Influence of phosphorus sources on lithium ion conducting performance in the system of Li2O–Al2O3–GeO2–P2O5 glass–ceramics

•The effect of phosphorus sources on LAGP glass–ceramics' conductivities is studied.•Highly pure NASICON phase is prepared when H3PO4 is used as a phosphorus source.•The highest conductivity is obtained with H3PO4 as a phosphorus source.

NASICON-type structure lithium ion conductors have been considered as promising solid electrolytes due to its very high Li+-ion conductivity and chemical stability. In this paper, NASICON-type structured Li1.5Al0.5Ge1.5(PO4)3 (LAGP) glass–ceramics are prepared from crystallization of glass powders, which are obtained by a simple melt-quench method. NH4H2PO4, H3PO4, P2O5 and H3PO4&Al(PO3)3 are used as phosphorus sources, respectively. The obtained LAGP glass–ceramics are systematically characterized with X-ray diffraction, field emission scanning electron microscopy, differential scanning calorimetry and AC impedance spectroscopy. The different impurities are formed depending on the phosphorus sources, which further influence the microstructure. As a result, the lithium ion conductivity is significantly affected by the phosphorus sources. The highest conductivity of 5.21 × 10− 4 S·cm− 1 is obtained when H3PO4 is used as the phosphorus source under optimum conditions.