Sugar additive with a halogen group enabling a highly reversible and dendrite-free Zn anode

Abstract

Aqueous zinc-ion batteries (AZBs) suffer from poor reversibility and limited lifespan due to parasitic side reactions and dendrite growth induced by active water. Although additives are widely used to address these issues by reducing the water content within the Zn-ion solvation sheaths, the strong interaction between the additives and Zn²⁺ causes poor de-solvation kinetics. Here, we propose a strategy that introduces an electron-withdrawing halogen group to reduce the polarity of the sugar additive. Theoretical simulations and experimental results demonstrate that a sucralose additive with optimal polarity can decrease the coordinated active water without hindering the de-solvation kinetics of Zn²⁺. This effectively regulates the overpotential and inhibits side reactions. Meanwhile, the additive can adsorb onto the surface of the Zn metal to modify the direction of zinc deposition and suppress dendrite growth. As a result, the Zn//Zn symmetric cell with the sucralose electrolyte additive exhibits an outstanding cycling life of 2400 h at a current density of 1 mA cm⁻². Moreover, when coupled with the V₂O₅ cathode, the full battery also demonstrates excellent operational stability, achieving 4000 cycles with a retained capacity of 51.84%.