First‐Principles Study on the Electronic Properties and Mechanical Stabilities of Anion‐Cation Multiple‐Doped LiFePO4

Abstract

AbstractIn this paper, N, Nb composite doped lithium iron phosphate structure was constructed, and its thermodynamic stability, intercalation voltages, volume change rate, electronic structure properties, and mechanical properties were systematically investigated using the first principles. The results of formation energy demonstrate that the N and Nb composite doping system meets the thermodynamic stability requirements and can exist consistently. In the process of de‐lithium, the volume change rate of the anion‐cation hybrid doping system is significantly decreased, and the intercalation voltage is increased, which indicates that the doping makes the cycling performance and energy density of the material improved. A radical shift in the material's electronic structure after doping is conducive to the enhanced conductivity of lithium iron phosphate. Besides, studies on the elastic properties of materials demonstrated that both N and Nb doping inhibited the generation of microcracks and diminished the occurrence of shear deformation.