Multifunctional carbon fiber@NiCo/polyimide films with outstanding electromagnetic interference shielding performance

The electromagnetic interference (EMI) shielding materials with low reflection characteristics are highly desirable for integrated communication and microelectronics systems to shield EM waves and their secondary pollution. In this study, the EMI shielding materials with outstanding absorption performance were fabricated via the two-step pyrolysis and followed by vacuum assisted filtration approach. The chopped carbon fibers (CFs) wrapped with NiCo₂O₄ nanowire arrays (CF@NiCo₂O₄) were prepared by the hydrothermal reaction initially. After annealing, the NiCo₂O₄ nanowires transformed into NiCo alloy nanoparticles and evenly embedded in the CFs, endowing the CF@NiCo composites with efficient magnetic loss and dielectric loss capacity. After vacuum filtration and encapsulation with polyimide, the obtained flexible CF@NiCo/polyimide composite film displays superior EMI shielding effectiveness of 87 dB with a thickness of only 1.08 mm. Particularly, the composite film exhibits extremely low SE_R characteristics of ~6 dB, which surpasses those of most previously reported composites materials with similar thickness. In addition, the composite films present outstanding flexibility, mechanical properties and Joule heating performances. Therefore, the prepared flexible composite films have broad prospect for EMI shielding and thermal management applications in advanced microelectronic systems.