Electrocatalytic conversion of lithium polysulfides by highly dispersed ultrafine Mo2C nanoparticles on hollow N-doped carbon flowers for Li-S batteries

The significant challenge in exploring novel nanostructured sulfur host materials for Li-S batteries is to simultaneously mitigate the notorious shuttle effect and catalytically enhance the redox kinetics of lithium polysulfides (LPSs). Herein, a novel ultrafine Mo2C nanoparticles uniformly distributed on 2D nanosheet-assembled 3D hollow nitrogen-doped carbon flowers (HNCFs) is designed. The Mo2C/HNCFs architecture with unique flower-like morphologies not only efficiently suppressed the aggregation of 2D nanosheets but also highly distributed the ultrafine Mo2C nanoparticles that act as catalytic active sites for efficient adsorption and conversion of LPSs. Furthermore, the 3D hierarchical arrangement can afford ample internal space to accommodate sulfur species, large volume expansion, 3D electron pathway, and physical/chemical blockage of LPSs to reduce the loss of active materials. The Mo2C/HNCFs composite exhibits a high rate capability, unprecedented capacity retention of 92% over 100cycles at 0.5C placing Mo2C/HNCFs one of the best LPSs adsorbents and electrocatalysts.