Agar-Based Gel Electrolyte for Electrochromic Device Application

Abstract

Gel Polymer Electrolytes (GPE) based on agar and containing LiClO₄ have been prepared, characterized and applied to electrochromic devices. The ionic conductivity revealed the best result of 6.5 × 10⁻⁵ S/cm for the sample with 17 wt.% of LiClO₄, which increased to 5.4 × 10⁻⁴ S/cm at 72°C. The GPE have been used in electrochromic devices (ECD) with K-glass/WO₃/GPE/CeO₂-TiO₂/K-glass configuration. The ECD changed transmittance values up to 30% between the colored and transparent states. The charge density measurements revealed an increase of 5.5 to 7.5 mC/cm² from the first to 500th cycles and then a decrease to 4.4 mC/cm² during the next 4500 cycles. Coloration efficiency (η) of 25 cm²/C was obtained.

Keywords:

• Agar
• electrochromic devices
• gel polymer electrolyte
• ionic conductivity

Acknowledgments

The authors are indebted to FAPESP, CAPES and CNPq, University of Minho and Fundação para a Ciência e Tecnologia (contracts PEst-C/QUI/UI0686/2011), for the financial support given to this research.