A <scp>PEEK</scp> Composite Paper Maintaining High Electromagnetic Shielding Properties Under a Wide Temperature Region and Cyclic Near Infrared High Power Laser Irradiation

ABSTRACT Lightweight, environmentally resistant electromagnetic shielding materials are critical for aerospace and military applications. Constructing multi‐layer conductive network structure offers an effective pathway to achieve high‐performance electromagnetic interference (EMI) shielding. In this work, we developed a lightweight fiber‐reinforced composite paper that delivered ultra‐high EMI shielding performance (SE) even under harsh conditions. A three‐dimensional conductive network was formed by the controlled incorporation of Cu@PEEK fibers and carbon fibers (CFs) into a carbon nanotubes (CNTs)/PEEK fiber matrix. Experimental results revealed remarkable synergistic effects among the multi‐scale fibers, endowing the composite paper with an exceptional EMI shielding effectiveness of 54.4 dB at an ultra‐thin thickness of 0.3 mm (12 GHz). Furthermore, the stability of the EMI shielding performance was evaluated under extreme temperatures and near‐infrared high‐power laser irradiation. The composite paper retains over 80% of its shielding effectiveness, demonstrating the potential for application in complex environments. This work provides valuable insights for designing high‐stability EMI shielding materials suited for extreme operational environments.