Modular assembly of graphene-skinned Cu(111) foils into large-scale laminates with tailored interfaces and enhanced conductivity

Graphene-copper composites hold great promise for thermal and electrical management, yet their deployment is hindered by high grain boundary density, weak interfacial coupling, and limited scalability. Here we report a modular assembly strategy that transforms A3-sized single-crystalline graphene-skinned Cu(111) foils into bulk laminates with tailored interfaces and enhanced transport properties. The building blocks are synthesized via industrial-scale CVD system, combining temperature-gradient annealing with graphene epitaxial growth. Orientation-controlled stacking followed by spark plasma sintering yields dense laminates featuring only low-angle grain boundaries (<2°), preserved coherent Gr(0001)/Cu(111) interfaces, and a continuous graphene channel. The laminates achieve electrical conductivity up to 103.7% IACS and thermal conductivity exceeding 422.3 W·m^-1·K^-1, representing improvements of 5.5% and 8.2% respectively compared to commercial copper. Integrated heat spreaders exhibit substantially reduced thermal resistance (0.88 °C/W) with excellent stability. Extending this strategy to Gr/Ni(111) enables Cu-Gr-Ni heterostructures where graphene prevents intermetallic alloying. This work establishes a scalable paradigm for assembling macroscopic architectures from single-crystal, graphene-skinned building blocks for high-performance electronic packaging and multifunctional composites.