Interfacial properties of fullerene coated silicon film as an anode material for lithium secondary batteries: effect of coating layer thickness

Silicon thin films with thickness of about 300 nm were coated by fullerene thin film with different thickness (50-200 nm) using plasma assisted thermal evaporation technique. The fullerene coated silicon films were then characterized as anode materials of lithium secondary batteries. The interfacial properties of the electrodes coated with fullerene film of different thicknesses have been studied using impedance spectroscopy and compared with those of uncoated silicon electrodes. An enhancement of the performances of the coated electrodes in terms of reduced solid electrolyte interface (SEI) and charge transfer resistances has been found. As the thickness of fullerene is increased, the coated electrodes demonstrated a smaller initial irreversible capacity and a more reduced charge transfer resistance. However, there was a thickness limit that gave a larger interfacial resistance than that of bare silicon film anodes.