Interface adsorption enabled Ah-scale aqueous zinc-ion batteries

Abstract

Aqueous zinc-ion batteries (AZIBs) hold great potential for large-scale energy storage but are hindered by the limited reversibility of the Zn anode due to parasitic side reactions and uncontrolled dendrite growth. This study introduces ethylene diamine tetraacetic acid (EDTA) as an additive in aqueous electrolyte to lower the solvating capacity of water and promote anion coordination around Zn ions, thus accelerating desolvation kinetics. Stepwise theoretical calculations reveal that EDTA anion preferentially adsorbs on the Zn anode, effectively reshaping the electric double layer (EDL). Quantitative analysis using the Poisson−Boltzmann equation further demonstrates that the adsorption-type anionic additive increases Zn ion number concentration, reduces concentration polarization, and inhibits side reactions on the electrode surface, thereby enhancing charge transfer efficiency and optimizing the reaction process. With the addition of EDTA, Zn−V₂O₅ full cells with high mass loading (above 8 mg cm⁻²) exhibit improved self-discharge suppression, rate performance, and cycle performance. Notably, a successful transition from coin cells to larger-scale batteries has been demonstrated with a 1.21 Ah-scale pouch cell at the loading of 20 mg cm⁻².