Ultralight\nand Highly Elastic Graphene/Lignin-Derived Carbon Nanocomposite Aerogels\nwith Ultrahigh Electromagnetic Interference Shielding Performance

Abstract

Ultralight\nand highly elastic reduced graphene oxide (RGO)/lignin-derived carbon\n(LDC) composite aerogels with aligned micron-sized pores and cell\nwalls are prepared using a facile freeze-drying method. The presence\nof a small fraction of LDC in the cell walls enhances the interfacial\npolarization effect while almost maintaining the amount of charge\ncarriers and conductivity of the cell walls, greatly boosting the\nwave absorption capability of the cell walls. RGO/LDC aerogels also\nshow a greater number of large cell walls with better integrity than\nRGO aerogels, further improving the multiple reflection ability of\nthe aligned cell walls. Synergistic effects of the multiphase cell\nwalls and the preferred microstructures of the RGO/LDC aerogels lead\nto their high electromagnetic interference (EMI) shielding effectiveness\nof 21.3–49.2 dB at an ultralow density of 2.0–8.0 mg/cm³. This corresponds to the surface-specific SE (SE divided\nby density and thickness) up to 53 250 dB·cm²/g, which is higher than the values reported for other carbon- and\nmetal-based shields. Furthermore, the critical roles that microstructures\nplay in determining the EMI shielding performance are directly revealed\nby comparing the shielding performance in directions parallel and\nnormal to cell walls, as well as in an in situ compression process.