Liu, J.Chen, Y.Wu, H.Ye, C.Qiao, S.-Z.2025-10-162025-10-162025Advanced Materials, 2025; 37(43):e08570-1-e08570-80935-96481521-4095https://hdl.handle.net/2440/147809Published online: August 18, 2025Aqueous zinc-sulfur batteries (AZSBs) hold great promise for large-scale energy storage but suffer from low Coulombic efficiency (CE) due to sluggish Zn─S redox kinetics and severe Zn anode corrosion, limiting their cycling life and practical applicability. Although state-of-the-art iodine-based redox mediators can accelerate cathode kinetics, they typically result in the formation of free I₃⁻ species, which exacerbate Zn corrosion. Here, we report a covalent iodo–thiadiazole redox mediator (CIM) as an anti-corrosive and highly efficient catalyst to achieve high CE in AZSBs. The covalently anchored iodine in CIM effectively suppresses free I₃⁻ formation and mitigates Zn corrosion. More importantly, dynamic electronic restructuring from C5═N to C5─N bonds (C5: 5th-position carbon in the thiadiazole ring) promotes Zn–S redox kinetics through a σ-coordination electron pathway facilitated by the Zn─I─C5 bond. As a result, CIM-based coin cells achieve an average CE of 99.56% and a capacity of 344 mAh g⁻¹ after 700 cycles at 8 C. The CIM-based pouch cell demonstrates a high capacity of 1398 mAh g⁻¹ after 120 cycles at 0.8 C. This work presents a practical design strategy for iodine-based catalysts, enabling next-generation aqueous metal-sulfur batteries with enhanced durability and performance.en© 2025 The Author(s). Advanced Materials published by Wiley-VCH GmbH. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.aqueous Zn─S batterieshigh coulombic efficiencyredox mediatorsZn anode corrosionZn─S redox intermediatesJournal article10.1002/adma.202508570747918Liu, J. [0000-0002-7777-312X]Chen, Y. [0000-0003-3579-0949]Wu, H. [0000-0002-5281-7325]Qiao, S.-Z. [0000-0002-1220-1761] [0000-0002-4568-8422]