Redox Chemistry of a Lithium-Excess Disordered-Rocksalt Oxyfluoride Cathode: Li ₂ Mn _0.625 Nb _0.375 O ₂ F

High Resolution Image Download MS PowerPoint Slide In this work, by employing density functional theory (DFT) and ab initio molecular dynamics (AIMD) simulations, the Li-rich archetypal disordered-rocksalt oxyfluoride Li 2 Mn 0.625 Nb 0.375 O 2 F as a potential cathode material for lithium-ion batteries is carefully analyzed. To evaluate the delithiation effects on the structural properties, the evolution of the bond-length distribution around Mn atoms as well as the volume changes during the charging process are investigated. The assessment of the redox chemistry indicates that charge compensation is predominantly governed by the Mn 2+ /Mn 4+ double-electron redox couple, with only a minor contribution from oxygen redox. It has been found that partial substitution of O by F and the Li-rich environment lead to an energetic overlap between Mn and O redox activity at high states of charge. Moreover, AIMD simulations indicate local structural stability within the simulated timescales at both 300 and 900 K. This study provides a detailed mechanistic understanding of redox processes and delithiation-induced effects on structural properties in the proposed Li-rich disordered oxyfluoride and highlights this material as a promising high-capacity cathode material for lithium-ion batteries.