Pyrolyzed porous spherical composites of polyacrylonitrile-Ketjenblack carbon and sulfur (pPAN-KB/S) with a high sulfur content (ca. 72%) and enhanced conductivity and porosity (pore volume: 1.42 cm3/g; BET surface area: 727 m2/g) were prepared by an aerosol-assisted process and applied as cathode for lithium-sulfur batteries. Electrochemical tests showed that the pPAN-KB/S composite exhibited a high capacity of 866 mAh/g (based on sulfur) after 100 cycles at 0.5C (1C = 1.68 A/g) and a good rate performance at high current density (431 mAh/g at 5C). In addition, a pPAN-KB/S composite electrode with high sulfur loading (ca. 4.4 mg-S/cm2) exhibited impressive electrochemical performance with a reversible capacity of 513 mAh/g and 576 mAh/cm3 (based on sulfur) and a coulombic efficiency >99% after 100 cycles at 0.5C.