Infiltrating sulfur into a highly porous carbon sphere as cathode material for lithium–sulfur batteries

•A highly porous carbon (HPC) with regular spherical morphology was synthesized.•Sulfur/HPC composites were prepared by melt–diffusion method.•Sulfur/HPC composites showed improved cyclablity and long-term cycle life.

Sulfur composite material with a highly porous carbon sphere as the conducting container was prepared. The highly porous carbon sphere was easily synthesized with resorcinol–formaldehyde precursor as the carbon source. The morphology of the carbon was observed with field emission scanning electron microscope and transmission electron microscope, which showed a well-defined spherical shape. Brunauer–Emmett–Teller analysis indicated that it possesses a high specific surface area of 1563 m2 g−1 and a total pore volume of 2.66 cm3 g−1 with a bimodal pore size distribution, which allow high sulfur loading and easy transportation of lithium ions. Sulfur carbon composites with varied sulfur contents were prepared by melt–diffusion method and lithium sulfur cells with the sulfur composites showed improved cyclablity and long-term cycle life.

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