Insight into the Effect of Iodine Doping Soft Carbon and Iodine Functional Separator for Lithium‐Sulfur Batteries

Abstract Doping carbonaceous materials are regarded as prospective cathode candidates for high‐performance lithium‐sulfur (Li−S) batteries. In this study, we construct a dual functional modification system, including iodine‐doped soft carbon (I‐SC) and iodine functional separator for Li−S batteries. The formation of C−I bonds in the carbon skeleton increases the carbon interlayer spacing and displays a powerful chemical adsorption ability and electrocatalytic activity for polysulfide conversion. In addition, semi‐hollow micro‐rods‐structure soft carbon not only accommodates the volume expansion of sulfur, but also provides a continuous conductive network to transport Li + and electrons over cycling. Furthermore, by assisting with polyiodide (e. g., I 3 − and I 5 − ) modified separator, the polysulfide migration can be further controlled, resulting in a high capacity of 956 mAh g −1 at 0.2 C after 300 cycles. This work represents the importance of I‐doping and provides the potential of soft carbon for low‐cost and scalable fabrication of energy storage systems.