Browsing by Author "Dominko, R"

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    Li2FeSiO4 cathode material: the structure and electrochemical performances
    (Materials Research Society of Serbia, 2014-09-01) Jugović, D; Milović, M; Mitrić, M; Ivanovski, VN; Avdeev, M; Jokić, B; Dominko, R; Uskoković, D
    Monoclinic Li2FeSiO4 that crystallizes in P21/n space group was investigated as a potential cathode material for lithium-ion batteries. A combined X-ray diffraction and Mössbauer spectroscopy study was used for the structural investigation. It was found that the crystal structure is prone to an “antisite” defect, the one in which the Fe ion and the Li ion exchange places. This finding was also confirmed by the Mössbauer spectroscopy. In order to obtain composites of Li2FeSiO4 and carbon, several synthesis techniques that use different carbon sources were involved. Electrochemical performances were investigated through galvanostatic charge/discharge tests. Discharge curve profile did not reflect a two-phase intercalation reaction (no obvious voltage plateau) due to the low conductivity at room temperature. © 2014 Materials Research Society of Serbia
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    Structural study of monoclinic Li2FeSiO4 by x-ray diffraction and Mössbauer spectroscopy
    (Elsevier, 2014-11-01) Jugović, D; Milović, M; Ivanovski, VN; Avdeev, M; Dominko, R; Jokić, B; Uskoković, D
    A composite powder Li2FeSiO4/C is synthesized through a solid state reaction at 750 °C. The Rietveld crystal structure refinement is done in the monoclinic P21/n space group. It is found that the crystal structure is prone to “antisite” defect where small part of iron ion occupies exclusively Li(2) crystallographic position, of two different lithium tetrahedral positions (Li(1) and Li(2)). This finding is also confirmed by Mössbauer spectroscopy study: the sextet evidenced in the Mössbauer spectrum is assigned to the iron ions positioned at the Li(2) sites. A bond-valence energy landscape calculation is used to predict the conduction pathways of lithium ions. The calculations suggest that Li conductivity is two-dimensional in the (101) plane. Upon galvanostatic cyclings the structure starts to rearrange to inverse βII polymorph. © 2014, Elsevier B.V.