Berlin 2024 – wissenschaftliches Programm
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KFM: Fachverband Kristalline Festkörper und deren Mikrostruktur
KFM 24: Focus Session: Battery Materials – Ion Transport, Impurity Effects and Modelling (joint session KFM/MM)
KFM 24.8: Vortrag
Donnerstag, 21. März 2024, 12:15–12:35, EMH 225
Elucidating the Silicon Voltage Hysteresis by Mechanical Coupling of Anode Particles and SEI — •Lukas Köbbing1,2, Arnulf Latz1,2,3, and Birger Horstmann1,2,3 — 1German Aerospace Center (DLR), Ulm, Germany — 2Helmholtz Institute Ulm (HIU), Ulm, Germany — 3Ulm University, Ulm, Germany
Silicon promises to be a superior next-generation anode material. However, a major challenge of silicon anodes is the significant voltage hysteresis reducing efficiency and leading to detrimental heat generation. Additionally, the hysteresis hinders precise state-of-charge estimation. Our recent research identifies the chemo-mechanical coupling of silicon and the Solid-Electrolyte Interphase (SEI) as the reason for the substantial voltage hysteresis. The SEI is a thin passivating film that grows on negative electrode particles due to electrolyte decomposition [1]. For silicon particles, volume changes lead to significant strains and plastic deformation within the SEI [2]. As anode particle and SEI are mechanically coupled, the stress generated inside the SEI impacts the stress inside the anode, affecting its potential. Our chemo-mechanical model reproduces the observed open-circuit voltage hysteresis [3]. Furthermore, our visco-elastoplastic SEI model reproduces the voltage difference between slow cycling and the relaxed voltage. This detailed physical understanding can improve the performance of silicon anodes. [1] L. Köbbing et al. J. Power Sources 2023, DOI: 10.1016/j.jpowsour.2023.232651. [2] L. Kolzenberg et al. Batter. Supercaps 2022, 5, DOI: 10.1002/batt.202100216. [3] L. Köbbing et al. Adv. Funct. Mater. 2023, DOI: 10.1002/adfm.202308818.
Keywords: lithium-ion batteries; silicon anode; voltage hysteresis; solid-electrolyte interphase (SEI); mechanical model