Graphene-doped carbon/Fe3O4 porous nanofibers with hierarchical band construction as high-performance anodes for lithium-ion batteries

Porous graphene-doped carbon/Fe3O4 (GN@C/Fe3O4) nanofibers are synthesized via in-situ electro-spinning and subsequent thermal treatment for use as lithium-ion battery anode materials. A polyacrylonitrile (PAN)/polymethyl methacrylate (PMMA) solution containing ferric acetylacetone and graphene oxide nariosheets is used as the electrospinning precursor solution. The resulting porous GN@C/Fe3O4 nanofibers show unique dark/light banding and a hierarchical porous structure. These nanofibers have a Brunauer-Emmett-Teller (BET) specific surface area of 323.0 m(2)/g with a total pore volume of 0.337 cm(3)/g, which is significantly greater than that of a sample without graphene and C/Fe3O4 nanofibers. The GN@C/Fe3O4 nanofiber electrode displays a reversible capacity of 872 mAh/g at a current density of 100 mA/g after 100 cycles, excellent cycling stability, and superior rate capability (455 mA/g at 5 A/g). The excellent performance of porous GN@C/Fe3O4 is attributed to the material's unique structure, including its striped topography, hierarchical porous structure, and inlaid flexible graphene, which not only provides more accessible active sites for lithium-ion insertion and high-efficiency transport pathways for ions and electrons, but also accommodates the volume change associated with lithium insertion/extraction. Moreover, the zero-valent iron and graphene in the porous nanofibers enhance the conductivity of the electrodes. (C) 2017 Elsevier Ltd. All rights reserved.