Rational design of sulfur-containing composites for high-performance lithium-sulfur batteries

Sulfur has received considerable attention as a cathode material for lithium-sulfur (Li-S) batteries due to its high theoretical energy density (2567 W h kg(-1)), high earth abundance, and environmental benignity. However, the insulating nature of sulfur and the shuttle effect of soluble lithium polysulfides result in serious technical issues, such as low utilization rate of sulfur, reduced columbic efficiency, and poor cycling stability, which compromise the high theoretical performance of Li-S batteries. In the past years, various attempts have been made to achieve high specific capacity and reliable cycling stability of Li-S batteries. Incorporation of sulfur into functional host materials has been demonstrated to be effective to improve the electrochemical performance of sulfur-based cathodes via enhancing the electron and Li ion conductivities, immobilizing sulfur/lithium polysulfides in cathodes, and accommodating the volume changes in sulfur-based cathodes. Therefore, the rational design of sulfur-containing composites needs to be emphasized as key strategies to develop high-performance cathodes for Li-S batteries. In this perspective, after reviewing the achievements obtained in the design of sulfur-containing composites as cathodes for Li-S batteries, we propose the new issues that should be overcome to facilitate the practical application of Li-S batteries.