Biomass-Derived N-Doped Porous Carbon With Enhanced Iodine Confinement for High Performance Aqueous Zinc–Iodine Batteries

Aqueous zinc–iodine (Zn−I₂) batteries have emerged as promising energy storage systems due to their high capacity, safety, and low cost, but their practical application is limited by high solubility, shuttle effect, and poor conductivity of iodine species. To overcome these challenges, porous carbon (PC) hosts with strong iodine affinity and sustainable origin are essential for enhancing iodine confinement and improving electrochemical performance. Herein, collagen-derived N-doped porous carbon (NPC) are successfully synthesized through simple carbonization and potassium hydroxide (KOH) activation processes, and utilized it as a host material for iodine in Zn–I₂ batteries. NPC exhibited a well-developed nanoporous structure with a significantly enhanced Brunauer–Emmett–Teller (BET) surface area of 2230 m² g⁻¹ and a pore volume of 1.1 cm³ g⁻¹, providing numerous active sites for effective iodine confinement. Consequently, electrochemical performance evaluations revealed exceptional rate capability (235 mA h g⁻¹ at 20 A g⁻¹) and remarkable cycling stability, retaining 246 mA h g⁻¹ after 5000 cycles at 6 A g⁻¹ with approximately 99.90% Coulombic efficiency. The enhanced electrochemical performance was attributed to synergistic effects between nanoporosity and nitrogen doping of NPC, effectively stabilizing iodine species and facilitating high-rate redox reactions. This study highlights the potential of sustainable collagen-derived NPC as an efficient cathode host material for advanced aqueous Zn−I₂ batteries.