Macro copper-graphene composites with enhanced electrical conductivity

•Copper electrical conductivity was enhanced by 2.7% in 3D macro-scale through graphene addition•Higher performance achieved via synergistic optimization of graphene defect density and content•Higher conductivity despite smaller copper grains suggest graphene engages in carrier transport Composites demonstrating enhanced electrical conductivity compared to copper have been highly sought after for their advantages in efficient energy transport behavior. While such conductors have been demonstrated in 1D (nanowires) and 2D (films) samples, achieving similar behavior in 3D has been challenging owing to the limitations of the synthesis techniques used. In this paper, novel macro-scale 3D copper conductors were demonstrated with increased electrical conductivity through the addition of graphene. Hot extrusion was used to manufacture 12 AWG copper-graphene composite wires with varying graphene content and defect density. Graphene defect density was measured using Raman spectroscopy. Results showed that the electrical conductivity of composites with low defect density graphene increased as a function of graphene content. Comparatively composites with high defect density graphene demonstrated lower electrical conductivity. This study provides first-of-its-kind evidence of 3D metal composites whose bulk electrical performance has been enhanced using graphene additive in minute quantities (15 ppm). Further developments in this area are essential to achieve high performance composite conductors that can improve energy transport efficiency and pave way for industrial adoption of such materials in the future.