Neutron Diffraction Study on Local Structure of Lithium Storage Intermetallic Compound

Abstract

The local structure of Li_xMg₂Ge, which is a candidate for anode materials of lithium secondary batteries, was investigated using both X-ray diffraction (XRD) and neutron diffraction. It was found that the nearest interatomic distance of the Ge-Mg increases slightly in electrochemically lithiated Mg₂Ge, (or Li_xMg₂Ge), although any other large structural change was not obvious. The evidences suggest that lithium atoms (or ions) accommodate at interstitial sites of the Mg₂Ge lattice to form a solid solution. From the Li-Ge correlation factors observed in the radial distribution functions, furthermore, lithium atoms in the lithiated Mg₂Ge were supposed to occupy the sites equivalent to those of hydrogen atoms in Mg₂NiH_3.9 with an anti-fluorite structure.