Effect of TeO2 sintering aid on the microstructure and electrical properties of Li1.3Al0.3Ti1.7(PO4)3 solid electrolyte

NASICON-type solid electrolyte Li1.3Al0.3Ti1.7(PO4)3 (LATP) has become an excellent substitute for organic liquid electrolytes due to its high ionic conductivity and exceptional air stability. However, its application is limited by its poor sintering characteristics and high grain boundary resistance. In this study, TeO2 was introduced into LATP as a sintering aid to promote its sintering, and its properties were measured by XRD, SEM, XPS, EIS and dilatometry. The results show that the addition of TeO2 can form eutectic liquid phase in LATP ceramic pellets during sintering, thus effectively promoting particle sintering. Not only the grain size was greatly increased, but also grain boundary and pore defects were reduced. With the help of TeO2, the performance of LATP is greatly improved when sintered at only 750 °C, the relative density and total ionic conductivity reached 90.64% and 0.207 mS/cm, respectively. The highest total ionic conductivity of 0.279 mS/cm and the highest relative density of 93.81% were obtained when sintered at 800 ℃ and 950 ℃, respectively. However, due to the volatilization of Li and Te at high temperature, the relative density and total ionic conductivity of LATP with TeO2 added sintered at high temperature have only a small increase compared to that without addition. In conclusion, this study provides a feasible scheme for improving LATP performance.