High-performance electromagnetic interference (EMI) shielding materials with ultraflexibility, outstanding mechanical properties, and superior EMI shielding performances are highly desirable for modern integrated electronic and telecommunication systems in areas such as aerospace, military, artificial intelligence, and smart and wearable electronics. Herein, ultraflexible and mechanically strong aramid nanofiber−Ti 3 C 2 T x MXene/silver nanowire (ANF-MXene/AgNW) nanocomposite papers with double-layered structures are fabricated via the facile two-step vacuum-assisted filtration followed by hot-pressing approach. The resultant doublelayered nanocomposite papers with a low MXene/AgNW content of 20 wt % exhibit an excellent electrical conductivity of 922.0 S•cm −1 , outstanding mechanical properties with a tensile strength of 235.9 MPa and fracture strain of 24.8%, superior EMI shielding effectiveness (EMI SE) of 48.1 dB, and high EMI SE/t of 10 688.9 dB•cm −1 , benefiting from the highly efficient double-layered structures, high-performance ANF substrate, and extensive hydrogen-bonding interactions. Particularly, the nanocomposite papers show a maximum electrical conductivity of 3725.6 S•cm −1 and EMI SE of ∼80 dB at a MXene/AgNW content of 80 wt % with an absorption-dominant shielding mechanism owing to the massive ohmic losses in the highly conductive MXene/AgNW layer, multiple internal reflections between Ti 3 C 2 T x MXene nanosheets and polarization relaxation of localized defects, and abundant terminal groups. Compared with the homogeneously blended ones, the double-layered nanocomposite papers possess greater advantages in electrical, mechanical, and EMI shielding performances. Moreover, the multifunctional double-layered nanocomposite papers exhibit excellent thermal management performances such as high Joule heating temperature at low supplied voltages, rapid response time, sufficient heating stability, and reliability. The results indicate that the double-layered nanocomposite papers have excellent potential for high-performance EMI shielding and thermal management applications in aerospace, military, artificial intelligence, and smart and wearable electronics.

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Dielectric materials can be used to control/ store charge and electric energy, which has important potential application value for the dielectric energy storage and intelligent sensing in areas such as aerospace, electronics, and military engineering. [1,2] The dielectric materials with high dielectric permittivity (ε 0 ) and low dielectric loss (tanδ) are of great significance to national security defense and economic development. [3][4][5][6] Ceramic-based dielectric materials are widely used in electronic components in communication, military, and other related fields due to their extremely high dielectric permittivity. [7][8][9] However, the complex preparation process, high processing temperature, brittleness, and low breakdown strength of ceramics greatly limit their application range. [10] Polymers are the industrial choice of dielectric materials for charge storage applications mainly because of their high breakdown strength and excellent processability. Nevertheless, it is a great challenge that the pure polymers always have a very low dielectric permittivity. [11][12][13] Therefore, the high dielectric composite materials obtained by integrating high dielectric particles and polymers in a certain physical/chemical way have great application prospects. One common approach is to add ceramic fillers such as barium titanate (BaTiO 3 ), barium strontium titanate (Ba x Sr 1-x TiO 3 ), and calcium copper titanate (CaCu 3 Ti 4 O 12 ) to the polymers to improve their dielectric properties. [14][15][16][17] However, a higher dielectric permittivity usually requires a higher loading of ceramic filler, which affects the machinability and mechanical strength of the composites. Another approach is to add conductive fillers such as Cu, Ag, graphene, and carbon nanotubes (CNTs) to the polymers, which can obtain very high dielectric permittivity at a low conductive filler loading. [18][19][20][21][22][23] Unfortunately, the conductive fillers are prone to agglomerate, resulting in excessive leakage current, which will cause the sharp increase in dielectric loss of the conductive filler/polymer composites. In recent years, researchers have been keen to combine

Multifunctional wearable electronic devices based on natural materials are highly desirable for versatile applications of energy conversion, electronic skin and artificial intelligence. Herein, multifunctional wearable silver nanowire decorated leather (AgNW/leather) nanocomposites with hierarchical structures for integrated visual Joule heating, electromagnetic interference (EMI) shielding and piezoresistive sensing are fabricated via the facile vacuum‐assisted filtration process. The AgNWs penetrate the micro‐nanoporous structures in the corium side of leather constructing highly‐efficient conductive networks. The resultant flexible and mechanically strong AgNW/leather nanocomposites exhibit extremely low sheet resistance of 0.8 Ω/sq, superior visual Joule heating temperatures up to 108 °C at low supplied voltage of 2.0 V due to efficient energy conversion, excellent EMI shielding effectiveness (EMI SE) of ≈55 dB and outstanding piezoresistive sensing ability in human motion detection. This work demonstrates the fabrication of multifunctional AgNW/leather nanocomposites for next‐generation wearable electronic devices in energy conversion, electronic skin and artificial intelligence, etc.