Water-in-Salt Electrolytes for Reversible Zinc Electrodeposition for Dynamic Windows

Abstract

Reversible metal electrodeposition (RME) is an emerging and promising method for designing dynamic windows with electrically-controllable transmission, excellent color neutrality, and wide dynamic range. Despite its very negative deposition voltage, Zn is a viable option for metal-based dynamic windows due to its fast switching kinetics and reversibility. Here, we describe the construction of Zn RME dynamic windows using water-in-salt electrolytes (WISe). By systematically comparing different electrolytes, we study the effects of different WISe components on Zn RME spectroelectrochemistry. This insight allows us to design practical two-electrode 25 cm2 Zn dynamic windows, the first examples of RME devices with WISe. We also establish a link between the morphology of the Zn electrodeposits and the optical contrast of the transparent electrodes during switching. Taken together, these studies highlight a potential design strategy for the construction of RME dynamic windows.