The fast lithium-ion conducting oxides Li3xLa2/3-xTiO3 from fundamentals to application

The development of fast lithium conductors is attracting much attention because of their potential applications in electrochemical devices such as high-energy lithium ion batteries, electrochromic systems, supercapacitors and electrochemical sensors. Among the lithium electrolyte ceramics, the lithium lanthanum titanates, Li3xLa2/3-xTiO3, a disordered oxide with perovskite structure, have attracted much attention because of their high conductivity, of the order of 10(-3) S cm(-1) at room temperature, for x = 0.11. The crystallographic structure of the solid solution, prepared by conventional solid-state chemistry, will be described. The dynamics of the lithium ions in Li3xLa2/3-xTiO3 has been investigated by conductivity spectroscopy in the wide frequency range from 1 Hz to 1 GHz, and by Li-7 NMR spin-lattice relaxation measurements (T-1 and T-1 rho) in the temperature range from 150 K to 600 K. Furthermore, the preparation of nanomaterials (20-30 nm) by a modified Pechini-type in-situ polymerizable method will be presented. Finally, we will show the ability of the ceramic to be used as pH sensor. (c) 2007 Elsevier B.V. All rights reserved.