Preparation of Li1.5Al0.5Ge1.5(PO4)3 solid electrolytes via the co-precipitation method

Abstract

ABSTRACTLi1.5Al0.5Ge1.5(PO4)3 (LAGP) is prepared through co-precipitation and sintered at various temperatures (650 ~ 900°C). Impurity formation is affected by the sintering temperature. Although impurity formation is observed in all the samples, it becomes more prominent at high sintering temperatures. The crystallinity of LAGP increased with the sintering temperature as evidenced by SEM observations, which show that the edges of the grains become sharper with increases in the sintering temperature. However, the formation of pores is also observed in the pellets sintered at 850°C and 900°C. As a result, the highest Li ion conductivity (7.8 × 10−5 S cm−1) is obtained when the sintering temperature is 800°C due to the high crystallinity of LAGP and absence of pore formation. This conductivity value is comparable to previously reported values and LAGP synthesis temperature is 400°C lower than required by the melt-quenching method. The co-precipitation method is a promising method for the preparation of LAGP solid electrolytes at low temperatures.