Enhancing Mechanical Stability in EV Battery Packs

Managing heat accumulation within EV battery packs remains one of the biggest engineering challenges. Automakers must maintain cells within an optimal operating range. It differs between battery types, designs, technologies and chemistries but ranges typically between 20°C and 45°C with occasional peaks up to 60°C for safe performance. When temperatures rise rapidly due to abnormal conditions, a thermal runaway event can be triggered and without proper mitigation, it can rapidly spread to the adjacent cells.

Our Norseal® TRP Series materials are designed to support this challenge. While their primary role is heat absorption and flame‑resistant insulation, they also contribute to mechanical stability by helping compartmentalize modules and maintain structural spacing. The reinforcing effect subtly improves pack robustness, acting as a complementary layer to cushioning materials used at the pack level.

Patricia, what additional mechanical or thermal behaviors should engineers consider when selecting multi‑functional protective layers for cell‑to‑cell separation?

As previously stated, mechanical and thermal behaviors will be highly dependent on the cell’s format and chemistry. A prismatic cell will not show the same wall expansion over its lifespan as a pouch cell would and an LFP battery compared to an NMC one will not have the same thermal stability, so it’s always important to start by understanding the cell technology.

Both prismatic and pouch cells lifespan can be enhanced by having a compression pad between cells that would always maintain pressure on the cell’s wall. It’s important to take into consideration cell expansion and optimal pressure to define the best compression pad technology.

Regarding thermal performance, depending on cell chemistry and the battery pack design, we could offer a multi-layer solution that will provide both mechanical and thermal performance. The multi-layer construction will mainly consist of a compressible foam that will provide mechanical performance and a high temperature resistance, flexible layer that will boost thermal protection. Finding the right combination is a challenge we are always eager to overcome!

Inside every battery module, intercell pads play a critical role in managing the expansion and contraction of pouch and prismatic cells. As cells swell over thousands of cycles, they require a controlled, consistent pressure to:

• Maintain ideal performance
• Preserve electrical pathways
• Enhance lifetime of the cell
• Prevent mechanical damage over the battery’s lifetime

These pads are engineered with a defined Compression Force Deflection (CFD) profile, meaning they apply a precisely tuned force over a given compression range. If the force is too low, cell performance and lifetime decreases. If too high, cell stability and performance may be compromised.

Saint‑Gobain engineers collaborate with EV manufacturers to identify the optimal CFD range, ensuring consistent force retention even after long‑term temperature exposure and mechanical cycling. 

Patricia, what CFD shifts (fresh vs. aged) do we typically observe in real customer applications, and what factors most influence force retention?

It is well known that EV requirements evolve quite fast, and this mechanical property is one of those requirements, however it’s known that the pressure required at BOL (fresh, beginning of life) will always be less than the pressure required at EOL (aged, end of life).

The CFD shift between fresh and aged samples will rely a lot on the material‘s formulation and temperature resilience under compression. Some material technologies that are exposed to high temperatures over a long period of time, could show a permanent set, harden and lose their viscoelastic capability which could have a negative impact on the cell’s performance by not providing the required pressure.

It is a standard accepted practice to provide stress/strain curves for fresh materials when tested at room temperature but, over time—and due to the operating temperature the battery packs can be exposed to—the engineers started looking into any performance impact and data to backup the material’s behaviour. We can offer cyclic compression curves at different temperatures that show our solutions resilience, providing confidence to our customers that force retention will not be an issue.

While intercell pads stabilize cells inside a module, cushioning pads are meant to protect the entire battery pack from external vibration coming from the road when driving the vehicles. These materials are typically made from polyurethane or microcellular foams and are engineered to:

• Absorb and dampen vibration
• Minimize impact loads
• Maintain low compression set
• Preserve structural alignment under long‑term cycling

Cushioning pads help prevent excessive mechanical stress on module housings and pack components. They compensate for tolerances, distribute loads uniformly, and help the pack maintain form and function despite significant dynamic forces.

Improved pack‑level mechanical stability helps increase EV durability expectations and extended lifetimes.

Patricia, what long‑term compression set or rebound behaviors are most critical for cushioning pads in under‑floor battery packs?

Cushioning pads' main functionality is to always close the gap in between components that need to be protected from vibration, usually placed in between cooling plates and battery pack housing. Compression set is a good property that can help identify the proper material technology that will not deformed over time, losing its viscoelastic capabilities and create a gap in between components that will lead to vibration issues.

We usually propose a life estimation analysis based on maximum allowed compression set. We age our materials using some accelerated aging conditions based on the material’s technology and then use Arrhenius extrapolation to have a better idea of long-term performance.

What real-world improvements have customers observed from engineered cushioning pads?

Cushioning pads have been used by automotive OEMs for several applications mainly to reduce the noise that can travel through the passengers compartment, negatively impacting the driving experience. The quieter the cabin is, the better is the driving experience. However now we are also talking about safety when a cushioning pad is needed inside the battery pack, if this high-performance solutions are not included in the design, vibration and undesired crashing between components can happen inside the battery pack that could lead into safety risks.

Manufacturability is essential, especially as battery volumes scale globally. Both intercell and cushioning pads can be engineered with features that improve assembly speed and consistency:

• Surface tack to hold components in place during assembly
• Liner and pull‑tab options for automated or manual placement
• Customized hardness and CFD for consistent gap‑filling
• Material surface handling properties for precise pick‑and‑place

Our compression pads and other foam solutions can be tuned so that assembly steps remain stable and repeatable, reducing variability and production delays.

Patricia, which geometric or liner‑based features have proven most effective at improving placement accuracy in automated lines?

I wish I could say there is an option that will fit all applications, but that would be too easy! Commonly, finger lifts are incorporated during the conversion process to ease automated assembly at the customer’s facility, this finger lift geometry can be designed as needed based on the automation equipment and its capabilities. The finger lift can be as short as possible (a few mm) or sometimes larger to accommodate the robot feature/arm that will grab the finger lift to remove the protective liner. This feature is basically defined project by project.

Battery components must withstand combined mechanical, thermal, and environmental stresses far beyond standard laboratory tests. Saint‑Gobain supports customers with application‑specific validation, enabling early insight into material behavior before full prototypes are built.

Typical evaluations include:

• Compression set testing at various temperatures and dwell times
• CFD measurement before/after aging
• Vibration and shock testing for cushioning materials
• Thermal cycling and environmental aging
• Combined mechanical‑thermal tests that replicate real EV operating conditions

This internal capability helps ensure that compression pads and cushioning pads maintain their performance over the full expected life of the battery.

What combined testing sequence (thermal + mechanical) most accurately predicts long‑term field behavior for mechanical pad materials?

I would say that cyclic compression at different temperatures provides relevant data and confidence regarding long-term material’s perfomance.

Thank you, Patricia, for providing expert insight into how compression and cushioning pads can improve mechanical stability across the entire battery system. From managing inter‑cell pressure to protecting pack‑level structures with cushioning pads, Saint‑Gobain Tape Solutions offers materials designed to support the evolving durability standards of modern EV platforms.

As EV battery technology evolves and batteries become thinner, more energy‑dense, and subject to harsher duty cycles, addressing both micro‑scale (cell/module) and macro‑scale (battery pack) mechanical behavior will be essential to achieving the next generation of performance and safety benchmarks.

Our engineering teams welcome the opportunity to share deeper insights with you and tailor recommendations to your application.