Bi-functional flexible electrodes based on tungsten trioxide/zinc oxide nanocomposites for electrochromic and energy storage applications

In this paper, the tungsten trioxide/zinc oxide (WO3/ZnO) nanocomposites were formed on flexible substrates by combining facile hydrothermal process and pulsed laser deposition (PLD) method. As bi-functional electrodes, the WO3/ZnO nanocomposites possess large specific surface area and a great number of micro channels, significantly increasing the area of WO3 active layer and facilitating the diffusion of Li+ ions during the electrochemical process. Compared with dense WO3 film, WO3/ZnO nanocomposites exhibit enhanced electrochromic and capacitive performance of wider optical contrast (68.2%), greater coloration efficiency (80.6 cm2C−1) and higher areal capacitance (15.24 mF cm−2). Furthermore, based on the WO3/ZnO nanocomposites structure, a novel flexible electrochromic-supercapacitor was demonstrated, which functions as a smart energy storage device able to visually monitor the level of stored energy by rapid and reversible color variation. The results present great potential of WO3/ZnO nanocomposites for electrochromic and energy storage applications.

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