Ferrite-Decorated Ultrathin and Lightweight Carbon Nanotube Film for Electromagnetic Interference Shielding

High-performance electromagnetic interference (EMI) shielding is urgently needed for next-generation electronic devices that are becoming more sensitive and minimized. The current EMI-shielding materials and metals have adaptation issues because of their high density and corrosion. Therefore, several alternatives have been investigated to overcome these obstacles. Although some of these materials satisfy commercial shielding efficiency (SE) requirements, their capability for commercial mass production is doubtful. In this work, a freestanding carbon nanotube (CNT) film is synthesized via direct spinning and decorated with ferrite nanoparticles (FCNTs) to achieve good magnetic permeability without using any binder. According to the overall research, the size of ferrite nanoparticles greatly impacts magnetic properties, and the FCNT composite exhibits a superparamagnetic property due to the nanosized ferrite particles. Therefore, FCNT shows good magnetic permeability and high electrical conductivity, two main factors affecting SE improvement. As a result, FCNT exhibits 10 times higher specific SE than a copper foil, even though it is nearly 2 times thinner. Also, the FCNT composite film with 25 μm thickness exhibits an SE of 91.4 dB, which exceeds the commercial SE threshold and the SE of copper foil of the same thickness. The results show that the FCNT composite film has great potential for utilization as an ultrathin freestanding EMI-shielding material.