Flexible Aramid Nanofiber/Bacterial Cellulose/Graphene Papers with Nickel Nanoparticles for Enhanced Electromagnetic Interference Shielding and Joule Heating Performance

High-mechanical strength and flexible multifunctional composite films with superior electromagnetic interface (EMI) shielding and rapid-response Joule heating are of urgent demand for the development of wearable devices. Herein, we fabricated the aramid nanofibers (ANFs)/bacterial cellulose (BC)/graphene nanosheets (GNs)/nickel nanoparticles (Ni NPs) composite films via vacuum-assisted filtration followed by the electron beam evaporation method. Mechanical properties of ANF/BC composite papers could be tuned by changing the weight ratio of ANFs and BC. Benefiting from the outstanding electrical conductivity of the magnetic Ni NPs, the ANF/BC-3/GNs/Ni-300 composite film (ANF/BC-3 represents that the weight ratio of ANFs to BC is 7:3, and Ni-300 represents that the thickness of Ni is 300 nm) exhibited superior electrical conductivity up to 328 S/cm and displayed superb EMI shielding effectiveness exceeding 50 dB in the whole X band (8-12.4 GHz). Meanwhile, the EMI shielding effectiveness of the film could still be maintained above 40 dB after bending 1000 times by 150 degrees due to the excellent tensile properties of ANF/BC-3 films. Furthermore, the ANF/BC-3/GNs/Ni-300 composite film also showed great Joule heating performance (135 degrees C at 5 V) with rapid response (<7 s), durability and repeatability (50 cycles), and long-term stability (1800 s) without obvious temperature fluctuation. These results showed that the ANF/BC-3/GNs/Ni-300 composite film could be used in intelligent wearable devices and maintain excellent electromagnetic shielding performances.