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 Zn 2+ 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 Zn 2+ 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.