Multi-Dimensional Regulation of Zinc-Electrolyte Chemistry via a Dual-Functional Small-Molecule Polyol Additive

Abstract

Despite the immense potential of aqueous zinc-ion batteries (AZIBs) for grid-scale energy storage, their practical implementation is significantly throttled by the electrochemical instability of the Zn metal anode. Here, we report Butene Glycol (BG) as a highly efficient and multifunctional electrolyte additive that effectively stabilizes the zinc anode by regulating Zn2+ solvation and building a robust solid-electrolyte interphase (SEI). Spectroscopic characterization and theoretical calculations show that BG molecules enter the solvation sheath of Zn2+ by partially replacing water molecules via their hydroxyl groups, thereby restructuring the hydrogen-bond network in the bulk electrolyte. This suppresses water-induced side reactions and improves Zn2+ desolvation kinetics. Furthermore, a BG-derived ion-conductive SEI is constructed that concurrently inhibits corrosion, guides Zn2+ deposition preferentially on the (101) crystal plane, and suppresses dendritic Zn growth. Benefiting from these synergistic effects, Zn//Zn symmetric cells demonstrate steady cyclability for over 2400 h at low current densities (1 mA·cm-2, 1 mAh·cm-2), and for over 800 h at high current densities (5 mA·cm-2, 5 mAh·cm-2). The Cu//Zn cells maintain an average Coulombic efficiency of 99.7% even after 600 cycles. Moreover, the MnO//Zn full cells retain 85% of their initial capacity after 1000 cycles, with an average Coulombic efficiency as high as 99.8%.