Hydrogel electrolytes as dynamic ion-regulation platforms for safe and sustainable metal batteries

Dendritic zinc growth in aqueous zinc-ion batteries originates from coupled ionic-transport heterogeneity, concentration polarization, electric-field localization, and mechanically unstable electrode–electrolyte interfaces. Here, a three-dimensional electro-chemo-mechanical framework was developed to quantify how zeolite loading regulates these interconnected processes in polyacrylamide-based nanocomposite hydrogel electrolytes. The model integrates Zn²⁺ transport, electric-current conservation, Butler–Volmer kinetics, phase-field dendrite evolution, swelling, and solid mechanics using experimentally constrained composition-dependent properties. The PAM/15 wt% zeolite electrolyte provided the best baseline compromise, exhibiting an ionic conductivity of 13.48 mS cm⁻¹, an interfacial Zn²⁺ concentration of 0.74 mol L⁻¹, a maximum electric field of 1.18 × 10 5 V m⁻¹, and a current-density nonuniformity factor of 1.17. Its ionic-flux variance decreased to 2.61 × 10 − 12 , corresponding to a Flux Oscillation Index of 0.42, while the Mechanical Stability Index reached 0.91. Excessive loading at 20 wt% caused agglomeration, increased tortuosity, renewed transport heterogeneity, and localized stress despite greater bulk stiffness. Multilevel validation showed strong agreement with experimental transport, dendrite-growth, field, deformation, and cycling data. Sensitivity analysis identified current density as the dominant operating variable, whereas diffusivity, conductivity, tortuosity, and modulus governed distinct transport and mechanical responses. The predicted optimum shifted only between 12.9 and 16.2 wt%, confirming a robust intermediate-loading design window rather than a single universal composition.

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