Lightweight, Strong, and Resilient 3D Graphene Metamaterial via a Multi-flow Assembly

Materials aim to integrate excellent properties, including high strength, stiffness, significant elastic deformation, specifically at low density. However, synthetic materials usually involve trade-offs among these characteristics, resulting in distinct categories, such as hard and soft carbon materials, despite sharing identical elemental composition. Here, we demonstrate a lightweight graphene metamaterial fabricated via multi-flow assembly that integrates the mechanical robustness of low-density hard carbons with the elastic deformability of soft carbons. The representative graphene metamaterial features a cuttlebone-inspired lamella-wall architecture. This architecture reasonably strengthens and stiffens the graphene metamaterial, akin to the house-of-cards carbon layer arrangement in hard carbons. The intrinsic superelasticity under huge deformation (90%) is also retained in these graphene metamaterials. Our multi-flow assembly method is facile to prepare varied metamaterials by directly manipulating the arranged texture of individual graphene sheets, paving the way for exploring the unique properties of metamaterials in the macroscopic world and their applications.