Preparation of ultra-thin sandwich Cu-Cu/CNTs-Cu composite foil with high tensile strength by electrodeposition

In this experiment, CNTs were co-deposited with Cu2+ in the acid electrolyte by acidizing sulfuric and nitric acid and protonating cationic surfactant poly diallyldimethylammonium chloride (PDDA). Subsequently, Cu-Cu/CNTs-Cu composite copper foil (1) with a sandwich thickness of 8 μm was prepared by combining additives of 3-mercapto-1-propanesulfonate (MPS) and Cl−. The results show that the resistivity of the composite foil is 1.89 × 10−8 Ω·m, which increased only 2%. The tensile strength σ is 582 MPa, the elongation ε is 3.27%, and the elastic modulus and hardness of the nano-indentation test are 97.5 GPa and 2.38 GPa respectively. These are due to the uniform distribution of CNTs as enhanced phases in the crystal, and importantly, nano twins appear in size smaller than 10 nm, thereby constructing a micro-nano organizational structure and greatly improving the mechanical properties of the composite foil. In addition, the main peak of XRD is shifted from (1 1 1) to (2 2 0) crystal plane, which shows reduced stress in grains, effectively inhibits the phenomenon of self-annealing, and ensures long-term stability of copper foil microstructure.