Products of lithium interaction with nanostructured oxides SnO2-TiO2 and mechanism of charge-discharge of electrodes in a lithium-ion battery

Products of lithium interaction with thin-film nanostructured SnO 2 -TiO 2 (ST) oxides are studied with the aid of x-ray diffraction analysis and Moessbauer spectroscopy on the 119 Sn nuclei. Electrochemical properties of a series of the ST electrodes with different concentrations of TiO 2 varied from 0 to 20 mol % are also examined. It is concluded that the specific feature of the charge-discharge mechanism of the ST electrodes is a significant participation of oxygen in reversible reactions during insertion and extraction of lithium as compared with an alloying mechanism of operation of tin-containing anodes. The leading role in this is played by titanium oxide. Remaining stable towards reduction by lithium, it facilitates the holding of the neighboring layers of SnO 2 in a nanodisperse state and in an oxidized state. The effect of a decrease in the capacity degradation in modified TiO 2 electrodes, which is discovered in this work, is attributed to the hampering of the growth of nanocrystallites of β-Sn by interlayers of tin and titanium oxides mentioned above.