The synergistic effect of dual substitution of Al and Sb on structure and ionic conductivity of Li7La3Zr2O12 ceramic

Li7La3Zr2O12 (LLZO) with cubic garnet type structure is a promising solid electrolyte. In this work, Li6.925-3xAlxLa3Zr1.925Sb0.075O12 (0 ≤ x ≤ 0.1) electrolytes were prepared by conventional solid-state reaction. The influence of Sb-Al cosubstitution on the structure, microstructure and conductivity of Li7La3Zr2O12 were investigated by X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM) and impedance spectroscopy. Single cubic phase has been achieved for Li6.925-3xAlxLa3Zr1.925Sb0.075O12 (x = 0-0.075). Suitable amount of Al-Sb cosubstitution accelerates densification and improves the ionic conductivity. Li6.775Al0.05La3Zr1.925Sb0.075O12 exhibits highest relative densities (96.7%) and total ionic conductivity (4.10 × 10−4 S/cm at 30 °C).