Mo2 C/C Hierarchical Double-Shelled Hollow Spheres as Sulfur Host for Advanced Li-S Batteries.

Abstract

One of the major challenges regarding the sulfur cathode of Li-S batteries is to achieve high sulfur loading, fast Li ions transfer, and the suppression of lithium polysulfides (LiPSs) shuttling. This issue can be solved by the development of molybdenum carbide decorated N-doped carbon hierarchical double-shelled hollow spheres (Mo2 C/C HDS-HSs). The mesoporous thick inner shell and the central void of the HDS-HSs achieve high sulfur loading, facilitate the ion/electrolyte penetration, and accelerate charge transfer. The microporous thin outer shell suppresses LiPSs shuttling and reduces the charge/mass diffusion distance. The double-shelled hollow structure accommodates the volume expansion during lithiation. Furthermore, Mo2 C/C composition renders the HDS-HSs cathode with improved conductivity, enhanced affinity to LiPSs, and accelerated kinetics of LiPSs conversion. The structural and compositional advantages render the Mo2 C/C/S HDS-HSs electrode with high specific capacity, excellent rate capability, and ultra-long cycling stability in the composed Li-S batteries.