Synthesis of carbon coated Fe₃O₄ grown on graphene as effective sulfur-host materials for advanced lithium/sulfur battery

Lithium/sulfur battery (LSB) is considered as one of the most promising battery systems due to its high energy density of 2600 Wh kg⁻¹. Nevertheless, the LSB suffers from some inherent problems that impede its practical application. To circumvent these problems, we grow carbon-coated ferroferric oxide (Fe₃O₄) nanoparticles on graphene (Fe₃O₄@C-G) as an effective sulfur host for LSB via a facile hydrothermal method followed by calcination. Highly conductive graphene is utilized to homogeneously deposit the carbon-coated Fe₃O₄ nanoparticles (Fe₃O₄@C), which enable rapid and steady long-distance electron transport. Moreover, the carbon coated particles of Fe₃O₄@C exhibit a developed micro-mesoporous structure, which not only provide space for sulfur loading to prepare a composite Sulfur/carbon-coated Fe₃O₄ nanoparticles on graphene (S/Fe₃O₄@C-G) cathode, but also provide channels for the interaction between Fe₃O₄ and lithium polysulfides. Furthermore, a strong chemical affinity of Fe₃O₄ nanoparticles coated by micro-mesoporous carbon layers towards polysulfides can be strengthened through the polar-polar interaction. Owning these advantages, the S/Fe₃O₄@C-G composite cathode deliver a high initial capacity of 1425 mAh g⁻¹ at 0.2 C and maintain a capacity of 1102 mAh g⁻¹ after 100 cycles.