Boosting the anchoring and catalytic capability of MoS2 for high-loading lithium sulfur batteries

Abstract

A high sulfur loading and low electrolyte/sulfur ratio are considered prerequisites for practical high-energy lithium sulfur batteries (LSBs); however, shuttling and the sluggish conversion of flooded polysulfides make it challenging to achieve the full utilization of active materials with an extended cyclic life. Herein, we explore 1T MoS₂ nanodots as powerful electrocatalyst to overcome this issue. Electrochemical and synchrotron in situ X-ray diffraction characterizations revealed that 1T MoS₂ nanodots with numerous active sites are favored to trap and propel the redox reactions for polysulfides. First-principle calculations indicated that the surface and Mo-terminated edges of 1T MoS₂ provide stronger anchor sites for Li₂S, a lower Li–S decomposition barrier, and faster Li ion migration than those for the 2H phase, which suggest the unique catalytic property for edge-rich 1T MoS₂ nanodots in LSBs. In the presence of a small amount of 1T MoS₂ nanodots, porous carbon/Li₂S₆ cathodes exhibited remarkable electrochemical performance retaining a capacity of 9.3 mA h cm⁻² over 300 cycles under high sulfur loading of 12.9 mg cm⁻² and a low electrolyte/sulfur ratio of 4.6 μL mg⁻¹, which rivals the performance of the state-of-the-art LSBs. Our combined experimental and theoretical analyses rationalized the use of nanodot catalysts in high energy rechargeable batteries.