Electrifying Efficiency

Global sales of electric vehicles (EVs) reached 6.6 million in 2021, marking a doubling in sales, but EVs still have a way to go before reaching the same number as internal combustion engine (ICE) vehicles. To aid in the transition to EVs, Axalta has developed coatings for insulating materials that can improve performance, sustainability, drive efficiency, and battery protection. Thorsten Heinrichs, Product Specialist for e-mobility at Axalta Coating Systems, explains how materials such as dielectric powder coatings, encapsulating resins and electrical steel coatings are critical in helping OEMs overcome challenges in EV design, while driving improvements in range, performance and efficiency.

While alternative energy vehicles are becoming increasingly popular, they are yet to surpass huge numbers on roads globally, with many consumers still harbouring doubts over range, efficiency, and even the safety of these vehicles. As such, OEMs are being challenged to not only improve their design processes and standards, but to also communicate the value of this to consumers. Extracting maximum ROI out of the lifecycle of a vehicle is critical to accelerating purchasing trends, and consumers demand that this is achieved in a sustainable manner.

One area in which improvements can be made is in motor design. Motors within EVs are expected to meet a higher set of standards and therefore must be designed with enhanced efficiency, better weather and vibration resistance, improved integration with the gearbox, and a high degree of reliability for daily usage. To meet these standards, OEMs are increasingly moving towards insulation materials, specifically designed to protect against electrical discharge, and ensure the efficient transfer of electrical energy.

PET films, paper, sheets, and tapes were traditionally used to strengthen these materials, including the prevention of electric short circuits, heat propagation and flame spread. However, application challenges with these materials remain, including adhesion limitation, air gaps and bubbles. As a result, specialist coatings are playing an increasingly important role.

Axalta provides a wide range of specialist coating solutions for these materials, designed to provide dielectric protection, maintain optimal operating temperatures, reduce the risk of fire and corrosion damage and prevent electromagnetic interference. The optimal coating depends on the position of the battery components, in addition to the manufacturing processes involved. However, dielectric powder coatings, encapsulating resins and electrical steel coatings are just a few of the solutions OEMs are turning towards to improve EV performance.

Customised coatings to support evolving EV designs

Due to the ever-evolving designs of EVs, it is important that any dielectric powder coating remains customisable to the application. One example is battery enclosures. While these often employ a coating solution, they are also designed with protrusions on the surface. These serve several purposes, such as providing additional support and structure, or protecting the battery from damage during use. However, due to the sharp rises of these protrusions, electrical insulation failure is not uncommon. That’s why Axalta has worked with customers to develop unique dielectric powder coatings which can be modified to allow special coverage of the bumps and therefore address these electrical insulation challenges.

Protecting the battery is one requirement, helping to extract more efficiency from it is another. If EV adoption is ever to reach various government targets in the next few years, OEMs will have to help consumers overcome range anxiety, which is where electrical steel coatings play a critical role. 

Improving the electrical insulation of the electric drive itself can significantly improve overall vehicle efficiency. For example, reducing the occurrence of eddy currents can reduce energy losses and improve efficiency of the system. Eddy currents can be generated in the metal components of a motor and other electrical equipment when the magnetic field changes rapidly, such as high driving speeds, in the case of an EV. These eddy currents can cause energy losses and heat build-up, reducing the efficiency of the system and potentially damaging internal components.

Electrical steel coatings therefore must be specifically formulated to provide superior electrical insulation to the drive, corrosion resistance, and adhesion to electrical steel laminations. It is critical that these coatings help to improve the performance and reliability of electrical equipment by reducing the risk of electrical shorts, reducing core losses, and improving the durability of the laminations.

A lifecycle approach to sustainability

While the transition towards EVs is an environmental one, it is important that OEMs don’t just consider their sustainability impact by measuring tailpipe emissions alone; switched on consumers are increasingly expecting more.

Imagine you have an electric drive for a vehicle and the insulating materials and coatings make it more efficient because they conduct the heat out of the motor faster than another resin. However, all of these gains are cancelled out if the materials you used for the coatings are packed full of volatile organic compounds (VOCs).  That’s why concerted efforts have been made to reduce VOC emissions in car manufacturing to improve air quality and reduce potential health risks during manufacture.

Another area in which OEMs can make important strides is through the use of renewable materials.

The content of renewable raw materials in Axalta’s impregnating resins and casting resins (encapsulation resins) starts from around eight percent today and reaches almost 60 percent. One of its most popular impregnating resins for battery powered cars — Voltatex® 4200, contains about 10% raw materials based on renewable resources. Another of Axalta’s encapsulation resin products has almost 60 percent renewables. 

OEMs should consider emissions and carbon consumption throughout the entire lifecycle of a vehicle to find ways to reduce their environmental impact. This can include improving design, materials selection, and manufacturing processes to use resources more efficiently, reduce waste, and comply with regulations. Using low carbon, low VOC coatings in insulating materials can help meet these goals and improve brand reputation for environmental responsibility while enhancing overall vehicle performance – all of which are crucial to capturing consumer demand.