Defect engineered MoWS alloy catalyst boost the polysulfide conversion in lithium–sulfur battery

Abstract Despite of high theoretical energy density, the practical application of Li–S battery (LSB) is limited by its intrinsic hurdles such as lithium polysulfides (LiPSs) shuttling effect and limited sulfur loading and its utilization in cathode. Here, we develop a defect engineered MoxW1-xS2-y alloy catalyst (D-MoWS) deposited on carbon nanofiber (CNF) via a facile hydrothermal synthesis followed by a thermal-solvent vapor etching method to expedite the LiPSs redox kinetics and resolve the limit of sulfur utilization in LSB. The LSB cells assembled using the D-MoWS–CNF–S cathode show the highest specific capacity of 1586 mAh g−1 and excellent areal capacity up to 13.5 mAh cm−2 at high areal sulfur loading of 10 mg cm−2, resulting in the highest energy density of 1090 Wh kg−1 (w.r.t total weight of anode and cathode). Our mechanistic study and ex-situ SEM analysis prove that D-MoWS catalyst accelerates the LiPSs conversion, prevents the shuttling effect and Li-metal corrosion, therefore, effectively reduces the negative/positive electrode capacity (N/P) ratio to the lowest reported value of 1.7.