Nitrogen doped hollow porous carbon fibers derived from polyacrylonitrile for Li-S batteries

Hollow porous carbon fibers for Li-S battery electrodes were prepared by the KOH activation of carbon prepared from hollow polyacrylonitrile fibers. The fibers had a high specific surface area of 2 491 m²·g⁻¹, a large pore volume of 1.22 cm³·g⁻¹ and an initial specific capacity of 330 mAh·g⁻¹ at a current density of 1 C. To improve their electrochemical performance, the fibers were modified by treatment with hydrazine hydrate to prepare nitrogen-doped hollow porous carbon fibers with a specific surface area of 1 690 m²·g⁻¹, a pore volume of 0.84 cm³·g⁻¹ and a high nitrogen content of 8.81 at%. Because of the increased polarity and adsorption capacity produced by the nitrogen doping, the initial specific capacity of the fibers was increased to 420 mAh·g⁻¹ at a current density of 1 C.