Amorphous Si thin films have been prepared using radio-frequency magnetron sputtering. Cu nanodots of 2-10 nm in diameter were sputter deposited on the surface of Si films. The Si films modified with Cu nanodots (n-Cu/Si) were used as anodes for lithium-ion batteries. The performances of the n-Cu/Si anodes with different thickness of Si films, 120 and 1000 nm, were characterized and compared. The Cu nanodots can greatly improve the cycling stability. The amount of capacity fading was 66% after 150 cycles for the thinner Si films (120 nm), and was over 90% after 50 cycles for thicker films (1000 nm). For the n-Cu/Si films, the amount of capacity fading was 33% for thin films and 45% for thicker films. (C) 2008 The Electrochemical Society.