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

Novel self-organized Ti₁/₂Sn₁/₂O₂ nanotubes can be produced by the electrochemical anodization of co-sputtered Ti-Sn thin-films. Combined X-ray photoelectron spectroscopy and (119)Sn Mössbauer spectroscopy of pristine samples evidenced the octahedral substitution of Sn(4+) for Ti(4+) in the TiO₂ structure. In addition to the improved lithium storage behaviour of the Ti₁/₂Sn₁/₂O₂ nanotubes, ex situ(119)Sn Mössbauer spectroscopy of cycled electrodes has sufficiently confirmed that no decomposition of the Ti₁/₂Sn₁/₂O₂ 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 Ti₁/₂Sn₁/₂O₂ nanotubes in the 1 ≤ U/V ≤ 2.6 voltage range.