A multi-chromic supercapacitor of high coloration efficiency integrating a MOF-derived V2O5 electrode

Abstract

Modern technological trends in smart electronic devices demand more intelligent automation. Simultaneous integration of energy storage and multicolor electrochromism in a single device improves user–device interfacing based on a salient human-readable output. In this work, primarily metal–organic framework (MOF) derived V₂O₅ was synthesized which, as an electrochromic material, shows high optical modulation of 35% at 485 nm, with very fast switching speeds (2.9/3.4 s for coloring/bleaching). The multiple coloration states of the V₂O₅ electrode make it worthy for further integration as a smart negative electrode in a multicolored electrochromic asymmetric supercapacitor, where the electrochromic polyaniline electrode serves as the counter electrode. The device demonstrates a high coloration efficiency of 137.2 cm² C⁻¹ and an areal capacitance of 12.27 mF cm⁻² and an energy density of 2.21 × 10⁻³ mW h cm⁻² at a current density of 0.05 mA cm⁻². By virtue of its different chromatic states during charging and discharging, smart visual tracking of the state of charge of the supercapacitor can be realized. Such a design of energy storage devices will have promising practical application in futuristic smart multifunctional electronic devices.