Hierarchical porous carbon modified with ionic surfactants as efficient sulfur hosts for the high-performance lithium-sulfur batteries.

Based on first-principles calculations, the hierarchical porous carbon/sulfur composites decorated by ionic surfactants (SDBS, SDS, CTAB) are firstly reported as the cathode materials for advanced lithium-sulfur batteries. The morphology, structure and electrochemical properties of the as-synthesized hierarchical porous carbon/sulfur composites are characterized by transmission electron microscopy (TEM), field-emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), nitrogen adsorption/desorption isotherm, Raman spectra, thermogravimetric analyses (TGA) and electrochemical tests. First-principles calculations reveal that lithium polysulfides (LiS and Li 2 S) can bind strongly to the O or N functional groups in the surfactants. Additionally, the hierarchical porous carbon, which derived from a very cheap and abundant cellulose bio-waste lotus seedpod shells, possesses a large specific surface area (2923.04 m 2 /g) and a high pore volume (1.4823 cm 3 /g). Hence, an outstanding initial capacity of 1138 mAh/g at a high discharge rate of 0.5 C with large areal mass loading of 3.2 mg/cm 2 and high sulfur contents of 86.55 wt% is obtained. Even after 100 cycles, the cathode material still represents an excellent cycling stability with reversible capacity of 1116 mAh/g at 0.1 C, low capacity decay of 0.16% per cycle and high coulombic efficiency of about 97%. [ABSTRACT FROM AUTHOR]