Dr. V. Thangadurai thanks the German Academic Exchange Service (DAAD), Bonn, Germany for financial support in the framework of the Guest Professorship program.
Li6ALa2Ta2O12 (A = Sr, Ba): Novel Garnet-Like Oxides for Fast Lithium Ion Conduction†
Article first published online: 13 JAN 2005
Copyright © 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Advanced Functional Materials
Volume 15, Issue 1, pages 107–112, January, 2005
How to Cite
Thangadurai, V. and Weppner, W. (2005), Li6ALa2Ta2O12 (A = Sr, Ba): Novel Garnet-Like Oxides for Fast Lithium Ion Conduction. Adv. Funct. Mater., 15: 107–112. doi: 10.1002/adfm.200400044
- Issue published online: 13 JAN 2005
- Article first published online: 13 JAN 2005
- Manuscript Accepted: 18 JUN 2004
- Manuscript Received: 3 FEB 2004
- Electrical resistivity;
- Lithium ion batteries
Oxides with the nominal chemical formula Li6ALa2Ta2O12 (A = Sr, Ba) have been prepared via a solid-state reaction in air using high purity La2O3, LiOH·H2O, Sr(NO3)2, Ba(NO3)2, and Ta2O5 and are characterized by powder X-ray diffraction (XRD) in order to identify the phase formation and AC impedance to determine the lithium ion conductivity. The powder XRD data of Li6ALa2Ta2O12 show that they are isostructural with the parent garnet-like compound Li5La3Ta2O12. The cubic lattice parameter was found to increase with increasing ionic size of the alkaline earth ions (Li6SrLa2Ta2O12: 12.808(2) Å; Li6BaLa2Ta2O12: 12.946(3) Å). AC impedance results show that both the strontium and barium members exhibit mainly a bulk contribution with a rather small grain-boundary contribution. The ionic conductivity increases with increasing ionic radius of the alkaline earth elements. The barium compound, Li6BaLa2Ta2O12, shows the highest ionic conductivity, 4.0×10–5 S cm–1 at 22 °C with an activation energy of 0.40 eV, which is comparable to other lithium ion conductors, especially with the presently employed solid electrolyte lithium phosphorus oxynitride (Lipon) for all-solid-state lithium ion batteries. DC electrical measurements using lithium-ion-blocking and reversible electrodes revealed that the electronic conductivity is very small, and a high electrochemical stability (&#62; 6 V/Li) was exhibited at room temperature. Interestingly, Li6ALa2Ta2O12 was found to be chemically stable with molten metallic lithium.