Sulfur grown around carbon nanotubes as a cathode material for Li/S battery

Sulfur/multi-walled carbon nanotubes (MWCNTs) composites have been successfully prepared by an in situ growth strategy as a cathode material for lithium/sulfur battery. The microstructure and morphology of the sulfur/MWCNTs composites are characterized by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). From the results, it is found that the nano-sulfur (shell) grows around the MWCNTs (core) and is well-dispersed over the whole surface of the MWCNTs. Tested by coin type cells, the composite materials exhibited the sulfur utilization approaching to 78% for the first cycle, the capacity retention closing to 84% after 100 cycles at various rates. The excellent electrochemical performance could be attributed to the nano-size sulfur and the homogeneous distribution of sulfur on MWCNTs matrix, resulting from this novel in situ growth method, which not only enhances the reactive activity of sulfur during charge-discharge processes but also provides stable electrical and ionic transfer channels.