Simultaneous Manipulation of Anions and Water Molecules by Lewis Acid–Base for Highly Stable Zn Anodes

Abstract

In aqueous zinc-ion batteries (ZIBs), Zn anodes often suffer from Zn dendrite and hydrogen evolution reaction (HER) in traditional electrolytes. Herein, fumed silica with both Lewis acid–base functional groups were introduced into traditional electrolytes. Owing to the strong Lewis acid–base interactions between Si─O─Si functional groups and SO₄²⁻ ions, the Zn²⁺ ion transference number is significantly increased in electrolyte, and thus more Zn²⁺ ions reach the Zn anode surface. As a result, the distribution of Zn²⁺ ions will be more homogeneous and dendrites growth will be suppressed on the Zn anode surface. In addition, Si─OH functional groups on fumed silica can also constrain the free and solvated H₂O molecules in electrolyte simultaneously through Lewis acid–base interactions between electronegative O atoms in Si─OH functional groups and electropositive H atoms in H₂O molecules, ensuring that the HER is inhibited on Zn anodes. Therefore, in the fumed silica-contained electrolyte, the Zn anodes exhibit a high reversibility and Zn||MnO₂ full batteries demonstrate a superior cycling performance.