Nitrogen/sulfur co-doped ordered carbon nanoarrays for superior sulfur hosts in lithium-sulfur batteries

A universal and low-cost biomass waste, soybean residue, that was derived from a soybean product processing plant, was used to fabricate nitrogen/sulfur co-doped, ordered carbon nanoarrays (NS-OCNA/S). The effects of nitrogen and sulfur co-doping and the addition of formaldehyde on the structure and properties of these novel materials were investigated using X-ray diffraction (XRD), Raman spectrometry, scanning electron microscopy (SEM) techniques and galvanostatic charge/discharge tests. With high levels of sulfur doping, the nitrogen/sulfur co-doped ordered carbon nanoarrays (NS-OCNA/S) were found to possess hierarchical pores and a high pore volume. The NS-OCNA/S exhibited good electrical conductivity, excellent discharge capacity and cycling performance. When the NS-OCNA/S was used in Li-S batteries it was found that the charge capacity of the cell decayed from 914 to 739 mAh g^-1, with a capacity retention 81% over 600 cycles at 2 C. This successful research effort has identified new, high-performance materials derived from bio-resources for use in Li-S batteries.