SiO2: A Novel Electrolyte for High-Performance All-Solid-State Electrochromic Devices

For the practical application of electrochromic devices (ECDs), the development and preparation of high-performance electrolyte materials is one of the urgent problems to be solved. In this work, an all-solid-state ECD with the integrated structure of glass/ITO/WO3/Li/SiO2/NiO/ITO has been prepared by the magnetron sputtering method. The amorphous SiO2 film prepared by pulsed direct current reactive magnetron sputtering was used as the electrolyte layer in the ECD for the first time and shows promising potential due to its ultrahigh transparency, good intrinsic electronic insulation, and loose structure for fast ion conduction. The ECD exhibits low leakage current density (8.5 μA cm–2 for bleaching and 43.4 μA cm–2 for coloring), high optical modulation (ΔT = 71.9% at 707 nm), fast response speed (1.1 s for the bleaching process and 8.5 s for the coloring process), excellent cycle stability, and high coloration efficiency (126.4 cm2 C–1). This work not only indicates that SiO2 as a dielectric material can be used as the electrolyte layer in all-solid-state ECDs but also provides new avenues in the selection of electrolyte materials for the preparation of high-performance ECDs.