Electromechanical Behavior of Axially Continuous Graphene-Copper Wires.

Graphene-copper (Gr-Cu) composite conductors have demonstrated Gr-enhanced electrical and thermal properties. However, the conductors' coupled mechanical and electrical responses remain unexplored despite the importance of their mechanical flexibility and robustness. Here, the electromechanical behavior of a recently developed microscale Gr-Cu composite, called axially continuous graphene-copper (ACGC) wire, has been investigated by developing and utilizing a customized tensile testing method. Experimental studies have shown that 80 μm-diameter ACGC (hereafter ACGC80) wires exhibit 3.681% and 3.173% higher compared to as-received and annealed Cu wires, respectively. More importantly, the Gr-enhanced electrical performance of the ACGC80 has been observed even after significant plastic deformation under uniaxial tension. To be specific, the conductivity of ACGC80 is 3.139%, 3.144%, and 3.088% higher than that of annealed copper wire at 3, 6, and 9% strain, respectively. Analysis indicates that ACGC80 deforms by forming highly localized plastic deformation zones along its length. This result suggests that graphene in ACGC80 serves as an effective electron pathway even after applying a large strain because the pronounced damage to graphene is limited to only a small fraction of ACGC80. The ACGC80 conductor has great potential to advance emerging applications in flexible interconnects, wearable electronics, and high-power transmission for microchips.