Mechanisms of electrochemical activity in lithium powersources based on nanocomposites of FeF3 / Fe2O3

V. Moklyak1, А. Hrubiak1, A. Koveria2, О. Svietkina2

1G.V. Kurdyumov Institute for Metal Physics of the N.A.S. of Ukraine, Kyiv, Ukraine

2Dnipro University of Technology, Dnipro, Ukraine

Coll.res.pap.nat.min.univ. 2020, 62:177-186


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Goal. The regularities of the formation of nanostructured states of iron oxides and fluorides are established. The mechanisms of the flow of electrochemical current-forming reactions in lithium current sources with cathodes based on them have been investigated.

Research methodology is based on the use of the following methods: X-ray analysis, Mössbauer spectroscopy, scanning electron microscopy, differential thermal and thermogravimetric analysis, adsorption porometry, cyclic voltammetry, chronopotentiometry, impedance spectroscopy. For mathematical processing, modeling and interpretation of the experimental results, the following software was used: Univem MS 7.01, FullProf, PowderCell 2.4, FindIt 1.3.3, Diamond 3.2i, ZView-2, FRA-2.

Research results. The pattern of formation of nanostructured states of iron oxides and fluorides have been determined. The mechanisms of flow of electrochemical current-forming reactions in lithium current sources with cathodes based on their were disclosed. Relationships between synthesis conditions, structural-phase state and morphological characteristics of synthesized materials and operational parameters of corresponding models of lithium current sources were established.

Scientific novelty. It is established that the hematite phase α-Fe2O3 in nanocomposites FeF3/Fe2O3 acts as a structural stabilizing agent and is passive during structure-forming processes in the corresponding lithium current sources. At deep discharge up to 0.5 V, the phase α-Fe2O3 involvement in interstitial structural processes with subsequent amorphization of structures and change of oxidation states of iron ions from +3 to +2 was recorded.

Practical value. The mechanisms of formation of nanostructured states of iron oxides and fluorides and the relationship between the conditions of production and properties were established. The formed final products are the scientific basis for further development of technological schemes for the synthesis of a wide range of compounds of transition metals in the nanostructured state. The obtained results can be used in the field of electrochemical energy to create industrial prototypes of power supplies and to further optimize the functional properties of iron fluorides.

Keywords: iron oxide, iron trifluoride, nanostructured state, nanocomposite, lithium power sources, electrochemistry, Faraday process


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