Quasi-Solid-State Electrochromic Energy Storage Devices with Long-Term Stability

Electrochromic energy storage devices (EESDs) offer the unique capability to monitor real-time energy storage levels while simultaneously recovering energy to reduce the power consumption in electrochromic devices (ECDs). PB/Zn EESDs stand out as a system with tremendous potential and promising applications, enabling simultaneous energy conservation and storage. Herein, we present a PB/Zn quasi-solid-state EESD, which incorporates an in situ photopolymerized Zn²⁺–K⁺ hybrid quasi-solid-state electrolyte. This electrolyte demonstrates an impressive ionic conductivity of 5.47 mS cm^–1 at room temperature, primarily owing to its high electrolyte content and the enhanced ion transport facilitated by the three carboxyl groups bridging the ethoxylated trimethylolpropane triacrylate (ETPTA) monomer. Thanks to the high ionic conductivity of the quasi-solid-state electrolyte and the synergistic effects between Zn²⁺ and K⁺ hybrid ions, the PB/Zn quasi-solid-state EESD exhibits outstanding optical modulation (62.91% @ 700 nm), excellent coloration efficiency (213.95 cm² C^–1), a high average discharge voltage of 1.2 V, and exceptional long-term cycle stability, maintaining 67% of its capacity and 90.9% of its optical modulation after 3000 cycles. The use of in situ polymerization effectively resolves the issue of interfacial contact between the electrolyte and the electrochromic layer, contributing to the overall performance of device. This uncomplicated and direct device fabrication method, combined with quasi-solid-sate electrolytes featuring high ionic conductivity, holds promise for a variety of electrochromic devices.