Is it possible to prepare olivine-type LiFeSiO 4?

• Published in: Solid state ionics Vol. 179; no. 27; pp. 1758 - 1762
• Main Authors: Arroyo y de Dompablo, M.E., Gallardo-Amores, J.M., García-Martínez, J., Morán, E., Tarascon, J.-M., Armand, M.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 2008
• Subjects: First principles calculations; High pressure; Lithium batteries; Silicates; First principles calculations; Lithium batteries; Silicates; High pressure
• ISSN: 0167-2738; 1872-7689
• DOI: 10.1016/j.ssi.2008.03.023

Silicates LiMSiO 4 are potential positive electrode materials for lithium ion batteries. In this work we analyse from first principles calculations the relative stability of possible LiFeSiO 4-polymorphs within four structural types. Olivine-LiFeSiO 4 is predicted to be more stable than the LiFeSiO 4 prepared by delithiation of Li 2FeSiO 4; the latter being the only LiFeSiO 4 compound reported so far. Attempts to prepare olivine-LiFeSiO 4 from a mixture of reactants at ambient pressure (600–1100 °C) resulted in a mixture of quartz-SiO 2, Li 2SiO 3, LiFe 5O 8 and LiFeSi 2O 6 phases. Conducting the reaction under HP conditions (40 kbar) leads to the formation of LiFeSi 2O 6 as a majority phase, regardless the nature of the reactants/precursors. First principles calculations indicate that the preparation of the olivine-LiFeSiO 4 is thermodynamically hindered due to the competition with the more stable LiFeSi 2O 6 pyroxene, in the range of pressure/temperature investigated.