Repairable electrochromic energy storage devices: A durable material with balanced performance based on titanium dioxide/tungsten trioxide nanorod array composite structure

Abstract

Electrochromic-capacitive bifunctional materials have been widely developed in recent years due to their broad application prospects. However, the failure to achieve all-round excellent performance simultaneously, as well as the limited stability restricted their large-scale commercialization. Here, we prepared a TiO2/WO3 nanorod composite material, which showed balanced electrochromic and capacitive properties without any significant shortcoming in all aspects. Generally, the material possessed excellent coloration efficiency (153.1 cm2 C−1), fast color switching response (10/10s) and high capacitance (557.7 F g−1 at 1 A g−1). In addition, a new concept of “stability in industrial sense” was firstly proposed to redefining the durability of materials. The decline of material stability during cycles was fully explained by a theoretical model of “ion trap”, which contained two categories: (1) eliminable trap and (2) non-eliminable trap. The eliminable trap could be removed by a de-trapping treatment, so that all the properties of declined materials could be restored, while the non-eliminable trap couldn’t be removed.