Eutectic electrolyte enables reversible Zn electrodeposition-based electrochromic devices with large optical...

Area of Science:

• Materials Science
• Electrochemistry

Background:

• Reversible metal electrodeposition (RME) electrochromic devices (ECDs) are promising for energy-saving applications like smart windows and displays.
• The electrolyte is critical for ion transport, deposition/dissolution reversibility, optical modulation, and device lifespan in RME-ECDs.

Purpose of the Study:

• To develop a high-performance deep eutectic solvent (DES) electrolyte for RME-based ECDs.
• To tailor the solvation structure of the DES electrolyte to optimize its properties.

Main Methods:

• Development of a DES electrolyte with tailored solvation structure.
• Characterization of electrolyte properties including ionic conductivity, voltage window, and operating temperature range.
• Assembly and testing of RME-based ECDs using the developed DES electrolyte.

Main Results:

• The DES electrolyte exhibited high ionic conductivity (6.8-8.0 mS cm⁻¹ at 25 °C) and a stable voltage window (∼2.7 V).
• The electrolyte demonstrated stable performance across a wide temperature range (-20 to 80 °C) and enabled reversible Zn deposition/dissolution.
• The assembled device showed three optical states, high optical modulation (87% from 400-800 nm), and robust cycling stability (87.3% retention after 2400 cycles).

Conclusions:

• The developed DES electrolyte offers a new pathway for creating environmentally friendly, high-performance electrolytes for RME-based devices.
• This work lays the groundwork for advanced RME-ECDs with improved optical modulation and extended service life.