6
with air. Carbon dioxide is inert and displaces other gasses
to impede combustion.
Where battery enclosure internal volume restrictions
may prevent adequate free space, thermal runaway cascade
prevention and venting with properly designed and main-
tained flame arrestors are potential mitigation strategies for
excessive overpressures [10]. Limiting thermal runaway to
a small portion of a battery can reduce the amount of gas-
generated pressure. Properly designed and maintained flame
arrestors may provide pressure relief of ignitions within
sealed enclosures while preventing ignition of a surrounding
Figure 11. Escaping gasses etched a path through soot that
accumulated in the cover joint
Figure 12. Thermal runaway pressure deformed the XP
enclosure bottom plate beyond allowable limits
Figure 13. XP enclosure pressure and pressure rise rate
compared to sealed enclosure pressures and pressure rise
rates
Figure 14. Time traces of carbon monoxide and carbon
dioxide sampled several meters downwind from the battery
thermal runaway