Regensburg 2022 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 8: Materials for Storage and Conversion of Energy

MM 8.10: Vortrag

Montag, 5. September 2022, 18:15–18:30, H46

In-situ analysis of SEI formation and cycle behavior on Sn by combined QCM-CV — •Ke Wang and Guido Schmitz — Chair of Materials Physics, Institute for Materials Science, University of Stuttgart, Heisenbergstr. 3, 70569 Stuttgart, Germany

Sn (Tin) could in principle be a promising candidate for a lithium-ion battery anode since it offers larger capacity than commercially graphite. But, researchers are still confused about the capacity fade especially caused by the formation of solid electrolyte interface (SEI). Here, we perform an in-situ characterization to clarify the mechanisms of SEI formation. Cyclic voltammetry has been conducted in combination with a quartz crystal microbalance to measure the growth of the SEI. Beside the overall mass increase, evaluating the mass change per charge (MPE) even enables identification of the ab/desorbed species. In advanced analysis, we combine three different characteristics including mass spectra, real-time MPE and average MPE, for the different stages of the long-term SEI formation. Except the SEI layer formed in first cycle, the SEI is continuously affected by the formation of Li2O during lithiation and the oxidation of Sn during de-lithiation. In addition, the influence of the voltage window and the thickness of the electrodes on SEI formation are investigated. Remarkably, the SEI thickness reveals a linear relation to the electrode thickness which is linked to continuous cracking and major oxidization of Sn bulk. Particularly, the inorganic part of the SEI formed during lithiation in the specific voltage range of 0.36 - 0.27 V plays an important role on the microstructure of electrode and stabilizing the electrode.