Zwitterionic Nanomicelle Self-Assembly Reconstructs Interfacial Chemistry toward Durable Zinc Anode

Abstract

The long-term durability of Zn metal anodes is severely compromised by interfacial instability, primarily stemming from uncontrolled dendrite growth and parasitic side reactions. Herein, sulfonated polybetaine (SPE), a zwitterionic surfactant bearing both hydrophobic long alkyl tail and hydrophilic charged headgroups, is utilized as functional electrolyte additive to drive the spontaneous self-assembly of stable, nanoscale micelles within conventional ZnSO4 aqueous electrolyte. These dynamic supramolecular structures reshape the anodic interface properties, rendering it adaptive to reversible Zn plating/stripping chemistry. Primarily, the preferentially adsorbed micelles onto Zn surface build a dynamic electrostatic shield that effectively homogenize the electric field and guide the uniform flux of Zn 2+ ions, thereby fundamentally suppressing the formation of Zn dendrites. Concurrently, the hydrophilic yet charge-neutral interface formed by the micelles significantly confines the reactivity of free water and related parasitic reactions, including hydrogen evolution and corrosion. Consequently, this micelle-assisted interface enables Zn||Zn symmetric cells to achieve exceptional cycling stability for over 3900 hours at 0.5 mA cm -2 , drastically outperforming the mere 200 hours observed with the bare electrolyte. Zn||Cu cells also witness a distinct average coulombic efficiency increase from 92.5% to 96.6%. This study underscores the great potential of organic-solvent-free micellar electrolytes in next-generation, durable aqueous metal batteries.