Construction of PI-MXene-MWCNT nanocomposite film integrating conductive gradient with sandwich structure for high-efficiency electromagnetic interference shielding in extreme environments

Modern electronic equipment puts forward stricter requirements for the performance of electromagnetic interference (EMI) shielding materials to cope with the increasingly complex electromagnetic environment. Here, a high-performance polyimide-MXene-multi-wall carbon nanotubes (PI-MXene-MWCNT) nanocomposite films were prepared by a highly controllable electrospinning-spraying process using the design strategy of integrating conductive gradient with the sandwich structure. The top layer and bottom layer of the composite films are PI electrospun fiber films, and the middle layer is composed by MXene and MWCNT. The design strategy of the conductive gradient structure significantly enhances the EMI shielding performance without increasing the filler content, as evidenced by the nanocomposite film's high EMI shielding effectiveness of 66.8 dB and a satisfactory absolute shielding efficiency of 13153.8 dB cm² g⁻¹. The design strategy of PI sandwich structure endows the nanocomposite film with excellent comprehensive performance. The nanocomposite film not only maintains efficient EMI shielding performance in various extreme conditions, but also has excellent thermal insulation performance (30.5 mW/(m·K)) and flame retardation performance. Meanwhile, the nanocomposite film exhibits good mechanical properties and flexibility, as evidenced by an elongation at break of up to 35.4 %. This work provides inspiration for the preparation of a high-performance EMI shielding material that can be used in extreme environments, which has broad application potential in the field of EMI shielding.