Electrochemical performance of corncob-like porous carbon rods as cathode materials of a lithium-sulfur battery

Abstract

This study demonstrates an electrospinning method using sodium carbonate as a pore-forming agent to construct three-dimensional (3-D) porous carbon fibers (PCFs). Such corncob-like porous and channel structures exhibit unique physicochemical properties, and a high density of pores improves the surface roughness of the materials, so that the materials have a very high sulfur-carrying capacity. Confinement effects provided by porous containers and dispersed channels not only buffer volumetric expansion of sulfur during cycles, but also facilitate electrolyte transport to some extent and increase the rate of utilization of active substances. Furthermore, S-C bonds can enhance chemical adsorption of carbon for sulfur and improve the structural stability of the materials. The results indicate that PCFs, as sulfur carriers, provide a good electrochemical performance. The specific discharge capacity of sulfur-carrying FCFs (PCF/S) at a high current density of 1.1 C is still higher than that of the sulfur-carrying carbon fibers (CF/S) at a lower current density of 1.0 C. After 300 cycles, the specific capacity of the PCF/Sat 1.1 C remains at 660 mAh g−1while that of CF/S at 1.0 C is only 246 mAh g−1.