Journal Article

Two-Step Synthesis of Sulfur/Graphene Composite Cathode for Reehargeable Lithium Sulfur Batteries

LI Jingyin LI Na LI Chaagjia GUO Yufeng

2015

Overview

Sulfur/graphene composites with different sulfur contents were prepared by two-step synthesis, where graphene was regarded as a carrier of sulfur active substance. The surface structure and crystal form of the composites obtained were characterized and compared by X-ray diffraction （XRD）, scanning electron microscopy （SEM）, and transmission electron microscopy （TEM）. It was found that sulfur was partially coated by graphene. The graphene folds provided more nano-pores and electron transport channels for sulfur. From TGA results, the sulfur contents of the sulfur/graphene compositcs measured were about 42.32 wt%, 54.94 wt%, and 65.23 wt%. Electrochemical tests demonstrated that sulfur/graphene composite （x=54.94 wt%） cathode exhibited better capacity retention （40.13%） compared with the pure cathode （20.46%）, where an initial discharge capacity was up to 1 500 mAh.g-t and it remained about 600 mAh·g-1 after 30 cycles. Furthermore, the electrochemical reaction mechanism and the state of reaction interface for Li/S battery were analyzed by cyclic voltammogram and AC-impedance spectra. The results indicated that the sulfur/graphene composite with a sulfur content of 54.94 wt%, based on a two-step synthesis, contributed to improving electrochemical properties of lithium/sulfur battery

• Subject: 两步合成 / 扫描电子显微镜 / 正极 / 电化学反应机理 / 电池 / 石墨复合材料 / 硫磺 / 透射电子显微镜