A novel sulfur/carbon hollow microsphere yolk−shell composite as a high-performance cathode for lithium sulfur batteries

Abstract

A hollow carbon microsphere (HC) material was synthesized by hydrothermal method, which could be used as a potential hard template. Active sulfur is encapsulated into the hollow carbon microspheres via simple impregnation and heat treatments to design a sulfur−hollow carbon microsphere (S−HC) composite with the novel yolk−shell structure. The hollow carbon shell, acts as a conductor to provide a highly conductivity and short Li⁺ diffusion distance, as well as absorbs polysulfides to improve the cycle ability of the S−HC composite in lithium sulfur (Li−S) batteries. The internal void space inside the shell can accommodate the volumetric expansion of sulfur during lithiation. The initial discharge capacity of S−HC cathode is as high as 1420 mA h g⁻¹ at 0.1 C. After a 100 cycle stability test, the S−HC cathode exhibits still as high as 710 mA h g⁻¹ at 0.2 C. Test results indicate that the S−HC composite is a promising host material for the sulfur cathode in the Li−S battery applications.