Comment China tightening its stranglehold on rare earth elements (REEs) makes now the perfect time for the automotive industry to start thinking about alternatives for EV motors, but not a single proposed solution appears ready for reality.
A trio at Oak Ridge National Laboratory in the US – who’ve been working on EV blueprints that don’t require rare earth magnets, and hence are less reliant on China – said this week there have been lots of promising developments in terms of removing REEs from electric car designs, but every single approach appears to have the same basic drawback.
“The bottom line is that replacing rare earth–based magnets with non–rare earth ones comes at a cost: Degraded motor performance,” the trio wrote for IEEE Spectrum. “We’re not there yet.”
Rare earth superiority
The 17 minerals considered REEs can be found in all sorts of modern technology, and in EVs they tend to be concentrated in the motors. When mixed with typical ferromagnetic elements such as iron or cobalt, REEs produce crystals that are both highly magnetic and very resistant to demagnetization, making them ideal for automotive use.
In EVs, rare earth magnets tend to take the form of neodymium iron boron (NdFeB), which has allowed motors to remain relatively light. Eliminating those REE magnets means going one of two routes: Either finding a REE-free permanent magnet with enough power, or swapping out all the permanent magnets in an EV motor for electromagnets.
Any potential solution would have to do three things that REE magnets do incredibly well, the trio said. They have a high maximum energy product, but also have high remanence (a measure of magnetic intensity left over when the magnetizing field is removed), and high coercivity (a measure of how difficult it is to demagnetize a magnet).
“No REE-free permanent magnet has all of these characteristics,” the Oak Ridge boffins said.
Even when a non-REE motor design can match the output of a REE one, it ends up being far too heavy. One such design, a spoke-ferrite magnet motor, ends up about 30 percent heavier than comparable REE motors.
“And there’s more bad news: Spoke-type motors can be complex to manufacture and pose mechanical challenges,” the team noted.
Another promising technology, magnets made from manganese bismuth, can actually produce the same amount of torque as an EV motor made with NdFeB magnets, according to the national lab team, and could cost up to 32 percent less. Unfortunately, getting to equal levels of torque means having around 60 percent more volume and 65 percent more mass than a typical EV motor.
In short, no one’s found a suitable replacement for rare earth magnets in EV motors yet, and time’s ticking.
The China problem
China, which is aggressively investing in and has high hopes for its own EV industry, announced this week it was going to start treating all rare earth elements in the country as belonging to the state.
As the largest source in the world of rare earth elements, the Middle Kingdom produces around 60 percent of the materials globally, and also processes nearly 90 percent, giving it a stranglehold on minerals critical for today’s electric vehicles as well as other technologies, emerging or otherwise.
By declaring all REEs property of Beijing, China could choose to cut off exports, just like it did last year when the country banned exporting rare earth extraction and processing technologies.
Turnabout, as they say, is fair play. China wants to corner the global EV market with its own offerings, America hits imports of Chinese electric vehicles with eye-watering tariffs, and now this.
Getting around China’s grip on REEs means leaning into some of the more promising EV motor concepts the ORNL team said are in development around the US – such as aluminum-nickel-cobalt alloy metals, rotary transformers, and new materials including high-conductivity copper and high-silicon steel.
Relying on those technologies isn’t exactly a good bet though. The researchers didn’t give a timeline on commercialization of any non-REE EV motor technology, and didn’t respond to questions.
Their briefing still retains a bit of optimism, with the trio noting “research is beginning to yield intriguing and encouraging results,” and that “it’s perfectly feasible that REE-free motors will one day become mainstream.”
Whether any new forms of EV motors will emerge before China decides to lock down its rare earth elements is unknown, and just another source of worry as US-China relations get rockier. ®
