Full-Scale Experimental Study on the Combustion Behavior of Lithium Ion Battery Pack Used for Electric Vehicle

The fire accidents caused by the thermal runaway of lithium-ion battery has extremely impeded the development of electric vehicles. With the purpose of evaluating the fire hazards of the electric vehicle, a full-scale thermal runaway test of the real lithium-ion battery pack is conducted in this work. The experimental process can be divided into three stages according to the combustion behavior. (1) Thermal runaway of the triggered module was induced and shows transient jet flame; (2) thermal runaway propagated between cells and further resulted in the constant repetition of ignition and re-ignition behavior; (3) the fire extinguish stage, in which the flame was suppressed and released a considerable amount of smoke. It is worth mentioning that it takes 22 s to evolve the triggered thermal runaway event to the worst case that the flame can spread throughout the whole cargo compartment. However, the water cannot directly act on the cells due to the shielding of the pack's cover in the fire extinguish stage, which greatly limits its cooling effect. The potential flame spread over electric vehicle is observed in this work, which can provide useful guidelines for the safety design of lithium-ion battery system.