A First‐Principles Study of Anion Doping in LiFePO4 Cathode Materials for Li‐Ion Batteries

Doping anions into LiFePO₄ can improve the electrochemical performance of lithium-ion batteries. In this study, structures, electronic properties and Li-ion migration of anion (F^- , Cl^- , and S^2- ) doping into LiFePO₄ were systematically investigated by means of density functional theory calculations. Anion substitution for oxygen atoms leads to an expansion of the LiFePO₄ lattice, significantly facilitating Li-ion diffusion. For Cl^- and F^- anion doped into LiFePO₄ , the energy barrier of Li-ion migration gets lowered to 0.209 eV and 0.283 eV from 0.572 eV. The introduction of anions narrows the forbidden band of LiFePO₄ , enhancing its electronic conductivity. This work pays a way towards the rational design of high-performance lithium-ion batteries.