Co-doped CeO₂ catalyzes bidirectional sulfur redox reactions for high-performance lithium-sulfur batteries

To address the issue of slow kinetics in the sulfur reduction reaction/sulfur oxidation reaction in lithium-sulfur batteries (LSBs), in this work, cobalt was doped into CeO₂ composite carbon nanotubes by ion exchange as functional intercalation of LSBs. Cobalt doping enhances polysulfide trapping and ion/electron transport while activating adjacent Ce sites, thus improving the catalytic activity of the bifunctional catalytic process of polysulfides. The experimental results show that the incorporation of Co into CeO₂ induces the formation of oxygen vacancies, significantly reducing the lattice oxygen content and enhancing the catalytic performance. The material delivers an initial discharge capacity of 1285.6 mAh g^-1 at 0.2C and maintains a high specific capacity of 786.6 mAh g^-1 at 5C. The capacity decay rate is as low as 0.048% per cycle over 500 cycles at 3C. It is worth noting that under a high sulfur areal loading of 4.2 mg cm^-2, the capacity remained at 3.1 mAh cm^-2 after 100 cycles at 0.1C.