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.

Multilayer graphene films demonstrate superior electrical and thermal conductivity, mechanical properties, and barrier performance compared to monolayer, thereby exhibiting greater potential for industrial applications. However, the synthesis of multilayer graphene films continues to face critical challenges, primarily including uncontrollable layer numbers, incomplete understanding of growth mechanisms, and poor reproducibility and scalability in mass production. This study introduces the “fractional layer” concept and corresponding mathematical model to precisely quantify graphene layers for the first time. Using this metric, we systematically established growth principles and process windows for layer-controlled graphene synthesis on copper substrates and elucidated the multilayer growth mechanism governed by modulating the lateral growth and vertical growth kinetics. Based on this theoretical framework, the continuous preparation of 2.3-layer graphene films was achieved via industrial scale roll-to-roll chemical vapor deposition equipment, exhibiting exceptional macroscopic uniformity and demonstrating significant potential for applications in transparent, flexible electrothermal heaters. Our work will establish a solid material foundation for the industrial application of multilayer graphene films and offer novel insights into the layer-controlled synthesis of other two-dimensional materials.