Reversible electrochemical mirror devices

• Main Author: Eh, Alice Lee Sie
• Other Authors: Lee Pooi See
• Format: Thesis-Doctor of Philosophy
• Language: English
• Published: Nanyang Technological University 2021
• Subjects: Engineering::Materials
• Online Access: https://hdl.handle.net/10356/146626; https://doi.org/10.1039/C7TC01070B; https://doi.org/10.1002/advs.201903198
• Institution: Nanyang Technological University

Reversible electrochemical mirror (REM) electrochromic devices with merits of various optical states, facile device assembly, and cost effectiveness are attractive alternatives to conventional electrochromic devices. Current REM works are dominated by Ag metal, which is highly costly, poor cycling stability in the reflectance mode, and slower switching speed. This thesis hypothesized that by judiciously selecting the electrolyte components and understanding the electrochemistry of Cu deposition and dissolution, Cu REM can be realized. As an electrochemically active material, Cu can be electrochemically tuned to achieve different redox states with controlled electrical bias. By controlling the different redox states of Cu, various optical states can be attained in the REMs. The current bottleneck in REM is the poor durability in the reflectance mode. The pure Cu REM functions based on Cu metal electrodeposition and dissolution, of which the reversibility may not be satisfactory without the assistance of an alloying element. With the incorporation of an alloying element, it could assist in the electrochemical deposition and dissolution of Cu and hence, promote reversibility. From the kinetics study, the electrochemical deposition of CuSn film is relatively fast. Sn serves to provide a nucleation layer during electrodeposition as validated using Johnson–Mehl–Avrami–Kolmogorov (JMAK) analysis. Furthermore, a hybridization approach, with its well-tailored electrolyte combination and optimization, has been designed for development of high-performance and safe REM electrolyte. The established electrolyte delivers superior electrochemical behavior, stability, current efficiency, and ionic conductivity of the hybrid electrolyte compared to aqueous and non-aqueous electrolytes.