Preparation of Li4.4GexSi1−x alloys by mechanical milling process and their properties as anode materials in all-solid-state lithium batteries

Li4.4GexSi1−x alloys were prepared by use of a high-energy ball-milling process. The Li4.4GexSi1−x alloys formed a solid solution over the whole composition range of 0≤x≤1. Those alloys were isomorphic with an Li15Ge4 crystalline phase that had a D86 structure belonging to a space group I4¯3d. The lattice constants of the alloys were increased with an increase in the compositional parameter x. The Li4.4GexSi1−x alloys were investigated as negative electrode materials for all-solid-state lithium batteries with an inorganic solid electrolyte a-60Li2S·40SiS2 (mol%). Among the obtained alloys, the Li4.4Ge0.67Si0.33 alloy showed the largest specific capacity of 190 mA h g−1 and good charge–discharge reversibility.