Annealing condition engineering of electrospun iron-titanium oxide nanofibers for enhanced lithium storage performance

Iron/titanium-based oxide compounds have garnered significant attention for their promising applications in lithium-ion batteries. To implement this, a large-scale fabrication technique such as electrospinning has become pivotal for the preparation of one-dimensional iron/titanium-based oxide nanocomposites. However, there exists a notable gap in understanding the influence of annealing conditions on the structure, morphology and electrochemical properties of resultant products. In this work, iron-titanium-based oxide nanofibers are produced via electrospinning followed by subsequent annealing, and the influence of annealing atmospheres on the products is systematically investigated. When annealed at 600°C in an argon atmosphere, the product is carbon nanofibers loaded with FeTiO₃ and Fe₃O₄ nanoparticles (FeTiO₃/Fe₃O₄/CNFs), while annealing in air the product is carbon nanofibers embedded with Fe₂TiO₅ nanoparticles (Fe₂TiO₅/CNFs). Electrochemical tests demonstrate that FeTiO₃/Fe₃O₄/CNFs maintain a capacity of 395.6 mAh g^-1 after 100 cycles at a current density of 0.2 A g^-1, which is higher than that of Fe₂TiO₅/CNFs (174 mAh g^-1) and Fe₃O₄/CNFs (314 mAh g^-1). Moreover, FeTiO₃/Fe₃O₄/CNFs present a remarkable rate capability, possessing a capacity of 212.1 mAh g^-1 at 2.0 A g^-1. This excellent performance is attributed to the synergistic effect between FeTiO₃ and Fe₃O₄ and buffering effect of the carbon fibers. These findings highlight the significant application potential of iron/titanium oxides in the field of electrochemical energy storage.