How powder coatings support the safety & performance of EVs

June 24, 2024

Powder coatings support the safety & performance of EV batteries & systems

Yidong Meng

Since the wheels of the first electric vehicle started rolling more than a century ago, development has been slow, and painfully so. It wasn’t really until the launch of the Nissan Leaf in 2010 that an affordable EV became available to a wider audience. More recently, there has been significant progress. In 2022, EV sales exceeded ten million, with 14% of all new cars sold being electric (up from 9% in 2021 and less than 5% in 2020). While final figures are yet to be analysed, it’s predicted that EV sales in 2023 reached 14 million or 18% of total car sales. (Source: Virta Global.)

All of the big automotive manufacturers are rolling out hybrid and pure electric vehicles as they plan the transition away from the traditional combustion engine. Widely published concerns regarding the vehicles’ range, cost and value for money are steadily being addressed as the rise in popularity of electric vehicles is being driven by increased accessibility as new, more affordable models are launched onto the market.

Government and regional policies within individual countries are playing an important role in accelerating EV adoption and manufacturers are gearing up accordingly. Globally, Toyota is seeking 1.5 million battery electric vehicle (BEV) sales by 2026 with plans to introduce ten new models; Mazda predicts at least 25% of all global sales will be BEV by 2030, while Honda also plans to launch 30 new EV models by the end of the decade. In Europe, Ford has a target of 600,000 BEV sales by 2026; VW is switching to full electric production by 2033; and Porsche is aiming for 80% of all sales to be electric by 2030. (Source: Virta Global.)

car black angle powder

Common challenges regarding safety and performance

Regardless of who’s currently leading the charge to an all-electric future, manufacturers around the globe face a set of common challenges. Perhaps the biggest one is safety, and one of their most effective weapons in reducing risk is their choice of coatings for the battery and the motor.

Global regulations on passenger safety are becoming increasingly demanding, and rightly so. EV fires are uncommon, but not unheard of. Whereas the incidence of EV fires per mile travelled is far lower than ‘conventional’ vehicles, avoiding fires is a top priority and understanding where the risks are coming from is key. (Source: Forbes.)

Thermal runaways occur as a result of one of several factors: an internal short circuit; an external short circuit; overcharging the battery beyond its maximum voltage; or excessive currents, when charging or discharging the battery. Maintaining the mechanical and thermal stability of the battery has to be guaranteed, and one way of maintaining such stability is the use of powder coatings.

While powder coatings can insulate the battery directly, they can also play a key role in protecting the vehicle’s cooling systems by electrically isolating and protecting its components and helping to keep the battery within its optimal temperature range.

Helping to prevent extremes of hot or cold is not just about risk; it’s also about performance. If the temperature’s too low, the battery’s power is decreased, reducing capacity and – ultimately – vehicle range. If the temperature’s too high, the battery degrades at an accelerated pace. Powder coatings also support the longer-term performance of the battery by protecting it against corrosion and other threats.

Beyond the battery and the cooling system, powder coatings protect the wider electric ecosystem of the vehicle – its hairpin stators, busbars, battery cell and other components – many of which have long-term heat resistance requirements. EV charging points generate considerable heat; fast chargers can push battery pack temperatures to 270ºC after just a few minutes of charging, so being able to protect the battery and vehicle components from such extremes supports the longevity of the vehicle and its operational safety.

Powder coatings have a high heat emission rate (i.e. ‘thermal emissivity’), which means they can help to control radiative heat transfer by tailoring surface emissivity (like bus bars). Radiative heat transfer is mainly an issue at higher temperatures where conventional thermal insulation methods aren’t sufficient.

Supporting a sustainable manufacturing process

The other big challenge that all manufacturers of electric vehicles face, and which powder coatings can support, is the need for their own manufacturing processes to be sustainable.

The automotive industry has many significant environmental regulations and directives with which they must comply: these include, but are by no means restricted to, the EU Directive that determines the removal of certain metals, chemicals and elements within the manufacturing process, including lead, mercury, and hexavalent chromium; REACH which determines the registration, evaluation, authorization and restriction of chemicals; and GADSL which compiles a global automotive declarable substance list. There’s also a database for information on substances of concern used in products (SCIP) and rules on the treatment of waste from electrical and electronic equipment (WEEE).

The use of powder coatings supports manufacturers with all such regulations and directives. Being free of volatile organic compounds (VOCs), they protect the environment and also people, creating minimal waste, and enabling powder that has been over-sprayed to be re-claimed and re-used. The durability afforded by a powder coating also enables the surfaces it’s protecting to last for longer, extending a product’s lifetime and performance.

Powder coatings deliver a stable, consistent, longer-lasting performance, even in challenging environments, providing a right-first-time finish and high edge coverage. They can also be applied quickly and easily, requiring fewer stages in the application process, therefore consuming less energy, improving efficiency and reducing costs.

Consistent performance

Being certain of a powder coating’s performance is, of course, essential. Resicoat powder coatings from AkzoNobel, for example, have been tried and tested over more than 50 years.

Each of the five product ranges developed within the Resicoat EV range has been specifically innovated to enhance the safety and performance of the EVs of tomorrow. They have superior electrical insulating properties and enhanced thermal management to help protect the battery systems, motors and electrical storage units.

The range comprises Resicoat EVpack which delivers a range of protective properties for the battery pack or housing to insulate electrical systems; Resicoat EVcell which provides outstanding cell-to-cell electrical insulation for even the most intricate designs; and Resicoat EVcooling, designed to deliver superior performance in thermal conductivity,electrical insulation, edge coverage and consistent film building in cooling tube and cooling plate applications.

battery black angle powder

It also includes Resicoat EVbusbar to coat the busbars that carry and distribute electricity to improve heat dissipation and support a lower fire load with a longer lifetime during thermal impact. To protect the electric motor, the Resicoat EVmotor range includes epoxy powder solutions that are specifically designed for the electrical insulation of hairpin stators.

Key solutions within the Resicoat EV range are tested and approved to UL 94 V-0 which enables vehicle systems to tolerate a certain amount of exposure to a flame without igniting. They’re also tested and approved to UL746B and UL1446, ensuring they can resist thermal degradation and possible damage that can occur at elevated temperatures.

Powder coatings are available and proven and new innovations continually being developed that go further in enhancing thermal management systems and superior electrical insulation to help power the next generation and allow electrical components to perform in extreme environments. Powder coatings are being innovated not just for the here and now, but also to support the ultra-light automotive platforms of the future.

Yidong Meng, Global EV and Functional Segment Manager, AkzoNobel Powder Coatings

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