Hierarchical MoxC@NC hollow microsphere with incorporated Mo vacancies as multifunctional confined reactors for high-loading Li-S batteries

The undesirable shuttling of lithium polysulfides (LiPSs) and sluggish redox kinetics lead to the serious reduction in cycle life and sulfur utilization. Herein, to tackle these problems simultaneously, a strategy is demonstrated for preparing defective MoxC@NC with rich incorporated Mo vacancies, additional active sites and nitrogen-doped carbon (NC) coating for boosting the performance of Li-S batteries. The hollow structure of MoxC@NC achieves the physical confinement of the active materials and facilitates the ion/electrolyte penetration. Relevant experiments confirmed that the meso-microporous thin outer shell and the uniformly distributed MoxC nanoparticles in the shell can significantly suppress the LiPSs shuttle effect by chemisorption. Furthermore, the defective MoxC can accelerate conversion of LiPSs by a catalytic effect, promoting the polysulfide redox kinetics of the sulfur species and prevent the dissolution of polysulfides. The resultant 77S-MoxC@NC electrode acquired 982 mA h g(-1) after 400 cycles with an ultralow capacity decay rate of 0.14% per cycle.

Automated summary

In this study, a strategy of preparing MoxC@NC was proposed to enhance the performance of Li-S batteries. The hollow structure of MoxC@NC can confine the active materials and facilitate the ion/electrolyte penetration, while the MoxC nanoparticles in the shell can suppress the shuttling effect of LiPSs. Moreover, the defective MoxC can catalytically accelerate the conversion of polysulfides, improving the redox kinetics of sulfur species.