Early Detection of Li-Ion Battery Thermal Runaway Using Commercial Diagnostic Technologies

The exponential growth in electric vehicle adoption powered by Li-ion batteries necessitates a thorough understanding of the state of stability (SoS) of the cells within battery packs, as this knowledge is crucial for preventing catastrophic failures that could lead to injury or loss of life. This study explores the use of rapid electrochemical impedance spectroscopy (EIS) and gas sensing technology as diagnostics for monitoring cells and packs for failure markers indicative of SoS. The methodology involves experimental assessments of single cells and battery packs under thermal and electrical abuse conditions, whereby key changes in their performance are analyzed. Results demonstrate that rapid EIS provides longer warning times compared to volatile organic compound (VOC) sensors and hydrogen (H2) sensors, indicating its effectiveness in early detection of impending failures. However, the reliability of using EIS to identify impedance changes diminishes with increasing pack complexity, highlighting the influence of packaging and engineering intricacies on monitoring efforts. These findings contribute empirical evidence to the ongoing development of safety protocols for Li-ion batteries in electric vehicles.