Ion Transport in Plasticized Li1.5Al0.5Ge1.5(PO4)3 Based Electrolytes

Abstract

The development of an efficient devices for energy storage, conversion, and transmission is one of the key priority areas today. At the center of these activities is the development of all-solid-state high-energy and high-power lithium-ion batteries.Our research is focused on the study of ion transport in a plasticized-by-ionic-liquid composite membrane formed by electrophoretic deposition (EPD). The EPD membrane comprises above 85% of high-ion-conductivity ceramic matrix Li1.5Al0.5Ge1.5(PO4)3 (LAGP) and less than 15% polyethyleneimine (PEI). The EPD rate and morphology of the membrane were characterized by SEM, TOFSIMS and DSC methods. 0.3M LiTFSI–PYR14TFSI was infused in the membrane to form a quasi-solid electrolyte. The complex, non-Debye dielectric response of the quasi-solid electrolyte, tested over the temperature and frequency ranges of (-140oC) to (+100oC) and 10-2 – 106 Hz, has been described in terms of several distributed relaxation processes separated by different frequency and temperature ranges. While at low temperatures, the main contribution is from LAGP, in the middle- and high-temperature regions, the superposition of a few non-Arrhenius processes is observed. Relaxation is perturbed by clear phase transition related to melting of the ionic liquid. Different scales of the ionic transport and corresponding relaxation of the apparent dipole moment in the materials are discussed.