Olivine-type LiInSiO4 and LiInGeO4 were predicted, by ab initio density functional studies, to be fast ionic conductors. The nudged elastic band approach indicated extremely small energy barriers for lithium ion hopping to neighbouring sites, with 0.23eV for LiInGeO4 and 0.36eV for LiInSiO4. However, the formation energy for the intrinsic defects including lithium ion vacancy sites was expected to be large (more than about 1.5eV), which severely suppressed ionic conductivity. Therefore it was expected that doping these olivine-type materials with higher-valence cations might be a better option to create lithium ion vacancies.

Ab initio Prediction for the Ionic Conduction of Lithium in LiInSiO4 and LiInGeO4 Olivine Materials. T.Rajkumar, M.Nakayama, M.Nogami: Solid State Communications, 2010, 150[15-16], 693-6