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

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 Fe 3 O 4 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 S 8 molecules, while the shell having micropores of 0.6 nm can entrap only small S 2–4 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 even at high sulfur areal loadings.