Interfacial pH regulation by a tetra-hydroxyl organic additive enables stable zinc anodes in aqueous batteries

Abstract

A weakly alkaline tetra-hydroxyl organic molecule, ethylenediamine-N,N,N′,N′′-tetra-2-propanol, was introduced as an electrolyte additive in aqueous zinc-ion batteries. The organic molecules selectively adsorb on the zinc surface, where they effectively capture protons, buffer the local pH environment, and inhibit active water molecules. This mechanism suppresses parasitic side reactions and promotes uniform zinc deposition. As a result, the Zn‖Zn symmetric cell achieved stable cycling performance for over 860 hours at 0.5 mA cm⁻² and over 730 hours at 1 mA cm⁻². Furthermore, the full cell with the NH₄V₄O₁₀ cathode retained 84.2% of its capacity after 2000 cycles.