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Sulfur X-ray absorption fine structure in porous Li-S cathode films measured under argon atmospheric conditions

Title data

Müller, Matthias ; Choudhury, Soumyadip ; Gruber, Katharina ; Cruz, Valene B. ; Fuchsbichler, Bernd ; Jacob, Timo ; Koller, Stefan ; Stamm, Manfred ; Ionov, Leonid ; Beckhoff, Burkhard:
Sulfur X-ray absorption fine structure in porous Li-S cathode films measured under argon atmospheric conditions.
In: Spectrochimica Acta Part B: Atomic Spectroscopy. Vol. 94-95 (April 2014) . - pp. 22-26.
ISSN 0584-8547
DOI: https://doi.org/10.1016/j.sab.2014.03.001

Abstract in another language

In this paper we present the first results for the characterization of highly porous cathode materials with pore sizes below 1 mu m for Lithium Sulfur (Li-S) batteries by Near Edge X-ray Absorption Fine Structure (NEXAFS) spectroscopy. A novel cathode material of porous carbon films fabricated with colloidal array templates has been investigated. In addition, an electrochemical characterization has been performed aiming on an improved correlation of physical and chemical parameters with the electrochemical performance. The performed NEXAFS measurements of cathode materials allowed for a chemical speciation of the sulfur content inside the cathode material. The aim of the presented investigation was to evaluate the potential of the NEXAFS technique to characterize sulfur in novel battery material. The long term goal for the characterization of the battery materials is the sensitive identification of undesired side reactions, such as the polysulfide shuttle, which takes place during charging and discharging of the battery. The main drawback associated with the investigation of these materials is the fact that NEXAFS measurements can usually only be performed ex situ due to the limited in situ instrumentation being available. For Li-S batteries this problem is more pronounced because of the low photon energies needed to study the sulfur K absorption edge at 2472 eV. We employed 1 mu m thick Si3N4 windows to construct sealed argon cells for NEXAFS measurements under ultra high vacuum (UHV) conditions as a first step towards in situ measurements. The cells keep the sample under argon atmosphere at any time and the X-ray beam passes mainly through vacuum which enables the detection of the low energy X-ray emission of sulfur. Using these argon cells we found indications for the presence of lithium polysulfides in the cathode films whereas the correlations to the offline electrochemical results remain somewhat ambiguous. As a consequence of these findings one may state that measurements for battery material characterization are preferably to be performed completely in situ with the electrochemical measurements taking place simultaneously in order to obtain clear and unambiguous results.

Further data

Item Type: Article in a journal
Refereed: Yes
Institutions of the University: Faculties > Faculty of Engineering Science > Professur Biofabrikation > Professur Biofabrikation - Univ.-Prof. Dr. Leonid Ionov
Faculties
Faculties > Faculty of Engineering Science
Faculties > Faculty of Engineering Science > Professur Biofabrikation
Result of work at the UBT: Yes
DDC Subjects: 500 Science > 540 Chemistry
Date Deposited: 23 Jun 2017 10:56
Last Modified: 16 Apr 2018 12:21
URI: https://eref.uni-bayreuth.de/id/eprint/37964