Interfacial Engineering of N-Doped Carbon Host via Pore and Oxygen Coregulation for Superior Zinc-Iodine Batteries

Aqueous zinc-iodine batteries (AZIBs) are promising for grid-scale energy storage yet face challenges of polyiodide shuttling and sluggish kinetics in the iodine cathode. Nitrogen-doped porous carbons are widely used as host materials to mitigate these issues. However, the potential roles of different nitrogen configurations and their synergy with trace oxygen doping in the iodine conversion process remain unclear. Herein, a hierarchical N/O codoped porous carbon (ONC) is synthesized through a simple citrate-assisted pyrolysis method and utilized as an advanced host. The codoping strategy modulates the electronic structure of the carbon surface, significantly enhancing the chemical adsorption and catalytic conversion of iodine species, while the multi-scale pores provide effective confinement. This synergy, combined with abundant surface defects, reduces the charge transfer barrier and facilitates ion transport, resulting in rapid surface conversion kinetics. Consequently, the ONC/I₂ cathodes deliver a high capacity of 205.8 mAh g-¹ at 0.1 A g-¹ and excellent stability, retaining 59% of their initial capacity over 10,000 cycles at 1 A g-¹. This work provides deep insights into the synergistic mechanisms of heteroatom codoping in carbon hosts, guiding the rational design of high-performance iodine cathodes through the integration of pore engineering and interfacial chemistry.