Refined Transportation of Li Ions in Ge Doped Li1+xGexLa2–xTiO12 Solid Electrolytes for all Solid State Lithium Ion Batteries

The compound Li1+xGexLa2–xTiO12 was prepared using a conventional solid-state reaction method, where Germanium (Ge) was substituted at the lithium site with varying Ge content (x) from 0.05 to 0.15. X-ray diffraction (XRD) analysis confirmed the formation of the conductive cubic phase. Scanning electron microscopy (SEM) was used to examine the surface morphology. The lattice parameters of the synthesized sample were also calculated. The sample with 0.10 Ge showed the highest ionic conductivity at room temperature. The maximum conductivity recorded was 9.24 × 10–2 S/cm at an operating temperature of 350°C. This one-order magnitudes increase in ionic conductivity at room temperature makes the 0.10 Ge ceramic samples a promising candidate for solid electrolytes. Different amounts of GeO2 were used to synthesize Ge-doped LiLaTiO (Ge-LLTO) perovskites via solid-state reactions, aimed at producing Li-ion conductive electrolytes for all-solid-state rechargeable lithium batteries. These samples were tested at various temperatures to optimize their ionic conductivity, especially at lower temperatures. The addition of GeO2 has improved both the sinterability and Li ion conductivity of the perovskite solid electrolyte. Also, the vibrational and morphological studies provide an impact on the effective yield obtained through this research. The grain-boundary resistance decreased from 312 Ω at 150°C to 105 Ω at 350°C, indicating improved Li⁺ ion transport with increasing temperature. Arrhenius analysis yielded an activation energy of −0.31 eV, confirming thermally activated lithium-ion conduction and enhanced ionic conductivity in the Ge-substituted LLTO (x = 0.10) electrolyte. This study determined the optimal sample for sintering at 1250°C by evaluating the electrolyte’s microstructure and electrochemical properties, along with a study of germanium doping.