Effects of various factors on capacitive properties of VOx·nH2O powders in aqueous electrolyte

In this work, effects of drying temperature, pH of aqueous electrolyte and current density on capacitive performance of VOx·nH2O material were firstly investigated. VOx·nH2O powders were prepared by a melt quenching method. The samples were characterized by X-ray diffraction analysis (XRD) and Fourier transform infrared (FTIR). The capacitive properties of VOx·nH2O samples were examined by cyclic voltammetry and galvanostatic charge/discharge test. VOx·nH2O sample which was obtained at the drying temperature of 80 °C, delivers a maximum specific capacitance of 227.3 F g−1 and exhibits excellent capacity retention in the potential range of −0.3 to 0.7 V at a current density of 200 mA g−1 in NaNO3 solution with pH 2.