Preparation and characterization of superionic conducting Li7P3S11 crystal from glassy liquids

Abstract

Superionic Li+ ion conducting Li7P3S11 crystal was prepared by crystallization of the 70Li2S·30P2S5 (mol %) glass and melt. In the case of crystallization of the 70Li2S·30P2S5 glass, the crystallized electrolyte heated at 360°C for 1 h showed a conductivity of 4.1 × 10−3 S cm−1 at room temperature. In the case of crystallization from the 70Li2S·30P2S5 melt, a single phase of the Li7P3S11 crystal was obtained by crystallization of the melt at 700°C for 48 h and then quenching in ice water. The crystallized electrolyte showed the conductivity of 2.9 × 10−3 S cm−1 at room temperature. The precipitated crystal depended on the heat treatment temperature, holding time, and cooling rate. In both crystallization processes from the glass and melt, the Li7P3S11 crystal was precipitated as a primary phase from supercooled liquids and thus the superionic conducting Li7P3S11 crystal is a high temperature phase at the composition 70Li2S·30P2S5.