| Abstract Scope |
Li- and Mn-rich layered oxides (LMROs) are promising high-energy cathode materials enabled by combined cationic and anionic redox activity, yet their long-term electrochemical and structural evolution has been reported with considerable variability across the literature. In this work, we examine the origins of these discrepancies by systematically correlating long-term cycling behavior with changes in redox characteristics and crystal structure under well-controlled electrochemical conditions. Distinct electrochemical evolution modes are observed depending on the cycling environment, accompanied by gradual structural reorganization during extended operation. By integrating electrochemical analyses with advanced structural and spectroscopic characterization, we establish a unified mechanistic picture that rationalizes previously reported, seemingly divergent phase-evolution behaviors in LMROs. Our findings provide a general framework for interpreting long-term degradation phenomena in anion-redox-active cathodes and offer insights relevant to the design of more durable high-energy oxide materials. |