Abstract: Lithium iron phosphate batteries under abusive conditions will experience thermal runaway, generating a large number of flammable and toxic gases, easy to cause fire or even explosion accidents, which has become a problem restricting the further development of lithium iron phosphate battery energy storage. In view of this, this paper built an experimental platform consistent with the real energy storage cabin. Lithium iron phosphate battery was taken as the experimental object to carry out the thermal runaway gas micro-leakage experiment at the level of battery cell, module and battery cluster. Spectral imaging device, combustible gas detector and visible light camera were used for the whole gas monitoring. The experimental results show that: the position of the gas detector has a great influence on the early warning time. The detector closer to the experimental position responds first, the peak time is the earliest, and the peak value is the largest. The H2 response speed of the detector at different positions is faster than that of CH4 and CO, so H2 can be used as the first-level early warning. In different levels of gas micro-leakage experiments, due to the spectral imaging device can be directly detected on the leakage location, so the CH4 and CO spectral imaging early warning time are earlier than the H2, CH4 and CO detector. The early warning time of CH4 spectral imaging is earlier than that of CO imaging, because the battery generates electrolyte vapor earlier than the release time of CH4 and CO in the early stage of the experiment, and CH4 imaging is more sensitive to volatile organic compounds (VOC). Spectral imaging detection earlier than the battery thermal runaway is greatly affected by obstacles, and can be combined with other detection methods for early warning and fault location.

Key words: lithium iron phosphate battery, thermal runaway, energy storage chamber, spectral imaging, gas detection