One-pot approach to synthesize PPy@S core-shell nanocomposite cathode for Li/S batteries

A polypyrrole-coated sulfur composite (PPy@S) was synthesized by in situ polymerization of pyrrole monomers on the surface of nano-sulfur particles. High resolution transmission electron microscopy and energy dispersive spectroscopy mapping showed the formation of a highly developed core-shell structure with uniform PPy coating on the surface of sulfur particles. The electrochemical properties of the resulting PPy@S composite cathode have been evaluated by cyclic voltammograms and galvanostatic discharge-charge cycling. The results show that the PPy@S composite exhibits a reversible capacity of 1,200 mAh g ^-1 at the initial cycle, with 913 mAh g^-1 remaining after 50 cycles. Even up to 2.5 C, a reversible capacity of 437 mAh g^-1 is obtained. The excellent electrochemical performance can be attributed to the conductive PPy-coating nanolayer, which provides both an effective electron conduction path and a strong physical and chemical confinement setting for elemental sulfur and resident polysulfides, minimizing the loss of active material during cycling.