Preparation and properties of Ca² -doped vanadium bronze as electrode material of supercapacitor

Vanadium bronze was prepared by traditional acidification process with sodium vanadate as precursor, and its electrochemical capacitance quantitatively measured by cyclic voltammetry and galvanostatic charge-discharge methods in 1 mol/L NaNO₃ solution. The effects of the precursor concentration, doping cation species and amount of doping cation on the performance of vanadium bronze were examined. Electrochemical investigation reveals that the product contains the optimal capacitance of 120 F/g when the concentration of Na₃VO₄ is 0.1 mol/L. The sample doped with 0.25 mol/L Ca² exhibits improved capacitance of 168 F/g in the initial circle and maintains 131 F/g capacitance after 100 circles. Its electrochemical properties are better than V₂O₅ and Na-doped vanadium oxide.