Emerging Polyacrylamide-Based Hydrogels as Electrolytes for Stable and Dendrite-Free Zn Anodes: Challenges, Strategies, and Perspectives

Rechargeable zinc-based batteries (ZBBs) have attracted considerable attention for use in large-scale energy storage systems due to their inherent high safety, low cost, and environmental friendliness. However, the practical applicability of ZBBs is limited by challenges related to the anode—such as uncontrollable zinc dendritic growth, the hydrogen evolution reaction (HER), and corrosion—which lead to significant polarization, capacity degradation, and unsatisfactory Coulombic efficiency of the ZBBs. Polyacrylamide (PAM)-based hydrogels have emerged as promising electrolyte materials to address these challenges due to their superior mechanical properties, flexibility, high ionic conductivity, and structural designability. Considering the rapid increase in research attention regarding this topic, we comprehensively summarize recent progress in PAM-based hydrogels as electrolytes for ZBBs in this study. First, we discuss the key challenges associated with Zn anodes in ZBBs, together with corresponding optimization strategies. Next, we detail the fundamental structure, properties, and synthesis of PAM-based hydrogels. Then, the relationships among synthetic methods, nano/microstructures, and electrochemical properties are systematically reviewed and discussed. Finally, prospects for the rational design and application of PAM-based hydrogels in ZBBs are summarized.