Tailoring hydrogel electrolytes to enhance cathode performance in aqueous zinc-ion batteries

Aqueous zinc-ion batteries (AZIBs) have attracted considerable attention due to their intrinsic safety, high theoretical energy density, and low cost. However, the commonly used liquid electrolytes are frequently associated with cathode material dissolution, phase transition and structural collapse, which seriously hinder their practical application. The adoption of hydrogels as electrolytes can effectively isolate active materials from direct contact with free water, thereby suppressing cathode dissolution and byproduct generation. Meanwhile, the good mechanical stability of hydrogels helps alleviate volume changes in the cathode caused by Zn 2+ insertion/extraction. Despite notable progress in this field, there remains a lack of systematic guidelines for hydrogel electrolytes (HEs) tailored to enhance cathode performance. Based on the intrinsic properties of hydrogels, this review proposes design principles for cathode-oriented HEs and systematically summarizes corresponding preparation strategies. Finally, prospects for the future development of HEs tailored to enhance cathode performance are presented, with the aim of providing a theoretical foundation for the development of high-performance AZIBs and promoting further in-depth research in this field. • Systematic review of cathode-oriented hydrogel electrolyte design for aqueous zinc-ion batteries. • Core principles revealed: optimizing ion kinetics, stabilizing cathode interfaces, and regulating electrochemical reactions. • Comprehensive strategies: polymer selection, structural regulation, composite reinforcement, and electrode coupling. • Key challenges and future directions for practical application of high-performance aqueous zinc-ion batteries.