Ultrathin Conductive Interlayer with High-Density Antisite Defects for Advanced Lithium–Sulfur Batteries

Lithium–sulfur (Li–S) batteries are promising next-generation rechargeable batteries due to thier high energy density, low cost, and environmental friendliness. However, the extremely low electrical conductivity of sulfur and the dissolution of polysulfides limit their actual electrochemical performances, especially in the case of high sulfur mass loading. Here, a new strategy based on intrinsic point defects of materials is proposed to simultaneously enhance the electrical conductivity of active material and regulate the migration of polysulfides. Taking advantage of ultrathin and lightweight Bi₂Te_2.7Se_0.3 (BTS) interlayers with high-density antisite defects on the separator surface, the Li–S battery with BTS interlayer shows a capacity of 756 mAh g⁻¹ at 2C and a low capacity decay rate of 0.1% over 300 cycles. The BTS interlayer can not only enhance the active material utilization but also improve capacity retention. The defect engineering strategy accompanied with facile method is promising for the development of advanced Li–S batteries for practical application.