Effect of cryolite as sintering-aids on the structure and conductivity of Li0.25La0.25NbO3 ceramic solid electrolytes for solid state lithium batteries

The sintering temperature of oxidizing solid electrolytes is usually much higher than that of electrode materials. This study introduced cryolite into Li0.25La0.25NbO3 ceramic matrix as a sintering additive to reduce its sintering temperature and improve the electrical properties. The properties of Li0.25La0.25NbO3–cryolite composites were measured by XRD, SEM, AC-impedance, and DC-polarization. The results show that the addition of cryolite can effectively promote sintering for Li0.25La0.25NbO3 ceramic and the performance of Li0.25La0.25NbO3 ceramic is improved when sintered at only 1050 °C. The total ionic conductivity reached 1.37 × 10−5 S cm−1, which is comparable to samples without cryolite that sintered at 1100 °C. The contribution of electronic conductivity in cryolite-modified Li0.25La0.25NbO3 ceramic to the total conductivity is negligible. A feasible scheme for decreasing sintering temperature and improving sintering and electrical property for Li0.25La0.25NbO3 ceramic solid electrolytes is provided in this work. [Display omitted]