First-principles study on the structural, electronic, and Li-ion mobility properties of anti-perovskite superionic conductor Li3OCl (100) surface

Surface properties play an important role in the application of antiperovskite Li3OCl as a promising solid-state electrolyte in all-solid-state Li-metal batteries. In this paper, we systematically investigated the stability, geometric structure, electronic properties and Li-ion mobility of a Li3OCl (1 0 0) surface using first-principles density functional theory calculations. Several geometric structure models were considered with different low Miller indices to obtain the most stable surface structure. The surface energies revealed that the Li3OCl (1 0 0) surface with Li- and Cl-termination on both sides was the most stable configuration, and the stability of the configuration was further verified by calculating the atomic relaxation and electronic properties. In addition, four types of point defects in the Li3OCl (1 0 0) surface were considered to study the Li-ion mobilities on the surface, and the results from calculating the defect formation energies and migration energy barriers showed that interstitial Li with a migration energy barrier of 0.086 eV is the most important carrier at the surface. The results provide fundamental insights into Li3OCl surface properties and Li-ion mobility at the surface.