Tracing the Patterns of Thermal Runaway in Lfp Lithium-Ion Batteries

Abstract

The frequent occurrence of fire incidents in energy storage facilities and new energy vehicles has posed a significant challenge to the healthy and rapid development of the new energy industry. In-depth investigations into these incidents can uncover their root causes, providing a foundation for targeted safety optimizations in energy storage system design, thereby effectively reducing the risk of future occurrences. However, the disaster mechanisms of lithium battery fires are complex, and high temperatures, along with firefighting water sprays, often lead to the destruction of critical evidence. This creates significant challenges for the investigation and determination of the causes of battery fires. This study represents the first investigation into the chemical characteristics of lithium-ion battery thermal runaway traces under various thermal triggers and fire scene environments. Key aspects examined include valence changes of critical elements, crystal structure alterations, and both qualitative and quantitative features. Furthermore, the research establishes a mapping relationship between the characteristics of thermal runaway traces and their initiating factors. The results indicate that varying heating methods and fire scene environments have minimal impact on the crystal structure of the remnants. However, thermal runaway triggered by jet fire leads to a reduction in the Li 1s binding energy intensity within the debris. Additionally, both secondary heating from external fire sources and thermal runaway induced by solid heat transfer result in increased concentrations of Li and F, while the concentration of Fe decreases. Firefighting water sprays can lead to a reduction in the oxidation state of P within the debris, while prolonged immersion increases the oxidation state of Fe. Additionally, secondary heating from external fire sources reduces the binding energy intensities of O 1s and Li 1s. The findings of this study can be utilized to establish and expand a lithium-ion battery fire trace database, thereby enhancing investigative techniques for fires in energy storage stations and electric vehicles.

Keywords: Energy storage station, Lithium-ion battery, Thermal runaway, Accident investigation, Safety