Experimental investigation on the venting gas of cell-to-pack lithium-ion battery module during thermal runaway

As the latest technology to promote the transformation of the new energy automobile industry, cell-to-pack (CTP) batteries have attracted unprecedented attention. However, there is a lack of research on the vented gases at the module level. In this paper, the thermal runaway propagation (TRP) behavior and vented gas characteristics of large modules of cell-to-pack batteries in closed space are studied experimentally. Results indicated that the total quantity of vented gas from module during thermal runaway (TR) process was 31.01 mol. The main components of vented gas are H2, CO2, CO, C2H4, and CH4. Of these, H2, CO2 and CO accounted for 32.85 %, 28.00 % and 25.25 % respectively. In addition, the calculated explosion limit of vented gases was 6.27 %–54.14 %. Therefore, the vented gas is prone to explosion, causing serious accidents. Compared with the open space system, the TRP temperature of the battery module in the closed nitrogen space system was higher and the mass loss was smaller. This study can provide reference for the prevention of TRP in large battery modules, and for evaluating the fire hazard of powered vehicles. •The vented gas during thermal runaway of CTP battery module is discussed.•The thermal runaway propagation characteristics in open space air system and under nitrogen environment in a closed space are compared.•The explosion hazard of vented gas is analyzed.•Results contribute towards reducing the hazard of CTP batteries during thermal runaway propagation.