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.