Structural and electrochemical aspects of Mn substitution into Li2FeSiO4 from DFT calculations
2010 (English)In: Computational materials science, ISSN 0927-0256, Vol. 47, no 3, 678-684 p.Article in journal (Refereed) Published
DFT calculations are presented which probe the effect of low-concentration Mn substitution of the Fe-sites in Li2FeSiO4: the promising new and potentially cheap cathode material for upscaled Li-ion battery applications. The LixFe0.875Mn0.125SiO4 System investigated could be achieved by replacing 12.5% of the Fe-sites in 2 x 2 x 1 and 2 x 2 x 2 supercells by Mn ions. The evolution of Bader charges and partial densities of states (DOS) have been followed under a stepwise delithiation process. A clear structural distortion is seen to occur at the Mn-site on delithiation, suggesting possible structural instability. Oxidation of Mn beyond 3+ is calculated to occur at potentials in excess of 4.7 V, implying that oxidation of well separated (>10 angstrom) low-concentration Mn ions to Mn4+ is energetically unfavourable in the LixFe0.875Mn0.125SiO4 structure. This, together with previous DFT results for higher levels of Mn substitution into Li2FeSiO4, indicates that capacity increase in Li2Fe1 (-) yMnySiO4 through a > 1 electron redox reaction may not be so readily attainable in practice, either for high or low Mn concentrations.
Place, publisher, year, edition, pages
2010. Vol. 47, no 3, 678-684 p.
Lithium iron silicate, Manganese substitution, Electronic structure, Electrochemistry, Density functional theory
Research subject Chemistry with specialization in Inorganic Chemistry
IdentifiersURN: urn:nbn:se:uu:diva-138040DOI: 10.1016/j.commatsci.2009.10.008ISI: 000274222000009OAI: oai:DiVA.org:uu-138040DiVA: diva2:378796