Anti-Corrosive Covalent Iodo-Thiadiazole Catalyst Enables Aqueous Zn─S Batteries with High Coulombic Efficiency.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 40820648.
- Also identified by DOI 10.1002/adma.202508570 and PMC identifier 12574616.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Aqueous 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 I<sub>3</sub> <sup>-</sup> 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 I<sub>3</sub> <sup>-</sup> 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<sup>-1</sup> after 700 cycles at 8 C. The CIM-based pouch cell demonstrates a high capacity of 1398 mAh g<sup>-1</sup> 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.