Module Level Thermal Propagation Verification under EU Regulation Guidelines
EU battery regulation requires module thermal propagation testing with five-minute occupant warning signals before external flammability occurs.
Intumescent Silicone
Meaning
Elastomeric barrier material that expands upon exposure to high temperatures creates a protective insulating char layer. Often deployed in electric vehicle battery packs, intumescent silicone acts to prevent thermal propagation by blocking heat transfer between adjacent cells. It limits the spread of fire by swelling to fill empty spaces and voids in the module.
Its effectiveness decreases once the temperature exceeds the survival limit of the silicon dioxide residue.
Chemical Expansion
Thermal triggers cause the active additives in the rubber matrix to release non-flammable gases. This gas release forces the intumescent silicone to swell to multiple times its original thickness. The resulting low-density foam acts as a strong barrier against heat conduction.
Physical Barrier
High structural stability of the charred material resists the high-velocity gas jets produced during a cell rupture. This mechanical resistance prevents the intumescent silicone from being blown away or eroded by the venting effluent. It thereby maintains its insulating value throughout the venting event.
Application Method
Liquid dispensing systems allow for automated application of the material directly onto complex module surfaces. Unlike pre-cut sheets, intumescent silicone applied as a liquid conforms perfectly to irregular cell geometries. This precise coverage reduces weight while maximizing safety margins.