@CGC were investigated. Finally, Prussian blue was synthesized as a positive electrode to explore the possibility of RGO@CGC as a full battery application.