Thermal runaway propagation (TRP) within lithium-ion batteries (LIBs) poses
critical barriers to the safe operation and large-scale application of
cell-to-chassis (CTC) batteries. Such events can lead to severe safety
incidents, including explosions and fires, in systems utilizing these batteries.
However, there is a lack of research on the thermal runaway model coupled with
vented gases at the CTC systems. In this study, a thermal runaway coupling model
for the battery pack system was established utilizing Star-CCM+ software,
allowing for the examination of thermal runaway propagation characteristics and
vented gas characteristics a within power battery systems based on the measured
parameters of battery thermal safety characteristic. The simulation results
indicated that once thermal runaway becomes uncontrollable, combustible flue
gases escape through the exhaust hole located on the side plate of the cell,
thereby facilitating heat transfer to adjacent cells. The primary components of
the gases emitted from lithium-ion batteries include CO2, CO,
H2, C2H2, CH4, O2,
among others. Notably, CO2 and CO constitute a significant proportion
of these emissions, accounting for 16.66% and 13.71%, respectively. This study
elucidates the dynamic mechanisms that underlie the propagation of thermal
runaway within a battery system, thereby providing suggestions for improving the
safety design of the CTC battery system and early warning in the CTC, and
contributing to trace the origin pattern of LIBs fire accident.