Interfacial Charge Transfer and Zinc Ion Intercalation and Deintercalation Dynamics in Flexible Multicolor Electrochromic Energy Storage Devices

Bifunctional electrochromic devices integrating electro-chromism and energy storage have attracted extensive attention in recent years. Here, zinc-ion-intercalation-based multicolor electrochromic energy storage devices (EESDs) based on a free-standing Zn2+-based polymeric electrolyte membrane (ZPEM) and a nanocrystal-in-glass V2O5 thin film were constructed. Evolution of the interlayer spacing, V-O-related bonds, and chemical compositions of the V2O5 thin films with zinc ion intercalation and deintercalation is elaborated in a liquid Zn(CF3SO3)(2)-propylene carbonate (PC) electrolyte. Impressively, highly reversible multi-electrochromism among greenish-blue, yellowish-green, greenish-yellow, faint-yellow, yellowish-orange, and reddish-orange colors is observed in both flexible V2O5 thin films and flexible ZPEM/V2O5/indium tin oxide (ITO) EESDs, which enjoy the benefits from the free channel originating from the large interlayer spacing, the buffering effect of the amorphous phase in the host nanocrystal-in-glass V2O5 matrix, the robust electrostatic interactions between the host V2O5 and guest Zn2+, and Faradaic redox reactions at the Zn2+/V2O5 active interface. The flexible multicolor EESD based on zinc ion intercalation and deintercalation exhibits remarkable electrochromic and energy storage performance with a high transmittance modulation of 57.88%, an excellent coloration efficiency of 36.91 cm(2) C-1, a superior specific capacitance of 51 mu F cm(-2), an enhanced rate capacity, and a pseudocapacitive feature, making it a promising candidate for cost-efficient, environmentally friendly, and bifunctional electrochromic devices.