High configuration entropy P2-type Mn-based layered oxide with robust structure and wide-window cycling stability for sodium-ion batteries

Mn-based layered oxides have become competitive cathode materials for sodium-ion batteries (SIBs) due to their high energy density, cost-effectiveness, and potential for large-scale production. However, these materials often suffer from irreversible redox reactions, significant phase transitions, and the formation of microcracks, leading to substantial internal stress and subsequent degradation of their electrochemical performance. This study presents a high-entropy engineering strategy for P2-type manganese-based layered oxide cathodes, utilizing solid-state sintering to fabricate a Ni/Co-free high-entropy layered oxide, P2-Na 0.67 Mn 0.6 Cu 0.2 Li 0.075 Mg 0.025 Ti 0.025 Al 0.025 Sn 0.025 Zr 0.025 O 2 (high-entropy-doped layered oxides, HEO). It was found that the high configurational entropy significantly stabilized the layered framework and MnO 6 octahedral local structures, suppressing detrimental phase transitions during high-voltage cycling (>4.0 V) and enabling highly reversible cation/anion redox reactions. Benefiting from the high-entropy stabilization effect, complex atomic structure, and multi-element composition, these factors collectively improved the material's performance and stability. The HEO exhibits a capacity of 160.5 mAh g −1 at 0.1C within a wide voltage window of 2–4.5 V, demonstrating excellent cycling stability (with a capacity retention of 93.1 % after 100 cycles at 0.5C) and outstanding rate capability (94.8 mAh g −1 at 5C). Thus, this study expands the application of high-entropy layered materials, offering new insights for the design of high-stability sodium-ion battery cathodes.