Polyoxotungstate/W18O49 nanocomposite with a bird-nest-like network supports high-performance electrochromic supercapacitors

The W 18 O 49 /[PEI/P 2 W 18 ] 20 film with a unique bird-nest-like network structure exhibits excellent electrochromic energy storage capacity. The ECSC based on this film has a high area capacitance and retention rate, and the storage state is visualized.