Electric vehicles function by plugging into a charge point and taking electricity from the grid. There are two main technologies: rechargeable lithium-ion batteries (currently favored) and hydrogen fuel cells.
Battery-powered vehicles
Here, electricity is stored in rechargeable batteries that power the motor. With recycling, a battery-powered electric vehicle (EV) uses up just 30kg of raw materials, compared to the 17,000 liters of petrol burned by the average car.
However, several raw materials are considered critical for producing these batteries, including lithium, nickel, neodymium, dysprosium, copper and two forms of graphite.
Though none of these are polymeric, supply challenges with some of the above may influence the long-term viability of batteries, both in terms of the amount of the materials required and sourcing them, given the current geopolitical situation.
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 tons, Chile has the world’s largest known lithium reserves, while Australia has 2.7 million tons, Argentina 2 million tons and China (1 million tons).
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.
Despite this, 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%.
This is due to new opportunities in the electric drivetrain, and the increasing volumes of units. Increased polymer content reduces weight without affecting the efficiency of the car.
Polymer content
Over 70% of the plastic used in automobiles comes from four main polymers: polyamides, polypropylene, polyurethane, and PVC. Engineering thermoplastics designed to withstand the high heat and electrical currents generated by electric vehicles are also attractive. Polymers such as PEEK, PTFE, PEI and PI have exhibited tremendous resistance to heat, such that there seems little argument for using metals (which would be at least two to three times heavier) in areas where these polymers can be used.
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.
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.
Charging infrastructure is another area where components for eMobility must exhibit excellent mechanical performance at elevated temperatures and high dimensional stability. They must endure demanding conditions while offering safety and long-lasting durability for color, surface finish and UV stability.
Where electricity flows, connectors and cables will be needed and the plastics used have to show electrical insulation, flame retardancy and hydrolysis resistance. An electric vehicle depends on the efficiency of the battery and the use of stored power. Anything that helps minimize the leakage of current from the system aids in improving the battery life and consequently the distance that can be traversed on a single charge. Materials like PTFE and Polyimide have proven highly effective as insulators in high-voltage-high-temperature applications.
The use of sensors is essential in ensuring safety. As autonomous vehicles see a rise in adoption, sensors will become possibly the single most important component set within a vehicle. Polymer shields and connectors are important because, unlike metals, they remain neutral to the signals and waves being sent and received by the sensors. PTFE and PEEK are already used extensively as radomes in antennae. Polymers are unique in being able to offer protection from weather, heat, and additionally do not interfere in any way with the signals.
The proliferation of vehicle battery systems with higher energy densities creates a greater need for increased occupant protection from fire hazards. Flame-retardant polymers, including adhesives and fabrics, could help reduce the risk of fires from spreading.
Advanced polymer-based battery pack protection separators used in lithium-ion batteries can ensure temperature stability and extend range. Both PTFE and PE (polyethylene) are seen as effective battery separators.
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.
Hydrogen vehicles
At present, hydrogen-fuelled vehicles are more of a niche market than battery-powered vehicles. On the way to the ultimate eco-car, as Toyota puts it on its website, the public focus in recent years was on hybrids, plug-in hybrids and battery-electric cars. However, a closer look shows renewed interest in hydrogen fuel cells, especially for long-range driving with fast refuelling. Toyota, BMW and Volkswagen are among those looking seriously at this option.
So, what if hydrogen vehicles become more predominant, as raw material supply issues become more concerning? Of course, there would then be a complete change in the polymer materials which predominate. Hydrogen transport pipelines in the supply infrastructure also provide
The polymer liner materials have typically been high-density polyethylene (HDPE); this material is chosen for its excellent combination of low hydrogen permeability and low cost. Other polymer systems are also being considered, such as nylons, which display lower hydrogen permeability.
In the hydrogen fuel cell itself, several components can be made from polymers, including the electrolyte membrane and the membrane electrode assembly, the bipolar plates (electrode plates) and peripheral parts such as gaskets and air ducts.
The electrolyte membrane serves as a gas barrier between fuel (hydrogen) at the anode and air at the cathode of the cell, as well as an electrical insulator between the electrodes. At the same time, it must transport protons from the anode compartment of the cell to the cathode compartment to complete the controlled oxidation of the fuel by air to form water (the only product of the reaction). The operating temperature is below the boiling point of water.
There are two major types of polymers used for these membranes: perfluorinated polymers with sulfonic acid groups, the most commonly known of which is Nafion, and hydrocarbon polymers with sulfonic acid groups, mostly based on polyetherketones and polyethersulfones.
References
- Demand for critical raw materials in electric vehicles
- Electric cars need far fewer raw materials
- Electric vehicle car polymers market
- Roadmap for future mobility
- Polymers for Hydrogen Infrastructure and Vehicle Fuel Systems
The views, opinions and technical analyses presented here are those of the author or advertiser, and are not necessarily those of ULProspector.com or UL. The appearance of this content in the UL Prospector Knowledge Center does not constitute an endorsement by UL or its affiliates.
All content is subject to copyright and may not be reproduced without prior authorization from UL or the content author.
The content has been made available for informational and educational purposes only. While the editors of this site may verify the accuracy of its content from time to time, we assume no responsibility for errors made by the author, editorial staff or any other contributor.
UL does not make any representations or warranties with respect to the accuracy, applicability, fitness or completeness of the content. UL does not warrant the performance, effectiveness or applicability of sites listed or linked to in any content.
