High performance lithium-sulfur batteries using threedimensional hierarchical porous carbons to host the sulfur

Abstract

Lithium-sulfur batteries are promising for future energy storage because of their high-energy density and low price. However, they have many problems, especially the large volume change during cycling and the shuttle effect of the soluble polysulfides. To solve these problems, a three-dimensional hierarchical porous carbon (3D-HPC) was investigated as the sulfur host of a lithium-sulfur battery. The 3D-HPC was prepared by a template method using polymethyl methacrylate and zinc oxide as the templates to form mesopores and macropores, respectively. The results showed that the interconnected macroporous channels and abundant large mesopores formed a three-dimensional conductive carbon network which is beneficial for electron/ion transfer and relieves the cathode volume change by the physical limiting effect. The pores alleviate the shuttle effect by the capillary condensation. A 3D-HPC-S composite used as the cathode has excellent electrochemical properties. The first discharge specific capacity of the 3D-HPC-S is 1314.6 mAh g−1 at 0.2 C with a sulfur loading of 70%. After 100 cycles, the capacity retention rate is 69.13%. At 0.5 C, the capacity retention rate after 200 cycles is 59.02% and the average coulombic efficiency is 98.16%.