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

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 degrees 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 x 10(-5) S/cm at 25 degrees C, with an order of magnitude greater than that of the original sample Li1.125Ta0.875Zr0.125SiO5, reaching 2.288 x 10(-4) S/cm at 150 degrees 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. (C) 2022 Elsevier B.V. All rights reserved.

Automated summary

The microstructure and electrochemical properties of Li1.125Ta0.875-xNbxZr0.125SiO5 ceramics prepared via the solid-phase reaction method were investigated. The conductivity of the ceramics increased and then decreased as the Nb doping concentration increased. Nb doping at 0.1875 mol facilitated the fusion and connection between grains, reducing the number of grain boundaries and increasing the conductivity. The structural distortion caused by the discrepancy in ionic radii of Ta5+ and Nb5+ allowed for more accommodation of Li ions and promoted Li+ diffusion, reducing the energy potential barrier for ion transport. The Li1.125Ta0.6875Nb0.1875Zr0.125SiO5 ceramic exhibited the highest conductivity, making it a potential candidate for all-solid-state batteries.