Abstract: The poor reversibility and stability of Zn anodes greatly restrict the practical application of aqueous Zn-ion batteries (AZIBs), resulting from the uncontrollable dendrite growth and H₂O-induced side reactions during cycling. Electrolyte additive modification is considered one of the most effective and simplest methods for solving the aforementioned problems. Herein, the pyridine derivatives (PD) including 2,4-dihydroxypyridine (2,4-DHP), 2,3-dihydroxypyridine (2,3-DHP), and 2-hydroxypyrdine (2-DHP), were employed as novel electrolyte additives in ZnSO₄ electrolyte. Both density functional theory calculation and experimental findings demonstrated that the incorporation of PD additives into the electrolyte effectively modulates the solvation structure of hydrated Zn ions, thereby suppressing side reactions in AZIBs. Additionally, the adsorption of PD molecules on the zinc anode surface contributed to uniform Zn deposition and dendrite growth inhibition. Consequently, a 2,4-DHP-modified Zn/Zn symmetrical cell achieved an extremely long cyclic stability up to 5650 h at 1 mA cm^-2. Furthermore, the Zn/NH₄V₄O₁₀ full cell with 2,4-DHP-containing electrolyte exhibited an outstanding initial capacity of 204 mAh g^-1, with a notable capacity retention of 79 % after 1000 cycles at 5 A g^-1. Hence, this study expands the selection of electrolyte additives for AZIBs, and the working mechanism of PD additives provides new insights for electrolyte modification enabling highly reversible zinc anode.

Key words: Zn anode, Pyridine derivative, Electrolyte additive, Solvation regulation, Interface modification