This study investigates the thermal structural behavior of lithiated graphite anodes in Li-ion batteries, focusing on the thermal stability and degradation mechanisms. The research combines ex situ high-resolution X-ray and neutron diffraction with electrochemical data to analyze the structural evolution of lithiated graphite at various states-of-charge (SOCs) and temperatures. Key findings include: 1. **Low-Temperature Behavior**: At low temperatures, no significant degradation of lithiated graphite was observed, except for minor changes in reflection intensities and the appearance of additional reflections from frozen electrolyte components. The electrolyte reflections remained stable up to 325 K, suggesting the presence of dried-out electrolyte residues. 2. **High-Temperature Behavior**: At high temperatures, a non-reversible decomposition of lithiated graphite occurred, starting around 350 K. This decomposition is kinetically controlled by temperature, leading to delithiation and the formation of novel phases such as LiF and Li₂O. Calorimetric measurements confirmed the exothermic nature of these reactions, with the onset of degradation at 374 K and a maximum temperature of 525 K. 3. **Morphological Characterization**: Post-mortem scanning electron microscopy (SEM) revealed the impact of thermal degradation and electrochemical cycling on the lithiated electrode material. The surface of the graphite flakes was passivated by reaction products, and the amount of oxygen-rich products increased with higher SOC. EDX measurements confirmed the presence of silicon in the anode, possibly in an amorphous form. 4. **Conclusion**: The study highlights the complex thermal stability of lithiated graphite anodes in real-life batteries, which is critical for fast charging and discharging applications. The findings suggest that optimizing the high-temperature stability of binders and electrolytes may be necessary to mitigate thermal runaway risks and improve battery performance. This research provides valuable insights into the thermal behavior of lithiated graphite anodes, contributing to the understanding of battery degradation mechanisms and the development of more robust battery materials.This study investigates the thermal structural behavior of lithiated graphite anodes in Li-ion batteries, focusing on the thermal stability and degradation mechanisms. The research combines ex situ high-resolution X-ray and neutron diffraction with electrochemical data to analyze the structural evolution of lithiated graphite at various states-of-charge (SOCs) and temperatures. Key findings include: 1. **Low-Temperature Behavior**: At low temperatures, no significant degradation of lithiated graphite was observed, except for minor changes in reflection intensities and the appearance of additional reflections from frozen electrolyte components. The electrolyte reflections remained stable up to 325 K, suggesting the presence of dried-out electrolyte residues. 2. **High-Temperature Behavior**: At high temperatures, a non-reversible decomposition of lithiated graphite occurred, starting around 350 K. This decomposition is kinetically controlled by temperature, leading to delithiation and the formation of novel phases such as LiF and Li₂O. Calorimetric measurements confirmed the exothermic nature of these reactions, with the onset of degradation at 374 K and a maximum temperature of 525 K. 3. **Morphological Characterization**: Post-mortem scanning electron microscopy (SEM) revealed the impact of thermal degradation and electrochemical cycling on the lithiated electrode material. The surface of the graphite flakes was passivated by reaction products, and the amount of oxygen-rich products increased with higher SOC. EDX measurements confirmed the presence of silicon in the anode, possibly in an amorphous form. 4. **Conclusion**: The study highlights the complex thermal stability of lithiated graphite anodes in real-life batteries, which is critical for fast charging and discharging applications. The findings suggest that optimizing the high-temperature stability of binders and electrolytes may be necessary to mitigate thermal runaway risks and improve battery performance. This research provides valuable insights into the thermal behavior of lithiated graphite anodes, contributing to the understanding of battery degradation mechanisms and the development of more robust battery materials.