Regensburg 2022 – scientific programme

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MM: Fachverband Metall- und Materialphysik

MM 18: Poster Session 2

MM 18.20: Poster

Tuesday, September 6, 2022, 17:30–20:00, P2

Quantitative investigation of reversible Li2O formation on Germanium battery anodes — •Ke Wang and Guido Schmitz — Chair of Materials Physics, Institute for Materials Science, University of Stuttgart, Heisenbergstr. 3, 70569 Stuttgart, Germany

Lithium-ion batteries (LIB) serves as efficient energy storage devices in many aspects of our life. Anodes belonging to the Group IV (Si, Ge and Sn) are promising candidates to replace commercially applied graphite (372 mAh g-1) owing to their high theoretical capacity (3850 mAh g-1 for Si, 1570 mAh g-1 for Ge, and 990 mAh g-1 for Sn). But, the respective mechanisms of Li storage and the formation of solid electrolyte interface (SEI) are still not clearly. In this work, cyclic voltammetry has been conducted in combination with a quartz crystal microbalance to measure the SEI mass, and the amount of eventual reversibly processed species. Similar to Si and Sn, also with Ge anodes, the QCM mass spectroscopy identifies Li2O as a reversibly processed species that contributes a significant part to the electrochemical capacity. The amount of reversibly stored Li2O decreases weakly with increasing cycling rate, but increases significantly with the thickness of the Ge anodes. Interestingly, the amount of Li2O decreases if pronounced anode cracking appears, which is probably attributed to the fact that the fracture introduces short circuit transport paths deep into the volume of the Ge which accelerates lithiation. Thermodynamically, Li*2O should form before Li is inserted. But in the experiment simultaneously formation of Li*2O and LixSny is observed on Sn, probably attributed to lateral heterogeneity introduced by surface roughness.