Engineering Oxygen Vacancy Distribution for Enhanced Structural Stability in Lithium-Rich Manganese-Based Oxide Cathode Materials

Lithium-rich manganese-based oxides (LRMOs) exhibit high specific capacity exceeding 250 mAh g^-1, making them promising candidates for next-generation lithium-ion batteries. However, oxygen evolution during cycling destabilizes the crystal structure, leading to capacity fading. By precisely controlling the oxygen/nitrogen (O₂/N₂) ratio during sintering, this work achieves a significant reduction in bulk oxygen vacancy content and enhances lattice oxygen stability. The O50 sample sintered under 50%O₂/50%N₂ atmosphere ratio demonstrates exceptional performance with 96.7% capacity retention (216.5 mAh g^-1) after 300 cycles at 1 C rate (1 C = 200 mA g^-1). Remarkably, it maintains delivering 155.0 mAh g^-1 at 5 C and 133.2 mAh g^-1 at 10 C, showing superior rate capability. Structural characterization reveals this atmosphere-controlled sintering strategy simultaneously enhances bulk oxygen stability and surface oxygen vacancy generation, providing a simple yet effective strategy for the design of high-performance LRMOs.