In order to explore the potential application of sulfur in aqueous rechargeable batteries, core-shell sulfur-polypyrrole (S@PPy) composites were prepared through a novel one-pot and surfactant-free method. Sulfur exhibits a very high capacity of 473 mA h g(-1) and good cycling stability in an aqueous Li(2)SO(4) electrolyte due to the polypyrrole coating.