How to improve heat dissipation and EV battery lifetime

Sponsored by Von Roll

Next-Generation Adhesive Products for Battery Applications 

How to improve heat dissipation, productivity and lifetime performance of battery modules and packs

As the current trend is moving away from conventional ICE (Combustion Engine) power train systems to fully or hybrid electric systems, there is a strong demand and need for next-generation materials for the 48V, 400V and 800V battery platforms. Von Roll is specialized in electrical isolation materials like impregnation, potting and coating resins but also in flexible laminates for electrical, electronics and battery applications. For all type of batteries, we are historically known for cell-spacers technology based on mica-chemistry and adhesive systems 

Generally, a distinction is made between two different adhesive technologies: self-levelling adhesives and thermal adhesives.

Self-levelling adhesives are also often called “potting adhesives” – as the name suggests, they are low-viscosity adhesives used in the battery pack assembly for various purposes. They offer an ideal combination of gap filling and cell fixation, in what we call a “cast and forget” approach, along with thermal and mechanical shock dampening. Since they produce characteristically homogeneous heat dissipation from the battery, self-levelling adhesives also contribute to a longer battery life overall. On the operation side, they also carry other advantages, as they allow shorter production cycles and eliminate the need for additional gap filler materials.

On the module level, our self-levelling adhesives are mainly used for three different applications. As venting cap protection, they are very effective against corrosion and promote controlled expelling of venting gas with reduced fire risk while also fixing and protecting bonding wiring. When used for bottom part fixation, self-levelling adhesives offer excellent heat dissipation, shock damping, and increased crash stability without the need for gap filler or structural adhesives. In a full potting scenario, self-levelling adhesives provide the highest-level module protection with the most effective homogeneous heat dissipation, thermal runaway protection, and ultimate shock damping.

For high-volume productions, a combination of venting cap protection and bottom part fixation potting can be a very effective solution because there is no need for additional products like gap-fillers, gap-pads, structural adhesives, or mechanical fixation. For further information on this all-round approach, look at the following videos:

Dosing of Damival® 13682 in Battery Modules

Dosing of Damival® 13682 in E-Bike Batteries

To demonstrate the heat dissipation effect of our self-levelling adhesives, we performed thermographic comparisons of the heat flow in single battery cells. A significantly more homogeneous temperature distribution than conventional gap filler, foam or gap-pad was achieved. 

Figure 1: Comparison of heat dissipation between gap-filler and our Damival 1368x Series

For the potting 1368x Series, the thermal runaway behaviour has been tested in fully potted high-voltage battery modules. The result: below the potted areas without oxygen access, no reaction could be observed – flames were extinguished in 3 Seconds. The thermal runaway was also slowed down significantly – after 15min, the superior heat dissipation already produced a marked decrease in maximum temperature, which went down further to below 40°C after 50min. The full and detailed report is available on request.

Figure 2: Thermal runaway test of a fully potted module with Damival® 13682

Next-level: The Damival 1368x Series 

Tested, proven, and certified for battery applications, this resin is   Eco-friendly, thanks to the use of next-generation polyurethane (Health and Safety friendly). As a high temperature resistant Polyurethane, outgassing-free alternative to silicone potting materials, it is suitable for use up to 150°C, highly elastic up to 200% elongation, and exhibits excellent thermal shock behaviour. With a wide range of approvals, this product is non-flammable, self-extinguishing and classified as a non-dangerous good for easy transport. The overall versatile material is suitable for a range of applications from PCB-potting (Printed Circuit Boards) to use as an adhesive.

Thermal adhesives are also known as thermal glues and are mainly used for the mechanical fixation and thermal connection of modules or packs to the cooling system. They can provide additional sealing to prevent moisture migration which could affect the long-term performance of the battery.

Fixation on module/pack level for thermal connection to the cooling systemThermal & mechanical shock dampingGood adhesion on a broad substrate spectrumHigher productivity – mechanical fixation replacement and extra sealingHigh thermal conductivity over 2.5 W/mK for heat dissipation

Figure 3: Battery module of prismatic cells with thermal adhesive (red) used

Thermal adhesives are suitable for use on modules or packs in all used-cell technologies like prismatic, pouch or cylindric cells. 

At the module level, thermal adhesives provide cell bonding and fixation, connect the cells to the cooling system, and support module sealing. When used for fixation at the pack level, the modules are mechanically bonded to the pack, the BMS (Battery Management System) unit is secured, a connection to the pack cooling system is established, and the battery pack gets additional sealing. As a thermal glue in other applications, the adhesive can serve to fix BMS units and cell stacks, provide homogenous heat dissipation, dampen shocks, enhance crash stability, and function as a seal against humidity and moisture.

Next Level Thermal Adhesives based on Damival Series

Tested and proven in battery applications, this is a health & safety-friendly adhesive, thanks to the use of next-generation polyurethane (health and safety friendly). As a non-silicone, outgassing-free alternative to silicone potting materials, it is suitable for use up to 150°C.  This highly flexible resin, exhibits excellent thermal shock behaviour, and, in addition to its high thermal conductivity of 2.5W/m.K, its low glass transition temperature (below -45°C) allows keeping high elasticity even at low temperature. Non-flammable, self-extinguishing and classified as a non-dangerous good, it is easy and safe to transport.

If you have any questions about our products and how they might work best for you, please contact our experts directly: alexander.teufl@vonroll.com or at www.vonroll.com

Von Roll is one of the most traditional industrial companies in Switzerland. Origins date back to 1803. For more than 100 years, Von Roll has been supporting our customers in the challenges of electrification and energy generation. As the industry leader for electrical insulation systems, Von Roll is driving the global electrification. The products are essential for the ongoing industrial transformation to zero emissions.

Sponsored by Von Roll