Aqueous alkaline electrolytes for dynamic windows based on reversible metal electrodeposition with improved durability

Abstract

Dynamic windows, which have electronically tunable transmission, are desirable for buildings and automobiles due to their aesthetics and ability to reduce lighting, heating, and cooling energy costs. Reversible metal electrodeposition has recently emerged as a promising alternative to dynamic windows based on electrochromic materials. In this manuscript, we develop alkaline electrolytes that facilitate the reversible electrodeposition of Bi and Cu. Through spectroelectrochemical measurements, we determined that a chelating ligand can be used to design optically reversible devices that exhibit sufficient Bi³⁺ solubility in alkaline media. Unlike previously studied acidic Bi–Cu electrolytes, these alkaline electrolytes do not degrade the tin-doped indium oxide transparent conductors typically used in dynamic windows. As a result, we demonstrate that practical two-electrode 25 cm² dynamic windows with these alkaline electrolytes exhibit superior durability to those containing acidic electrolytes. These results are important for the advancement of robust reversible metal electrodeposition technologies.