Thermodynamic study of WO3 and WO3:Li+ thin films

There is a considerable interest in the research and development of materials and devices that can be used for optical switching of large-scale glazings. Several potential switching technologies are available for glazings, including those based on electrochromic, thermochromic and photochromic phenomena. One of the most promising technologies for optical switching devices is the electrochromism (EC). In order to improve the electrochromic properties of tungsten oxide we have investigated the effect of lithium insertion on the electrochromic behavior of oxide films prepared by the sol–gel process.The kinetics and thermodynamics of electrochemical intercalation of lithium into LixWO3 and Lix(WO3:Li) films prepared by the sol–gel process were investigated. The standard Gibbs energy for lithium intercalation was calculated. The chemical diffusion coefficients, D, of lithium intercalation into oxide were measured by galvanostatic intermittent titration technique (GITT) as functions of the depth of lithium intercalation.