All‐solid‐state sodium metal batteries paired with solid polymer electrolytes (SPEs) are considered a promising candidate for high energy‐density, low‐cost, and high‐safety energy storage systems. However, the low ionic conductivity and inferior interfacial stability with Na metal anode of SPEs severely hinder their practical applications. Herein, an anion‐trapping 3D fiber network enhanced polymer electrolyte (ATFPE) is developed by infusing poly(ethylene oxide) matrix into an electrostatic spun fiber framework loading with an orderly arranged metal‐organic framework (MOF). The 3D continuous channel provides a fast Na+ transport path leading to high ionic conductivity, and simultaneously the rich coordinated unsaturated cation sites exposed on MOF can effectively trap anions, thus regulating Na+ concentration distribution for constructing stable electrolyte/Na anode interface. Based on such advantages, the ATFPE exhibits high ionic conductivity and considerable Na+ transference number, as well as enhanced interfacial stability. Consequently, Na/Na symmetric cells using this ATFPE possess cyclability over 600 h at 0.1 mA cm−2 without discernable Na dendrites. Cooperated with Na3V2(PO4)3 cathode, the all‐solid‐state sodium metal batteries (ASSMBs) demonstrate significantly improved rate and cycle performances, delivering a high discharge capacity of 117.5 mAh g−1 under 0.1 C and rendering high capacity retention of 78.2% after 1000 cycles even at 1 C.

Sodium iron hexacyanoferrate (FeHCF) is one of the most promising cathode materials for sodium‐ion batteries (SIBs) due to its low cost theoretical capacity. However, the low electrochemical activity of FeLS(C) in FeHCF drags down its practical capacity and potential plateau. Herein, FeHCF with high FeLS(C) electrochemical activity (C‐FeHCF) is synthesized via a facile citric acid‐assisted solvothermal method. As the cathode of SIBs, C‐FeHCF shows superior cycling stability (ca. 87.3% capacity retention for 1000 cycles at 10 C) and outstanding rate performance (ca. 68.5% capacity retention at 50 C). Importantly, the contribution of FeLS(C) to the whole capacity was quantitatively analyzed via combining dQ/dV and discharge curve for the first time, and the index reaches 44.53% for C‐FeHCF, close to the theoretical value. In‐situ X‐ray diffraction proves the structure stability of C‐FeHCF during charge–discharge process, ensuring its superior cycling performance. Furthermore, the application feasibility of the C‐FeHCF cathode in quasi‐solid SIBs is also evaluated. The quasi‐solid SIBs with the C‐FeHCF cathode exhibit excellent electrochemical performance, delivering an initial discharge capacity of 106.5 mAh g−1 at 5 C and high capacity retention of 89.8% over 1200 cycles. This work opens new insights into the design and development of advanced cathode materials for SIBs and the beyond.

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Dendritic deposition and side reactions have been long‐standing interfacial challenges of Zn anode, which have prevented the development of practical aqueous zinc‐based batteries. Herein, an oxygen vacancy‐rich CeO2 aerogel (VAG‐Ce) interface layer that simultaneously integrates Zn2+ selectivity, porosity, and is lightweight is reported as a new strategy to achieve dendrite‐free and corrosion‐free Zn anodes. The well‐defined and uniform nanochannels of VAG‐Ce can act as ion sieves that redistribute Zn2+ at the Zn anode surface by regulating Zn2+ flux, leading to uniform Zn deposition and significantly suppressing dendrite growth. Importantly, the abundant oxygen vacancies exposed on VAG‐Ce surface can strongly capture SO42−, forming a negatively charged layer that can attract Zn2+ and accelerate the Zn2+ migration kinetics, while the subsequent repulsion of additional anions can effectively suppress the generation of (Zn4SO4(OH)6·xH2O) byproducts, thereby realizing very stable Zn anodes. Consequently, VAG‐Ce modified Zn anode (VAG‐Ce@Zn) enables a long‐term lifespan over 4000 h at 4 mA cm−2 and a record‐high cycle life of 1200 h is achieved under an ultrahigh 85% Zn utilization at 8 mA cm−2, which enables excellent capacity retention and cycling performance of VAG@Zn/MnO2 cells. This work contributes an innovative design concept by introducing oxygen vacancy‐rich aerogels and provides a new horizon for stabilizing Zn anode for large‐scale energy storage.

Sodium metal batteries (SMBs) using gel polymer electrolytes (GPEs) with high theoretical capacity and low production cost are regarded as a promising candidate for high energy‐density batteries. However, the inherent flammability of GPEs and uncontrolled Na dendrite caused by inferior mechanical properties and interfacial stability hinder their practical applications. Herein, an anion‐trapping fireproof composite gel electrolyte (AT‐FCGE) is designed through a chemical grafting–coupling strategy, where functionalized boron nitride nanosheets (M‐BNNs) used as both nanosized crosslinker and anion capturer are coupled with poly(ethylene glycol)diacrylate in poly(vinylidene fluoride‐co‐hexafluoropropylene) matrix, to expedite Na+ transport and suppress dendrite growth. Experimental and calculation studies suggest that the anion‐trapping effect of M‐BNNs with abundant Lewis‐acid sites can promote the dissociation of salts, thus remarkably improving the ionic conductivity and Na+ transference number. Meanwhile, the formation of highly crosslinked semi‐interpenetrating network can effectively in situ encapsulate non‐flammable phosphate without sacrificing the mechanical properties. Consequently, the resulting AT‐FCGE shows significantly enhanced Na+ conductivity, mechanical properties, and excellent interfacial stability. The AT‐FCGE enables a long‐cycle stability dendrite‐free Na/Na symmetric cell, and prominent electrochemical performance is demonstrated in solid‐state SMBs. The approach provides a broader promise for the great potential of fire‐retardant gel electrolytes in high‐performance SMBs and the beyond.

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