Regensburg 2019 – scientific programme
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MM: Fachverband Metall- und Materialphysik
MM 26: Materials for Energy Storage and Conversion
MM 26.4: Talk
Wednesday, April 3, 2019, 15:45–16:00, H43
Analytical Transmission Electron Microscopy studies of LiNixMnyCo1−x−yO2 and Silicon electrode materials for lithium ion batteries — •Ardavan Makvandi1, Martin Peterlechner1, Simone Casino2, Tobias Gallasch2, Martin Winter2, and Gerhard Wilde1 — 1Institute of Materials Physics, University of Münster, Münster, Germany — 2MEET Battery Research Center, University of Münster, Münster, Germany
The modification of state-of-the-art electrode materials by nanostructured coatings is one approach to optimize crucial parameters for application, such as electronic conductivity or mechanical stability of the raw materials. In general, interfaces (active material/coating; electrode surface/electrolyte) determine the local Li ion transport kinetics and finally the electrochemical cell performance in terms of cycling stability or capacity retention. Therefore, it is necessary to study the structure and chemistry of electrodes and electrode/electrolyte interfaces. In this work, the structural and chemical evolution in the bulk and surface regions of LiNixMnyCo1−x−yO2 (NMC) and silicon thin film electrodes after lithiation and de-lithiation processes is studied using scanning transmission electron microscopy (STEM) imaging, electron diffraction, and electron energy loss spectroscopy (EELS). In case of EELS quantification, the Mn-M edge overlaps with the Li-K signal hindering the direct measurement of the lithium content. Nonetheless, by using EELS, the valence states of transition metals (Mn, Co, and Ni) and consequently an indirect measurement of the lithium ion distribution in the NMC cathode materials can be obtained.