Tyrosine additives with rich-polar functional groups provide multi-protections for ultra-stable zinc metal anodes

The widespread commercialization of aqueous Zinc-Ion batteries (AZIBs) is severely limited by dendrite growth and rampant parasitic reactions. While various additives have been introduced to improve the stability of zinc anodes, a single polar functional group additive cannot provide comprehensive protection for zinc anodes. Here, a low-cost, high-functionality Tyrosine (Tyr) organic small molecule is utilized as an electrolyte additive to achieve ultra-stable zinc metal anodes. The findings indicated that the electronegative carboxyl group tended to participate in the solvation sheath of Zn²⁺. The zinc-philic amino group and hydrophobic benzene ring synergistically construct a hydrophobic electric double layer on the surface of the zinc anode. The hydrophilic nature of the hydroxyl group enables it to capture free water molecules and reconstruct the hydrogen bonding network of the electrolyte. More importantly, the strong adsorption of Tyr molecule is beneficial to induce the formation of an in-situ organic-inorganic hybrid solid electrolyte interface layer, thereby further enhancing protection for the zinc anode. Profiting from the synergistic effect of the polyfunctional group in the Tyr additive, the Zn||Zn cell exhibits ultra-long cycle stability over 3800 h (∼ 20 times vs. ZnSO₄) at 1.0 mA cm^‒2, 1 mAh cm^‒2 and an ultra-high cumulative plated capacity of 8.75 Ah cm^‒2 at 5.0 mA cm⁻². Furthermore, the Zn||Cu cell delivers a significantly improved reversibility with an average Coulomb efficiency of 99.88 % after 3000 cycles. This finely regulated electrolyte, leveraging the synergistic effects of multiple functional groups, heralds a promising trajectory for the advancement of enduring Zn metal batteries.