Synthesis and sintering of Li1.3Al0.3Ti1.7(PO4)3 (LATP) electrolyte for ceramics with improved Li+ conductivity

The key material for all-solid-state batteries is the solid electrolyte. In concepts with high energy density and capacity, this Li+ conductive component has two essential functions: Substituting the liquid electrolyte in the cathode and separating the cathode from the anode. Therefore, the research on Li+ conductive solids is one important step to realize high performing all-solid-state batteries. In this study, two different methods of preparing Li1.3Al0.3Ti1.7(PO4)3 (LATP) powder are compared with regard to particle size, phase purity and sintering properties. As top-down method the melting and as bottom-up route the sol-gel synthesis are applied. Spark Plasma Sintering (SPS) is used to densify the powders at temperatures between 800 and 1000 °C. The densities, the microstructures and the Li+ conductivities are compared in relation to the preparation method. Using sol-gel synthesis, the phase purity of the LATP powder is higher compared to the top-down route. The milling of the synthesized powder increases the homogeneity of the resulting microstructure and enhances the ionic conductivity. Room temperature Li+ conductivity of 1 × 10−3 S cm-1 with a high density of 99.4% was achieved with the milled, sol-gel synthesized powder at a sintering temperature of 1000 °C.