Electrochemical Rejuvenation of Anodically Coloring Electrochromic Nickel Oxide Thin Films

Abstract

Nickel oxide thin films are of major importance as anodically coloring components in electrochromic smart windows with applications in energy-efficient buildings. However, the optical performance of these films degrades upon extended electrochemical cycling, which has hampered their implementation. Here, we use a potentiostatic treatment to rejuvenate degraded nickel oxide thin films immersed in electrolytes of LiClO₄ in propylene carbonate. Time-of-flight elastic recoil detection analysis provided unambiguous evidence that both Li⁺ ions and chlorine-based ions participate in the rejuvenation process. Our work provides new perspectives for developing ion-exchange-based devices embodying nickel oxide.