A Poor-Water Electric Double Layer Enabling a Highly Reversible Zinc Anode via Interfacial Adsorption of Heteroatom-Rich Organic Anions

Recently, aqueous zinc-ion batteries have been highly favored due to their high theoretical capacity, excellent safety performance, and relatively low cost; however, rampant dendritic growth on the surface of zinc metal anodes and inevitable side reactions closely related to the active H2O molecules at the electrode/electrolyte interface severely inhibit their practical applications. Herein, ampicillin sodium (Arb) is developed as an efficient electrolyte additive to construct a water-poor electric double layer (EDL) at the interface to address the aforementioned problems. It is found that the anion in the Arb preferentially adsorbs at the zinc anode/electrolyte interface through strong coordination capacity from heteroatoms (N and O) and charge characteristics, constructing a water-poor EDL to repel reactive H2O molecules, and thus suppressing water-induced side reactions and enabling uniform zinc deposition/stripping. Simultaneously, the electron-rich functional groups of Arb effectively reconfigure the hydrogen bonding network in the electrolyte and refine the solvation structure of Zn2+ to further prevent the occurrence of side reactions. Based on the unique reshaping of interfaces, solvation structures, and hydrogen bonding networks by Arb, the Zn//Zn symmetrical cell with the Arb-added electrolyte demonstrates over 2400 h of stable cycling at 1 mA cm–2, while the Zn//V6O13 full cell with the Arb-added electrolyte retains 92.86% capacity after 1000 cycles. This work offers a novel EDL design framework for stable zinc anodes.