Sulfur encapsulated in porous carbon nanospheres and coated with conductive polyaniline as cathode of lithium–sulfur battery

We report a novel composite, sulfur (S) encapsulated in porous carbon nanospheres (PCNS) and coated with conductive polyaniline (PANI) (PCNS-S@PANI), as cathode of lithium–sulfur battery. PCNS is prepared by convenient and controllable hydrothermal synthetic route and loaded with S via chemical deposition and then coated with conductive polyaniline via in situ polymerization under the control of ascorbic acid. The physical and electrochemical performances of the resulting PCNS-S@PANI are investigated by scanning electron microscopy, X-ray powder diffraction, X-ray photoelectron spectroscopy, nitrogen adsorption–desorption isotherms, thermogravimetric analysis, electronic conductivity measurement, galvanostatic charge–discharge test, and electrochemical impedance spectroscopy. It is found that PCNS-S@PANI exhibits excellent charge–discharge performances as cathode of lithium–sulfur battery: delivering a discharge capacity of 881 mAh g⁻¹ at 0.2 C (1 C = 1672 mA g⁻¹) with a capacity retention of 72 % after 100 cycles and a rate capacity of 324 mAh g⁻¹ at 2 C. These natures can be attributed to the co-contribution of PCNS and conductive PANI to the improvement in electronic conductivity and chemical stability of sulfur cathode.