Highly conductive and cycling stable Ag nanoparticles and aligned single-walled carbon nanotubes composite films prepared by direct ink writing

High conductivity and reliability under cyclic loading are crucial for designing high-performance conformal printed circuits. In this study, shear stress induced in the direct ink writing (DIW) nozzle was utilized to align Single-Walled Carbon Nanotubes (SWCNTs) along the printing direction within Ag-SWCNT composite films. The results indicate that at an optimal SWCNT content of 0.25 wt%, the aligned SWCNTs bridged high-resistivity grain boundaries and spanned the voids formed by Ostwald ripening, resulting in a reduction of the resistivity of the Ag-SWCNT composite film by 36.2% compared to the Ag film. The aligned SWCNTs suppressed crack propagation through fiber pull-out and bridging effects, enhancing the mechanical stability of the Ag-SWCNT composite film. After 100,000 cycles at a strain of 0.5%, the relative resistivity (R/R0) of the Ag-SWCNT composite film remains at 1.68, which is in contrast to the fracture failure of the Ag film after 1000 cycles. This study presents a novel approach for high-performance conformal circuit printing and offers practical guidance for the reliable application of composite films in critical service environments.