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Adsorption of ethylene carbonate on lithium cobalt oxide thin films: A synchrotron-based spectroscopic study of the surface chemistry

Fingerle, Mathias and Späth, Thomas and Schulz, Natalia and Hausbrand, René (2017):
Adsorption of ethylene carbonate on lithium cobalt oxide thin films: A synchrotron-based spectroscopic study of the surface chemistry.
In: Chemical Physics, Elsevier Science Publishing, pp. 19-24, (498-499), ISSN 03010104,
DOI: 10.1016/j.chemphys.2017.09.004,
[Online-Edition: https://doi.org/10.1016/j.chemphys.2017.09.004],
[Article]

Abstract

The surface chemistry of cathodic lithium cobalt oxide (LiCoO2) in contact with the Li-ion battery solvent ethylene carbonate (EC) was studied via synchrotron based soft X-ray photoelectron spectroscopy (SXPS). By stepwise in-situ adsorption of EC onto an rf-magnetron sputtered LiCoO2 thin film and consecutive recording of SXPS spectra, the chemical and electronic properties of the interface were determined. EC partially decomposes and forms a predominantly organic adlayer. Prolonged exposure results in the formation of a condensed EC layer, demonstrating that the decomposition layer has passivating properties. Lithium ions deintercalate from the electrode and are dissolved in the adsorbate phase, without forming a large amount of Li-containing reaction products, indicating that electrolyte reduction remains limited. Due to a large offset between the LiCoO2 valence band and the EC HOMO, oxidation of EC molecules is unlikely, and should require energy level shifts due to interaction or double layer effects for real systems.

Item Type: Article
Erschienen: 2017
Creators: Fingerle, Mathias and Späth, Thomas and Schulz, Natalia and Hausbrand, René
Title: Adsorption of ethylene carbonate on lithium cobalt oxide thin films: A synchrotron-based spectroscopic study of the surface chemistry
Language: English
Abstract:

The surface chemistry of cathodic lithium cobalt oxide (LiCoO2) in contact with the Li-ion battery solvent ethylene carbonate (EC) was studied via synchrotron based soft X-ray photoelectron spectroscopy (SXPS). By stepwise in-situ adsorption of EC onto an rf-magnetron sputtered LiCoO2 thin film and consecutive recording of SXPS spectra, the chemical and electronic properties of the interface were determined. EC partially decomposes and forms a predominantly organic adlayer. Prolonged exposure results in the formation of a condensed EC layer, demonstrating that the decomposition layer has passivating properties. Lithium ions deintercalate from the electrode and are dissolved in the adsorbate phase, without forming a large amount of Li-containing reaction products, indicating that electrolyte reduction remains limited. Due to a large offset between the LiCoO2 valence band and the EC HOMO, oxidation of EC molecules is unlikely, and should require energy level shifts due to interaction or double layer effects for real systems.

Journal or Publication Title: Chemical Physics
Number: 498-499
Publisher: Elsevier Science Publishing
Uncontrolled Keywords: XPS,LiCoO2,Ethylene carbonate,SEI, Li-ion battery, Ionic interface
Divisions: 11 Department of Materials and Earth Sciences
11 Department of Materials and Earth Sciences > Material Science
11 Department of Materials and Earth Sciences > Material Science > Surface Science
Date Deposited: 27 Sep 2017 08:08
DOI: 10.1016/j.chemphys.2017.09.004
Official URL: https://doi.org/10.1016/j.chemphys.2017.09.004
Funders: We thank HZB for the allocation of synchrotron radiation beamtime and for financial support., This project was funded by the DFG (HA 6128/1-1).
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