Application Progress of hydrogels in aqueous zinc batteries

Aqueous zinc-ion batteries (AZIBs) have emerged as highly promising candidates for next-generation flexible energy storage, driven by the intrinsic safety, earth-abundance, low cost, and exceptional volumetric capacity of metallic zinc. However, the widespread application of traditional liquid AZIBs is severely hindered by parasitic reactions and dendrite formation at the zinc anode, which are triggered by highly reactive water molecules, ultimately degrading cycle stability. In this context, gel electrolytes can precisely regulate the chemical behavior of water, interfacial side reactions and zinc deposition morphology inside aqueous zinc-ion batteries through targeted structural design, making them a highly competitive solution. Furthermore,. replacing liquid systems, hydrogels offer unique advantages for flexible devices, including leak-proof characteristics, robust adhesion, high ionic conductivity, and superior cycling performance. Despite their immense potential, existing hydrogel electrolytes still suffer from inadequate mechanical properties, such as poor fatigue resistance and insufficient flexibility, which fall short of practical requirements. This review summarizes recent advances in network structure, surface, and additive modifications. These strategies have greatly boosted electrochemical performance and facilitated the deployment of such electrolytes in flexible electronics. Future research should focus on optimizing formulations to realize thinner electrolyte layers, developing multifunctional biopolymer matrices, and clarifying interfacial chemical evolution under extreme operating conditions so as to promote the practical application of AZIBs.