Elaborately Designed Micro–Mesoporous Graphitic Carbon Spheres as Efficient Polysulfide Reservoir for Lithium–Sulfur Batteries

Abstract

Hybrid micro–mesoporous graphitic carbon spheres (M-MGCSs) featuring ordered mesoporous graphene-like cores and uniform microporous carbon shells are designed by transformation of self-assembled Fe3O4 nanoparticle supraparticles and are used as an efficient, dual spatially confined sulfur reservoir for lithium–sulfur (Li–S) batteries. Such rationally designed M-MGCSs synergistically combine the merits of micro- and mesoporous carbons when used as the sulfur host in Li–S batteries: the core having interconnected spherical mesopores of 9.0 nm provides sufficient space for loading S8 molecules, while the shell having micropores of 0.6 nm can entrap only small S2–4 molecules, which are converted into electrolyte-insoluble polysulfides during discharge, minimizing the outward diffusion of long-chain polysulfides from the core. These advantageous structural features, combined with the highly graphitic nature and mesoscale spherical morphology of M-MGCSs, enable Li–S cathodes with greatly improved performance ev...