Computational screening of doping schemes for LiTi₂(PO₄)₃ as cathode coating materials

In all-solid-state lithium batteries, the impedance at the cathode/electrolyte interface shows close relationship with the cycle performance. Cathode coatings are helpful to reduce the impedance and increase the stability at the interface effectively. LiTi₂(PO₄)₃ (LTP), a fast ion conductor with high ionic conductivity approaching 10^-3 S·cm^-1, is adopted as the coating materials in this study. The crystal and electronic structures, as well as the Li⁺ ion migration properties are evaluated for LTP and its doped derivatives based on density functional theory (DFT) and bond valence (BV) method. Substituting part of Ti sites with element Mn, Fe, or Mg in LTP can improve the electronic conductivity of LTP while does not decrease its high ionic conductivity. In this way, the coating materials with both high ionic conductivities and electronic conductivities can be prepared for all-solid-state lithium batteries to improve the ion and electron transport properties at the interface.