Graphene wrapped nitrogen-doped active carbon fibers (ACF@GR) of a core-shell structure were successfully prepared by a simple dip-coating method using natural silk as template. Compared to pure silk active carbon, the as-prepared ACF@GR composites exhibit high specific surface area in a range of 1628-2035 m(2) g(-1), as well as superior energy storage capability, an extremely high single-electrode capacitance of 552.8 F g(-1) was achieved at a current density of 0.1 A g(-1) in 6 M KOH aqueous electrolyte. The assembled aqueous symmetric supercapacitors are capable of deliver both high energy density and high power density, for instance, 17.1 Wh kg(-1) at a power density of 50.0 W kg(-1), and 12.2 Wh kg(-1) at 4.7 kW kg(-1) with a retention rate of 713% for ACF@GR1-based supercapacitor. (C) 2016 Elsevier B.V. All rights reserved.