Carbothermal synthesis of Sn-based composites as negative electrode for lithium-ion batteries

The composite [Sn-BPO4/xC] to be used as negative electrode material for the storage of electrochemical energy was obtained by dispersing electroactive tin species onto a BPO4 buffer matrix by carbothermal reduction of a mixture of SnO2 and nanosized BPO4. This composite material was thoroughly characterized by X-ray diffraction, Scanning Electron Microscopy, Sn-119 Mossbauer spectroscopy and Raman spectroscopy. The electrochemical tests of this new material highlight its very interesting electrochemical properties, i.e., a discharge capacity of 850 mAh g-1 for the first cycle and reversible capacity around 585 mAh g(-1) at C/5 rate. These electrochemical performances are attributed to the very high dispersion and stabilisation of tin metal particles onto the BPO4 matrix. The irreversible capacity observed for the first charge/discharge cycle is due the reduction of interfacial Sn-II species and to the passivation of the anode surface by liquid electrolyte decomposition (formation of the SEI layer). (C) 2010 Elsevier B.V. All rights reserved.