Terminating interfacial hydrogen-bond networks via preferential coordination for stable zinc metal anode

Aqueous zinc-ion batteries have emerged as promising candidates in next-generation energy storage systems. However, their practical implementation is significantly hindered by interfacial side reactions, particularly the hydrogen evolution reaction (HER) at the Zn metal anode interface. Herein, this study presents an innovative approach to address this challenge through the construction of an interfacial preferential coordination layer on the Zn anode surface. The proposed layer effectively terminates the continuity of interfacial hydrogen-bond networks and blocks proton transport, thereby mitigating the HER. Specifically, 2-phenylbenzimidazole-5-sulfonic acid (PBSA) with zincophilic groups was introduced as an electrolyte additive, which would be preferentially and selectively anchored on the Zn surface through its zincophilic nitrogen and sulfonic acid, forming the interfacial coordination layer. This coordination layer serves as a protective barrier, repelling water molecules from the Zn electrode surface and alleviating water decomposition. Crucially, the interfacial coordination layer features stronger hydrogen-bonding interactions with interfacial water molecules, terminates the hydrogen-bonding network between water molecules, hinders the transportation and electro-reduction of proton, and ultimately inhibits HER at the interface. As a result, the Zn symmetric cell with PBSA/ZnSO₄ delivered higher cycling stability of 2500 h at 1 mA cm⁻² and Zn//NH₄V₄O₁₀ full cells with PBSA/ZnSO₄ possessed enhanced capacity retention. This interfacial hydrogen-bond regulation strategy provided valuable insight for designing HER-free interfacial protective layer in high-performance aqueous batteries.