Lithium intercalation in CeO2-TiO2 thin film

CeO2-TiO2 sol-gel thin coatings are known as transparent Li-ion storage electrode for electrochromic devices (ECD). As the charge capacity of the CeO2-TiO2 coatings is a limiting factor to get a high coloration intensity of such devices, the knowledge of transport kinetics parameters is of great importance to understand the behavior of this film during lithium insertion/extraction process. Aiming to understand better the lithium insertion behavior into CeO2-TiO2 film, a Galvanostatic Intermittent Titration Technique (GITT) and Electrochemical Impedance Spectroscopy ( EIS) were performed. The results obtained showed that the chemical diffusion coefficient D-Li increases with increasing of the lithium concentration ( x). The values approaching were 1.66 x 10(-13) cm(2)s(-1) at x = 0.03 and 2.14 x 10(-11) cm(2)s(-1) at x = 0.153. It was also observed from the Nyquist plot for the cerium-titanium electrode a Warburg-like dependence that can be associated to the semi-infinite diffusion through the oxide film.