119Sn Mössbauer spectroscopy study of the mechanism of lithium reaction with self-organized Ti1/2Sn1/2O2 nanotubes

Abstract

Novel self-organized Ti_1/2Sn_1/2O₂ nanotubes can be produced by the electrochemical anodization of co-sputtered Ti–Sn thin-films. Combined X-ray photoelectron spectroscopy and ¹¹⁹Sn Mössbauer spectroscopy of pristine samples evidenced the octahedral substitution of Sn⁴⁺ for Ti⁴⁺ in the TiO₂ structure. In addition to the improved lithium storage behaviour of the Ti_1/2Sn_1/2O₂ nanotubes, ex situ¹¹⁹Sn Mössbauer spectroscopy of cycled electrodes has sufficiently confirmed that no decomposition of the Ti_1/2Sn_1/2O₂ structure occurred, and that no Li–Sn phase was formed during the discharge, corroborating that the electrochemical reaction is due exclusively to Li⁺ insertion into the Ti_1/2Sn_1/2O₂ nanotubes in the 1 ≤ U/V ≤ 2.6 voltage range.