Dresden 2020 – wissenschaftliches Programm
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CPP 55: Materials for Energy Storage and Conversion - Battery and Fuel Cell Materials (joint session MM/CPP)
CPP 55.3: Vortrag
Dienstag, 17. März 2020, 14:45–15:00, IFW D
Exploring defect structures in Li4Ti5O12 (LTO): A combined theoretical and experimental approach — •Yute Chan1, Cristina Grosu1,2, Karsten Reuter1, and Christoph Scheurer1 — 1TU München — 2IEK-9, FZ Jülich
Spinel Li4Ti5O12 (LTO) is a fascinating anode material for next-generation all-solid-state Li-ion batteries (ASSB). Its "zero strain" charge/discharge behavior promises high safety and long cycling lifetimes. Nonetheless, pristine, white LTO possesses poor ionic and electronic conductivity. The latter can be increased by tailoring the sintering protocol to produce oxygen vacancies, resulting in a performant, blue LTO material. Heretofore, the detailed structure and distribution of the vacancies are unknown. Thus, powerful analytic techniques are needed to identify the defect structure inside the material. Positron lifetime spectroscopy (PALS) stands out from other experimental methods by the ability to sensitively collect positron lifetimes that correlate to different material defects. Data measured at the Garching positron source indicates that the positron lifetimes for LTO bulk and surface are distinguishable. To invert these lifetimes and gain information for the respective regions, we construct a series of LTO bulk and slab models and calculate theoretical lifetimes using two different self-consistent schemes within the framework of two-component density functional theory. We will discuss the relationship between experimental and theoretical lifetimes of LTO bulk and surface.