Highly Conductive Quasi‐1D Hexagonal Chalcogenide Perovskite Sr8Ti7S21 with Efficient Polysulfide Regulation in Lithium‐Sulfur Batteries

Abstract Lithium‐sulfur batteries (LSBs) are regarded as one of the most promising candidates for next‐generation energy storage systems. However, the commercialization of LSBs is still hindered by several technical issues, including the notorious polysulfide migration from the cathode to the anode and the sluggish sulfur conversion kinetics. Herein, a quasi‐1D hexagonal chalcogenide perovskite, Sr 8 Ti 7 S 21 , is demonstrated as an efficient sulfur host able to overcome these limitations. Experimental results and density functional theory calculations show Sr 8 Ti 7 S 21 to offer strong lithium polysulfides (LiPS) binding through multiple bond formation. Besides, Sr 8 Ti 7 S 21 effectively facilitates the kinetics of the LiPS redox reaction. As a result, S@Sr 8 Ti 7 S 21 ‐based cathodes exhibit excellent initial capacities up to 1315 mAh g −1 at 0.2C, impressive cycling stability with an average capacity decay rate of 0.08% per cycle over 400 cycles at 1C, and a high areal capacity of 6.58 mAh cm −2 under a high sulfur loading of 6.5 mg cm −2 . This work reveals the potential capabilities and promising prospects of chalcogenide perovskites in advancing LSBs technology.