Flexible sandwich-structured silver nanowire/exfoliated graphite platelet/aramid nanofiber composite films with excellent EMI shielding, thermal conduction and Joule heating performances

Multifunctional flexible sandwich-structured EMI shielding silver nanowire/exfoliated graphite platelet/aramid nanofiber (AgNW/EGP/ANF) composite films with excellent thermal conduction and Joule heating abilities were successfully prepared by a layer-by-layer vacuum filtration technique. The construction of EGP/ANF layer on the two sides is crucial in achieving outstanding thermal conductivity (TC) and contributes partial EMI shielding effectiveness (SE) for the composite films. The introduction of an ultrathin, dense, and sintered AgNW/ANF layer endows the composite films with significant enhancements in electrical conductivity and EMI SE. As a result, the optimal 30 μm-thick composite films with an AgNW loading of 35 wt% exhibit excellent EMI SE values of 69.0 dB in the X-band and 78.4 dB in the Ka-band and a superior in-plane TC of 48.7 W m⁻¹ K⁻¹. Besides, the prepared composite films present an outstanding Joule heating performance. Briefly, the sandwich-structured composite films show huge potential in advanced portable and wearable electronic applications.