Study of the electrochemical performance of sputtered Si1-xSnx films

Amorphous alloys of Si and Sn exhibit large specific and volumetric capacities when cycled electrochemically vs. lithium. Combinatorial films of a-Si1-xSnx in the range 0 < x < 0.45 have been prepared by magnetron sputtering. These films have been analyzed for structure, composition, and electrochemical performance. The composition range was chosen to ensure that the films would be amorphous. No sharp peaks are seen in the cyclic voltammograrns of these films, indicating homogeneous insertion of lithium. Reversible capacities as high as 3500 mAh/g have been attained and capacity retention is generally good. There appears to be no correlation between composition and capacity retention in the range 0 < x < 0.45 in a-Si1-xSnx. (C) 2004 The Electrochemical Society.