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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. In this manuscript, 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.
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Transparent, High‐Charge Capacity Metal Mesh Electrode for Reversible Metal Electrodeposition Dynamic Windows with Dark‐State Transmission <0.1%
Abstract Dynamic windows allow user control over light and heat flow to save energy and maximize comfort. Reversible metal electrodeposition (RME) dynamic windows can uniquely tint to a color‐neutral privacy state (0.1% visible light transmission). The design parameters of transparent metal mesh counter electrodes for high‐contrast RME dynamic windows: high transparency, charge capacity and surface area with low haze, sheet resistance and cost are discussed, concluding that woven metal meshes meet these design parameters. Electroplated current is measured on an indium tin oxide electrode and two meshes with different wire spacings, showing the meshes’ cylindrical geometry enable them to draw more current per square area. The mesh material composition is analyzed to ensure cycling durability in a CuBi electrolyte by developing a transparent mesh with an inert core (stainless steel, SS), a thin Au coating, and a high charge‐capacity (1.5 C cm−2) CuBi outer coating. The study demonstrates that the films maintain a consistent Cu:Bi ratio and optical properties after 250 privacy cycles or 1500 cycles to 10% transmission, showing that the Cu and Bi coating is effective in keeping the films from becoming Cu rich with cycling. Finally, a 100 cm2device with excellent uniformity and color neutrality is demonstrated.
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- Award ID(s):
- 2127308
- PAR ID:
- 10370150
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Advanced Energy Materials
- Volume:
- 12
- Issue:
- 32
- ISSN:
- 1614-6832
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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