Confining Acetonitrile-I2 Complexes via Fe Single-Atom Sites for Rapid and Reversible Iodine Redox Kinetics at −40°C

Abstract

To achieve rapid and reversible iodine redox kinetics under low-temperature conditions, we developed atomically dispersed Fe sites anchored on porous carbon (Fe-PC) that actively engage the confinement of acetonitrile-I2 charge-transfer complex, guiding them into an efficient liquid-liquid conversion pathway on the PC surface with a lowered reaction barrier. Consequently, at −40°C, the Fe-PC/I2 cathode exhibits exceptional capacity of 215.9 mAh g−1 at 1 C and impressively retains 133.0 mAh g−1 at 20 C. This work provides a viable route and fundamental insight for designing high-rate iodine batteries operating under subzero environments.