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MM: Fachverband Metall- und Materialphysik
MM 56: Materials for Energy Storage and Conversion - Intercalation
MM 56.4: Vortrag
Donnerstag, 19. März 2020, 12:30–12:45, IFW D
A new hop: a DFTB model for Li diffusion in low-SOC graphite anodes. — •Chiara Panosetti1, Simon Annies1, Cristina Grosu1,2, Maria Voronenko1, and Christoph Scheurer1 — 1T. U. München — 2Forschungszentrum Jülich
Despite having been employed in consumer electronics for decades, Li-graphite anodes are not yet understood enough to e.g. upscale usage towards automotive applications. Many mechanisms involved in charging/discharging, ageing, and other key aspects, were never grasped in detail. Part of this difficulty is due to a structural complexity emerging particularly at low states of charge (SOC), which complicates both the interpretation of experiments and the computational modelling. From a computational standpoint, targeted system sizes compatible with the SOC range of interest are inaccessible to first-principles calculations, yet require first-principles treatment of key effects such as dispersion and long-range electrostatics. Density-Functional Tight Binding (DFTB), a semi-empirical approximation to DFT, offers a high-quality trade-off between accuracy and speed. With our recently developed parametrization [1], we are able for the first time to resolve the full Potential Energy Surface (PES) of Li motion in stage-I and stage-II LiC108 (SOC 5%). The PES contains information that enables us to implement, and hereby discuss, both kinetic Monte Carlo (kMC) models of Li-ion mobility in the graphite host, and free-energy sampling which ultimately yields the computed voltage profile of the anode.
[1] C. Panosetti et al., arXiv:1904.13351 (2019).