Computational Insights into Defect-Mediated Ion Transport in Li₂AOCl Antiperovskites as Potential Solid Electrolytes for Li-Ion Batteries.

Antiperovskite oxides such as Li₂AOCl (A = H, Na, K, …) are promising solid electrolytes due to their high intrinsic Li-ion conductivity and structural tunability. We present a systematic first-principles investigation of defect formation and Li-ion transport across this material family. Using density functional theory within supercell models, we calculate substitutional and vacancy formation energies to assess defect stability as a function of dopant charge and ionic radius. Bond-valence-sum mapping identifies likely Li-ion migration pathways, and climbing-image nudged-elastic-band (CI-NEB) calculations yield activation barriers and predicted ionic conductivities. Trends across different A-site substitutions reveal how lattice distortion and local bonding environments influence Li-ion mobility and structural stability. Together, these results provide a comprehensive framework linking defect chemistry to ionic transport, establishing design principles for tailoring Li-antiperovskite electrolytes and guiding experimental efforts toward high-conductivity solid electrolytes for next-generation Li-ion batteries.