Conductive metals like copper and aluminum are crucial for several industry sectors, such as electronics, transportation, wire and cable, and power transmission. Increasing the conductivity of these metals can lead to major improvements in efficiency. For example, a 10 percent increase in copper conductivity could improve overall motor efficiency for electric vehicles by >2 percent, while a similar increase in the conductivity of aluminum could lead to >15 percent lighter conductor cables, making power lines cheaper, safer, and longer-lasting.

Improving the conductivity of these metals, however, is no small feat. Conventional physics had suggested that peak conductivity of a metal is achieved in its purest form, and that additives decrease conductivity. For decades, researchers have, through trial and error, sought to produce metal-carbon composites with increased conductivity, called “ultra-conductors.” However, successes have been limited and not at industry-relevant scales.

Researchers at Pacific Northwest National Laboratory (PNNL) have changed that status quo, producing both aluminum-graphene and copper-graphene composites that demonstrate significantly improved conductivity.

The aluminum-graphene composite, demonstrated as a wire at 1-meter scale, is 7 percent more conductive than aluminum. This is an unprecedented feat, unrivaled even at micron or nanometer scale, let alone the practical, meters-long wire scale achieved by PNNL.

Meanwhile, the copper-graphene composite, demonstrated as a wire at 1-meter scale, is 5 percent more conductive than copper. This level of improvement in conductivity, again, had never been demonstrated in a functional wire form. Further, the temperature coefficient of resistance of ultra-conductors is lower than comparable commercial alloys—meaning that the conductivity improvements are realized (or more) at the elevated temperatures where these conductors typically operate.

These revolutionary materials were developed using first-of-their-kind physics models created at PNNL that illuminated the role of carbon additives in conductivity. With that fundamental knowledge in hand, PNNL scientists used Shear Assisted Processing and Extrusion (ShAPE™)—a novel, patented extrusion technique developed at PNNL—to physically produce the modeled alloys at an industry-relevant scale. ShAPE’s unique advantages enabled the use of low-cost graphene in the production of the aluminum-graphene composite.