Influence of different state of charge on fire characteristics of single 32,650 lithium-ion battery in long-narrow confined space

The application prospect of lithium-ion battery (LIB) becomes broad with the development of society, and thermal runaway is a significant safety hazard of LIB. This paper studies the fire characteristics of a single 32,650 lithium-ion phosphate battery with different charges (100%, 75%, 50%, 25% and 0% SOC) heated by a constant heat source in a long-narrow confined space. The results showed that the mass loss rate and total burn time decreased with the increase of SOC, the combustion quality difference of the battery increased with the increase of SOC. The longitudinal smoke temperature drop rate in the long-narrow confined space was the highest, and the axial smoke temperature drop rate was approaching that of the transverse direction, which was about 0.14 times that of the longitudinal direction. A simplified model was derived to predict the mass loss of LIB with different SOC. The above conclusions provide theoretical support for quantitative assessment of the fire risk of the LIB in long-narrow confined space.