Meaning
Direct exposure to concentrated, pressurized streams of burning gas expelled by a failing battery cell tests the endurance of neighboring structural barriers. When a lithium-ion cell experiences thermal runaway, it often vents a high-velocity mixture of flammable gases and hot particles that ignites immediately. This jet flame impingement can melt thin metal covers and burn through plastic battery housings within seconds.
It presents the most severe thermal challenge to pack containment design.
Destructive Dynamic
The pressure within a failing cell builds until the safety vent or cap ruptures, creating a torch-like flame directed at a single point. This localized heat flux is far higher than the radiant heat of a general pool fire. Materials subjected to jet flame impingement must withstand temperatures up to twelve hundred degrees Celsius while under mechanical load.
Testing Methods
Standard tests use burner setups or actual sacrificial cells to blast prototype thermal barriers. Designing to resist this flame requires composite materials such as mica sheets or ceramic matrices. These materials block the heat and delay thermal propagation to the passenger cabin.
Sourcing Impact
Sourcing teams evaluate thermal barrier sheets by their resistance to these high-speed flame events. This rating determines which materials are certified for the battery pack casing.
