Synthesis of Superionic Conductive Li1+x+yAlxSiyTi2-xP3-yO12 Solid Electrolytes

Commercial lithium-ion batteries using liquid electrolytes are still a safety hazard due to their poor chemical stability and other severe problems, such as electrolyte leakage and low thermal stability. To mitigate these critical issues, solid electrolytes are introduced. However, solid electrolytes have low ionic conductivity and inferior power density. This study reports the optimization of the synthesis of sodium superionic conductor-type Li1.5Al0.3Si0.2Ti1.7P2.8O12 (LASTP) solid electrolyte. The as-prepared powder was calcined at 650 degrees C, 700 degrees C, 750 degrees C, and 800 degrees C to optimize the synthesis conditions and yield high-quality LASTP powders. Later, LASTP was sintered at 950 degrees C, 1000 degrees C, 1050 degrees C, and 1100 degrees C to study the dependence of the relative density and ionic conductivity on the sintering temperature. Morphological changes were analyzed using field-emission scanning electron microscopy (FE-SEM), and structural changes were characterized using X-ray diffraction (XRD). Further, the ionic conductivity was measured using electrochemical impedance spectroscopy (EIS). Sintering at 1050 degrees C resulted in a high relative density and the highest ionic conductivity (9.455 x 10(-4) S cm(-1)). These findings corroborate with the activation energies that are calculated using the Arrhenius plot. Therefore, the as-synthesized superionic LASTP solid electrolytes can be used to design high-performance and safe all-solid-state batteries.