Boosting Li–S Battery Performance by Regulating\nMicrostructures of Porous Hollow Carbon Nanospheres from Lignites

Li–S\nbatteries with high energy density are considered to\nbe some of the most promising energy storage devices. However, the\nshuttle effect, sluggish kinetics, and volume expansion problems of\nlithium polysulfides (LiPSs) have severely limited their industrial\napplications. In this work, porous hollow carbon nanospheres (HCNSs)\nwith tunable microstructures were designed by replacing resorcinol\nwith an ethanol-soluble portion (ESP) from lignites rich in heteroatoms\nand alkyl side chains and employed as cathodes for Li–S batteries.\nThe results show that the specific surface area, defect, and heteroatoms\nsignificantly increase after introducing ESP, thus promoting the adsorption\nand conversion of LiPSs. S@HCNS-30 exhibits the best electrochemical\nperformance with a high initial discharge specific capacity of 1253.2\nand 782.7 mAh·g<sup>–1</sup> at 0.1C and 2C, respectively,\nand a low decay rate of 0.075% per cycle after 500 cycles, which is\nmuch superior to S@HCNS from pure resorcinol and many other coal-\nor biomass-derived carbon materials. In addition, a high discharge\nspecific capacity of 659.9 mAh·g<sup>–1</sup> was achieved\nunder challenging conditions of a depleted electrolyte (E/S = 10 μL·mg<sup>–1</sup>) and high areal density (5.3 mg·cm<sup>–2</sup>). This work not only contributes to the high-value utilization of\nlignites but also provides a facile approach for high-performance\ncathodes for Li–S batteries.