p-p orbital hybridization enables durable aqueous zinc-iodine batteries

Aqueous zinc-iodine batteries (AZIBs) are attractive for safe and low-cost energy storage yet are hindered by sluggish iodine redox kinetics and severe polyiodide shuttling. While single-atom catalysts (SACs) based on d -block transition metals have been extensively explored, their limited orbital directionality constrains performance. Herein, we propose an orbital-engineering strategy using p -block elements to enable effective p - p orbital hybridization and enhanced electronic coupling. Bi SACs anchored on N-doped porous carbons (Bi-NC) leverage their semi-metallic nature to induce effective Bi 6 p -I 5 p interactions, thereby accelerating iodine conversion and suppressing shuttling. The Bi-NC/I 2 cathode delivers 134.7 mAh g −1 with exceptional stability over 100,000 cycles at 16 A g −1 , exhibiting only 0.000141% decay per cycle. Furthermore, a Zn/Bi-NC/I 2 pouch cell achieves 1.07 mAh cm −2 and maintains 100% capacity retention after 200 cycles at 5 mA cm −2 . This work establishes p - p orbital hybridization as a powerful design principle for durable aqueous batteries.