Hofmeister Effect-Induced Hydrogel Interphase Engineering for Highly Stable Zn Metal Anodes

The primary bottleneck restricting the commercialization of zinc batteries arises from the severe instability of the zinc anode interface, including uncontrolled dendrite growth and parasitic side reactions. Herein, this study presents a Hofmeister effect-regulated interfacial engineering strategy to synergistically stabilize zinc deposition and suppress side reactions. The introduction of kosmotropic anions induces ion-specific "salting-out" effects, driving interfacial ion enrichment and polymer chain reorganization to construct a compact hydrogel protective layer. This engineered interface enhances adhesion on 3D laser-textured Zn electrodes, suppresses hydrogen evolution via reduced water activity, and regulates Zn²⁺ transport through cooperative hydrophilic/hydrophobic microdomains, enabling homogeneous ion flux and deposition. The resulting optimized zinc anode exhibits an elevated hydrogen evolution overpotential and a significantly reduced corrosion current density (1.67 mA cm^-2). Zn||Zn symmetric cells with the LZ@gel anode deliver stable operation for over 4500 h at 1 mA cm^-2 and 1 mAh cm^-2, with negligible polarization evolution. In Zn||I₂ full cells, a high capacity of ∼198 mAh g^-1 is achieved, retaining 92.9% capacity retention even after 4500 cycles. Overall, the synergistic integration of Hofmeister-effect-regulated interfacial engineering and surface morphology optimization effectively mitigates kinetic limitations and suppresses dendrite formation, offering a robust strategy for durable, high-performance aqueous energy storage systems.