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O: Fachverband Oberflächenphysik

O 20: Solid-Liquid Interfaces: Reactions and Electrochemistry - Experiment I

O 20.4: Vortrag

Montag, 20. März 2017, 17:15–17:30, WIL B321

Investigation of the Electrode-Electrolyte Interface in Lithium Ion Batteries Studied by Surface Science Methods — •Thomas Späth, Dirk Becker, Wolfram Jaegermann, and René Hausbrand — Institute of Material Science, Darmstadt University of Technology, Jovanka-Bontschits-Str. 2, 64287 Darmstadt

Reactions and Solid-Electrolyte Interface (SEI) formation between electrodes and electrolytes play a key role for performance and lifetime of batteries. For a better understanding of the reactivity of solvents with Li-ion battery electrode materials, we perform adsorption experiments on model electrodes. In these experiments we use High Resolution Electron Energy Loss Spectroscopy (HREELS) and Photoemission Spectroscopy (PES) to study vibrational modes and chemical composition at the surface. As both techniques offer complementary information, HREELS data can support the PES measurements.

In this contribution we present the results of our investigations of the electrode-electrolyte interface performing a stepwise adsorption of diethyl carbonate and dimetyl carbonate both on sputtered thin films of LiCoO₂ and lithiated silicon surfaces. We discuss the assignment of the different features in the pristine sprectra and present HREELS and PES spectra of the electrolyte adsorbed samples. For both techniques several new features can be observed, which are assigned to physically adsorbed species as well as chemisorbed or chemically reacted species. From this data we are able to conclude on the chemical reactions at the interfaces. This information allows us to obtain a deeper understanding of the SEI formation mechanisms in Lithium Ion Batteries.