Preparation, characterization and stability of Li-ion conducting Li1.5Al0.5Ge1.5(PO4)3 glass-ceramic with NASICON-type structure

A conducting lithium aluminum germanium phosphate (LAGP) glass-ceramic with a formula of Li1.5Al0.5Ge1.5(PO4)3 was synthesized by melt-quenching method and subsequent crystallization at 850 °C for 8 h. The prepared glass-ceramic was characterized using differential scanning calorimetry (DSC), X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and AC impedance techniques. The XRD patterns exhibited the existence of LiGe2(PO4)3 as the dominant phase with a little impurity phase of GeO2. SEM images revealed the presence of large LAGP crystals. A high conductivity of 5.36×10-3 S/cm at 25 °C was obtained for the pristine LAGP. Furthermore, the stability of the LAGP was examined in 1 M LiNO3 aqueous solution by XRD and conductivity measurements. XRD pattern and ionic conductivities of the immersed LAGP showed no change as compared with the pristine LAGP, showing the good stability in aqueous electrolyte and great potential for aqueous lithium-air battery application.