Preparation and enhancement of ionic conductivity in Al-added garnet-like Li_6.8La₃Zr_1.8Bi_0.2O₁₂ lithium ionic electrolyte

Abstract

Garnet-like Li_6.8La₃Zr_1.8Bi_0.2O₁₂ (LLZBO) + x mol.% Al₂O₃ (x = 0, 1.25, 2.50) lithium ionic electrolytes were prepared by conventional solid state reaction method under two different sintering temperatures of 1000°C and 1100°C. XPS, induced coupled plasma optical emission spectrometer (ICP-OES), XRD and AC impedance spectroscopy were applied to investigate the bismuth valance, lithium concentration, phase structure and lithium ionic conductivity, respectively. Electrical measurement demonstrated that ionic conductivity of Al-added LLZBO compounds could be obviously improved when the sample sintering temperature increased from 1000°C to 1100°C. The highest ionic conductivity 6.3×10⁻⁵ S/cm was obtained in the LLZBO−1.25%Al sample sintered at 1100°C, in consistent with the lowest activation energy 0.45 eV for the lithium ion migration. The mechanism related with good ionic conductivity in the Al-added LLZBO sample was attributed to the lattice distortion induced by the partial Al substitution at Zr sites, which is helpful to improve the migration ability of Li ions in lattice.

Keywords

garnet lithium electrolyte / cubic Li₇La₃Zr₂O₁₂ / AC impedance / ionic conductivity / activation energy

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Acknowledgements

This work was financially supported by the National Natural Science Foundation of China (Grant Nos. 11374299, 11405203 and 51401203).

RIGHTS & PERMISSIONS

2014 Higher Education Press and Springer-Verlag Berlin Heidelberg