Comparative studies of mechanical and electrochemical lithiation of intermetallic nanocomposite alloys for anode materials in Li-ion batteries

Intermetallic composite compounds, i.e. Ag52Sn48, Ag36.4Sb15.6Sn48 and Ag36.4Fe15.6Sn48, were lithiated by mechanical grinding in order to compare with electrochemical lithiation of corresponding nanocomposite alloy with respect to lithium diffusion between active host materials. The structures were analyzed with synchrotron X-ray powder diffraction using the Rietveld method. The composite materials consist of Ag3Sn and Sn and in the case of adding Sb also SbSn. The alloys and the lithiated compounds have a strong crystallographic relation; the metal atoms form a more or less cubic closed-packed three-dimensional network with interstitial sites available for the Li atoms. Upon lithiation, the binary alloys form compounds with partial compositions, i.e. Ag2 − xLi1 + xSn and Li2 + xSn1 − xSb. The similar lithium diffusion mechanisms for mechanical and electrochemical lithiation and how it can be useful in designing new intermetallic composite alloys for Li-ion batteries were high-lighted.