Researchers Develop a Copper-Based Composite Material to Increase Power Density in Vehicles

November 08, 2020 by Stephanie Leonida

Oak Ridge National Laboratory Researchers aim to promote electric vehicle market adoption through development of a high-performing conductive material for use in vehicle motor systems.

Scientists working at the Oak Ridge National Laboratory (ORNL) have generated a composite material that shows improved electrical and mechanical properties when compared with pure copper. 

The material was designed to help promote wider market adoption of electric vehicles (EVs). The technology is hoped to help reduce challenges surrounding this vision, including cutting the cost of ownership and improving the performance of certain EV components. Any component that uses copper could make use of the ORNL-developed composite material. This may include smaller connectors for electric vehicle traction inverters, more efficient bus bars, applications such as wireless and wired charging systems.


ORNL researchers develop a copper-carbon nanotubule composite material for EVs
ORNL researchers develop a copper-carbon nanotubule composite material for EVs. Image used courtesy of ORNL 


The Research Behind the Ultraconductive Composite 

The ORNL researchers used unique materials and tried experiments to create a highly conductive copper-carbon nanotubule composite. Carbon nanotubes (CNTs) were deposited and aligned on flat copper substrates. This resulted in the formation of the metal-matrix composite material. 

Although the use of CNTs along with a copper matrix is not a new idea within the realm of research, past experimentation could not achieve appropriate material lengths with good scalability or performance. The ORNL researchers decided to change tactics with regard to design and methodology. They deposited single-wall CNTs using electrospinning. This technique creates fibers as a stream of liquid rushes through an electric field. The technique provided the scientists with sufficient control so that they could successfully orient the CNTs in one general direction to enhance electricity flow. 

The research team then added thin layers of copper film onto the CNT-coated copper tapes. To do this, the team used a vacuum coating technique known as magnetron sputtering. The coated tapes were then annealed within a vacuum furnace to produce the end product. The copper-carbon nanotube composite was made. 

The material measured in at 10 centimeters long and 4 centimeters wide, was shown to reach 14% greater current capacity and exhibited improved mechanical properties (by 20%) when compared with pure copper.


ORNL senior researcher Tolga Aytug.
ORNL senior researcher Tolga Aytug. Image used courtesy of ORNL 


In a recent news release,  the lead investigator for the project provided his view on the research: “By embedding all the great properties of carbon nanotubes into a copper matrix, we are aiming for better mechanical strength, lighter weight and higher current capacity. Then you get a better conductor with less power loss, which in turn increases the efficiency and performance of the device. Improved performance, for instance, means we can reduce volume and increase the power density in advanced motor systems.”

In addition to motor systems, the ORNL researchers believe that the copper-carbon nanotubule composite could be used for other industrial applications including those that require improvements in efficiency, mass, and size.