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

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 SO₄ ^2- 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.