Single-Molecule Multifunctional Additive Enables Coupled Solvation and Interphase Engineering for Highly Reversible Zinc Anodes.

Dendritic formation and parasitic interfacial reactions occurring on the zinc anode remains a major obstacle to the commercialization of aqueous zinc-ion batteries. Rational electrolyte additive design offers an effective route to move beyond single-function regulation toward synergistic multimechanism control. Compared to multicomponent systems, single-molecule additives with multiple functional groups enable integrated control over solvation structure and interfacial chemistry while reducing complexity and cost. Herein, the natural amino acid hydroxyproline (hyp) is introduced as a multifunctional electrolyte additive for simultaneous regulation of the Zn2+ solvation and interfacial chemistry. The -COOH and -OH groups reconstruct the solvation sheath and hydrogen-bond network, while the -NH- group promotes interfacial adsorption and induces a compact, N-rich interphase that homogenizes Zn2+ flux and suppresses dendrite growth. Benefiting from this cooperative solvation-interphase regulation, stable Zn plating/stripping is achieved for over 2000 h in Zn//Zn cells, an average coulombic efficiency of 99.79% is maintained over 1500 cycles in Zn//Cu cells, and Zn//LiFePO4 full cells deliver a capacity of 154 mAh g-1 over 500 cycles at 0.2 A g-1. This work highlights single-molecule, multifunctional electrolyte additive engineering as a rational, scalable strategy for durable, safe aqueous zinc batteries.