Study on the Influence of Mn and Cl Co-Doping on the Electrochemical and Mechanical Properties of LiFePO4: A First-Principles Investigation

In this study, a first-principles approach based on density-functional theory was used to systematically investigate the Mn and Cl co-doped LiFePO4 materials, such as thermodynamic stability, volume rate of change, embedding voltage, electronic structure properties and mechanical properties. The findings imply that the formation energy of the doped system is low and meets the requirement of thermodynamic stability. The volume rate of change of the doped system is significantly reduced throughout the de-lithiation process and the embedding voltage increases slightly, which indicates that the introduction of dopant atoms can improve the cycling performance and energy density of the system. In addition, the introduction of Mn and Cl atoms leads to the emergence of impurity energy levels, which narrows the band gap of the system and increases the conductivity. The impact of doping on the mechanical stability of the materials was evaluated by calculating the elastic constants, and the results show that the co-doping of Mn and Cl greatly improves the ductility of the material, minimizes the possibility of shear deformation, and prevents microcracking.