Graphene enhanced copper offers EV edge
GM funded research results in improved copper wire, process Metal Tech News – October 28, 2020
Last updated 10/27/2020 at 5:21pm
Working with General Motors, researchers at the Pacific Northwest National Laboratory have discovered that a tiny bit of graphene can increase the conductivity of copper wire by 5%.
"That may seem like a small amount, but it can make a big difference in motor efficiency," the Washington state lab penned in an article on the findings. "Higher conductivity also means that less copper is needed for the same efficiency, which can reduce the weight and volume of various components that are expected to power our future electric vehicles."
Graphene, which is made up of a single layer of carbon atoms organized in a hexagonal lattice, is by far the most highly conductive material known.
In addition to the more efficient flow of electrons, the research partially funded by GM found that the graphene enhanced wire is more ductile, which means it can be bent and stretched more than pure copper wire without breaking.
GM research and development engineers verified the higher conductivity copper wire can be welded, brazed, and formed in exactly the same way as conventional copper wire. This indicates seamless integration with existing motor manufacturing processes.
"To further lightweight motors, advances in materials is the new paradigm," said Darrell Herling, who works in Pacific Northwest National Laboratory's energy processes and materials division. "Higher conductivity copper could be a disruptive approach to lightweighting and/or increasing efficiency for any electric motor or wireless vehicle charging system."
A patented and patent pending process developed by the Pacific Northwest lab known as ShAPE, for shear assisted processing and extrusion, only needs about six pounds of graphene to make one million lb of this high efficiency copper.
"ShAPE's uniform dispersion of the graphene is the reason only really tiny amounts of additive are needed-about 6 parts per million of graphene flakes-to get a substantial improvement of 5% in conductivity," said Keerti Kappagantula, a material scientist at Pacific Northwest National Laboratory. "Other methods require large quantities of graphene, which is very expensive to make, and still have not approached the high conductivity we've demonstrated at a bulk scale."
A ShAPE machine developed by the lab combines metals and composite materials, and applies shear force to push the metals through dies. The pressure creates internal heat within the metal, which is an energy efficient way of softening the material so that it can be shaped into the products needed by the automotive and other sectors.
"ShAPE is the first process that has achieved improved conductivity in copper at the bulk scale, meaning it can produce materials in a size and format that industry currently uses, like wires and bars," said Glenn Grant, the lead researcher for the ShAPE project.
The Pacific Northwest National Laboratory team says the ShAPE process has overcome hurdles of clumping and pore spaces in structures encountered by previous research into mixing graphene with copper.
"The benefit of adding graphene to copper has been investigated before, but these efforts have primarily focused on thin films or layered structures that are extremely costly and time consuming to make," said Grant. "The ShAPE process is the first demonstration of considerable conductivity improvement in a copper-Graphene Composites made by a truly scalable process."
While ShAPE was developed as a way to make EVs more efficient, the advantages of this technology can apply to any industry that uses copper to transport electricity. Smartphones, wearable electronics, wind turbines and other generators, wireless chargers, and under-sea cables are among the applications that might benefit from the more efficient transport of electrons offered by graphene-doped copper.