P-doped Fullerene Films as Coating Materials for Silicon Film Anodes of Lithium Secondary Batteries

Abstract

Phosphorus doped fullerene C60 (P:C60) thin films were introduced as coating materials for silicon film anodes of lithium secondary batteries using a plasma assisted thermal evaporation technique. The P:C60 coated silicon films were then used as anode materials of lithium secondary batteries. The electrochemical characteristics of the coated electrodes were studied by charge discharge tests, cyclic voltammetry and impedance spectroscopy. Electrochemical measurements revealed that the higher coulombic efficiency of 91% and lower irreversible capacity of 298 mAhg-1on the first cycle were observed for the P:C60 coated silicon electrodes in comparison with the bare silicon case. In addition, the stable cyclic property and high capacity retention after the 30th cycle were demonstrated. All above mentioned results were attributed to the improved conductivity due to the presence of C60 coating layer which might contribute to the faster transfer of Li-ions at the electrode/electrolyte interface.