Facile preparation and excellent properties of large-size ultrathin electrolytic copper foils with minor CNTs

Abstract

Carbon nanotubes (CNTs) have shown great potential in enhancing the performance of copper foils, however, the optimal CNTs concentration, strategies to suppress CNTs agglomeration, and the underlying strengthening mechanisms in Cu-CNTs composite foils (CCFs) remain to be fully elucidated. In this study, large-size ultrathin CCFs with low CNTs content were successfully fabricated via electrodeposition. The effects of CNTs content and agglomeration on the surface morphology, microstructure, mechanical properties, and electrical conductivity of CCFs were systematically investigated. The results revealed that CCFs with 40 mg/L CNTs exhibited an optimal balance between strength and ductility, achieving a tensile strength of 568.4 MPa and an elongation of 5.3 %, which represent 72.2 % and 104 % improvements over pure copper foil, respectively. The strengthening mechanisms were attributed to a synergistic effect of load transfer strengthening, dislocation strengthening, and fine grain strengthening, contributing approximately 35.8 %, 33.3 %, and 23.5 % to the overall strength, respectively. Additionally, tensile cracks were found to initiate preferentially at grain boundaries, while CNTs effectively inhibited crack propagation and delayed damage development. This study suggests that further optimization of the preparation process could enhance the performance of CCFs with low CNT content, providing valuable insights for the development of high-performance composite materials.