Exploring e-Mobility Materials: Silicones vs. Polyurethanes

From your experience, what are the main applications for polyurethane foams in mobility?

Polyurethane foams are widely used in EV battery systems, charging stations and energy storage systems (ESS). These foams have good dielectric strength, which helps ensure safe electrical operation — a necessity for EVs and their related systems. Additionally, I’d like to highlight that properties such as their inherent tack and optional removable PET liners make them easy to assemble and integrate into various components in a battery pack.

Polyurethane foams offer flexibility in terms of density and design, allowing manufacturers to tailor them for specific applications such as:

• Compression pads: Polyurethane foams are commonly used in EV batteries to manage cell swelling during charging and discharging cycles. The right foam ensures optimal pressure on the battery cells, maintaining their performance and helping to extend the range of the vehicle.
• Vibration dampening: In EV systems and charging stations, polyurethane foams can help absorb vibrations and enhance structural integrity, which is crucial to ensuring smooth and long-lasting operation. This makes these foams ideal for applications within EV cooling plates and charging systems.
• Cushioning and assembly: Polyurethane foams can be customised in terms of thickness (from 1 mm to 12 mm) and density (150 kg/m³ to 350 kg/m³), making them ideal for applications requiring specific levels of compression and cushioning.

Looking at the polyurethane foams offered by Tape Solutions, could you highlight key products that are vital for e-mobility applications?

Of course. A few notable series of polyurethane foams include:

• PF27 Series: A thin-gauge foam, specifically developed for efficient functioning of batteries in a pack. This series ranges from soft to firm foams and also has a UL 94 HBF flame rating. This foam has thermal insulation properties that help to maintain the cell face temperature. For long battery life, uniformity of cell temperature and cell pressure are key. This foam, compressed between cells, creates uniform pressure over the cell surface. These properties and the resulting function of the foam are very consistent over time and across a range of environmental conditions, ensuring a long life for the pack.
• PF47 Series: Available in various densities, this series is perfect for battery pack applications that require both compression strength and flame retardancy.
• PF100 Series: A low-density foam with a flat compression curve in addition to a high compression set resistance, suitable for applications where structural durability is important.
• PS-V0 Series: A high-performance polyurethane foam with a V0 flame rating. It offers excellent water sealing and compression set properties, and provides UL94 V-0 properties, making it a go-to for EV battery packs and ESS sealing applications. This series meets the stringent safety standards for the most challenging environments and applications where flame and fire protection are of the highest importance.

Could you highlight the main benefits of using polyurethane foams in mobility?

Yes, these materials are engineered for mechanical cushioning. They provide a consistent deflection force and also have a low compression set. They have very good dielectric strength, which helps ensure safe electrical operation.

Additionally, their features are tunable for ease of assembly and design. For example, these foams can be custom-produced over a wide range of thicknesses from 1 mm to about 20 mm. The density of these foams can also be tuned anywhere from 150 kg per cubic metre to about 350 kg per cubic metre. The surface texture is another feature that we can customise as well.

While these foams have an inherent tack, we can modify that to make it non-tacky, but the inherent tack helps them adhere to substrates like aluminium backings without the need for an additional adhesive layer, making it cost-effective.

We can also provide these foams with a removable or a permanent PET liner for ease of assembly.

Looking at the applications in EV batteries, many of these PF Series Foams are recommended for cell-to-cell compression pad applications to manage cell swelling during routine operations and as cushioning pads on the cooling plate to provide structural stability under constant pressure.

Silicone foams, in comparison, are often recognised for superior performance in extreme temperature environments and applications requiring enhanced flame resistance. Whether it’s automotive electronics, EV insulation systems, or gaskets, silicones have long been a reliable choice where durability and long-term performance are crucial.

How do silicone foams compare to polyurethane foams in mobility applications?

Silicones excel in extreme environments and are often a preferred choice for applications that demand 3 key attributes: 

• Water sealing
• Temperature stability
• High-flame resistance

Silicones also offer a very long service life, which is advantageous in the mobility market where a component failure after 5 years, for example, could be a massive disruption if it takes an entire train out of service.

In your experience, what are some of the key silicone foams used within mobility applications?

Yes, some of the main silicone offerings I would like to highlight include:

• F-20: As the name implies, it's a 20 pound per cubic foot foam. It's typically used for power supply devices, automotive electronics, electrical insulation and vibration mounts. We currently offer it in grey and black and a variety of thicknesses all the way up to 12.5 millimetres. This foam offers excellent vibration dampening and durability in demanding environments. It also meets the UL94-V0 rating with material as thin as 1.6 mm unsupported.
• F-15: This is a mid-range density foam, at 15 lb/ft³, and is the newest addition to our silicone portfolio. It has great water sealing, excellent resistance to ageing, compression set, and also a great compression deflection. It is typically marketed for applications within aerospace, rail, lighting, and automotive markets. This product is mid-point between the F-12 and F-20 Series where for some applications an F-20 exceeds the basic requirement but the F-12 is not quite enough.
• F-12: The lowest density foam coming in at 12 lb/ft³ nominal is also the softest grade offered. It is often utilised in medical equipment, and within lighter duty mobility applications where flexibility is key. Also commonly used in applications where there are weight restrictions such as aerospace.

All of our silicone foams can be made with different surface finishes ranging from smooth to matte to full texture on one or both sides. The surface finish of the product can often be overlooked, but most applications—especially those involving automation—can be impacted by this feature.

The choice between polyurethane and silicone foams ultimately comes down to the specific requirements of an application. Let’s examine two key considerations:

1. Cost-effectiveness: For cost-effective solutions with customisable compression and flame-resistant properties, polyurethane foams are an excellent choice. Their adaptability to various densities and thicknesses allows them to be tailored to specific design and performance needs. This is particularly relevant in battery compression pads, cooling systems, and charging stations.
2. Demanding environments: For more demanding environments, especially where extreme temperature, water sealing or enhanced flame resistance is required, silicone foams offer superior performance. Whether it’s vibration dampening in automotive electronics or long-term water sealing in EV gaskets, silicone foams provide greater durability and the reliability necessary for critical mobility components.

Both silicone and polyurethane foams offer significant benefits to the mobility industry, each excelling in specific areas. For charging stations and general e-mobility applications, polyurethane foams are a lightweight, affordable, and customisable solution. They are designed with manufacturing placement processes and automation in mind.

On the other hand, in environments where long-term durability and fire safety are paramount, Norseal Silicone Foams are the clear choice.

Ultimately, selecting the right foam material depends on the application-specific performance requirements. Contact our team to discuss what materials and products our portfolio has to offer for your specific application.