Electrochromic (EC) windows based on reversible metal electro-deposition/dissolution (RME) are exciting alternatives to static lighting control using blinds and shades. However, the difficulty of reversibly and uniformly electrodepositing large-area metal layers seriously hinders the development of RME-type EC windows. In this paper, we develop a novel EC system based on reversible oxide electro-deposition/dissolution (ROE) of MnO2, achieving a profound and bistable color change between rust brown and completely transparent. This ROE-MnO2 system exhibits a significantly high optical modulation amplitude (ΔT) without any deterioration within 1000 switching cycles (ΔT 550nm actually increases from 44.8 % up to 46.9 % after the cycling test), which is almost double compared to the traditional cation-insertion/extraction triggered MnO2 (RCI-MnO2) EC system. This work may inspire the exploration of novel ROE-type EC systems.
