1-D nanostructure comprising porous Fe₂O₃/Se composite nanorods with numerous nanovoids, and their electrochemical properties for use in lithium-ion batteries

Novel 1-D nanostructures composed of porous Fe₂O₃/Se composite or subsequently formed hollow Fe₂O₃ nanorods were introduced. Carbon nanofibers embedded with FeSe₂ needle-like nanorods were prepared via the selenization of electrospun nanofibers. During the oxidation process, the faster diffusion rate of Fe ions (76 pm in size) relative to that of the Se ions (184 pm in size) resulted in nanoscale Kirkendall diffusion mechanism, thus forming the 1-D nanostructure comprising nanorods composed of Se/voids/Fe₂O₃ as an intermediate. The complete conversion of FeSe₂ into Fe₂O₃ and the combustion of C, which caused necking between the nanorods, resulted in a 1-D nanoarchitecture composed of hollow Fe₂O₃ nanorods. The discharge capacity during the 400^th cycle of the 1-D nanostructures comprising Fe₂O₃/Se composite nanorods was 1456 mA h g^-1 at a current density of 1.0 A g^-1. The high structural stability of this unique architecture during repeated lithium insertion/deinsertion processes resulted in superior lithium-ion storage performance.