Anti-freezing polyacrylamide hydrogel electrolyte for rapid response self-powered electrochromic devices

Abstract

Self-powered electrochromic devices (SECDs) that employ metal electrodes have attracted considerable attention owing to their low voltage, low energy consumption, and ability to function independently from external power supplies; however, further research is still needed to enhance aspects such as portability, freeze resistance, rapid responsiveness, etc. Herein, low temperature resistance and high ionic conductivity of the gel electrolyte were achieved through the mixed solvent immersion method. The highest ionic conductivity of 24.5 mS cm⁻¹ was achieved at 2 M concentration of aluminum perchlorate (Al(ClO₄)₃) at room temperature, and an ionic conductivity of 10.1 mS cm⁻¹ was achieved at −40 °C. The device assembled with this electrolyte exhibits a coloring response time as low as 2.39 seconds at room temperature and 9.62 seconds at −40 °C, with a modulation of 77.0%. Additionally, due to the inherent oxidizing properties of Al(ClO₄)₃, the SECDs using gel electrolytes of different components exhibited an adjustable self-bleaching response time from 29.92 min to 2.93 min after circuit disconnection. Based on the excellent stability and reliability of the gel electrolyte, the SECDs can be precisely customized to function without packaging, thereby significantly advancing their applicability in low temperature environments and enabling tailored application scenarios.