Evolution of the negative electrode (tin/silicate) for Li-ion batteries studied by 119Sn Mössbauer spectroscopy

A novel tin composite Sn/CaSiO3 for the anode of Li-ion batteries was prepared by solid-state reaction. The CaSiO3 matrix was synthesized by a sol-gel route. The crystalline structures and morphology were determined by X-ray diffraction (XRD) and 119Sn Mössbauer spectroscopy; the electrochemical properties were evaluated by galvanostatic charge and discharge. The results obtained show that the Sn/CaSiO3 composite presents very interesting electrochemical performances in terms of specific capacity in the first discharge (591 mAh/g) and a good reversibility due to both the formation of an interface between active and inactive materials and the reversible formation of LixSn alloys. We have also highlighted, by 119Sn Mössbauer spectroscopy, the various tin species constituting the material of the starting electrode, as well as the chemical evolutions occurring during the discharge and the charge of the electrode.