Enabling Highly Reversible Zn Anode by Multifunctional Synergistic Effects of Hybrid Solute Additives

Aqueous zinc ion batteries are promising secondary batteries for next-generation electrochemical energy storage. In this work, we report a hybrid electrolyte system with 3 M Zn(OTf)2 as zinc salt and 1 M urea + 0.3 M LiOAc as hybrid solute additives for highly reversible aqueous zinc ion batteries. In this electrolyte system, partial coordinated water molecules of Zn2+ are replaced, and the original hydrogen bond network of the bulk electrolyte also suffers from interruption. Moreover, the introduction of lithium acetate solves the aggravated self-corrosion caused by urea on the one hand and inhibits the growth of dendrites through the electrostatic shielding effect on the other. Benefiting from this multifunctional synergistic effect, dendrite-free Zn plating/stripping for 600 h at 4.8 mA cm–2 (20% depth of discharge) and highly reversible plating/stripping at ∼99.7% Coulombic efficiency with a high cumulative plating capacity of 1600 mAh is achieved.