Synthesis and Electrochemical Performance of Sulfur/Highly Porous Carbon Composites

摘要

Sulfur/highly porous carbon (HPC) composites were synthesized by thermally treating a mixture of sublimed sulfur and HPC. The microstructure of the HPC and the composite was characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), and Brunauer—Emmett—Teller (BET) surface area. The specific surface area of HPC reaches up to 1472.9 m~2/g, which is sharply reduced to 24.4 m~2/g in the sulfur/HPC composite with 57 wt % sulfur. The electrochemical performance of the composites as cathode materials in organic electrolytes was studied by the galvanostatic method and cyclic voltammetry. The sulfur/HPC composite with 57 wt % sulfur delivers the initial high specific capacity up to 1155 mAh/g and a stable capacity of 745 mAh/g after 84 cycles at the current density of 40 mA/g. In addition, it is demonstrated that the excellent cycling stability of the sulfur/HPC composite can be obtained at different current densities. On the basis of the analysis of the microstructure and electrochemical performance, it is confirmed that HPC can effectively prevent the shuttle behavior of the lithium/sulfur battery.