Functional separator with VGCF/PPY coating for high cyclic stability lithium-sulfur battery

Repeated dissolution and deposition of polysulfide during the cycle could lead to a non-conductive polysulfide layer on the cathode electrode, which would cause the decrease of conductivity for the positive electrode and limit the effect of the sulfur-based conductive material. Therefore, we proposed a vapor growth carbon fiber/polypyrrole (VGCF/PPY) dual functional separator, which can increase the conductivity by VGCF and absorb polysulfide by PPY. Finally, the VGCF/PPY functional separator displays an initial discharge specific capacity of 1085 mAh g−1 at 0.1 C. The capacity remains at 768 mAh g−1 after 200 cycles with a capacity decay of 0.146% per cycle, showing excellent cycle stability.