Multifunctional\nFlexible Electromagnetic Interference Shielding Silver Nanowires/Cellulose\nFilms with Excellent Thermal Management and Joule Heating Performances

Abstract

Flexible electromagnetic\ninterference (EMI) shielding materials with excellent thermal conductivities\nand Joule heating performances are of urgent demand in the communication\nindustry, artificial intelligence, and wearable electronics. In this\nwork, highly conductive silver nanowires (AgNWs) were prepared using\nthe polyol method. Cellulose sheets were then prepared by dissolving\nnatural cotton in a green and efficient NaOH/urea aqueous solution.\nFinally, multifunctional flexible EMI shielding AgNWs/cellulose films\nwere fabricated based on vacuum-assisted filtration and hot-pressing.\nAgNWs are evenly embedded in the inner cellulose matrix and overlap\nwith each other to form a 3D network. AgNWs/cellulose films, with\na thickness of 44.5 μm, obtain the superior EMI shielding effectiveness\nof 101 dB, which is the highest value ever reported for shielding\nmaterials with the same thickness. In addition, AgNWs/cellulose films\npresent excellent tensile strength (60.7 MPa) and tensile modulus\n(3.35 GPa), ultrahigh electrical conductivity (σ, 5571 S/cm),\nand excellent in-plane thermal conductivity coefficient (λ_∥, 10.55 W/mK), which can effectively dissipate the\nheat accumulation. Interestingly, AgNWs/cellulose films also show\noutstanding Joule heating performances, good stability, and sensitive\ntemperature response at driving voltages, absolutely safe for the\nhuman body. Therefore, our fabricated multifunctional flexible AgNWs/cellulose\nfilms have broad prospects in the fields of EMI shielding and protection\nof outdoor large-scale power transformers and wearable electronics.