Nitrogen-functionalized carbon nanofibers (N-CNFs) were prepared by carbonizing polypyrrole (PPy)-coated cellulose NFS, which were obtained by electrospinning) deacetylation of electrospun cellulose acetate NFs, and PPy polymerization. Supercapacitor electrodes prepared from N-CNFs and a mixture of N-CNFs and Ni(OH)(2) showed specific capacitances of similar to 236 and similar to 1045 F g(-1) respectively, An asymmetric supercapacitor was further fabricated using N-CNFs/Ni(OH)(2) and N-CNFs as positive and negative electrodes. The supercapacitor device had a working voltage of 1.6 V in aqueous KOH solution (6.0 M) with an energy density as high as similar to 51 (W h) kg(-1) and a maximum power density of similar to 117 kW kg(-1). The device had excellent cycle lifetime, which retained similar to 84% specific capacitance after 5000 cycles of cyclic voltammetry scans. N-CNFs derived from electrospun cellulose may be useful as an electrode material for development of high-performance supercapacitors and other energy storage devices: