Effective electrical conductivity of nanocarbon-metal composites made by the electrocharging assisted process*

Robust materials with high conductivity are essential to electronic devices and systems. Novel composites called “covetics” have the potential to improve upon the electrical conductivity of established metals and alloys, including Al and Cu, by incorporating carbon nanostructures known for their superior electrical properties. During fabrication, electric current applied to the melt containing a C precursor is believed to ionize carbon atoms and cause nanoscale graphitic ribbons and chains to form within the metal lattice. This work combines fundamental assumptions about the nature of covetics, specifically a tightly bound metal-carbon interface, with a simple effective-medium model to estimate the bulk conductivity of ideal Al and Cu covetics with randomly distributed graphene nanoribbons. Density-functional theory estimates of charge transfer at the graphene-metal interface, local electrical conductivity measurements, and transmission electron microscopy investigation of the interface region provide inputs to the model. We find potential for improvements on the order of 10% under ideal conditions, but substantial processing challenges remain before these gains may be realized on an industrial scale.