Regulating non-bonding oxygen orbitals via high-entropy design for stable anionic redox

Abstract Sodium-ion batteries present a promising alternative to lithium-ion systems in specific applications owing to advantages in safety and cost. However, their energy density remains a key limitation. Anionic redox in oxygen offers a pathway to boost capacity in layered oxide cathodes, yet it often induces irreversible oxygen release and structural degradation at high voltages. Here, we introduce a high-entropy P3-type cathode, Na 0.67 Mn 0.75 Fe 0.05 Ti 0.033 Sn 0.057 Mg 0.017 Cr 0.043 -Zn 0.05 O 2 (HE-NMO), where multi-element transition-metal mixing effectively regulates the non-bonding oxygen orbitals involved in anionic redox. This entropy-mediated regulation disperses the non-bonding O 2p orbitals, stabilizing localized electron holes generated during oxygen oxidation and suppressing irreversible O–O dimerization and oxygen release. HE-NMO exhibits a discharge capacity of 166.6 mAh g −1 and a retention of 86.1% after 50 cycles at 2 C under high-voltage operation. Our work establishes high-entropy design as an effective paradigm for controlling anionic redox at the orbital level, advancing high-energy, durable sodium-ion batteries.