Influence of mixing technique on properties of Li1.3Al0.3Ti1.7(PO4)3 solid electrolyte prepared by the solid-state reaction - A comparison of dry 3D mixing technique with wet ball-milling

Li1.3Al0.3Ti1.7(PO4)3 (LATP) NASICON(Na Super Ion Conductive)-type solid electrolyte is prepared using conventional wet ball-milling and dry 3D mixing techniques to investigate the influence of mixing technique on properties of LATP. The mixing techniques influence impurity formation of calcined LATP powder. Thus, sintering behavior of the calcined powders is also affected by the mixing technique, i.e. LiTiPO5 formation is confirmed in the ball-milling samples and Li-ion conductive Li4P2O7 is main impurity in the 3D mixing samples. The influence is not limited to impurity formation. Uniform grains are observed in the 3D mixing pellet, contrarily, non-uniform sintering occurs in the ball-milling sample. As a result, the 3D mixing pellets demonstrate higher Li-ion conductivity than the ball-mill samples. The dry 3D mixing technique, which can omit drying process, is promising for LATP preparation owing to simplification of preparation process and a formation of high Li-ion conductive LATP pellets. Also, this study clearly shows that the mixing techniques affect ionic conductivity of the sintered LATP significantly, emphasizing importance of mixing procedure in the solid-state reaction.