Biomimetic Zwitterionic Hydrogel Electrolyte Enables Highly Reversible Zn Anodes

ABSTRACT Zn‐based batteries are promising candidates for sustainable, large‐scale energy storage. However, their practical deployment is hindered by dendritic Zn growth, parasitic side reactions and sluggish interfacial Zn 2+ transport. Inspired by phospholipid membranes, we introduce a biomimetic zwitterionic hydrogel electrolyte (PAMC) to integrate 2‐methacryloyloxyethyl phosphorylcholine, polyacrylamide and trace acrylic acid into a mechanically robust network featuring strong electrode adhesion and hierarchical Zn 2+ pathways. The zwitterionic moieties regulate the primary Zn 2+ solvation structure by partially replacing water ligands, thereby reducing the desolvation energy barriers and homogenize Zn 2+ flux at the electrode interface. Consequently, PAMC delivers a high ionic conductivity of 44.94 mS cm −1 and a record Zn 2+ transference number of 0.75, enabling dendrite‐free Zn deposition and suppressed hydrogen evolution. Symmetric Zn||Zn cells exhibit stable cycling for over 2200 h, while Zn||Cu cells maintain highly reversible Zn plating/stripping for more than 2000 h. Furthermore, full cells with activated carbon, NaV 3 O 8 and I 2 cathodes demonstrate outstanding cycling stability and rate capability. When integrated with a perovskite solar cell, the Zn||I 2 battery achieves an overall conversion efficiency of 13.3%, representing the highest reported to date for this category. This biomimetic electrolyte design establishes a universal platform for highly reversible Zn anodes and sustainable energy‐storage systems.