Suppressing Side Reaction and Dendritic Growth via Interfacial Cyclization Molecule for Stable Zn Metal Anodes

Aqueous zinc battery has low cost, environmental friendliness, and safety, making it a promising candidate for next-generation battery systems. However, the Zn metal anode is impeded by a notorious dendrite growth and severe interfacial side reactions. Herein, a dendrite-free deposition mechanism based on an interfacial cyclization molecular layer is proposed, which enables dendrite-free Zn plating and lowers electrolyte corrosion by introducing trace methionine (Met) into the electrolyte. Different from normal acid-based additives, the Met can undergo cyclization via electrostatic interactions between amino and carboxyl groups, absorbing on the Zn electrode surface and forming an interfacial molecular layer, which can not only effectively remove the active H₂O molecules from the electrode surface but can also regulate the solvated structure and Zn²⁺-flux distribution at the interface, thereby suppressing dendritic Zn growth and side reactions. Thus, the Zn|Cu cells display a high Coulombic efficiency of >99.4% over 700 cycles at a current density of 1.0 mA cm^–2. Zn∥Zn symmetrical cells can also maintain a low overpotential over 2600 h at a current density of 1 mA cm^–2. Besides, the full cells with V₂O₅ cathode exhibit a long cycling life and high capacity retention (>60.6% after 1000 cycles at 0.5 A g^–1). We believe such an interfacial cyclization mechanism can offer an avenue to design stable electrodes/electrolytes and may also be expanded to other battery chemistries.