Lithium‐Induced Inverted Honeycomb‐Ordered Superlattice Enables Durable O3‐Type Sodium Oxide Cathodes

ABSTRACT O3‐type layered sodium transition‐metal oxides, such as NaNi 1/3 Fe 1/3 Mn 1/3 O 2 (NFM), suffer from detrimental phase transitions, irreversible oxygen release, and unstable interfaces during high‐voltage operation, which severely hinder their practical application. Herein, we report a lithium‐induced inverted honeycomb‐superlattice engineering strategy that constructs a layered‐superlattice composite structure within NFM, resulting in a locally distributed yet long‐range‐ordered inverted honeycomb superlattice. In this structure, the transition‐metal (TM)‐dominant columns occupy the centers of hexagonal motifs, surrounded by mixed Li/TM vertex sites. This distinctive superlattice rigidly anchors the transition‐metal slabs, strengthens TM–O covalency, and suppresses irreversible interlayer gliding. It further regulates the high‐voltage structural and redox evolution by enabling highly reversible anionic oxygen redox and introducing a reversible O1 intermediate phase during cycling. Concurrently, the in situ formed Li 3 PO 4 (LP) coating effectively suppresses side reactions, further improving interfacial stability. The resulting NFM@LP cathode delivers 94.0% capacity retention after 500 cycles at 4.5 V, and the NFM@LP||hard carbon pouch full cell maintains 95.5% capacity retention over 200 cycles within 2.0–4.2 V. This work demonstrates that lithium‐induced inverted honeycomb superlattice engineering provides a promising design strategy for constructing high‐energy and durable O3‐type sodium cathodes.