Toward stable zinc metal anodes in aqueous zinc-ion batteries: a green and bifunctional electrolyte additive

Abstract

Aqueous zinc-ion batteries (AZIBs) are promising candidates for large-scale energy storage due to their high safety and low cost. However, the practical application of zinc metal anodes is hampered by parasitic reactions, including the hydrogen evolution reaction (HER) and dendrite growth. Herein, 4-chlorobenzenesulfonamide (CBS) is proposed as a novel and cost-effective electrolyte additive to achieve highly reversible zinc plating/stripping. Theoretical calculations and spectroscopic analyses reveal that the CBS molecules, featuring functional groups –SO₂₋ and –NH₂, effectively reconstruct the primary solvation sheath of Zn²⁺ by replacing water molecules, thereby reducing free water activity and suppressing the HER. Simultaneously, CBS preferentially adsorbs on the Zn surface, facilitating the formation of a robust solid electrolyte interphase (SEI) rich in ZnS, which guides uniform Zn deposition and inhibits dendrite formation. Consequently, the Zn∥Zn symmetric cell with the CBS-containing electrolyte achieves an ultralong cycling life of over 3000 hours at 0.25 mA cm⁻² and 0.25 mAh cm⁻². When paired with a MnO₂ cathode, the full cell exhibits significantly enhanced cycling stability, retaining a capacity of 95.91 mAh g⁻¹ after 600 cycles at 1 A g⁻¹. This work provides a strategic approach to stabilizing zinc anodes through rational electrolyte engineering with multifunctional additives.