V2O5·0.6H2O nanoribbons as cathode material for asymmetric supercapacitor in K2SO4 solution

V2O5·0.6H2O nanoribbons were prepared and their electrochemical behaviors in K2SO4 aqueous solution were investigated. Results show for the first time that K+ ions could intercalate/deintercalate reversibly in the V2O5·0.6H2O lattice. An asymmetric supercapacitor activated carbon/0.5 mol/l K2SO4/V2O5·0.6H2O was successfully assembled, which could be cycled reversibly in the voltage region of 0–1.8 V. This supercapacitor presents an energy density of 29.0 Wh/kg based on the total mass of the active electrode materials, a very good rate behavior with energy density of 20.3 Wh/kg at power density of 2 kW/kg, and also a rather good cycling performance.