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Suche nach „[V.] [Epp]“ hat 7 Publikationen gefunden
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    MobilNachhaltigTC Plattling MoMo

    Vortrag

    A. Dunst, Michael Sternad, V. Epp, M. Wilkening

    Fast Li Self-Diffusion in Amorphous Li-Si Electrochemically Prepared from Semiconductor Grade, Monocrystalline Silicon — Insights from Spin-Locking Nuclear Magnetic Relaxometry

    Poster presentation

    20th International Conference on Solid State Ionics, Keystone, CO, USA

    MobilNachhaltigTC Plattling MoMo

    Zeitschriftenartikel

    J. Langer, V. Epp, Michael Sternad, M. Wilkening

    Diffusion-induced 7Li NMR relaxation of layer-structured tin disulphide — Li diffusion along the buried interfaces in Li0.17SnS2

    Solid State Ionics, vol. 276, no. August, pp. 56-61

    DOI: 10.1016/j.ssi.2015.03.039

    Abstract anzeigen

    7Li NMR relaxation has been used to study lithium-ion diffusion in layer-structured SnS2. Keeping the Li intercalation degree in LixSnS2 below x = 0.49, the Li ions preferentially occupy sites in the van der Waals gap between the SnS2 sheets. In contrast to conventional NMR spin-lattice relaxation (SLR) rate measurements in the laboratory frame of reference, which are sensitive to rather fast Li exchange processes, with the help of spin-locking SLR NMR slower Li motions were extracted from characteristic diffusion-induced rate peaks. The latter contain information on both Li+ activation energies Ea and Li ion jump rates τ− 1 characterizing the elementary steps of Li+ hopping. Our results point to two different diffusion processes (Ea(I) = 0.38 eV; Ea(II) = 0.28 eV), a slower and a faster one, observable directly after chemical Li insertion. Interestingly, the diffusion behaviour irreversibly changes when the sample has been exposed to temperatures as high as 573 K. Diffusion-induced NMR rates and corresponding line shapes are discussed with respect to an inhomogenous distribution of Li ions in SnS2, which seems to be present directly after Li intercalation.

    MobilNachhaltigTC Plattling MoMo

    Zeitschriftenartikel

    A. Dunst, Michael Sternad, V. Epp, M. Wilkening

    Fast Li+ Self-Diffusion in Amorphous Li–Si Electrochemically Prepared from Semiconductor Grade, Monocrystalline Silicon: Insights from Spin-Locking Nuclear Magnetic Relaxometry

    The Journal of Physical Chemistry C, vol. 119, no. 22, pp. 12183-12192

    DOI: 10.1021/acs.jpcc.5b02490

    Abstract anzeigen

    Silicon is one of the most promising anode materials for lithium-based rechargeable batteries. Provided the volume changes during Li uptake can be brought under control, Li ion diffusivity is expected to crucially determine the performance of such next-generation energy storage systems. Therefore, studying diffusion properties in e.g. amorphous Li–Si underpins applied research that is being directed toward the development of powerful storage devices. So far, only little information is available on Li+ self-diffusion in amorphous Si. Here, we used 7Li NMR spectroscopy to precisely quantify microscopic activation energies and Li jump rates in amorphous Li–Si which is primarily formed if monocrystalline Si is lithiated electrochemically. Surprisingly, our results reveal relatively fast Li ion diffusivity with low activation energies for localized Li+ motions being in agreement with results from theory. The average activation energy for long-range ion transport is as high as ca. 0.65 eV; jump rates turn out to be in the order of 2.5 × 105 s–1 at 246 K. Our results point to complex dynamics that is most likely governed by nonexponential motional correlation functions originating from a distribution of activation energies. The data obtained might help optimizing Li-based silicon batteries whose performance critically depend on fast Li ion transport.

    MobilNachhaltigTC Plattling MoMo

    Vortrag

    A. Dunst, Michael Sternad, V. Epp, M. Wilkening

    Li Self-Diffusion in Metastable Li15Si4 prepared from Monocrystalline Si - An Ex Situ 7Li NMR Relaxometry Study

    Poster presentation

    17th International Meeting on Lithium Batteries, Como, Italien

    MobilNachhaltigTC Plattling MoMo

    Vortrag

    A. Dunst, Michael Sternad, V. Epp, M. Wilkening

    Li Self-Diffusion in Amorphous Li/Si Prepared from Monocrystalline Si - A 7Li NMR Relaxometry Study

    Poster presentation

    65th Annual Metting of the International Society of Electrochemistry (ISE), Lausanne, Schweiz

    MobilNachhaltigTC Plattling MoMo

    Vortrag

    A. Dunst, Michael Sternad, V. Epp, M. Wilkening

    Lithium ion dynamics in amorphous Li-Si electrochemically prepared from semiconductor grade, monocrystalline silicon — An NMR Study

    Poster presentation

    Materials Day 2015, Graz, Österreich

    MobilNachhaltigTC Plattling MoMo

    Vortrag

    A. Dunst, Michael Sternad, V. Epp, M. Wilkening

    Fast Li self-diffusion in Li-Si Electrochemically Prepared from Semiconductor Grade, Monocrystalline Silicon

    15th European Conference on Solid State Chemistry (ECSSC), Wien, Österreich