Structural and electrochemical properties of fullerene-coated silicon thin film as anode materials for lithium secondary batteries

By performing a plasma evaporation technique, fullerene C-60 was used as a coating material onto a silicon thin film anode for lithium secondary batteries. The effect of the plasma power (20W, 100W and 200W) in the plasma coating process on the structural and electrochemical properties of the fullerene C-60-coated silicon anode was then studied by means of Raman spectroscopy, Fourier transform infra red (FTIR) spectroscopy, scanning electron microscopy (SEM), energy dispersive X-ray (EDX) spectroscopy and charge/discharge tests. The Raman and FTIR analysis showed that the polymeric phase of fullerene C60 was formed during the deposition operation and that the fullerene monomers were polymerized to a greater extent at a high plasma power operation (200W). Furthermore, the fullerene C-60-coated silicon electrode obtained at a plasma power of 200W exhibited excellent electrochemical performance with a specific capacity of more than 2000 mAh g(-1). The stable polymeric phase of fullerene C60 was found to be the main factor enhancing the electrochemical performance of the fullerene-coated silicon anode. (C) 2008 Elsevier B.V. All rights reserved.