Lattice‐Oxygen‐Stabilized Li‐ and Mn‐Rich Cathodes with Sub‐Micrometer Particles by Modifying the Excess‐Li Distribution

Abstract In recent years, Li‐ and Mn‐rich layered oxides (LMRs) have been vigorously explored as promising cathodes for next‐generation, Li‐ion batteries due to their high specific energy. Nevertheless, their actual implementation is still far from a reality since the trade‐off relationship between the particle size and chemical reversibility prevents LMRs from achieving a satisfactory, industrial energy density. To solve this material dilemma, herein, a novel morphological and structural design is introduced to Li 1.11 Mn 0.49 Ni 0.29 Co 0.11 O 2 , reporting a sub‐micrometer‐level LMR with a relatively delocalized, excess‐Li system. This system exhibits an ultrahigh energy density of 2880 Wh L −1 and a long‐lasting cycle retention of 83.1% after the 100th cycle for 45 °C full‐cell cycling, despite its practical electrode conditions. This outstanding electrochemical performance is a result of greater lattice‐oxygen stability in the delocalized excess‐Li system because of the low amount of highly oxidized oxygen ions. Geometric dispersion of the labile oxygen ions effectively suppresses oxygen evolution from the lattice when delithiated, eradicating the rapid energy degradation in a practical cell system.