Understanding the Two-Stage Interfacial Mass Transfer of Zn²⁺ Ions in Aqueous Zinc Batteries

Parasitic reactions, dendrite growth, and sluggish zinc-ion transport kinetics coherently deteriorate the reversibility and stability of zinc anodes in aqueous zinc-ion/metal batteries. Thus, the simultaneous regulation of zinc ions and water contents at the interface and facilitation of zinc-ion reaction kinetics are crucial for advancing the zinc anode. Herein, we establish a hydrophobic decoration with two-stage facilitation of zinc-ion transport using the high-entropy alloy (HEA) to achieve these goals. The zincophilicity of the alloy enriches zinc ions in the electric double layer (EDL), achieving the first-stage acceleration. Meanwhile, the widespread d-band centers of each element provide gradual coordination to zinc ions, establishing the second-stage facilitation. Combining with the hydrophobicity of both the HEA and carbon supports, water, the source of side reactions, is shielded from the interface. This zincophilic, hydrophobic, and gradually accelerating interface contributes to a stable and highly reversible zinc anode, as demonstrated by a lifespan over 4000 h in Zn||Zn cells, and a Coulombic efficiency of 99.69%. Meanwhile, practical application is confirmed by the superior capacity retention of 90.9% in Zn||PANi batteries. These results underscore the efficacy of the diversified d-band centers, supplementing a novel dimension for future design of commercial separators.