Emerging Advanced Design Strategies and Engineering toward Polymer-Hydrogel Electrolytes for Flexible Zinc-Based...

Aqueous zinc-based rechargeable batteries are promising candidates for intelligent energy storage solutions due to the low redox potential of the anode (-0.763 V vs SHE), the ultrahigh theoretical capacity of zinc (820 mA·h·g⁻¹), low cost, and exceptional safety. However, their integration with flexible electronic devices necessitates the exploitation of electrolytes that combine both flexibility and stability. Polymer-hydrogel, with unique features of both liquid-like ion transfer and solid-like mechanical robustness, and tunable physicochemical characteristics, can endow Zn-based batteries with extraordinary functional traits and provide a promising and optional solution for integration with other flexible electronic devices. Herein, the latest advances in the rational design of hydrogel electrolytes, focusing on geometric configuration, terminal group modification, and intermolecular interactions, are comprehensively reviewed. These strategies are carefully examined in the context of enhancing ionic conductivity, liquid retention, mechanical properties, and adaptability to extreme environments. This review highlights how these innovations enable zinc-based batteries to be ultrathin, bendable, twistable, stretchable, and self-healing, making them an ideal platform for integration with flexible electronics. By overcoming these hurdles, hydrogel electrolytes can significantly contribute to the advancement of flexible energy storage technologies, paving the way for their widespread application in next-generation electronic devices.