Alloys of Si with elements such as Zn may exhibit large specific and volumetric capacities when cycled electrochemically vs lithium. Combinatorial films of Si1-xZnx in the range 0 < x < 0.62 have been prepared by magnetron sputtering. These films have been analyzed for structure, composition, and electrochemical performance. The composition of the film is found to have a large impact on cycling performance and phases formed during charge/discharge cycling. Reversible capacities as high as 3000 mAh/g have been attained with good capacity retention for compositions having capacities of about 1000 mAh/g. In situ X-ray diffraction was performed for two compositions to determine which phases are formed during the insertion of Li. (c) 2005 The Electrochemical Society.