Tin dispersed in an oxide matrix as negative electrode material for Li-ion batteries

This paper deals with new tin-based composite β-Sn/(CaSiO 3) 0.4 negative electrode materials for Li-ion batteries. The nature of the oxide matrix and of dispersed tin particles has been investigated by X-ray diffraction (XRD), scanning electron microscope (SEM) coupled with energy dispersion spectroscopy (EDS) and Mössbauer spectroscopy by both transmission (TMS) and backscattering (CEMS) mode for bulk and interface characterizations. The electrochemical behaviour of the composite has been studied during Li-reaction processes. Electrochemical investigation and Mössbauer data analyses suggest the formation of Li 7Sn 2 during Li reaction. The reversible mechanism is based on cycling between β-Sn and Li 7Sn 2. An interface composed of CaSn IVSiO 5 and a Sn II species between tin particles dispersed in the CaSiO 3 matrix is responsible of the irreversible capacity observed in this composite during the first discharge.