PNNL scientists have succeeded in increasing the conductivity of aluminum.

Scientists at PNNL (Pacific Northwest National Laboratory) are proposing how to increase the conductivity of aluminum, making it economically competitive with copper.

The first simulation of aluminum conductivity opens the door to experiments that, if fully realized, could lead to an ultraconductive aluminum alternative to copper that would be useful in markets beyond transmission lines, revolutionizing vehicles, electronics and the power grid, according to the authors.

"What if you could make aluminum more conductive, even 80% or 90% as conductive as copper? You could replace copper and that would make a big difference because more conductive aluminum is lighter, cheaper and more abundant," Keerti Kappagantula, a materials scientist at PNNL and co-author of the research, said in a statement. "That's the general problem we're trying to solve."

Demand for copper is rapidly outstripping its current availability, driving up its cost. Copper is an excellent electrical conductor, used in everything from portable electronic devices to undersea transmission cables that power the Internet, but there is no escaping the fact that copper is becoming less available and more expensive.

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These challenges are expected to worsen with the growing number of electric vehicles, which require twice as much copper as traditional vehicles. In addition, copper is heavy, which reduces the efficiency of electric vehicles.

Aluminum is only one-third the price and weight of copper, but has only 60% conductivity. Aluminum's relatively low conductivity can be a limitation in some real-world applications.

"Conductivity is key because lighter wire with equivalent conductivity can be used to design lighter motors and other electrical components, so your vehicle can travel longer distances," Kappagantula said.

"Everything from the electronics in an automobile to generating power and transmitting that power to your home through the grid to charge your car battery, anything that runs on electricity, everything can become more efficient."

Increase conductivity

Increasing the conductivity of aluminum would be a game changer. "For years, we thought that metals could not be made more conductive. But that's not the case," Kappagantula explained. "If you alter the structure of the metal and introduce the right additives, you can actually influence its properties."

To begin determining how much the conductivity of aluminum could be increased, Kappangantula and PNNL postdoctoral fellow Aditya Nittala partnered with Professor David Drabold and graduate student Kashi Subedi of Ohio University to identify the effects of temperature and structural defects on the conductivity of aluminum and develop an atom-by-atom recipe for increasing its conductivity.

This type of molecular simulation had never been done for metals before, so the researchers had to be creative. They looked to semiconductors for inspiration because previous research had successfully simulated conductivity in these materials based on silicon and some metal oxides.

The team adapted these concepts to work with aluminum and simulated what would happen to the metal's conductivity if individual atoms were removed or rearranged from its structure. These small changes added up to big gains in overall conductivity.

Search for it in other metals

The model's ability to simulate real-world conditions surprised even the team. "We didn't think these results would be so close to reality," Kappagantula said. 

"This model simulation that is based on the atomic structure and its different states is so accurate that I said, 'Wow, that's right on target.' It's very exciting."

 With a theoretical recipe for altering the metal's conductivity now clear, the researchers plan to see how much they can increase the conductivity of aluminum in the laboratory to match the theory with experimental results. They are also exploring the possibility of increasing the conductivity of other metals using the same simulations.

The research is published in Physical Review B, and the team expects that more conductive aluminum will have far-reaching implications: any application that uses electricity or copper could benefit from the development of ultraconductive, lightweight and affordable aluminum.