A double-shelled structure confining sulfur for lithium-sulfur batteries

Lithium-sulfur battery has attracted notable attention because of its high special capacity (1675 mAh g−1). However, polysulfide dissolution and low electronic conductivity of sulfur cathode usually cause significant capacity fading during cycling. In this paper, we introduce a double-shelled structure of reduced graphene oxide@polyaniline@sulfur (rGO@PANI@S) composite, which not only can prevent volume expansion at sulfur charge/discharge process, inhibit lithium polysulfides dissolution and shuttle in the electrolyte, and also ensure a good electro-conductibility for sulfur cathode materials. The microstructure and electrochemical performance of the rGO@PANI@S cathode are investigated systematically. The results show that polyaniline inner shell with thickness of about 27.5 nm is coated uniformly on the surface of S submicron particles and few-layered reduced graphene oxide sheets are chemically bonded at the outer surface with a high sulfur content (74 wt%). When used as cathode for lithium-sulfur battery, the rGO@PANI@S composite shows an initial capacity of 1482.7 mAh g−1 at a rate of 100 mA g−1 and retains reversible capacity of 812.1 mAh g−1 over 100 cycles. This all-solution-based process is scalable and the double-shell wrapping structure has promising candidate in designing rechargeable sulfur cathode for application. [Display omitted] •A double-shell structured S@PANI@rGO is prepared by a two-step liquid-phase method.•Inner PANI nano-coating is applied as a conducting container for housing sulfur.•Outer rGO layer can further buffer the volumetric expansion of sulfur cathode.•The double-shell provides functional surface to chemically confine polysulfides.•The S@PANI@rGO composite exhibits improved cycle performance and rate capability.