| 초록 |
Although lithium sulfur (Li-S) batteries get a lot of attention for high theoretical energy density and low cost of sulfur, the Li-S batteries suffer from poor gravimetric and volumetric capacity and low cycle stability because of low conversion of polysulfides and their shuttling, and high amount of conductive carbon. To address these issues, we present mesoporous carbon spheres and iron single atom catalysts (Fe-N-C) synthesized into the carbon spheres. High pore volume (3.5 cm3 g-1) facilitates the high accommodation of sulfur and spherical shape with controlled size enhances the packing of carbon and sulfur composites, which enable high volumetric energy density. Furthermore, Fe-N-C catalysts embedded in mesopores accelerate the conversion of polysulfides into insoluble lithium sulfide and adsorb the soluble species. As a result, the Li-S battery with high loading sulfur electrode (5.2 mg cm-2) exhibits outstanding cycle lifespan and 84% retention of the initial capacity after 500 cycles at a 3 C rate |
