Ultralight\nand Highly\nConductive Silver Nanowire Aerogels\nfor High-Performance Electromagnetic Interference Shielding

Abstract

Metal-based materials possess superior\nelectromagnetic\ninterference\n(EMI) shielding performance because of their extraordinary electrical\nconductivity. Nevertheless, the high density and structural rigidity\nof metals seriously limit their applicability in portable and wearable\nelectronic equipment. A common method for reducing the density of\nmetal-based materials is to prepare metal nanowire aerogels by freeze-drying,\nbut the weak connection among the nanowires results in poor mechanical\nand electrical properties. Herein, a facile approach is developed\nfor the one-step synthesis of silver nanowire (AgNW) aerogels with\nultralow density, good flexibility, high electrical conductivity,\nand a robust structure. The gel is directly formed by in situ assembly\nof AgNWs. The end-to-end nanojoining of AgNWs contributes to constructing\nan interconnected three-dimensional (3D) network, resulting in improved\nmechanical and electrical properties. The AgNW aerogel with an ultralow\ndensity of 4.87 mg cm^–3 demonstrates a high electrical\nconductivity of 4584 S m^–1. Moreover, the porous\nstructure of the AgNW aerogel provides numerous interfaces for multiple\nreflections and scattering of EM waves, allowing them to be continuously\nabsorbed and dissipated within the aerogel. Thus, the AgNW aerogel\nexhibits a superb EMI shielding effectiveness (SE) of 109.3 dB and\na normalized surface specific SE (SSE/<i>t</i>, calculated\nas the SE divided by the density and thickness) of 353 183\ndB cm² g^–1, significantly above that\nof previously known shielding materials. This work provides a new\nroute for preparing high-performance metal nanowire aerogels and their\ngreat potential in EMI shielding.