Electrochemical properties of fullerene coated silicon thick film for anode material of lithium secondary batteries

摘要

Silicon has been considered as alternative anode materials for rechargeable lithium batteries since it has large theoretical capacity and works well at low operating voltages. One main constraint preventing the silicon from the commercial application is the rapid capacity fading due to the huge volume changes during the charge-discharge reaction [1-2]. In the previous work, the surface modification of silicon thin film anodes with approximated thickness of 300 nm was proposed by using fullerene films as a coating material [3]. It was found that in the case of silicon thin film, its electrochemical properties were significantly improved by fullerene coating. However, the thick silicon film demonstrated worse cycling performance and depressed rate capability due to the larger volume effect and the lower electrical conductivity [4]. In the present work, fullerene film was deposited onto the surface of silicon thick film anodes using plasma assisted thermal evaporation technique by varying the plasma power. It is expected that the fullerene coating layer can play the same role as in the case of silicon thin film to minimize the effect of volume expansion hence the electrochemical performance will be enhanced.