Highly dispersed sulfur in multi-walled carbon nanotubes for lithium/sulfur battery

A facile method is developed for homogeneous dispersion of sulfur (S) nanoparticles in multi-walled carbon nanotubes (MWCNTs). The process involves the modification of MWCNTs via oxidation catalyzed by acid and the introduction of sulfur nanoparticles into the MWCNTs through direct precipitation. The resulting sample (precipitated S/MWCNTs) is characterized with scanning electron microscopy and thermogravimetric analysis, and its performance as cathode of lithium/sulfur battery is investigated with a comparison of the sample prepared by ball-milling (ball-milling S/MWCNTs). It is found that the precipitated S/MWCNTs exhibit better battery performance than the ball-milling S/MWCNTs. The initial discharge capacity is 1,299 mA h g(-1) for the precipitated S/MWCNTs but only 839 mA h g(-1) for ball-milling S/MWCNTs at 0.02 C. The capacity remains 800 mA h g(-1) for the precipitated S/MWCNTs but only 620 mA h g(-1) for ball-milling S/MWCNTs at 0.05 C after 50 cycles. The better performance of the precipitated S/MWCNTs results from the improved uniformity of S dispersed in MWCNTs through precipitation.