A Review of Heteroatom Doped Materials for Advanced Lithium-Sulfur Batteries

High theoretical capacity and high energy density make lithium sulfur (Li-S) batteries a competitive candidate for next-generation energy storage systems. However, achieving the practical application of Li-S batteries is still a huge challenge due to some inevitable obstacles. Poor conductivity of active sulfur, large volume expansion of cathode, and severe shuttle effect of lithium polysulfides (LiPSs) greatly limit the capacity of cells and lead to unsatisfied cycle performance. Therefore, various sulfur host materials have been proposed and investigated, which should possess good conductivity, porous structure, and strong immobilization capability for LiPSs. Unfortunately, it is incompetent to cover all the advantages mentioned above for pristine materials. Heteroatom doping fundamentally manipulates the electronic structure and polarity of materials, leading to some unprecedented properties, and subsequent enhancement in electrochemical performance. This review systematically summarizes the recent progress of heteroatom (metal single atom and non-metal atom) doping in various materials including carbon materials, graphitic carbon nitride (g-C3N4), and metal compounds as the ideal sulfur host. Furthermore, the relationship between the unique features of sulfur host materials originated from heteroatom doping and enhanced performance of cells is comprehensively discussed.