Regulating Zn ²⁺ Solvation Structure via Dual-Site Hydrogen-Bond Acceptors for Highly Reversible Aqueous Zinc-Ion Batteries

Aqueous Zn-ion batteries (AZIBs) are promising for large-scale energy storage due to their intrinsic safety and cost-effectiveness. However, challenges such as Zn dendrite growth and side reactions hinder their practical application. Here, we demonstrate the role of oxazole (Oxa) as a multifunctional electrolyte additive in enabling a stable Zn electrode. Due to the presence of heteroatoms (oxygen and nitrogen) in its ring, Oxa molecules can act as dual-site hydrogen-bond acceptors, reconfiguring the original hydrogen-bond network of the aqueous electrolyte and thus reducing the activity of water. Moreover, benefiting from the strong coordination interaction of Oxa with Zn2+, Oxa can competitively engage with the solvated structure of Zn2+ to further prevent side reactions. Additionally, the strong adsorption of Oxa on the Zn electrode surface effectively inhibits dendrite formation. As a result, the Zn electrode in the electrolyte containing just 3 vol % Oxa exhibits remarkable stability, cycling for over 5700 h at 1 mA cm–2 and 1 mAh cm–2, and high reversibility, achieving an average Coulombic efficiency of 99.75% for more than 2300 cycles. This study highlights a successful electrolyte optimization strategy for the development of advanced AZIBs.