Colossal change in capacitance of vo2 near the metal-insulator transition

Abstract

The electrochemical capacitor properties of vanadium dioxide (VO 2) were studied at various temperatures near the metal-insulator transition (25-70°C). Cyclic voltammetry in 1.0M Li2SO4 revealed an anomalous increase in capacitance with increasing temperature. The specific capacitance of conductive rutile VO2 at 70°C was five times higher than that of the poorly conductive monoclinic VO2 at 25°C. Electrochemical impedance spectroscopy showed a decrease in resistance with increasing temperature, consistent with the metal-insulator transition. The results are compared and discussed with other typical electrochemical capacitor materials. © The Electrochemical Society of Japan, All rights reserved.