Multidimensional core-shell nanocomposite of iron oxide-carbon tube and graphene nanosheet: A lithium-ion battery anode with enhanced performance through structural optimization

A novel multidimensional composite of 1D iron oxide (Fe3O4)-carbon tube and 2D graphene nanosheet (GNS) was demonstrated to be used as the anode material for lithium-ion batteries (LIBs). Fe3O4-carbon tube-GNS manifested a unique core-shell composite structure, where the Fe3O4 nanoparticles were embedded in the carbon tube with the GNS. The material characterization confirmed that the Fe3O4 nanoparticles were embedded in the highly graphitized carbon tube with the dispersed GNS. Fe3O4-carbon tube-GNS exhibited a high porosity (surface area: 62.3 m(2)/g, pore volume: 0.112 m(3)/g). It also exhibited an excellent electrochemical performance with a high reversible capacity (900 mAh/g at 1 A/g), a high coulombic efficiency (similar to 100 % for 100 cycles), and good rate capability (491 mAh/g at 5 A/g). The excellent electrochemical performance of our composite is attributed to the suppressed/accommodated volume expansion of Fe3O4 and formation of a stable solid electrolyte interphase (SEI) layer during lithiation/delithiation caused by unique multidimensional composite structure of Fe3O4-carbon tube-GNS with a continuous transport path for electrons and Li+. In addition, such the enhanced lithium storage of our composite is confirmed with the kinetic characterization at various scan rates by analyzing their storage and capacitive contributions.