Triple-function of hydroxyacetone in suppressing water activity toward long-lived aqueous zinc-ion batteries

Abstract

Aqueous zinc-ion batteries (AZIBs) have shown great potential in the field of grid-level energy storage but are constrained by hydrogen evolution, corrosion and dendrite growth in the Zn anode. In this study, hydroxyacetone (HA), a polar molecule with multiple functional groups, is introduced as an electrolyte additive to address these problems. It is demonstrated that HA can regulate the solvation structures of Zn²⁺ by coordinating with Zn²⁺ through its polar functional groups, weaken the strong hydrogen bond network in water and form a water-poor inner Helmholtz plane (IHP) due to preferential adsorption on Zn surfaces. These effects inhibit water activity at the Zn anode and promote uniform Zn deposition along the (101) crystal plane, effectively suppressing parasitic reactions and dendrite growth. With HA-modified electrolyte, the Zn‖Zn symmetric cells show excellent cycling stability (>3200 h at 1 mA cm⁻², 0.5 mA h cm⁻²). The Zn‖Cu half-cell can also operate stably for 1500 cycles with a coulombic efficiency of 99.27% under the same conditions. The Zn‖MnO₂ full cell retains 78.74% of its initial capacity after 1600 cycles at 1 A g⁻¹. Meanwhile, the Zn‖MnO₂ pouch cell retains 80.83% of its capacity after more than 600 cycles, demonstrating outstanding application potential. These results indicate that HA as an additive has significant reference value in the practical application of AZIBs.