By Joanne Moody, Zeta Scientific LLC, Livermore, CA
Electric vehicle (EV) production is growing exponentially to meet increasing stringent carbon dioxide emission standards. EVs run on electric motors that require a constant supply of energy from batteries, which are disrupting the auto industry. This article focuses on three areas where adhesives contribute to improving EVs: (1) Environmental Protection, (2) Thermal Management, and (3) Weight Reduction.
Hidden under the hood and throughout the car body are adhesives, sealants, and coatings, enabling technologies. These materials help batteries perform and meet various requirements, including securement, environmental protection, thermal management, and safety. Types of adhesives to meet these challenging requirements include epoxies, polyurethanes, acrylics, silicones, sealants, thermoplastics, and foam tapes.
1. Environmental Protection
Vehicles experience a range of environments, including high humidity, extreme temperatures, automotive fluids, dirt, vibration, and mechanical forces during vehicle operation. The EV batteries must be well-secured to withstand these harsh conditions. Adhesives, sealants, coatings, and foams bond dissimilar materials such as plastics, metals, glass, and composites. See Figure 1 from Greg Moran article “Adhesives in Automotive Assembly”
Figure 1 – EV Adhesive Applications
Source: Adhesives & Sealants Industry
2. Thermal Management
Batteries generate heat during operation, which makes thermal management critical to the battery design and assembly. Cooling systems mitigate heat, and along with adhesives, gap fillers, and coatings that can be thermally conductive, insulative, or electrically conductive, and prevent short-circuiting, thermal runaway, or degradation. The bonds should have sufficient flexibility for the expansion/contraction of the battery cells during usage. Adhesives as gap fillers protect the battery cells. Thermal material formulations and applications prevent, retard, or stop fires if the battery is damaged or overheated. See Figure 2 for a battery pack example.
Figure 2 – EV Battery Pack Example
Image source: https://www.123rf.com/profile_daseaford
3. Light Weighting
Current EV batteries contribute about 25% of the total EV weight and thus work against battery life. Weight reduction, or “Light Weighting” of the EV, improves battery performance and time between charging. Adhesives lighten weight by replacing traditional mechanical fasteners to fit the tight tolerances of EV battery design. Structural adhesives can also absorb flexion on the frame, which reduces potential damage to the battery in the event of excessive vibration or a crash.
Challenges
EVs face growing challenges in weight reduction, battery life, environmental protection, safety. Adhesives and sealants do, however, have one negative feature: they can make the battery packs “non-serviceable, requiring replacement of the entire battery unit. The ability to “De-bond” the service packs can be improved with design and materials selection (such as using a cover, removable sealants, or gaskets). Recycling both the battery and adhesives remains an environmental challenge.
Summary
With the exponential growth of battery-operated devices and EVs, adhesives provide environmental protection, battery thermal management, and light weighting. Integration of adhesives, sealants, and materials science technologies will help develop more reliable and lower cost EVs.
Additional Resources
About the Author
Joanne Moody, the Principal Consultant at Zeta Scientific LLC, specializes in solving complex, real-world challenges involving adhesives, coatings, plastics, and materials science. Clients are startups to international corporations. Industry experience includes medical devices, consumer products, electronics, transportation, food, chemical, and water filtration.
