Novel Cellulosic Fiber Composites with Integrated Multi-Band Electromagnetic Interference Shielding and Energy Storage Functionalities

Abstract In an era where technological advancement and sustainability converge, developing renewable materials with multifunctional integration is increasingly in demand. This study filled a crucial gap by integrating energy storage, multi-band electromagnetic interference (EMI) shielding, and structural design into bio-based materials. Specifically, conductive polymer layers were formed within the 2,2,6,6-tetramethylpiperidine-1-oxide (TEMPO)-oxidized cellulose fiber skeleton, where a mild TEMPO-mediated oxidation system was applied to endow it with abundant macropores that could be utilized as active sites (specific surface area of 105.6 m 2 g −1 ). Benefiting from the special hierarchical porous structure of the material, the constructed cellulose fiber-derived composites can realize high areal-specific capacitance of 12.44 F cm −2 at 5 mA cm −2 and areal energy density of 3.99 mWh cm −2 (2005 mW cm −2 ) with an excellent stability of maintaining 90.23% after 10,000 cycles at 50 mA cm −2 . Meanwhile, the composites showed a high electrical conductivity of 877.19 S m −1 and excellent EMI efficiency (> 99.99%) in multiple wavelength bands. The composite material’s EMI values exceed 100 dB across the L, S, C, and X bands, effectively shielding electromagnetic waves in daily life. The proposed strategy paves the way for utilizing bio-based materials in applications like energy storage and EMI shielding, contributing to a more sustainable future.