Regulating Uniform Zinc Deposition via Covalently Tethered Imidazolium Cations in Polyacrylamide Hydrogel Electrolytes for Stable Aqueous Zinc Batteries

Aqueous zinc-ion batteries (AZIBs) are promising candidates for next-generation energy storage due to their intrinsic safety and low cost. However, the uncontrollable zinc dendrite growth and interfacial side reactions limit their cycling stability and practical application. Herein, we describe a poly(ionic liquid) hydrogel electrolyte that incorporates a positively charged imidazolium-based ionic liquid (VEMA) into a polyacrylamide (PAM) network to address these challenges. The VEIM+ cations in electrolyte play a multi-role: homogenizing the interfacial electric field, immobilizing SO42- anions through ion exchange, and optimizing Zn2+ transport behavior to establish a dynamic balance between deposition and mass transfer rates, thereby mitigating concentration polarization. Both theoretical and experimental investigations demonstrate that VEIM+ preferentially adsorbs onto the zinc surface, forming an electrostatic protective layer that blocks water molecules, suppresses parasitic side reactions, and guides uniform zinc deposition while inhibiting dendrite formation. The resulting Zn||Zn symmetric cell of VEMA-based electrolyte achieves stable cycling for 2800 h, and the Zn||Cu asymmetric cell attains an average CE of 99.3%. Furthermore, the Zn||V6O13 full cell retains 92.04% capacity after 4000 cycles at 5 A g-1. This work provides a simple yet effective strategy for developing stable zinc anodes in AZIBs and offers a promising pathway toward practical applications.