Cycle test and degradation analysis of WO3/PC+LiClO4/CeO2•TiO2 electrochromic device

We fabricated an electrochromic full cell device adopting WO3 as a working electrode, and 1 M LiClO4 in PC with 3% water addition as an electrolyte and CeO2 center dot TiO2 with various thicknesses as an ion storage layer. CeO2 center dot TiO2 with less than 100 nm shows large charge density but the long-term cyclability is not good due to lithium ion diffusion into ITO thin film. Therefore, the thickness of CeO2 center dot TiO2 ion storage layer should be coated at more than 200 mm/min. Long-term cycle test results show that CeO2 center dot TiO2 ion storage layer with more than 150 nm thickness and two time coating enhance the long-term stability. SIMS analysis results show that the degradation is due to the remaining lithium ion in the working electrode, WO3. (C) 2009 Elsevier B.V. All rights reserved.