Elucidating the Role of Intralayer Cation Ordering and Disordering in Li _0.6 [Li _0.2 Mn _0.8 ]O ₂ Cathode Materials

ABSTRACT Full‐manganese (Mn) Li‐rich materials have gained attention owing to the limited availability of cobalt‐ or nickel‐based cathodes commonly used in batteries, which greatly restricts their potential for large‐scale application. However, their practical implementation is hindered by the rapid voltage/capacity decay during cycling and the long‐standing problem of redox kinetics due to their poor ionic conductivity based on the ordered honeycomb structure. In this study, the kinetic and thermodynamic properties of intralayer disordered and ordered Li‐rich full‐Mn‐based cathode materials were compared, demonstrating that the disordered Li _0.6 [Li _0.2 Mn _0.8 ]O ₂ (D‐LMO) delivers a significant advantage of rate capability over the ordered Li _0.6 [Li _0.2 Mn _0.8 ]O ₂ (O‐LMO). Meanwhile, the D‐LMO keeps superior capacity retention of up to 99% after 50 cycles under 25 mA g ⁻¹ . In comparsion, the capacity retention of the O‐LMO drops to just 70%, and its average discharge voltage is 0.2 V lower than that of the D‐LMO. Herein, we conducted systematic density functional theory (DFT) simulations, focusing on the electronic structure modulation governing the voltage platform between the ordered and disordered phases. The ab initio molecular dynamics (AIMD) results indicated that the energy of the intralayer disordered structure fluctuates around the equilibrium position without any abrupt drops, demonstrating excellent stability. This study enhances the understanding of intralayer disordered full‐Mn Li‐rich material and provides insights into the design of low‐cost, high‐performance cathode materials for Li‐ion batteries.