Ultrastable Electrolytic Zn–I₂ Batteries Based on Nanocarbon Wrapped by Highly Efficient Single-Atom Fe-NC Iodine Catalysts

Aqueous Zn–iodine (Zn–I₂) conversion batteries with iodine redox chemistry suffers the severe polyiodide shuttling and sluggish redox kinetics, which impede the battery lifespan and rate capability. Herein, an ultrastable Zn–I₂ battery is introduced based on single-atom Fe–N–C encapsulated high-surface-area carbon (HC@FeNC) as the core–shell cathode materials, which accelerate the I⁻/I₃⁻/I° conversion significantly. The robust chemical–physical interaction between polyiodides and Fe–N₄ sites tightly binds the polyiodide ions and suppresses the polyiodide shuttling, thereby significantly enhancing the coulombic efficiency. As a result, the core–shell HC@FeNC cathode endows the electrolytic Zn–I₂ battery with an excellent capacity, remarkable rate capability, and an ultralong lifespan over 60 000 cycles. More importantly, a practical 253 Wh kg⁻¹ pouch cell shows good capacity retention of 84% after 100 cycles, underscoring its considerable potential for commercial Zn–I₂ batteries.