Regulation of Oxygen Redox in Disordered Rock-Salt LiXO₂ Li-Ion Cathodes by Cation Effects: A First-Principles Study

The modulation of anionic redox reactions has been demonstrated to significantly enhance the performance of oxide cathode materials. To elucidate this phenomenon, we conducted comprehensive first-principles calculations on disordered rock-salt (DRX) cathode materials with simple stoichiometry, which have emerged as highly promising candidates due to their unique structural and compositional flexibility. Our comprehensive investigation combining qualitative evaluation of oxygen coordination environment, quantitative analysis of metal-oxygen electronic states, and systematic magnetic characterization reveals two anion redox mechanisms in DRX: the reversible reductive coupling mechanism and irreversible oxygen dimerization mechanism. A three-tier framework for categorizing cation redox behavior is established based on the extent of anion redox contribution: Cu and Ni strongly promote oxygen redox; Cr, Mn, Fe, and Co show moderate participation; while Ti, V, Zr, Nb, Mo, and W exhibit minimal involvement. Furthermore, by studying systems doped with multiple cations, we demonstrated that cationic effects could regulate oxygen redox behavior. These insights provide valuable guidance for the rational design of DRX cathode materials with enhanced performance and durability.