Synergistic interfacial chemistry enabled by a multifunctional zwitterionic additive for high performance aqueous zinc metal batteries

Aqueous zinc metal batteries (AZMBs) face challenges like dendrite growth, hydrogen evolution, and corrosion, hindering their practicality. This work introduces 3-(1-pyridinio)-1-propanesulfonate (NDSB), a cost-effective zwitterionic electrolyte additive, which resolves these issues through four synergistic mechanisms. Studies show NDSB preferentially adsorbs on Zn surfaces, displacing water to form a water-deficient electric double layer, suppressing parasitic reactions. It also modifies Zn²⁺ solvation by replacing bound water, reducing electrolyte decomposition. Furthermore, NDSB guides uniform Zn deposition via selective adsorption on the (002) crystal plane, preventing dendrites. Controlled NDSB decomposition generates a robust, inorganic-rich solid-electrolyte interphase (SEI), enhancing interfacial stability. These mechanisms collectively boost anode reversibility: symmetric cells achieve > 2500 h cycling stability, Zn||Cu cells deliver 933 cycles with 99.75 % Coulombic efficiency, and full cells with vanadium/organic cathodes exhibit superior cycling/rate performance. NDSB's multifunctionality addresses interfacial instability, water reactivity, and irregular deposition through molecular adsorption, solvation tuning, crystallographic control, and SEI engineering. This work highlights zwitterionic compounds as scalable, economical electrolyte modifiers, offering a unified strategy for stable AZMBs. The success of NDSB demonstrates how a single additive can harmonize diverse stabilization pathways, paving the way for practical next-generation energy storage with enhanced performance and broad applicability.