Influence of Mg-deficiency on the functional properties of magnesium ferrite anode material

Non-stoichiometric magnesium ferrites (MgxFe2O4) with different deficiency values (x = 0.5, 0.95 and 1) have been prepared applying the sol gel method. The resulting samples have been investigated using X-ray powder diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrare...

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Bibliographic Details
Published in:Solid state ionics 2019-11, Vol.341, p.115042, Article 115042
Main Authors: Heiba, Zein K., Sanad, M.M.S., Mohamed, Mohamed Bakr
Format: Article
Language:English
Subjects:
Anode materials
Anodes
Diffraction
Electrochemical analysis
Electrode materials
Ferrites
Fourier transforms
Grain size
Lattice vacancies
Li-ion battery
Magnesium
Magnesium ferrite
Magnesium ferrites
Photoelectrons
Scanning electron microscopy
Sol-gel processes
X ray photoelectron spectroscopy
X ray powder diffraction
X-ray diffraction
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Summary:Non-stoichiometric magnesium ferrites (MgxFe2O4) with different deficiency values (x = 0.5, 0.95 and 1) have been prepared applying the sol gel method. The resulting samples have been investigated using X-ray powder diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared (FTIR) and X-ray photoelectron spectroscopy (XPS). The influence of Mg-deficiency on the electrochemical properties of magnesium ferrites has been explored. Rietveld analysis of XRD indicated that Mg deficiency causes a redistribution of cations among the tetrahedral and octahedral sites associated with the existence of vacancies and a reduction in both lattice parameter and grain size. XPS analysis has revealed the existence of iron ions (Fe3+) only and confirmed the existence of deficiency of both magnesium Mg2+ and oxygen O2– ions. The electrochemical measurements indicated improved performance; Mg-deficiency yields better cyclic performance during the first 50 cycles, however, the specific discharge capacity of Mg0.5Fe2O4 cell is dramatically decreased during the subsequent 50 cycles. •Mg-deficiency in magnesium ferrite•XPS confirmed the existence of both Mg2+ and O2– vacancies.•Mg-deficiency yields better cyclic performance during the first 50 cycles.
ISSN:0167-2738
1872-7689
DOI:10.1016/j.ssi.2019.115042