Super high ionic conductivity and an all-weather adaptable LiCl-based hydrogel electrolyte for electrochromic devices

Abstract

Electrochromic devices are expected to operate reliably over a wide range of temperatures, requiring the electrolyte layer to maintain stability under varying environmental conditions. Herein, by introducing the neutral LiCl, we develop a temperature-adaptive hydrogel electrolyte with high ionic conductivity of 6 mS cm⁻¹ at −25 °C, 18 mS cm⁻¹ at RT and 24 mS cm⁻¹ at 80 °C and a transmittance of ∼96%. The electrochromic devices constructed by pairing the hydrogel with an inert Cu electrode and WO₃ thin films show a wide-temperature electrochromic response with amazing optical modulation (72.7% at −25 °C, 86% at RT, and 77% at 60 °C), fast coloring response times as low as 10.8 s at −25 °C, and superior cycling stability with 93.5% retention of their initial transmission modulation after 1000 cycles. This study provides a feasible strategy for developing cost-effective and safe electrochromic devices with super application potential.