Why You Need to Use Thermal Interface Materials in EV Batteries

As the automotive industry works to increase electric vehicle (EV) options and availability, it’s important for manufacturers like you to find high-performing EV battery solutions to meet the growing demand. In particular, these batteries need to offer increasingly optimized performance, such as longer battery life, without impacting manufacturing efficiencies.

Therefore, it’s important to consider how thermal interface material (TIM) may enable high performance while allowing for efficient processes. TIM includes thermal conductive adhesives (TCAs) to address EV battery optimization needs as well as thermally conductive gap filler to protect against overheating from air gaps. Learn about TIM along with TCAs and gap filler and how they help provide the performance and efficient processes you need for effective EV batteries.

How TCAs Play a Role in TIM:

TCAs help transfer heat away from a battery cell and provide electrical insulation to help prevent short circuits or overheating within the battery pack, helping extend the battery’s lifespan. As a result, they are compatible with the other materials used in battery pack assembly, such as electrode materials, current collectors and casing materials, helping to ensure that the components remain electrically isolated to reduce the risk of electrical faults. In particular, they offer:

• Temperature resistance: TCAs can maintain performance in -40°F to 302°F (-40°C to 150°C), which allows the EV battery to operate at different temperatures for charging, discharging and operational usage.
• Durability: TCAs protect against degradation with chemical, UV and humidity resistance. TCAs are also formulated to be compatible with metals, ceramics or plastics to prevent reactions between the adhesive and bonded materials. This helps reduce the likelihood of battery maintenance and replacement.
• Flexibility: Some TCAs are designed to remain flexible even after curing, which helps account for expansion and contraction as battery components experience heating and cooling. Flexible TCAs have the ability to absorb the stress to reduce the likelihood of mechanical failure. However, in situations where the structural component requires stiffness, gap filling, high compression or minimal migration, a TCA with less flexibility may be preferred.

How Gap Filler Plays a Role in TIM:

In conjunction with TCAs, gap filler helps prevent air pockets to further enhance the heat transfer. Minimizing these imperfections allows the overall thermal performance to perform efficiently and extend the battery life. In particular, gap filler provides:

• Hot spot protection: Air gaps between the battery cell and heat sink can lead to hot spots, which can damage the heat source due to inefficient heat flow. Gap filler protects the places where those hot spots would take place to help the heat flow temperatures stay consistent and avoid overheating.
• Conformability: Using a liquid, conformable gap filler allows you to fill microscopic gaps and imperfections between the battery cells and heat sink that you may not be aware are present. Further, the gap filler enables a more uniform heat transfer by smoothing out surface irregularities.
• Recyclability: Gap filler is removable and repositionable, helping reduce material waste if a change to the placement is needed. Further, once an EV battery is disassembled, you can remove gap filler and recycle it.

Bostik has designed a 2K PUR TCA specifically for heat dissipation in battery pack assemblies. Named XPU^TM  TCA 202, this 2K PUR balances thermal management with high mechanical strength while maintaining flexibility, due to its high elongation properties. It provides:

• Secure adhesion or gap filling to plastics, metals and composites; its low-monomer content helps you address the most stringent regulations without product training.
• Room-temperature cure to reduce overall energy usage. XPU^TM TCA 202 is also fast and easy to process through automatic mixing, dosing and dispensing equipment without using a primer.

Additionally, Bostik is vertically integrated to help deliver customized solutions specific to your needs, no matter where you are located.

Are you looking to enhance thermal management and other key performance levels in your EV cell-to-battery design while maintaining production efficiencies? Contact a Bostik expert to learn how 2K PUR adhesive technology can offer the capabilities you need in TCAs.

*based on internal testing

Other relevant content:

Bostik and Polytec Launch New Thermal Conductive Adhesives (TCA) Range to Accelerate Innovation in Battery Design

XPU TCA 202: 2-Part Polyurethane Thermal Conductive Adhesive

How You Can Make a More Effective EV Battery Pack

VIDEO: Thermally Conductive Adhesives for Battery Applications