Synergistic surface adsorption and pH regulation enable highly reversible zinc metal anodes

Aqueous zinc-ion batteries (AZIBs) stand out for their exceptional safety, and longevity, making them a highly promising candidate for energy storage systems. However, the application of AZIBs is hindered by detrimental side reactions and dendrite growth on the Zn-metal anode. To address this, a low-cost 2-Morpholinoethanesulfonic acid (MES) additive is introduced to improve the interfacial stability of Zn electrode. MES with highly electronegative sulfonic acid groups exhibits preferential adsorption on Zn surface and functions as a barrier against water ingress, thereby enhancing Zn²⁺ migration kinetics, and regulating interfacial current density and ion concentration distribution. Furthermore, the sulfonic acid groups with their pH buffering capability scavenge generated OH⁻, thus inhibiting the formation of insulated byproducts and promoting charge transfer kinetics. Consequently, the fabricated Zn//Zn cells deliver an impressive cycling life of 1000 h at 10 mA cm⁻²/5 mAh cm⁻². Even under a high capacity of 20 mAh cm⁻² and 68.3 % depth of discharge, the Zn//Zn cell maintains stable reversibility for over 400 h. Leveraging the ability of MES to suppress side reactions and facilitate uniform dense Zn deposition, the vanadium-based full battery demonstrates an extensive 5000 cycles at 2 A g⁻¹ without capacity fade. Notably, the corresponding pouch cell with a low negative-to-positive electrode capacity ratio (N/P ratio) of 2.3 retains high capacity of 201.3 mAh g⁻¹ after 500 cycles. This work offers a cost-effective approach to electrolyte design and optimization of interfacial stability for durable zinc metal anodes. © 2025 Elsevier B.V. All rights are reserved, including those for text and data mining, AI training, and similar technologies.