Preparation of New Lithium Ion Conductor, thio-LISICON, from Mechanical-Milled Amorphous Li2S-P2S5 System

Abstract

A new lithium ion conductor of the thio-LISICON (Lithium SuperIonic CONductor) was found in the Li2S-P2S5 system. The thio-LISICON phase of Li3+5xP1-xS4 (0≤x≤0.2) was prepared from mechanical-milled amorphous sulfide powders and the structural properties were characterized by X-ray diffraction measurements. The electrical properties were studied by AC impedance spectroscopy. In the composition range 0≤x≤0.2, Li3.35P0.93S4 (x=0.07 in Li3+5xP1-xS4) showed the highest conductivity value and the lowest activation energy at room temperature. The extra lithium ions in Li3PS4 created by partial substitution of P5+ for Li+ led to the large enhancement in ionic conductivity.