Thermal runaway and fire test of large cell battery shows high toxic emissions and dangers to firefighters. Seven tests were carried out on large (300 Ah, 0.54 kg) single cell LiFePO4 cathode lithium ion battery, as used in buses or for energy storage. The battery was externally heated (500 W) to simulate thermal runaway. This did not cause spontaneous ignition. In some tests, fire was manually ignited when safety valves opened (after c. 25 minutes) releasing high-temperature vapours and aerosols. Around ten minutes after ignition, temperatures reached c. 600°C. The ignited batteries released high levels of carbon monoxide, which would be lethally toxic in the case of a bus fire in a garage. The authors conclude that high ventilation rates are needed to ensure safety in case of electric vehicle fires and that emissions under heating mean that extinguished battery fires may reignite. They note that large single-cell LiFePO4 batteries may offer better safety than standard multi-cell lithium-ion configurations.
“Thermal runaway and fire behaviors of a 300 Ah lithium ion battery with LiFePO4 as cathode”, Renewable and Sustainable Energy Reviews 139 (2021) 110717, https://doi.org/10.1016/j.rser.2021.110717