Impact of Stacking Faults and Li Substitution in LiMnO₃ (0 ≤ x ≤ 2) Structural Transformations upon Delithiation

Lithium-rich layered oxides appear in most roadmaps as next generation Li-ion cathode materials owing to their superior capacity. Within this family, Li₂MnO₃ represents the archetype material and is often taken as model compound to better understand the complex structural modifications occurring in the first charging cycle. In this work, density functional theory (DFT) calculations have been used to understand the impact of stacking faults in the structural transformations occurring in Li₂MnO₃ upon delithiation, which are found to hinder the phase transformations leading to structural degradation. The formation energies of both ideal and defective LiMnO₃ compositions and the analysis of the encountered ground states have been used to rationalize the predicted differences in terms of structural evolution. From the understanding of the origin in the O1 phase transformation, Mg substitution is proposed as alternative strategy to improve the structural stability in this family of materials.