Yolk-Shell Structure of Polyaniline-Coated Sulfur for Lithium-Sulfur Batteries

Lithium-sulfur batteries have attracted much attention in recent years due to their high theoretical capacity of 1672 mAh g(-1) and low cost. However, a rapid capacity fade is normally observed, attributed mainly to polysulfide dissolution and volume expansion. Although many strategies have been reported to prolong the cyclability, the high cost and complex preparation processes still hinder their practical application. Here, we report the synthesis of a polyaniline-sulfur yolk-shell nanocomposite through a heating vulcanization of a polyaniline-sulfur core-shell structure. We observed that this heating treatment was much more effective than chemical leaching to prepare uniform yolk-shell structures. Compared with its sulfur-polyaniline core-shell counterparts, the yolk-shell nanostructures delivered much improved cyclability owing to the presence of internal void space inside the polymer shell to accommodate the volume expansion of sulfur during lithiation. The yolk-shell material exhibited a stable capacity of 765 mAh g(-1) at 0.2 C after 200 cycles, representing a promising future for industrial scale Li-S batteries.