Regensburg 2010 – scientific programme

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MM: Fachverband Metall- und Materialphysik

MM 57: Topical Session Battery Materials III

MM 57.2: Talk

Thursday, March 25, 2010, 14:30–14:45, H6

Li ion transport in sputter deposited LiCoO₂ thin films and glassy borate membranes — •Tobias Stockhoff, Tobias Gallasch, and Guido Schmitz — Westfälische Wilhelms-Universität Münster, Institut für Materialphysik, Münster (Westf.), Germany

LiCoO₂ membranes are key components of current battery technology. We investigate sputter-deposited thin films of these materials aiming at the application in all-solid-state thin film batteries. For this, LiCoO₂ films (10 - 200 nm) were deposited onto ITO-coated glass substrates by ion beam sputtering. In addition, a part of these films are coated by an ion-conductive membrane of Li₂O-B₂O₃ glasses in the thickness range of 50 to 300 nm. Structural, chemical and electrical properties of the layers are studied by means of TEM (EELS) and various electrical methods (cyclic voltammetry, chrono-amperometry / -potentiometry).

Since the color of the LiCoO₂ films changes from red-brown to grey during de-intercalation of Li and the substrate as well as the glassy membrane deposited on top are optical transparent, reversible Li de- and intercalation can be directly demonstrated and quantified by a measurement of light transmission through the layered system. Samples coated with an ion-conductive membrane reveal a characteristic delay in switching optical transparency which is due to the slower transport across the membrane. Varying the thickness of the glassy membrane, the d.c. ion-conductivity and permeation through the membrane is determined quantitatively. Using thin membranes in the range of a few tens of nanometers the critical current densities are way sufficient for battery applications.