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2024-02-21
Silicone foam's unique combination of properties makes it an indispensable material in thermal management systems for electric vehicle (EV) batteries. In this article we explore its various attributes and applications in improving safety and efficiency of EV battery packs.
Characteristics of Silicone Foam
1. Density: Silicone foam's base density is 1.17g/cm3, however with modern foaming technologies its density can be reduced as low as 0.16-0.20 g/cm3. Its lightweight characteristics make it suitable for automotive components like car seats and headrests while conventional silicone rubber foam materials with densities of 0.45 g/cm3 are widely used for sealing and vibration damping applications.
2. Flame Retardancy: Silicone foam enhanced with flame retardants offers excellent flame-retardant properties, earning a UL94-V0 rating and significantly lowering fire-related risks in electric vehicles. This feature can prove extremely valuable.
3. Electrical Insulation: Silicone rubber tends to lose some of its electrical insulation properties when added with physical fillers, impacting volume resistivity and surface resistivity while increasing dielectric constant and dielectric loss factor. Although fillers may compromise silicone foam's electrical insulation properties in certain ways, silicone foam remains an option for applications requiring both thermal insulation and electrical safety.
Applications in EV Battery Thermal Management
An electric vehicle's battery is at the core of its propulsion, yet can present serious safety risks if mismanaged. Batteries produce heat during operation which may lead to expansion and possible cell damage as a result of prolonged friction between cells. Furthermore, battery packs for EVs typically exceed 200V in output voltage and require waterproof enclosures with IP67 waterproof ratings to protect them from short circuiting caused by water ingress;
Silicone foam plays an essential role in meeting these challenges:
Thermal Expansion Management: With its superior compressibility and recovery characteristics, Thermal Expansion Management possesses high compressibility and recovery properties to limit deformation caused by thermal expansion/contraction during charging cycles, thus providing durability, low shrinkage/impact absorption/flame retardancy (UL 94 V0 level) to battery cells.
Waterproofing: Silicone foam offers exceptional waterproofing properties, ensuring devices remain dry and functional in various environments.
Dimensional Stability: Dimensional stability provides long-term compression set with minimal long-term compression set, effectively preventing any deformation to dimensions.
Flame Retardancy: Our material's superior flame retardancy helps mitigate risks related to thermal effects during battery operation, thus protecting against thermal effects on cells and batteries.
Customizability: Silicone foam can be customized to meet specific requirements for thickness and strength, offering optimal sealing performance with low internal stress levels, helping avoid warping or arching of seals.
Heat Dissipation in Battery Modules
Thermally conductive silicone pads are often employed to keep internal battery temperatures within 5degC, providing even temperature distribution across each cell and prolonging battery lifespan and performance during operation. By adhering to this regimen, this arrangement not only ensures uniform temperatures across a battery pack's modules but also helps extend their lifespan and ensure stable operation over time.
Thermally conductive silicone pads transform the point of contact between batteries and cooling tubes into surface contact, improving individual cell temperature uniformity and increasing overall thermal capacity - ultimately decreasing average battery pack temperatures.
Silicone foam's unique properties, including low density, excellent flame retardancy and electrical insulation as well as its ability to regulate thermal expansion and provide waterproof sealing capabilities make it an invaluable material in thermal management systems for electric vehicle batteries. As such, its use ensures safety, reliability, efficiency, as well as sustainable transportation technologies advancement.
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