Stabilizing Lattice Oxygen Redox via Thermally Driven La-Stratification for Ultra-Stable Li-Rich Cathodes

Lithium- and manganese-rich layered oxides (LMR) are promising cathodes for next-generation lithium-ion batteries owing to their high capacity and low cost. However, severe capacity fading and voltage decay caused by irreversible lattice-oxygen loss remain major obstacles to commercialization. Herein, a thermally driven stratification (TDS) strategy is developed to simultaneously construct a uniform La₂O₃ surface coating and a concentration-gradient La distribution in the bulk. Advanced characterization combined with DFT calculations reveals that bulk La stabilizes the chemical states of TMs and lattice oxygen, their local electronic structures and coordination environments, and the overall crystallographic framework, while enhancing Li⁺ diffusion kinetics. Meanwhile, the surface La₂O₃ layer promotes the formation of a stable cathode-electrolyte interphase and suppresses microcrack generation, thereby preserving structural integrity during cycling. As a result, the optimized LMR-TDS cathode delivers a high initial discharge capacity of 287.5 mAh g^-1 with an initial Coulombic efficiency of 88.50%, retains 90.37% of its capacity after 500 cycles at 1 C, and exhibits an ultralow voltage decay of only 0.967 mV per cycle. Furthermore, an LMR-TDS||graphite pouch cell achieves 84.67% capacity retention after 1000 cycles. This work provides an effective surface-bulk co-engineering strategy for simultaneously mitigating capacity fading and voltage decay in LMR cathodes.