Zincophilic Vertically Aligned Hydrogel Electrolyte With Enhanced Ion Transport and Dendrite Suppression for Stable Zinc-Ion Batteries

Abstract

Hydrogel electrolytes have emerged as promising candidates for flexible zinc-ion batteries (ZIBs) owing to their intrinsic mechanical robustness and biocompatibility. However, realizing high electrochemical performance and long-term operational stability remains a significant challenge, primarily due to the low ionic conductivity of hydrogel matrices and the uncontrolled growth of zinc dendrites, along with parasitic side reactions at the zinc anode interface. In this work, we propose a vertically aligned, zincophilic porous polyacrylamide-based hydrogel electrolyte (o-PAM) featuring strong interfacial adhesion. The unique structure, characterized by a locally alternating gel–liquid phase distribution, effectively overcomes the limitations of conventional hydrogel electrolytes by facilitating rapid Zn²⁺ transport and ensuring uniform ion deposition. This design bridges the ionic conductivity gap between gels and liquid electrolytes while mitigating Zn²⁺ concentration gradients. Moreover, the incorporation of multifunctional lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) into the hydrogel not only enhances the electrolyte–anode interfacial adhesion, thereby lowering interfacial resistance, but also contributes to electrochemical stability. The abundant hydrogen bond acceptors in LiTFSI interact with water molecules to form hydrogen bonds, reducing the activity of free water and effectively suppressing side reactions such as hydrogen evolution (HER). As a result, the o-PAM hydrogel electrolyte delivers a high Zn²⁺ transference number of 0.65 and an impressive ionic conductivity of 20.14 mS cm⁻¹. In Zn||o-PAM||Zn symmetric cells, the electrolyte demonstrates outstanding cycling stability, with a lifespan of 3000 h at 1 mA cm⁻². Furthermore, a full Zn||o-PAM||I₂ cell exhibits remarkable capacity retention of 95.4% after 500 cycles at 1 mA cm⁻². These results highlight a promising strategy for the rational design of high-performance hydrogel electrolytes for next-generation zinc-ion batteries.

Keywords

aqueous zinc-ion batteries / dendrite suppression / hydrogel electrolyte / interfacial stability / oriented porous structure

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2026 The Author(s). Carbon Neutralization published by Wenzhou University and John Wiley & Sons Australia, Ltd.