First-principles studies on cation point defects in LiTi2O4

Lattice defects are common in electrode materials and may affect their structural stability and electrochemical performance. Here we use first-principles calculations based on density functional theory to investigate native cation point defects in spinel LiTi2O4, a potential candidate for anode material in lithium ion batteries. We consider vacancies, interstitials, antisite defects, Frenkel defects and some defect pairs. Our calculations show that Li interstitial, Ti interstitial, Li Frenkel defect and Li antisite are low-energy defects, and thus they would be detectable in LiTi2O4, while cation vacancies and Ti Frenkel defect are hard to form due to their high formation energy. Binding energies are calculated to illustrate whether the isolated defects will clustering or not. In addition, the effect of native defects on migration of Li is studied. We find that Li antisites can make the migration barrier of Li interstitial decreasing significantly.