context: In this review, we have provided a comprehensive overview of the design, synthesis, and application of metal sulfides in rechargeable Li–S batteries. We aimed to summarize important concepts to boost the practical development of high-energy-density Li–S batteries. As a promising polar substrate, metal sulfides have considerable benefits, including a moderately strong affinity for active sulfide binding, high electronic conductivity, the ability to modulate redox reaction kinetics, and a high activity capacity contribution. Through the use of metal sulfides, great progress has been made in improving sulfur cathodes, design of interlayers, modification of separators, and protection of lithium anodes. Despite these achievements, challenges remain in terms of developing affordable large-scale synthesis techniques, elucidating an in-depth mechanism of binding LiPSs, enhancing the rationality and reliability of theoretical simulations, and building stable high-energy-density Li–S batteries over routine LIBs. We hope that this review will inspire greater interest in the use of metal sulfides and other related materials with similar effects as polar substrates for the exploitation of advanced Li–S batteries.
answer: lithium 