A systematic study of annealing environment and Al dopant effect on NASICON-type LiZr 2 (PO 4 ) 3 solid electrolyte

The ionic conductivity of LiZr 2 (PO 4 ) 3 (LZP), a NASICON-type electrolyte, can be altered by doping, annealing temperature, and pressure. In this study, the rhombohedral framework of Li 1+x Al x Zr 2-x (PO 4 ) 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 Al 3+ , 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 LiZr 2 (PO 4 ) 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 Li 1.3 Al 0.3 Zr 1.7 (PO 4 ) 3 solid electrolyte synthesized in an oxygen environment.