The interest for solid-state batteries as a post-lithium-ion battery technology has been revamped in the recent years. New solid materials can enable improved safety by removing of conventional organic electrolytes. Solid electrolytes present numerous intrinsic properties, such as high ionic conductivity and chemical stability.
My recent research activities performed during the Ph.D. were mainly focused on the modification of the synthesis conditions for a series of ceramic oxides. The explored materials included NASICON electrolytes, such as Li1+xAlxTi1−x(PO4)3 (LATP), and garnets like Li5La3Bi2O12 (LLBO) and Li7La3Zr2O12 (LLZO). The experiments performed on the materials revolved around the use of the hot-pressing technique for the sintering of ceramic pellets. This method has been proven effective in increasing the global compactness of the ceramic, which reflects in improved ionic transport and higher conductivities. Furthermore, a compact electrolyte layer is more resistant to the phenomenon of dendrite evolution, which can severely affect the life cycle of the battery.
Several approaches were attempted, including elemental doping and incorporation of sintering aids to decrease the formation temperature of the final structures. The formation mechanism of the electrolytes was investigated using in situ XRD to identify the evolution of the product phases based on the temperature. A proper tuning of the working conditions is shown to lead to an optimized particle size which reflects on a better densification and an overall improvement of the electrochemical performance.