Are Silicones the Only Material Solution for EV Battery Protection?
Materials for EV batteries, automotive, transportation or aerospace are designed to maximize performance, energy density, space reduction and output. However, with the ever-increasing power density, the demands on thermal management and the prevention of exothermal events are also increasing.
In case of fire, electric shortcuts or overheating, there is no compromise in preventing heat or flames from spreading, but are widely used silicones the materials of choice for every application?
Let’s ignite the flame of enlightenment and take a deeper dive into silicone materials and the benefits innovative alternatives can offer in this post where we interviewed Saint-Gobain® Tape Solutions employees Alan Luna, EV Product Manager, and Boris Hosdains, Junior R&D Project Leader, to find out how to best achieve one common goal: Reliable protection without compromise.
In this article
- Why is there a risk of fire in EV batteries and how can tapes help mitigating the risk?
- Which materials are usually used for tapes in EV battery packs and which material properties do they offer?
- Where do you see potential issues?
- What is V-0 rating and are silicones the only option for V-0 rated fire protection?
- What are the advantages of this material and which applications do you see?
- Conclusion
Alan: EV batteries are designed to provide maximum performance and energy density in the smallest possible space – and engineers all over the world are trying to push the limits. The high current power generated during use, fast charge and/or discharge, as well as defects or accidents, can lead to overheating, electrical discharge or mechanical stress. This can cause failure inside the battery pack and potentially provoke a thermal event (i.e., production of toxic gases, flames and extreme temperatures).
Special materials like our tapes, foams and composites can solve a wide range of challenges like heat dissipation, prevention of arcing between cells, compensation of cell expansion, while ensuring mechanical and sealing properties. They can even help to protect adjacent cells from fire spreading in case of a thermal event.
Alan: Silicone materials combine the best of two chemical worlds like inorganic glass and organic polymers. Glass is known for its thermal and chemical stability while carbon-based plastics are versatile and suitable for various configurations (gums, fluid, solids foams) and shapes (pads, gaskets, sealants).
The latter properties of silicone polymer materials allow for creation of formulations that fulfill the demanding needs in EV battery pack applications. Silicone-based materials function in harsh environmental conditions like extreme temperatures and humidity, last a long period of time and are ideal where chemical and mechanical stability are needed.
Alan: Silicone materials provide unique properties, but their versatility and performance comes with a price. Silicone polymers can increase costs for battery manufacturers compared to using other organic-based polymers.
The rapidly growing demand for EV batteries can result in potential shortages and supply chain stresses and, consequently, price volatilities. Also, silicone polymers are made from silicone metal which is obtained from silica (SiO2) and require several processing steps where environmental impacts need to be considered.
Boris: UL94 V-0 is a flammability standard where the material must meet a series of criteria. Due to the high requirements, silicone materials usually meet UL94 V-0 criteria and are therefore a preferred choice. But don’t drop other materials like a hot potato. Polyurethane materials can also pass UL94 V-0 tests through fire retardant additives, but in doing so, the material loses important features.
Through intense research and development, we were able to solve this issue: Our Norseal® PS-V0 Series high-performance micro-cellular polyurethane foams combine UL94 V-0 standards with excellent sealing and material properties that fit best for EV battery applications without the use of silicone. By passing the vertical burn test, they meet the stringent safety standard for most challenging environments and applications where flame and fire protection are of the highest importance.
Boris: This product combines several key properties: In addition to the UL94 V-0 rating, PS-V0 is an excellent sealing material against water and dust ingress, making it an ideal sealing solution in EV & HEV batteries packs. The different thicknesses/densities available allow customers to select the solution that best fits with the FTC/CFD requirements – just like with our premium silicone solutions.
In addition, this product provides an excellent compression set even under the most difficult conditions (90°C), guaranteeing long service life. For sealing, fire-resistant or holding pad applications with a maximum use temperature of 100°C or less, PS-V0 is an excellent, cost-effective solution with premium performance.
Fire protection is a hot topic in EV and tapes can play key roles in maximizing fire protection of EV batteries and, besides commonly used silicone materials, there are UL94 V-0 silicone-free alternatives available. If you are burning to learn more, your tape experts can support finding the right solution tailored to your application needs.
“the highest performing and most expensive materials are not necessarily the ideal choice for every application. New materials with similar performance and special properties can offer distinctive advantages in modern EV battery design.”
— Boris Hosdains