Lithium Diffusion Pathways in β-Li₂TiO₃: A Theoretical Study

In recent experimental studies based on NMR techniques, the ion dynamics in β-Li₂TiO₃ has been discussed controversially. In order to shed light on this discussion, Li ion diffusion processes in β-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 β-Li₂TiO₃ are calculated. According to our results, β-Li₂TiO₃ is a wide gap insulator with an indirect band gap at F-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.