Embedding Fe₃C and Fe₃N on a Nitrogen-Doped Carbon Nanotube as a Catalytic and Anchoring Center for a High-Areal-Capacity Li–S Battery

The biggest obstacles of putting lithium–sulfur batteries into practice are the sluggish redox kinetics of polysulfides and serious “shuttle effect” under high sulfur mass loading and lean-electrolyte conditions. Herein, Fe3C/Fe3N@nitrogen-doped carbon nanotubes (NCNTs) as multifunctional sulfur hosts are designed to realize high-areal-capacity Li–S batteries. The Fe3N and Fe3C particles attached to NCNT can promote the conversion of polysulfides. Besides, NCNT can not only enhance the chemisorption of polysulfides but also increase the special surface area and electrical conductivity by constructing a three-dimensional skeleton network. Integrating the merits of high electrical conductivity, high catalytic activity, and strong chemical binding interaction with lithium polysulfides (LiPSs) to achieve in situ anchoring conversion, the Fe3C/Fe3N@NCNT multifunctional hosts realize high sulfur mass loading and accelerate redox kinetics. The novel Fe3C/Fe3N@NCNT/S composite cathode exhibits steady cycle ability and a high areal capacity of 9.10 mAh cm–2 with a sulfur loading of 13.12 mg cm–2 at 2.20 mA cm–2 after 50 cycles.