Design Principles, Interfacial Regulation, and AI-Guided Opportunities of Hydrogel Electrolytes for Zinc Metal Batteries in Extreme Conditions

Abstract

Hydrogel-based zinc metal batteries (ZMBs) represent a highly promising platform for safe, flexible, and wearable energy storage systems. Nevertheless, their real-world application is greatly hindered by insufficient stability under harsh environmental conditions. To overcome these bottlenecks, recent studies have developed a series of effective strategies: functional moieties are introduced to adjust hydrogen-bonding networks for improved low-temperature resistance; thermally stable and water-retaining structures are integrated to enhance high-temperature endurance; and dynamic polymer networks are designed to achieve excellent mechanical strength, autonomous self-healing, and homogeneous zinc deposition. Fine modulation of polymer-water interactions and ion-solvation structures can effectively inhibit side reactions, reduce ion transport energy barriers, expand electrochemical stability windows, and support stable operation at high voltages. In addition to molecular-level design, recent research has unveiled the critical effects of coupled thermalmechanical-electrochemical stresses on interfacial chemical evolution and long-term cycling reversibility. This review provides a systematic overview of the underlying mechanisms, performance improvement approaches, and rational design principles of extreme-environment-adaptable hydrogel electrolytes, with emphasis on antifreeze properties, high-temperature stability, mechanical robustness, self-healing behavior, and high-voltage compatibility. Furthermore, this work highlights underexplored emerging directions, such as AI-driven optimization of polymer frameworks and electrolyte solvation structures, together with practical industrial concerns including scalable preparation and operational stability under realistic fluctuating conditions. Finally, integrated perspectives are put forward to guide the rational development of multifunctional hydrogel electrolytes, paving the way for durable and reliable next-generation zinc metal batteries capable of operating under extreme conditions.