Hydrogel Electrolytes for Zinc-Ion Batteries: Materials Design, Functional Strategies, and Future Perspectives

• Hydrogel electrolytes combine high ionic conductivity with mechanical robustness, effectively suppressing zinc dendrite growth and enhancing interfacial stability in zinc-ion batteries. • Design strategies encompass natural polymers, synthetic polymers, and composites, with tunable properties via electrolyte salts and functional additives. • Functional optimizations include anti-freezing, self-healing, thermal responsiveness, and biocompatibility, enabling operation under extreme conditions. • Future development focuses on green, safe, and multifunctional integrated optimization to overcome current challenges.