At present, lithium batteries conquer much attention because of their widespread applications ranging from portable electronics to transportation and grid storage. The next-generation safe and robust lithium batteries require highly conducting solid electrolytes with excellent chemical stability with elemental Li and high voltage cathodes. Garnet-type metal oxides such as Li₅La₃Ta₂O₁₂, Li₆La₂BaTa₂O₁₂, and Li₇La₃Zr₂O₁₂ are promising candidates because of their high bulk ionic conductivity, low electronic conductivity and high electrochemical stability (up to 6V/Li).^1-3 It is critical to understand the ion transport mechanism in these garnet-type oxides with respect to change in lithium content and temperature to further develop highly conducting practical solid electrolytes for next generation Li batteries. The present study reports effect of Y-doping for Ta in Li₅La₃Ta₂O₁₂ on structural, chemical, morphological and electrical properties. Analysis of crystal structure and electrical properties are performed using powder X-ray diffraction, NMR, and ac impedance spectroscopy to understand the Li ion migration pathways in Li_5+2xLa₃Ta_2-xY_xO₁₂ (0.05 ≤ x ≤ 0.75).^4,5 The x = 0.75 member of Li_5+2xLa₃Ta_2-xY_xO₁₂ exhibits the highest conductivity of 10^-4 Scm^-1 at 23 ºC. In addition, high stability in aqueous solution makes Li_5+2xLa₃Ta_2-xY_xO₁₂ suitable to use as Li protection layer in lithium-aqueous batteries.³ 

References

1. V. Thangadurai, H. Kaack, and W. Weppner, J. Am. Ceram. Soc., 86, 437 (2003).

2. R. Murugan, V. Thangadurai and W. Weppner, Angewandte Chemie International Edition, 46, 7778 (2007).

3. V. Thangadurai, S. Narayanan, and D. Pinzaru, Chem. Soc. Rev. 43, 4714 (2014).

4. S. Narayanan, F. Ramezanipour, and V. Thangadurai, Inorg. Chem. 54, 6968 (2015).

5. A.K. Baral, S. Narayanan, F. Ramezanipour, and V. Thangadurai, Phys. Chem. Chem. Phys. 16, 11356 (2014).