Scientists at the Oak Ridge National Laboratory in the United States have used new technology to create a composite material that can increase the current capacity of copper wires, thereby providing a traction motor that can be scaled for ultra-efficient, high-power density electric vehicles New materials.
This research aims to reduce the barriers that hinder the widespread use of electric vehicles, including reducing the cost of ownership and improving the performance and life of components such as motors and power electronics. The material can be deployed in any component that uses copper, including more efficient bus bars and smaller connectors for electric vehicle traction inverters and for applications such as wireless and wired charging systems.
In order to produce conductive materials with lighter weight and better performance, researchers deposited carbon nanotubes on a flat copper substrate to form a metal matrix composite material whose current handling capacity and mechanical properties are better than using copper alone.
Adding carbon nanotubes to the copper matrix to improve electrical conductivity and mechanical properties is not a new idea.
Carbon nanotubes are an excellent choice due to their light weight, high strength and electrical conductivity. But other researchers' past attempts on composite materials have resulted in very short material lengths of only micrometers or millimeters, coupled with limited flexibility, or long materials have poor performance.
The team decided to try to deposit single-walled carbon nanotubes using electrospinning, which is a commercially viable method that creates fibers when a liquid is sprayed through an electric field. Researchers from the Department of Chemical Sciences explained that the technology can control the structure and orientation of deposited materials. In this case, the process allows scientists to successfully orient the carbon nanotubes in a general direction to facilitate the flow of electric current.
Then, the team used magnetron sputtering (a vacuum coating technique) to add a thin layer of copper film on the carbon nanotube-coated copper strip. The coated sample is then annealed in a vacuum furnace to form a dense and uniform copper layer, thereby creating a highly conductive copper-carbon nanotube network and allowing copper to diffuse into the carbon nanotube matrix.
Using this method, scientists have created a copper-carbon nanotube composite material with a length of 10 cm and a width of 4 cm, which has excellent properties. The microstructure characteristics of the material are analyzed by the instrument of the Nanomaterials Science Center of the US Department of Energy's Science User Facilities.
The researchers found that compared with pure copper, the current capacity of the composite material increased by 14%, and the mechanical properties increased by 20%.
The chief researcher of the project said: "By embedding all the outstanding properties of carbon nanotubes into the copper matrix, our goal is to increase mechanical strength, reduce weight and increase current capacity. Then you will get better conductors and power Lower power consumption improves the efficiency and performance of the equipment. For example, improved performance means that we can reduce the size and increase the power density of advanced motor systems."
This work is based on a long history of superconductivity research, which has produced excellent materials with low resistance and conductivity. The laboratory’s superconducting wire technology has been licensed to several industrial suppliers to achieve high-capacity power transmission while minimizing power loss.
Researchers say that although breakthroughs in new composite materials have a direct impact on motors, they can also improve electrification in applications where efficiency, quality, and size are key indicators. He said that the improved performance characteristics achieved through commercially viable technologies mean new possibilities for designing advanced conductors for various electrical systems and industrial applications.
The team is also investigating the use of double-walled carbon nanotubes and other deposition techniques (such as ultrasonic coating combined with a roll-to-roll system) to produce samples about 1 meter in length.
The person in charge pointed out: "The motor is basically a combination of metal-steel sheet and copper winding. In order to achieve the 2025 electric vehicle goal of the U.S. Department of Energy's Automotive Technology Office, we need to increase the power density of the electric drive and reduce the size of the electric motor. 8 times, which means improving material properties."