Overcoming OEM EV Challenges and Complex Technologies

When asked to describe the role of an applications engineer at Tape Solutions, Patricia shared that the primary goal is to ensure that the materials used within EV applications meet the stringent specifications and performance requirements that are set by OEMs. As an applications engineer, she is responsible for qualifying the foams and tapes based on specific application needs and ensuring that they meet either ASTM or ISO standards for mechanical, thermal, and electrical properties.

The applications engineering team at Tape Solutions has a global footprint with local support and testing capabilities in Asia, Europe, North America, and India. This global network of subject matter experts ensures that the team can share lessons learned between regions, provide quick support to a global customer base, and participate in worldwide industry conferences to keep a finger on the pulse for emerging technologies and trends.

In cases where customers have a set of different property or testing requirements, applications engineers are well-equipped to provide the internal testing and technical expertise that the customers need.

But, why is it important to work together with OEMs to question, improve upon and adapt common test methodologies?

Without a doubt, the EV market is moving at lightning speed. Patricia shares that changes are unavoidable — whether they involve the cell format and chemistry or a new technology for thermal protection. And, because of this, it is unrealistic to specify or qualify the same material per the same test methods and conditions for all battery pack configurations. She shared that each OEM (or even the same OEM in different regions) has its own requirements and test criteria. In her role, she can leverage the material expertise of our internal Tape Solutions teams to provide the necessary support to OEM technical engineers. The applications engineers help explain to end-users how each material could behave under certain environmental conditions. They demonstrate which conditions could be too harsh for the nature of the material and explore which properties could be tuned to improve performance. The primary goal of an applications engineer is to support material specifications and test methodologies OEMs require. Standardizing test methods based on OEM requirements is key for helping make “apples to apples” comparisons when benchmarking materials.

Some of the most common EV challenges include managing cell swelling, improving thermal management, mitigating fire propagation, improving cell structure, protecting against environmental factors and providing electrical insulation. The applications engineering team works tirelessly to test and validate products to best evaluate material performance when it comes to standing up to these challenges. To do this, the EV team carefully considers application categories based on the critical performance of the material and the main function of each application. Let’s break it down by some of these challenges.

1. Managing cell structure & improving cell structure

When it comes to this critical issue, Patricia and Senthil put the spotlight on our R&D team. This team plays a fundamental role in coming up with several different types of foam configurations to ensure that the products will have the necessary properties and performance criteria for each specific application, which differs based on the type of cell (pouch vs. prismatic).

For each of these foam configurations, the main property is foam compressibility as customers are most interested in properties such as force to compress, compression load deflection, and compression set.

The applications engineers run tests to ensure that the foam is not too soft or too stiff. If it is too soft, the cell expansion over time will damage it. If it is too stiff, the deflection force of the foam will apply a higher pressure on the cell, creating issues.

2. Providing protection against environmental factors

Gasketing materials serve the purpose of protecting the battery pack from environmental factors. As an applications engineer, Patricia often tests water sealing per IP67, which is a test method commonly used on electronics as well. While this is the most common test, other tests are also available per customer request. For example, our teams also test under U-seal format to test if the foam, under compression, can effectively protect against water ingress for a specified period of time. In terms of sealability, compression set is a very important property because it is critical that the material always fills the gap between battery components. If the foam degrades too quickly, sealability performance is lost.

Another test methodology is what the applications engineering team refers to as “Foam Life Estimation Analysis based on C-Set.” This test was developed to help understand exactly how long the materials can perform when exposed to ideal conditions, however, it also allows engineers to estimate extreme scenarios where the foams could degrade faster.

3. Improving thermal protection and mitigating fire propagation

Perhaps one of the most critical challenges in EV development is protecting battery packs from thermal runaway events. Therefore, applications engineering teams are very focused on selecting materials that can withstand extreme temperatures and help prevent fire spread. At Tape Solutions a common test is the torch test wherein materials are exposed to temperatures up to 1300°C to ensure material survival in these extreme conditions and the ability to help protect adjacent cells.

The team shares that it is also important to look at material survival at thin gauges (due to vehicle weight constraints) and its ability to survive the grit or aluminum particle exposure.

OEMs realize the critical nature of ensuring these protection measures are in place. However, these requirements are not yet well defined or standardized, with temperature and exposure times often varying between customers. Based on the application, we’ve seen different flammability requirements referencing UL94, from HBF up to V0 ratings. Late in 2023, UL released UL2596, a TaG (Torch and Grit) test method to screen material’s thermal resilience when exposed to both flame and blasting of aluminum particles, looking to simulate a thermal runaway event. While this is not a pass/fail test method, it could be used as a guidance or reference in understanding material’s performance; however, OEMs can also have their own TaG test method. Without a doubt, OEMs are looking to optimize, as much as possible, materials that can provide high thermal performance at low thickness and competitive prices. While tricky, this is the ideal combination.

Different battery chemistries require different approaches to material selection. For example, Lithium Iron Phosphate (LFP) batteries are less aggressive during thermal runaway events compared to Nickel Manganese Cobalt (NMC) batteries which tend to present higher risk due to their nickel content. When helping make material selections, our teams take these differences into account to ensure each material can provide the appropriate level of protection based on the battery chemistry and the risk associated with each type.

Patricia highlighted that LFP cells are mainly used for lower mileage purposes whereas the NMC are meant to achieve a longer mileage range. And, when it comes to material selection, it is essential to closely examine capabilities for fire propagation protection in case of a thermal runaway event. There are screening tests that help evaluate the thermal properties of the material. Some of these tests include Torch Flame, Hot Plate and a recent TaG (Torch and Grit). The flame temperature on the Torch test goes from 1000°C up to 1300°C, based on OEM requirements and the main goal is to evaluate the temperature on the cold side of the sample (opposite side of where the torch is applied) to understand the material’s thermal resilience. Ideally, the longer the material could prevent showing any type of degradation (hole through), means the longer the protection it provides, and that it is suitable for a specific application.

Patricia and Senthil explain the three primary cell formats in EVs:

• Prismatic
• Pouch
• Cylindrical

Each comes with its own set of challenges and advantages. While our team does not offer liquid dispense solutions, which are required for battery packs built using cylindrical cells, our teams do offer solutions that align with prismatic and pouch cell formats.

Prismatic cells require stiffer foams for precise load deflection, while pouch cells experience greater expansion and require materials that can adapt to these changes. The Tape Solutions team can customize materials to suit each battery format and align with the OEMs design and performance goals. Applications Engineering and R&D teams work together to define, for each type of cell, the minimum material performance for compression pad solutions and thermal protection materials.

As the EV industry continues to grow, applications engineering teams continue working together with R&D, our global team, and our customers to ensure reliable, high-performance materials. With the industry on the cusp of several exciting innovations such as those associated with solid state batteries (which promise better thermal performance) and immersion cooling (which involves submersion of cells in electrically insulative oils to prevent thermal runaway), the Tape Solutions team is closely monitoring the impact of these technologies on the materials needed to support them.

From thermal protection to customization for different battery technologies, the applications engineering team is dedicated to helping develop the next-generation of electric vehicles. One of the most significant advantages of our collaboration with customers and OEMs is our ability to adapt test methodologies to meet the specific needs of each customer. This flexibility is key for improving material performance, enhancing testing protocols, and ultimately ensuring the best solutions for unique challenges.

While our team does offer a standard product portfolio, perhaps one of the biggest advantages for our customers is our ability to offer customized solutions.