Surface Anion Effects in Aqueous Hydrogen Ion Batteries

Aqueous hydrogen ion batteries possess the advantages of sustainability, low cost, and high safety, which makes them an ideal choice for grid-level energy storage. Although some anions show strong interaction with the surface of some metal oxides, the effect of anions on the cation intercalation behavior and electrochemical activity is rarely reported. Herein, we report that anions in the electrolyte can greatly affect the electrochemical performance of anatase TiO₂ in aqueous hydrogen ion batteries. The adsorption strength between the anatase TiO₂ (101) surface and the anions was found to follow the order of SO₄²⁻ > Cl⁻ > NO₃⁻. Experiments with theoretical calculations revealed that SO₄²⁻ can promote the electrochemical performance of the anatase TiO₂ anode for aqueous hydrogen ion batteries, while NO₃⁻ hinders the hydronium intercalation. This work can provide a new avenue for the design of high-performance aqueous batteries.