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ELECTRICAL CAPACITY Copper wire electrical capacity boosted by new material

| Author / Editor: Luke James / Johanna Erbacher

Scientists at Oak Ridge National Laboratory have utilized new techniques to create a composite material that they say increases the electrical current capacity of copper wires. This, they claim, provides a new material that could be used in next generation electric vehicles.

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Scientists at ORNL have used a new technique to create a composite material that makes copper extra conductive.
Scientists at ORNL have used a new technique to create a composite material that makes copper extra conductive.
(Source: Andy Sproles/ORNL.)

In research published in the journal Applied Nano Materials earlier this year, research scientists at Oak Ridge National Laboratory (ORNL) presented a new technique which they used to create a new composite that increases the electrical current capacity of copper wires.

The scientists claim that this technique provides a new material that’s viable for use at scale in ultra-efficient, power-dense electric vehicle applications such as traction motors.

Creating the lightweight conductive material

To produce their lightweight conductive material with enhanced performance metrics, the ORNL research team used carbon nanotubes (CNTs). They aligned CNTs on flat copper substrates to create a metal-matrix composite material with better current handling capacity and mechanical properties than standalone copper.

This isn’t exactly a novel idea, though. Incorporating CNTs into a copper matrix to boost conductivity and mechanical performance is something that has been explored before. However, previous attempts at creating composites have resulted in short material lengths, some only micrometers long, with limited scalability.

In this study, the researchers overcame this problem by experimenting with a new technique. They deposited single-wall CNTs using an electrospinning method which creates fibers using a jet of liquid that speeds through an electric field. This technique provided the researchers with full control over the structure and orientation of deposited materials. And in this case, the process allowed the research team to orient the CNTs in one general direction to improve the flow of electricity.

The researchers then used a vacuum coating technique to add thin layers of copper film on top of the CNT-coated copper substrates. The coated samples were then annealed in a vacuum furnace to produce a highly conductive Cu-CNT network consisting of a dense, uniform copper layer which allows diffusion of copper into the CNT matrix.

Breaking down the barriers to widespread electric vehicle adoption

The result was a Cu-CNT composite material 10 cm in length and 4 cm in width with dramatically enhanced properties. Upon analysis of the material’s properties, the researchers found that the composite achieved 14% greater current capacity with up to 20% improved mechanical properties when compared with pure copper.

By embedding the properties of CNTs into a copper matrix, the research team achieved what they set out to do—create a material with “better mechanical strength, lighter weight and higher current capacity,” according to Tolga Aytug, lead investigator for the research project.

The result, according to the study, is a better conductor with less power loss and increased efficiency and performance. This means, for example, applications such as advanced motor systems in electric vehicles could benefit from increased power density. Indeed, the research itself was aimed at reducing existing barriers to widespread adoption of electric vehicles, including improving their performance, extending the component lifecycle, and cutting down the cost of ownership.

The new composite could also improve electrification in applications where metrics like mass, size, and efficiency are important. “The improved performance characteristics, accomplished with commercially viable techniques, means new possibilities for designing advanced conductors for a broad range of electrical systems and industrial applications,” Aytug added.

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