Freestanding Mo2C-decorating N-doped carbon nanofibers as 3D current collector for ultra-stable Li-S batteries

The shuttle effect in Li-S batteries caused by high solubility of lithium polysulfides (LiPSs) results in rapid capacity decay and low Coulombic efficiency. To address these issues, we propose a strategy to suppress the shuttle effect by constructing freestanding N-doped carbon nanofibers with well-distributed conductive Mo2C nanoparticles (Mo2C-NCNFs) as 3D current collectors for Li-S batteries. DFT calculations demonstrate that the Mo2C possesses strong and stable adsorption affinity to LiPSs, thus effectively alleviating the shuttle effect. The 3D interconnected nanofibers possess the advantages of high electronic conductivity, structural integrity, fast electrochemical reaction kinetics, and very few dead volumes from inactive additives. As a result, a promising electrochemical performance with a good combination of high specific capacity of 1086 mAh g−1 at 0.2 C, extremely stable cycling performance of over 250 cycles without obvious capacity fading. This strategy is enlightening in designing high performance electrodes for Li-S batteries.