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

Abstract

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 m²/g, pore volume: 0.112 m³/g). It also exhibited an excellent electrochemical performance with a high reversible capacity (900 mAh/g at 1 A/g), a high coulombic efficiency (∼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.