Ab initio prediction for the ionic conduction of lithium in [formula omitted] and [formula omitted] olivine materials

Abstract

In this paper, olivine-type LiInSiO 4 and LiInGeO 4 as fast ionic conductors are predicted by ab initio density functional studies. The nudged elastic band approach showed extremely small energy barrier for lithium ion hopping to neighboring sites with 0.23 eV for LiInGeO 4 and 0.36 eV for LiInSiO 4. However, formation energy for the intrinsic defects including lithium ion vacancy sites is expected to be large (more than ∼1.5 eV), which suppresses ionic conductivity severely. Therefore it is expected that doping these olivine-type materials with higher valent cations may be a better option to create lithium ion vacancies.