SKM 2023 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 23: Poster II

MM 23.16: Poster

Dienstag, 28. März 2023, 18:15–20:00, P2/OG1+2

Optical Modulation and Phase Distribution in LiCoO2 upon Li-ion De/Intercalation — Sanaz Banifarsi, •Yug Joshi, Robert Lawitzki, Gábor Csiszár, and Guido Schmitz — Chair of Materials Physics, Institute of Materials Science, University of Stuttgart, 70569 Stuttgart, Germany

The optical modulation of sputter deposited thin-films of LiCoO2 upon de-/lithiation is probed in reflectance geometry. The thin-films of LiCoO2 (LCO) are sputter-coated using ion-beam sputtering, onto mirror-like platinum current collectors. A reversible electrochemical and electrochromic behavior is obtained from the in-operando electrochemical and optical measurements. The optical constants (using ex-situ optical spectroscopy) are obtained by modelling the obtained spectra using Clausius-Mossotti relation. The model parameters reveal a dominant resonant wavelength at 646 nm for the fully intercalated LCO. For the delithiated state, Li0.5CoO2, a much broader and more intense absorption peak is obtained. This broad and intense peak is correlated to the conducting nature of the delithiated state. The obtained complex refractive index (CRI) are justified by prior reported calculations of the density of states. With the evolving CRI, the variation in the imaginary and real part of the dielectric constant is understood by a layered phase propagation. This is due to (i) the faster diffusion between the layers of CoO6 octahedra of the layered structured LCO and, (ii) the alignment of these octahedral planes almost perpendicular to surface of the electrode as a result of the identified growth texture (due to the deposition and the subsequent annealing).