Incorporation of Mo2C nanoparticles to pollen-derived 3D porous carbon as electrocatalyst for high performance lithium-sulfur batteries

The practical application and development of lithium-sulfur (Li-S) batteries are limited by the slow redox reaction kinetics and shuttle effect of polysulfide lithium (LiPSs). To address these issues, three-dimensional porous carbon (PC, derived from rapeseed pollen) modified with molybdenum carbide (Mo2C) nanoparticles is prepared by a simple and environment-friendly method. On the one hand, the PC-Mo2C host material can facilitate the uniform loading of sulfur and reduce its volume expansion due to its porous carbon structure. On the other hand, it mitigates the shuttle effect by effective chemical adsorption of LiPSs to form strong physical confinement and catalyze the conversion of LiPSs via the aid of the decorated Mo2C nanoparticles. Density functional theoretical calculations also illustrate the Mo2C nanoparticles are capable of inhibiting the shuttle of LiPSs and further improving the cycling stability. The results show that the PC-Mo2C/S electrode exhibits excellent electrochemical performance with high cycle stability (fading rate of 0.066 % per cycle at 0.2C and 0.054 % per cycle at 1C) and outstanding rate capacity (623.2 mAh g- 1 at 5C).