Electrolyte for Improved Durability of Dynamic Windows Based on Reversible Metal Electrodeposition

Electrochromic, “smart” windows allow users to control light and heat flow into and out of buildings or vehicles without sacrificing their view. Despite the appeal of dynamic windows, they have yet to achieve extensive commercialization due to their inability to simultaneously achieve fast, color-neutral tinting over a wide optical dynamic range at a low cost. Reversible metal electrodeposition (RME) is a promising alternative that addresses the drawbacks of existing technologies. Here, we study several possible RME electrolytes at various pHs with different supporting anions. We identify that acidic perchlorate electrolytes permit fully reversible metal electrodeposition without harming the substrate or introducing irreversible side reactions, which was not seen among all other electrolytic compositions. This perchlorate electrolyte shows promising long-term durability, demonstrating 10,000 stable cycles with no evidence of electrode etching. In addition, we construct 15 × 15 cm2 dynamic windows that tint uniformly with fast, color-neutral switching (>60% contrast in <3 min).