Nitrogen Doping Improves the Immobilization and Catalytic Effects of Co₉S₈ in Li-S Batteries

Several critical issues, such as the shuttling effect and the sluggish reaction kinetics, exist in the design of high-performance lithium–sulfur (Li-S) batteries. Here, it is reported that nitrogen doping can simultaneously and significantly improve both the immobilization and catalyzation effects of Co ₉S ₈ nanoparticles in Li-S batteries. Combining the theoretical calculations with experimental investigations, it is revealed that nitrogen atoms can increase the binding energies between LiPSs and Co ₉S ₈, and as well as alleviate the sluggish kinetics of Li-S chemistry in the Li ₂S ₆ cathode. The same effects are also observed when adding N-Co ₉S ₈ nanoparticles into the commercial Li ₂S cathode (which has various intrinsic advantages, but unfortunately a high overpotential). A remarkable improvement in the battery performances in both cases is observed. The work brings heteroatom-doped Co ₉S ₈ to the attention of designing high-performance Li-S batteries. A fundamental understanding of the inhibition of LiPSs shuttle and the catalytic effect of Li ₂S in the newly developed system may encourage more effort along this interesting direction.