▎ 摘　　要

Graphene-wrapped polyaniline nanofibers were prepared by assembly of negatively charged graphene oxide with positively charged aqueous dispersible polyaniline nanofibers in an aqueous dispersion, followed by the reduction of the graphene oxide. The hybrid material with a graphene oxide loading of 9.1 wt.% displayed a high specific capacitance of over 250 F g(-1) in a 1 M Et4N+center dot BF4-/propylene carbonate electrolyte, a 39.7% increase compared with pristine polyaniline nanofibers. A significant improvement in long-term cycle life was also realized. The hybrid exhibited an initial specific capacitance of 236 F g(-1), which remained as high as 173.3 F g(-1) over 1000 cycles, or a 26.3% decrease, much better than that for pure polyaniline nanofibers. An asymmetric supercapacitor based on this hybrid material and activated carbon was assembled. An energy density of 19.5W h kg(-1) at a power density of 738.95 W kg(-1) was obtained for the cell under an operating voltage window of 2 V. (C) 2012 Elsevier Ltd. All rights reserved.