Regensburg 2016 – wissenschaftliches Programm
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MM: Fachverband Metall- und Materialphysik
MM 31: Functional materials I: Supercapacitors and batteries I
MM 31.3: Vortrag
Mittwoch, 9. März 2016, 10:45–11:00, H53
NMR parameter computations and the local electronic structure in oxygen-deficient LTO — •Markus Schuderer, Karsten Reuter, and Christoph Scheurer — Theoretische Chemie, Technische Universität München, Garching
Spinel-structured lithium titanium oxide Li4Ti5O12 (LTO) is a promising zero-strain anode material for rechargeable lithium ion-batteries. Its relatively low electronic conductivity can be improved by introducing oxygen vacancies [1]. Experimental XPS [1] and EPR [2] results suggest the partial reduction of Ti ions. The description of the respective mixed-valent transition metal cation distribution is challenging for DFT methods. LTO’s inherent stoichiometric disorder and the spatial separation of vacancies from periodic images additionally requires large supercells. We have conducted systematic studies employing PBE, DFT+U, and hybrid functionals. The expected gap states are only found in hybrid calculations. Computed quadrupolar coupling constants for Li NMR spectroscopy are correlated with local geometric distortions and the electronic structure in the vicinity of O–vacancies, allowing for future combined theoretical and experimental NMR studies of the microscopic ion transfer pathways in this interesting material.
[1] J. Wolfenstine, U. Lee, J. L. Allen, J. Power Sources 2006, 154, 287.
[2] P. Jakes, J. Granwehr, H. Kungl, R.-A. Eichel, Z. Phys. Chem. 2015, 229, 1263.