Dual Dynamic Networks Enable a Bio‐Based Hydrogel Electrolyte With Simultaneous Robustness and Fast Zn ^{2 +} Transport for Highly Reversible Zinc Metal Batteries

ABSTRACT Zinc‐ion batteries (ZIBs) have become attractive candidates for large‐scale energy storage due to their inherent safety, eco‐friendliness, and low cost. Nevertheless, anode‐related issues such as Zn dendrites and side reactions hinder their practical applications. Herein, we report a functional bio‐based hydrogel electrolyte (denoted as SKG) featuring dual dynamic networks for highly reversible ZIBs. The strong hydrogen bond network introduced by glycerol within the sodium alginate (SA)/κ‐carrageenan (KC) matrix provides the mechanical robustness needed to physically suppress Zn dendrites. Moreover, the dynamic Zn ^{2 +} coordination networks constructed by the electronegative carboxyl (from SA) and sulfate (from KC) groups enable fast Zn ²⁺ transport kinetics and guided 3D diffusion, thus promoting uniform Zn deposition. Furthermore, the SKG electrolyte modulates the Zn ^{2 +} solvation structure, reducing the number of active water molecules and lowering the desolvation energy barrier to effectively suppress side reactions. Consequently, when coupled with the SKG electrolyte, the Zn anode demonstrates dendrite‐free deposition morphologies and highly reversible plating/stripping behaviors. Correspondingly, the Zn||NH ₄ V ₄ O ₁₀ full cell with the SKG electrolyte achieves outstanding rate performance and cycle stability. This study offers valuable insights for designing bio‐based hydrogel electrolytes toward high‐performance ZIBs.