Enhanced Oxygen Redox Reversibility and Structural Stability in Li2MnO3 Cathode Material via High-Entropy Stabilization

Li 2 MnO 3 , a cobalt- and nickel-free layered oxide material with high theoretical capacity, is a promising candidate for next-generation, cost-effective cathode materials in lithium-ion batteries. However, its practical application is hindered by severe irreversible phase transition from layered to spinel structure and oxygen loss, resulting in poor cycling performance. In this study, a high-entropy stabilized material, Li 1.0 Na 0.2 K 0.2 Mn 0.535 Zr 0.015 Cu 0.025 Mg 0.025 O 1.7 F 0.3 (HE-LMO), is developed to mitigate these issues. The high-entropy design effectively stabilizes the layered structure, suppresses the formation of Mn 3 O 4 , and reduces irreversible oxygen evolution. As a result, HE-LMO exhibits enhanced structural stability and delivers a specific capacity of ≈270 mAh g −1 after 20 cycles, attributed to the activation of reversible oxygen redox activity. Advanced characterization techniques, including X-ray absorption spectroscopy, in situ X-ray diffraction, and ex situ aberration-corrected scanning transmission electron microscopy, are employed to elucidate the impact of high-entropy stabilization on the material's performance. These findings highlight the effectiveness of high-entropy stabilization in improving lithium-rich manganese-based cathode materials, providing a novel strategy for developing low-cost, high-performance cathode materials for lithium-ion batteries.