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.