Lithium Diffusion Pathways in β-Li2TiO3: A Theoretical Study

In recent experimental studies based on NMR techniques, the ion dynamics in beta-Li2TiO3 has been discussed controversially. In order to shed light on this discussion, Li ion diffusion processes in beta-Li2TiO3 are investigated theoretically using periodic quantum-chemical DFT methods. It is observed that Li+ migrates along the ab plane as well as in the direction perpendicular to the LiTi2 layers with the activation energies ranging between 0.44 and 0.54 eV, suggesting a slow ion dynamics. In addition, the structural, electronic, and defect properties and the electric field gradient (EFG) parameters at Li positions of beta-Li2TiO3 are calculated. According to our results, beta-Li2TiO3 is a wide gap insulator with an indirect band gap at Gamma-C. The calculated defect formation energy values as well as the EFG parameters show that there are three different Li sites in the structure, namely, Li(1), Li(2), and Li(3), which are in well accord with the experiment.