Fabry-Perot Cavity-Type Electrochromic Supercapacitors with Exceptionally Versatile Color Tunability

Electrochromic supercapacitors that can change their appearances according to their charged states are presently attracting significant interest from both academia and industry. Tungsten oxide is often used in electrochromic supercapacitors because it can serve as an active material for both benchmarking electrochromic devices and high-performance supercapacitor electrodes. Despite this, acceptable visual aesthetics in electrochromic supercapacitors have almost never been achieved using tungsten oxide, because, in its pure form, this compound only displays a 1-fold color modulation from transparent to blue. Herein, we defy this trend by reporting the first ever Fabry-Perot (F-P) cavity-type electrochromic supercapacitors based only on a tungsten oxide material. The devices were sensitively changeable according to their charge/discharge states and displayed a wide variety of fantastic patterns consisting of different, vivid colors, with both simple and complex designs being achieved. Our findings suggested a novel direction for the aesthetic design of intelligent, multifunctional electrochemical energy storage devices.