Selecting insulation materials for battery liquid cooling plates is crucial to ensuring the safety, efficiency, and longevity of electric vehicle (EV) battery systems. Given the increasing performance demands and higher operational voltages in modern EVs, traditional insulation methods such as PET films (“blue film”) are now being replaced by more advanced solutions, including UV-coated insulation materials.
Historically, PET-based insulation films (often referred to as “blue films”) were the industry standard for battery insulation. However, with the advent of higher energy densities and voltages—especially with the emergence of 800V platforms—these traditional materials have started to fall short in several key performance areas, including adhesion and electrical breakdown.
The widespread use of “blue films” for insulating battery cells stems from their chemical resistance, insulation properties, and tensile strength. However, there are significant limitations:
Blue films have limited adhesion strength, especially in high-vibration environments like automotive applications. The adhesive layers (PSA) used in blue films can easily undergo cohesive failure, which weakens the overall structural integrity of the battery pack. As a result, battery cells are more likely to detach, leading to potential short-circuiting.
With the push for faster charging times and higher energy outputs, battery systems are moving to 800V platforms. The limited dielectric strength and adhesion properties of blue films make them increasingly inadequate for these high-voltage applications.
In response to these limitations, companies like BMW and Parker Lord have pioneered new insulation solutions using UV-coated materials. These materials offer a range of advantages over traditional films:
UV coatings provide much stronger adhesion compared to PET films. This results in better structural integrity, as the insulation material bonds more effectively to both the cooling plate and the battery cell.
With dielectric strengths of up to 81 kV/mm, UV coatings ensure reliable electrical insulation even at higher voltages.
Unlike powder or epoxy coatings, UV coatings cure quickly under UV light, allowing for rapid application and reducing production time significantly.
Let’s break down the performance of different insulation materials in key areas relevant to battery cooling plates.
Dielectric Strength: PET films and UV-coated insulation materials perform similarly well in dielectric strength, but powder coatings fall significantly short.
Adhesion Strength: UV-coated insulation materials outperform both PET films and epoxy coatings in adhesion strength, providing more robust protection in high-vibration environments.
Curing Efficiency: UV coatings offer unparalleled curing speed. While powder and epoxy coatings require lengthy heating times, UV coatings solidify within seconds under UV light, significantly boosting production efficiency.
The primary driver behind the shift from PET films to UV-coated insulation in companies like BMW is adhesion performance. In high-voltage battery packs, poor adhesion can result in delamination, where the insulation peels away from the battery cell, leading to electrical shorts and safety hazards. UV coatings, with their superior bonding properties, resolve this issue by providing stronger and more durable adhesion.
When applying insulation coatings, achieving the correct thickness is critical. UV-coated materials are typically applied at 100 microns under 5000 volts, ensuring they meet the necessary dielectric requirements without interfering with the cooling plate’s thermal performance. The spray process must be carefully controlled to ensure consistency, particularly in dust-free environments. Any contamination during the spraying process can compromise the integrity of the coating.
One of the significant advantages of UV-coated insulation materials over powder and epoxy coatings is the speed of curing. UV coatings can cure in a matter of seconds under a UV light, compared to the 10–30 minute heating times required for traditional coatings. This not only accelerates production but also reduces material waste and energy consumption, making UV coatings a more sustainable choice.
With the rise of high-voltage platforms in the EV industry, traditional insulation methods like PET “blue films” are becoming obsolete. Companies like BMW have already made significant investments in UV-coated insulation technologies, and it’s likely that more manufacturers will follow suit.
The combination of strong dielectric performance, superior adhesion, and rapid curing makes UV coatings the most promising solution for next-generation EV battery systems. As production processes continue to evolve and the technology matures, UV-coated insulation materials are poised to become the industry standard.
Selecting the right insulation material for battery liquid cooling plates is critical to ensuring the safety, efficiency, and longevity of electric vehicle battery systems. UV-coated insulation materials, offer a superior combination of dielectric strength, adhesion performance, and production efficiency. They resolve many of the limitations of traditional PET films and are better suited to the high-voltage, high-performance demands of modern EVs.
By addressing challenges such as spray thickness, adhesion, and curing time, UV-coated insulation is not just an upgrade—it’s a necessity for the future of electric vehicle battery technology.
I've worked in battery thermal management for over 5 years, handling lots of international projects. If you're curious about battery liquid cooling products or services, feel free to ask me any questions!
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