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O: Fachverband Oberflächenphysik

O 45: Organic-Inorganic Hybrid Systems and Organic Films

O 45.23: Poster

Dienstag, 21. März 2017, 18:30–20:30, P1A

The Ionic Liquid|Graphite(0001) and Ionic Liquid|Li₄Ti₅O₁₂ (111) Interface as a Model for the Electrode|Electrolyte interface in Li-ion Batteries — •Jihyun Kim¹, Florian Buchner², Christiane Adler¹, Maral Bozorgchenani¹, Joachim Bansmann¹, and R. Jürgen Behm^1,2 — ¹Ulm University, Institute of Surface Chemistry and Catalysis, D-89069 Ulm, Germany — ²Helmholtz-Institute Ulm (HIU) Electrochemical Energy Storage, Helmholtzstr. 11, D-89081 Ulm, Germany

In this ultrahigh vacuum model study, we explore two anode processes which are highly important for the function of Li-ion batteries: (1) the reversible inter- and deintercalation of lithium (Li) and (2) the formation of the so-called electrode|electrolyte interface (EEI). Employing X-ray and UV photoelectron spectroscopy (XPS / UPS) and using well-defined anode surfaces such as graphite (0001) and Li₄Ti₅O₁₂ (111) (LTO) we found that vapor deposition of metallic Li on graphite (0001) at 80 K results in partially charged Li^{δ +} atoms, while for deposition at 300 K Li intercalates, forming Li_xC₆. Using Li₄Ti₅O₁₂ as substrate, Li diffuses into the bulk for deposition at 300 K as well, while for deposition at 80 K XPS reveals the formation of very small amounts of Ti³⁺. Evidently, under these conditions some of the Li remains near the surface, generating the Li-rich Li₇Ti₅O₁₂ phase, while the majority dissolves into the bulk. Finally, to mimic the EEI, we studied the temperature-dependent interaction of (sub-)monolayers of the ionic liquid [BMP][TFSA] with both graphite/lithiated graphite and the Li-poor/Li-rich LTO.