Electrochemistry of illusive barbosalite, Fe2+Fe3+2(PO4)2(OH)2: An iron phosphate related to lipscombite structure


Barbosalite, an iron hydroxy-phosphate belonging to the family of Lazulite has been synthesized using hydrothermal route and its electrochemical property is investigated for the first time with respect to Li-ion batteries. The structure, as determined from single-crystal X-ray diffraction data, built up of undulating layers of FeO6 octahedra, consisting of trimers and PO4 tetrahedral units. Magnetic susceptibility measurements show predominant overall anti-ferromagnetic interactions and room temperature 57Fe Mössbauer spectroscopic studies confirm the mixed 3+ and 2+ oxidation states of Fe in the compound. The compound is stable up to 400°C and undergo facile electrochemical lithium insertion. Galvanostatic charge-discharge studies indicate that up to 0.7 lithium ions per formula unit can be inserted at an average voltage of 2.6 V. The barbosalite phase seems to undergo irreversible phase transition upon lithiation as evident from the powder X-ray diffraction pattern of the reduced and oxidized phases.


Physics, Astronomy, and Materials Science

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© The Authors 2019. Published by ECS. This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 License (CC BY, http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse of the work in any medium, provided the original work is properly cited

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Journal of the Electrochemical Society