Abstract: In order to revealed the cylindrical lithium - ion battery fire behaviors and smoke characteristics under different thermal runaway process, the thermal runaway tests of 18650 lithium batteries were conducted, through the combustion chamber and 9705 systems. The parameters of thermal runaway behaviors, smoke composition and density were obtained, during the thermal runaway process of gases ejection, jet combustion and explosion. The results showed that, the concentration of hydrocarbon, CO and other flammable gases were higher in the process of jet combustion. The higher fire temperature and explosion hazard were obtained under the thermal runaway way of explosion - combustion, but the smoke density and CO, CnHx gas content was lower. Burst is the most severe and dangerous.

Key words: lithium - ion battery safety, thermal runaway, explosion and combustion behaviors;smoke composition, heat release rate