Hierarchically Structured Composite Decorated with Core‐Sheath CoC@Carbon Fiber Felt: Exceptional Electromagnetic Interference Shielding and Applications in Thermal Management and Electro/Photo‐Thermal Conversion

Abstract In the microelectronics era, electromagnetic radiation and heat accumulation in electronic devices are urgent challenges requiring solutions, particularly through the use of structure‐function integrated and lightweight materials for electromagnetic interference (EMI) shielding and thermal management. Hierarchically structured polyether‐ether‐ketone‐based composites are prepared in this study by in situ deposition and dip coating using a simple and scalable method. Magnetic cobalt nanoparticles derived from magnetic metal–organic frameworks are deposited on carbon fiber felt featuring a macroscopic continuous conductive network. Next, a hybrid slurry is applied to connect the isolated fibers, which bridge the fiber gaps to create new electron and phonon transport channels, increasing the thermal conductivity (23.43 W m −1 K −1 in plane, 4.84 W m −1 K −1 through plane) for efficient heat dissipation. Owing to the stable 3D crosslinked network with high electrical conductivity (13 608 S m −1 ), the composite offers ultra‐high EMI shielding in the X‐band (101.64 dB with stability in extreme environments), excellent Joule heating performance (220 °C at 4 V), and excellent photothermal conversion (94 °C at 500 mW cm −2 ). This multifunctional composite material has great application prospects in precision electronic equipment.