Small-Molecule Sulfur Iodine Cathodes for Fast-Kinetic Lithium–Sulfur Batteries

Lithium–sulfur batteries (LSBs) hold great promise for next-generation energy storage due to their high theoretical energy density. However, their practical application is hindered by sluggish sulfur redox kinetics and the severe shuttle effect. In this work, a small-molecule sulfur–iodine (S–I) composite is physically confined within a porous carbon host, which not only enhances the electronic conductivity but also accelerates sulfur reaction kinetics and improves cycling stability by effectively suppressing polysulfide shuttling. Concurrently, the present work delivers a high specific capacity of 814 mAh g–1 with 80 wt % active material loading and demonstrate stable cycling over 250 cycles. Notably, even at an ultrahigh loading of 90 wt %, a substantial capacity of 530 mAh g–1 is retained. These results highlight the crucial role of porous carbon-confined small-molecule S–I cathodes in enhancing sulfur redox kinetics and cycling stability, offering a viable strategy for high-performance LSBs.