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Heat accumulation has emerged as a critical issue that affects the performance and reliability of modern electronic devices in their evolving toward miniaturization, high power density and high integration. The application of thermal interface materials (TIMs) as a thermal management strategy is commonly employed to tackle this problem. Herein, we report the development and characterization of highly thermally conductive but electrically insulating Cu@Al 2 O 3 /epoxy composites. Stemming from the excellent thermal conductivity of Cu, the Cu@Al 2 O 3 /epoxy composites exhibit thermal conductivity of 1.32 W/m·K at 10 vol% filler content, which is nearly 7 times higher than that of the epoxy resin. Simultaneously, the Cu@Al 2 O 3 /epoxy composites still retain a high electrical resistivity of 2.3 × 1013 Ω·cm, which is 6 orders of magnitude greater than that of Cu/epoxy composites without Al 2 O 3 barrier layers, because the dense nanoscale insulating Al 2 O 3 shell effectively inhibits the electron transfer. In addition, the Cu@Al 2 O 3 /epoxy composites possess lower dielectric constant and dielectric loss, and better mechanical properties than those of Cu/epoxy composites. [Display omitted] • Core-shell Cu@Al 2 O 3 particles were rationally designed and prepared by a simple and scalable solution-based process. • Cu@Al 2 O 3 /epoxy composites were fabricated as thermal interface materials for thermal management application. • Enhanced thermal conductivity and high electrical insulation was achieved by Cu@Al 2 O 3 /epoxy at a low filler content. • Cu@Al 2 O 3 /epoxy composites possess better dielectric and mechanical performances than those of Cu/epoxy composites. [ABSTRACT FROM AUTHOR]

Regulating the composition and microstructure of nanomaterials is a major challenge in the development of high-performance materials for electromagnetic wave (EMW) absorption. This paper introduces a new lightweight EMW-absorbing material Co@N/C with a yolk–shell structure and compositions of ferromagnetic metal and carbon materials. The minimum reflection loss (RL min) of the as-designed Co@N/C nanospheres with a filler loading of 25 wt% reaches −67.68 dB and the effective absorption bandwidth of a 1.9 mm thickness is 5.3 GHz. The exceptional absorption performance of the EMW absorption is primarily achieved through the synergistic effect between the Co–carbonaceous material and the yolk–shell structure, which optimizes the impedance matching. The polarization loss, conductivity loss, magnetic loss, and multiple scattering mainly contribute to the excellent EMW-absorption ability of the materials. The proposed method for regulating the structure and morphology of Co@N/C can efficiently construct high-performance EMW absorbers. [Display omitted] • Yolk-Shell structure nanocomposite with excellent electromagnetic wave absorption properties was synthesized. • An excellent reflection loss (RL) of −67.68 dB at 15.88 GHz with an ultra-thin thickness (1.7 mm). • Effective absorption bandwidth (<−10 dB) up to 5.3 GHz under a single thickness (1.9 mm). [ABSTRACT FROM AUTHOR]