Temperature dependence of kinetic behaviour of sol-gel deposited electrochromics

The kinetic behaviour of sol-gel deposited electrochromic films is affected by temperature in a complex manner and may be modelled by considering the reaction mechanism, and in particular, the rate-limiting steps. If assumptions are made about the rate-limiting steps in a reaction, a model may be formed which can be used to provide information about the kinetic parameters such as diffusion coefficient and charge transfer resistance. Changes in the free energy of a reaction are observed as changes in the electrical potential associated with the cells and electrodes. We have measured changes in the switching characteristics of a sol-gel deposited electrochromic film and modelled these results in order to extract information about the change in lithium chemical diffusion coefficient (D) with temperature. Values of D estimated using the model described in this paper are in close agreement with those determined by other means, however there are some anomalies at high temperatures. (C) 2001 Elsevier Science B.V. All rights reserved.