Mo2c Nanoparticles Decorated Carbon Nanofibers Loaded with Li2s as High-Performance Lithium Sulfur Battery Cathodes

Abstract

Lithium sulfur (Li-S) batteries have broad development potential in the field of electrochemical energy storage due to their high theoretical specific capacity, low cost, and environmentally friendly. However, the notorious shuttle effect of lithium polysulfides (LiPSs) during cycling process severely limits the performance improvement of Li-S batteries. In this work, carbon nanofibers (CNFs) decorated by Mo2C nanoparticles have been successfully established through electrospin combined with carbothermal reduction method. The effect of calcination temperature and Mo2C loading amount on the catalytic activity on LiPSs, as well as the electrochemical performance have been first investigated in detail. Based on the visualized adsorption and LiPSs conversion kinetics testing, the CNFs@Mo2C composites with 34 wt% Mo2C loading (CNFs@Mo2C-34%) are confirmed to be the optimized sample. By using liquid-phase impregnation to load Li2S onto the CNFs@Mo2C-34% composites to act as cathode, the assembled cells can achieve a reversible capacity of 941 mAh g-1 and 751 mAh g-1 at the current density of 0.1 C and 1 C respectively. The reversible capacity can still maintain at 550 mAh g-1, corresponding to the capacity decay rate of 0.054% per cycle.

Keywords: Lithium sulfur batteries, Li2S cathode, Mo2C, Carbon nanofibers, Electrospin