A high-end electric vehicle (EV) uses an average of 40–50 kg of adhesive, more than seven times that of a traditional internal combustion vehicle. Behind this “adhesive revolution,” silicone, as a key base material, plays five “hidden roles” deeply embedded in battery pack safety and performance—from heat conduction to cushioning, from insulation to cooling. Every drop is crucial for overall vehicle safety.
Industry estimates show that a single power battery pack contains 3–8 kg of silicone-based materials. Its key roles include:
Flowing Framework for Thermal Gels
High-purity linear silicone oil (viscosity 50–1000 cSt) serves as the base, giving gels low thermal resistance (<0.2 ℃·cm²/W) and long-term pump stability. Requirements: metal ions <1 ppm, volatility <1% @150℃ to prevent high-temperature precipitation and blockage of channels.
Insulating Barrier in ECU Encapsulation
Phenyl-modified silicone oil increases heat resistance above 200℃ while maintaining dielectric strength >30 kV/mm. In OBCs (on-board chargers) and DC-DC modules, it prevents high-voltage breakdown and moisture ingress.
Elastic Protector for Battery Housing Sealants
Hydroxyl or vinyl silicone participates in crosslinking to ensure sealants maintain >300% elongation at break during –40℃ to 120℃ thermal cycling, resisting vibration and thermal expansion stresses.
Safe Medium for Immersion Cooling
Low-viscosity (<5 cSt), high-flashpoint (>180℃) silicone oil is used in liquid cooling systems that directly contact cells, providing high insulation and material compatibility without corroding copper foils or aluminum casings.
Shock-Absorbing Core for Module Pads
High-phenyl silicone imparts excellent compression set resistance to silicone rubber (70℃×22h <15%), absorbing collision impacts and preventing cell displacement or short circuits.
“Silicone used to be just an additive; now it is a functional carrier,” says a materials engineer at a leading battery manufacturer. To meet automotive-grade requirements, suppliers must provide IATF 16949 certification, AEC-Q200 test data, and batch traceability.
With the rise of 800V high-voltage platforms and integrated die-casting technology, the per-vehicle value of silicone has risen from hundreds to thousands of yuan. For domestic silicone manufacturers, the ability to reliably deliver high-purity, low-impurity, scenario-customized products is the key entry ticket into the EV supply chain.
In this wave of electrification, the quietest material—silicone—is becoming the most indispensable cornerstone of safety.
