Curvature engineering regulated of Mn-N4 moiety for high-performance aqueous zinc-iodine batteries

Aqueous zinc‑iodine batteries (AZIBs) are considered promising candidates for large-scale energy storage owing to their high theoretical energy density and intrinsic safety. However, the practical performance is severely limited by sluggish I 2 redox kinetics and the shuttle effect of soluble polyiodide. In this work, a curvature engineering strategy is developed for Mn-N 4 single-atom sites, in which the introduction of C I bonds induces a surface-contracted structure, leading to the formation of a Mn-NC-I configuration. This structural modulation breaks the geometric symmetry of the Mn-N 4 sites and redistributes the local electronic density, enabling directional halogen-bond interactions with polyiodide. As a result, I 2 are effectively anchored, polyiodide shuttling is suppressed, and the I 3 − /I − conversion kinetics are significantly accelerated. Benefiting from enhanced I 2 confinement, and catalytically active Mn centers, the Mn-NC-I/I 2 cathode delivers a high reversible capacity of 148.4 mAh g −1 at 0.1 A g −1 , excellent rate capability, and an ultralow capacity decay rate of 0.0016% per cycle over 20,000 cycles at 10 A g −1 . This study elucidates the critical role of curvature engineering in regulating Mn-N 4 mediated I 2 redox chemistry and provides a viable design principle for high-performance single-atom catalysts in AZIBs.