Lightweight and flexible carbon nanotube-nickel nanoparticle/polyimide composite film for EMI shielding

Electromagnetic wave pollution is becoming increasingly serious, which negatively affects both electronic devices and human health. There is an urgent demand to prepare the composites with light weight, high mechanical properties, and excellent electromagnetic interference (EMI) shielding performance. Herein, carbon nanotube-nickel nanoparticle/polyimide (CNT-Ni/PI) composite films were prepared through electrospinning, vacuum filtration, and coating methods. The composite film showed high mechanical performance due to the interface reinforcement effect. When the nickel nanoparticle content reached 2 wt%, the CNT-Ni/PI composite presented a tensile strength of 42.1 MPa and a Young's modulus of 710.5 MPa. Due to high conductivity, the carbon nanotube layer of the composite could efficiently reflect electromagnetic waves. Ni nanoparticles coated the surface of the PI film and generated magnetic loss and interfacial polarization loss at the interface to absorb the electromagnetic wave. Based on the synergistic effect of reflection and absorbing losses, the composite film achieved excellent EMI shielding effectiveness, and its total shielding effectiveness reached 81.45 dB in the X-band. Moreover, the specific shielding effectiveness (SSE) of the CNT-2Ni/PI composite film achieved the maximum value of 9819.28 dB·cm²/g when its thickness and areal density were 0.17 mm and 0.0083 g/cm², respectively. Therefore, the lightweight and flexible CNT–Ni/PI composite film is highly promising for application as an EMI shielding layer in wearable electronics and radar.