Oxygen-anchoring high-entropy design boosting anionic redox reversibility in Li-rich layered cathodes

The irreversible oxygen redox (OR) in Li-rich layered cathodes leads to severe structural degradation and voltage decay, particularly under harsh operating conditions. Although high-entropy oxides (HEOs) offer enhanced stability compared to conventional doping modifications, rational element selection for optimizing OR reversibility remains unexplored. Here, we propose an entropy engineering design paradigm for “oxygen-anchoring”, where optimal cation electronegativity (>Mn, 1.55) and d (3 d /4 d )- p orbital hybridization synergistically enhance transition metal–oxygen (TM–O) covalency and stabilize the O 2 p state. Two high-entropy Li-rich layered oxides: Li 1.2 Mn 0.47 Ni 0.115 Co 0.115 Mg 0.02 Ti 0.02 Al 0.02 Nb 0.02 Mo 0.02 O 2 (MTANM) and Li 1.2 Mn 0.47 Ni 0.115 Co 0.115 Mg 0.02 Ti 0.02 Cu 0.02 Nb 0.02 Mo 0.02 O 2 (MTCNM) were synthesized using partial nano-scale precursors and comparatively evaluated. MTCNM exhibits enhanced electrochemical performance and superior oxygen stability compared to MTANM by replacing Al with higher-electronegativity Cu, which possesses improved orbital overlap with oxygen. Both experiments and density functional theory (DFT) calculations demonstrate that element selection changes the covalency of TM–O through altered electronegativity and d orbitals- p orbitals ( d - p ) hybridization. Further stepwise screening selected the optimal elemental combination Li 1.2 Mn 0.47 Ni 0.115 Co 0.115 Cr 0.02 Cu 0.02 Nb 0.02 Mo 0.02 Ru 0.02 O 2 (CCNMR), which achieved near 100% capacity retention after 150 cycles at 1 C, 50 °C, with its voltage decay effectively suppressed. This work establishes a rational element-screening paradigm for entropy-stabilized OR chemistry in high-energy cathodes.