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.
Mica Barriers
Meaning
High-temperature sheet insulators composed of naturally occurring silicate minerals prevent heat transfer and electrical shorting between adjacent battery cells. Installed between modules, mica barriers block the intense thermal radiation and flame fronts during a runaway event. They maintain mechanical integrity at temperatures exceeding one thousand degrees Celsius.
This protection is limited to dry applications because moisture can degrade the binder material. In addition, their brittle nature requires careful handling during assembly.
Dielectric Strength
High resistance to electrical breakdown prevents hazardous voltages from bridging across modules during a thermal failure. In high-voltage packs, mica barriers ensure that the metallic structures of the housing do not become energized. This containment of electrical energy is necessary for first responder safety.
Thermal Resistance
Low thermal conductivity prevents the rapid heating of adjacent cells when a target cell experiences a thermal spike. By slowing the rate of heat conduction, mica barriers delay or entirely prevent the onset of cascading runaway. This delay gives vehicle passengers more time to evacuate.
Material Composition
Thin laminates created by binding mineral flakes with silicone resin offer both flexibility and strength. Depending on the design requirements, mica barriers can be reinforced with glass fiber or ceramic fabrics. This composite construction allows the sheets to resist the mechanical forces of venting gas.