This has been an avenue of research for some time: the 2015 Sustainable Materials and Technologies paper noted that finding a way to reliably reduce the grain size of components of rare earth magnets could increase the magnetic energy stored in a magnet. The automaker also reduced the grain size of the metals in the magnet. Instead, the company composed the magnet so that most of the lanthanum and cerium grains were internal to the magnet, and most of the neodymium grains were on the outside. The company says that simply replacing the neodymium in a magnet with lanthanum and cerium results in a sub-par magnet with reduced coercivity and reduced heat resistance, meaning motor performance will suffer. Toyota used a few tricks to reduce its neodymium use. Ideally, a cheaper magnet could result in cheaper hybrid and all-electric vehicles. But Reuters notes that while neodymium costs about $100 per kg and dysprosium costs about $400 per kg, lanthanum and cerium cost about $5 to $7 per kg. Certainly, this doesn't get rid of many of the issues with neodymium: lanthanum and cerium are still predominantly mined in China and, as with most rare earths, they can be environmentally destructive to produce. Instead of neodymium or dysprosium, the magnet uses less-expensive rare-earth metals lanthanum and cerium. The Chevy Bolt also uses a neodymium-based magnet, Roskill says. But the Model 3 reportedly does use a PM system, likely because magnets economize space and weight (which can affect battery range), and such motors tend to have better acceleration. Tesla famously eschewed magnets in its Model S and Model X vehicles, opting for a heavier copper induction system. ( Components-maker Bosch has also worked on building systems that use both induction motors and permanent magnet motors in the same product, for front and rear axles, for example.) Most hybrid vehicles (HEVs) use PM systems: with a hybrid system you need both a battery and an internal combustion engine, so reducing the size of the motor is paramount. Roskill notes PM-based systems tend to be lighter and smaller, since they can rely on the NdFeB magnet inside of them for a constant magnetic field. By contrast, induction motors (which are much more common) use no magnets and rely on current flowing through the stator windings to induce a magnetic field, which leads to the rotation of the rotor.Īs you might imagine, there are several trade-offs between PM motors and magnet-less induction motors.

In other designs, the magnets can be embedded in the stator, or the magnets can be arranged to work with a DC magnetic field. When wire windings in the stator are electrified, the magnetic attraction causes the rotor to rotate. In a Permanent Magnet (PM) AC car motor, NdFeB magnets are often embedded in the rotor. When paired with dysprosium, NdFeB magnets have high coercivity, that is, 'the ability to resist demagnetization once magnetized,' according to a 2015 paper from Sustainable Materials and Technologies. NdFeB magnets are able to produce a strong magnetic field in small volumes. (In fact, mining consultancy Roskill notes that few automakers use terbium in magnets anymore, though dysprosium is still commonly added to magnets with neodymium.) What do these magnets do? The new magnet Toyota developed also uses no terbium or dysprosium, which can be added to neodymium to improve its operability at high heat, above 100 degrees Celsius (212 degrees Fahrenheit). If China were to use rare-earth access as a geopolitical tool again, it could significantly impact companies like Toyota that depend on rare earths to build flagship products like the Prius. That country threatened to stop exporting neodymium and other rare earths in 2011, which sent prices for the metals soaring. Further Reading Toyota in “production engineering” for a solid state battery, WSJ saysRare-earth magnets are used in many hybrid vehicles, some all-electric vehicles, and in other applications like wind turbines and robotics.Īlthough 'rare' is a bit of a misnomer for a material like neodymium (high demand has led to relatively high production volumes), Toyota notes that 'there are concerns that shortages will develop as electrified vehicles, including hybrid and battery electric vehicles, become increasingly popular in the future.' That concern is compounded by the concentration of rare-earth mining: although attempts have been made to mine rare-earth metals in the US and other parts of the world, a preponderance of rare-earth mining occurs in China.

Neo magnet