(CeO2)(x)-(TiO2)(1-x): Counter electrode materials for lithium electrochromic devices

Since 1989, (CeO2)(x)-(TiO2)(1-x) have been considered as possible counter electrode materials for electrochromic devices using lithium conducting electrolytes and WO3 as electrochromic material. The electrochemical behaviour of thin films of these materials depends on the structure of the films and on the electrolyte composition. According to X-ray diffraction data, the films seemed to be composed of an amorphous matrix of TiO2 including nanocrystallites of CeO2. After a short review of the data previously obtained, new data obtained on materials made up by using either sol-gel processes (Ti(OPri)(4) + Ce(OPri)(4) or CeCl3 or Ce(NH4)(2)(NO3)(4)) or sputtered from oxide targets are presented. The influences of the nanocrystalline structure, of the electrolyte type (polymer based solid electrolyte or liquid organic electrolyte) and of the water content are discussed.