Lithium-sulfur (Li-S) batteries with the merits of high theoretical capacity and high energy density have gained significant attention as the next-generation energy storage devices. Unfortunately, the main pressing issues of sluggish reaction kinetics and severe shuttling of polysulfides hampered their practical application. To overcome these obstacles, various strategies adopting high-efficient electrocatalysts have been explored to enable the rapid polysulfide conversions and thereby suppressing the polysulfide shuttling. This review first summarizes the recent progress on electrocatalysts involved in hosts, interlayers, and protective layers. Then, these electrocatalysts in Li-S batteries are analyzed by listing representative works, from the viewpoints of design concepts, engineering strategies, working principles, and electrochemical performance. Finally, the remaining issues/challenges and future perspectives facing electrocatalysts are given and discussed. This review may provide new guidance for the future construction of electrocatalysts and their further utilizations in high-performance Li-S batteries.

Lithium-sulfur (Li-S) batteries, known for their high energy density, are attracting extensive research interest as a promising next-generation energy storage technology. However, their widespread use has been hampered by certain issues, including the dissolution and migration of polysulfides, along with sluggish redox kinetics. Metal sulfides present a promising solution to these obstacles regarding their high electrical conductivity, strong chemical adsorption with polysulfides, and remarkable electrocatalytic capabilities for polysulfide conversion. In this review, the recent progress on the utilization of metal sulfide for suppressing polysulfide shuttling in Li-S batteries is systematically summarized, with a special focus on sulfur hosts and functional separators. The critical roles of metal sulfides in realizing high-performing Li-S batteries have been comprehensively discussed by correlating the materials’ structure and electrochemical performances. Moreover, the remaining issues/challenges and future perspectives are highlighted. By offering a detailed understanding of the crucial roles of metal sulfides, this review dedicates to contributing valuable knowledge for the pursuit of high-efficiency Li-S batteries based on metal sulfides.

Although promising strategies have been developed to resolve the critical drawbacks of lithium-sulfur (Li-S) batteries, the intractable issues including undesirable shuttling of polysulfides and sluggish redox reaction kinetics have still been unresolved thoroughly. Herein, a cobalt single-atom (CoSA) catalyst comprising of atomic Co distributed homogeneously within nitrogen (N)-doped porous carbon (Co-NPC) nanosphere is constructed and utilized as a separator coating in Li-S batteries. The Co-NPC exposes abundant active sites participating in sulfur redox reactions, and remarkable catalytic activity boosting the rapid polysulfide conversions. As a result, Li-S batteries with Co-NPC coating layer realize significantly enhanced specific capacity (1295 mAh·g⁻¹ at 0.2 C), rate capability (753 mAh·g⁻¹ at 3.0 C), and long-life cyclic stability (601 mAh·g⁻¹ after 500 cycles at 1.0 C). Increasing the areal sulfur loading to 6.2 mg·cm⁻², an extremely high areal capacity of 7.92 mAh·cm⁻² is achieved. Further in situ X-ray diffraction, density functional theory calculations, and secondary ion mass spectrometry confirm the high catalytic capability of CoSA towards reversible polysulfide conversion. This study supplies new insights for adopting single-atom catalyst to upgrade the electrochemical performance of Li-S batteries.

The sluggish kinetics of sulfur redox reactions and the potential of polysulfide shuttling pose significant challenges to the practical application of metal–sulfur batteries (MSBs). Heterostructured materials that integrate the advantages of various components serve as ideal electrocatalysts to address these issues. This review first summarizes and analyzes the engineering strategies and the proposed working principles for heterostructures. Recent advancements in the utilizations of heterostructures in sulfur hosts, separator coating layers, and interlayers are then concluded. The material designs, preparation approaches, and the crucial roles played by heterostructures are subsequently discussed, elucidating the relationship between their structural characteristics and MSB performance. Finally, the remaining challenges are identified, and the future research directions are outlined in this promising area. This work provides invaluable insights into the development of highly efficient heterostructured electrocatalysts and the regulation of sulfur conversion processes in MSBs.

Lithium–sulfur (Li–S) batteries have gained significant success as next-generation energy sources, but the slow conversion speed of polysulfides and resultant notorious shuttle effect still limit its practical utilization. Metal nitrides (MNs) with high chemical affinity and remarkable catalytic activity have been verified as highly-efficient electrocatalysts in addressing these remaining challenges. However, there is a lack of comprehensive review that clarifying the detailed working principles of MNs in Li–S batteries. This study first summarizes the recent advances in the utilization of MNs for Li–S batteries, especially in sulfur hosts, separator coating layers, and interlayers. Typical MNs in each category were then introduced, by analyzing their material designs, catalytic effects, and modulation strategies. Important perspectives on the future developments of MN-based electrocatalysts and Li–S batteries are given, possible challenges and potential research directions are outlined. This work supplies precious insights into the use of MNs and their key roles in promoting the conversions of sulfur species.