Structural Study of Electrochemically Lithiated Si

The structure, chemical composition, and electronic state of the LixSiy alloy, which formed on the Si(111) surface by electrochemical lithiation of Si, were investigated in detail by soft x-ray emission spectroscopy (SXES) combined with scanning electron microscopy (SEM) and by surface x-ray diffraction (SXRD) using synchrotron radiation (SR) as an X-ray source. Electrochemically lithiated Si(111) (EC-LixSiy) consists of three layers; from top layer to bottom, a single-crystalline of Li15Si4 (sc- Li15Si4) alloy, which was epitaxially grown on Si(111), an amorphous Li15/13Si4 (a-Li15/13Si4) alloy, and a mixed phase of a-Li15/13Si4 alloy and crystalline Si (c-Si).