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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 55: Materials for Energy Storage and Conversion - Battery and Fuel Cell Materials (joint session MM/CPP)
CPP 55.2: Vortrag
Dienstag, 17. März 2020, 14:30–14:45, IFW D
Polaron Hopping Mechanism as a source for electronic conductivity in Li4Ti5O12 (LTO) Batteries — •Matthias Kick1, Cristina Grosu1,2, Markus Schuderer1, Christoph Scheurer1, and Harald Oberhofer1 — 1Technische Universität München — 2Forschungszentrum Jülich
State of the art lithium ion batteries rely on graphite as anode material due its remarkable lithium-intercalation properties. However due to the low intercalation potential of graphite, Li dendrite growth can occur during rapid charge processes, rendering a potential risk of having short-circuits in a battery cell. In addition, the large volume change during (dis)charging the battery results in unfavorable strain damaging the anode. Lithium titanium oxide Li4Ti5O12 (LTO) shows the potential of being an excellent alternative to graphite anodes, as its volume stays stable during charge cycles and its high intercalation potential prevents Li dendrites to form. Unfortunately, the low conductivity of LTO still limits its use. To improve on this drawback, an elegant way is to introduce oxygen vacancies resulting in formation of Ti3+ centers. As a result, this blue colored LTO shows a lowering in its electronic resistance with improved electronic conductivity. By performing Hubbard corrected density functional theory (DFT+U) calculations we are able to show that in fact polaron formation and a possible polaron hopping mechanism can play a significant role in the experimental observed improved conductivities. Morevover we are able to gauge polaronic charge mobility by explicitly calculating polaron hopping barriers.