First-principles study of native defects in LiTi2O4

Abstract

In this study, we report on a fundamental first-principles investigation of native point defects in spinel LiTi2O4, an alternative electrode material for lithium ion batteries (LIBs). Under O-rich conditions, Ti vacancy (VTi) and Li antisite (LiTi) are energetically favorable, but Ti interstitial (Tii) has highest formation energy and is hence unstable. While Li interstitial (Lii) is the most stable configuration in O-poor conditions, and O vacancy (VO), Ti interstitial (Tii), Li antisite (LiTi) and Ti antisite (TiLi) have almost the same formation energies, suggesting spontaneous formation of defect complexes. According to the calculated electronic structures of defects, no localized states are found in the gap between the O 2p and Ti t2g states, which is considerable related to the charge compensation process between O and Ti ions. Besides, Li vacancy (VLi) and Li interstitial (Lii) are the most stable defect types with negligible structural changes, while other defects will induce large octahedral disorders and suppress Li ions mobility. These results not only reveal the original defect information of LiTi2O4, but also provide practical guidance to the development of this material.