Interfacial adsorption-enabled trace additives for stable zinc-based flow batteries

Abstract

Aqueous zinc-based flow batteries (AZFBs) have emerged as a promising candidate for large-scale energy storage systems benefiting from their high theoretical capacity, environmental friendliness, and cost-effectiveness. Nevertheless, the practical application of AZFBs is still significantly impeded by the interfacial challenges including uncontrolled dendrite growth and the parasitic hydrogen evolution reaction (HER) at the zinc anode. To address these issues, we report 3-[bis(2-hydroxyethyl)amino]-2-hydroxy-propane sulphonic acid (DIPSO) as a bifunctional additive for anode interface engineering and promoting instantaneous zinc deposition. The sulfonic acid group and hydroxyl-rich structure of DIPSO help in reshaping the solvation structure of Zn(OH)₄²⁻, thereby suppressing the activity of water through hydrogen-bond interactions with water molecules. These groups facilitate preferential adsorption of DIPSO molecules on zinc surfaces to regulate nucleation sites, thereby affording uniform dendrite-free zinc deposition and enhancing Zn plating/stripping reversibility. As a result, prolonged cycling performance for nearly 300 cycles was demonstrated at 80 mA cm⁻² in the AZFBs with the regulation of the DIPSO additive. Meanwhile, the AZFBs with a high areal capacity of 80 mAh cm⁻² at 80 mA cm⁻² also achieved stable cycling for >200 h. The DIPSO-enabled anode configuration paves the way for durable, high-areal-capacity zinc-based energy storage systems.