Formation process of 60Li2S•40SiS2 amorphous materials with high lithium ion conductivity prepared by mechanical milling

The formation process of 60Li(2)S.40SiS(2) lithium ion conducting materials prepared by mechanical milling was investigated by X-ray diffraction (XRD), Si-29 magic angle spinning nuclear magnetic resonance (MAS NMR), X-ray photoelectron spectroscopy (XPS), and scanning electron microscope (SEM) observation. Upon mechanical milling for only Ih most SiS2 particles reacted with Li2S crystals to form partially amorphous materials. Such material reacted with the residual Li2S crystals by further mechanical milling treatments, until the composition of the amorphous part became the nominal one. Since the fully amorphous part became dominant in a continuously percolated structure, the ion conductivity could be greatly improved from 10(-10) to 10(-4) S.cm(-1) at room temperature.