Ultrathin lithium chalcogenide-based nanohybrid SEI layer for suppressing lithium dendrite growth and polysulfide shuttle in Li-S batteries

To advance high-energy–density Li–S batteries, it is crucial to develop strategies that enhance the energy efficiency, power capability, and cycle stability of both lithium metal anodes (LMAs) and sulfur cathodes (SCs). This study introduces an ultra-thin (∼60 nm) lithium telluride (t-Li₂Te) layer on a conventional polypropylene (PP) separator, designed to improve the Coulombic efficiency (CE) and cycling stability of LMAs and SCs. The t-Li₂Te layer features a nanoporous structure of aggregated Li₂Te nanoparticles, with nanopores filled by solid-electrolyte interface (SEI) materials during initial lithium deposition. This t-Li₂Te-SEI nanohybrid layer significantly enhanced CE for LMA, reaching maximum capacity within four cycles with only 25 % total capacity loss, contrasting with a 210 % capacity loss over ten cycles in the bare PP-based anode without t-Li₂Te. In high cut-off capacity tests (4 mA h cm⁻²), the t-Li₂Te-based system achieved stable cycling over 350 cycles, extending cycle life tenfold compared to the bare PP-based anode. For SC applications, the t-Li₂Te-SEI nanohybrid layer attained an initial CE of 98.3 %, notably higher than that (93.1 %) of the reference system. After 100 cycles, the t-Li₂Te-based SC system retained 85 % capacity, showing a 20 % improvement over systems without the nanohybrid layer.