Regensburg 2016 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 73: Surface Dynamics: Reactions and Elementary Processes
O 73.4: Poster
Mittwoch, 9. März 2016, 18:15–20:30, Poster A
XPS Characterization of Sulphur Transformations during Operation of Li-S Batteries with Ultramicroporous Carbon-Sulphur Cathodes — •Thomas Diemant1, M. Helen2, M. Anji Reddy2, Maximilian Fichtner2,3, and R. Jürgen Behm1,2 — 1Institute of Surface Chemistry and Catalysis, Albert-Einstein-Allee 47, Ulm University, D-89081 Ulm — 2Helmholtz Institute Ulm, Helmholtzstr. 11, D-89081 Ulm — 3Institute of Nanotechnology, Karlsruhe Institute of Technology, P.O. Box 3640, D-76021 Karlsruhe
Lithium-sulphur (Li-S) batteries are discussed as potential successors of Li-ion cells. However, mainly due to the ’poly-sulphide shuttle’, Li-S batteries suffer at present from poor cycle life. One promising approach to overcome this problem is the use of microporous carbon confined sulphur, which eliminates the formation of higher order poly-sulphides. In this study, electrodes based on an ultramicroporous carbon-sulphur (UC-S) composite (46% S) were investigated. We studied the chemical state of sulphur in the UC-S cathodes at different stages of the lithiation/delithiation cycle by XPS analysis of the surface and subsurface region of the electrodes. Reasons for the capacity fading over cycling of the UC-S electrodes were elucidated. The structural properties were revealed using transmission electron microscopy (TEM). The results of XPS analysis together with the electrochemical performance measurements demonstrate the single step transformation of sulphur to Li2S2/Li2S and vice versa during the discharge/charge process. The UC-S electrodes used in this study exhibited a reversible capacity of 700 mAh/g at C/5 even after 100 cycles.