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

• 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
• ISSN: 0167-2738; 1872-7689
• DOI: 10.1016/j.ssi.2019.115042

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.