A high-power aqueous rechargeable Fe-I2 battery

Aqueous Fe-I2 rechargeable batteries are highly desirable for large-scale energy storage because of their intrinsic safety, cost effective, and wide abundance of iron and iodine. However, their development suffers from Fe dendrite growth and severe shuttle effect during cycling. Herein, we demonstrate a high-performance Fe-I2 rechargeable battery using metal iron as anode, iodine/hierarchically porous carbon composite as cathode and an eco-friendly aqueous electrolyte. The anode modified with ascorbic acid effectively suppresses the formation of iron dendrite, while the cathode doped with nitrogen greatly reduces the shuttle of iodine species. The battery operates a reversible redox reaction of FeI2/I2 pair with fast kinetics. A capacity ~190 ​mAh g-1 at current densities up to 5000 ​mA ​g-1 and excellent cycle stability of 100% after 550 cycles at 2000 ​mA ​g-1 are obtained. The battery achieves superior power density of ~1300 ​W ​kg-1 at 120 ​Wh kg-1 and high energy density of 130 ​Wh kg-1 at 356 ​W ​kg-1. Our study shows great promise for high-performance rechargeable batteries with low-cost, eco-friendliness and high safety.