The diffusion pathways of Li+ ions within the frameworks of the high-conductivity solid electrolytes, Ti2Li(PO4)3 and Ti1.7Li1.3Al0.3(PO4)3, were determined by using molecular mechanics and molecular dynamics methods. From the potential energy profile for Li migration in Ti2Li(PO4)3, the barrier to Li migration was estimated to be 0.30eV. This value was in excellent agreement with experimental data. The main influence on the activation energy for Li diffusion arose from changes in the electrostatic interactions. Lengthy molecular dynamics simulations of Ti1.7Li1.3Al0.3(PO4)3 also confirmed the occurrence of solid-state diffusion via rare and sporadic hopping of Li+ ions from an energy minimum site to a neighboring energy minimum site.

Lithium Ion Migration Pathways in LiTi2(PO4)3 and Related Materials. G.Nuspl, T.Takeuchi, A.Weiss, H.Kageyama, K.Yoshizawa, T.Yamabe: Journal of Applied Physics, 1999, 86[10], 5484-91