Formulating long-cycle and high-rate lithium-rich manganese-based cathodes by surface-modification strategy coupling defect-engineering

Triggering the anionic redox reactions at high voltage is an effective approach to boost the capacity of Li-rich layered oxides. However, the irreversible lattice oxygen release at high voltage and sluggish ion kinetics remain conundrums. Herein, a surface modifying coupling defect engineering strategy is proposed to improve the reversibility of anionic redox reactions and ion diffusion efficiency in Li-rich layered oxides. A LiNbO₃ surface modification acts as an effective physical barrier to suppress lattice oxygen release, thereby improving cycling stability of Li-rich layered oxide. Furthermore, the oxygen vacancies in the LiNbO₃ coating enhance the ion transport kinetics, strengthening the rate capability. After 500 cycles, a high capacity retention of 83.3% can be achieved for the obtained cathode materials (the oxygen-deficient LiNbO₃-coated Li-rich layered oxide (CV-LLO)) at 5 C, much higher than that of the pristine materials (LLO, 52.3%). Moreover, CV-LLO delivers a capacity of 169.9 mAh·g⁻¹ at 5 C, which was 65.1% of the capacity at 0.2 C, much higher than that of the pristine LLO (85.6 mAh·g⁻¹, 33.7%). This study provides insights into the construction of Li-rich layered oxide cathode with highly reversible anionic redox reaction and highly cycling stability for Lithium storage.