Janus Calix[6]Arene Dual‐Site Additive Enables Dendrite‐Free Aqueous Zn Batteries

ABSTRACT Aqueous zinc (Zn) metal batteries hold great promise as safe, low‐cost, and sustainable energy storage systems, but their performance is undermined by dendrite growth, hydrogen evolution, and interfacial corrosion. Here, we introduce p‐sulfonatocalix[6]arene (SC6A), a water‐soluble supramolecular macrocycle, as a Janus‐like electrolyte additive which modulates the Zn ²⁺ solvation sheath and regulates interfacial ion flux. SC6A features dual functional sites: anionic sulfonates that selectively anchor to the Zn surface and phenolic hydroxyls that coordinate with Zn ²⁺ to facilitate desolvation. This dual‐site cooperation enables suppression of side reactions, reduces hydrogen evolution reaction (HER), and guides uniform Zn nucleation along the (002) facet. As a result, Zn||Cu cells achieve highly reversible Zn plating/stripping with a Coulombic efficiency of 99.7% over 1300 cycles, while Zn||NH ₄ V ₄ O ₁₀ full cells maintain 89% capacity after 1500 cycles at practical loadings (7–8 mg cm ⁻² ). Demonstrates practical feasibility in pouch cells, with minimal gas ecolution. These findings establish a molecular‐level supramolecular design strategy for interfacial engineering, enabling long‐life aqueous Zn metal batteries.