Effects of Heat Treatment and Additive LiF on the Properties of Solid-State Electrolyte of Li1.5Al0.5Ge1.5(PO4)3

A solid electrolyte of LAGP [Li1.5Al0.5Ge1.5(PO4)(3)] contained 0.5 wt% LiF was prepared by using low-volatile raw materials. The effects of different heat treatment conditions (750-900 degrees C, 4-10 h) and additive (LiF) on the ionic conductivity, structural morphology, and crystal transformation process were investigated in detail. EIS (electrochemical impedance spectroscopies) showed that the ionic conductivity of LAGP contained 0.5 wt% LiF had a highest value of 3.17 x 10(-4) S cm(-1) with low activation energy (0.31 eV) after treating 825 degrees C for 6 h, more than LAGP of 2.45 x 10(-4) S cm(-1). DSC analysis and SEM images indicated that adding a small amount of LiF to LAGP not only can lower the glass transition temperature (from 513 degrees C to 507 degrees C) and crystallization temperature (from 622 degrees C to 605 degrees C), but also can modify the grain boundary and increase the relative density of LAGP (from 95.8% to 97.7%).

Automated summary

The addition of a small amount of LiF to LAGP solid electrolyte can significantly improve the ionic conductivity and structural properties, as well as have a significant impact on the crystal transformation process.