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MM: Fachverband Metall- und Materialphysik
MM 52: Materials for Energy Storage and Conversion - Ion Diffusion
MM 52.2: Vortrag
Donnerstag, 19. März 2020, 10:30–10:45, IFW D
Atomistic analysis of migration properties of Li in Li1+xAlxTi2−x(PO4)3 (LATP) solid electrolytes — Daniel Pfalzgraf1,2, •Daniel Mutter1, Daniel F. Urban1, and Christian Elsässer1,2 — 1Fraunhofer IWM, Freiburg, Germany — 2University of Freiburg, Germany
LATP [Li1+xAlxTi2−x(PO4)3] is considered as one of the most promising ceramic materials to replace hazardous liquid electrolytes in all-solid state Li-ion batteries. This is mainly because of a three-dimensional structural diffusion network enabling fast transport of Li ions through well-defined channels. It has been observed that an Al ratio of x=0.3 leads to the best performing compounds in terms of ionic conductivity. But a comprehensive understanding of this phenomenon is still missing. In this study, atomistic simulations based on density functional theory were performed to analyze the influence of Al substitution on Ti lattice sites on the migration behavior of Li. In LATP, the migration is dominated by a correlated mechanism involving three Li ions. In a systematic manner it is explored how different combinations of Al and Ti around the migration path change the energies of initial and final configurations as well as the energy barrier. "Al-like" and "Ti-like" behaviors can be identified, and the influence of the change of the LATP unit-cell volume with Al concentration is analyzed. We discuss the advancements and limitations of our approach in finding building blocks to describe quantitatively the Li migration in various arrangements of Al and Ti in LATP.