Organic Molecular Amino Acids Additives Containing Amide Groups for Uniform Zinc Deposition in Aqueous Zinc Ion Batteries

Aqueous Zn-metal batteries have been considered as a potentially sustainable energy storage device. They often suffer from poor reversibility and cyclability due to metallic Zn dendrites and parasitic reactions. However, the previous perspectives and mechanisms, coupled with their intricate functional groups for dendrite growth, H2 evolution, and Zn metal corrosion, render the selection criteria of electrolyte additives inherently ambiguous. Herein, it takes amino acids as an example and detailed explored the impact of three typical groups ─NH2, ─COOH, and ─CO─NH2. It is identified that the primary determinant of amide groups can be used as active sites to refine the Zn2+ ion solvation structure and promote Zn deposition. At the Zn metal-electrolyte interface, the chemisorption of amide onto the surface of the Zn anode inhibits hydrogen evolution and facilitates planar deposition of Zn. As a result, the Zn||Zn cell with optimal amino acids with amide group shows remarkable cycling durability under a current density of 10 mA cm-2. When combined with the NH4V4O10 cathode, the assembled coin cell retains ≈60% of its capacity after 500 cycles. This amino acids molecule additive, emphasize the role of amide group in fine-tuning Zn2+ solvation structures and Zn/electrolyte interface electrochemical properties.