Berlin 2012 – scientific programme

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MM: Fachverband Metall- und Materialphysik

MM 17: Poster Session

MM 17.29: Poster

Monday, March 26, 2012, 17:00–19:00, Poster B

Chemical diffusion in lithium titanate thin films — •Fabian Wunde, Frank Berkemeier, and Guido Schmitz — Institut für Materialphysik, Münster, Germany

Lithium titanate (LTO) is used as an anode material in lithium ion batteries, as it reveals both, electronic as well as Li-ion conductivity. Both conductivities and the capability to reversibly intercalate/deintercalate lithium, strongly depends on the lithium diffusivity of the material, which is difficult to obtain in case of powder material, because of its porous structure. Therefore, due to their well defined structure and the absence of e.g. conductive binder, ion-beam sputtered thin film electrodes of LTO are appropriate for diffusion studies, as they give access to the diffusivity of lithium in pure LTO. In this work we prepared thin films of LTO by reactive rf-ion beam sputtering and carefully proofed the structure of the films by X-ray diffraction and transmission electron microscopy. Afterwards, we applied galvanostatic intermittent titration technique (GITT) technique to determine the chemical diffusion coefficient, i.e. by evaluating the electrical potential of the LTO layer vs. lithium, when applying a pulsed current signal. Due to the thin film geometry of our samples, it was possible to reliably evaluate the GITT results by assuming the thin approach and to obtain the lithium diffusivity in LTO as a function of the lithium concentration.