Sub-nanometer cobalt clusters embedded carbon networks to promote the kinetics of polysulfide conversion

The sluggish oxidation-reduction kinetics of sulfur and the shuttle effect of polysulfides are the bottlenecks restricting the practical application of lithium-sulfur batteries. In this study, subnanometer cobalt clusters were embedded into the cross-linked network of carbon sheets framework as high-efficiency sulfur host materials to promote the kinetics of polysulfides conversion for lithium-sulfur batteries. In such composite structure, the carbon network provides a rapid electron transfer pathway for interfacial electrochemical reaction. Co and N atoms can chemisorb polysulfides by forming Co-S and Li-N bonds with polysulfides, and catalyze the conversion of polysulfides. Such structure exhibits excellent rate performance and cycle stability during the cycle of lithiumsulfur battery. The capacity decay rate per cycle is only 0.061% for 500 cycles at 1 C, and the capacity retention rate is 69.4%. The composite structure developed in this work is a promising and high-efficiency sulfur host for lithium-sulfur batteries.