It has been two years since the last article update on polymers in electric vehicles. Andy Pye reviews the trends and reflects on some future projections.
According to a report issued in 2023 by the American Chemistry Council (ACC), on average, plastics make up less than 10% of a vehicle’s weight yet account for approximately 50% of its volume. It is perhaps surprising that, despite one of the main drivers behind increased use of plastics, vehicle weight continues to trend upwards, reaching around 1950kg in 2021, according to Environmental Protection Agency (EPA) data. This is an increase of around 16% compared to a decade earlier. Why is this? Firstly, passenger cars and light trucks are getting larger, and they are being crammed with more and more features: they are being fitted with all manner of sensors and infotainment systems, meaning that even smaller vehicles are tending to bulk up.
A car’s electrical system used to be limited to a few components, but today’s vehicles rely on electrical components for myriad functions. Less than two decades ago, dashboards were crammed with heavy copper wiring. But advances in acrylic fiber optic cables have eliminated the need for copper. This means enhanced illumination of the interior, more accurate GPS data, and highly responsive ABS sensors. Plastics are also used in switches and sockets, connectors, and wiring.
Additionally, light-duty trucks accounted for 55% of vehicle sales in the United States in 2021, up from 36% in 2012. And since larger vehicles generally use more fuel or electric charge, consumers tend to purchase smaller vehicles when average gas prices are high. An interesting parameter that is being increasingly cited is the “chemistry value per vehicle”, which includes not only plastics of all types, but also semiconductors and other electronics, textiles, fluids and lubricants. Over the past decade this has grown by around 20%.
According to The Boston Consulting Group, by 2030 electrified propulsion will approach, and perhaps surpass, the internal combustion engine in global market share. As we move to electric vehicles (EVs), the propulsion system and infrastructure also adds a significant weight penalty. EV batteries are significantly heavier than internal combustion engines, driving manufacturers to incorporate more plastic into more components like the chassis and battery casings, to partially offset that additional battery weight, a technique known as “compensatory lightweighting”. Compared to metal assemblies, large-format all-plastic housings enable cycle time reductions and contribute to lighter vehicle weight, thus extending the range of electric vehicles.
EVs have different cooling requirements than internal combustion engines, which may render certain types of vehicle grilles and front fascia obsolete, thereby creating opportunities for new advanced plastics-based front-end vehicle designs.
Though best known as insulators, plastics can be made conductive, hybrid engines might consolidate parts and reduce weight further. And more EVs means more EV chargers, which also require plastics to manufacture and function. According to the latest report by Reports and Data, the global electric vehicle polymers market size of $6.91 billion in 2020 is expected to reach $418.27 billion in 2028, a revenue CAGR of 66.9%.
Temperature-resistant polymers
Temperature resistant and thermally conductive plastics are well suited to heat-sensitive applications, including electric vehicle battery parts and enclosures. Moving from internal combustion engines to batteries opens up new opportunities for polymers. Operating temperatures are much reduced, but flame retardancy remains critical. Engineering polymers are available with flame retardancy, electric isolation, thermal conductivity and cooling compatibility.
In January 2024, Freudenberg Sealing Technologies based in Weinheim, Germany, announced a new class of materials, for improving fire protection in electric vehicle drives. Quantix ULTRA resists melting even at extreme temperatures of up to 1,200C. The first series application is now underway, as a flame protection barrier for cooling system parts in an electric car’s lithium-ion battery.
Various safety measures are being implemented to make sure that any thermal runaway of an EV battery is prevented or delayed. So far, plastic components used for this purpose have generally failed to meet the automotive industry’s strict test standards. The new material does not melt or ignite; in laboratory tests, a 2mm-thick material sample can resist an applied flame with a temperature of 1,200C for over 25 minutes. Further tests simulate the emission of hot particles under high pressure, which can occur if the gases in battery cells are abruptly discharged. Quantix ULTRA withstands the stress test for 20s. A 2mm-thick material aluminium sample only takes 2-3s to be destroyed.
The base material of Quantix ULTRA is a thermoplastic that is already temperature resistant. The precise addition of fillers such as glass or carbon fibres reinforces the mechanical stability even under enormous heat. The additional cross-linking of the plastic molecular chains ensures that the component maintains its shape even under extreme conditions. The material properties can be adjusted with a focus on the specific application. “Our patented know-how consists of the precise addition of suitable materials that create bridges between the molecular chains. The patents are the result of successful teamwork,” explains Dr. Björn Hellbach, Material Expert Thermoplastics at Freudenberg Sealing Technologies.
Processing the material in injection moulding is both versatile and economical. The material can also be processed into films. Other potential applications include enclosures for power supply units, media-carrying lines, cable insulation, battery housing covers and components for electric motors.
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Resource shortages?
Several raw materials are considered critical for producing EV batteries, including lithium, nickel, neodymium, dysprosium, copper and two forms of graphite. Though none of these are polymeric, supply challenges may influence the long-term viability of batteries, both in terms of the amount of the materials required and the geopolitics of sourcing them.
China produces around four-fifths of the world’s rare-earth supply, mostly in Inner Mongolia, although it has only 37% of reserves. Australia is second and the only other major producer, with 15% of world production.
With 8 million tonnes, Chile has the world’s largest known lithium reserves, while Australia has 2.7 million tonnes, Argentina 2 million tonnes and China (1 million tonnes).
Against that, technological advancements over the next decade will cut by half the amount of lithium required to make an EV battery. The amount of cobalt required will drop by more than three-quarters and nickel by around a fifth.
The recent spike in the price of PVDF has been almost entirely a result of the copious amount of this polymer needed to manufacture EV batteries. It is estimated that each EV battery requires about 6.5kg of PVDF, used both as an electrode binder and as a coating material for the battery separators.
Plastic waste to fuel hydrogen cars?
At present, hydrogen-fuelled vehicles are more of a niche market than battery-powered vehicles. But if raw material supply issues become more concerning, then hydrogen vehicles could become more predominant. There would then be a complete change in the polymer materials which predominate. This is covered in the previous article (Ref 3).
Hydrogen fuel cell vehicles are powered by electric motors, but instead of carrying their energy in a battery pack, they create electricity by combining hydrogen with oxygen from the air in a fuel cell. Water vapour and heat are the only by-products.
One downside is that hydrogen fuelling stations are few and far between; in the United Kingdom there are fewer than 20. Yet some countries are forging ahead with the technology: Japan aims to have 200,000 hydrogen cars on its roads by 2025, served by 320 fuelling stations.
About three quarters of the world’s hydrogen supplies are made from natural gas, a process that produces carbon emissions. But even cars powered this way can reduce carbon emissions by more than 30% compared with conventional vehicles, according to US non-profit Union of Concerned Scientists.
UK company Powerhouse Energy wants to turn the current plastic deluge into an opportunity by producing energy from non-recyclable plastics and other waste. Britain produces about 5 million tonnes of plastic waste every year, but less than a third of that is recycled.
Powerhouse Energy has developed a process where it shreds the waste and then heats it to around 1,800F to produce Syngas, a mixture of hydrogen, methane and carbon monoxide. Syngas can either be burned to produce electricity, or the hydrogen can be separated out to power fuel cells in vehicles.
“For road transport, hydrogen is the perfect fuel,” says David Ryan, CEO of Powerhouse Energy. “For large trucks and buses, it is probably the future of clean fuel, because its emission is water.”
Powerhouse Energy says its own production process emits much less CO2 than using natural gas, giving motorists a significantly greater emissions saving ࢀ” while using up rubbish that would otherwise go to landfill.
Powerhouse Energy’s process is still at demonstration level, but it plans to soon expand to 11 sites in the United Kingdom. It ultimately hopes to have a number of small facilities near cities worldwide, using local waste to provide communities with power and hydrogen. Locating a plant at or close to a hydrogen cell refuelling point would reduce the carbon emissions created by transporting the hydrogen.
“The vision is that fuel-cell vehicles can be used in the place of hybrids now ࢀ” so you might have a fuel-cell car with a battery backup,” says Ryan. “But for lorries and buses, the vision is that they could be totally hydrogen fuelled. We can provide enough fuel for a day’s transportation and then they return to base to refuel for the next day.”
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Sustainability
Sustainability in the design and development in polymer components will be considered in an article scheduled for next month, both with reference to the automotive industry and elsewhere.
References
- Chemistry and Automobiles, March 2023. American Chemistry Council
https://plasticmakers.org/wp-content/uploads/2023/02/Chemistry-and-Automobiles-March-2023.pdf - Report: More Plastics Used in Automobiles, Improving Fuel Efficiency, Safety and Performance
https://www.americanchemistry.com/chemistry-in-america/news-trends/press-release/2023/report-more-plastics-used-in-automobiles-improving-fuel-efficiency-safety-and-performance - Polymers for Electric Vehicles (EV)
https://www.ulprospector.com/knowledge/12939/pe-polymers-for-electric-vehicles-ev/ - Freudenberg Develops Extremely Temperature-Resistant Plastics for Electric Cars
https://www.fst.com/news-stories/press-releases/2024/thermoplastics-for-up-to-1200-degrees-celsius/#:~:text=By%20offering%20a%20new%20class,up%20to%201%2C200%20degrees%20Celsius.
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