Investigations on capacitive properties of the AC/V2O5 hybrid supercapacitor in various aqueous electrolytes

Amorphous V2O5 sample was prepared by a melt quenching method. The hybrid supercapacitor was fabricated with V2O5 positive electrode and activated carbon (AC) negative electrode in various aqueous electrolytes. Its electrochemical properties were determined by cyclic voltammetry, charge/discharge test and electrochemical impedance spectroscopy. The results showed that species of aqueous electrolyte, current density, potential range and the active mass ratio of AC to V2O5 had great effect on the capacitive properties. In the potential range of (−0.3 to 0.7) V, the hybrid capacitor delivered the specific capacitance of 32.5 F g−1 at a current density of 200 mA g−1 in 2 mol L−1 NaNO3 solution when the mass ratio of AC to V2O5 was 1:1, and simultaneously exhibited excellent capacity retention. The specific capacitance only slightly decreased with the increasing current density. When the mass ratio of AC to V2O5 was increased to 3:1, the capacitance of the AC/V2O5 hybrid capacitor was similar to that of the V2O5/V2O5 symmetric cell.