Original electrochemical mechanisms of CaSnO3 and CaSnSiO5 as anode materials for Li-ion batteries

Calcium stannate (CaSnO3) and malayaite (CaSnSiO5) were synthesized by means of a high temperature solid-state reaction. Their crystal structures and morphologies were characterized by X-ray diffraction (XRD) and Scanning Electron Microscopy; their electrochemical properties were analyzed by galvanostatic tests. The amorphization of the initial electrode materials was followed by XRD. The first discharge of the oxides CaSnO3 and CaSnSiO5 shows a plateau at low potential, which is due to the progressive formation of Li–Ca–Sn and/or Li–Sn alloys as shown by 119Sn Mössbauer spectroscopy. The results reveal similar electrochemical mechanisms for CaSnO3 and CaSnSiO5 but they completely differ from those related to SnO2.

Graphical abstract119Sn Mössbauer spectra at the end of the first discharge of CaSnO3 (dashed line) and CaSnSiO5 (solid line) anodes for Li-ion batteries. Inset shows that relative amounts of Sn(0) based alloys formed during the first discharge are similar for CaSnO3 and CaSnSiO5 pristine materials.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► CaSnSiO5 and CaSnO3 as anode materials for Li-ion batteries. ► X-ray diffraction and Mössbauer spectroscopy, to explain the electrochemical mechanisms. ► Similar mechanisms for the two compounds but different from those of SnO2 due to Ca.