Characterization of Li2S-SiS2-LixMOy (M=Si, P, Ge) amorphous solid electrolytes prepared by melt-quenching and mechanical milling

The oxysulfide amorphous materials in the systems 95(0.6Li(2)S(.)0.4SiS(2))(.)5Li(x)MO(y) (M = Si, P, and Ge) were prepared by melt-quenching and mechanical milling techniques. These amorphous materials exhibited high conductivity over 10(-4) S cm(-1) at room temperature, a lithium transport number of unity, and a wide potential window of 10 V. The solid-state cells with the oxysulfide amorphous materials as solid electrolytes worked as lithium secondary batteries and exhibited excellent cycling performance over 100 times. The local structure of the mechanically milled amorphous materials containing Li4SiO4 was similar to that of the corresponding melt-quenched glasses, in which the SiS4 and SiOS3 tetrahedral units were mainly present. The SiOnS4-n (n = 1, 2, 3) tetrahedral units were formed in the case of the addition of Li4SiO4 and Li4GeO4 to the base sulfide system, while these units were not present in the addition of Li3PO4. We have concluded that the reactivity of Lic(x)MO(y) derived from its basicity affected the structure and formation process of the oxysulfide materials prepared by mechanical milling. (C) 2002 Elsevier Science B.V. All rights reserved.