▎ 摘　　要

Electromagnetic interference (EMI) shielding performance of composites are usually limited by their electrical conductivity and permeability, which largely depend on the conductive filler content, aspect ratio, magnetic permeability, etc. Higher filler content usually leads to high cost, poor dispersion and easy agglomeration, making the polymer composites mechanically brittle and difficult to process. Therefore, it is highly desirable to develop composite with low conductive filler content while maintaining its high EMI shielding performance. Here, in our work a high-performance EMI shielding was realized in nacre-mimetic graphene/polymer composites with extremely low graphene loading. A nacre-mimetic 3D conductive graphene network with biaxial aligned lamellar structure was prepared by a unique bidirectional freezing technique. With such a nacre-mimetic, highly aligned network, our graphene/polymer composites exhibit anisotropic conductivities, mechanical properties and therefore remarkable EMI shielding effectiveness at an extremely low graphene content. Specifically, the biomimetic composites with 0.42 wt% graphene content shows an enhanced EMI shielding effectiveness of similar to 65 dB after annealing the graphene aerogels at 2500 degrees C, which is comparable to the copper foil. More remarkably, as the composite is low in density, its specific shielding effectiveness is even higher than that of metal foils and solid materials with high conductive filler content. (C) 2019 Elsevier Ltd. All rights reserved.