Porous graphene frame supported silicon@graphitic carbon via in situ solid-state synthesis for high-performance lithium-ion anodes

Abstract

The synthesis of graphene-based composite materials for Li-ion batteries using an in situ growing technique is first proposed in this work. Graphene frame supported silicon@graphitic carbon granules were obtained through a one-step solid-state reaction using iron phthalocyanine (FePc) and silicon nanoparticles (SiNPs) as the precursors. Nitrogen-doped graphene was grown in situ around the SiNPs by pyrolyzing and re-carbonizing FePc, and a cross-linked graphene frame network was gradually formed. Simultaneously, SiNPs were wrapped by a thin graphitic carbon layer, and the strong interconnections between the graphene, graphitic carbon and SiNPs led to a spontaneous self-assembly process, resulting in the formation of μm scale granules with available nanoporosities and irregular channels. The self-assembled granules with excellent electrical conductivity can effectively accommodate the volume change of the SiNPs during the repeating discharge–charge processes, therefore high capacity, long cycle life, high Coulombic efficiency and superb rate capability have been realized. The synthesis strategy is facile, safe, low-cost and can be easily industrialized, providing a broadly applicable route for the in situ synthesis of more functional graphene-based composite materials.