▎ 摘　　要

Herein, we demonstrate a unique supercapacitor composite electrode material that is originated from a sustainable cellulosic precursor via simultaneous one-step carbonization/reduction of cellulose/graphene oxide mats at 800 degrees C. The resulting freestanding material consists of mechanically stable carbon nanofibrous (CNF, fiber diameter 50-500 nm) scaffolds tightly intertwined with highly conductive reduced graphene oxide (rGO) sheets with a thickness of 1-3 nm. The material is mesoporous and has electrical conductivity of 49 S cm(-1), attributed to the well-interconnected graphene layers. The electrochemical evaluation of the CNF/graphene composite electrodes in a supercapacitor device shows very promising volumetric values of capacitance, energy and power density (up to 46 F cm(-3), 1.46 W h L-1 and 1.09 kW L-1, respectively). Moreover, the composite electrodes retain an impressive 97% of the initial capacitance over 4000 cycles. With these superior properties, the produced composite electrodes should be the "looked-for" components in compact supercapacitors used for increasingly popular portable electronics and hybrid vehicles.