Lightweight Polyimide Nanocomposites with 3D Cocarbonized MXene/Carbon Fiber Networks for Electromagnetic Interference Shielding and High-Temperature Stability

The growing deployment of 5G communication systems has sharply escalated the demand for high-performance electromagnetic interference (EMI) shielding materials with outstanding thermal stability and efficiency. Carbon fiber (CF), recognized for its cost-effectiveness and environmental sustainability, has shown significant promise in the development of EMI shielding composites. Nevertheless, achieving a balance of lightweight structure, superior shielding efficiency, and thermal endurance remains a formidable challenge. In this study, a streamlined fabrication process was utilized to develop a multifunctional, lightweight nanocomposite. MXene was synthesized via in situ etching of the MAX phase with hydrofluoric (HF) acid, followed by the construction of a three-dimensional (3D) cocarbonized network comprising interconnected CF, MXene, and MXene-derived phases (CMXene) via a straightforward cocarbonization process. The polyimide (PI) matrix was uniformly infused into the porous framework using a precisely controlled impregnation technique, resulting in a PI-based nanocomposite with exceptional EMI shielding performance. At a filler content of 14.3 wt % and a thickness of 1.7 mm, the nanocomposite demonstrated an EMI shielding effectiveness (EMI SE) of 73.8 dB in the X-band ranging from 8.2 to 12.4 GHz, maintaining 63.3 dB even at high temperatures of 400 °C, reflecting an 85.8% retention rate. This ultralight nanocomposite, characterized by excellent EMI shielding efficiency and robust thermal stability, offers significant potential for advanced applications in electronic devices, such as battery management systems in energy vehicles and in-vehicle communication modules, to ensure system stability and prevent EMI-induced signal disruption.