Thermal stability and reduction of iron oxide nanowires at moderate temperatures

Background: The thermal stability of iron oxide nanowires, which were obtained with a hard template method and are promising elements of Li-ion based batteries, has been investigated by means of thermogravimetry, infrared and photoemission spectroscopy measurements. Results: The chemical state of the nanowires is typical of the Fe₂O₃ phase and the stoichiometry changes towards a Fe₃O₄ phase by annealing above 440 K. The shape and morphology of the nanowires is not modified by moderate thermal treatment, as imaged by scanning electron microscopy. Conclusion: This complementary spectroscopy–microscopy study allows to assess the temperature limits of these Fe₂O₃ nanowires during operation, malfunctioning or abuse in advanced Li-ion based batteries.