Entropy-Induced Lattice Stabilization and Interfacial Robustness in Li-Rich Mn-Based Layered Cathodes for High-Temperature Lithium-Ion Batteries

Li-rich Mn-based layered oxides (LRMOs) rely on lattice oxygen redox to achieve high energy density, but their high-temperature performance is limited by thermally accelerated oxygen loss and interfacial degradation. Here, it is verified that trace-level entropy-mediated doping (Mg, Cu, Ti, and La) exerts a dual role in LRMOs. At low doping levels, it stabilizes the bulk layered framework and interfacial chemistry via synergistic lattice regulation and transition-metal–oxygen (TM–O) covalency tuning. However, excessive doping suppresses lattice-oxygen redox activity and exacerbates electrochemical polarization, ultimately compromising reversible capacity and reaction kinetics. At an optimal dopant level of 0.25 at. % relative to total transition-metal content, the entropy-mediated doping suppresses Li/Ni disorder, expands lattice spacing, and enhances structural durability without sacrificing oxygen-redox reversibility. Consequently, Li1.2Mn0.5985Ni0.1995Mg0.0005Cu0.0005Ti0.0005La0.0005O2 delivers a high discharge capacity of 274.99 mAh g–1 at 0.1 C and sustains 227.18 mAh g–1 at 1 C. More importantly, it achieves 84.57% capacity retention after 100 cycles at 55 °C, substantially surpassing the unmodified LRMOs (58.10%). This work establishes trace-level entropy-mediated regulation of TM–O chemistry as a practical strategy for thermally robust, high-energy oxygen-redox cathodes.