Dependences of ionic conductivity and activation energy on germanium content in superionic Li1.4Al0.4GexTi(1.6−x)(PO4)3 solid electrolytes

Herein, to improve the ionic conductivities of Li1.4Al0.4Ti1.6(PO4)3 (LATP) solid-state electrolytes and establish the optimal Ge content to yield a high lithium-ion conductivity, Ti4+ is partially substituted with Ge4+ to yield Li1.4Al0.4GexTi(1.6−x)(PO4)3 (LAGTP, x = 0.1, 0.2, 0.3, and 0.4). The LAGTP solid electrolytes are synthesized using a facile solution-based method. Further, the obtained material is calcined and sintered at 800 and 900 °C, respectively. The structural properties of the LAGTP ceramic powders are thoroughly investigated, and the dependences of the ionic conductivity and activation energy on Ge content are also explored. The LAGTP (x = 0.1) solid electrolyte exhibits the highest total ionic conductivity (1.05 × 10–3 S/cm) at 25 °C and the lowest activation energy (0.237 eV), which are far superior to those of the conventional LATP solid electrolytes. Therefore, LAGTP solid electrolytes are potential candidates for use in developing safer high-performance all-solid-state batteries.