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

Abstract

AbstractAqueous 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.