Berlin 2012 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 17: Poster Session

MM 17.33: Poster

Montag, 26. März 2012, 17:00–19:00, Poster B

Lithium Iron Phosphate as thin film cathode and in all solid-state batteries — •Mathias Köhler, Frank Berkemeier, and Guido Schmitz — Institut für Materialphysik, Westfälische Wilhelms-Universität Münster, Wilhelm-Klemm-Str.10, 48149 Münster, Germany

Lithium Iron Phosphate (LFP) is widely used as a cathode material in conventional lithium ion batteries. In this work, thin films of LFP, exhibiting a thickness between 200 and 500 nm, were prepared by rf-ion beam sputter deposition. The films were characterized by means of X-ray diffraction (XRD), transmission electron microscopy (TEM), cyclic voltammetry (CV), and galvanostatic intermittent titration technique (GITT). The LFP films were deposited on silicon substrates at different temperatures between 400°C and 700°C. In all cases, TEM measurements show smooth and homogeneous layers, and XRD results indicate the desired crystalline structure. For detailed electrical characterisation, an additional metallic current collector (Pt, Au) of about 100 nm was deposited, so the electrochemical functionality of the samples could be investigated. First CV results show that the deposition temperature strongly influences the electrochemical capacity, and that a temperature of around 500°C results in LFP thin films of a maximum storage capacity of about 60 mAh/g. Since the thin films reveal a well-defined thickness, they give the possibility to precisely determine the diffusion coefficient of lithium in LFP by means of GITT. So, the diffusion coefficient as a function of the lithium concentration was determined, using the GITT thin film approach.