Lithium-sulfur batteries are promising next-generation energy storage devices beyond conventional lithium ion batteries.However,it suffers from rapid capacity fading and poor cyclic stability.Here we report a facile in situ sulfur deposition and chemical oxidative polymerization method for preparing acetylene black/sulfur@polypyrrole (AB/S@PPy) composite as a cathode material for lithium-sulfur batteries.It is demonstrated that PPy is covered uniformly onto the surface of the AB/S composite forming a coreshell structure.In the structure,AB in the matrix and PPy on the surface acts as a combined conductive framework to provide ions and electrons transport pathways,and to inhibit the dissolution or diffusion of polysulfide into the electrolyte.The as-designed AB/S@PPy composite exhibits excellent rate capability and cyclic stability.The initial discharge specific capacity is as high as 1179.4 mAh/g,and remains at 769.3 mAh/g after 80 cycles at 0.2 C.Even at a high rate (0.5 C),a maximum discharge capacity of 811.1 mAh/g is still achieved for the AB/S@PPy composite after activation,and the capacity retention is over 62.5％ after 200 cycles.