Analysis of the structure and degree of crystallisation of 70Li2S-30P2S5 glass ceramic

Heat treatment of Li2S-P2S5 glasses to transform the glass to a glass ceramic enhances the ionic conductivity by precipitating a Li7P3S11 metastable crystalline phase with high ionic conductivity. Although the precipitated phase is identical, the conductivity achieved varies depending on the heat treatment conditions. Solid-state P-31 MAS NMR spectroscopy to investigate the structure of the glass ceramic in this study revealed a strong correlation between the ionic conductivity and the degree of crystallisation, in which the conductivity of the glass ceramic increased with increasing proportion of metastable Li7P3S11 phase.