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Zn metal anode suffers from dendrite issues and passive byproducts, which severely plagues the practical application of aqueous Zn metal batteries. Herein, a polyzwitterionic cross-linked double network hydrogel electrolyte composed of physical crosslinking (hyaluronic acid) and chemical crosslinking (synthetic zwitterionic monomer copolymerized with acrylamide) is introduced to overcome these obstacles. On the one hand, highly hydrophilic physical network provides an energy dissipation channel to buffer stress and builds a H2O-poor interface to avoid side reactions. On the other hand, the charged groups (sulfonic and imidazolyl) in chemical crosslinking structure build anion/cation transport channels to boost ions' kinetics migration and regulate the typical solvent structure [Zn(H2O)6]2+ to R-SO3− [Zn(H2O)4]2+, with uniform electric field distribution and significant resistance to dendrites and parasitic reactions. Based on the above functions, the symmetric zinc cell exhibits superior cycle stability for more than 420 h at a high current density of 5 mA·cm−2, and Zn∥MnO2 full cell has a reversible specific capacity of 150 mAh·g−1 after 1000 cycles at 2 C with this hydrogel electrolyte. Furthermore, the pouch cell delivers impressive flexibility and cyclability for energy-storage applications. [ABSTRACT FROM AUTHOR]

Gel‐polymer electrolyte (GPE) is a pragmatic choice for high‐safety sodium batteries but still plagued by interfacial compatibility with both cathode and anode simultaneously. Here, salt‐in‐polymer fibers with NaF salt inlaid in polylactide (PLA) fiber network was fabricated via electrospinning and subsequent in situ forming gel‐polymer electrolyte in liquid electrolytes. The obtained PLA‐NaF GPE achieves a high ion conductivity (2.50×10−3 S cm−1) and large Na+ transference number (0.75) at ambient temperature. Notably, the dissolution of NaF salt occupies solvents leading to concentrated‐electrolyte environment, which facilitates aggregates with increased anionic coordination (anion/Na+ >1). Aggregates with higher HOMO realize the preferential oxidation on the cathode so that inorganic‐rich and stable CEI covers cathode' surface, preventing particles' breakage and showing good compatibility with different cathodes (Na3V2(PO4)3, Na2+2xFe2‐x(SO4)3, Na0.72Ni0.32Mn0.68O2, NaTi2(PO4)3). While, passivated Na anode induced by the lower LUMO of aggregates, and the lower surface tension between Na anode and PLA‐NaF GPE interface, leading to the dendrites‐free Na anode. As a result, the assembled Na || Na3V2(PO4)3 cells display excellent electrochemical performance at all‐climate conditions. [ABSTRACT FROM AUTHOR]