Enhanced polysulfide conversion through metal oxide-support interaction in MnOx/MXene

Abstract

The “redox shuttling” of polysulfides in lithium sulfur batteries is commonly addressed by using a sulfur host material which binds well with the polysulfides. The sulfur host material typically contains a metal oxide which is active for polysulfide adsorption and/or conversion, and a chemically inactive conductive support for the transport of electrons away from the active sites. Most current research is focused on the interaction between polysulfides and the composite; little is done on how such interaction may be modulated by using a conductive and chemically active support in the composite. In principle, the interface between a chemically active support and metal oxide has the potential to alter the electron distribution on the polysulfide active sites, thereby altering the latter’s ability to adsorb and transform polysulfides. In this study, MnOx/MXene composites were used as a model system using the chemical activity of MXene to invoke an interfacial interaction with manganese oxide. Sulfur cathodes compounded with the MnOx/MXene composite (MnOx/MXene/S) showed improved high-rate performance (697.8 mAh g−1 at 5C) and cycling stability (fade rate of 0.027% per cycle at 3C for 1000 cycles). The oxide-support interaction in MnOx/MXene is therefore advantageous to polysulfide reutilization in Li-S batteries.