Electrochemical performance of Sn-BPO4 negative electrode materials synthesized via carbothermal reduction

Abstract

A new approach was developed to disperse "electroactive" Sn into an "inactive" matrix for application as negative electrode for the electrochemical storage energy. The [Sn(BPO4)xCy] composite material was obtained by carbothermal reduction of SnO2 into a BPO4 matrix. The condition of synthesis was optimized using DSC-TGA analysis. This composite material was characterized by X-ray diffraction, Scanning Electron Microscopy, 119Sn Mössbauer spectroscopy and electrochemical tests. The results show these new materials present very interesting electrochemical performances; the discharge capacity for the first cycle was 650mAh.g-1 and the reversible capacity was 500 mAh.g-1 at C/5 rate. These improved electrochemical results are due to good in situ dispersion of Sn particles into the matrix. The irreversible capacity observed for the first charge/discharge cycle is due to interfacial SnII reduction and passivation of the anode surface by liquid electrolyte decomposition (SEI layer).

Keywords

• sn-based composites
• lithium-ion batteries
• carbothermal reduction
• negative electrode
• mössbauer spectroscopy
• electrochemistry