Researchers at the Pacific Northwest National Laboratory (PNNL) in the United States succeeded in increasing the conductivity of copper wires by about 5%. Although the amount of improvement is not large, it can have a great impact on the efficiency of the motor, because higher conductivity means that if the same efficiency is to be achieved, the amount of copper required will be less, which can be reduced The weight and volume of the various components that drive future electric vehicles.
The laboratory collaborated with General Motors to test reinforced copper wires on automotive electrical components. As a cost-sharing research project, the team is responsible for verifying that the conductivity of the copper wire has been improved, and also found that it has higher toughness, that is, it can be stretched longer before breaking. In terms of other physical properties, the copper wire behaves like ordinary copper wire, so it can also be used for welding, and it can withstand other mechanical stresses, and its performance will not be reduced. This means that assembling the motor will no longer require a special manufacturing method, just use the new copper composite material developed by PNNL.
This technology can be applied to any industry that uses copper to transmit electrical energy, including power transmission, electronic equipment, wireless chargers, motors, generators, submarine cables and batteries.
PNNL researchers use a brand-new, patent-pending manufacturing platform to add graphene, a highly conductive nano-scale carbon atom flake, to copper and produced copper wires. Compared with pure copper, the use of this new machine to mix and extrude metal and copper-containing composite materials has successfully improved the conductivity.
PNNL's ShAPE process (Shear Assisted Processing and Extrusion) can improve the performance of materials after extrusion. When a metal or composite material is pushed into a mold to create a new shape, rotating the metal or composite material applies a shearing force or reaction force to it. This innovative energy-saving method can create heat inside the metal by deforming it, and then soften it and turn it into wires, tubes and rods.
According to an electric vehicle report released by the U.S. Department of Energy in 2018, it is necessary to improve the efficiency of the motor to increase the power density of electric vehicles. In addition, components need to be built to accommodate vehicles with increasingly smaller available space. However, the current conductivity of materials and copper windings used in electric vehicles is limited, which also limits the size of the motor to be reduced.
It has been proven that it is very difficult to add graphene to copper because the additives cannot be uniformly mixed together and will form clumps and pore spaces inside the structure. However, the ShAPE process can eliminate the void space and at the same time evenly distribute the additives into the metal, which may be the reason for the improved conductivity.
General Motors` R&D engineers confirmed that this high-conductivity copper wire can be welded, brazed and formed in exactly the same way as traditional copper wires, which also means that it can be seamlessly integrated with existing motor manufacturing processes.