Easy Fix: Solving 5 EV Battery Design and Development Challenges

The electric vehicle marketplace continues to grow, with OEMs and battery manufacturers expected to invest $860 billion in the transition to EVs by 2030, according to Atlas Public Policy. About one-fourth will be invested in the United States.

That level of investment raises the stakes for everyone involved in EV battery design and production. To keep pace, engineers are choosing pressure-sensitive adhesive (PSA) tapes as a better option than other bonding methods to address key issues in EV battery development. PSA tapes are becoming an increasingly popular choice for addressing five critical challenges faced by battery pack manufacturers.

Image used courtesy of Adobe Stock

1. Protecting Battery Parts

Battery cells can swell during charging and discharging, so manufacturers use compression foams backed with PSA tapes between the cells. These PSA tapes, designed with flame-retardant properties, help protect key components, including:

• Busbars. PSA tapes protect these flexible, printed circuits by providing electrical insulation and flame retardance—enhancing safety and reducing costs.
• Thermal Interface Materials. Thermal interface materials facilitate heat transfer between components in EV battery assemblies. PSA tapes support the cooling of battery cells and modules to ensure efficient heat transfer while maintaining optimal temperature. PSA tapes bond thermal interface materials to components such as heat sinks and chiller plates.
• Seals and Gaskets. Transfer and double-coated PSA tapes bond various gasket materials, including foams and fibers, to prevent water intrusion and unwanted noise, vibration, and harshness. They also protect battery pack enclosures from coming into contact with the chassis. Applied to seals and gaskets, PSA tapes enhance the durability of battery packs, protecting against ingress and reducing buzz, squeak, and rattle. Double-coated tapes provide another option for adding dimensional stability to gaskets and preventing them from stretching during application.

2. Preventing Thermal Runaway

Thermal runaway can occur when, at certain temperatures and voltages, the liquid electrolytes in lithium-ion batteries become volatile and start a fire. Incidents have been rare, but preventive measures are essential to protect consumers.

PSA tapes are commonly used with cylinder and pouch-cell designs due to their ability to:

• Offer flame-retardant properties when used for cell-to-cell bonding or compression padding.
• Provide secure bonding without introducing materials that could fuel an ongoing fire within the battery.
• Support diverse bonding solutions for attaching mica, ceramic fibers, aerogels, and other materials that meet manufacturer requirements for preventing thermal runaway events in battery packs.

High-performance PSA tapes, available in acrylic-, silicon- and rubber-based formulations, are commonly used to bond these surfaces as they meet UL 94 V-0 standards.

For thermal runaway applications that utilize fibrous flame-retardant materials, PSA tapes can be combined with UL 94 V-0-complaint polyester tape (single- and double-sided). The PSA tapes prevent dusting by encapsulating the fibrous material.

3. Reducing Flammability

Flame-retardant tapes and adhesives can be used for cell-to-cell bonding or compression padding without introducing materials that can fuel a fire that has already started. The acrylic-, silicon- and rubber-based adhesives referenced above can address flammability concerns plus help prevent thermal runaway. They are commonly used with single- or double-sided polyester tape. A new line of flame-retardant adhesives and filmic materials are also available that can reduce flammability in several EV battery applications while supporting thermal runaway protection.

4. Enhancing Dielectric Strength

PSA tapes provide a quick, effective way to enhance dielectric strength in EV battery packs when used for cell-to-cell bonding, compression padding, and cell-wrapping applications. There are single-sided conformable tapes that offer superior stretching properties to enhance bonding with raised and contoured surfaces. This construction limits electrical arcing due to the tape’s ability to maintain thickness and conform to sharp corners without splitting.

5. Optimizing Assembly and Design

PSA tapes offer a fast, dependable method for ensuring the structural integrity within EV battery packs. The following are the key advantages they offer:

• Ease of application. Because PSA tapes use non-reactive adhesives that are applied with pressure, they are fast and easy to adhere. In addition, when compared to liquid adhesives, they can be applied without the mixing nozzles and other equipment.
• Lightweight. Vehicle weight is a critical issue for EV production, and PSA tapes are generally lighter than mechanical fasteners. PSA tapes also provide a slim profile and continuous bond across a large surface area.
• No cure time. PSA tapes provide immediate strength, which helps streamline assembly.
• Slim profile. When used for electric insulation, PSA tapes can achieve the same dielectric strength at half the thickness of liquid coatings. That is an important space-saving benefit.

Looking Ahead

EV battery manufacturers have a choice of PSA tape constructions featuring a variety of adhesive formulations to meet their engineering, design, and manufacturing challenges. Like the batteries themselves, PSA tapes continue to evolve as tape suppliers engage with OEMs, tiers, functional material manufacturers, and converters to better understand the emerging requirements and opportunities.