Effect of cobalt addition to NASICON-type Li1.3Al0.3Ti1.7(PO4)3 (LATP) on its sintering behavior and electrical properties

Co ions as a sintering aid were electrostatically adsorbed on the surface of negatively-charged NASICON-type solid electrolyte Li1.3Al0.3Ti1.7(PO4) (3) (LATP) particles using cobalt nitrate hexahydrate in an ethanol solvent. The Co element-modified LATP (Co-LATP) showed the maximum relative density of 80% at the firing temperature of 800(o)C. This value was comparable to the relative density of LATP with no Co addition fired at 1000(o)C. It was observed that the addition of Co promoted neck growth between the LATP particles. During the heating process, the cobalt ions diffuse into the LATP and form a reaction phase, such as LiCoPO4 (LCP), on the surface of the LATP. The electrical conductivity of Co-LATP fired at 800(o)C increased from the Co addition amount of 0.0 to 0.5 wt%, demonstrating that the addition of cobalt contributed to the increase in the conductivity. The addition of an appropriate amount of Co ions to the LATP is effective in order to decrease the process temperature and increase the conductivity.