Cellulose nanofiber/silver nanowire-based composites for X-band electromagnetic interference shielding: Structure-performance relationships and multifunctional applications - A review.

The rapid development of flexible electronics has increased the demand for lightweight, flexible, low-reflection, and multifunctional electromagnetic interference (EMI) shielding materials. Cellulose nanofiber/silver nanowire (CNF/AgNW) composites offer a promising combination of a bio-based scaffold and conductive networks, but their structure-performance relationships have not yet been synthesized in a focused manner. This review analyzes 47 articles identified through a Scopus search conducted on 27 April 2026, focusing on CNF/AgNW composites reporting EMI shielding performance in the X-band (8.2-12.4 GHz). The evaluation covers SET, SER, SEA, R, A, SE/t, SSE, SSE/t, mechanical properties, additional functionalities, composition, and architecture. Single-layer composites exhibit SET values of 4.6-106.3 dB, whereas multilayer composites reach 20.0-110.3 dB. The median SET increases from 49.9 to 71.9 dB for multilayer structures, but the median SSE/t values are nearly comparable, at 10,240 and 11,017 dB cm2 g-1, respectively, indicating that higher absolute attenuation is not necessarily accompanied by improved mass-thickness efficiency. Electrical conductivity, AgNW loading, and architectural class do not show monotonic relationships with SET. Reflection-absorption analysis shows that similar SET values can arise from different energy distributions, while the incident side can alter reflection in asymmetric structures. Shielding performance also does not increase consistently with tensile strength, stiffness, elongation, or toughness. Thermal management, Joule heating, photothermal conversion, sensing, energy harvesting/storage, and antibacterial performance impose material requirements that are partly compatible and partly competitive with shielding. Controlled conductive-network continuity, interfacial stabilization, filler hybridization, and spatial organization emerge as key design variables. Compared with PVA, PU, and PI-based AgNW matrices, CNF offers aqueous processability, renewable matrix origin, fibrous load-bearing support, and stabilization of the AgNW network, but remains limited by moisture sensitivity, tensile extensibility, AgNW requirements, and durability. CNF/AgNW performance is governed by the coordination of conductive networks, interfaces, architecture, material efficiency, and mechanical and functional requirements. These findings direct the development of CNF/AgNW composites away from maximizing SET or conductivity alone toward multi-objective optimization that maintains high attenuation while reducing reflection and material use without compromising mechanical reliability or secondary functionalities, thereby supporting lightweight, low-reflection, and multifunctional shielding for flexible electronics.