Electrochemically co-deposited WO3-V2O5 composites for electrochromic energy storage applications

Abstract

In this study, a W-V mixed metal oxide composite thin-film structure comprising tungsten oxide (WO3) and vanadium oxide (V2O5) is prepared using a one-step electrochemical co-deposition method. The electrochromic and electrochemical energy storage applications of the prepared thin films comprising different compositions of WO3 and V2O5 are systematically investigated. The films of the W-V mixed composite, comprising WO3 and V2O5 in the ratio of 1:1, exhibits remarkable electrochromic properties, such as an optimum optical contrast of 60%, a fast coloration response of 4.9 s, and the highest coloration efficiency of 61.5 cm2/C. Furthermore, for the electrochemical energy storage application, a maximum areal capacitance of 38.75 mF/cm2 at an applied current of 0.5 mA/cm2 is obtained. Furthermore, it displays a capacitive retention of 78.5%, even after 5000 charge/discharge cycles. The ameliorated characteristics of both electrochromic and electrochemical energy storage applications are attributed to the (a) unique morphology containing more active sites introduced by both WO3 and V2O5, (b) fast charge transfer kinetics, and (c) redox behavior of both metal ions present in the synthesized W-V mixed metal composite.