Heat, and the most effective ways of controlling it, should be top of mind for electric vehicle (EV) manufacturers. Thermal management is crucial to how EVs perform. Without it, the vehicle’s battery may experience accelerated degradation, or worse, it can unexpectedly catch fire.
Thermal management is crucial to how a Li-ion battery performs, especially when used in the design and manufacturing of EVs.
Choosing specialized materials — specifically thermal interface materials — can help optimize the efficiency and lifespan of EV batteries and the vehicle’s power conversion systems. The ideal materials provide optimal heat management and regulatory compliance, ensuring safety.
A safer battery
EVs predominantly use lithium-ion (Li-ion) batteries as their power source. During charging and discharging, Li-ion batteries are a significant heat source. Handling that heat safely and effectively is critical for safety.
As the battery is the heaviest and most costly component in an EV, repairing and replacing it is not a trivial endeavor. Substantial heat is a by-product of the battery’s charging and discharging cycles, which can damage EV battery circuits and connection points, shorten range, and ultimately shorten service life.
The latest thermal adhesives and gap fillers help transfer heat away from batteries, increasing overall battery life while helping manufacturers scale and minimize operating and warranty costs. They provide ample heat dissipation, with thermal conductivity levels of 1 to 7 Watts per meter Kelvin (W/m-K).
The geometric shape of EV batteries is also an important engineering choice to support power density and more effective design. Batteries are typically cylindrical or rectangular), but vehicles are not. As a result, maximizing the battery size to fit a confined space is necessary while designing an aesthetically pleasing vehicle, which presents complex design challenges.
Custom-tailored gap fillers can provide auto manufacturers with additional flexibility to ideally match various battery and car shapes and sizes when creating cell-to-pack or cell-to-chassis designs. Gap fillers are suitable for mass production due to their high dispense rates, excellent control, and fast application times.
Gap fillers are thermally conductive gap filling liquid materials designed to enhance thermal performance.
Regulatory requirements
EV battery manufacturers face several challenges, including complying with stringent regulatory requirements for fire protection. Advanced materials, such as epoxy fire-protection coatings and flame-retardant foams, enable safer and more compliant manufacturing.
Thermal propagation prevention (TPP) solutions can safeguard EV operation and, most importantly, the vehicle’s occupants. Two-component epoxy technology can be applied to the inside or outside of a battery lid to create a thermal insulating layer that can provide fire resistance of up to 1,100º C for up to ten minutes. The cavities between cells in battery packs can also be filled with liquid-applied 2K (two components) rigid foam to increase flame-retardant properties and block cell-to-cell heat transfer.
Power conversion systems
As manufacturers work to improve EV range, power conversion components must endure increased stress. There are three main power conversion systems in EVs: onboard chargers, ac/dc inverters, and dc/dc converters.
By micro-sizing these power electronics and integrating them with other EV power systems, manufacturers realize gained space. However, they can also become a challenge. Miniaturized electronics face a range of technical challenges that are exacerbated due to their micro size.
By micro-sizing these power electronics and integrating them with other EV power systems, manufacturers gain space. However, this can also lead to challenges. Miniaturized electronics face a range of technical challenges that are exacerbated due to their micro size.
For example:
1. The first significant challenge is thermal management. As the electronics shrink in size, so does the component footprint, reducing the available surface area that dissipates heat. This is a crucial challenge as EVs are engineered for fast charging, and effective heat dissipation is vital to maintain safe operating conditions.
Designed for applications such as bonding battery cells to modules, or bonding cells directly to cooling systems, Loctite TLB 9300 APSi is an injectable thermally conductive adhesive for EV battery systems.
Thermal interface materials enable just that. Solutions such as gap fillers, gap pads, and thermally conductive adhesives are core to battery thermal management and are designed to meet EV requirements of higher power density and greater power efficiency.
2. The second challenge is for the power components to withstand the ongoing mechanical strain and harsh conditions inherent in vehicle operation. Advanced materials can bolster shock, vibration, chemical, and environmental resistance.
Solutions include a broad range of gasketing technologies that provide sealing capabilities while improving the reliability and durability of power electronic components.
3. The third challenge is to reduce material and processing costs. Manufacturers are seeking productivity gains through shorter cycle times and automated production. Automation-friendly materials can help. Manufacturers can save energy costs with room-temperature curing solutions and reduce labor costs via more efficient automation.
A lighter body
The vehicle body is central to safety. Because EV batteries are so heavy, the rest of the vehicle must help compensate and be as lightweight as possible. However, reducing weight in vehicle bodies can also compromise crash safety.
Material advances have achieved a skillful balance that enables vehicle lightweighting while meeting or exceeding performance requirements. Such material designs are made during early EV development stages. They can be accomplished in several ways, including using lightweight metal, downgauging existing metal, or redesigning architecture to remove existing components altogether.
In one example, aluminum used for a rocker reinforcement was replaced with a structural foam insert. The result? The new solution saved weight, maintained strength, and met performance specifications.
Final thoughts
Safety must be prioritized in electric vehicle design and operation. Throughout the EV, advanced polymers materials can be used in several innovative ways to ensure vehicle safety and better protect drivers. For example, thermal interface materials — such as gap pads, fillers, and conductive coatings — can help dissipate EV battery heat. Dual-purpose materials also hold the battery securely in place and conduct heat away for a safer vehicle.
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Filed Under: Adhesives, FAQs