Abstract
Present paper suggests olivine-type LiInSiO4 and LiInGeO4 as candidate materials for fast Li ionic conductor predicted by ab initio density functional studies. The nudged elastic band approach showed extremely small energy barrier for Li ion hopping to neighboring sites with 0.23 eV for LiInGeO4 and 0.36 eV for LiInSiO4. However, formation energy for the intrinsic defects including Li vacancy sites is expected to be large (more than ~1.5 eV), which suppresses ionic conductivity severely. Therefore, doping strategy, i.e. introduction of higher valent cations into olivine structure, may required to create Li vacancy sites.
