Abstract:
The battery electric vehicle (BEV) is a promising technology for decarbonizing cities and
reducing reliance on fossil fuels. However, the main barrier to its widespread adoption is the issue
of safety. This study evaluates the risk of BEV occupants after exposure to hydrogen fluoride (HF)
gas and thermal stress caused by a fire accident. The HF data of exploded cylindrical, pouch, and
prismatic Li-ion batteries (LIBs) published in the literature were extrapolated to vehicle levels. Six
commercial off-the-shelf BEV models were used, with the assumption that their entire battery packs
would ignite at the same time. The risk was deemed acceptable if there was only one fatality per
million incidents of HF exposure per year. The maximum tolerable rectal temperature of 38ºC and
total water loss of 2500 g were used to evaluate thermal stress. The results show that, the higher the
number of cell in the pack, the higher is the HF concentration in the cabin. Moreover, the selected
BEV models exceeded the immediate dangerous to life or health (IDLH) level, making them prone
to risk the occupant. With the battery fire of 100ºC the rectal temperatures can be adverse after 7
minutes and unacceptable dehydration after 122 minutes, posing an acute thermal risk to occupants
when battery fire goes beyond 100ºC.
