Zn Ionophores to Suppress Hydrogen Evolution and Promote Uniform Zn Deposition in Aqueous Zn Batteries

Uncontrolled Zn dendrites and undesirable side reactions such as Zn self-corrosion and hydrogen evolution reaction (HER) remain major challenges for the further development of aqueous Zn batteries (AZBs). In this study, macrolide antibiotics are proposed to be added to aqueous electrolyte, serving as Zn ionophores to modulate Zn2+ solvation structure, regulate Zn electrodeposition, and suppress undesirable parasitic reactions. Azithromycin (Azi), a representative macrolide antibiotic, is demonstrated to undergo bidentate coordination with Zn ions and remodel the solvation structure into [ZnAzi(H2O)(4)](2+). Meanwhile, the self-corrosion and HER at the Zn anode side are significantly suppressed, evidenced quantitatively by the on-line hydrogen production monitoring. Furthermore, the promotion of dense and uniform Zn electrodeposition by the ionophores is also confirmed. The repeated Zn plating/stripping test with 0.1 m Azi in electrolyte reaches a high cumulative capacity of 10 Ah cm(-2) at a current density of 10 mA cm(-2) and an area capacity of 10 mAh cm(-2). Moreover, the corresponding Zn-V2O5 pouch cell achieves stable operation for 100 cycles without bulging caused by gas evolution. Thus, the electrolyte engineering approach presents a practically viable strategy for the development of AZBs.