Network-Anchored Nanocages Create Weakly Solvating Electrolytes for Subzero Aqueous Zinc Batteries

Low-temperature operation of aqueous zinc batteries is fundamentally limited by electrolyte freezing and sluggish interfacial kinetics, originating from strong ion-solvent interactions. Here, we report a steric-regulated weakly solvating hydrogel electrolyte enabled by network-anchored fluorinated Zr-based metal-organic polyhedra (MOPs). The rigid, hydrophobic nanocage architecture simultaneously anchors Zn²⁺ through coordination and sterically excludes active water molecules, thereby diluting the local electrostatic field, lowering the desolvation barrier, and disrupting extended hydrogen-bond networks to suppress ice crystallization. As a result, Zn||Zn symmetric cells cycle stably for over 3700 h at -40°C, while Zn||MnHCF full cells deliver 65.8 mAh g^-1 at -20°C with 82% capacity retention after 350 cycles, and still maintain 24.6 mAh g^-1 at -40°C. Spectroscopic, electrochemical, and theoretical analyses reveal that Zr-based MOPs reconstruct the Zn²⁺ solvation shell into a spatially expanded, weakly bound structure that accelerates charge transfer and suppresses parasitic reactions. This work establishes a steric-architecture design paradigm for engineering weakly solvating electrolytes, offering a robust strategy for aqueous batteries operating under extreme low-temperature conditions.