MOF derived prismatic-like N-doped carbon nanotube in-situ embedded with Fe3O4/Fe3C heterostructure as an anchoring and catalytic center towards polysulfide in Li-S battery

The development of efficient sulfur host to address the severe shutting effect and sluggish reaction kinetics in lithium-sulfur (Li-S) batteries remains a formidable challenge. Herein, a prismatic-like carbon embedded with highly distributed Fe3O4/Fe3C heterostructure (Fe3O4/Fe3C/PNCT) as a multifunctional sulfur host is reported. In this heterostructure, the polar Fe3O4 works as an adsorbent to anchor polysulfide on heterostructure reaction interface, PNCT with 3D network provides fast e- and Li+ transfer pathways to participate reaction and Fe3C acts as a promoter to provide high catalytic activity to enhance reaction kinetics. Through the respective advantages of Fe3O4, Fe3C and PNCT, the synergetic anchoring-diffusion-catalytic conversion performance of Fe3O4/Fe3C/ PNCT exceeds their individual benefits. Experiment and DFT all confirm that the Fe3O4/Fe3C/PNCT heterostructure can form a synergetic enhancement effect to inhibit shuttling effect and promote the polysulfide reaction kinetics. On basis of these attractive superiorities, the S/Fe3O4/Fe3C/PNCT cathode shows super high initial capacities of 1432 mAh/g at 0.1 C, and 675 mAh/g at 5 C. Especially, under high sulfur loadings of 7 mg cm-2, the high area capacities of 7.6 mAh cm-2 still can be obtained. This strategy of anchoring and promoting polysulfide conversion can provide a new technology for advanced Li-S batteries.