Diffusion of Li and Na ions in TiO2, anatase, was studied using theoretical (quantum chemical ab initio periodic Hartree-Fock and a modified semi-empirical INDO) as well as electrochemical (chronocoloumetry) methods. On the basis of the theoretical calculations, the geometry of equilibrium and transition states for the impurities as well as the crystalline framework were analyzed and discussed. The calculated activation energies for Li+- and Na+ diffusion were found to be only slightly higher than 0.5eV by both theoretical methods. The agreement of either theoretical method with the electrochemical experiments, 0.60 and 0.52eV for Li+ and Na+, respectively, was also remarkably good.

Li and Na Diffusion in TiO2 from Quantum Chemical Theory versus Electrochemical Experiment. Lunell, S., Stashans, A., Ojamäe, L., Lindström, H., Hagfeldt, A.: Journal of the American Chemical Society, 1997, 119[31], 7374-80