MOFs-Derived Porous Mo2C-C Nano-Octahedrons Enable High-Performance Lithium-Sulfur Batteries

Abstract The shuttle effect causing by the dissolution of lithium polysulfides (LiPSs) and sluggish redox reaction kinetics during the charge/discharge processes significantly reduce the cycle life and sulfur utilization in lithium-sulfur (Li-S) batteries. Herein, Mo2C-C nano-octahedrons (Mo2C-C NOs) with Mo2C nanoparticles embedded in a three-dimensional porous carbon matrix have been prepared via a metal-organic frameworks (MOFs) assisted strategy, and used as the sulfur host for Li-S batteries. The Mo2C-C NOs@S cathode demonstrates a high initial specific capacity of 1396 and 1050 mAh g-1 at 0.1 C and 1 C, respectively, with an ultra-low average specific capacity decay rate of 0.0457% per cycle within 600 cycles at 1 C. Moreover, Mo2C-C NOs@S cathode with high areal sulfur loading of 4.2 mgS cm-2 can deliver a high initial discharge specific capacity of 807 mAh g-1, and a capacity of 623 mAh g-1 after 100 cycles at 0.5 C. The existence of Mo2C nanoparticles can not only immobilize LiPSs via the formation of Mo-S bond, but also electrocatalytically accelerate the redox kinetics towards LiPSs conversion. Meanwhile, the interconnected porous carbon matrices contributes to effective sulfur/electrolyte infiltration, fast electron/Li+ ion transportation and sufficient buffer for volume change.