Business Development Manager – E-mobility and Automotive
Avery Dennison Performance Tapes North America
In the electric-vehicle (EV) battery industry, pressure-sensitive adhesive (PSA) tapes are becoming increasingly popular as a multi-functional technology with several applications. From enhancing battery efficiency and ensuring safety to optimizing production, these tapes address some of the most critical challenges faced by battery-pack manufacturers today.
PSAs are non-reactive adhesives that stick with pressure, making them easy to use. These tapes offer a quick and reliable way to provide structural integrity in an EV battery pack.
PSA tapes offer convenient assembly, a slim profile, and a continuous bond across a large surface area. They’re generally lighter than mechanical fastening systems — important in an industry focused on reducing overall vehicle weight.
PSA materials bond with no cure time and provide immediate strength, which can act as an assembly aid. They also eliminate the need for mixing nozzles or other equipment required by liquid coatings.
When used for electric insulation, PSA tapes offer space-saving advantages compared to other bonding techniques. Liquid coatings, for example, typically require a thickness of at least 150 microns. PSA tapes can achieve the same level of dielectric strength at half the thickness.
What’s more: PSA tapes can help manufacturers qualify for incentives included in the Inflation Reduction Act. Starting in 2024, 50% of the components used in EV batteries must be produced or manufactured in the U.S., or one of 20 countries with a free-trade agreement with the U.S., to qualify for consumer incentives.
Protecting battery parts
Pressure-sensitive adhesive tapes are increasingly used by engineers and designers to bond battery cells together and compression pads to cells and modules.
Compression pads protect battery cells that can swell during charging and discharging. To prevent damage, EV battery manufacturers place compression foams backed with PSA tapes between each cell. These tapes are also designed with flame-retardant properties that protect batteries against fires.
- Busbars are printed circuits that offer cost-saving flexibility and safety features in EV battery applications. PSA tapes protect these flexible, printed circuits by providing electrical insulation and flame retardance.
- Thermal interface materials (TIMs) facilitate heat transfer between components in EV battery assemblies. PSA tapes securely bond TIMs, such as thermal pads or films, to components like a heat sink or chiller plate materials. This assists with battery cell or module cooling, ensuring an efficient heat transfer while maintaining optimal battery temperature.
- Sealing and gasketing are critical for preventing water intrusion and unwanted noise, vibration, and harshness while protecting battery pack enclosures from contact with the chassis. Transfer and double-coated PSA tapes bond various gasket materials, including foams and fibers.
PSA tapes enhance battery pack durability, provide protection against ingress, and reduce buzz, squeak, and rattle. They’re a thin and instant bonding solution for gasket materials. Double-coated tapes are another option, adding dimensional stability to gaskets and preventing them from stretching during application.
PSA tapes also bond flexible printed circuit heater films to keep cells warm in the pack. This prevents battery issues related to low temperatures, including underperformance and potential damage during charging. Various temperature-resistant tapes are available that maintain durability even after multiple heating cycles. Additionally, there are low-ooze options that optimize die-cut and precision-processing purposes.
Providing insulation and strength
Electrical insulation and cell wrapping are critical to protect batteries from damage, preventing the risk of electric failures and improving battery life. Protective layers around individual battery cells ensure the electric insulation the cells require to function effectively.
Single and double-coated PSA tapes, which feature dielectric films, can either be applied to these layers directly or on foam compress pads for adequate electrical insulation in EV batteries. These tapes offer flame-retardant properties with dual dielectric and flame protection. They’re also versatile and can be applied to various surfaces, including rigid materials such as aluminum chill plates and other metal structures.
PSA tapes offer a durable solution to enhance the dielectric strength of EV battery packs when used for cell-to-cell bonding, compression padding, and cell wrapping applications.
A recent advancement in this area is the introduction of conformable dielectric tapes. This single-sided conformable tape feature, designed specifically for EV batteries, provides enhanced stretching properties — allowing for better bonding with contoured and raised surfaces. The conformable face stock also prevents electrical arcing. The tape uniformly maintains its thickness and conforms to sharp corners without splitting.
The adhesive industry has grown significantly by actively engaging with OEMs, tier suppliers, and converters to gain insights into their engineering challenges and design requirements. EV manufacturers choosing PSA tapes have an extensive range of adhesive chemistries and tape constructions available to tailor solutions to the application.
Battery safety and thermal runaway protection
Electric-vehicle battery designers incorporate thermal runaway protection in batteries at multiple levels, including the cell and pack. Engineers and designers are relying more on PSA tapes as a bonding solution for thermal runaway applications for several reasons, including:
- Compatibility in cylinder and pouch cell battery designs that are common in North America
- Flame retardant properties when applied for cell-to-cell bonding or compression padding
- Ability to provide secure bonding without introducing materials that could fuel an ongoing fire within the battery
- Diverse bonding solutions for attaching mica, ceramic fibers, aerogels, and other materials that are crucial for safeguarding cells and passengers, meeting manufacturer requirements for preventing thermal runaway events in battery packs
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.
Acrylic, rubber, and silicone-based adhesives have been developed that meet UL 94 V-0 standards and other flame requirements. These adhesives are paired with polyester tape in single or double-sided constructions for EV batteries.