Formation Process of 60Li₂S⋅40SiS₂ Amorphous Materials with High Lithium Ion Conductivity Prepared by Mechanical Milling

Abstract

The formation process of 60Li₂S⋅40SiS₂ lithium ion conducting materials prepared by mechanical milling was investigated by X-ray diffraction (XRD), ²⁹Si magic angle spinning nuclear magnetic resonance (MAS NMR), X-ray photoelectron spectroscopy (XPS), and scanning electron microscope (SEM) observation. Upon mechanical milling for only 1h 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^-4S·cm^-1 at room temperature.