Vibrant Color Palettes of Electrochromic Manganese Oxide Electrodes for Colorful Zn‐Ion Battery.

Colorful electrochromic batteries operating in the visible region, which display their residual capacity through real‐time color variation, have recently attracted tremendous attention due to the ever‐rising demands of smart electronics. However, the currently available electrochromic batteries incur certain serious limitations, such as, low capacity utilization, non‐aesthetic versatility, and unsatisfactory performance in practical applications. Manganese oxide, as an extensively used cathode material in zinc‐ion batteries (ZIBs), can yield a prominently high energy density, but with a poor electrochromic performance. By designing a metamaterial with a photonic metastructure, manganese oxide can be remolded into an attractive electrochromic electrode, which shows vibrant color palettes capable of accurately displaying the stored energy level. Based on the combined oxidic and reductive coloration in the as‐prepared manganese oxide electrodes, the developed electrochromic ZIB exhibits a high capacity of 283 mAh g−1 at 0.2 A g−1, with an energy retrieval rate up to 72% during the round‐trip solar charging and galvanostatic discharging processes. This electrochromic ZIB with vibrant color palettes exhibits promising application in next‐generation electrochromic devices with multiple functionalities. [ABSTRACT FROM AUTHOR]