A high-performance electrochromic device assembled with hexagonal WO3 and NiO/PB composite nanosheet electrodes towards energy storage smart window

Functions of electrochromism and energy exchange can be achieved by redox reactions , which indicate designing a bi-functional electrochromic energy storage device (EESD) is feasible. In this paper, a NiO/PB composite nanosheet electrode was prepared via loading Prussian blue (iron (Ⅲ) hexacyanoferrate (Ⅱ), PB) nanoparticles on the surface of NiO nanosheets, meanwhile, a high-performance WO 3 negative electrode was also prepared via novel erythritol-assisted hydrothermal method with NH 4 Cl used as capping agent. The designed EESD exhibited properties of large optical modulation (67.6% at 630 nm), high coloration efficiency (109.6 cm 2  C -1 ), fast switching speed (2.8/7.9 s for bleaching/coloration) and long cycle life (ΔT remaining was 84.1% after 4000 cycles). Meanwhile, the EESD also obtained attractive energy storage properties at a potential window from 0 to +1.3 V. Impressively, the EESD exhibited a high areal capacitance of 11.50 mF cm -2 at current density of 0.05 mA cm -2 and the process of charging/discharging can be repeated at least 4000 cycles with a little decay. Therefore, the bi-functional EESD exhibits high promising application prospect.