The mechanism of easier desorption of Fe atoms on the (1 0 0) surface of LiFePO4 and FePO4

Different surface models are built to explain the desorption properties of Fe atoms in LiFePO4 and FePO4 structures based on density functional theory (DFT) computations. Analyses of the band structures describe the pristine LiFePO4 and FePO4 structures with semiconducting (0.67 eV) and metallic properties, respectively. The electronic properties of the different surfaces mainly arise from the contributions of O and Fe atoms. Calculations of desorption energies and electronic properties reveal that the (1 0 0) surfaces of LiFePO4 and FePO4 are most favourable for desorption of Fe atoms, while the (0 1 0) surface is less susceptible. In addition, the investigations of Fe atom desorption energy at different strains indicate that the applications of strain increase the tendency of Fe’s desorption on LiFePO4 (1 0 0) surface. This study presents a theoretical foundation for understanding the correlation between different surfaces and desorption of Fe atoms for the future applications of lithium ion battery.