Regensburg 2010 – scientific programme

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MM: Fachverband Metall- und Materialphysik

MM 50: Topical Session Battery Materials II

MM 50.2: Talk

Thursday, March 25, 2010, 12:45–13:00, H6

Thermodynamics and electronic structure of intrinsic point defects in LiCoO₂ — •Melanie Gröting and Karsten Albe — Technische Universität Darmstadt, Institut für Materialwissenschaft, Petersenstr. 32, D-64342 Darmstadt

A key problem of rechargable battery devices is their degradation. Various processes including microstructural changes, redox and intercalation reactions with the electrolyte, and particularly point defects in the active material are believed to play an important role in the degradation process. Therefore a detailed understanding of these mechanisms is important for improving the materials properties. In this study we present density-functional theory calculations (DFT) of intrinsic point defects in LiCoO₂ using the supercell approach. Formation energies are calculated and the electronic structures and density of states are examined in order to compare them with XPS data. Also, the thermodynamic stability of Li_xCoO₂ with lithium contents x = 1.0, 0.5 and 0 is determined with respect to the competing metal oxides. We consider lithium and cobalt vacancies, as well as oxygen vacancies and interstitials. An important finding is that besides oxygen defects cobalt vacancies can dominate under certain conditions.