Phase Changes in Electrochemically Lithiated Silicon at Elevated Temperature

Samples of with average compositions of , , and as well as the metastable crystalline alloy were prepared electrochemically. The phase changes in these samples at elevated temperature were explored using differential scanning calorimetry and X-ray diffraction. The amorphous phase present in the and samples transformed first, near , to , instead of the expected based on the phase diagram. The amorphous component in the sample apparently has a higher average lithium content and transformed to both and near . At higher temperatures all the samples transformed into the thermodynamically stable phases expected based on their average compositions and the phase diagram. The metastable crystalline apparently transforms into thermodynamically stable phases in one step.