Flexible and Superhigh Electromagnetic Interference Shielding Film with Porous Alternating Pva-Derived Carbon and Graphene Layers

Recently, the design of graphene-based films with elaborately controlled microstructures and optimized electromagnetic interference shielding (EMI) properties can effectively improve EM energy attenuation and conversion. Herein, inspired by the structure of multi-layer steamed bread, an alternating multilayered structure with polyvinyl alcohol (PVA)-derived carbon layers and graphene/electrospun carbon nanofibers layers was designed through a feasible alternating vacuum-assisted filtration method. Benefiting from the synergy of the multi-interfaces and multiple reflection with porous alternating structure, the composite film exhibited favorable impedance matching, abundant loss mechanism, and superhigh EMI shielding ability, resulting in absorption dominated shielding characteristic. Thus, the resultant 7-layer alternating composite films with a thickness of 160 μm achieved an EMI shielding effectiveness (EMI SE) of up to 80 dB in the X-band, and the average electromagnetic reflection was as low as 16 dB. Furthermore, the excellent mechanical flexibility ensured the stable EMI shielding and electrical properties, which can withstand the folding test more than 250 times without obvious reduction. Taken together, this effort opens a creative avenue for designing and constructing flexible composite films with superhigh EMI shielding performance.