Proline‐Zwitterion Mediated Competitive Interactions Enabling Robust, Antifreezing, and Dendrite‐Suppressing Hydrogel Electrolytes for Aqueous Zinc‐Ion Batteries

ABSTRACT Aqueous zinc‐ion batteries are promising for flexible energy storage; however, water‐related issues such as electrolyte decomposition, dendrite growth, and anode corrosion impede practical application. Although hydrogel electrolytes can suppress water activity and guide zinc‐ion transport to inhibit dendrites, achieving high strength, high conductivity, and low temperature tolerance together remains challenging. Inspired by natural cryoprotection, a competitive interaction strategy using natural proline is present to enhance the polyvinyl alcohol (PVA)/ZnSO 4 hydrogel electrolyte. The hydrogel is physically crosslinked by PVA crystallites and stabilized by noncovalent interactions among PVA, Zn 2+ , and proline, showing 0.9 MPa tensile strength and 403% elongation. Proline's zwitterionic groups compete with water molecules in zinc‐ion solvation, with a higher binding energy of 222.15 kcal/mol compared to 100.42 for water, enabling uniform Zn deposition and dendrite suppression. Zn||MnO 2 cells with this hydrogel retained 61% capacity after 200 cycles at 0.5 C, much better than the 32% with a liquid electrolyte. Proline also breaks the hydrogen bonding network of water, lowering the freezing point of the hydrogel to −27°C and maintaining 1.95 mS/cm conductivity at −20°C. The hydrogel allows flexible pouch cells to operate reliably under deformation and freezing conditions, demonstrating great potential for wearable energy storage. image