Liquid-phase synthesis of 100Li3PS4-50LiI-xLi3PO4 solid electrolytes

Abstract

Lithium-ion highly conducting 100Li3PS4-50LiI-xLi3PO4 (0 ≤ x ≤ 20 mol%) solid electrolytes were successfully prepared by liquid-phase synthesis using ethyl propionate as the reaction medium. Li3PO4 could be inserted into the Li3PS4-LiI structure (up to x = 20) without any noticeable segregated peak in the resulting X-ray diffraction patterns. 31P NMR revealed the formation of PO2S2 and POS3 units, which confirmed that Li3PO4 reacted with Li2S-P2S5 system to form Li3PO4-xSx. Solid electrolyte with x = 10 exhibited the highest conductivity of about 8.5 × 10−4 Scm−1 at room temperature.