Research on the optimization of microstructure and enhancement of properties in ultra-thin electrolytic copper foil by rare-earth ions Ce3+ and La3+ additions

This study systematically investigates the synergistic optimization mechanisms of rare-earth ions Ce 3+ and La 3+ on the microstructure and mechanical properties of 4.5 μm ultra-thin electrolytic copper foils through a combination of experimental and theoretical calculations. The results demonstrate that at an optimal Ce 3+ /La 3+ concentration of 0.8 g/L, the copper foil achieves exceptional comprehensive performance: tensile strength of 591 MPa, elongation of 4.8 %, and reduced surface roughness (Ra = 24.4 nm). Electrochemical analysis reveals that rare-earth ions enhance cathodic polarization and nucleation density (6.57 × 10 4 /cm 2 ), and significantly optimize the electrodeposition process. Microstructural characterization shows that rare-earth ions promote grain refinement (average grain size 0.521 μm), increase twin density, and ensure uniform distribution of Cu x (La,Ce) 1-x precipitates. First-principles calculations confirm that the (220) crystal plane exhibits preferential orientation due to its lowest surface energy (1.285 J/m 2 ), consistent with experimental observations of texture evolution. The study reveals that rare-earth ions overcome the strength-ductility trade-off in traditional copper foils through a multi-scale synergistic mechanism involving “grain boundary-precipitate-twin-lattice” interactions, including Hall-Petch strengthening, solid solution distortion, precipitation pinning, and twin boundary obstruction. This work provides theoretical support and technical guidance for the defect-regulated design and industrial production of high-performance ultra-thin electrolytic copper foils.