Tunable pore structure for confining polysulfides in high performance Li-S battery with coal precursor

The lithium-sulfur (Li-S) battery is a promising technology for next generation energy storage systems due to low cost materials and high theoretical energy capacity. However, the well-known 'shuttle effect' of polysulfides, that has significant impact on battery performance, has impeded the commercialization of Li-S batteries with high volumetric energy density and cycle life necessary for economic viability. Herein, we provide a facile method for the fabrication of hierarchical porous carbon with optimal pore structure to support sulfur in the cathode. The specific surface area of the coal-derived hierarchical porous carbon can be as high as 3343 m2/g, with a high distribution of pores between 2 and 5 nm, which is both beneficial to confining the polysulfides and increased sulfur loading (as high as 76 wt%). With most of sulfur confined in small mesopores, the carbon/sulfur composites show a high specific capacity of 1390 mAh/g at 0.05 C with ∼85% capacity retention after 100 cycles at 0.5 C.