Rational design of MOFs-derived Fe3O4@C interwoven with carbon nanotubes as sulfur host for advanced lithium‑sulfur batteries

Abstract

Abstract The practical implementation of lithium‑sulfur (Li S) batteries has been hindered by limited power density and slow electrochemical reaction kinetics resulted from the shuttle effect of soluble polysulfides. Conventional carbonaceous materials are difficult to effectively adsorb polysulfides, and polar metal oxides are expected to adsorb polysulfides through strong interactions and promote electrochemical conversion. In this work, carbon nanotubes/MIL-88B microspheres were obtained by simple spray-drying, subsequently, carbon nanotubes/Fe3O4@C (CNT/Fe3O4@C) composites were obtained by high-temperature calcination, and Fe3O4@C nanorods was derived from MIL-88B. The interwoven CNT network forms a three-dimensional conductive path, which ensures that the sulfur cathode has excellent conductivity. The polar Fe3O4 nanoparticles are covered by carbon layer, which not only adsorb polysulfides through strong interaction, but also serve as a catalyst to improve the kinetics of chemical reactions. Benefiting from these characteristics, the CNT/Fe3O4@C composite is considered to be an excellent sulfur host, Li S batteries exhibit superior cyclability performance (with 0.062% decay per cycle at 1.5C), exceptional rate performance (674 mAh g−1 at 3C), and high area capacity (4.1 mAh cm−2 at 0.2C).