Mesoporous carbon nanospheres inserting into graphene sheets for flexible supercapacitor film electrode

A flexible graphene (GN)-based film has been prepared by flow-directed assembly from a complex dispersion of GN and mesoporous carbon nanosphere (MCS) functionalized with poly dimethyl diallyl ammonium chloride. Morphology analysis displays that the presence of MCS has effectively prevent the restacking of individual GN sheets, favoring electrolyte ions easier access to the surfaces of GNs in forming electric double-layers. In application as a supercapacitor in 1 M KOH electrolyte, GN/MCS film shows superior electrochemical performance, including high specific capacitance (211 F g−1 at 0.2 A g−1), good rate capability (61% capacity retention at 20 A g−1) and excellent electrochemical stability (4% capacity loss after 5000 cycles).