Cobalt nanoparticles embedded into free-standing carbon nanofibers as catalyst for room-temperature sodium-sulfur batteries

Room-temperature sodium-sulfur (RT Na-S) batteries are seriously limited because of poor conductivity of sulfur and sluggish reaction kinetics of polysulfide intermediates. Here, we design a free-standing film, constructed from Co nanoparticles onto nitrogen-doped porous carbon nanofibers (Co@NPCNFs), to load sulfur for RT Na-S batteries. Experiment result shows that Co as catalyst can enable the rapid sodium intercalation and fast reduction reaction of the polysulfides during cycling. Hence, the prepared Co@NPCNFs/S cathode exhibits a remarkable capacity of 906 mAh g-1 at 0.1 C and long cycling life up to 800 cycles with a slow capacity decay of 0.038% per cycle at 1 C.