Regensburg 2000 – wissenschaftliches Programm
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O: Oberflächenphysik
O 32: Elektronische Struktur (V)
O 32.8: Vortrag
Donnerstag, 30. März 2000, 18:00–18:15, H37
In-Situ Photoelectron Spectroscopy Study of a Thin Film Cathode in an Operating Battery System — •Dino Tonti1, Christian Pettenkofer1, and Wolfram Jaegermann2 — 1Hahn-Meitner Institut, Glienickerstr. 100, 14109 Berlin — 2Technische Universität Darmstadt, Fachbereich Materialwissenschaft, Petersenstr. 23, 64287 Darmstadt
An intercalation battery system has been realised in UHV and was investigated by photoelectron spectroscopy and electrochemical methods at the same time. A TiS2 film was deposited on a Na+ conducting electrolyte, and a graphite layer was used on the backside of the plate as counterelectrode. By lowering the applied voltage between the TiS2 and the graphite Na intercalation is evidenced by Auger and core level signals. Due to the electron transfer to the conduction band an increase of the electron density at the Fermi level is clearly observed. The changes in the host’s valence band shift the Fermi level reference for the PES spectra, and as a result shifts to higher binding energies are observed in all levels. The Ti 2p peak broadens with a shoulder at the lower binding energy side, indicating a higher negative charge density localized on the Ti atoms.
In this way it is possible to relate the battery voltage with changes in structure, chemical composition, and electronic structure of the intercalation phase on a microscopic level. Moreover with this method it may be possible to extrapolate experimentally the variations of the electronic and ionic contributions to the battery voltage.