Berlin 2015 – scientific programme
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MM: Fachverband Metall- und Materialphysik
MM 10: Functional materials II: Battery Materials
MM 10.5: Talk
Monday, March 16, 2015, 12:45–13:00, TC 010
Separation of surface and bulk stress in a model lithium alloy electrode reveals grain boundary alloying at high electric potentials vs. Li/Li+. — •Tobias Kitzler1, Jürgen Markmann1,2, Emad Maawad3, Daniel Többens4, and Jörg Weißmüller1,2 — 1Helmholtz-Zentrum Geesthacht, Department of Materials Reserch, Materials Mechanics — 2Hamburg University of Technilogy, Department of Materials Physics and Materials Technology — 3Helmholtz-Zentrum Geesthacht, Department of Materials Reserch, Materials Physics — 4Helmholtz-Zentrum Berlin, Department of crystallography
We present the results of a combined study using the potential strain coupling parameter and microstructural characterisation to separate surface and bulk contributions to the stress in gold thin film electrodes during electrochemical cycling in an organic lithium electrolyte.
The results were used to show, that grain boundary alloying is an important mechanism which appears long before intermetallic alloys appear, and that it induces a stress on a film electrode which can easily be mistaken as a surface stress. This is especially important, since the effect is in the same order of magnitude (apparent surface stress: -2.9 N/m) as the actual surface stress. Furthermore the separation allowed estimating the surface stress resulting from underpotential deposition of lithium on the gold surface of roughly -2.6 N/m, which is good agreement with DFT results of -2.8 N/m calculated by Tavessol et. al.