Three-dimensional structures and lithium-ion conduction pathways of (Li2S)x(GeS2)100 − x superionic glasses

•We visualized the local structures of the Li2S–GeS2 glasses using RMC modeling.•We visualized the conduction pathways of Li ions in the Li2S–GeS2 glasses.•We directly compared topology of the conduction pathways using activation energy.

The conduction pathways of Li ions in (7Li2S)x(GeS2)100 − x glasses (x = 40, 50, and 60) were predicted and visualized by combining reverse Monte Carlo (RMC) modeling and the bond valence sum (BVS) approach, using synchrotron X-ray and time-of-flight neutron diffraction data. The conduction pathways of the Li ions could be classified into four grades, according to the magnitude of |ΔV(Li)|: (I) |ΔV(Li)| < 0.04 (i.e., relatively stable regions for the Li ions), (II) 0.04 ≤ |ΔV(Li)| < 0.07, (III) 0.07 ≤ |ΔV(Li)| < 0.10, and (IV) 0.10 ≤ |ΔV(Li)| < 0.13; here, |ΔV(Li)| is the mismatch of the BVS for Li ions, V(Li). These were used to obtain a clear understanding of the movement of the Li ions in the (7Li2S)x(GeS2)100 − x glasses. It was also found that there is a definite relationship between the topology of the conduction pathways of the Li ions and the activation energy, Ea, of the electrical conduction.