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Preparation, characterization and simulation studies of carbon nanotube electrodes for electrochemical energy storage

: Meißner, F.; Lorrmann, H.; Pastewka, L.; Endler, I.

Deutsche Gesellschaft für Chemisches Apparatewesen, Chemische Technik und Biotechnologie e.V. -DECHEMA-, Frankfurt/Main:
First International Conference on Materials for Energy 2010. Extended abstracts. Book B : July 4 - 8, 2010, Convention Center Karlsruhe, Germany
Frankfurt/Main: DECHEMA, 2010
ISBN: 978-3-89746-117-8
International Conference on Materials for Energy <1, 2010, Karlsruhe>
Conference Paper
Fraunhofer IKTS ()

Chemical Vapor Deposition (CVD) was employed to synthesize multiwalled carbon nanotubes (MWCNT) on different carrier materials for electrode applications. In the field of electrochemical energy storage it is essential to grow MWCNT on conducting substrates. For this reason titanium nitride (TiN) layers as well as a copper foil were used as substrates. The MWCNT grown on TiN layers show diameters of about 20 nm and lengths up to 13 µm. In the case of copper foil substrates a remarkably higher nanotube diameter of several tens of nanometers was found. First electrochemical characterization via cyclic voltammetry shows the potential of MWCNT as electrodes for energy storage applications. The CNT were measured in an organic carbonate electrolyte vs. a lithium counter electrode with various scan rates. Until now the preliminary investigations by cyclic voltammetry for electrodes consisting of aligned MWCNT on TiN showed a capacity of around 130 F g-1 in the range of 1 - 3 V vs. Li/Li+. In support of the experiments we construct a one dimensional Poisson-Nernst-Planck (PNP) continuum model that has been shown to yield agreement with corresponding molecular dynamics simulations to model ion transport into these types of electrodes. Our simulations show that first the ions accumulate at the tips of the tubes because the inner volume of the electrodes is initially field-free. A homogeneous charge distribution is then established through diffusion. The PNP model is used to compute cyclic voltammograms which show qualitative agreement with the experiments.