Enhanced electrochemical performance of sulfur/carbon nanocomposite material prepared via chemical deposition with a vacuum soaking step

A sulfur/carbon nanocomposite was prepared by a simple chemical deposition method. A feasible vacuum soaking step was introduced to absorb the sulfur source (Na2Sx) into the carbon micropores/mesopores. It is confirmed from the scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), galvanostatic discharge-charge, cyclic voltammetry (CV) and electrochemical impedance spectra (EIS) that the S/C composite with vacuum soaking (78 wt% sulfur) leads to more dispersion of sulfur into the carbon micropores/mesopores and displays better electrochemical features, compared to the S/C composite without vacuum soaking, the synthesized sulfur/carbon and pristine sulfur/carbon ball-milled composites. The S/C cathode with vacuum soaking delivers an initial discharge capacity of 1116.1 mAh g−1 (based on sulfur weight) and retains 534.2 mAh g−1 after 150 cycles with a discharge/charge rate of 0.35 C. The stable capacity retention and sturdy structure of the electrode are attributed to an intimate nanoscale contact established between the smaller sized sulfur and the conductive carbon.