Hydrogen gas diffusion behavior under fault conditions and detector installation optimization of electric vehicles

The thermal runaway of lithium-ion batteries presents a significant threat to electric vehicles by elevating the risk of fires or explosions. Safety warnings based on special gases such as H2 and CO are crucial to avoid thermal runaway. However, few studies or applications regarding gas warnings in electric vehicles have been reported. In this study, H2 detection experiments were performed in a real electric vehicle battery pack, and the H2 diffusion behavior was studied. The results showed that H2 can effectively warn about battery faults. In damaged batteries, H2 may be released from the micro-cracks in the battery or the vent. While H2 was detected and the power supply was cut off, the cell surface temperature tended to decrease and thermal runaway did not occur. The installation of the detector affects the detection time. Thus, H2 diffusion simulations starting from different locations were performed, and the installation location was optimized. The results indicated that setting two detectors was optimal, and the optimized detection time (from release to detection of H2) was 60 s shorter than that before optimization. The experimental and simulation results provide an effective msethod for the early warning of thermal runaway and the installation of gas detectors in electric vehicles.