Regensburg 2016 – wissenschaftliches Programm
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MM: Fachverband Metall- und Materialphysik
MM 31: Functional materials I: Supercapacitors and batteries I
MM 31.4: Vortrag
Mittwoch, 9. März 2016, 11:00–11:15, H53
7Li NMR studies of lithium ion dynamics in SiOC anode materials — •Michael Haaks1, Ralf Riedel2, and Michael Vogel1 — 1Institut für Festkörperphysik, Technische Universität Darmstadt, Germany — 2Institut für Materialwissenschaft, Fachgebiet Disperse Feststoffe, Technische Universität Darmstadt, Germany
Rising energy demand makes it important to improve the performance of lithium ion batteries. For this purpose it is important to understand the dynamics of lithium ions, in particular, in heterogeneous materials, which are used in modern strategies for material optimization. We combine 7Li NMR spin-lattice relaxation, line-shape, and stimulated-echo analyses to investigate lithium ionic motion in a polymer-derived silicon oxycarbide (SiOC) ceramic in lithiated and delithiated compounds on a broad timescale. We find that the large variety of lithium environments results in broad distributions of correlation times for the jump motion of the lithium ions. Moreover, we observe that the lithium ionic jumps are, on average, faster in the lithiated than in the delithiated compound at ambient temperatures. On the other hand, the lithiated SiOC has a higher temperature dependence of this jumps so that the difference in the ionic mobilities is reduced upon cooling. Finally, we show that heating to 400 K leads to irreversible changes of the prepared lithiated and delithiated samples.