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Rare Earth Alternatives for Electric Vehicle Magnets
Date:2023-06-30
Electrified vehicles produce torque when the motors in their rotors try to align with magnetic fields created in stator windings by traction inverters. That’s how they get you from point A to point B. But these powerful rotors require rare-earth magnets that are expensive and difficult to obtain — and the supply chain is fraught.
The most commonly used rare earth magnets are neodymium-iron-boron (NdFeB), which offer the highest magnetic field per volume, enabling light and compact product designs. However, China controls 90% of the world’s supply of rare earth elements, a situation that has raised concerns over national security and the environment.
While the price of NdFeB magnets has recovered closer to historical levels, the scarcity of the raw materials is still a concern for some governments and manufacturers. GM, for example, has formed strategic partnerships with MP Materials of Las Vegas and Vacuumschmelze of Frankfurt to help it domestically source key materials for its electric vehicles. But for some, that may not be enough.
The rotors of most electric car engines use rare earth magnets, but the industry has been trying to find alternatives to cut costs and improve performance. One of the most promising is ferrite, which has good magnetic properties and can be made more cheaply than NdFeB magnets. But experts who spoke to IEEE Spectrum were unanimous in saying that ferrite magnets won’t be suitable for most electric vehicle motors because they are weak and would need a large amount of cobalt, a metal that is in short supply.
Another potential substitute for NdFeB is a new magnet from Niron Technologies, which Blackburn says can be made with 20%-50% less neodymium. The company also aims to develop magnets with higher flux and coercivity, and better temperature coefficients, than NdFeB.
TDK has been working to minimize the requirement for heavy rare-earth elements such as dysprosium and terbium, which are used in neodymium magnets to make them more heat resistant. In 2012, it introduced the industry’s first neodymium magnet that contains no Dy or Tb.
The firm is also working to increase the production capacity of neodymium-iron-boron magnets, and is using a process called super-hot melt casting. This allows the production of smaller, more dense magnets and reduces energy losses. Unlike sintering, which involves heating and cooling the magents, super-hot melt casting does not degrade the material and can be used multiple times. TDK expects to introduce the technology to mass production next year. This will help it meet future demand while minimizing the amount of raw material required. It is also possible to manufacture larger-volume magnets by using this method. These could be suitable for larger electric vehicles like trucks and buses. In fact, TDK already supplies such magnets to BMW.
The most commonly used rare earth magnets are neodymium-iron-boron (NdFeB), which offer the highest magnetic field per volume, enabling light and compact product designs. However, China controls 90% of the world’s supply of rare earth elements, a situation that has raised concerns over national security and the environment.
While the price of NdFeB magnets has recovered closer to historical levels, the scarcity of the raw materials is still a concern for some governments and manufacturers. GM, for example, has formed strategic partnerships with MP Materials of Las Vegas and Vacuumschmelze of Frankfurt to help it domestically source key materials for its electric vehicles. But for some, that may not be enough.
The rotors of most electric car engines use rare earth magnets, but the industry has been trying to find alternatives to cut costs and improve performance. One of the most promising is ferrite, which has good magnetic properties and can be made more cheaply than NdFeB magnets. But experts who spoke to IEEE Spectrum were unanimous in saying that ferrite magnets won’t be suitable for most electric vehicle motors because they are weak and would need a large amount of cobalt, a metal that is in short supply.
Another potential substitute for NdFeB is a new magnet from Niron Technologies, which Blackburn says can be made with 20%-50% less neodymium. The company also aims to develop magnets with higher flux and coercivity, and better temperature coefficients, than NdFeB.
TDK has been working to minimize the requirement for heavy rare-earth elements such as dysprosium and terbium, which are used in neodymium magnets to make them more heat resistant. In 2012, it introduced the industry’s first neodymium magnet that contains no Dy or Tb.
The firm is also working to increase the production capacity of neodymium-iron-boron magnets, and is using a process called super-hot melt casting. This allows the production of smaller, more dense magnets and reduces energy losses. Unlike sintering, which involves heating and cooling the magents, super-hot melt casting does not degrade the material and can be used multiple times. TDK expects to introduce the technology to mass production next year. This will help it meet future demand while minimizing the amount of raw material required. It is also possible to manufacture larger-volume magnets by using this method. These could be suitable for larger electric vehicles like trucks and buses. In fact, TDK already supplies such magnets to BMW.
