Multiple core-shelled sulfur composite based on spherical double-layered hollow carbon and PEDOT:PSS as cathode for lithium–sulfur batteries

Nanostructured sulfur cathode with a multiple core-shelled structure, featured with the spherical double-layered hollow carbon/sulfur composite (DLHC/S) coated with a conductive layer of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS), is designed and synthesized for lithium-sulfur batteries. Transmission electron microscope images of DLHC/S single nanoparticle show that the sulfur aggregates predominantly in the interior space between the two carbon shells by using a vacuum infiltration process. The electric conductivity of DLHC/S@PEDOT:PSS increases over 5 times as comparing to DLHC/S without PEDOT:PSS coating. The composite cathode exhibits a high reversible capacity of 1089 mAh g −1  at 0.2C and superior rate capacity of 510 mAh g −1 even at 4 C, and also remarkable cycling stability with a capacity decay of 0.097% per cycle after 500 cycles at 1 C. The excellent electrochemical performances for DLHC/S@PEDOT:PSS cathode are primarily attributed to the engineering of the unique multiple core-shell structure of DLHC/S@PEDOT:PSS, which inhibits the sulfur dissolution into the electrolyte and the polysulfide shuttle effect, together with the conductivity enhancement due to PEDOT:PSS coating.