Protecting BEVS

How coatings and surface solutions are advancing the development of battery electric vehicles.

The chances are, for most of your driving history you have operated a vehicle with an internal combustion engine (ICE) drivetrain. However, the electric vehicle (EV) revolution has arrived.

Automotive manufacturers are investing billions of dollars in new, fully electric models mostly powered by lithium-ion batteries. This revolutionary drivetrain change is accompanied by evolutionary changes throughout these vehicles: The integration of new functionality, features, materials, styling and even design and construction approaches is accelerating. This historic shift represents a tremendous opportunity for businesses at every level. It also presents profound challenges, many of which can be best addressed with coatings and surface solutions.

Getting specific

Coatings and surface solutions are critical to the protection and beautification of the EV interior, exterior and underbody parts, sealing the vehicle from outside elements and joining a multitude of parts. Inside and out, EVs must look great, feel great and last. While the coatings to achieve this are similar to those used for ICE vehicles, many are necessarily tailored to the specific needs of the EV: Differentiated innovative automotive coatings with a laser focus on productivity and sustainability benefits for the customer.

The electric drivetrain and especially the EV battery pack presents a plethora of new surface and interface challenges related to system safety, performance, durability and cost. Advanced coating technologies can provide efficient, effective, scalable solutions that help EV and battery manufacturers accelerate the development of tomorrow’s passenger and commercial vehicles.

Battery pack challenges

EV battery packs present some familiar challenges addressed by the automotive industry with coatings and surface solutions: pack components must be protected against corrosion and impact, bonded, and sealed from outside elements. Electrodeposition and powder coatings, adhesives, and sealants address these needs, extending service life. The battery pack, including the battery management system (BMS) – the electronic “brain” of the system – must be protected from electromagnetic interference (EMI) or “crosstalk” with other safety and performance-critical electronics in the vehicle. This is accomplished with EMI shielding, including using thin conductive coatings that conform to the electronics enclosures.

EV battery packs also present new, unfamiliar challenges for the automotive industry. Specifically, dielectric isolation, thermal management, and fire protection are essential for safety, performance and lifetime. EV batteries operate at high voltages, and components must be electrically isolated. Battery cells have a narrow thermal operating window that must be tightly maintained. Control system malfunctions, manufacturing defects, overheating or heat exposure, or damage from collision can result in thermal runaway events with intense and energetic fires.

These challenges are heightened by the race to push the performance limits of the battery packs. Increasing EV range per charge and decreasing charging time are key to overcoming barriers to adoption. This has led to higher operating voltages, the development of higher energy battery active materials with increasing temperature sensitivity, and higher-capacity cell and pack formats. As EV designers and manufacturers work to decrease charging times, waste heat fluxes during charging will be higher. A battery is most likely to experience a hazardous malfunction when it is at a high state of charge and when it is overheated. The importance of effective dielectric isolation, thermal management and fire protection is growing with current battery design trends.

Overcoming the challenges

These most critical new industry challenges can be effectively addressed with advanced coatings and surface solutions. Coatings can be designed to be multifunctional, addressing several challenges simultaneously, while reducing manufacturing complexity, weight and cost.

Dielectric isolation coatings can provide corrosion protection while enhancing thermal management and enabling enhanced bonding. Corrosion coatings, adhesives and sealants can include fire mitigation functionality. Fire mitigation coating systems can include shielding to address EMI of configured to provide dielectric isolation. These multifunctional coatings are conformal and can be applied seamlessly to complex three-dimensional shapes and adapted quickly to different platforms or changing designs.

Lastly, battery EVs must be manufactured on an assembly line to maximise output. Coatings have been applied in an assembly line process for decades and provide reliable, high-volume, automated production of battery cells, modules and packs which reduce operating costs by increasing manufacturing output.

Standards and testing

As the number of EVs continues to increase, globally harmonised manufacturing standards and unified testing protocols must be developed to minimise risks associated with the high amount of energy on board. Currently, EV manufacturers are at very different maturity levels regarding standards, critical requirements, and specification and test capability against which to measure safety solutions.

Coatings providers with an advanced understanding of industry standards and the capability to test and qualify materials can facilitate and accelerate identification and approval of protective materials. The evolving EV market will favour the simplest and lowest total cost option and manufacturers and consumers will both benefit from clearly defined safety requirements.

Calum Munro is a Senior Scientist, Mobility at PPG