In Situ Room-Temperature Spontaneous Gelation Coupled with Asymmetric Viologen for High-Performance Electrochromic Devices.

Abstract

The inherent trade-off between performance and safety in traditional liquid and all-solid-state electrolytes poses significant challenges to the commercialization of electrochromic devices. To address these issues, this study developed a high-performance semi-interpenetrating polymer network ionic gel electrolyte made of poly(1,3-dioxolane) and poly(methyl methacrylate). Using a lithium bis(trifluoromethanesulfonyl)imide-trifluoroacetic acid co-initiation system, the precursor undergoes efficient in situ ring-opening polymerization and spontaneous curing at room temperature, without requiring external stimuli (e.g., heating or light irradiation) or solvent evaporation. This approach ensures complete wetting of the electrode surface, streamlining the fabrication process and facilitating scalable device fabrication. The gel electrolyte achieves an impressive ionic conductivity of up to 3.32 mS cm^-1. When paired with a specially designed asymmetric viologen compound, the electrochromic device exhibits superior overall performance, characterized by high optical contrast and exceptional cycling stability, even outperforming conventional organic liquid-electrolyte systems. This work presents a synergistic strategy that integrates spontaneous in situ gelation with molecular engineering, offering a promising pathway toward next-generation electrochromic devices.