In-operando Raman study of lithium plating on graphite electrodes of lithium ion batteries

• Published in: Electrochimica acta 2021-04, Vol.374, p.137487, Article 137487
• Main Authors: Cabañero, M.A., Hagen, M, Quiroga-González, E.
• Format: Article
• Language: English
• Subjects: Electrodes; Graphite; Graphite anode; In-operando; Li ion batteries; Lithium; Lithium plating; Lithium-ion batteries; Low currents; Plating; Raman; Raman spectroscopy; Rechargeable batteries; Spatial resolution; Spectrum analysis
• ISSN: 0013-4686; 1873-3859
• DOI: 10.1016/j.electacta.2020.137487

•Li2C2, always found in Raman spectra of metallic lithium, is a marker for plating.•This marker appeared right after the graphite bands vanished (full lithiation).•Li plating and chemical intercalation concurrently occurs during the CV step.•EC consumption in the electrolyte started after the onset of lithium plating. In-operando Raman spectroscopy with high spatial resolution (1 µm2) was employed to study the lithium deposition reaction on graphite electrodes. The 1850 cm−1 acetylide band, which is always found on lithium metal spectra, appeared right after reaching the full lithiation of graphite, when the G and D bands of graphite vanished. The band was observed during potestiostatic overcharge at high and low current rates and in a post-mortem analysis. The results suggest that during the constant voltage step, lithium is deposited and concurrently chemically intercalated into graphite. The second mechanism becomes the dominant after 30 min, when the current decreases. The evolution of the G and D bands of graphite and the lithium concentration in the electrolyte was also studied. The results suggest that EC is slowly consumed after the onset of lithium plating. This work demonstrates the possibility of studying locally the lithium plating onset and chemical intercalation on the graphite electrodes in real time. [Display omitted]