Tailoring Native Defects and Zinc Impurities in Li4Ti5O12: Insights from First-Principles Study

We report first-principles density functional theory (DFT) studies of native defects and zinc impurities in Li4Ti5O12 as a promising anode material for rechargeable Li ion batteries. The defects are characterized by their formation energies, electronic properties, and geometrical structures. The Ti vacancy and the Li antisite as multiple acceptor defects in p-type samples are preferred under O-rich conditions, while the Ti interstitial and Ti antisite are energetically favorable under O-poor conditions. In Zn-doped LTO, substitutional Zn located at the 8a Li site is preferable to form under reducing conditions, which brings a feasible decrease in the TiO6 octahedral distortion and has a potential effect on the Li ion diffusion. For all native defects and Zn impurities, no localized states are found in the calculated band gap, and their formation energies are all sensitive to the atomic chemical potentials and Fermi energy, which provide insights on how to design a rational defect-controlled synthesis condition to enhance the LTOs electrochemical performance for targeted applications.