Lithiation of Anodic Magnetite−Hematite Nanotubes Formed on Iron

This study represents progress in comprehending the storage of lithium-ion within 1D nanotubes. It achieves this through an analysis of the differential capacity plots (d(Q−Q0) · dE-1), complemented by in situ Raman spectroscopy observations. The surface morphology and cross-section of the specimens were analysed using a Zeiss Sigma 500 field emission scanning electron microscope (SEM) instrument. An accelerating voltage of 1kV was employed to investigate the morphology. The phase present in the anodic films was determined using a Rigaku RINT-2000 X-ray diffractometer with CuKα radiation. To analyse thin films, the grazing incidence XRD mode was utilized to reduce the influence of the substrate material. The anodic iron oxide microelectrode was subjected to electrochemical testing as negative electrodes in a half-cell PAT-cell (EL-cell) within a lithium-ion battery (LIB) setup. In situ Raman spectroscopy measurements were conducted utilizing the In situ Raman ECC-OPTO cell.Mechanistic studies, conducted both in situ and ex-situ, unveiled the quasi-reversible reduction of iron oxide to metallic iron facilitated by the formation of Li2O during electrochemical Li+ insertion.