Superior electrical conductivity-strength combination of an in-situ fabricated La2O3-doped copper/graphene composite conductor

In the past decade, Cu/graphene composite shows great potential in energy and electric power fields. Unfortunately, the uneven dispersion of graphene and the poor interfacial bonding between the copper and graphene have always been the bottlenecks hindering its development. Furthermore, it is almost impossible to obtain facile and scalable Cu/graphene materials with the combined high electrical conductivity and great strength through traditional ways. Here, we innovatively introduce lanthanum acetate as the carbon source to in-situ grow high-quality graphene and nano-sized La2O3 particles in copper through vacuum hot-press sintering to solve the above problems. The uniformly-distributed three-dimensional (3D) graphene network acts as an electron-transport channel, and the in-situ generated nano-sized La2O3 particles pin the Cu/graphene interface. Both the graphene and the nano-sized particles strengthen the matrix and hinder the matrix to soften at high temperatures. By further optimizing the sintering parameters, the doping content, the cold-drawing process, the La2O3-doped Cu/graphene composite wire with the high electrical conductivity of 95.5% IACS (International Annealed Copper Standard), great tensile strength of 539 MPa, and high softening temperature about 500 °C are obtained. The present work provides a new design idea for interface-strengthening Cu/graphene composites and establishes a suitable method for the large-scale production of high-performance Cu/graphene composites, which can be used at higher temperatures, such as the integrated circuit lead frame and the railway contact line.