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Adsorption of Diethyl Carbonate on LiCoO2 Thin Films: Formation of the Electrochemical Interface

Becker, Dirk and Cherkashinin, Gennady and Hausbrand, René and Jaegermann, Wolfram (2014):
Adsorption of Diethyl Carbonate on LiCoO2 Thin Films: Formation of the Electrochemical Interface.
In: The Journal of Physical Chemistry C, ACS Publications, pp. 962-967, 118, (2), ISSN 1932-7447,
[Online-Edition: http://dx.doi.org/10.1021/Jp405714x],
[Article]

Abstract

Despite numerous efforts to elucidate interface-related phenomena of Li ion battery cathodes, the exact nature of cathode/electrolyte interfaces is still not fully resolved. Key factors for the properties of semiconducting ionic electrodes are band bending and energy level alignment at the interface, which have not been given much attention in the past. In this contribution, we investigate the formation of the electrochemical interface for a LiCoO2 electrode in contact with a solvent adsorbate phase by a surface science approach. Diethyl carbonate (DEC) was adsorbed stepwise onto a LiCoO2 thin film electrode and the electrode surface analyzed with X-ray photoelectron spectroscopy (XPS) after each adsorption step. Adsorption results in the formation of a charged layer in the electrode, which we attribute to the transfer of lithium ions from the electrode to the adsorbed phase. The offset between the LiCoO2 valence band and HOMO of the adsorbed DEC is large (4 eV) under the experimental conditions, which renders solvent oxidation unlikely.

Item Type: Article
Erschienen: 2014
Creators: Becker, Dirk and Cherkashinin, Gennady and Hausbrand, René and Jaegermann, Wolfram
Title: Adsorption of Diethyl Carbonate on LiCoO2 Thin Films: Formation of the Electrochemical Interface
Language: English
Abstract:

Despite numerous efforts to elucidate interface-related phenomena of Li ion battery cathodes, the exact nature of cathode/electrolyte interfaces is still not fully resolved. Key factors for the properties of semiconducting ionic electrodes are band bending and energy level alignment at the interface, which have not been given much attention in the past. In this contribution, we investigate the formation of the electrochemical interface for a LiCoO2 electrode in contact with a solvent adsorbate phase by a surface science approach. Diethyl carbonate (DEC) was adsorbed stepwise onto a LiCoO2 thin film electrode and the electrode surface analyzed with X-ray photoelectron spectroscopy (XPS) after each adsorption step. Adsorption results in the formation of a charged layer in the electrode, which we attribute to the transfer of lithium ions from the electrode to the adsorbed phase. The offset between the LiCoO2 valence band and HOMO of the adsorbed DEC is large (4 eV) under the experimental conditions, which renders solvent oxidation unlikely.

Journal or Publication Title: The Journal of Physical Chemistry C
Volume: 118
Number: 2
Publisher: ACS Publications
Divisions: 11 Department of Materials and Earth Sciences > Material Science > Surface Science
11 Department of Materials and Earth Sciences > Material Science
11 Department of Materials and Earth Sciences
Date Deposited: 27 Feb 2015 09:57
Official URL: http://dx.doi.org/10.1021/Jp405714x
Identification Number: doi:10.1021/Jp405714x
Funders: The authors wish to acknowledge the financial support by the Deutsche Forschungsgemeinschaft (DFG) and the Federal Ministry of Education and Research (BMBF, Support Code 03KP801).
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