Zn) to dynamic glazings with applications for thermal emissivity (e.g., Ag) or windows (e.g., Cu, Bi, Ag, and Zn). In each of these systems, a layer of metal is electroplated for the system's designed purpose: energy storage for batteries, [1][2][3][4] infrared light modulation for dynamic thermal emissivity, [5] and visible light modulation for dynamic windows. [6][7][8] The mechanical stability of the electrodeposited films is paramount for the devices' durability in practical applications. Mechanical failure can occur in the form of detached dendrites, "dead" metal, pits, and cracked or delaminated films, which usually result in loss of active material leading to device failure. The mechanics of electrodeposited Li has been extensively studied for Li metal batteries. [9,10] Dynamic windows allow for electronic and user control over light and

Dynamic windows based on reversible metal electrodeposition are an attractive way to enhance the energy efficiency of buildings and show great commercial potential. Dynamic windows that rely on liquid electrolytes are at risk of short circuiting when two electrodes contact, especially at larger-scale. Here we developed a poly (vinyl alcohol) (PVA) gel polymer electrolyte (GPE) with 85% transmittance, that is, sufficiently stiff to act as a separator. The GPE is implemented into windows that exhibit comparable electrochemical and optical properties to windows using a liquid electrolyte. Furthermore, the GPE enables the fabrication of windows with dual-working electrodes (WE) and a metal mesh counter electrode in the center without short-circuiting. Our dual-WE PVA GPE window reaches the 0.1% transmittance state in 101 s, more than twice the speed of liquid windows with one working electrode (207 s). Additionally, each side of the dual-WE GPE window can be tinted individually to demonstrate varied optical effects (i.e., more reflective, or more absorptive), providing users and intelligent building systems with greater control over the appearance and performance of the windows in a single device architecture.