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

Abstract

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 (similar to 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.