Effect of Nb5+ doping on the microstructure and conductivity of Li1.125Ta0.875Zr0.125SiO5 electrolyte

• Published in: Journal of alloys and compounds 2022-05, Vol.902, p.163760, Article 163760
• Main Authors: Zhang, Yanzhi, Liu, Shijiu, Zhang, Qian, Ning, Tianxiang, Wang, Xinli, Lu, Anxian
• Format: Article
• Language: English
• Subjects: Ceramic; Ceramics; Conductors; Densification; Diffusion barriers; Doping; Electrochemical analysis; Grain boundaries; Ion transport; Ionic conductivity; Lithium ions; Microstructure; Nb doping; Rechargeable batteries; Solid electrolyte; Solid phases
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2022.163760

•Nb5+-doped Li1.125Ta0.875-xNbxZr0.125SiO5 ceramic electrolytes were prepared.•The microstructure and electrochemical properties of ceramics were discussed in detail.•0.1875 mol Nb5+-doped sample had the best conductivity of 3.521 × 10-5 S/cm at 25 °C.•The ionic conductivity of the 0.1875 mol Nb5+-doped sample is an order of magnitude higher than the original one.•Li1.125Ta0.6875Nb0.1875Zr0.125SiO5 ceramics have the potential used in solid electrolytes. The microstructure and electrochemical properties of Li1.125Ta0.875-xNbxZr0.125SiO5 (x = 0, 0.0625, 0.1875, 0.25, 0.5) ceramics prepared via the solid-phase reaction method were studied. The results reveal that the conductivity of the ceramic specimens at 25 °C increases and then decreases as the Nb increases from 0 to 0.5 mol. 0.1875 mol of Nb doping facilitates the fusion and connection between grains, reduces the number of grain boundaries, leads to densification of the ceramics, decreases the total resistance, and thus increases the conductivity. Moreover, the small structural distortion caused of the discrepancy in ionic radii of Ta5+ and Nb5+ creates more space to accommodate Li ions and promotes the diffusion of Li+, reducing the energy potential barrier for ion transport. The best performing Li1.125Ta0.6875Nb0.1875Zr0.125SiO5 has a conductivity of 3.521 × 10-5 S/cm at 25 °C, with an order of magnitude greater than that of the original sample Li1.125Ta0.875Zr0.125SiO5, reaching 2.288 × 10-4 S/cm at 150 °C and has a minimum activation energy: 0.225 eV. The prepared Li1.125Ta0.6875Nb0.1875Zr0.125SiO5 ceramic is a new type of fast Li-ion conductor with potential for application in all-solid-state batteries.