Mechanistic Insights into the Phase-Dependent Electrochemical Properties of Li3N

Li3N is a promising candidate for rechargeable lithium batteries owing to its high lithium-ion conductivity and excellent compatibility with lithium metal, yet the mechanisms behind the different electrochemical performance of α (P6/mmm) and β (P63/mmc) phases remain insufficiently understood. Accordingly, this study investigates the structure–property relationship of Li3N. Rietveld refinement based on neutron diffraction, together with bond-valence site energy (BVSE) analysis, reveals that variations in crystal parameters between α-Li3N and β-Li3N influence Li+ transport and that the two phases exhibit distinct migration pathways with different energy barriers. Density functional theory (DFT) calculations further show that vacancy formation energy influences the activation energies of the migration pathways and reveal the differences in the electronic structures between α-Li3N and β-Li3N. These findings provide mechanistic insights into the role of crystal structure in determining the electrochemical performance of Li3N, offering guidance for the design of advanced lithium ionic conductors.