Transformative Breakthrough in Strength-Conductivity-Thermal Stability of Copper Foils Enabled by Gradient Super-Nano Domains
Copper-based conductor materials, particularly copper foils, are indispensable for integrated circuit substrates and lithium battery current collectors. The progressive miniaturization of electronic devices demands foils thinner than 10 μm, yet achieving simultaneous ultra-high strength, high ductility, high electrical conductivity, and thermal stability remains a principal bottleneck. Rolled copper foils offer strengths of 200–500 MPa and conductivities of 97–100% IACS, but face production stability limits at reduced thicknesses. Electrolytic copper foils achieve strengths of 600–700 MPa via nanocrystalline refinement but suffer from poor thermal stability and room-temperature self-annealing. Only specialized alloys like Cu-Cr-Zr and Cu-Ag reach the 'double-70' benchmark (strength >700 MPa, conductivity >70% IACS). This highlight reports a transformative advance by Lu's research group, achieving 'double-90' properties (tensile strength >900 MPa, electrical conductivity >90% IACS) in pure copper foils through a gradient super-nano domain (GSD) structure. The GSD architecture, fabricated via electrodeposition under industrial conditions, comprises periodically distributed domains with semi-coherent interfaces and solute atoms (C, O, Cl) that minimize electron scattering. This innovation overcomes the traditional strength-conductivity trade-off, offering a scalable route to high-performance copper foils for advanced chip interconnects, flexible electronics, and ultrathin battery current collectors.