Protein Cage Inspired Bridge‐Island Effect Enables Low‐Temperature Targeted Self‐Assembly of Hierarchical Hollow Polyanionic Cathodes for Sodium‐Ion Batteries

Abstract Achieving targeted morphological control over polyanionic cathodes under mild conditions remains a critical challenge. Drawing inspiration from the self‐assembly of protein cages, we propose an ionic weaving strategy for the low‐temperature fabrication of hierarchical hollow Na 3 V 2 O 2 (PO 4 ) 2 F (NVOPF) cathodes. By introducing low‐cost monosodium glutamate as a template precursor, the derived glutamate species self‐assemble into hollow micellar soft templates under the coordination bridging of VO 2+ ions. Subsequently, PO 4 3– , Na + , and F – ions are electrostatically attracted to VO 2+ ‐anchored microdomains, triggering island‐like nucleation. The VO 2+ ‐mediated bridge‐island effect facilitates both the construction of microscale hollow soft templates and the localized nucleation of nanocrystals, thereby enabling micro/nano hierarchical hollow morphology control of NVOPF under mild conditions. Moreover, the self‐assembly mechanism underlying hollow soft template formation is systematically elucidated for the first time through a combination of soft matter probing techniques, including fluorescence microscopy and negative staining, supported by density functional theory calculations and all‐atom molecular dynamics simulations. The resulting NVOPF‐based cathode exhibits ultra‐stable high‐rate cycling and excellent low‐temperature durability. This work establishes a new paradigm that integrates supramolecular self‐assembly with metal‐ion coordination chemistry for the rational design of fast‐charging polyanionic cathode materials.