Comprehensive water regulation via nucleophilic aldehyde for stable zinc anodes

Abstract

The application of zinc anode in aqueous zinc-ion batteries (AZIBs) is severely impeded by dendrite growth and side reactions. In this study, trace furfural (FF) was introduced into zinc sulfate electrolyte as a nucleophilic ligand to achieve comprehensive water regulation, targeting both interfacial water and the solvated water of hydrated zinc ions. Experimental and theoretical analyses reveal that nucleophilic FF molecules enter the solvation sheath of zinc ions and replace active water molecules, thus suppressing hydrogen evolution. Furthermore, FF molecules induce a water-deficient electric double layer by preferentially adsorbing on the zinc surface, which not only inhibits anode corrosion but also refines zinc crystals, thereby achieving uniform zinc deposition. As a result, the symmetric Zn||Zn cell with FF-ZnSO₄ electrolyte exhibits an extended cycle life and maintains stable of over 2980 h at a current density of 0.5 mA cm⁻². Even at the ultra-high current density of 22 mA cm⁻², the voltage polarization is stable at 0.12 V, demonstrating excellent rate performance. The Zn||VPH-sol-V₂O₅ full cells also demonstrate superior capacity retention and rate performance, underscoring the practical potential of this strategy. This study highlights the regulation role of nucleophilic ligands in limiting water activity in aqueous zinc-ion batteries.