Dual-functional electrochromic and energy-storage electrodes based on tungsten trioxide nanostructures

In this paper, high-performance dual-functional electrodes based on tungsten trioxide (WO 3 ) nanostructures are developed, which successfully realize the combination of electrochromism and energy storage. The WO 3 nanostructures with various morphologies (nanospindles, nanopetals, nanosheets, and nanobricks) were prepared via a facile hydrothermal process. It has been found that the WO 3 nanosheets possess large surface area and porous architecture, significantly increasing the amount of active sites and facilitating the transport of Li + ions. As dual-functional electrode, WO 3 nanosheets present enhanced electrochemical properties including wide optical modulation (64.5%), fast switching time (6.6/3.8 s), great coloration efficiency (48.9 cm 2  C −1 ), and high areal capacitance (14.9 mF cm −2 ). Furthermore, the WO 3 nanosheets could bridge electrochromic behaviors with energy storage by changing color during the charge/discharge processes. The results demonstrate great potential of WO 3 nanosheets for electrochromism and energy storage applications. ᅟ