A systematic study of annealing environment and Al dopant effect on NASICON-type LiZr2(PO4)3 solid electrolyte

Abstract

The ionic conductivity of LiZr2(PO4)3 (LZP), a NASICON-type electrolyte, can be altered by doping, annealing temperature, and pressure. In this study, the rhombohedral framework of Li1+xAlxZr2-x(PO4)3 (LAZP, x = 0.1–0.9) solid electrolyte, for application in Li-air batteries, are synthesized using a facile solid-state reaction. A systematic dual effect of dopant and annealing environment on the grain boundary resistance, ionic conductivity, and ions diffusion are investigated for this electrolyte. With the substitution of Al3+, the rhombohedral solid electrolyte structure synthesized in various environments becomes stable at room temperature due to additional Li+ ions and provides high ionic conductivity. LAZP ionic conductivity is 4 times higher than that of LiZr2(PO4)3 at room temperature due to the formation of a high-temperature-stable phase by Al doping. Additionally, the solid electrolyte properties significantly depended on the synthesis environment; the maximum ionic conductivity and Li-ion mobility are observed for Li1.3Al0.3Zr1.7(PO4)3 solid electrolyte synthesized in an oxygen environment. © 2020, Springer-Verlag GmbH Germany, part of Springer Nature.