Ionic conductivities of various GeS2-based oxy-sulfide amorphous materials prepared by melt-quenching and mechanical milling methods

Abstract

We have previously explored the Li2S + GeS2 + GeO2 system to determine the specific effect of added GeO2 to a base 0.5Li2S + 0.5GeS2 glass composition. In this new study, we report the conductivities of these Li2S + GeS2 + GeO2 glasses over their full glass forming range to more fully optimize the ionic conductivity. In addition to this study of bulk glasses, we have also studied the effect of creating powders of the bulk glasses and compared the conductivities of the bulk glasses to those of compacted powders. This latter study is relevant due to the fact that in most battery applications powders are the form of choice in forming battery stacks. Since we used the mechanical milling technique to produce the powders, we further extended this study to determine the extent to which the amorphous range could be expanded using the mechanical milling technique. Having access to these extended compositional range materials, we were able to extend all examinations of the role of composition, powder size, and compaction of the sample on the conductivity and we compared these results to those of the bulk glass samples.