Thin film of CeO2-SiO2:: a new ion storage layer for smart windows

Thin solid films of CeO2-SiO2, used as a counter-electrode layer in electrochromic devices, were prepared by the sol-gel dip coating, using an aqueous-based process. The influence of the SiO2 addition on electrochemistry of the CeO2 oxide coatings was determined by chronoamperometric measurements. The films exhibit a larger charge storage capacity, which was determined as a function of the coatings thickness. The peak occurrence in the chronoamperometric curve during the deintercalation of lithium ions in the cerium/silicon films is analyzed in terms of trapping energy levels for Li+ ions into the film. In situ UV-Vis spectroelectrochemical measurements of the CeO2-SiO2 coatings indicated that the films remained transparent in the visible spectral range during the intercalation process. Powders were characterized by X-ray diffraction after the same thermal treatment of the films, indicating a decrease of crystallinity with the doping. The feasibility for use of these electrodes as ion storage for electrochromic devices was investigated. (C) 2003 Elsevier B.V. All rights reserved.