Conductivity of 70Li2S·30P2S5 glasses and glass–ceramics added with lithium halides

• Lithium halides were added to 70Li2S·30P2S5 glass and glass–ceramic.
• Structure and electrical conductivity were examined for glasses and glass–ceramics.
• Conductivities of the glasses increased with increasing lithium halide content.
• All glass–ceramics contained Li7P3S11 crystals with high conductivity.
• Addition of LiBr to the glass–ceramic was effective for increasing conductivity.

Glasses and glass–ceramics of (100 − y)(0.7Li2S·0.3P2S5)·yLiX (mol%) (0 ≤ y ≤ 20, X = F, Cl, Br, and I) were synthesized using mechanical milling and subsequent heat treatment. The conductivities of glasses added with LiBr and LiI improved with increasing lithium halide contents. Larger halide ions produced higher conductivity. All glass–ceramic samples contained Li7P3S11 crystals. The Li7P3S11 crystal crystallinity was degraded with increasing lithium halide content. The composition dependence of conductivities differed depending on the added lithium halides. Incorporation of LiBr was most effective for increasing the 70Li2S·30P2S5 glass–ceramic conductivity.