Operando X-ray Diffraction of Graphite (De-)lithiation at Various Temperatures

Kurzfassung

Operando X-ray diffraction (XRD) is a powerful tool to investigate phase changes of battery materials during cycling. Graphite, the state-of-the-art anode material, undergoes several phase changes during lithiation and delithiation. This phase evolution does not only depend on the operating temperature but also on the current direction and rate. Low temperature diffraction studies of graphite have been conducted but a detailed analysis by Rietveld refinement is missing. To shed light on the temperature and current dependency of graphite, we performed an operando XRD study at 0 °C, 25 °C and 43 °C at two different current rates accompanied by a detailed Rietveld refinement analysis.5 The study shows that at 0 °C, the phase evolution is altered compared to room temperature leading to several co-existing phases during delithiation even at low current rates. Overall, differences between lithiation and delithiation are more pronounced at 0 °C compared to higher temperatures. Additionally, the temperature influence on the formation of stage 2L could be unravelled.