SKM 2023 – wissenschaftliches Programm
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MM: Fachverband Metall- und Materialphysik
MM 16: Energy Conversion
MM 16.2: Vortrag
Dienstag, 28. März 2023, 10:30–10:45, SCH A 215
Revisiting the storage capacity limit of graphite battery anodes: spontaneous lithium overintercalation at ambient pressure — Cristina Grosu1,2, •Chiara Panosetti1, Steffen Merz2, Peter Jakes2, Sebastian Matera1, Rüdiger-A. Eichel2, Josef Granwehr2, and Christoph Scheurer1,2 — 1Fritz-Haber-Institut der MPG, Berlin, Germany — 2IEK-9, FZ Jülich, Germany
The market quest for fast-charging, long-lasting, safe batteries drives the exploration of new energy storage materials, but also promotes fundamental studies of those already widely used–primarily graphite anodes for Li-ion batteries. We focus on the upper intercalation limit in the morphologically quasi-ideal highly oriented pyrolytic graphite, with a LiC6 stoichiometry corresponding to 100% state of charge. A sample prepared by immersion in liquid Li at ambient pressure, investigated by 7Li nuclear magnetic resonance (NMR), shows unexpected signatures of superdense intercalation compounds, LiC6−x. These were ruled out for decades, as the highest geometrically accessible composition, LiC2, can only be prepared under high pressure. We monitored the sample upon calendaric aging and employed DFT calculations to rationalise NMR findings. Computed free energies reveal that non-negligible overintercalation proceeds spontaneously beyond the currently accepted capacity limit. Challenging the widespread notion that any additional intercalation beyond LiC6 is not possible under ambient conditions, we highlight the implications on performance-crucial phenomena and critically discuss possible quantitative characterization routes[1].
[1] C. Grosu et al., arXiv:2107.11137 (2021)