Graphene-Wrapped Graphitic Carbon Hollow Spheres: Bioinspired Synthesis and Applications in Batteries and Supercapacitors

Inspired by the egg-like yolk-shell structure, a novel kind of graphene-wrapped graphitic hollow carbon spheres (G-graphitic HCS) was designed and fabricated by iron-catalyzed carbonization of double-coated polystyrene (PS) spheres. Herein, a thin carbon shell and hollow, hierarchically porous G-graphitic HCS facilitate ionic transport, while also providing more active sites for the storage of ions. Both graphitic components result in a seamless and highly efficient transmission pathway for electrons. Thus, G-graphitic HCS demonstrate admirable multifunctions in energy-storage devices, including lithium batteries, sodium batteries, and supercapacitors. It delivers an unprecedentedly high initial discharge capacity of 2007 mAhg(-1) at 0.1 Ag-1, and preserves 92.4% of the initial charge capacity after 100 cycles in a prototype lithium half-cell. The present concept may shed light on designing the key materials for next-generation energy-storage devices.