Investigation of gas diffusion behavior and detection of 86 Ah LiFePO4 batteries in energy storage systems during thermal runaway

With the widespread use of lithium iron phosphate (LFP) batteries in electrochemical energy storage (EES) systems, gas diffusion and early detection during thermal runaway (TR) are receiving increasing attention. In this work, the gas diffusion behavior and detection of a single 86 Ah LFP battery at two levels of the EES system are systematically investigated by a combination of experiment and simulation during TR. The TR experiment of a single 86 Ah LFP battery is carried out for the battery pack and it is evident that H2 diffusion is faster and earlier response than CO. The maximum concentrations of H2 and CO outside the battery pack are 1493 and 802 ppm, respectively. The gas diffusion behavior inside the battery energy storage container is simulated, and it is found that the maximum concentrations of H2 and CO are 618 and 412 ppm. Within 10 s after the safety venting, the gas diffusion behavior and detection are not affected by ventilation. However, during the later TR, the stable threshold of gas concentration under ventilation is much smaller than that without ventilation. The results can provide a theoretical guide in gas diffusion and detection, which is meaningful to the early warning and safe protection of EES systems.